Ocfs2 devel - Oct 2018 - [PATCH 04/26] vfs: exit early from zero length remap operations

Hi all,

Dave, Eric, and I have been chasing a stale data exposure bug in the XFS
reflink implementation, and tracked it down to reflink forgetting to do
some of the file-extending activities that must happen for regular
writes.

We then started auditing the clone, dedupe, and copyfile code and
realized that from a file contents perspective, clonerange isn't any
different from a regular file write.  Unfortunately, we also noticed
that *unlike* a regular write, clonerange skips a ton of overflow
checks, such as validating the ranges against s_maxbytes, MAX_NON_LFS,
and RLIMIT_FSIZE.  We also observed that cloning into a file did not
strip security privileges (suid, capabilities) like a regular write
would.  I also noticed that xfs and ocfs2 need to dump the page cache
before remapping blocks, not after.

In fixing the range checking problems I also realized that both dedupe
and copyfile tell userspace how much of the requested operation was
acted upon.  Since the range validation can shorten a clone request (or
we can ENOSPC midway through), we might as well plumb the short
operation reporting back through the VFS indirection code to userspace.

So, here's the whole giant pile of patches[1] that fix all the problems.
This branch is against current upstream (4.19-rc8).  The patch
"generic: test reflink side effects" recently sent to fstests
exercises
the fixes in this series.  Tests are in [2].

--D

[1]
https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfs-linux.git/log/?h=djwong-devel
[2]
https://git.kernel.org/pub/scm/linux/kernel/git/djwong/xfstests-dev.git/log/?h=djwong-devel

From: Darrick J. Wong <darrick.wong at oracle.com>

Add a "xfs_tprintk" macro so that developers can use trace_printk to
print out arbitrary debugging information with the XFS device name
attached to the trace output.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
---
 fs/xfs/xfs_error.h |    6 ++++++
 1 file changed, 6 insertions(+)


diff --git a/fs/xfs/xfs_error.h b/fs/xfs/xfs_error.h
index 246d3e989c6c..5caa8bdf6c38 100644
--- a/fs/xfs/xfs_error.h
+++ b/fs/xfs/xfs_error.h
@@ -76,6 +76,11 @@ extern int xfs_errortag_set(struct xfs_mount *mp, unsigned
int error_tag,
 		unsigned int tag_value);
 extern int xfs_errortag_add(struct xfs_mount *mp, unsigned int error_tag);
 extern int xfs_errortag_clearall(struct xfs_mount *mp);
+
+/* trace printk version of xfs_err and friends */
+#define xfs_tprintk(mp, fmt, args...) \
+	trace_printk("dev %d:%d " fmt, MAJOR((mp)->m_super->s_dev), \
+			MINOR((mp)->m_super->s_dev), ##args)
 #else
 #define xfs_errortag_init(mp)			(0)
 #define xfs_errortag_del(mp)
@@ -83,6 +88,7 @@ extern int xfs_errortag_clearall(struct xfs_mount *mp);
 #define xfs_errortag_set(mp, tag, val)		(ENOSYS)
 #define xfs_errortag_add(mp, tag)		(ENOSYS)
 #define xfs_errortag_clearall(mp)		(ENOSYS)
+#define xfs_tprintk(mp, fmt, args...)		do { } while (0)
 #endif /* DEBUG */
 
 /*

From: Darrick J. Wong <darrick.wong at oracle.com>

vfs_clone_file_prep_inodes cannot return 0 if it is asked to remap from
a zero byte file because that's what btrfs does.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
Reviewed-by: Christoph Hellwig <hch at lst.de>
---
 fs/read_write.c |    3 ---
 1 file changed, 3 deletions(-)


diff --git a/fs/read_write.c b/fs/read_write.c
index 8a2737f0d61d..260797b01851 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1740,10 +1740,7 @@ int vfs_clone_file_prep_inodes(struct inode *inode_in,
loff_t pos_in,
 	if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
 		return -EINVAL;
 
-	/* Are we going all the way to the end? */
 	isize = i_size_read(inode_in);
-	if (isize == 0)
-		return 0;
 
 	/* Zero length dedupe exits immediately; reflink goes to EOF. */
 	if (*len == 0) {

From: Darrick J. Wong <darrick.wong at oracle.com>

Move the file range checks from vfs_clone_file_prep into a separate
generic_remap_checks function so that all the checks are collected in a
central location.  This forms the basis for adding more checks from
generic_write_checks that will make cloning's input checking more
consistent with write input checking.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
Reviewed-by: Christoph Hellwig <hch at lst.de>
Reviewed-by: Amir Goldstein <amir73il at gmail.com>
---
 fs/ocfs2/refcounttree.c |    2 +
 fs/read_write.c         |   55 +++++++++----------------------------
 fs/xfs/xfs_reflink.c    |    2 +
 include/linux/fs.h      |    9 ++++--
 mm/filemap.c            |   69 +++++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 90 insertions(+), 47 deletions(-)


diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index 7a5ee145c733..19e03936c5e1 100644
--- a/fs/ocfs2/refcounttree.c
+++ b/fs/ocfs2/refcounttree.c
@@ -4850,7 +4850,7 @@ int ocfs2_reflink_remap_range(struct file *file_in,
 	    (OCFS2_I(inode_out)->ip_flags & OCFS2_INODE_SYSTEM_FILE))
 		goto out_unlock;
 
-	ret = vfs_clone_file_prep_inodes(inode_in, pos_in, inode_out, pos_out,
+	ret = vfs_clone_file_prep(file_in, pos_in, file_out, pos_out,
 			&len, is_dedupe);
 	if (ret <= 0)
 		goto out_unlock;
diff --git a/fs/read_write.c b/fs/read_write.c
index 260797b01851..d6e8e242a15f 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1717,13 +1717,12 @@ static int clone_verify_area(struct file *file, loff_t
pos, u64 len, bool write)
  * Returns: 0 for "nothing to clone", 1 for "something to
clone", or
  * the usual negative error code.
  */
-int vfs_clone_file_prep_inodes(struct inode *inode_in, loff_t pos_in,
-			       struct inode *inode_out, loff_t pos_out,
-			       u64 *len, bool is_dedupe)
+int vfs_clone_file_prep(struct file *file_in, loff_t pos_in,
+			struct file *file_out, loff_t pos_out,
+			u64 *len, bool is_dedupe)
 {
-	loff_t bs = inode_out->i_sb->s_blocksize;
-	loff_t blen;
-	loff_t isize;
+	struct inode *inode_in = file_inode(file_in);
+	struct inode *inode_out = file_inode(file_out);
 	bool same_inode = (inode_in == inode_out);
 	int ret;
 
@@ -1740,10 +1739,10 @@ int vfs_clone_file_prep_inodes(struct inode *inode_in,
loff_t pos_in,
 	if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
 		return -EINVAL;
 
-	isize = i_size_read(inode_in);
-
 	/* Zero length dedupe exits immediately; reflink goes to EOF. */
 	if (*len == 0) {
+		loff_t isize = i_size_read(inode_in);
+
 		if (is_dedupe || pos_in == isize)
 			return 0;
 		if (pos_in > isize)
@@ -1751,36 +1750,11 @@ int vfs_clone_file_prep_inodes(struct inode *inode_in,
loff_t pos_in,
 		*len = isize - pos_in;
 	}
 
-	/* Ensure offsets don't wrap and the input is inside i_size */
-	if (pos_in + *len < pos_in || pos_out + *len < pos_out ||
-	    pos_in + *len > isize)
-		return -EINVAL;
-
-	/* Don't allow dedupe past EOF in the dest file */
-	if (is_dedupe) {
-		loff_t	disize;
-
-		disize = i_size_read(inode_out);
-		if (pos_out >= disize || pos_out + *len > disize)
-			return -EINVAL;
-	}
-
-	/* If we're linking to EOF, continue to the block boundary. */
-	if (pos_in + *len == isize)
-		blen = ALIGN(isize, bs) - pos_in;
-	else
-		blen = *len;
-
-	/* Only reflink if we're aligned to block boundaries */
-	if (!IS_ALIGNED(pos_in, bs) || !IS_ALIGNED(pos_in + blen, bs) ||
-	    !IS_ALIGNED(pos_out, bs) || !IS_ALIGNED(pos_out + blen, bs))
-		return -EINVAL;
-
-	/* Don't allow overlapped reflink within the same file */
-	if (same_inode) {
-		if (pos_out + blen > pos_in && pos_out < pos_in + blen)
-			return -EINVAL;
-	}
+	/* Check that we don't violate system file offset limits. */
+	ret = generic_remap_checks(file_in, pos_in, file_out, pos_out, len,
+			is_dedupe);
+	if (ret)
+		return ret;
 
 	/* Wait for the completion of any pending IOs on both files */
 	inode_dio_wait(inode_in);
@@ -1813,7 +1787,7 @@ int vfs_clone_file_prep_inodes(struct inode *inode_in,
loff_t pos_in,
 
 	return 1;
 }
-EXPORT_SYMBOL(vfs_clone_file_prep_inodes);
+EXPORT_SYMBOL(vfs_clone_file_prep);
 
 int do_clone_file_range(struct file *file_in, loff_t pos_in,
 			struct file *file_out, loff_t pos_out, u64 len)
@@ -1851,9 +1825,6 @@ int do_clone_file_range(struct file *file_in, loff_t
pos_in,
 	if (ret)
 		return ret;
 
-	if (pos_in + len > i_size_read(inode_in))
-		return -EINVAL;
-
 	ret = file_in->f_op->clone_file_range(file_in, pos_in,
 			file_out, pos_out, len);
 	if (!ret) {
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 42ea7bab9144..281d5f53f2ec 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -1326,7 +1326,7 @@ xfs_reflink_remap_prep(
 	if (IS_DAX(inode_in) || IS_DAX(inode_out))
 		goto out_unlock;
 
-	ret = vfs_clone_file_prep_inodes(inode_in, pos_in, inode_out, pos_out,
+	ret = vfs_clone_file_prep(file_in, pos_in, file_out, pos_out,
 			len, is_dedupe);
 	if (ret <= 0)
 		goto out_unlock;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 897eae8faee1..ba93a6e7dac4 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1825,9 +1825,9 @@ extern ssize_t vfs_readv(struct file *, const struct iovec
__user *,
 		unsigned long, loff_t *, rwf_t);
 extern ssize_t vfs_copy_file_range(struct file *, loff_t , struct file *,
 				   loff_t, size_t, unsigned int);
-extern int vfs_clone_file_prep_inodes(struct inode *inode_in, loff_t pos_in,
-				      struct inode *inode_out, loff_t pos_out,
-				      u64 *len, bool is_dedupe);
+extern int vfs_clone_file_prep(struct file *file_in, loff_t pos_in,
+			       struct file *file_out, loff_t pos_out,
+			       u64 *count, bool is_dedupe);
 extern int do_clone_file_range(struct file *file_in, loff_t pos_in,
 			       struct file *file_out, loff_t pos_out, u64 len);
 extern int vfs_clone_file_range(struct file *file_in, loff_t pos_in,
@@ -2967,6 +2967,9 @@ extern int sb_min_blocksize(struct super_block *, int);
 extern int generic_file_mmap(struct file *, struct vm_area_struct *);
 extern int generic_file_readonly_mmap(struct file *, struct vm_area_struct *);
 extern ssize_t generic_write_checks(struct kiocb *, struct iov_iter *);
+extern int generic_remap_checks(struct file *file_in, loff_t pos_in,
+				struct file *file_out, loff_t pos_out,
+				uint64_t *count, bool is_dedupe);
 extern ssize_t generic_file_read_iter(struct kiocb *, struct iov_iter *);
 extern ssize_t __generic_file_write_iter(struct kiocb *, struct iov_iter *);
 extern ssize_t generic_file_write_iter(struct kiocb *, struct iov_iter *);
diff --git a/mm/filemap.c b/mm/filemap.c
index 52517f28e6f4..47e6bfd45a91 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2974,6 +2974,75 @@ inline ssize_t generic_write_checks(struct kiocb *iocb,
struct iov_iter *from)
 }
 EXPORT_SYMBOL(generic_write_checks);
 
+/*
+ * Performs necessary checks before doing a clone.
+ *
+ * Can adjust amount of bytes to clone.
+ * Returns appropriate error code that caller should return or
+ * zero in case the clone should be allowed.
+ */
+int generic_remap_checks(struct file *file_in, loff_t pos_in,
+			 struct file *file_out, loff_t pos_out,
+			 uint64_t *req_count, bool is_dedupe)
+{
+	struct inode *inode_in = file_in->f_mapping->host;
+	struct inode *inode_out = file_out->f_mapping->host;
+	uint64_t count = *req_count;
+	uint64_t bcount;
+	loff_t size_in, size_out;
+	loff_t bs = inode_out->i_sb->s_blocksize;
+
+	/* The start of both ranges must be aligned to an fs block. */
+	if (!IS_ALIGNED(pos_in, bs) || !IS_ALIGNED(pos_out, bs))
+		return -EINVAL;
+
+	/* Ensure offsets don't wrap. */
+	if (pos_in + count < pos_in || pos_out + count < pos_out)
+		return -EINVAL;
+
+	size_in = i_size_read(inode_in);
+	size_out = i_size_read(inode_out);
+
+	/* Dedupe requires both ranges to be within EOF. */
+	if (is_dedupe &&
+	    (pos_in >= size_in || pos_in + count > size_in ||
+	     pos_out >= size_out || pos_out + count > size_out))
+		return -EINVAL;
+
+	/* Ensure the infile range is within the infile. */
+	if (pos_in >= size_in)
+		return -EINVAL;
+	count = min(count, size_in - (uint64_t)pos_in);
+
+	/*
+	 * If the user wanted us to link to the infile's EOF, round up to the
+	 * next block boundary for this check.
+	 *
+	 * Otherwise, make sure the count is also block-aligned, having
+	 * already confirmed the starting offsets' block alignment.
+	 */
+	if (pos_in + count == size_in) {
+		bcount = ALIGN(size_in, bs) - pos_in;
+	} else {
+		if (!IS_ALIGNED(count, bs))
+			return -EINVAL;
+
+		bcount = count;
+	}
+
+	/* Don't allow overlapped cloning within the same file. */
+	if (inode_in == inode_out &&
+	    pos_out + bcount > pos_in &&
+	    pos_out < pos_in + bcount)
+		return -EINVAL;
+
+	/* For now we don't support changing the length. */
+	if (*req_count != count)
+		return -EINVAL;
+
+	return 0;
+}
+
 int pagecache_write_begin(struct file *file, struct address_space *mapping,
 				loff_t pos, unsigned len, unsigned flags,
 				struct page **pagep, void **fsdata)

From: Darrick J. Wong <darrick.wong at oracle.com>

If a remap caller asks us to remap to the source file's EOF and the
source file has zero bytes, exit early.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
---
 fs/read_write.c |    2 ++
 1 file changed, 2 insertions(+)


diff --git a/fs/read_write.c b/fs/read_write.c
index d6e8e242a15f..2456da3f8a41 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1748,6 +1748,8 @@ int vfs_clone_file_prep(struct file *file_in, loff_t
pos_in,
 		if (pos_in > isize)
 			return -EINVAL;
 		*len = isize - pos_in;
+		if (*len == 0)
+			return 0;
 	}
 
 	/* Check that we don't violate system file offset limits. */

From: Darrick J. Wong <darrick.wong at oracle.com>

File range remapping, if allowed to run past the destination file's EOF,
is an optimization on a regular file write.  Regular file writes that
extend the file length are subject to various constraints which are not
checked by range cloning.

This is a correctness problem because we're never allowed to touch
ranges that the page cache can't support (s_maxbytes); we're not
supposed to deal with large offsets (MAX_NON_LFS) if O_LARGEFILE isn't
set; and we must obey resource limits (RLIMIT_FSIZE).

