thr3ads.net - Ocfs2 devel - [Ocfs2-devel] vfs/xfs: directio updates to ease COW handling V2 [Feb 2016]

If this information is useful, please help other people find it:
Share via:

Christoph Hellwig

2016-Feb-03 18:40 UTC

[Ocfs2-devel] vfs/xfs: directio updates to ease COW handling V2

See http://www.infradead.org/rpr.html

The first patch ensures ->end_io is always called for direct I/O requests
that pass it in, even if there was a zero length write, or if an error
occured.  The existing users have been updated to ignore it, but XFS
will make use of it in the future, and a comment in ext4 suggests it
might be useful for it as well.

The other two simplify the XFS direct I/O code.

Changes since V1:
 - allow ->end_io to return errors
 - a comment spelling fix

Christoph Hellwig

2016-Feb-03 18:40 UTC

head link

[Ocfs2-devel] [PATCH 1/3] direct-io: always call ->end_io if non-NULL

See http://www.infradead.org/rpr.html

This way we can pass back errors to the file system, and allow for
cleanup required for all direct I/O invocations.

Also allow the ->end_io handlers to return errors on their own, so that
I/O completion errors can be passed on to the callers.

Signed-off-by: Christoph Hellwig <hch at lst.de>
---
 fs/dax.c           |  9 +++++++--
 fs/direct-io.c     |  9 +++++++--
 fs/ext4/inode.c    |  9 +++++++--
 fs/ocfs2/aops.c    |  7 ++++++-
 fs/xfs/xfs_aops.c  | 13 +++++++------
 include/linux/fs.h |  2 +-
 6 files changed, 35 insertions(+), 14 deletions(-)

diff --git a/fs/dax.c b/fs/dax.c
index 4fd6b0c..e38b2c5 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -267,8 +267,13 @@ ssize_t dax_do_io(struct kiocb *iocb, struct inode *inode,
 	if ((flags & DIO_LOCKING) && iov_iter_rw(iter) == READ)
 		inode_unlock(inode);
 
-	if ((retval > 0) && end_io)
-		end_io(iocb, pos, retval, bh.b_private);
+	if (end_io) {
+		int err;
+
+		err = end_io(iocb, pos, retval, bh.b_private);
+		if (err)
+			retval = err;
+	}
 
 	if (!(flags & DIO_SKIP_DIO_COUNT))
 		inode_dio_end(inode);
diff --git a/fs/direct-io.c b/fs/direct-io.c
index 1b2f7ff..9c6f885 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -253,8 +253,13 @@ static ssize_t dio_complete(struct dio *dio, loff_t offset,
ssize_t ret,
 	if (ret == 0)
 		ret = transferred;
 
-	if (dio->end_io && dio->result)
-		dio->end_io(dio->iocb, offset, transferred, dio->private);
+	if (dio->end_io) {
+		int err;
+
+		err = dio->end_io(dio->iocb, offset, ret, dio->private);
+		if (err)
+			ret = err;
+	}
 
 	if (!(dio->flags & DIO_SKIP_DIO_COUNT))
 		inode_dio_end(dio->inode);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 83bc8bf..9db04dd 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3161,14 +3161,17 @@ out:
 }
 #endif
 
-static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
+static int ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
 			    ssize_t size, void *private)
 {
         ext4_io_end_t *io_end = iocb->private;
 
+	if (size <= 0)
+		return 0;
+
 	/* if not async direct IO just return */
 	if (!io_end)
-		return;
+		return 0;
 
 	ext_debug("ext4_end_io_dio(): io_end 0x%p "
 		  "for inode %lu, iocb 0x%p, offset %llu, size %zd\n",
@@ -3179,6 +3182,8 @@ static void ext4_end_io_dio(struct kiocb *iocb, loff_t
offset,
 	io_end->offset = offset;
 	io_end->size = size;
 	ext4_put_io_end(io_end);
+
+	return 0;
 }
 
 /*
diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index 794fd15..5dcc5f5 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -620,7 +620,7 @@ bail:
  * particularly interested in the aio/dio case.  We use the rw_lock DLM lock
  * to protect io on one node from truncation on another.
  */
-static void ocfs2_dio_end_io(struct kiocb *iocb,
+static int ocfs2_dio_end_io(struct kiocb *iocb,
 			     loff_t offset,
 			     ssize_t bytes,
 			     void *private)
@@ -628,6 +628,9 @@ static void ocfs2_dio_end_io(struct kiocb *iocb,
 	struct inode *inode = file_inode(iocb->ki_filp);
 	int level;
 
