[PATCH] Btrfs: fix direct-io vs nodatacow

[PATCH] Btrfs: fix direct-io vs nodatacow

[Li Zefan]

To reproduce the bug:

  # mount -o nodatacow /dev/sda7 /mnt/
  # dd if=/dev/zero of=/mnt/tmp bs=4K count=1
  1+0 records in
  1+0 records out
  4096 bytes (4.1 kB) copied, 0.000136115 s, 30.1 MB/s
  # dd if=/dev/zero of=/mnt/tmp bs=4K count=1 conv=notrunc oflag=direct
  dd: writing `/mnt/tmp': Input/output error
  1+0 records in
  0+0 records out

btrfs_ordered_update_i_size() may return 1, but btrfs_endio_direct_write()
mistakenly takes it as an error.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
---
 fs/btrfs/inode.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 0ccc743..3bd35fe 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5785,8 +5785,7 @@ again:
 	if (test_bit(BTRFS_ORDERED_NOCOW, &ordered->flags)) {
 		ret = btrfs_ordered_update_i_size(inode, 0, ordered);
 		if (!ret)
-			ret = btrfs_update_inode(trans, root, inode);
-		err = ret;
+			err = btrfs_update_inode(trans, root, inode);
 		goto out;
 	}
 
-- 1.7.3.1 

Re: [PATCH] Btrfs: fix direct-io vs nodatacow

[David Sterba]

On Thu, Sep 08, 2011 at 10:26:51AM +0800, Li Zefan wrote:
> To reproduce the bug:
> 
>   # mount -o nodatacow /dev/sda7 /mnt/
>   # dd if=/dev/zero of=/mnt/tmp bs=4K count=1
>   1+0 records in
>   1+0 records out
>   4096 bytes (4.1 kB) copied, 0.000136115 s, 30.1 MB/s
>   # dd if=/dev/zero of=/mnt/tmp bs=4K count=1 conv=notrunc oflag=direct
>   dd: writing `/mnt/tmp': Input/output error
>   1+0 records in
>   0+0 records out
> 
> btrfs_ordered_update_i_size() may return 1, but btrfs_endio_direct_write()
> mistakenly takes it as an error.
> 
> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.cz>

> ---
>  fs/btrfs/inode.c |    3 +--
>  1 files changed, 1 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 0ccc743..3bd35fe 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -5785,8 +5785,7 @@ again:
>  	if (test_bit(BTRFS_ORDERED_NOCOW, &ordered->flags)) {
>  		ret = btrfs_ordered_update_i_size(inode, 0, ordered);
>  		if (!ret)
> -			ret = btrfs_update_inode(trans, root, inode);
> -		err = ret;
> +			err = btrfs_update_inode(trans, root, inode);
>  		goto out;
>  	}
>  
> -- 1.7.3.1 
> --
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