Therefore, add these checks to the new generic_remap_checks function so
that we curtail unexpected behavior.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
Reviewed-by: Amir Goldstein <amir73il at gmail.com>
Reviewed-by: Christoph Hellwig <hch at lst.de>
---
 mm/filemap.c |   91 ++++++++++++++++++++++++++++++++++++++--------------------
 1 file changed, 59 insertions(+), 32 deletions(-)


diff --git a/mm/filemap.c b/mm/filemap.c
index 47e6bfd45a91..08ad210fee49 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2915,6 +2915,49 @@ struct page *read_cache_page_gfp(struct address_space
*mapping,
 }
 EXPORT_SYMBOL(read_cache_page_gfp);
 
+static int generic_access_check_limits(struct file *file, loff_t pos,
+				       loff_t *count)
+{
+	struct inode *inode = file->f_mapping->host;
+
+	/* Don't exceed the LFS limits. */
+	if (unlikely(pos + *count > MAX_NON_LFS &&
+				!(file->f_flags & O_LARGEFILE))) {
+		if (pos >= MAX_NON_LFS)
+			return -EFBIG;
+		*count = min(*count, (loff_t)MAX_NON_LFS - pos);
+	}
+
+	/*
+	 * Don't operate on ranges the page cache doesn't support.
+	 *
+	 * If we have written data it becomes a short write.  If we have
+	 * exceeded without writing data we send a signal and return EFBIG.
+	 * Linus frestrict idea will clean these up nicely..
+	 */
+	if (unlikely(pos >= inode->i_sb->s_maxbytes))
+		return -EFBIG;
+
+	*count = min(*count, inode->i_sb->s_maxbytes - pos);
+	return 0;
+}
+
+static int generic_write_check_limits(struct file *file, loff_t pos,
+				      loff_t *count)
+{
+	unsigned long limit = rlimit(RLIMIT_FSIZE);
+
+	if (limit != RLIM_INFINITY) {
+		if (pos >= limit) {
+			send_sig(SIGXFSZ, current, 0);
+			return -EFBIG;
+		}
+		*count = min(*count, (loff_t)limit - pos);
+	}
+
+	return generic_access_check_limits(file, pos, count);
+}
+
 /*
  * Performs necessary checks before doing a write
  *
@@ -2926,8 +2969,8 @@ inline ssize_t generic_write_checks(struct kiocb *iocb,
struct iov_iter *from)
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file->f_mapping->host;
-	unsigned long limit = rlimit(RLIMIT_FSIZE);
-	loff_t pos;
+	loff_t count;
+	int ret;
 
 	if (!iov_iter_count(from))
 		return 0;
@@ -2936,40 +2979,15 @@ inline ssize_t generic_write_checks(struct kiocb *iocb,
struct iov_iter *from)
 	if (iocb->ki_flags & IOCB_APPEND)
 		iocb->ki_pos = i_size_read(inode);
 
-	pos = iocb->ki_pos;
-
 	if ((iocb->ki_flags & IOCB_NOWAIT) && !(iocb->ki_flags &
IOCB_DIRECT))
 		return -EINVAL;
 
-	if (limit != RLIM_INFINITY) {
-		if (iocb->ki_pos >= limit) {
-			send_sig(SIGXFSZ, current, 0);
-			return -EFBIG;
-		}
-		iov_iter_truncate(from, limit - (unsigned long)pos);
-	}
+	count = iov_iter_count(from);
+	ret = generic_write_check_limits(file, iocb->ki_pos, &count);
+	if (ret)
+		return ret;
 
-	/*
-	 * LFS rule
-	 */
-	if (unlikely(pos + iov_iter_count(from) > MAX_NON_LFS &&
-				!(file->f_flags & O_LARGEFILE))) {
-		if (pos >= MAX_NON_LFS)
-			return -EFBIG;
-		iov_iter_truncate(from, MAX_NON_LFS - (unsigned long)pos);
-	}
-
-	/*
-	 * Are we about to exceed the fs block limit ?
-	 *
-	 * If we have written data it becomes a short write.  If we have
-	 * exceeded without writing data we send a signal and return EFBIG.
-	 * Linus frestrict idea will clean these up nicely..
-	 */
-	if (unlikely(pos >= inode->i_sb->s_maxbytes))
-		return -EFBIG;
-
-	iov_iter_truncate(from, inode->i_sb->s_maxbytes - pos);
+	iov_iter_truncate(from, count);
 	return iov_iter_count(from);
 }
 EXPORT_SYMBOL(generic_write_checks);
@@ -2991,6 +3009,7 @@ int generic_remap_checks(struct file *file_in, loff_t
pos_in,
 	uint64_t bcount;
 	loff_t size_in, size_out;
 	loff_t bs = inode_out->i_sb->s_blocksize;
+	int ret;
 
 	/* The start of both ranges must be aligned to an fs block. */
 	if (!IS_ALIGNED(pos_in, bs) || !IS_ALIGNED(pos_out, bs))
@@ -3014,6 +3033,14 @@ int generic_remap_checks(struct file *file_in, loff_t
pos_in,
 		return -EINVAL;
 	count = min(count, size_in - (uint64_t)pos_in);
 
+	ret = generic_access_check_limits(file_in, pos_in, &count);
+	if (ret)
+		return ret;
+
+	ret = generic_write_check_limits(file_out, pos_out, &count);
+	if (ret)
+		return ret;
+
 	/*
 	 * If the user wanted us to link to the infile's EOF, round up to the
 	 * next block boundary for this check.

From: Darrick J. Wong <darrick.wong at oracle.com>

A deduplication data corruption is exposed in XFS and btrfs. It is
caused by extending the block match range to include the partial EOF
block, but then allowing unknown data beyond EOF to be considered a
"match" to data in the destination file because the comparison is only
made to the end of the source file. This corrupts the destination file
when the source extent is shared with it.

The VFS remapping prep functions  only support whole block dedupe, but
we still need to appear to support whole file dedupe correctly.  Hence
if the dedupe request includes the last block of the souce file, don't
include it in the actual dedupe operation. If the rest of the range
dedupes successfully, then reject the entire request.  A subsequent
patch will enable us to shorten dedupe requests correctly.

When reflinking sub-file ranges, a data corruption can occur when the
source file range includes a partial EOF block. This shares the unknown
data beyond EOF into the second file at a position inside EOF, exposing
stale data in the second file.

If the reflink request includes the last block of the souce file, only
proceed with the reflink operation if it lands at or past the
destination file's current EOF. If it lands within the destination file
EOF, reject the entire request with -EINVAL and make the caller go the
hard way.  A subsequent patch will enable us to shorten reflink requests
correctly.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
Reviewed-by: Christoph Hellwig <hch at lst.de>
---
 fs/read_write.c |   33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)


diff --git a/fs/read_write.c b/fs/read_write.c
index 2456da3f8a41..0f0a6efdd502 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1708,6 +1708,34 @@ static int clone_verify_area(struct file *file, loff_t
pos, u64 len, bool write)
 
 	return security_file_permission(file, write ? MAY_WRITE : MAY_READ);
 }
+/*
+ * Ensure that we don't remap a partial EOF block in the middle of
something
+ * else.  Assume that the offsets have already been checked for block
+ * alignment.
+ *
+ * For deduplication we always scale down to the previous block because we
+ * can't meaningfully compare post-EOF contents.
+ *
+ * For clone we only link a partial EOF block above the destination file's
EOF.
+ */
+static int generic_remap_check_len(struct inode *inode_in,
+				   struct inode *inode_out,
+				   loff_t pos_out,
+				   u64 *len,
+				   bool is_dedupe)
+{
+	u64 blkmask = i_blocksize(inode_in) - 1;
+
+	if ((*len & blkmask) == 0)
+		return 0;
+
+	if (is_dedupe)
+		*len &= ~blkmask;
+	else if (pos_out + *len < i_size_read(inode_out))
+		return -EINVAL;
+
+	return 0;
+}
 
 /*
  * Check that the two inodes are eligible for cloning, the ranges make
@@ -1787,6 +1815,11 @@ int vfs_clone_file_prep(struct file *file_in, loff_t
pos_in,
 			return -EBADE;
 	}
 
+	ret = generic_remap_check_len(inode_in, inode_out, pos_out, len,
+			is_dedupe);
+	if (ret)
+		return ret;
+
 	return 1;
 }
 EXPORT_SYMBOL(vfs_clone_file_prep);

From: Darrick J. Wong <darrick.wong at oracle.com>

Don't bother calling the filesystem for a zero-length dedupe request;
we can return zero and exit.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
Reviewed-by: Christoph Hellwig <hch at lst.de>
Reviewed-by: Amir Goldstein <amir73il at gmail.com>
---
 fs/read_write.c |    5 +++++
 1 file changed, 5 insertions(+)


diff --git a/fs/read_write.c b/fs/read_write.c
index 0f0a6efdd502..f5395d8da741 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -2009,6 +2009,11 @@ int vfs_dedupe_file_range_one(struct file *src_file,
loff_t src_pos,
 	if (!dst_file->f_op->dedupe_file_range)
 		goto out_drop_write;
 
+	if (len == 0) {
+		ret = 0;
+		goto out_drop_write;
+	}
+
 	ret = dst_file->f_op->dedupe_file_range(src_file, src_pos,
 						dst_file, dst_pos, len);
 out_drop_write:

From: Darrick J. Wong <darrick.wong at oracle.com>

The vfs_clone_file_prep is a generic function to be called by filesystem
implementations only.  Rename the prefix to generic_ and make it more
clear that it applies to remap operations, not just clones.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
Reviewed-by: Amir Goldstein <amir73il at gmail.com>
---
 fs/ocfs2/refcounttree.c |    2 +-
 fs/read_write.c         |    8 ++++----
 fs/xfs/xfs_reflink.c    |    2 +-
 include/linux/fs.h      |    6 +++---
 4 files changed, 9 insertions(+), 9 deletions(-)


diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index 19e03936c5e1..36c56dfbe485 100644
--- a/fs/ocfs2/refcounttree.c
+++ b/fs/ocfs2/refcounttree.c
@@ -4850,7 +4850,7 @@ int ocfs2_reflink_remap_range(struct file *file_in,
 	    (OCFS2_I(inode_out)->ip_flags & OCFS2_INODE_SYSTEM_FILE))
 		goto out_unlock;
 
-	ret = vfs_clone_file_prep(file_in, pos_in, file_out, pos_out,
+	ret = generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out,
 			&len, is_dedupe);
 	if (ret <= 0)
 		goto out_unlock;
diff --git a/fs/read_write.c b/fs/read_write.c
index f5395d8da741..aca75a97a695 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1745,9 +1745,9 @@ static int generic_remap_check_len(struct inode *inode_in,
  * Returns: 0 for "nothing to clone", 1 for "something to
clone", or
  * the usual negative error code.
  */
-int vfs_clone_file_prep(struct file *file_in, loff_t pos_in,
-			struct file *file_out, loff_t pos_out,
-			u64 *len, bool is_dedupe)
+int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
+				  struct file *file_out, loff_t pos_out,
+				  u64 *len, bool is_dedupe)
 {
 	struct inode *inode_in = file_inode(file_in);
 	struct inode *inode_out = file_inode(file_out);
@@ -1822,7 +1822,7 @@ int vfs_clone_file_prep(struct file *file_in, loff_t
pos_in,
 
 	return 1;
 }
-EXPORT_SYMBOL(vfs_clone_file_prep);
+EXPORT_SYMBOL(generic_remap_file_range_prep);
 
 int do_clone_file_range(struct file *file_in, loff_t pos_in,
 			struct file *file_out, loff_t pos_out, u64 len)
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 281d5f53f2ec..a7757a128a78 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -1326,7 +1326,7 @@ xfs_reflink_remap_prep(
 	if (IS_DAX(inode_in) || IS_DAX(inode_out))
 		goto out_unlock;
 
-	ret = vfs_clone_file_prep(file_in, pos_in, file_out, pos_out,
+	ret = generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out,
 			len, is_dedupe);
 	if (ret <= 0)
 		goto out_unlock;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index ba93a6e7dac4..55729e1c2e75 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1825,9 +1825,9 @@ extern ssize_t vfs_readv(struct file *, const struct iovec
__user *,
 		unsigned long, loff_t *, rwf_t);
 extern ssize_t vfs_copy_file_range(struct file *, loff_t , struct file *,
 				   loff_t, size_t, unsigned int);
-extern int vfs_clone_file_prep(struct file *file_in, loff_t pos_in,
-			       struct file *file_out, loff_t pos_out,
-			       u64 *count, bool is_dedupe);
+extern int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
+					 struct file *file_out, loff_t pos_out,
+					 u64 *count, bool is_dedupe);
 extern int do_clone_file_range(struct file *file_in, loff_t pos_in,
 			       struct file *file_out, loff_t pos_out, u64 len);
 extern int vfs_clone_file_range(struct file *file_in, loff_t pos_in,

From: Darrick J. Wong <darrick.wong at oracle.com>

Since we use clone_verify_area for both clone and dedupe range checks,
rename the function to make it clear that it's for both.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
Reviewed-by: Amir Goldstein <amir73il at gmail.com>
---
 fs/read_write.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)


diff --git a/fs/read_write.c b/fs/read_write.c
index aca75a97a695..734c5661fb69 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1686,7 +1686,7 @@ SYSCALL_DEFINE6(copy_file_range, int, fd_in, loff_t __user
*, off_in,
 	return ret;
 }
 
-static int clone_verify_area(struct file *file, loff_t pos, u64 len, bool
write)
+static int remap_verify_area(struct file *file, loff_t pos, u64 len, bool
write)
 {
 	struct inode *inode = file_inode(file);
 
@@ -1852,11 +1852,11 @@ int do_clone_file_range(struct file *file_in, loff_t
pos_in,
 	if (!file_in->f_op->clone_file_range)
 		return -EOPNOTSUPP;
 
-	ret = clone_verify_area(file_in, pos_in, len, false);
+	ret = remap_verify_area(file_in, pos_in, len, false);
 	if (ret)
 		return ret;
 
-	ret = clone_verify_area(file_out, pos_out, len, true);
+	ret = remap_verify_area(file_out, pos_out, len, true);
 	if (ret)
 		return ret;
 
@@ -1989,7 +1989,7 @@ int vfs_dedupe_file_range_one(struct file *src_file,
loff_t src_pos,
 	if (ret)
 		return ret;
 
-	ret = clone_verify_area(dst_file, dst_pos, len, true);
+	ret = remap_verify_area(dst_file, dst_pos, len, true);
 	if (ret < 0)
 		goto out_drop_write;
 
@@ -2051,7 +2051,7 @@ int vfs_dedupe_file_range(struct file *file, struct
file_dedupe_range *same)
 	if (!S_ISREG(src->i_mode))
 		goto out;
 
-	ret = clone_verify_area(file, off, len, false);
+	ret = remap_verify_area(file, off, len, false);
 	if (ret < 0)
 		goto out;
 	ret = 0;

From: Darrick J. Wong <darrick.wong at oracle.com>

Combine the clone_file_range and dedupe_file_range operations into a
single remap_file_range file operation dispatch since they're
fundamentally the same operation.  The differences between the two can
be made in the prep functions.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
Reviewed-by: Amir Goldstein <amir73il at gmail.com>
---
 Documentation/filesystems/vfs.txt |   13 +++++------
 fs/btrfs/ctree.h                  |    8 ++-----
 fs/btrfs/file.c                   |    3 +-
 fs/btrfs/ioctl.c                  |   45 +++++++++++++++++++------------------
 fs/cifs/cifsfs.c                  |   22 +++++++++++-------
 fs/nfs/nfs4file.c                 |   10 ++++++--
 fs/ocfs2/file.c                   |   24 +++++++-------------
 fs/overlayfs/file.c               |   30 ++++++++++++++-----------
 fs/read_write.c                   |   18 +++++++--------
 fs/xfs/xfs_file.c                 |   23 ++++++-------------
 include/linux/fs.h                |   20 +++++++++++++---
 11 files changed, 110 insertions(+), 106 deletions(-)


diff --git a/Documentation/filesystems/vfs.txt
b/Documentation/filesystems/vfs.txt
index a6c6a8af48a2..bb3183334ab9 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -883,8 +883,9 @@ struct file_operations {
 	unsigned (*mmap_capabilities)(struct file *);
 #endif
 	ssize_t (*copy_file_range)(struct file *, loff_t, struct file *, loff_t,
size_t, unsigned int);
-	int (*clone_file_range)(struct file *, loff_t, struct file *, loff_t, u64);
-	int (*dedupe_file_range)(struct file *, loff_t, struct file *, loff_t, u64);
+	int (*remap_file_range)(struct file *file_in, loff_t pos_in,
+				struct file *file_out, loff_t pos_out,
+				u64 len, unsigned int remap_flags);
 	int (*fadvise)(struct file *, loff_t, loff_t, int);
 };
 
@@ -960,11 +961,9 @@ otherwise noted.
 
   copy_file_range: called by the copy_file_range(2) system call.
 
-  clone_file_range: called by the ioctl(2) system call for FICLONERANGE and
-	FICLONE commands.
-
-  dedupe_file_range: called by the ioctl(2) system call for FIDEDUPERANGE
-	command.
+  remap_file_range: called by the ioctl(2) system call for FICLONERANGE and
+	FICLONE and FIDEDUPERANGE commands to remap file ranges.  Note that
+	a zero length implies "remap to end of source file".
 
   fadvise: possibly called by the fadvise64() system call.
 
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 2cddfe7806a4..124a05662fc2 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3218,9 +3218,6 @@ void btrfs_get_block_group_info(struct list_head
*groups_list,
 				struct btrfs_ioctl_space_info *space);
 void btrfs_update_ioctl_balance_args(struct btrfs_fs_info *fs_info,
 			       struct btrfs_ioctl_balance_args *bargs);
-int btrfs_dedupe_file_range(struct file *src_file, loff_t src_loff,
-			    struct file *dst_file, loff_t dst_loff,
-			    u64 olen);
 
 /* file.c */
 int __init btrfs_auto_defrag_init(void);
@@ -3250,8 +3247,9 @@ int btrfs_dirty_pages(struct inode *inode, struct page
**pages,
 		      size_t num_pages, loff_t pos, size_t write_bytes,
 		      struct extent_state **cached);
 int btrfs_fdatawrite_range(struct inode *inode, loff_t start, loff_t end);
-int btrfs_clone_file_range(struct file *file_in, loff_t pos_in,
-			   struct file *file_out, loff_t pos_out, u64 len);
+int btrfs_remap_file_range(struct file *file_in, loff_t pos_in,
+			   struct file *file_out, loff_t pos_out, u64 len,
+			   unsigned int remap_flags);
 
 /* tree-defrag.c */
 int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 2be00e873e92..9a963f061393 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -3269,8 +3269,7 @@ const struct file_operations btrfs_file_operations = {
 #ifdef CONFIG_COMPAT
 	.compat_ioctl	= btrfs_compat_ioctl,
 #endif
-	.clone_file_range = btrfs_clone_file_range,
-	.dedupe_file_range = btrfs_dedupe_file_range,
+	.remap_file_range = btrfs_remap_file_range,
 };
 
 void __cold btrfs_auto_defrag_exit(void)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index d60b6caf09e8..bfd99c66723e 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3627,26 +3627,6 @@ static int btrfs_extent_same(struct inode *src, u64 loff,
u64 olen,
 	return ret;
 }
 
-int btrfs_dedupe_file_range(struct file *src_file, loff_t src_loff,
-			    struct file *dst_file, loff_t dst_loff,
-			    u64 olen)
-{
-	struct inode *src = file_inode(src_file);
-	struct inode *dst = file_inode(dst_file);
-	u64 bs = BTRFS_I(src)->root->fs_info->sb->s_blocksize;
-
-	if (WARN_ON_ONCE(bs < PAGE_SIZE)) {
-		/*
-		 * Btrfs does not support blocksize < page_size. As a
-		 * result, btrfs_cmp_data() won't correctly handle
-		 * this situation without an update.
-		 */
-		return -EINVAL;
-	}
-
-	return btrfs_extent_same(src, src_loff, olen, dst, dst_loff);
-}
-
 static int clone_finish_inode_update(struct btrfs_trans_handle *trans,
 				     struct inode *inode,
 				     u64 endoff,
@@ -4348,9 +4328,30 @@ static noinline int btrfs_clone_files(struct file *file,
struct file *file_src,
 	return ret;
 }
 
-int btrfs_clone_file_range(struct file *src_file, loff_t off,
-		struct file *dst_file, loff_t destoff, u64 len)
+int btrfs_remap_file_range(struct file *src_file, loff_t off,
+		struct file *dst_file, loff_t destoff, u64 len,
+		unsigned int remap_flags)
 {
+	if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY))
+		return -EINVAL;
+
+	if (remap_flags & REMAP_FILE_DEDUP) {
+		struct inode *src = file_inode(src_file);
+		struct inode *dst = file_inode(dst_file);
+		u64 bs = BTRFS_I(src)->root->fs_info->sb->s_blocksize;
+
+		if (WARN_ON_ONCE(bs < PAGE_SIZE)) {
+			/*
+			 * Btrfs does not support blocksize < page_size. As a
+			 * result, btrfs_cmp_data() won't correctly handle
+			 * this situation without an update.
+			 */
+			return -EINVAL;
+		}
+
+		return btrfs_extent_same(src, off, len, dst, destoff);
+	}
+
 	return btrfs_clone_files(dst_file, src_file, off, len, destoff);
 }
 