+	if (bytes <= 0)
+		return 0;
+
 	/* this io's submitter should not have unlocked this before we could */
 	BUG_ON(!ocfs2_iocb_is_rw_locked(iocb));
 
@@ -644,6 +647,8 @@ static void ocfs2_dio_end_io(struct kiocb *iocb,
 		level = ocfs2_iocb_rw_locked_level(iocb);
 		ocfs2_rw_unlock(inode, level);
 	}
+
+	return 0;
 }
 
 static int ocfs2_releasepage(struct page *page, gfp_t wait)
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 379c089..295aaff 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -1645,7 +1645,7 @@ out_end_io:
  * case the completion can be called in interrupt context, whereas if we have
an
  * ioend we will always be called in task context (i.e. from a workqueue).
  */
-STATIC void
+STATIC int
 xfs_end_io_direct_write(
 	struct kiocb		*iocb,
 	loff_t			offset,
@@ -1655,15 +1655,19 @@ xfs_end_io_direct_write(
 	struct inode		*inode = file_inode(iocb->ki_filp);
 	struct xfs_ioend	*ioend = private;
 
+	if (size <= 0)
+		return 0;
+
 	trace_xfs_gbmap_direct_endio(XFS_I(inode), offset, size,
 				     ioend ? ioend->io_type : 0, NULL);
 
 	if (!ioend) {
 		ASSERT(offset + size <= i_size_read(inode));
-		return;
+		return 0;
 	}
 
 	__xfs_end_io_direct_write(inode, ioend, offset, size);
+	return 0;
 }
 
 static inline ssize_t
@@ -1672,10 +1676,7 @@ xfs_vm_do_dio(
 	struct kiocb		*iocb,
 	struct iov_iter		*iter,
 	loff_t			offset,
-	void			(*endio)(struct kiocb	*iocb,
-					 loff_t		offset,
-					 ssize_t	size,
-					 void		*private),
+	dio_iodone_t		endio,
 	int			flags)
 {
 	struct block_device	*bdev;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 1a20462..d7f37bf 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -70,7 +70,7 @@ extern int sysctl_protected_hardlinks;
 struct buffer_head;
 typedef int (get_block_t)(struct inode *inode, sector_t iblock,
 			struct buffer_head *bh_result, int create);
-typedef void (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
+typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
 			ssize_t bytes, void *private);
 typedef void (dax_iodone_t)(struct buffer_head *bh_map, int uptodate);
 
-- 
2.1.4

Christoph Hellwig

2016-Feb-03 18:40 UTC

head link

[Ocfs2-devel] [PATCH 2/3] xfs: don't use ioends for direct write completions

See http://www.infradead.org/rpr.html

We only need to communicate two bits of information to the direct I/O
completion handler:

 (1) do we need to convert any unwritten extents in the range
 (2) do we need to check if we need to update the inode size based
     on the range passed to the completion handler

We can use the private data passed to the get_block handler and the
completion handler as a simple bitmask to communicate this information
instead of the current complicated infrastructure reusing the ioends
from the buffer I/O path, and thus avoiding a memory allocation and
a context switch for any non-trivial direct write.  As a nice side
effect we also decouple the direct I/O path implementation from that
of the buffered I/O path.

Signed-off-by: Christoph Hellwig <hch at lst.de>
Reviewed-by: Brian Foster <bfoster at redhat.com>
---
 fs/xfs/xfs_aops.c  | 216 ++++++++++++++++++-----------------------------------
 fs/xfs/xfs_trace.h |   9 +--
 2 files changed, 75 insertions(+), 150 deletions(-)

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 295aaff..f008a4f 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -36,6 +36,10 @@
 #include <linux/pagevec.h>
 #include <linux/writeback.h>
 
+/* flags for direct write completions */
+#define XFS_DIO_FLAG_UNWRITTEN	(1 << 0)
+#define XFS_DIO_FLAG_APPEND	(1 << 1)
+
 void
 xfs_count_page_state(
 	struct page		*page,
@@ -1238,27 +1242,8 @@ xfs_vm_releasepage(
 }
 
