Miao Xie
2011-Aug-18 08:13 UTC
[PATCH 2/3] Btrfs: fix the file extent gap when doing direct IO
When we write some data to the place that is beyond the end of the file
in direct I/O mode, a data hole will be created. And Btrfs should insert
a file extent item that point to this hole into the fs tree. But unfortunately
Btrfs forgets doing it.
The following is a simple way to reproduce it:
# mkfs.btrfs /dev/sdc2
# mount /dev/sdc2 /test4
# touch /test4/a
# dd if=/dev/zero of=/test4/a seek=8 count=1 bs=4K oflag=direct
conv=nocreat,notrunc
# umount /test4
# btrfsck /dev/sdc2
root 5 inode 257 errors 100
Reported-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Tested-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
---
fs/btrfs/file.c | 16 ++++++++++------
1 files changed, 10 insertions(+), 6 deletions(-)
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 010aec8..a9c4636 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1073,12 +1073,6 @@ static noinline int prepare_pages(struct btrfs_root
*root, struct file *file,
start_pos = pos & ~((u64)root->sectorsize - 1);
last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;
- if (start_pos > inode->i_size) {
- err = btrfs_cont_expand(inode, i_size_read(inode), start_pos);
- if (err)
- return err;
- }
-
again:
for (i = 0; i < num_pages; i++) {
pages[i] = find_or_create_page(inode->i_mapping, index + i,
@@ -1336,6 +1330,7 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
struct inode *inode = fdentry(file)->d_inode;
struct btrfs_root *root = BTRFS_I(inode)->root;
loff_t *ppos = &iocb->ki_pos;
+ u64 start_pos;
ssize_t num_written = 0;
ssize_t err = 0;
size_t count, ocount;
@@ -1384,6 +1379,15 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb,
file_update_time(file);
BTRFS_I(inode)->sequence++;
+ start_pos = round_down(pos, root->sectorsize);
+ if (start_pos > i_size_read(inode)) {
+ err = btrfs_cont_expand(inode, i_size_read(inode), start_pos);
+ if (err) {
+ mutex_unlock(&inode->i_mutex);
+ goto out;
+ }
+ }
+
if (unlikely(file->f_flags & O_DIRECT)) {
num_written = __btrfs_direct_write(iocb, iov, nr_segs,
pos, ppos, count, ocount);
--
1.7.4
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Li Zefan
2011-Aug-24 05:14 UTC
Re: [PATCH 2/3] Btrfs: fix the file extent gap when doing direct IO
> diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c > index 010aec8..a9c4636 100644 > --- a/fs/btrfs/file.c > +++ b/fs/btrfs/file.c > @@ -1073,12 +1073,6 @@ static noinline int prepare_pages(struct btrfs_root *root, struct file *file, > start_pos = pos & ~((u64)root->sectorsize - 1); > last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT; > > - if (start_pos > inode->i_size) { > - err = btrfs_cont_expand(inode, i_size_read(inode), start_pos); > - if (err) > - return err; > - } > - > again: > for (i = 0; i < num_pages; i++) { > pages[i] = find_or_create_page(inode->i_mapping, index + i, > @@ -1336,6 +1330,7 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb, > struct inode *inode = fdentry(file)->d_inode; > struct btrfs_root *root = BTRFS_I(inode)->root; > loff_t *ppos = &iocb->ki_pos; > + u64 start_pos; > ssize_t num_written = 0; > ssize_t err = 0; > size_t count, ocount; > @@ -1384,6 +1379,15 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb, > file_update_time(file); > BTRFS_I(inode)->sequence++; > > + start_pos = round_down(pos, root->sectorsize); > + if (start_pos > i_size_read(inode)) {You changed the code to use i_size_read() instead of inode->i_size, which is not necessary since we''re holding i_mutex.> + err = btrfs_cont_expand(inode, i_size_read(inode), start_pos);So here we can also use inode->i_size directly.> + if (err) { > + mutex_unlock(&inode->i_mutex); > + goto out; > + } > + } > + > if (unlikely(file->f_flags & O_DIRECT)) { > num_written = __btrfs_direct_write(iocb, iov, nr_segs, > pos, ppos, count, ocount);-- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html