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index 7065426b3280..e8144d0dcde2 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -975,8 +975,9 @@ const struct inode_operations cifs_symlink_inode_ops = {
 	.listxattr = cifs_listxattr,
 };
 
-static int cifs_clone_file_range(struct file *src_file, loff_t off,
-		struct file *dst_file, loff_t destoff, u64 len)
+static int cifs_remap_file_range(struct file *src_file, loff_t off,
+		struct file *dst_file, loff_t destoff, u64 len,
+		unsigned int remap_flags)
 {
 	struct inode *src_inode = file_inode(src_file);
 	struct inode *target_inode = file_inode(dst_file);
@@ -986,6 +987,9 @@ static int cifs_clone_file_range(struct file *src_file,
loff_t off,
 	unsigned int xid;
 	int rc;
 
+	if (remap_flags & ~REMAP_FILE_ADVISORY)
+		return -EINVAL;
+
 	cifs_dbg(FYI, "clone range\n");
 
 	xid = get_xid();
@@ -1134,7 +1138,7 @@ const struct file_operations cifs_file_ops = {
 	.llseek = cifs_llseek,
 	.unlocked_ioctl	= cifs_ioctl,
 	.copy_file_range = cifs_copy_file_range,
-	.clone_file_range = cifs_clone_file_range,
+	.remap_file_range = cifs_remap_file_range,
 	.setlease = cifs_setlease,
 	.fallocate = cifs_fallocate,
 };
@@ -1153,7 +1157,7 @@ const struct file_operations cifs_file_strict_ops = {
 	.llseek = cifs_llseek,
 	.unlocked_ioctl	= cifs_ioctl,
 	.copy_file_range = cifs_copy_file_range,
-	.clone_file_range = cifs_clone_file_range,
+	.remap_file_range = cifs_remap_file_range,
 	.setlease = cifs_setlease,
 	.fallocate = cifs_fallocate,
 };
@@ -1172,7 +1176,7 @@ const struct file_operations cifs_file_direct_ops = {
 	.splice_write = iter_file_splice_write,
 	.unlocked_ioctl  = cifs_ioctl,
 	.copy_file_range = cifs_copy_file_range,
-	.clone_file_range = cifs_clone_file_range,
+	.remap_file_range = cifs_remap_file_range,
 	.llseek = cifs_llseek,
 	.setlease = cifs_setlease,
 	.fallocate = cifs_fallocate,
@@ -1191,7 +1195,7 @@ const struct file_operations cifs_file_nobrl_ops = {
 	.llseek = cifs_llseek,
 	.unlocked_ioctl	= cifs_ioctl,
 	.copy_file_range = cifs_copy_file_range,
-	.clone_file_range = cifs_clone_file_range,
+	.remap_file_range = cifs_remap_file_range,
 	.setlease = cifs_setlease,
 	.fallocate = cifs_fallocate,
 };
@@ -1209,7 +1213,7 @@ const struct file_operations cifs_file_strict_nobrl_ops =
{
 	.llseek = cifs_llseek,
 	.unlocked_ioctl	= cifs_ioctl,
 	.copy_file_range = cifs_copy_file_range,
-	.clone_file_range = cifs_clone_file_range,
+	.remap_file_range = cifs_remap_file_range,
 	.setlease = cifs_setlease,
 	.fallocate = cifs_fallocate,
 };
@@ -1227,7 +1231,7 @@ const struct file_operations cifs_file_direct_nobrl_ops =
{
 	.splice_write = iter_file_splice_write,
 	.unlocked_ioctl  = cifs_ioctl,
 	.copy_file_range = cifs_copy_file_range,
-	.clone_file_range = cifs_clone_file_range,
+	.remap_file_range = cifs_remap_file_range,
 	.llseek = cifs_llseek,
 	.setlease = cifs_setlease,
 	.fallocate = cifs_fallocate,
@@ -1239,7 +1243,7 @@ const struct file_operations cifs_dir_ops = {
 	.read    = generic_read_dir,
 	.unlocked_ioctl  = cifs_ioctl,
 	.copy_file_range = cifs_copy_file_range,
-	.clone_file_range = cifs_clone_file_range,
+	.remap_file_range = cifs_remap_file_range,
 	.llseek = generic_file_llseek,
 	.fsync = cifs_dir_fsync,
 };
diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c
index 4288a6ecaf75..ae5780ce41dc 100644
--- a/fs/nfs/nfs4file.c
+++ b/fs/nfs/nfs4file.c
@@ -180,8 +180,9 @@ static long nfs42_fallocate(struct file *filep, int mode,
loff_t offset, loff_t
 	return nfs42_proc_allocate(filep, offset, len);
 }
 
-static int nfs42_clone_file_range(struct file *src_file, loff_t src_off,
-		struct file *dst_file, loff_t dst_off, u64 count)
+static int nfs42_remap_file_range(struct file *src_file, loff_t src_off,
+		struct file *dst_file, loff_t dst_off, u64 count,
+		unsigned int remap_flags)
 {
 	struct inode *dst_inode = file_inode(dst_file);
 	struct nfs_server *server = NFS_SERVER(dst_inode);
@@ -190,6 +191,9 @@ static int nfs42_clone_file_range(struct file *src_file,
loff_t src_off,
 	bool same_inode = false;
 	int ret;
 
+	if (remap_flags & ~REMAP_FILE_ADVISORY)
+		return -EINVAL;
+
 	/* check alignment w.r.t. clone_blksize */
 	ret = -EINVAL;
 	if (bs) {
@@ -262,7 +266,7 @@ const struct file_operations nfs4_file_operations = {
 	.copy_file_range = nfs4_copy_file_range,
 	.llseek		= nfs4_file_llseek,
 	.fallocate	= nfs42_fallocate,
-	.clone_file_range = nfs42_clone_file_range,
+	.remap_file_range = nfs42_remap_file_range,
 #else
 	.llseek		= nfs_file_llseek,
 #endif
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 9fa35cb6f6e0..0b757a24567c 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2527,24 +2527,18 @@ static loff_t ocfs2_file_llseek(struct file *file,
loff_t offset, int whence)
 	return offset;
 }
 
-static int ocfs2_file_clone_range(struct file *file_in,
+static int ocfs2_remap_file_range(struct file *file_in,
 				  loff_t pos_in,
 				  struct file *file_out,
 				  loff_t pos_out,
-				  u64 len)
+				  u64 len,
+				  unsigned int remap_flags)
 {
-	return ocfs2_reflink_remap_range(file_in, pos_in, file_out, pos_out,
-					 len, false);
-}
+	if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY))
+		return -EINVAL;
 
-static int ocfs2_file_dedupe_range(struct file *file_in,
-				   loff_t pos_in,
-				   struct file *file_out,
-				   loff_t pos_out,
-				   u64 len)
-{
 	return ocfs2_reflink_remap_range(file_in, pos_in, file_out, pos_out,
-					  len, true);
+					 len, remap_flags & REMAP_FILE_DEDUP);
 }
 
 const struct inode_operations ocfs2_file_iops = {
@@ -2586,8 +2580,7 @@ const struct file_operations ocfs2_fops = {
 	.splice_read	= generic_file_splice_read,
 	.splice_write	= iter_file_splice_write,
 	.fallocate	= ocfs2_fallocate,
-	.clone_file_range = ocfs2_file_clone_range,
-	.dedupe_file_range = ocfs2_file_dedupe_range,
+	.remap_file_range = ocfs2_remap_file_range,
 };
 
 const struct file_operations ocfs2_dops = {
@@ -2633,8 +2626,7 @@ const struct file_operations ocfs2_fops_no_plocks = {
 	.splice_read	= generic_file_splice_read,
 	.splice_write	= iter_file_splice_write,
 	.fallocate	= ocfs2_fallocate,
-	.clone_file_range = ocfs2_file_clone_range,
-	.dedupe_file_range = ocfs2_file_dedupe_range,
+	.remap_file_range = ocfs2_remap_file_range,
 };
 
 const struct file_operations ocfs2_dops_no_plocks = {
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index 986313da0c88..fffb36fd5920 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -489,26 +489,31 @@ static ssize_t ovl_copy_file_range(struct file *file_in,
loff_t pos_in,
 			    OVL_COPY);
 }
 
-static int ovl_clone_file_range(struct file *file_in, loff_t pos_in,
-				struct file *file_out, loff_t pos_out, u64 len)
+static int ovl_remap_file_range(struct file *file_in, loff_t pos_in,
+				struct file *file_out, loff_t pos_out,
+				u64 len, unsigned int remap_flags)
 {
-	return ovl_copyfile(file_in, pos_in, file_out, pos_out, len, 0,
-			    OVL_CLONE);
-}
+	enum ovl_copyop op;
+
+	if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY))
+		return -EINVAL;
+
+	if (remap_flags & REMAP_FILE_DEDUP)
+		op = OVL_DEDUPE;
+	else
+		op = OVL_CLONE;
 
-static int ovl_dedupe_file_range(struct file *file_in, loff_t pos_in,
-				 struct file *file_out, loff_t pos_out, u64 len)
-{
 	/*
 	 * Don't copy up because of a dedupe request, this wouldn't make sense
 	 * most of the time (data would be duplicated instead of deduplicated).
 	 */
-	if (!ovl_inode_upper(file_inode(file_in)) ||
-	    !ovl_inode_upper(file_inode(file_out)))
+	if (op == OVL_DEDUPE &&
+	    (!ovl_inode_upper(file_inode(file_in)) ||
+	     !ovl_inode_upper(file_inode(file_out))))
 		return -EPERM;
 
 	return ovl_copyfile(file_in, pos_in, file_out, pos_out, len, 0,
-			    OVL_DEDUPE);
+			    op);
 }
 
 const struct file_operations ovl_file_operations = {
@@ -525,6 +530,5 @@ const struct file_operations ovl_file_operations = {
 	.compat_ioctl	= ovl_compat_ioctl,
 
 	.copy_file_range	= ovl_copy_file_range,
-	.clone_file_range	= ovl_clone_file_range,
-	.dedupe_file_range	= ovl_dedupe_file_range,
+	.remap_file_range	= ovl_remap_file_range,
 };
diff --git a/fs/read_write.c b/fs/read_write.c
index 734c5661fb69..766bdcb381f3 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1588,9 +1588,9 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t
pos_in,
 	 * Try cloning first, this is supported by more file systems, and
 	 * more efficient if both clone and copy are supported (e.g. NFS).
 	 */
-	if (file_in->f_op->clone_file_range) {
-		ret = file_in->f_op->clone_file_range(file_in, pos_in,
-				file_out, pos_out, len);
+	if (file_in->f_op->remap_file_range) {
+		ret = file_in->f_op->remap_file_range(file_in, pos_in,
+				file_out, pos_out, len, 0);
 		if (ret == 0) {
 			ret = len;
 			goto done;
@@ -1849,7 +1849,7 @@ int do_clone_file_range(struct file *file_in, loff_t
pos_in,
 	    (file_out->f_flags & O_APPEND))
 		return -EBADF;
 
-	if (!file_in->f_op->clone_file_range)
+	if (!file_in->f_op->remap_file_range)
 		return -EOPNOTSUPP;
 
 	ret = remap_verify_area(file_in, pos_in, len, false);
@@ -1860,8 +1860,8 @@ int do_clone_file_range(struct file *file_in, loff_t
pos_in,
 	if (ret)
 		return ret;
 
-	ret = file_in->f_op->clone_file_range(file_in, pos_in,
-			file_out, pos_out, len);
+	ret = file_in->f_op->remap_file_range(file_in, pos_in,
+			file_out, pos_out, len, 0);
 	if (!ret) {
 		fsnotify_access(file_in);
 		fsnotify_modify(file_out);
@@ -2006,7 +2006,7 @@ int vfs_dedupe_file_range_one(struct file *src_file,
loff_t src_pos,
 		goto out_drop_write;
 
 	ret = -EINVAL;
-	if (!dst_file->f_op->dedupe_file_range)
+	if (!dst_file->f_op->remap_file_range)
 		goto out_drop_write;
 
 	if (len == 0) {
@@ -2014,8 +2014,8 @@ int vfs_dedupe_file_range_one(struct file *src_file,
loff_t src_pos,
 		goto out_drop_write;
 	}
 
-	ret = dst_file->f_op->dedupe_file_range(src_file, src_pos,
-						dst_file, dst_pos, len);
+	ret = dst_file->f_op->remap_file_range(src_file, src_pos, dst_file,
+			dst_pos, len, REMAP_FILE_DEDUP);
 out_drop_write:
 	mnt_drop_write_file(dst_file);
 
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 61a5ad2600e8..2ad94d508f80 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -920,27 +920,19 @@ xfs_file_fallocate(
 }
 
 STATIC int
-xfs_file_clone_range(
+xfs_file_remap_range(
 	struct file	*file_in,
 	loff_t		pos_in,
 	struct file	*file_out,
 	loff_t		pos_out,
-	u64		len)
+	u64		len,
+	unsigned int	remap_flags)
 {
-	return xfs_reflink_remap_range(file_in, pos_in, file_out, pos_out,
-				     len, false);
-}
+	if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY))
+		return -EINVAL;
 
-STATIC int
-xfs_file_dedupe_range(
-	struct file	*file_in,
-	loff_t		pos_in,
-	struct file	*file_out,
-	loff_t		pos_out,
-	u64		len)
-{
 	return xfs_reflink_remap_range(file_in, pos_in, file_out, pos_out,
-				     len, true);
+			len, remap_flags & REMAP_FILE_DEDUP);
 }
 
 STATIC int
@@ -1175,8 +1167,7 @@ const struct file_operations xfs_file_operations = {
 	.fsync		= xfs_file_fsync,
 	.get_unmapped_area = thp_get_unmapped_area,
 	.fallocate	= xfs_file_fallocate,
-	.clone_file_range = xfs_file_clone_range,
-	.dedupe_file_range = xfs_file_dedupe_range,
+	.remap_file_range = xfs_file_remap_range,
 };
 
 const struct file_operations xfs_dir_file_operations = {
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 55729e1c2e75..794d1b83eded 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1721,6 +1721,19 @@ struct block_device_operations;
 #define NOMMU_VMFLAGS \
 	(NOMMU_MAP_READ | NOMMU_MAP_WRITE | NOMMU_MAP_EXEC)
 
+/*
+ * These flags control the behavior of the remap_file_range function pointer.
+ * If it is called with len == 0 that means "remap to end of source
file".
+ *
+ * REMAP_FILE_DEDUP: only remap if contents identical (i.e. deduplicate)
+ */
+#define REMAP_FILE_DEDUP		(1 << 0)
+
+/* All valid REMAP_FILE flags */
+#define REMAP_FILE_VALID_FLAGS		(REMAP_FILE_DEDUP)
+
+/* REMAP_FILE flags taken care of by the vfs. */
+#define REMAP_FILE_ADVISORY		(0)
 
 struct iov_iter;
 
@@ -1759,10 +1772,9 @@ struct file_operations {
 #endif
 	ssize_t (*copy_file_range)(struct file *, loff_t, struct file *,
 			loff_t, size_t, unsigned int);
-	int (*clone_file_range)(struct file *, loff_t, struct file *, loff_t,
-			u64);
-	int (*dedupe_file_range)(struct file *, loff_t, struct file *, loff_t,
-			u64);
+	int (*remap_file_range)(struct file *file_in, loff_t pos_in,
+				struct file *file_out, loff_t pos_out,
+				u64 len, unsigned int remap_flags);
 	int (*fadvise)(struct file *, loff_t, loff_t, int);
 } __randomize_layout;

From: Darrick J. Wong <darrick.wong at oracle.com>

Plumb the remap flags through the filesystem from the vfs function
dispatcher all the way to the prep function to prepare for behavior
changes in subsequent patches.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
Reviewed-by: Amir Goldstein <amir73il at gmail.com>
---
 fs/ocfs2/file.c         |    2 +-
 fs/ocfs2/refcounttree.c |    4 ++--
 fs/ocfs2/refcounttree.h |    2 +-
 fs/read_write.c         |   14 +++++++-------
 fs/xfs/xfs_file.c       |    2 +-
 fs/xfs/xfs_reflink.c    |   21 +++++++++++----------
 fs/xfs/xfs_reflink.h    |    3 ++-
 include/linux/fs.h      |    2 +-
 8 files changed, 26 insertions(+), 24 deletions(-)


diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 0b757a24567c..9809b0e5746f 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2538,7 +2538,7 @@ static int ocfs2_remap_file_range(struct file *file_in,
 		return -EINVAL;
 
 	return ocfs2_reflink_remap_range(file_in, pos_in, file_out, pos_out,
-					 len, remap_flags & REMAP_FILE_DEDUP);
+					 len, remap_flags);
 }
 
 const struct inode_operations ocfs2_file_iops = {
diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index 36c56dfbe485..df9781567ec0 100644
--- a/fs/ocfs2/refcounttree.c
+++ b/fs/ocfs2/refcounttree.c
@@ -4825,7 +4825,7 @@ int ocfs2_reflink_remap_range(struct file *file_in,
 			      struct file *file_out,
 			      loff_t pos_out,
 			      u64 len,
-			      bool is_dedupe)
+			      unsigned int remap_flags)
 {
 	struct inode *inode_in = file_inode(file_in);
 	struct inode *inode_out = file_inode(file_out);
@@ -4851,7 +4851,7 @@ int ocfs2_reflink_remap_range(struct file *file_in,
 		goto out_unlock;
 
 	ret = generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out,
-			&len, is_dedupe);
+			&len, remap_flags);
 	if (ret <= 0)
 		goto out_unlock;
 
diff --git a/fs/ocfs2/refcounttree.h b/fs/ocfs2/refcounttree.h
index 4af55bf4b35b..d2c5f526edff 100644
--- a/fs/ocfs2/refcounttree.h
+++ b/fs/ocfs2/refcounttree.h
@@ -120,6 +120,6 @@ int ocfs2_reflink_remap_range(struct file *file_in,
 			      struct file *file_out,
 			      loff_t pos_out,
 			      u64 len,
-			      bool is_dedupe);
+			      unsigned int remap_flags);
 