 /*
- * When we map a DIO buffer, we may need to attach an ioend that describes the
- * type of write IO we are doing. This passes to the completion function the
- * operations it needs to perform. If the mapping is for an overwrite wholly
- * within the EOF then we don't need an ioend and so we don't allocate
one.
- * This avoids the unnecessary overhead of allocating and freeing ioends for
- * workloads that don't require transactions on IO completion.
- *
- * If we get multiple mappings in a single IO, we might be mapping different
- * types. But because the direct IO can only have a single private pointer, we
- * need to ensure that:
- *
- * a) i) the ioend spans the entire region of unwritten mappings; or
- *    ii) the ioend spans all the mappings that cross or are beyond EOF; and
- * b) if it contains unwritten extents, it is *permanently* marked as such
- *
- * We could do this by chaining ioends like buffered IO does, but we only
- * actually get one IO completion callback from the direct IO, and that spans
- * the entire IO regardless of how many mappings and IOs are needed to complete
- * the DIO. There is only going to be one reference to the ioend and its life
- * cycle is constrained by the DIO completion code. hence we don't need
- * reference counting here.
+ * When we map a DIO buffer, we may need to pass flags to
+ * xfs_end_io_direct_write to tell it what kind of write IO we are doing.
  *
  * Note that for DIO, an IO to the highest supported file block offset (i.e.
  * 2^63 - 1FSB bytes) will result in the offset + count overflowing a signed 64
@@ -1266,68 +1251,26 @@ xfs_vm_releasepage(
  * extending the file size. We won't know for sure until IO completion is
run
  * and the actual max write offset is communicated to the IO completion
  * routine.
- *
- * For DAX page faults, we are preparing to never see unwritten extents here,
- * nor should we ever extend the inode size. Hence we will soon have nothing to
- * do here for this case, ensuring we don't have to provide an IO
completion
- * callback to free an ioend that we don't actually need for a fault into
the
- * page at offset (2^63 - 1FSB) bytes.
  */
-
 static void
 xfs_map_direct(
 	struct inode		*inode,
 	struct buffer_head	*bh_result,
 	struct xfs_bmbt_irec	*imap,
-	xfs_off_t		offset,
-	bool			dax_fault)
+	xfs_off_t		offset)
 {
-	struct xfs_ioend	*ioend;
+	uintptr_t		*flags = (uintptr_t *)&bh_result->b_private;
 	xfs_off_t		size = bh_result->b_size;
-	int			type;
-
-	if (ISUNWRITTEN(imap))
-		type = XFS_IO_UNWRITTEN;
-	else
-		type = XFS_IO_OVERWRITE;
-
-	trace_xfs_gbmap_direct(XFS_I(inode), offset, size, type, imap);
-
-	if (dax_fault) {
-		ASSERT(type == XFS_IO_OVERWRITE);
-		trace_xfs_gbmap_direct_none(XFS_I(inode), offset, size, type,
-					    imap);
-		return;
-	}
 
-	if (bh_result->b_private) {
-		ioend = bh_result->b_private;
-		ASSERT(ioend->io_size > 0);
-		ASSERT(offset >= ioend->io_offset);
-		if (offset + size > ioend->io_offset + ioend->io_size)
-			ioend->io_size = offset - ioend->io_offset + size;
-
-		if (type == XFS_IO_UNWRITTEN && type != ioend->io_type)
-			ioend->io_type = XFS_IO_UNWRITTEN;
-
-		trace_xfs_gbmap_direct_update(XFS_I(inode), ioend->io_offset,
-					      ioend->io_size, ioend->io_type,
-					      imap);
-	} else if (type == XFS_IO_UNWRITTEN ||
-		   offset + size > i_size_read(inode) ||
-		   offset + size < 0) {
-		ioend = xfs_alloc_ioend(inode, type);
-		ioend->io_offset = offset;
-		ioend->io_size = size;
+	trace_xfs_get_blocks_map_direct(XFS_I(inode), offset, size,
+		ISUNWRITTEN(imap) ? XFS_IO_UNWRITTEN : XFS_IO_OVERWRITE, imap);
 