 #endif /* OCFS2_REFCOUNTTREE_H */
diff --git a/fs/read_write.c b/fs/read_write.c
index 766bdcb381f3..201381689284 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1722,14 +1722,14 @@ static int generic_remap_check_len(struct inode
*inode_in,
 				   struct inode *inode_out,
 				   loff_t pos_out,
 				   u64 *len,
-				   bool is_dedupe)
+				   unsigned int remap_flags)
 {
 	u64 blkmask = i_blocksize(inode_in) - 1;
 
 	if ((*len & blkmask) == 0)
 		return 0;
 
-	if (is_dedupe)
+	if (remap_flags & REMAP_FILE_DEDUP)
 		*len &= ~blkmask;
 	else if (pos_out + *len < i_size_read(inode_out))
 		return -EINVAL;
@@ -1747,7 +1747,7 @@ static int generic_remap_check_len(struct inode *inode_in,
  */
 int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
 				  struct file *file_out, loff_t pos_out,
-				  u64 *len, bool is_dedupe)
+				  u64 *len, unsigned int remap_flags)
 {
 	struct inode *inode_in = file_inode(file_in);
 	struct inode *inode_out = file_inode(file_out);
@@ -1771,7 +1771,7 @@ int generic_remap_file_range_prep(struct file *file_in,
loff_t pos_in,
 	if (*len == 0) {
 		loff_t isize = i_size_read(inode_in);
 
-		if (is_dedupe || pos_in == isize)
+		if ((remap_flags & REMAP_FILE_DEDUP) || pos_in == isize)
 			return 0;
 		if (pos_in > isize)
 			return -EINVAL;
@@ -1782,7 +1782,7 @@ int generic_remap_file_range_prep(struct file *file_in,
loff_t pos_in,
 
 	/* Check that we don't violate system file offset limits. */
 	ret = generic_remap_checks(file_in, pos_in, file_out, pos_out, len,
-			is_dedupe);
+			(remap_flags & REMAP_FILE_DEDUP));
 	if (ret)
 		return ret;
 
@@ -1804,7 +1804,7 @@ int generic_remap_file_range_prep(struct file *file_in,
loff_t pos_in,
 	/*
 	 * Check that the extents are the same.
 	 */
-	if (is_dedupe) {
+	if (remap_flags & REMAP_FILE_DEDUP) {
 		bool		is_same = false;
 
 		ret = vfs_dedupe_file_range_compare(inode_in, pos_in,
@@ -1816,7 +1816,7 @@ int generic_remap_file_range_prep(struct file *file_in,
loff_t pos_in,
 	}
 
 	ret = generic_remap_check_len(inode_in, inode_out, pos_out, len,
-			is_dedupe);
+			remap_flags);
 	if (ret)
 		return ret;
 
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 2ad94d508f80..20314eb4677a 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -932,7 +932,7 @@ xfs_file_remap_range(
 		return -EINVAL;
 
 	return xfs_reflink_remap_range(file_in, pos_in, file_out, pos_out,
-			len, remap_flags & REMAP_FILE_DEDUP);
+			len, remap_flags);
 }
 
 STATIC int
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index a7757a128a78..29aab196ce7e 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -921,13 +921,14 @@ xfs_reflink_update_dest(
 	struct xfs_inode	*dest,
 	xfs_off_t		newlen,
 	xfs_extlen_t		cowextsize,
-	bool			is_dedupe)
+	unsigned int		remap_flags)
 {
 	struct xfs_mount	*mp = dest->i_mount;
 	struct xfs_trans	*tp;
 	int			error;
 
-	if (is_dedupe && newlen <= i_size_read(VFS_I(dest)) &&
cowextsize == 0)
+	if ((remap_flags & REMAP_FILE_DEDUP) &&
+	    newlen <= i_size_read(VFS_I(dest)) && cowextsize == 0)
 		return 0;
 
 	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
@@ -948,7 +949,7 @@ xfs_reflink_update_dest(
 		dest->i_d.di_flags2 |= XFS_DIFLAG2_COWEXTSIZE;
 	}
 
-	if (!is_dedupe) {
+	if (!(remap_flags & REMAP_FILE_DEDUP)) {
 		xfs_trans_ichgtime(tp, dest,
 				   XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
 	}
@@ -1296,7 +1297,7 @@ xfs_reflink_remap_prep(
 	struct file		*file_out,
 	loff_t			pos_out,
 	u64			*len,
-	bool			is_dedupe)
+	unsigned int		remap_flags)
 {
 	struct inode		*inode_in = file_inode(file_in);
 	struct xfs_inode	*src = XFS_I(inode_in);
@@ -1327,7 +1328,7 @@ xfs_reflink_remap_prep(
 		goto out_unlock;
 
 	ret = generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out,
-			len, is_dedupe);
+			len, remap_flags);
 	if (ret <= 0)
 		goto out_unlock;
 
@@ -1336,7 +1337,7 @@ xfs_reflink_remap_prep(
 	 * from the source file so we don't try to dedupe the partial
 	 * EOF block.
 	 */
-	if (is_dedupe) {
+	if (remap_flags & REMAP_FILE_DEDUP) {
 		*len &= ~blkmask;
 	} else if (*len & blkmask) {
 		/*
@@ -1372,7 +1373,7 @@ xfs_reflink_remap_prep(
 				   PAGE_ALIGN(pos_out + *len) - 1);
 
 	/* If we're altering the file contents... */
-	if (!is_dedupe) {
+	if (!(remap_flags & REMAP_FILE_DEDUP)) {
 		/*
 		 * ...update the timestamps (which will grab the ilock again
 		 * from xfs_fs_dirty_inode, so we have to call it before we
@@ -1410,7 +1411,7 @@ xfs_reflink_remap_range(
 	struct file		*file_out,
 	loff_t			pos_out,
 	u64			len,
-	bool			is_dedupe)
+	unsigned int		remap_flags)
 {
 	struct inode		*inode_in = file_inode(file_in);
 	struct xfs_inode	*src = XFS_I(inode_in);
@@ -1430,7 +1431,7 @@ xfs_reflink_remap_range(
 
 	/* Prepare and then clone file data. */
 	ret = xfs_reflink_remap_prep(file_in, pos_in, file_out, pos_out,
-			&len, is_dedupe);
+			&len, remap_flags);
 	if (ret <= 0)
 		return ret;
 
@@ -1457,7 +1458,7 @@ xfs_reflink_remap_range(
 		cowextsize = src->i_d.di_cowextsize;
 
 	ret = xfs_reflink_update_dest(dest, pos_out + len, cowextsize,
-			is_dedupe);
+			remap_flags);
 
 out_unlock:
 	xfs_reflink_remap_unlock(file_in, file_out);
diff --git a/fs/xfs/xfs_reflink.h b/fs/xfs/xfs_reflink.h
index c585ad9552b2..6f82d628bf17 100644
--- a/fs/xfs/xfs_reflink.h
+++ b/fs/xfs/xfs_reflink.h
@@ -28,7 +28,8 @@ extern int xfs_reflink_end_cow(struct xfs_inode *ip, xfs_off_t
offset,
 		xfs_off_t count);
 extern int xfs_reflink_recover_cow(struct xfs_mount *mp);
 extern int xfs_reflink_remap_range(struct file *file_in, loff_t pos_in,
-		struct file *file_out, loff_t pos_out, u64 len, bool is_dedupe);
+		struct file *file_out, loff_t pos_out, u64 len,
+		unsigned int remap_flags);
 extern int xfs_reflink_inode_has_shared_extents(struct xfs_trans *tp,
 		struct xfs_inode *ip, bool *has_shared);
 extern int xfs_reflink_clear_inode_flag(struct xfs_inode *ip,
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 794d1b83eded..c2800953937a 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1839,7 +1839,7 @@ extern ssize_t vfs_copy_file_range(struct file *, loff_t ,
struct file *,
 				   loff_t, size_t, unsigned int);
 extern int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
 					 struct file *file_out, loff_t pos_out,
-					 u64 *count, bool is_dedupe);
+					 u64 *count, unsigned int remap_flags);
 extern int do_clone_file_range(struct file *file_in, loff_t pos_in,
 			       struct file *file_out, loff_t pos_out, u64 len);
 extern int vfs_clone_file_range(struct file *file_in, loff_t pos_in,

From: Darrick J. Wong <darrick.wong at oracle.com>

Pass the same remap flags to generic_remap_checks for consistency.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
Reviewed-by: Amir Goldstein <amir73il at gmail.com>
---
 fs/read_write.c    |    2 +-
 include/linux/fs.h |    2 +-
 mm/filemap.c       |    4 ++--
 3 files changed, 4 insertions(+), 4 deletions(-)


diff --git a/fs/read_write.c b/fs/read_write.c
index 201381689284..ebcbfc4f2907 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1782,7 +1782,7 @@ int generic_remap_file_range_prep(struct file *file_in,
loff_t pos_in,
 
 	/* Check that we don't violate system file offset limits. */
 	ret = generic_remap_checks(file_in, pos_in, file_out, pos_out, len,
-			(remap_flags & REMAP_FILE_DEDUP));
+			remap_flags);
 	if (ret)
 		return ret;
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index c2800953937a..1aa3bc1bb092 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2981,7 +2981,7 @@ extern int generic_file_readonly_mmap(struct file *,
struct vm_area_struct *);
 extern ssize_t generic_write_checks(struct kiocb *, struct iov_iter *);
 extern int generic_remap_checks(struct file *file_in, loff_t pos_in,
 				struct file *file_out, loff_t pos_out,
-				uint64_t *count, bool is_dedupe);
+				uint64_t *count, unsigned int remap_flags);
 extern ssize_t generic_file_read_iter(struct kiocb *, struct iov_iter *);
 extern ssize_t __generic_file_write_iter(struct kiocb *, struct iov_iter *);
 extern ssize_t generic_file_write_iter(struct kiocb *, struct iov_iter *);
diff --git a/mm/filemap.c b/mm/filemap.c
index 08ad210fee49..b0f1f6d93d9c 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3001,7 +3001,7 @@ EXPORT_SYMBOL(generic_write_checks);
  */
 int generic_remap_checks(struct file *file_in, loff_t pos_in,
 			 struct file *file_out, loff_t pos_out,
-			 uint64_t *req_count, bool is_dedupe)
+			 uint64_t *req_count, unsigned int remap_flags)
 {
 	struct inode *inode_in = file_in->f_mapping->host;
 	struct inode *inode_out = file_out->f_mapping->host;
@@ -3023,7 +3023,7 @@ int generic_remap_checks(struct file *file_in, loff_t
pos_in,
 	size_out = i_size_read(inode_out);
 
 	/* Dedupe requires both ranges to be within EOF. */
-	if (is_dedupe &&
+	if ((remap_flags & REMAP_FILE_DEDUP) &&
 	    (pos_in >= size_in || pos_in + count > size_in ||
 	     pos_out >= size_out || pos_out + count > size_out))
 		return -EINVAL;

From: Darrick J. Wong <darrick.wong at oracle.com>

Create a new VFS helper to handle inode metadata updates when remapping
into a file.  If the operation can possibly alter the file contents, we
must update the ctime and mtime and remove security privileges, just
like we do for regular file writes.  Wire up ocfs2 to ensure consistent
behavior.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
Reviewed-by: Amir Goldstein <amir73il at gmail.com>
---
 fs/read_write.c      |   28 ++++++++++++++++++++++++++++
 fs/xfs/xfs_reflink.c |   23 -----------------------
 2 files changed, 28 insertions(+), 23 deletions(-)


diff --git a/fs/read_write.c b/fs/read_write.c
index ebcbfc4f2907..3f6392f1d5d4 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1737,6 +1737,30 @@ static int generic_remap_check_len(struct inode
*inode_in,
 	return 0;
 }
 
+/* Update inode timestamps and remove security privileges when remapping. */
+static int generic_remap_file_range_target(struct file *file,
+					   unsigned int remap_flags)
+{
+	int ret;
+
+	/* If can't alter the file contents, we're done. */
+	if (remap_flags & REMAP_FILE_DEDUP)
+		return 0;
+
+	/* Update the timestamps, since we can alter file contents. */
+	if (!(file->f_mode & FMODE_NOCMTIME)) {
+		ret = file_update_time(file);
+		if (ret)
+			return ret;
+	}
+
+	/*
+	 * Clear the security bits if the process is not being run by root.
+	 * This keeps people from modifying setuid and setgid binaries.
+	 */
+	return file_remove_privs(file);
+}
+
 /*
  * Check that the two inodes are eligible for cloning, the ranges make
  * sense, and then flush all dirty data.  Caller must ensure that the
@@ -1820,6 +1844,10 @@ int generic_remap_file_range_prep(struct file *file_in,
loff_t pos_in,
 	if (ret)
 		return ret;
 
+	ret = generic_remap_file_range_target(file_out, remap_flags);
+	if (ret)
+		return ret;
+
 	return 1;
 }
 EXPORT_SYMBOL(generic_remap_file_range_prep);
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 29aab196ce7e..2d7dd8b28d7c 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -1372,29 +1372,6 @@ xfs_reflink_remap_prep(
 	truncate_inode_pages_range(&inode_out->i_data, pos_out,
 				   PAGE_ALIGN(pos_out + *len) - 1);
 
-	/* If we're altering the file contents... */
-	if (!(remap_flags & REMAP_FILE_DEDUP)) {
-		/*
-		 * ...update the timestamps (which will grab the ilock again
-		 * from xfs_fs_dirty_inode, so we have to call it before we
-		 * take the ilock).
-		 */
-		if (!(file_out->f_mode & FMODE_NOCMTIME)) {
-			ret = file_update_time(file_out);
-			if (ret)
-				goto out_unlock;
-		}
-
-		/*
-		 * ...clear the security bits if the process is not being run
-		 * by root.  This keeps people from modifying setuid and setgid
-		 * binaries.
-		 */
-		ret = file_remove_privs(file_out);
-		if (ret)
-			goto out_unlock;
-	}
-
 	return 1;
 out_unlock:
 	xfs_reflink_remap_unlock(file_in, file_out);

From: Darrick J. Wong <darrick.wong at oracle.com>

Change the remap_file_range functions to take a number of bytes to
operate upon and return the number of bytes they operated on.  This is a
requirement for allowing fs implementations to return short clone/dedupe
results to the user, which will enable us to obey resource limits in a
graceful manner.

A subsequent patch will enable copy_file_range to signal to the
->clone_file_range implementation that it can handle a short length,
which will be returned in the function's return value.  For now the
short return is not implemented anywhere so the behavior won't change --
either copy_file_range manages to clone the entire range or it tries an
alternative.

Neither clone ioctl can take advantage of this, alas.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
Reviewed-by: Amir Goldstein <amir73il at gmail.com>
---
 Documentation/filesystems/vfs.txt |    6 ++---
 fs/btrfs/ctree.h                  |    6 ++---
 fs/btrfs/ioctl.c                  |   13 ++++++----
 fs/cifs/cifsfs.c                  |    6 ++---
 fs/ioctl.c                        |   10 +++++++-
 fs/nfs/nfs4file.c                 |    6 ++---
 fs/nfsd/vfs.c                     |    8 +++++-
 fs/ocfs2/file.c                   |   16 ++++++------
 fs/ocfs2/refcounttree.c           |    2 +-
 fs/ocfs2/refcounttree.h           |    2 +-
 fs/overlayfs/copy_up.c            |    6 ++---
 fs/overlayfs/file.c               |   12 +++++----
 fs/read_write.c                   |   49 ++++++++++++++++++++-----------------
 fs/xfs/xfs_file.c                 |    9 +++++--
 fs/xfs/xfs_reflink.c              |    4 ++-
 fs/xfs/xfs_reflink.h              |    2 +-
 include/linux/fs.h                |   27 +++++++++++---------
 mm/filemap.c                      |    2 +-
 18 files changed, 106 insertions(+), 80 deletions(-)


diff --git a/Documentation/filesystems/vfs.txt
b/Documentation/filesystems/vfs.txt
index bb3183334ab9..8ba47d9d6cae 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -883,9 +883,9 @@ struct file_operations {
 	unsigned (*mmap_capabilities)(struct file *);
 #endif
 	ssize_t (*copy_file_range)(struct file *, loff_t, struct file *, loff_t,
size_t, unsigned int);
-	int (*remap_file_range)(struct file *file_in, loff_t pos_in,
-				struct file *file_out, loff_t pos_out,
-				u64 len, unsigned int remap_flags);
+	loff_t (*remap_file_range)(struct file *file_in, loff_t pos_in,
+				   struct file *file_out, loff_t pos_out,
+				   loff_t len, unsigned int remap_flags);
 	int (*fadvise)(struct file *, loff_t, loff_t, int);
 };
 
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 124a05662fc2..771a961d77ad 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3247,9 +3247,9 @@ int btrfs_dirty_pages(struct inode *inode, struct page
**pages,
 		      size_t num_pages, loff_t pos, size_t write_bytes,
 		      struct extent_state **cached);
 int btrfs_fdatawrite_range(struct inode *inode, loff_t start, loff_t end);
-int btrfs_remap_file_range(struct file *file_in, loff_t pos_in,
-			   struct file *file_out, loff_t pos_out, u64 len,
-			   unsigned int remap_flags);
+loff_t btrfs_remap_file_range(struct file *file_in, loff_t pos_in,
+			      struct file *file_out, loff_t pos_out,
+			      loff_t len, unsigned int remap_flags);
 
 /* tree-defrag.c */
 int btrfs_defrag_leaves(struct btrfs_trans_handle *trans,
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index bfd99c66723e..b0c513e10977 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -4328,10 +4328,12 @@ static noinline int btrfs_clone_files(struct file *file,
struct file *file_src,
 	return ret;
 }
 
-int btrfs_remap_file_range(struct file *src_file, loff_t off,
-		struct file *dst_file, loff_t destoff, u64 len,
+loff_t btrfs_remap_file_range(struct file *src_file, loff_t off,
+		struct file *dst_file, loff_t destoff, loff_t len,
 		unsigned int remap_flags)
 {
+	int ret;
+
 	if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY))
 		return -EINVAL;
 
@@ -4349,10 +4351,11 @@ int btrfs_remap_file_range(struct file *src_file, loff_t
off,
 			return -EINVAL;
 		}
 
-		return btrfs_extent_same(src, off, len, dst, destoff);
+		ret = btrfs_extent_same(src, off, len, dst, destoff);
+	} else {
+		ret = btrfs_clone_files(dst_file, src_file, off, len, destoff);
 	}
-
-	return btrfs_clone_files(dst_file, src_file, off, len, destoff);
+	return ret < 0 ? ret : len;
 }
 
 static long btrfs_ioctl_default_subvol(struct file *file, void __user *argp)
diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index e8144d0dcde2..5ca71c6c8be2 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -975,8 +975,8 @@ const struct inode_operations cifs_symlink_inode_ops = {
 	.listxattr = cifs_listxattr,
 };
 
-static int cifs_remap_file_range(struct file *src_file, loff_t off,
-		struct file *dst_file, loff_t destoff, u64 len,
+static loff_t cifs_remap_file_range(struct file *src_file, loff_t off,
+		struct file *dst_file, loff_t destoff, loff_t len,
 		unsigned int remap_flags)
 {
 	struct inode *src_inode = file_inode(src_file);
@@ -1029,7 +1029,7 @@ static int cifs_remap_file_range(struct file *src_file,
loff_t off,
 	unlock_two_nondirectories(src_inode, target_inode);
 out:
 	free_xid(xid);
-	return rc;
+	return rc < 0 ? rc : len;
 }
 
 ssize_t cifs_file_copychunk_range(unsigned int xid,
diff --git a/fs/ioctl.c b/fs/ioctl.c
index 2005529af560..72537b68c272 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -223,6 +223,7 @@ static long ioctl_file_clone(struct file *dst_file, unsigned
long srcfd,
 			     u64 off, u64 olen, u64 destoff)
 {
 	struct fd src_file = fdget(srcfd);
+	loff_t cloned;
 	int ret;
 
 	if (!src_file.file)
@@ -230,7 +231,14 @@ static long ioctl_file_clone(struct file *dst_file,
unsigned long srcfd,
 	ret = -EXDEV;
 	if (src_file.file->f_path.mnt != dst_file->f_path.mnt)
 		goto fdput;
-	ret = vfs_clone_file_range(src_file.file, off, dst_file, destoff, olen);
+	cloned = vfs_clone_file_range(src_file.file, off, dst_file, destoff,
+				      olen);
+	if (cloned < 0)
+		ret = cloned;
+	else if (olen && cloned != olen)
+		ret = -EINVAL;
+	else
+		ret = 0;
 fdput:
 	fdput(src_file);
 	return ret;
diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c
index ae5780ce41dc..46d691ba04bc 100644
--- a/fs/nfs/nfs4file.c
+++ b/fs/nfs/nfs4file.c
@@ -180,8 +180,8 @@ static long nfs42_fallocate(struct file *filep, int mode,
loff_t offset, loff_t
 	return nfs42_proc_allocate(filep, offset, len);
 }
 
-static int nfs42_remap_file_range(struct file *src_file, loff_t src_off,
-		struct file *dst_file, loff_t dst_off, u64 count,
+static loff_t nfs42_remap_file_range(struct file *src_file, loff_t src_off,
+		struct file *dst_file, loff_t dst_off, loff_t count,
 		unsigned int remap_flags)
 {
 	struct inode *dst_inode = file_inode(dst_file);
@@ -244,7 +244,7 @@ static int nfs42_remap_file_range(struct file *src_file,
loff_t src_off,
 		inode_unlock(src_inode);
 	}
 out:
-	return ret;
+	return ret < 0 ? ret : count;
 }
 #endif /* CONFIG_NFS_V4_2 */
 
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index b53e76391e52..ac6cb6101cbe 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -541,8 +541,12 @@ __be32 nfsd4_set_nfs4_label(struct svc_rqst *rqstp, struct
svc_fh *fhp,
 __be32 nfsd4_clone_file_range(struct file *src, u64 src_pos, struct file *dst,
 		u64 dst_pos, u64 count)
 {
-	return nfserrno(vfs_clone_file_range(src, src_pos, dst, dst_pos,
-					     count));
+	loff_t cloned;
+
+	cloned = vfs_clone_file_range(src, src_pos, dst, dst_pos, count);
+	if (count && cloned != count)
+		cloned = -EINVAL;
+	return nfserrno(cloned < 0 ? cloned : 0);
 }
 
 ssize_t nfsd_copy_file_range(struct file *src, u64 src_pos, struct file *dst,
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 9809b0e5746f..fbaeafe44b5f 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2527,18 +2527,18 @@ static loff_t ocfs2_file_llseek(struct file *file,
loff_t offset, int whence)
 	return offset;
 }
 
-static int ocfs2_remap_file_range(struct file *file_in,
-				  loff_t pos_in,
-				  struct file *file_out,
-				  loff_t pos_out,
-				  u64 len,
-				  unsigned int remap_flags)
+static loff_t ocfs2_remap_file_range(struct file *file_in, loff_t pos_in,
+				     struct file *file_out, loff_t pos_out,
+				     loff_t len, unsigned int remap_flags)
 {
+	int ret;
+
 	if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY))
 		return -EINVAL;
 
-	return ocfs2_reflink_remap_range(file_in, pos_in, file_out, pos_out,
-					 len, remap_flags);
+	ret = ocfs2_reflink_remap_range(file_in, pos_in, file_out, pos_out,
+					len, remap_flags);
+	return ret < 0 ? ret : len;
 }
 
 const struct inode_operations ocfs2_file_iops = {
diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index df9781567ec0..6a42c04ac0ab 100644
--- a/fs/ocfs2/refcounttree.c
+++ b/fs/ocfs2/refcounttree.c
@@ -4824,7 +4824,7 @@ int ocfs2_reflink_remap_range(struct file *file_in,
 			      loff_t pos_in,
 			      struct file *file_out,
 			      loff_t pos_out,
-			      u64 len,
+			      loff_t len,
 			      unsigned int remap_flags)
 {
 	struct inode *inode_in = file_inode(file_in);
diff --git a/fs/ocfs2/refcounttree.h b/fs/ocfs2/refcounttree.h
index d2c5f526edff..eb65c1d0843c 100644
--- a/fs/ocfs2/refcounttree.h
+++ b/fs/ocfs2/refcounttree.h
@@ -119,7 +119,7 @@ int ocfs2_reflink_remap_range(struct file *file_in,
 			      loff_t pos_in,
 			      struct file *file_out,
 			      loff_t pos_out,
-			      u64 len,
+			      loff_t len,
 			      unsigned int remap_flags);
 
 #endif /* OCFS2_REFCOUNTTREE_H */
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index 1cc797a08a5b..8750b7235516 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -125,6 +125,7 @@ static int ovl_copy_up_data(struct path *old, struct path
*new, loff_t len)
 	struct file *new_file;
 	loff_t old_pos = 0;
 	loff_t new_pos = 0;
+	loff_t cloned;
 	int error = 0;
 
 	if (len == 0)
@@ -141,11 +142,10 @@ static int ovl_copy_up_data(struct path *old, struct path
*new, loff_t len)
 	}
 
 	/* Try to use clone_file_range to clone up within the same fs */
-	error = do_clone_file_range(old_file, 0, new_file, 0, len);
-	if (!error)
+	cloned = do_clone_file_range(old_file, 0, new_file, 0, len);
+	if (cloned == len)
 		goto out;
 	/* Couldn't clone, so now we try to copy the data */
-	error = 0;
 
 	/* FIXME: copy up sparse files efficiently */
 	while (len) {
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index fffb36fd5920..6c3fec6168e9 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -434,14 +434,14 @@ enum ovl_copyop {
 	OVL_DEDUPE,
 };
 
-static ssize_t ovl_copyfile(struct file *file_in, loff_t pos_in,
+static loff_t ovl_copyfile(struct file *file_in, loff_t pos_in,
 			    struct file *file_out, loff_t pos_out,
-			    u64 len, unsigned int flags, enum ovl_copyop op)
+			    loff_t len, unsigned int flags, enum ovl_copyop op)
 {
 	struct inode *inode_out = file_inode(file_out);
 	struct fd real_in, real_out;
 	const struct cred *old_cred;
-	ssize_t ret;
+	loff_t ret;
 
 	ret = ovl_real_fdget(file_out, &real_out);
 	if (ret)
@@ -489,9 +489,9 @@ static ssize_t ovl_copy_file_range(struct file *file_in,
loff_t pos_in,
 			    OVL_COPY);
 }
 
-static int ovl_remap_file_range(struct file *file_in, loff_t pos_in,
-				struct file *file_out, loff_t pos_out,
-				u64 len, unsigned int remap_flags)
+static loff_t ovl_remap_file_range(struct file *file_in, loff_t pos_in,
+				   struct file *file_out, loff_t pos_out,
+				   loff_t len, unsigned int remap_flags)
 {
 	enum ovl_copyop op;
 
diff --git a/fs/read_write.c b/fs/read_write.c
index 3f6392f1d5d4..906e78be5001 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1589,10 +1589,13 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t
pos_in,
 	 * more efficient if both clone and copy are supported (e.g. NFS).
 	 */
 	if (file_in->f_op->remap_file_range) {
-		ret = file_in->f_op->remap_file_range(file_in, pos_in,
-				file_out, pos_out, len, 0);
-		if (ret == 0) {
-			ret = len;
+		loff_t cloned;
+
+		cloned = file_in->f_op->remap_file_range(file_in, pos_in,
+				file_out, pos_out,
+				min_t(loff_t, MAX_RW_COUNT, len), 0);
+		if (cloned > 0) {
+			ret = cloned;
 			goto done;
 		}
 	}
@@ -1686,11 +1689,12 @@ SYSCALL_DEFINE6(copy_file_range, int, fd_in, loff_t
__user *, off_in,
 	return ret;
 }
 
-static int remap_verify_area(struct file *file, loff_t pos, u64 len, bool
write)
+static int remap_verify_area(struct file *file, loff_t pos, loff_t len,
+			     bool write)
 {
 	struct inode *inode = file_inode(file);
 
-	if (unlikely(pos < 0))
+	if (unlikely(pos < 0 || len < 0))
 		return -EINVAL;
 
 	 if (unlikely((loff_t) (pos + len) < 0))
@@ -1721,7 +1725,7 @@ static int remap_verify_area(struct file *file, loff_t
pos, u64 len, bool write)
 static int generic_remap_check_len(struct inode *inode_in,
 				   struct inode *inode_out,
 				   loff_t pos_out,
-				   u64 *len,
+				   loff_t *len,
 				   unsigned int remap_flags)
 {
 	u64 blkmask = i_blocksize(inode_in) - 1;
@@ -1771,7 +1775,7 @@ static int generic_remap_file_range_target(struct file
*file,
  */
 int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
 				  struct file *file_out, loff_t pos_out,
-				  u64 *len, unsigned int remap_flags)
+				  loff_t *len, unsigned int remap_flags)
 {
 	struct inode *inode_in = file_inode(file_in);
 	struct inode *inode_out = file_inode(file_out);
@@ -1852,12 +1856,12 @@ int generic_remap_file_range_prep(struct file *file_in,
loff_t pos_in,
 }
 EXPORT_SYMBOL(generic_remap_file_range_prep);
 
-int do_clone_file_range(struct file *file_in, loff_t pos_in,
-			struct file *file_out, loff_t pos_out, u64 len)
+loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
+			   struct file *file_out, loff_t pos_out, loff_t len)
 {
 	struct inode *inode_in = file_inode(file_in);
 	struct inode *inode_out = file_inode(file_out);
-	int ret;
+	loff_t ret;
 
 	if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
 		return -EISDIR;
@@ -1890,19 +1894,19 @@ int do_clone_file_range(struct file *file_in, loff_t
pos_in,
 
 	ret = file_in->f_op->remap_file_range(file_in, pos_in,
 			file_out, pos_out, len, 0);
-	if (!ret) {
-		fsnotify_access(file_in);
-		fsnotify_modify(file_out);
-	}
+	if (ret < 0)
+		return ret;
 
+	fsnotify_access(file_in);
+	fsnotify_modify(file_out);
 	return ret;
 }
 EXPORT_SYMBOL(do_clone_file_range);
 
-int vfs_clone_file_range(struct file *file_in, loff_t pos_in,
-			 struct file *file_out, loff_t pos_out, u64 len)
+loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in,
+			    struct file *file_out, loff_t pos_out, loff_t len)
 {
-	int ret;
+	loff_t ret;
 
 	file_start_write(file_out);
 	ret = do_clone_file_range(file_in, pos_in, file_out, pos_out, len);
@@ -2008,10 +2012,11 @@ int vfs_dedupe_file_range_compare(struct inode *src,
loff_t srcoff,
 }
 EXPORT_SYMBOL(vfs_dedupe_file_range_compare);
 
-int vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
-			      struct file *dst_file, loff_t dst_pos, u64 len)
+loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
+				 struct file *dst_file, loff_t dst_pos,
+				 loff_t len)
 {
-	s64 ret;
+	loff_t ret;
 
 	ret = mnt_want_write_file(dst_file);
 	if (ret)
@@ -2060,7 +2065,7 @@ int vfs_dedupe_file_range(struct file *file, struct
file_dedupe_range *same)
 	int i;
 	int ret;
 	u16 count = same->dest_count;
-	int deduped;
+	loff_t deduped;
 
 	if (!(file->f_mode & FMODE_READ))
 		return -EINVAL;
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 20314eb4677a..38fde4e11714 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -919,20 +919,23 @@ xfs_file_fallocate(
 	return error;
 }
 
-STATIC int
+STATIC loff_t
 xfs_file_remap_range(
 	struct file	*file_in,
 	loff_t		pos_in,
 	struct file	*file_out,
 	loff_t		pos_out,
-	u64		len,
+	loff_t		len,
 	unsigned int	remap_flags)
 {
+	int		ret;
+
 	if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY))
 		return -EINVAL;
 
-	return xfs_reflink_remap_range(file_in, pos_in, file_out, pos_out,
+	ret = xfs_reflink_remap_range(file_in, pos_in, file_out, pos_out,
 			len, remap_flags);
+	return ret < 0 ? ret : len;
 }
 
 STATIC int
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 2d7dd8b28d7c..3dbe5fb7e9c0 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -1296,7 +1296,7 @@ xfs_reflink_remap_prep(
 	loff_t			pos_in,
 	struct file		*file_out,
 	loff_t			pos_out,
-	u64			*len,
+	loff_t			*len,
 	unsigned int		remap_flags)
 {
 	struct inode		*inode_in = file_inode(file_in);
@@ -1387,7 +1387,7 @@ xfs_reflink_remap_range(
 	loff_t			pos_in,
 	struct file		*file_out,
 	loff_t			pos_out,
-	u64			len,
+	loff_t			len,
 	unsigned int		remap_flags)
 {
 	struct inode		*inode_in = file_inode(file_in);
diff --git a/fs/xfs/xfs_reflink.h b/fs/xfs/xfs_reflink.h
index 6f82d628bf17..c3c46c276fe1 100644
--- a/fs/xfs/xfs_reflink.h
+++ b/fs/xfs/xfs_reflink.h
@@ -28,7 +28,7 @@ extern int xfs_reflink_end_cow(struct xfs_inode *ip, xfs_off_t
offset,
 		xfs_off_t count);
 extern int xfs_reflink_recover_cow(struct xfs_mount *mp);
 extern int xfs_reflink_remap_range(struct file *file_in, loff_t pos_in,
-		struct file *file_out, loff_t pos_out, u64 len,
+		struct file *file_out, loff_t pos_out, loff_t len,
 		unsigned int remap_flags);
 extern int xfs_reflink_inode_has_shared_extents(struct xfs_trans *tp,
 		struct xfs_inode *ip, bool *has_shared);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 1aa3bc1bb092..f1d082af34d0 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1772,9 +1772,9 @@ struct file_operations {
 #endif
 	ssize_t (*copy_file_range)(struct file *, loff_t, struct file *,
 			loff_t, size_t, unsigned int);
-	int (*remap_file_range)(struct file *file_in, loff_t pos_in,
-				struct file *file_out, loff_t pos_out,
-				u64 len, unsigned int remap_flags);
+	loff_t (*remap_file_range)(struct file *file_in, loff_t pos_in,
+				   struct file *file_out, loff_t pos_out,
+				   loff_t len, unsigned int remap_flags);
 	int (*fadvise)(struct file *, loff_t, loff_t, int);
 } __randomize_layout;
 
@@ -1839,19 +1839,22 @@ extern ssize_t vfs_copy_file_range(struct file *, loff_t
, struct file *,
 				   loff_t, size_t, unsigned int);
 extern int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
 					 struct file *file_out, loff_t pos_out,
-					 u64 *count, unsigned int remap_flags);
-extern int do_clone_file_range(struct file *file_in, loff_t pos_in,
-			       struct file *file_out, loff_t pos_out, u64 len);
-extern int vfs_clone_file_range(struct file *file_in, loff_t pos_in,
-				struct file *file_out, loff_t pos_out, u64 len);
+					 loff_t *count,
+					 unsigned int remap_flags);
+extern loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
+				  struct file *file_out, loff_t pos_out,
+				  loff_t len);
+extern loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in,
+				   struct file *file_out, loff_t pos_out,
+				   loff_t len);
 extern int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
 					 struct inode *dest, loff_t destoff,
 					 loff_t len, bool *is_same);
 extern int vfs_dedupe_file_range(struct file *file,
 				 struct file_dedupe_range *same);
-extern int vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
-				     struct file *dst_file, loff_t dst_pos,
-				     u64 len);
+extern loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
+					struct file *dst_file, loff_t dst_pos,
+					loff_t len);
 
 
 struct super_operations {
@@ -2981,7 +2984,7 @@ extern int generic_file_readonly_mmap(struct file *,
struct vm_area_struct *);
 extern ssize_t generic_write_checks(struct kiocb *, struct iov_iter *);
 extern int generic_remap_checks(struct file *file_in, loff_t pos_in,
 				struct file *file_out, loff_t pos_out,
-				uint64_t *count, unsigned int remap_flags);
+				loff_t *count, unsigned int remap_flags);
 extern ssize_t generic_file_read_iter(struct kiocb *, struct iov_iter *);
 extern ssize_t __generic_file_write_iter(struct kiocb *, struct iov_iter *);
 extern ssize_t generic_file_write_iter(struct kiocb *, struct iov_iter *);
diff --git a/mm/filemap.c b/mm/filemap.c
index b0f1f6d93d9c..1e93269efafe 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3001,7 +3001,7 @@ EXPORT_SYMBOL(generic_write_checks);
  */
 int generic_remap_checks(struct file *file_in, loff_t pos_in,
 			 struct file *file_out, loff_t pos_out,
-			 uint64_t *req_count, unsigned int remap_flags)
+			 loff_t *req_count, unsigned int remap_flags)
 {
 	struct inode *inode_in = file_in->f_mapping->host;
 	struct inode *inode_out = file_out->f_mapping->host;