-		bh_result->b_private = ioend;
+	if (ISUNWRITTEN(imap)) {
+		*flags |= XFS_DIO_FLAG_UNWRITTEN;
+		set_buffer_defer_completion(bh_result);
+	} else if (offset + size > i_size_read(inode) || offset + size < 0) {
+		*flags |= XFS_DIO_FLAG_APPEND;
 		set_buffer_defer_completion(bh_result);
-
-		trace_xfs_gbmap_direct_new(XFS_I(inode), offset, size, type,
-					   imap);
-	} else {
-		trace_xfs_gbmap_direct_none(XFS_I(inode), offset, size, type,
-					    imap);
 	}
 }
 
@@ -1498,9 +1441,12 @@ __xfs_get_blocks(
 		if (ISUNWRITTEN(&imap))
 			set_buffer_unwritten(bh_result);
 		/* direct IO needs special help */
-		if (create && direct)
-			xfs_map_direct(inode, bh_result, &imap, offset,
-				       dax_fault);
+		if (create && direct) {
+			if (dax_fault)
+				ASSERT(!ISUNWRITTEN(&imap));
+			else
+				xfs_map_direct(inode, bh_result, &imap, offset);
+		}
 	}
 
 	/*
@@ -1570,42 +1516,50 @@ xfs_get_blocks_dax_fault(
 	return __xfs_get_blocks(inode, iblock, bh_result, create, true, true);
 }
 
-static void
-__xfs_end_io_direct_write(
-	struct inode		*inode,
-	struct xfs_ioend	*ioend,
+/*
+ * Complete a direct I/O write request.
+ *
+ * xfs_map_direct passes us some flags in the private data to tell us what to
+ * do.  If no flags are set, then the write IO is an overwrite wholly within
+ * the existing allocated file size and so there is nothing for us to do.
+ *
+ * Note that in this case the completion can be called in interrupt context,
+ * whereas if we have flags set we will always be called in task context
+ * (i.e. from a workqueue).
+ */
+STATIC int
+xfs_end_io_direct_write(
+	struct kiocb		*iocb,
 	loff_t			offset,
-	ssize_t			size)
+	ssize_t			size,
+	void			*private)
 {
-	struct xfs_mount	*mp = XFS_I(inode)->i_mount;
+	struct inode		*inode = file_inode(iocb->ki_filp);
+	struct xfs_inode	*ip = XFS_I(inode);
+	struct xfs_mount	*mp = ip->i_mount;
+	uintptr_t		flags = (uintptr_t)private;
+	int			error = 0;
 
-	if (XFS_FORCED_SHUTDOWN(mp) || ioend->io_error)
-		goto out_end_io;
+	trace_xfs_end_io_direct_write(ip, offset, size);
 
-	/*
-	 * dio completion end_io functions are only called on writes if more
-	 * than 0 bytes was written.
-	 */
-	ASSERT(size > 0);
+	if (XFS_FORCED_SHUTDOWN(mp))
+		return -EIO;
 
-	/*
-	 * The ioend only maps whole blocks, while the IO may be sector aligned.
-	 * Hence the ioend offset/size may not match the IO offset/size exactly.
-	 * Because we don't map overwrites within EOF into the ioend, the offset
-	 * may not match, but only if the endio spans EOF.  Either way, write
-	 * the IO sizes into the ioend so that completion processing does the
-	 * right thing.
-	 */
-	ASSERT(offset + size <= ioend->io_offset + ioend->io_size);
-	ioend->io_size = size;
-	ioend->io_offset = offset;
+	if (size <= 0)
+		return size;
 
 	/*
-	 * The ioend tells us whether we are doing unwritten extent conversion
+	 * The flags tell us whether we are doing unwritten extent conversions
 	 * or an append transaction that updates the on-disk file size. These
 	 * cases are the only cases where we should *potentially* be needing
 	 * to update the VFS inode size.
-	 *
+	 */
+	if (flags == 0) {
+		ASSERT(offset + size <= i_size_read(inode));
+		return 0;
+	}
+
+	/*
 	 * We need to update the in-core inode size here so that we don't end up
 	 * with the on-disk inode size being outside the in-core inode size. We
 	 * have no other method of updating EOF for AIO, so always do it here
@@ -1616,58 +1570,30 @@ __xfs_end_io_direct_write(
 	 * here can result in EOF moving backwards and Bad Things Happen when
 	 * that occurs.
 	 */
-	spin_lock(&XFS_I(inode)->i_flags_lock);
+	spin_lock(&ip->i_flags_lock);
 	if (offset + size > i_size_read(inode))
 		i_size_write(inode, offset + size);
-	spin_unlock(&XFS_I(inode)->i_flags_lock);
+	spin_unlock(&ip->i_flags_lock);
 