From: Darrick J. Wong <darrick.wong at oracle.com>

Plumb a remap_flags argument through the {do,vfs}_clone_file_range
functions so that clone can take advantage of it.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
Reviewed-by: Amir Goldstein <amir73il at gmail.com>
---
 fs/ioctl.c             |    2 +-
 fs/nfsd/vfs.c          |    2 +-
 fs/overlayfs/copy_up.c |    2 +-
 fs/overlayfs/file.c    |    6 +++---
 fs/read_write.c        |   13 +++++++++----
 include/linux/fs.h     |    4 ++--
 6 files changed, 17 insertions(+), 12 deletions(-)


diff --git a/fs/ioctl.c b/fs/ioctl.c
index 72537b68c272..505275ec5596 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -232,7 +232,7 @@ static long ioctl_file_clone(struct file *dst_file, unsigned
long srcfd,
 	if (src_file.file->f_path.mnt != dst_file->f_path.mnt)
 		goto fdput;
 	cloned = vfs_clone_file_range(src_file.file, off, dst_file, destoff,
-				      olen);
+				      olen, 0);
 	if (cloned < 0)
 		ret = cloned;
 	else if (olen && cloned != olen)
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index ac6cb6101cbe..726fc5b2b27a 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -543,7 +543,7 @@ __be32 nfsd4_clone_file_range(struct file *src, u64 src_pos,
struct file *dst,
 {
 	loff_t cloned;
 
-	cloned = vfs_clone_file_range(src, src_pos, dst, dst_pos, count);
+	cloned = vfs_clone_file_range(src, src_pos, dst, dst_pos, count, 0);
 	if (count && cloned != count)
 		cloned = -EINVAL;
 	return nfserrno(cloned < 0 ? cloned : 0);
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index 8750b7235516..5f82fece64a0 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -142,7 +142,7 @@ static int ovl_copy_up_data(struct path *old, struct path
*new, loff_t len)
 	}
 
 	/* Try to use clone_file_range to clone up within the same fs */
-	cloned = do_clone_file_range(old_file, 0, new_file, 0, len);
+	cloned = do_clone_file_range(old_file, 0, new_file, 0, len, 0);
 	if (cloned == len)
 		goto out;
 	/* Couldn't clone, so now we try to copy the data */
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index 6c3fec6168e9..0393815c8971 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -462,7 +462,7 @@ static loff_t ovl_copyfile(struct file *file_in, loff_t
pos_in,
 
 	case OVL_CLONE:
 		ret = vfs_clone_file_range(real_in.file, pos_in,
-					   real_out.file, pos_out, len);
+					   real_out.file, pos_out, len, flags);
 		break;
 
 	case OVL_DEDUPE:
@@ -512,8 +512,8 @@ static loff_t ovl_remap_file_range(struct file *file_in,
loff_t pos_in,
 	     !ovl_inode_upper(file_inode(file_out))))
 		return -EPERM;
 
-	return ovl_copyfile(file_in, pos_in, file_out, pos_out, len, 0,
-			    op);
+	return ovl_copyfile(file_in, pos_in, file_out, pos_out, len,
+			    remap_flags, op);
 }
 
 const struct file_operations ovl_file_operations = {
diff --git a/fs/read_write.c b/fs/read_write.c
index 906e78be5001..791b406e8264 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1857,12 +1857,15 @@ int generic_remap_file_range_prep(struct file *file_in,
loff_t pos_in,
 EXPORT_SYMBOL(generic_remap_file_range_prep);
 
 loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
-			   struct file *file_out, loff_t pos_out, loff_t len)
+			   struct file *file_out, loff_t pos_out,
+			   loff_t len, unsigned int remap_flags)
 {
 	struct inode *inode_in = file_inode(file_in);
 	struct inode *inode_out = file_inode(file_out);
 	loff_t ret;
 
+	WARN_ON_ONCE(remap_flags);
+
 	if (S_ISDIR(inode_in->i_mode) || S_ISDIR(inode_out->i_mode))
 		return -EISDIR;
 	if (!S_ISREG(inode_in->i_mode) || !S_ISREG(inode_out->i_mode))
@@ -1893,7 +1896,7 @@ loff_t do_clone_file_range(struct file *file_in, loff_t
pos_in,
 		return ret;
 
 	ret = file_in->f_op->remap_file_range(file_in, pos_in,
-			file_out, pos_out, len, 0);
+			file_out, pos_out, len, remap_flags);
 	if (ret < 0)
 		return ret;
 
@@ -1904,12 +1907,14 @@ loff_t do_clone_file_range(struct file *file_in, loff_t
pos_in,
 EXPORT_SYMBOL(do_clone_file_range);
 
 loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in,
-			    struct file *file_out, loff_t pos_out, loff_t len)
+			    struct file *file_out, loff_t pos_out,
+			    loff_t len, unsigned int remap_flags)
 {
 	loff_t ret;
 
 	file_start_write(file_out);
-	ret = do_clone_file_range(file_in, pos_in, file_out, pos_out, len);
+	ret = do_clone_file_range(file_in, pos_in, file_out, pos_out, len,
+				  remap_flags);
 	file_end_write(file_out);
 
 	return ret;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index f1d082af34d0..bc353a5224a4 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1843,10 +1843,10 @@ extern int generic_remap_file_range_prep(struct file
*file_in, loff_t pos_in,
 					 unsigned int remap_flags);
 extern loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
 				  struct file *file_out, loff_t pos_out,
-				  loff_t len);
+				  loff_t len, unsigned int remap_flags);
 extern loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in,
 				   struct file *file_out, loff_t pos_out,
-				   loff_t len);
+				   loff_t len, unsigned int remap_flags);
 extern int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
 					 struct inode *dest, loff_t destoff,
 					 loff_t len, bool *is_same);

From: Darrick J. Wong <darrick.wong at oracle.com>

Plumb a remap_flags argument through the vfs_dedupe_file_range_one
functions so that dedupe can take advantage of it.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
Reviewed-by: Amir Goldstein <amir73il at gmail.com>
---
 fs/overlayfs/file.c |    3 ++-
 fs/read_write.c     |    9 ++++++---
 include/linux/fs.h  |    2 +-
 3 files changed, 9 insertions(+), 5 deletions(-)


diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index 0393815c8971..84dd957efa24 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -467,7 +467,8 @@ static loff_t ovl_copyfile(struct file *file_in, loff_t
pos_in,
 
 	case OVL_DEDUPE:
 		ret = vfs_dedupe_file_range_one(real_in.file, pos_in,
-						real_out.file, pos_out, len);
+						real_out.file, pos_out, len,
+						flags);
 		break;
 	}
 	revert_creds(old_cred);
diff --git a/fs/read_write.c b/fs/read_write.c
index 791b406e8264..f6ab5beb935a 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -2019,10 +2019,12 @@ EXPORT_SYMBOL(vfs_dedupe_file_range_compare);
 
 loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
 				 struct file *dst_file, loff_t dst_pos,
-				 loff_t len)
+				 loff_t len, unsigned int remap_flags)
 {
 	loff_t ret;
 
+	WARN_ON_ONCE(remap_flags & ~(REMAP_FILE_DEDUP));
+
 	ret = mnt_want_write_file(dst_file);
 	if (ret)
 		return ret;
@@ -2053,7 +2055,7 @@ loff_t vfs_dedupe_file_range_one(struct file *src_file,
loff_t src_pos,
 	}
 
 	ret = dst_file->f_op->remap_file_range(src_file, src_pos, dst_file,
-			dst_pos, len, REMAP_FILE_DEDUP);
+			dst_pos, len, remap_flags | REMAP_FILE_DEDUP);
 out_drop_write:
 	mnt_drop_write_file(dst_file);
 
@@ -2121,7 +2123,8 @@ int vfs_dedupe_file_range(struct file *file, struct
file_dedupe_range *same)
 		}
 
 		deduped = vfs_dedupe_file_range_one(file, off, dst_file,
-						    info->dest_offset, len);
+						    info->dest_offset, len,
+						    0);
 		if (deduped == -EBADE)
 			info->status = FILE_DEDUPE_RANGE_DIFFERS;
 		else if (deduped < 0)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index bc353a5224a4..c0ae85a7bd9d 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1854,7 +1854,7 @@ extern int vfs_dedupe_file_range(struct file *file,
 				 struct file_dedupe_range *same);
 extern loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
 					struct file *dst_file, loff_t dst_pos,
-					loff_t len);
+					loff_t len, unsigned int remap_flags);
 
 
 struct super_operations {

From: Darrick J. Wong <darrick.wong at oracle.com>

Plumb in a remap flag that enables the filesystem remap handler to
shorten remapping requests for callers that can handle it.  Now
copy_file_range can report partial success (in case we run up against
alignment problems, resource limits, etc.).

We also enable CAN_SHORTEN for fideduperange to maintain existing
userspace-visible behavior where xfs/btrfs shorten the dedupe range to
avoid stale post-eof data exposure.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
Reviewed-by: Amir Goldstein <amir73il at gmail.com>
---
 fs/read_write.c    |   28 ++++++++++++++++++++--------
 include/linux/fs.h |    7 +++++--
 mm/filemap.c       |   16 ++++++++++++----
 3 files changed, 37 insertions(+), 14 deletions(-)


diff --git a/fs/read_write.c b/fs/read_write.c
index f6ab5beb935a..ee9314b7bfc3 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1593,7 +1593,8 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t
pos_in,
 
 		cloned = file_in->f_op->remap_file_range(file_in, pos_in,
 				file_out, pos_out,
-				min_t(loff_t, MAX_RW_COUNT, len), 0);
+				min_t(loff_t, MAX_RW_COUNT, len),
+				REMAP_FILE_CAN_SHORTEN);
 		if (cloned > 0) {
 			ret = cloned;
 			goto done;
@@ -1721,6 +1722,8 @@ static int remap_verify_area(struct file *file, loff_t
pos, loff_t len,
  * can't meaningfully compare post-EOF contents.
  *
  * For clone we only link a partial EOF block above the destination file's
EOF.
+ *
+ * Shorten the request if possible.
  */
 static int generic_remap_check_len(struct inode *inode_in,
 				   struct inode *inode_out,
@@ -1729,16 +1732,24 @@ static int generic_remap_check_len(struct inode
*inode_in,
 				   unsigned int remap_flags)
 {
 	u64 blkmask = i_blocksize(inode_in) - 1;
+	loff_t new_len = *len;
 
 	if ((*len & blkmask) == 0)
 		return 0;
 
-	if (remap_flags & REMAP_FILE_DEDUP)
-		*len &= ~blkmask;
-	else if (pos_out + *len < i_size_read(inode_out))
-		return -EINVAL;
+	if ((remap_flags & REMAP_FILE_DEDUP) ||
+	    pos_out + *len < i_size_read(inode_out))
+		new_len &= ~blkmask;
 
-	return 0;
+	if (new_len == *len)
+		return 0;
+
+	if (remap_flags & REMAP_FILE_CAN_SHORTEN) {
+		*len = new_len;
+		return 0;
+	}
+
+	return (remap_flags & REMAP_FILE_DEDUP) ? -EBADE : -EINVAL;
 }
 
 /* Update inode timestamps and remove security privileges when remapping. */
@@ -2023,7 +2034,8 @@ loff_t vfs_dedupe_file_range_one(struct file *src_file,
loff_t src_pos,
 {
 	loff_t ret;
 
-	WARN_ON_ONCE(remap_flags & ~(REMAP_FILE_DEDUP));
+	WARN_ON_ONCE(remap_flags & ~(REMAP_FILE_DEDUP |
+				     REMAP_FILE_CAN_SHORTEN));
 
 	ret = mnt_want_write_file(dst_file);
 	if (ret)
@@ -2124,7 +2136,7 @@ int vfs_dedupe_file_range(struct file *file, struct
file_dedupe_range *same)
 
 		deduped = vfs_dedupe_file_range_one(file, off, dst_file,
 						    info->dest_offset, len,
-						    0);
+						    REMAP_FILE_CAN_SHORTEN);
 		if (deduped == -EBADE)
 			info->status = FILE_DEDUPE_RANGE_DIFFERS;
 		else if (deduped < 0)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index c0ae85a7bd9d..594fe4ba0b15 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1726,14 +1726,17 @@ struct block_device_operations;
  * If it is called with len == 0 that means "remap to end of source
file".
  *
  * REMAP_FILE_DEDUP: only remap if contents identical (i.e. deduplicate)
+ * REMAP_FILE_CAN_SHORTEN: caller can handle a shortened request
  */
 #define REMAP_FILE_DEDUP		(1 << 0)
+#define REMAP_FILE_CAN_SHORTEN		(1 << 1)
 
 /* All valid REMAP_FILE flags */
-#define REMAP_FILE_VALID_FLAGS		(REMAP_FILE_DEDUP)
+#define REMAP_FILE_VALID_FLAGS		(REMAP_FILE_DEDUP | \
+					 REMAP_FILE_CAN_SHORTEN)
 
 /* REMAP_FILE flags taken care of by the vfs. */
-#define REMAP_FILE_ADVISORY		(0)
+#define REMAP_FILE_ADVISORY		(REMAP_FILE_CAN_SHORTEN)
 
 struct iov_iter;
 
diff --git a/mm/filemap.c b/mm/filemap.c
index 1e93269efafe..898eb358f7d2 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3051,8 +3051,12 @@ int generic_remap_checks(struct file *file_in, loff_t
pos_in,
 	if (pos_in + count == size_in) {
 		bcount = ALIGN(size_in, bs) - pos_in;
 	} else {
-		if (!IS_ALIGNED(count, bs))
-			return -EINVAL;
+		if (!IS_ALIGNED(count, bs)) {
+			if (remap_flags & REMAP_FILE_CAN_SHORTEN)
+				count = ALIGN_DOWN(count, bs);
+			else
+				return -EINVAL;
+		}
 
 		bcount = count;
 	}
@@ -3063,10 +3067,14 @@ int generic_remap_checks(struct file *file_in, loff_t
pos_in,
 	    pos_out < pos_in + bcount)
 		return -EINVAL;
 
-	/* For now we don't support changing the length. */
-	if (*req_count != count)
+	/*
+	 * We shortened the request but the caller can't deal with that, so
+	 * bounce the request back to userspace.
+	 */
+	if (*req_count != count && !(remap_flags &
REMAP_FILE_CAN_SHORTEN))
 		return -EINVAL;
 
+	*req_count = count;
 	return 0;
 }

From: Darrick J. Wong <darrick.wong at oracle.com>

There are no callers of vfs_dedupe_file_range_compare, so we might as
well make it a static helper and remove the export.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
Reviewed-by: Amir Goldstein <amir73il at gmail.com>
Reviewed-by: Christoph Hellwig <hch at lst.de>
---
 fs/read_write.c    |  187 +++++++++++++++++++++++++---------------------------
 include/linux/fs.h |    3 -
 2 files changed, 91 insertions(+), 99 deletions(-)


diff --git a/fs/read_write.c b/fs/read_write.c
index ee9314b7bfc3..450e038e8617 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1776,6 +1776,97 @@ static int generic_remap_file_range_target(struct file
*file,
 	return file_remove_privs(file);
 }
 
+/*
+ * Read a page's worth of file data into the page cache.  Return the page
+ * locked.
+ */
+static struct page *vfs_dedupe_get_page(struct inode *inode, loff_t offset)
+{
+	struct page *page;
+
+	page = read_mapping_page(inode->i_mapping, offset >> PAGE_SHIFT,
NULL);
+	if (IS_ERR(page))
+		return page;
+	if (!PageUptodate(page)) {
+		put_page(page);
+		return ERR_PTR(-EIO);
+	}
+	lock_page(page);
+	return page;
+}
+
+/*
+ * Compare extents of two files to see if they are the same.
+ * Caller must have locked both inodes to prevent write races.
+ */
+static int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
+					 struct inode *dest, loff_t destoff,
+					 loff_t len, bool *is_same)
+{
+	loff_t src_poff;
+	loff_t dest_poff;
+	void *src_addr;
+	void *dest_addr;
+	struct page *src_page;
+	struct page *dest_page;
+	loff_t cmp_len;
+	bool same;
+	int error;
+
+	error = -EINVAL;
+	same = true;
+	while (len) {
+		src_poff = srcoff & (PAGE_SIZE - 1);
+		dest_poff = destoff & (PAGE_SIZE - 1);
+		cmp_len = min(PAGE_SIZE - src_poff,
+			      PAGE_SIZE - dest_poff);
+		cmp_len = min(cmp_len, len);
+		if (cmp_len <= 0)
+			goto out_error;
+
+		src_page = vfs_dedupe_get_page(src, srcoff);
+		if (IS_ERR(src_page)) {
+			error = PTR_ERR(src_page);
+			goto out_error;
+		}
+		dest_page = vfs_dedupe_get_page(dest, destoff);
+		if (IS_ERR(dest_page)) {
+			error = PTR_ERR(dest_page);
+			unlock_page(src_page);
+			put_page(src_page);
+			goto out_error;
+		}
+		src_addr = kmap_atomic(src_page);
+		dest_addr = kmap_atomic(dest_page);
+
+		flush_dcache_page(src_page);
+		flush_dcache_page(dest_page);
+
+		if (memcmp(src_addr + src_poff, dest_addr + dest_poff, cmp_len))
+			same = false;
+
+		kunmap_atomic(dest_addr);
+		kunmap_atomic(src_addr);
+		unlock_page(dest_page);
+		unlock_page(src_page);
+		put_page(dest_page);
+		put_page(src_page);
+
+		if (!same)
+			break;
+
+		srcoff += cmp_len;
+		destoff += cmp_len;
+		len -= cmp_len;
+	}
+
+	*is_same = same;
+	return 0;
+
+out_error:
+	return error;
+}
+
 /*
  * Check that the two inodes are eligible for cloning, the ranges make
  * sense, and then flush all dirty data.  Caller must ensure that the
@@ -1932,102 +2023,6 @@ loff_t vfs_clone_file_range(struct file *file_in, loff_t
pos_in,
 }
 EXPORT_SYMBOL(vfs_clone_file_range);
 