-	/*
-	 * If we are doing an append IO that needs to update the EOF on disk,
-	 * do the transaction reserve now so we can use common end io
-	 * processing. Stashing the error (if there is one) in the ioend will
-	 * result in the ioend processing passing on the error if it is
-	 * possible as we can't return it from here.
-	 */
-	if (ioend->io_type == XFS_IO_OVERWRITE)
-		ioend->io_error = xfs_setfilesize_trans_alloc(ioend);
+	if (flags & XFS_DIO_FLAG_UNWRITTEN) {
+		trace_xfs_end_io_direct_write_unwritten(ip, offset, size);
 
-out_end_io:
-	xfs_end_io(&ioend->io_work);
-	return;
-}
+		error = xfs_iomap_write_unwritten(ip, offset, size);
+	} else if (flags & XFS_DIO_FLAG_APPEND) {
+		struct xfs_trans *tp;
 
-/*
- * Complete a direct I/O write request.
- *
- * The ioend structure is passed from __xfs_get_blocks() to tell us what to do.
- * If no ioend exists (i.e. @private == NULL) then the write IO is an overwrite
- * wholly within the EOF and so there is nothing for us to do. Note that in
this
- * case the completion can be called in interrupt context, whereas if we have
an
- * ioend we will always be called in task context (i.e. from a workqueue).
- */
-STATIC int
-xfs_end_io_direct_write(
-	struct kiocb		*iocb,
-	loff_t			offset,
-	ssize_t			size,
-	void			*private)
-{
-	struct inode		*inode = file_inode(iocb->ki_filp);
-	struct xfs_ioend	*ioend = private;
+		trace_xfs_end_io_direct_write_append(ip, offset, size);
 
-	if (size <= 0)
-		return 0;
-
-	trace_xfs_gbmap_direct_endio(XFS_I(inode), offset, size,
-				     ioend ? ioend->io_type : 0, NULL);
-
-	if (!ioend) {
-		ASSERT(offset + size <= i_size_read(inode));
-		return 0;
+		tp = xfs_trans_alloc(mp, XFS_TRANS_FSYNC_TS);
+		error = xfs_trans_reserve(tp, &M_RES(mp)->tr_fsyncts, 0, 0);
+		if (error) {
+			xfs_trans_cancel(tp);
+			return error;
+		}
+		error = xfs_setfilesize(ip, tp, offset, size);
 	}
 
-	__xfs_end_io_direct_write(inode, ioend, offset, size);
-	return 0;
+	return error;
 }
 
 static inline ssize_t
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 391d797..c8d5842 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -1296,11 +1296,7 @@ DEFINE_IOMAP_EVENT(xfs_map_blocks_found);
 DEFINE_IOMAP_EVENT(xfs_map_blocks_alloc);
 DEFINE_IOMAP_EVENT(xfs_get_blocks_found);
 DEFINE_IOMAP_EVENT(xfs_get_blocks_alloc);
-DEFINE_IOMAP_EVENT(xfs_gbmap_direct);
-DEFINE_IOMAP_EVENT(xfs_gbmap_direct_new);
-DEFINE_IOMAP_EVENT(xfs_gbmap_direct_update);
-DEFINE_IOMAP_EVENT(xfs_gbmap_direct_none);
-DEFINE_IOMAP_EVENT(xfs_gbmap_direct_endio);
+DEFINE_IOMAP_EVENT(xfs_get_blocks_map_direct);
 
 DECLARE_EVENT_CLASS(xfs_simple_io_class,
 	TP_PROTO(struct xfs_inode *ip, xfs_off_t offset, ssize_t count),
@@ -1340,6 +1336,9 @@ DEFINE_SIMPLE_IO_EVENT(xfs_unwritten_convert);
 DEFINE_SIMPLE_IO_EVENT(xfs_get_blocks_notfound);
 DEFINE_SIMPLE_IO_EVENT(xfs_setfilesize);
 DEFINE_SIMPLE_IO_EVENT(xfs_zero_eof);
+DEFINE_SIMPLE_IO_EVENT(xfs_end_io_direct_write);
+DEFINE_SIMPLE_IO_EVENT(xfs_end_io_direct_write_unwritten);
+DEFINE_SIMPLE_IO_EVENT(xfs_end_io_direct_write_append);
 