-/*
- * Read a page's worth of file data into the page cache.  Return the page
- * locked.
- */
-static struct page *vfs_dedupe_get_page(struct inode *inode, loff_t offset)
-{
-	struct address_space *mapping;
-	struct page *page;
-	pgoff_t n;
-
-	n = offset >> PAGE_SHIFT;
-	mapping = inode->i_mapping;
-	page = read_mapping_page(mapping, n, NULL);
-	if (IS_ERR(page))
-		return page;
-	if (!PageUptodate(page)) {
-		put_page(page);
-		return ERR_PTR(-EIO);
-	}
-	lock_page(page);
-	return page;
-}
-
-/*
- * Compare extents of two files to see if they are the same.
- * Caller must have locked both inodes to prevent write races.
- */
-int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
-				  struct inode *dest, loff_t destoff,
-				  loff_t len, bool *is_same)
-{
-	loff_t src_poff;
-	loff_t dest_poff;
-	void *src_addr;
-	void *dest_addr;
-	struct page *src_page;
-	struct page *dest_page;
-	loff_t cmp_len;
-	bool same;
-	int error;
-
-	error = -EINVAL;
-	same = true;
-	while (len) {
-		src_poff = srcoff & (PAGE_SIZE - 1);
-		dest_poff = destoff & (PAGE_SIZE - 1);
-		cmp_len = min(PAGE_SIZE - src_poff,
-			      PAGE_SIZE - dest_poff);
-		cmp_len = min(cmp_len, len);
-		if (cmp_len <= 0)
-			goto out_error;
-
-		src_page = vfs_dedupe_get_page(src, srcoff);
-		if (IS_ERR(src_page)) {
-			error = PTR_ERR(src_page);
-			goto out_error;
-		}
-		dest_page = vfs_dedupe_get_page(dest, destoff);
-		if (IS_ERR(dest_page)) {
-			error = PTR_ERR(dest_page);
-			unlock_page(src_page);
-			put_page(src_page);
-			goto out_error;
-		}
-		src_addr = kmap_atomic(src_page);
-		dest_addr = kmap_atomic(dest_page);
-
-		flush_dcache_page(src_page);
-		flush_dcache_page(dest_page);
-
-		if (memcmp(src_addr + src_poff, dest_addr + dest_poff, cmp_len))
-			same = false;
-
-		kunmap_atomic(dest_addr);
-		kunmap_atomic(src_addr);
-		unlock_page(dest_page);
-		unlock_page(src_page);
-		put_page(dest_page);
-		put_page(src_page);
-
-		if (!same)
-			break;
-
-		srcoff += cmp_len;
-		destoff += cmp_len;
-		len -= cmp_len;
-	}
-
-	*is_same = same;
-	return 0;
-
-out_error:
-	return error;
-}
-EXPORT_SYMBOL(vfs_dedupe_file_range_compare);
-
 loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
 				 struct file *dst_file, loff_t dst_pos,
 				 loff_t len, unsigned int remap_flags)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 594fe4ba0b15..92eec706172f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1850,9 +1850,6 @@ extern loff_t do_clone_file_range(struct file *file_in,
loff_t pos_in,
 extern loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in,
 				   struct file *file_out, loff_t pos_out,
 				   loff_t len, unsigned int remap_flags);
-extern int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
-					 struct inode *dest, loff_t destoff,
-					 loff_t len, bool *is_same);
 extern int vfs_dedupe_file_range(struct file *file,
 				 struct file_dedupe_range *same);
 extern loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,

From: Darrick J. Wong <darrick.wong at oracle.com>

Since the remap prep function can update the length of the remap
request, we can change this function to return the usual return status
instead of the odd behavior it has now.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
---
 fs/ocfs2/refcounttree.c |    2 +-
 fs/read_write.c         |    6 +++---
 fs/xfs/xfs_reflink.c    |    4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)


diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index 6a42c04ac0ab..46bbd315c39f 100644
--- a/fs/ocfs2/refcounttree.c
+++ b/fs/ocfs2/refcounttree.c
@@ -4852,7 +4852,7 @@ int ocfs2_reflink_remap_range(struct file *file_in,
 
 	ret = generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out,
 			&len, remap_flags);
-	if (ret <= 0)
+	if (ret < 0 || len == 0)
 		goto out_unlock;
 
 	/* Lock out changes to the allocation maps and remap. */
diff --git a/fs/read_write.c b/fs/read_write.c
index 450e038e8617..37a7d3fe35d8 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1872,8 +1872,8 @@ static int vfs_dedupe_file_range_compare(struct inode
*src, loff_t srcoff,
  * sense, and then flush all dirty data.  Caller must ensure that the
  * inodes have been locked against any other modifications.
  *
- * Returns: 0 for "nothing to clone", 1 for "something to
clone", or
- * the usual negative error code.
+ * If there's an error, then the usual negative error code is returned.
+ * Otherwise returns 0 with *len set to the request length.
  */
 int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
 				  struct file *file_out, loff_t pos_out,
@@ -1954,7 +1954,7 @@ int generic_remap_file_range_prep(struct file *file_in,
loff_t pos_in,
 	if (ret)
 		return ret;
 
-	return 1;
+	return 0;
 }
 EXPORT_SYMBOL(generic_remap_file_range_prep);
 
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 3dbe5fb7e9c0..9b1ea42c81d1 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -1329,7 +1329,7 @@ xfs_reflink_remap_prep(
 
 	ret = generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out,
 			len, remap_flags);
-	if (ret <= 0)
+	if (ret < 0 || *len == 0)
 		goto out_unlock;
 
 	/*
@@ -1409,7 +1409,7 @@ xfs_reflink_remap_range(
 	/* Prepare and then clone file data. */
 	ret = xfs_reflink_remap_prep(file_in, pos_in, file_out, pos_out,
 			&len, remap_flags);
-	if (ret <= 0)
+	if (ret < 0 || len == 0)
 		return ret;
 
 	trace_xfs_reflink_remap_range(src, pos_in, len, dest, pos_out);

From: Darrick J. Wong <darrick.wong at oracle.com>

When cloning blocks into another file, truncate the page cache before we
start remapping blocks so that concurrent reads wait for us to finish.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
---
 fs/ocfs2/refcounttree.c |   10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)


diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index 46bbd315c39f..2a5c96bc9677 100644
--- a/fs/ocfs2/refcounttree.c
+++ b/fs/ocfs2/refcounttree.c
@@ -4861,14 +4861,12 @@ int ocfs2_reflink_remap_range(struct file *file_in,
 		down_write_nested(&OCFS2_I(inode_out)->ip_alloc_sem,
 				  SINGLE_DEPTH_NESTING);
 
-	ret = ocfs2_reflink_remap_blocks(inode_in, in_bh, pos_in, inode_out,
-					 out_bh, pos_out, len);
-
 	/* Zap any page cache for the destination file's range. */
-	if (!ret)
-		truncate_inode_pages_range(&inode_out->i_data, pos_out,
-					   PAGE_ALIGN(pos_out + len) - 1);
+	truncate_inode_pages_range(&inode_out->i_data, pos_out,
+				   PAGE_ALIGN(pos_out + len) - 1);
 
+	ret = ocfs2_reflink_remap_blocks(inode_in, in_bh, pos_in, inode_out,
+					 out_bh, pos_out, len);
 	up_write(&OCFS2_I(inode_in)->ip_alloc_sem);
 	if (!same_inode)
 		up_write(&OCFS2_I(inode_out)->ip_alloc_sem);

From: Darrick J. Wong <darrick.wong at oracle.com>

Prior to remapping blocks, it is necessary to remove pages from the
destination file's page cache.  Unfortunately, the truncation is not
aggressive enough -- if page size > block size, we'll end up zeroing
subpage blocks instead of removing them.  So, round the start offset
down and the end offset up to page boundaries.  We already wrote all
the dirty data so the larger range should be fine.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
---
 fs/ocfs2/refcounttree.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)


diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index 2a5c96bc9677..7c709229e108 100644
--- a/fs/ocfs2/refcounttree.c
+++ b/fs/ocfs2/refcounttree.c
@@ -4862,8 +4862,9 @@ int ocfs2_reflink_remap_range(struct file *file_in,
 				  SINGLE_DEPTH_NESTING);
 
 	/* Zap any page cache for the destination file's range. */
-	truncate_inode_pages_range(&inode_out->i_data, pos_out,
-				   PAGE_ALIGN(pos_out + len) - 1);
+	truncate_inode_pages_range(&inode_out->i_data,
+				   round_down(pos_out, PAGE_SIZE),
+				   round_up(pos_out + len, PAGE_SIZE) - 1);
 
 	ret = ocfs2_reflink_remap_blocks(inode_in, in_bh, pos_in, inode_out,
 					 out_bh, pos_out, len);

From: Darrick J. Wong <darrick.wong at oracle.com>

Change the ocfs2 remap code to allow for returning partial results.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
---
 fs/ocfs2/file.c         |    7 +----
 fs/ocfs2/refcounttree.c |   72 +++++++++++++++++++++++++----------------------
 fs/ocfs2/refcounttree.h |   12 ++++----
 3 files changed, 46 insertions(+), 45 deletions(-)


diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index fbaeafe44b5f..8125c5ccf821 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2531,14 +2531,11 @@ static loff_t ocfs2_remap_file_range(struct file
*file_in, loff_t pos_in,
 				     struct file *file_out, loff_t pos_out,
 				     loff_t len, unsigned int remap_flags)
 {
-	int ret;
-
 	if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY))
 		return -EINVAL;
 
-	ret = ocfs2_reflink_remap_range(file_in, pos_in, file_out, pos_out,
-					len, remap_flags);
-	return ret < 0 ? ret : len;
+	return ocfs2_reflink_remap_range(file_in, pos_in, file_out, pos_out,
+			len, remap_flags);
 }
 
 const struct inode_operations ocfs2_file_iops = {
diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index 7c709229e108..c7409578657b 100644
--- a/fs/ocfs2/refcounttree.c
+++ b/fs/ocfs2/refcounttree.c
@@ -4507,14 +4507,14 @@ static int ocfs2_reflink_update_dest(struct inode *dest,
 }
 
 /* Remap the range pos_in:len in s_inode to pos_out:len in t_inode. */
-static int ocfs2_reflink_remap_extent(struct inode *s_inode,
-				      struct buffer_head *s_bh,
-				      loff_t pos_in,
-				      struct inode *t_inode,
-				      struct buffer_head *t_bh,
-				      loff_t pos_out,
-				      loff_t len,
-				      struct ocfs2_cached_dealloc_ctxt *dealloc)
+static loff_t ocfs2_reflink_remap_extent(struct inode *s_inode,
+					 struct buffer_head *s_bh,
+					 loff_t pos_in,
+					 struct inode *t_inode,
+					 struct buffer_head *t_bh,
+					 loff_t pos_out,
+					 loff_t len,
+					 struct ocfs2_cached_dealloc_ctxt *dealloc)
 {
 	struct ocfs2_extent_tree s_et;
 	struct ocfs2_extent_tree t_et;
@@ -4522,8 +4522,9 @@ static int ocfs2_reflink_remap_extent(struct inode
*s_inode,
 	struct buffer_head *ref_root_bh = NULL;
 	struct ocfs2_refcount_tree *ref_tree;
 	struct ocfs2_super *osb;
+	loff_t remapped_bytes = 0;
 	loff_t pstart, plen;
-	u32 p_cluster, num_clusters, slast, spos, tpos;
+	u32 p_cluster, num_clusters, slast, spos, tpos, remapped_clus = 0;
 	unsigned int ext_flags;
 	int ret = 0;
 
@@ -4605,30 +4606,34 @@ static int ocfs2_reflink_remap_extent(struct inode
*s_inode,
 next_loop:
 		spos += num_clusters;
 		tpos += num_clusters;
+		remapped_clus += num_clusters;
 	}
 
-out:
-	return ret;
+	goto out;
 out_unlock_refcount:
 	ocfs2_unlock_refcount_tree(osb, ref_tree, 1);
 	brelse(ref_root_bh);
-	return ret;
+out:
+	remapped_bytes = ocfs2_clusters_to_bytes(t_inode->i_sb, remapped_clus);
+	remapped_bytes = min_t(loff_t, len, remapped_bytes);
+
+	return remapped_bytes > 0 ? remapped_bytes : ret;
 }
 
 /* Set up refcount tree and remap s_inode to t_inode. */
-static int ocfs2_reflink_remap_blocks(struct inode *s_inode,
-				      struct buffer_head *s_bh,
-				      loff_t pos_in,
-				      struct inode *t_inode,
-				      struct buffer_head *t_bh,
-				      loff_t pos_out,
-				      loff_t len)
+static loff_t ocfs2_reflink_remap_blocks(struct inode *s_inode,
+					 struct buffer_head *s_bh,
+					 loff_t pos_in,
+					 struct inode *t_inode,
+					 struct buffer_head *t_bh,
+					 loff_t pos_out,
+					 loff_t len)
 {
 	struct ocfs2_cached_dealloc_ctxt dealloc;
 	struct ocfs2_super *osb;
 	struct ocfs2_dinode *dis;
 	struct ocfs2_dinode *dit;
-	int ret;
+	loff_t ret;
 
 	osb = OCFS2_SB(s_inode->i_sb);
 	dis = (struct ocfs2_dinode *)s_bh->b_data;
@@ -4700,7 +4705,7 @@ static int ocfs2_reflink_remap_blocks(struct inode
*s_inode,
 	/* Actually remap extents now. */
 	ret = ocfs2_reflink_remap_extent(s_inode, s_bh, pos_in, t_inode, t_bh,
 					 pos_out, len, &dealloc);
-	if (ret) {
+	if (ret < 0) {
 		mlog_errno(ret);
 		goto out;
 	}
@@ -4820,18 +4825,19 @@ static void ocfs2_reflink_inodes_unlock(struct inode
*s_inode,
 }
 
 /* Link a range of blocks from one file to another. */
-int ocfs2_reflink_remap_range(struct file *file_in,
-			      loff_t pos_in,
-			      struct file *file_out,
-			      loff_t pos_out,
-			      loff_t len,
-			      unsigned int remap_flags)
+loff_t ocfs2_reflink_remap_range(struct file *file_in,
+				 loff_t pos_in,
+				 struct file *file_out,
+				 loff_t pos_out,
+				 loff_t len,
+				 unsigned int remap_flags)
 {
 	struct inode *inode_in = file_inode(file_in);
 	struct inode *inode_out = file_inode(file_out);
 	struct ocfs2_super *osb = OCFS2_SB(inode_in->i_sb);
 	struct buffer_head *in_bh = NULL, *out_bh = NULL;
 	bool same_inode = (inode_in == inode_out);
+	loff_t remapped = 0;
 	ssize_t ret;
 
 	if (!ocfs2_refcount_tree(osb))
@@ -4866,12 +4872,13 @@ int ocfs2_reflink_remap_range(struct file *file_in,
 				   round_down(pos_out, PAGE_SIZE),
 				   round_up(pos_out + len, PAGE_SIZE) - 1);
 
-	ret = ocfs2_reflink_remap_blocks(inode_in, in_bh, pos_in, inode_out,
-					 out_bh, pos_out, len);
+	remapped = ocfs2_reflink_remap_blocks(inode_in, in_bh, pos_in,
+			inode_out, out_bh, pos_out, len);
 	up_write(&OCFS2_I(inode_in)->ip_alloc_sem);
 	if (!same_inode)
 		up_write(&OCFS2_I(inode_out)->ip_alloc_sem);
-	if (ret) {
+	if (remapped < 0) {
+		ret = remapped;
 		mlog_errno(ret);
 		goto out_unlock;
 	}
@@ -4889,10 +4896,7 @@ int ocfs2_reflink_remap_range(struct file *file_in,
 		goto out_unlock;
 	}
 
-	ocfs2_reflink_inodes_unlock(inode_in, in_bh, inode_out, out_bh);
-	return 0;
-
 out_unlock:
 	ocfs2_reflink_inodes_unlock(inode_in, in_bh, inode_out, out_bh);
-	return ret;
+	return remapped > 0 ? remapped : ret;
 }
diff --git a/fs/ocfs2/refcounttree.h b/fs/ocfs2/refcounttree.h
index eb65c1d0843c..9e64daba395d 100644
--- a/fs/ocfs2/refcounttree.h
+++ b/fs/ocfs2/refcounttree.h
@@ -115,11 +115,11 @@ int ocfs2_reflink_ioctl(struct inode *inode,
 			const char __user *oldname,
 			const char __user *newname,
 			bool preserve);
-int ocfs2_reflink_remap_range(struct file *file_in,
-			      loff_t pos_in,
-			      struct file *file_out,
-			      loff_t pos_out,
-			      loff_t len,
-			      unsigned int remap_flags);
+loff_t ocfs2_reflink_remap_range(struct file *file_in,
+				 loff_t pos_in,
+				 struct file *file_out,
+				 loff_t pos_out,
+				 loff_t len,
+				 unsigned int remap_flags);
 
 #endif /* OCFS2_REFCOUNTTREE_H */

From: Darrick J. Wong <darrick.wong at oracle.com>

Since ocfs2_remap_file_range is a thin shell around
ocfs2_remap_remap_range, move everything from the latter into the
former.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
---
 fs/ocfs2/file.c         |   68 +++++++++++++++++++++++++++-
 fs/ocfs2/refcounttree.c |  113 +++++++----------------------------------------
 fs/ocfs2/refcounttree.h |   24 +++++++---
 3 files changed, 102 insertions(+), 103 deletions(-)


diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 8125c5ccf821..fe570824b991 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2531,11 +2531,75 @@ static loff_t ocfs2_remap_file_range(struct file
*file_in, loff_t pos_in,
 				     struct file *file_out, loff_t pos_out,
 				     loff_t len, unsigned int remap_flags)
 {
+	struct inode *inode_in = file_inode(file_in);
+	struct inode *inode_out = file_inode(file_out);
+	struct ocfs2_super *osb = OCFS2_SB(inode_in->i_sb);
+	struct buffer_head *in_bh = NULL, *out_bh = NULL;
+	bool same_inode = (inode_in == inode_out);
+	loff_t remapped = 0;
+	ssize_t ret;
+
 	if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY))
 		return -EINVAL;
+	if (!ocfs2_refcount_tree(osb))
+		return -EOPNOTSUPP;
+	if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb))
+		return -EROFS;
 