 DECLARE_EVENT_CLASS(xfs_itrunc_class,
 	TP_PROTO(struct xfs_inode *ip, xfs_fsize_t new_size),
-- 
2.1.4

Christoph Hellwig

2016-Feb-03 18:40 UTC

head link

[Ocfs2-devel] [PATCH 3/3] xfs: fold xfs_vm_do_dio into xfs_vm_direct_IO

See http://www.infradead.org/rpr.html

Signed-off-by: Christoph Hellwig <hch at lst.de>
Reviewed-by: Brian Foster <bfoster at redhat.com>
---
 fs/xfs/xfs_aops.c | 36 ++++++++++++++----------------------
 1 file changed, 14 insertions(+), 22 deletions(-)

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index f008a4f..8163910 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -1596,38 +1596,30 @@ xfs_end_io_direct_write(
 	return error;
 }
 
-static inline ssize_t
-xfs_vm_do_dio(
-	struct inode		*inode,
+STATIC ssize_t
+xfs_vm_direct_IO(
 	struct kiocb		*iocb,
 	struct iov_iter		*iter,
-	loff_t			offset,
-	dio_iodone_t		endio,
-	int			flags)
+	loff_t			offset)
 {
+	struct inode		*inode = iocb->ki_filp->f_mapping->host;
+	dio_iodone_t		*endio = NULL;
+	int			flags = 0;
 	struct block_device	*bdev;
 
-	if (IS_DAX(inode))
+	if (iov_iter_rw(iter) == WRITE) {
+		endio = xfs_end_io_direct_write;
+		flags = DIO_ASYNC_EXTEND;
+	}
+
+	if (IS_DAX(inode)) {
 		return dax_do_io(iocb, inode, iter, offset,
 				 xfs_get_blocks_direct, endio, 0);
+	}
 
 	bdev = xfs_find_bdev_for_inode(inode);
 	return  __blockdev_direct_IO(iocb, inode, bdev, iter, offset,
-				     xfs_get_blocks_direct, endio, NULL, flags);
-}
-
-STATIC ssize_t
-xfs_vm_direct_IO(
-	struct kiocb		*iocb,
-	struct iov_iter		*iter,
-	loff_t			offset)
-{
-	struct inode		*inode = iocb->ki_filp->f_mapping->host;
-
-	if (iov_iter_rw(iter) == WRITE)
-		return xfs_vm_do_dio(inode, iocb, iter, offset,
-				     xfs_end_io_direct_write, DIO_ASYNC_EXTEND);
-	return xfs_vm_do_dio(inode, iocb, iter, offset, NULL, 0);
+			xfs_get_blocks_direct, endio, NULL, flags);
 }
 
 /*
-- 
2.1.4

Jeff Moyer

2016-Feb-03 19:43 UTC

head link

[Ocfs2-devel] vfs/xfs: directio updates to ease COW handling V2

Hi, Christoph,

Can you explain a bit what you mean by easing COW handling?  Whenever I
see COW referenced near DIO, my mind always turns to g_u_p vs. fork.

Thanks!
Jeff

Christoph Hellwig <hch at lst.de> writes:
> See http://www.infradead.org/rpr.html
>
> The first patch ensures ->end_io is always called for direct I/O
requests
> that pass it in, even if there was a zero length write, or if an error
> occured.  The existing users have been updated to ignore it, but XFS
> will make use of it in the future, and a comment in ext4 suggests it
> might be useful for it as well.
>
> The other two simplify the XFS direct I/O code.
>
> Changes since V1:
>  - allow ->end_io to return errors
>  - a comment spelling fix
>
>
> --
> To unsubscribe from this list: send the line "unsubscribe
linux-fsdevel" in
> the body of a message to majordomo at vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Ocfs2 devel - Feb 2016 - vfs/xfs: directio updates to ease COW handling V2

[Ocfs2-devel] vfs/xfs: directio updates to ease COW handling V2

[Ocfs2-devel] [PATCH 1/3] direct-io: always call ->end_io if non-NULL

[Ocfs2-devel] [PATCH 2/3] xfs: don't use ioends for direct write completions

[Ocfs2-devel] [PATCH 3/3] xfs: fold xfs_vm_do_dio into xfs_vm_direct_IO

[Ocfs2-devel] vfs/xfs: directio updates to ease COW handling V2