-	return ocfs2_reflink_remap_range(file_in, pos_in, file_out, pos_out,
-			len, remap_flags);
+	/* Lock both files against IO */
+	ret = ocfs2_reflink_inodes_lock(inode_in, &in_bh, inode_out, &out_bh);
+	if (ret)
+		return ret;
+
+	/* Check file eligibility and prepare for block sharing. */
+	ret = -EINVAL;
+	if ((OCFS2_I(inode_in)->ip_flags & OCFS2_INODE_SYSTEM_FILE) ||
+	    (OCFS2_I(inode_out)->ip_flags & OCFS2_INODE_SYSTEM_FILE))
+		goto out_unlock;
+
+	ret = generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out,
+			&len, remap_flags);
+	if (ret < 0 || len == 0)
+		goto out_unlock;
+
+	/* Lock out changes to the allocation maps and remap. */
+	down_write(&OCFS2_I(inode_in)->ip_alloc_sem);
+	if (!same_inode)
+		down_write_nested(&OCFS2_I(inode_out)->ip_alloc_sem,
+				  SINGLE_DEPTH_NESTING);
+
+	/* Zap any page cache for the destination file's range. */
+	truncate_inode_pages_range(&inode_out->i_data,
+				   round_down(pos_out, PAGE_SIZE),
+				   round_up(pos_out + len, PAGE_SIZE) - 1);
+
+	remapped = ocfs2_reflink_remap_blocks(inode_in, in_bh, pos_in,
+			inode_out, out_bh, pos_out, len);
+	up_write(&OCFS2_I(inode_in)->ip_alloc_sem);
+	if (!same_inode)
+		up_write(&OCFS2_I(inode_out)->ip_alloc_sem);
+	if (remapped < 0) {
+		ret = remapped;
+		mlog_errno(ret);
+		goto out_unlock;
+	}
+
+	/*
+	 * Empty the extent map so that we may get the right extent
+	 * record from the disk.
+	 */
+	ocfs2_extent_map_trunc(inode_in, 0);
+	ocfs2_extent_map_trunc(inode_out, 0);
+
+	ret = ocfs2_reflink_update_dest(inode_out, out_bh, pos_out + len);
+	if (ret) {
+		mlog_errno(ret);
+		goto out_unlock;
+	}
+
+out_unlock:
+	ocfs2_reflink_inodes_unlock(inode_in, in_bh, inode_out, out_bh);
+	return remapped > 0 ? remapped : ret;
 }
 
 const struct inode_operations ocfs2_file_iops = {
diff --git a/fs/ocfs2/refcounttree.c b/fs/ocfs2/refcounttree.c
index c7409578657b..dc66b80585ec 100644
--- a/fs/ocfs2/refcounttree.c
+++ b/fs/ocfs2/refcounttree.c
@@ -4468,9 +4468,9 @@ int ocfs2_reflink_ioctl(struct inode *inode,
 }
 
 /* Update destination inode size, if necessary. */
-static int ocfs2_reflink_update_dest(struct inode *dest,
-				     struct buffer_head *d_bh,
-				     loff_t newlen)
+int ocfs2_reflink_update_dest(struct inode *dest,
+			      struct buffer_head *d_bh,
+			      loff_t newlen)
 {
 	handle_t *handle;
 	int ret;
@@ -4621,13 +4621,13 @@ static loff_t ocfs2_reflink_remap_extent(struct inode
*s_inode,
 }
 
 /* Set up refcount tree and remap s_inode to t_inode. */
-static loff_t ocfs2_reflink_remap_blocks(struct inode *s_inode,
-					 struct buffer_head *s_bh,
-					 loff_t pos_in,
-					 struct inode *t_inode,
-					 struct buffer_head *t_bh,
-					 loff_t pos_out,
-					 loff_t len)
+loff_t ocfs2_reflink_remap_blocks(struct inode *s_inode,
+				  struct buffer_head *s_bh,
+				  loff_t pos_in,
+				  struct inode *t_inode,
+				  struct buffer_head *t_bh,
+				  loff_t pos_out,
+				  loff_t len)
 {
 	struct ocfs2_cached_dealloc_ctxt dealloc;
 	struct ocfs2_super *osb;
@@ -4720,10 +4720,10 @@ static loff_t ocfs2_reflink_remap_blocks(struct inode
*s_inode,
 }
 
 /* Lock an inode and grab a bh pointing to the inode. */
-static int ocfs2_reflink_inodes_lock(struct inode *s_inode,
-				     struct buffer_head **bh1,
-				     struct inode *t_inode,
-				     struct buffer_head **bh2)
+int ocfs2_reflink_inodes_lock(struct inode *s_inode,
+			      struct buffer_head **bh1,
+			      struct inode *t_inode,
+			      struct buffer_head **bh2)
 {
 	struct inode *inode1;
 	struct inode *inode2;
@@ -4808,10 +4808,10 @@ static int ocfs2_reflink_inodes_lock(struct inode
*s_inode,
 }
 
 /* Unlock both inodes and release buffers. */
-static void ocfs2_reflink_inodes_unlock(struct inode *s_inode,
-					struct buffer_head *s_bh,
-					struct inode *t_inode,
-					struct buffer_head *t_bh)
+void ocfs2_reflink_inodes_unlock(struct inode *s_inode,
+				 struct buffer_head *s_bh,
+				 struct inode *t_inode,
+				 struct buffer_head *t_bh)
 {
 	ocfs2_inode_unlock(s_inode, 1);
 	ocfs2_rw_unlock(s_inode, 1);
@@ -4823,80 +4823,3 @@ static void ocfs2_reflink_inodes_unlock(struct inode
*s_inode,
 	}
 	unlock_two_nondirectories(s_inode, t_inode);
 }
-
-/* Link a range of blocks from one file to another. */
-loff_t ocfs2_reflink_remap_range(struct file *file_in,
-				 loff_t pos_in,
-				 struct file *file_out,
-				 loff_t pos_out,
-				 loff_t len,
-				 unsigned int remap_flags)
-{
-	struct inode *inode_in = file_inode(file_in);
-	struct inode *inode_out = file_inode(file_out);
-	struct ocfs2_super *osb = OCFS2_SB(inode_in->i_sb);
-	struct buffer_head *in_bh = NULL, *out_bh = NULL;
-	bool same_inode = (inode_in == inode_out);
-	loff_t remapped = 0;
-	ssize_t ret;
-
-	if (!ocfs2_refcount_tree(osb))
-		return -EOPNOTSUPP;
-	if (ocfs2_is_hard_readonly(osb) || ocfs2_is_soft_readonly(osb))
-		return -EROFS;
-
-	/* Lock both files against IO */
-	ret = ocfs2_reflink_inodes_lock(inode_in, &in_bh, inode_out, &out_bh);
-	if (ret)
-		return ret;
-
-	/* Check file eligibility and prepare for block sharing. */
-	ret = -EINVAL;
-	if ((OCFS2_I(inode_in)->ip_flags & OCFS2_INODE_SYSTEM_FILE) ||
-	    (OCFS2_I(inode_out)->ip_flags & OCFS2_INODE_SYSTEM_FILE))
-		goto out_unlock;
-
-	ret = generic_remap_file_range_prep(file_in, pos_in, file_out, pos_out,
-			&len, remap_flags);
-	if (ret < 0 || len == 0)
-		goto out_unlock;
-
-	/* Lock out changes to the allocation maps and remap. */
-	down_write(&OCFS2_I(inode_in)->ip_alloc_sem);
-	if (!same_inode)
-		down_write_nested(&OCFS2_I(inode_out)->ip_alloc_sem,
-				  SINGLE_DEPTH_NESTING);
-
-	/* Zap any page cache for the destination file's range. */
-	truncate_inode_pages_range(&inode_out->i_data,
-				   round_down(pos_out, PAGE_SIZE),
-				   round_up(pos_out + len, PAGE_SIZE) - 1);
-
-	remapped = ocfs2_reflink_remap_blocks(inode_in, in_bh, pos_in,
-			inode_out, out_bh, pos_out, len);
-	up_write(&OCFS2_I(inode_in)->ip_alloc_sem);
-	if (!same_inode)
-		up_write(&OCFS2_I(inode_out)->ip_alloc_sem);
-	if (remapped < 0) {
-		ret = remapped;
-		mlog_errno(ret);
-		goto out_unlock;
-	}
-
-	/*
-	 * Empty the extent map so that we may get the right extent
-	 * record from the disk.
-	 */
-	ocfs2_extent_map_trunc(inode_in, 0);
-	ocfs2_extent_map_trunc(inode_out, 0);
-
-	ret = ocfs2_reflink_update_dest(inode_out, out_bh, pos_out + len);
-	if (ret) {
-		mlog_errno(ret);
-		goto out_unlock;
-	}
-
-out_unlock:
-	ocfs2_reflink_inodes_unlock(inode_in, in_bh, inode_out, out_bh);
-	return remapped > 0 ? remapped : ret;
-}
diff --git a/fs/ocfs2/refcounttree.h b/fs/ocfs2/refcounttree.h
index 9e64daba395d..e9e862be4a1e 100644
--- a/fs/ocfs2/refcounttree.h
+++ b/fs/ocfs2/refcounttree.h
@@ -115,11 +115,23 @@ int ocfs2_reflink_ioctl(struct inode *inode,
 			const char __user *oldname,
 			const char __user *newname,
 			bool preserve);
-loff_t ocfs2_reflink_remap_range(struct file *file_in,
-				 loff_t pos_in,
-				 struct file *file_out,
-				 loff_t pos_out,
-				 loff_t len,
-				 unsigned int remap_flags);
+loff_t ocfs2_reflink_remap_blocks(struct inode *s_inode,
+				  struct buffer_head *s_bh,
+				  loff_t pos_in,
+				  struct inode *t_inode,
+				  struct buffer_head *t_bh,
+				  loff_t pos_out,
+				  loff_t len);
+int ocfs2_reflink_inodes_lock(struct inode *s_inode,
+			      struct buffer_head **bh1,
+			      struct inode *t_inode,
+			      struct buffer_head **bh2);
+void ocfs2_reflink_inodes_unlock(struct inode *s_inode,
+				 struct buffer_head *s_bh,
+				 struct inode *t_inode,
+				 struct buffer_head *t_bh);
+int ocfs2_reflink_update_dest(struct inode *dest,
+			      struct buffer_head *d_bh,
+			      loff_t newlen);
 
 #endif /* OCFS2_REFCOUNTTREE_H */

From: Darrick J. Wong <darrick.wong at oracle.com>

Prior to remapping blocks, it is necessary to remove pages from the
destination file's page cache.  Unfortunately, the truncation is not
aggressive enough -- if page size > block size, we'll end up zeroing
subpage blocks instead of removing them.  So, round the start offset
down and the end offset up to page boundaries.  We already wrote all
the dirty data so the larger range shouldn't be a problem.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
Reviewed-by: Dave Chinner <dchinner at redhat.com>
---
 fs/xfs/xfs_reflink.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)


diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 9b1ea42c81d1..e8e86646bb4b 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -1369,8 +1369,9 @@ xfs_reflink_remap_prep(
 		goto out_unlock;
 
 	/* Zap any page cache for the destination file's range. */
-	truncate_inode_pages_range(&inode_out->i_data, pos_out,
-				   PAGE_ALIGN(pos_out + *len) - 1);
+	truncate_inode_pages_range(&inode_out->i_data,
+			round_down(pos_out, PAGE_SIZE),
+			round_up(pos_out + *len, PAGE_SIZE) - 1);
 
 	return 1;
 out_unlock:

From: Darrick J. Wong <darrick.wong at oracle.com>

Back when the XFS reflink code only supported clone_file_range, we were
only able to return zero or negative error codes to userspace.  However,
now that copy_file_range (which returns bytes copied) can use XFS'
clone_file_range, we have the opportunity to return partial results.
For example, if userspace sends a 1GB clone request and we run out of
space halfway through, we at least can tell userspace that we completed
512M of that request like a regular write.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
---
 fs/xfs/xfs_file.c    |    5 +----
 fs/xfs/xfs_reflink.c |   20 +++++++++++++++-----
 fs/xfs/xfs_reflink.h |    2 +-
 3 files changed, 17 insertions(+), 10 deletions(-)


diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 38fde4e11714..7d42ab8fe6e1 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -928,14 +928,11 @@ xfs_file_remap_range(
 	loff_t		len,
 	unsigned int	remap_flags)
 {
-	int		ret;
-
 	if (remap_flags & ~(REMAP_FILE_DEDUP | REMAP_FILE_ADVISORY))
 		return -EINVAL;
 
-	ret = xfs_reflink_remap_range(file_in, pos_in, file_out, pos_out,
+	return xfs_reflink_remap_range(file_in, pos_in, file_out, pos_out,
 			len, remap_flags);
-	return ret < 0 ? ret : len;
 }
 
 STATIC int
diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index e8e86646bb4b..af3368862c56 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -1123,6 +1123,7 @@ xfs_reflink_remap_blocks(
 	struct xfs_inode	*dest,
 	xfs_fileoff_t		destoff,
 	xfs_filblks_t		len,
+	xfs_filblks_t		*remapped_len,
 	xfs_off_t		new_isize)
 {
 	struct xfs_bmbt_irec	imap;
@@ -1130,6 +1131,7 @@ xfs_reflink_remap_blocks(
 	int			error = 0;
 	xfs_filblks_t		range_len;
 
+	*remapped_len = 0;
 	/* drange = (destoff, destoff + len); srange = (srcoff, srcoff + len) */
 	while (len) {
 		uint		lock_mode;
@@ -1168,6 +1170,7 @@ xfs_reflink_remap_blocks(
 		srcoff += range_len;
 		destoff += range_len;
 		len -= range_len;
+		*remapped_len += range_len;
 	}
 
 	return 0;
@@ -1382,7 +1385,7 @@ xfs_reflink_remap_prep(
 /*
  * Link a range of blocks from one file to another.
  */
-int
+loff_t
 xfs_reflink_remap_range(
 	struct file		*file_in,
 	loff_t			pos_in,
@@ -1397,9 +1400,10 @@ xfs_reflink_remap_range(
 	struct xfs_inode	*dest = XFS_I(inode_out);
 	struct xfs_mount	*mp = src->i_mount;
 	xfs_fileoff_t		sfsbno, dfsbno;
-	xfs_filblks_t		fsblen;
+	xfs_filblks_t		fsblen, remappedfsb = 0;
+	loff_t			remapped_bytes = 0;
 	xfs_extlen_t		cowextsize;
-	ssize_t			ret;
+	int			ret;
 
 	if (!xfs_sb_version_hasreflink(&mp->m_sb))
 		return -EOPNOTSUPP;
@@ -1415,11 +1419,17 @@ xfs_reflink_remap_range(
 
 	trace_xfs_reflink_remap_range(src, pos_in, len, dest, pos_out);
 
+	if (len == 0) {
+		ret = 0;
+		goto out_unlock;
+	}
+
 	dfsbno = XFS_B_TO_FSBT(mp, pos_out);
 	sfsbno = XFS_B_TO_FSBT(mp, pos_in);
 	fsblen = XFS_B_TO_FSB(mp, len);
 	ret = xfs_reflink_remap_blocks(src, sfsbno, dest, dfsbno, fsblen,
-			pos_out + len);
+			&remappedfsb, pos_out + len);
+	remapped_bytes = min_t(loff_t, len, XFS_FSB_TO_B(mp, remappedfsb));
 	if (ret)
 		goto out_unlock;
 
@@ -1442,7 +1452,7 @@ xfs_reflink_remap_range(
 	xfs_reflink_remap_unlock(file_in, file_out);
 	if (ret)
 		trace_xfs_reflink_remap_range_error(dest, ret, _RET_IP_);
-	return ret;
+	return remapped_bytes > 0 ? remapped_bytes : ret;
 }
 
 /*
diff --git a/fs/xfs/xfs_reflink.h b/fs/xfs/xfs_reflink.h
index c3c46c276fe1..cbc26ff79a8f 100644
--- a/fs/xfs/xfs_reflink.h
+++ b/fs/xfs/xfs_reflink.h
@@ -27,7 +27,7 @@ extern int xfs_reflink_cancel_cow_range(struct xfs_inode *ip,
xfs_off_t offset,
 extern int xfs_reflink_end_cow(struct xfs_inode *ip, xfs_off_t offset,
 		xfs_off_t count);
 extern int xfs_reflink_recover_cow(struct xfs_mount *mp);
-extern int xfs_reflink_remap_range(struct file *file_in, loff_t pos_in,
+extern loff_t xfs_reflink_remap_range(struct file *file_in, loff_t pos_in,
 		struct file *file_out, loff_t pos_out, loff_t len,
 		unsigned int remap_flags);
 extern int xfs_reflink_inode_has_shared_extents(struct xfs_trans *tp,

From: Darrick J. Wong <darrick.wong at oracle.com>

Now that we've moved the partial EOF block checks to the VFS helpers, we
can remove the redundant functionality from XFS.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
Reviewed-by: Dave Chinner <dchinner at redhat.com>
---
 fs/xfs/xfs_reflink.c |   19 -------------------
 1 file changed, 19 deletions(-)


diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index af3368862c56..755d4a9446e3 100644
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -1307,7 +1307,6 @@ xfs_reflink_remap_prep(
 	struct inode		*inode_out = file_inode(file_out);
 	struct xfs_inode	*dest = XFS_I(inode_out);
 	bool			same_inode = (inode_in == inode_out);
-	u64			blkmask = i_blocksize(inode_in) - 1;
 	ssize_t			ret;
 
 	/* Lock both files against IO */
@@ -1335,24 +1334,6 @@ xfs_reflink_remap_prep(
 	if (ret < 0 || *len == 0)
 		goto out_unlock;
 
-	/*
-	 * If the dedupe data matches, chop off the partial EOF block
-	 * from the source file so we don't try to dedupe the partial
-	 * EOF block.
-	 */
-	if (remap_flags & REMAP_FILE_DEDUP) {
-		*len &= ~blkmask;
-	} else if (*len & blkmask) {
-		/*
-		 * The user is attempting to share a partial EOF block,
-		 * if it's inside the destination EOF then reject it.
-		 */
-		if (pos_out + *len < i_size_read(inode_out)) {
-			ret = -EINVAL;
-			goto out_unlock;
-		}
-	}
-
 	/* Attach dquots to dest inode before changing block map */
 	ret = xfs_qm_dqattach(dest);
 	if (ret)