Hi,
Any comment on this patch?
Without it, btrfs will always fail for generic/387.
Thanks,
Qu
At 09/07/2016 08:17 PM, Wang Xiaoguang wrote:
Below test script can reveal this bug:
dd if=/dev/zero of=fs.img bs=$((1024*1024)) count=100
dev=$(losetup --show -f fs.img)
mkdir -p /mnt/mntpoint
mkfs.btrfs -f $dev
mount $dev /mnt/mntpoint
cd /mnt/mntpoint
echo "workdir is: /mnt/mntpoint"
blocksize=$((128 * 1024))
dd if=/dev/zero of=testfile bs=$blocksize count=1
sync
count=$((17*1024*1024*1024/blocksize))
echo "file size is:" $((count*blocksize))
for ((i = 1; i <= $count; i++)); do
dst_offset=$((blocksize * i))
xfs_io -f -c "reflink testfile 0 $dst_offset $blocksize"\
testfile > /dev/null
done
sync
truncate --size 0 testfile
The last truncate operation will fail for ENOSPC reason, but indeed
it should not fail.
In btrfs_truncate(), we use a temporary block_rsv to do truncate
operation. With every btrfs_truncate_inode_items() call, we migrate space
to this block_rsv, but forget to cleanup previous reservation, which
will make this block_rsv's reserved bytes keep growing, and this reserved
space will only be released in the end of btrfs_truncate(), this metadata
leak will impact other's metadata reservation. In this case, it's
"btrfs_start_transaction(root, 2);" fails for enospc error, which make
this truncate operation fail.
Call btrfs_block_rsv_release() to fix this bug.
Signed-off-by: Wang Xiaoguang <[email protected]>
---
fs/btrfs/inode.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index e6811c4..40f0762 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -9206,6 +9206,7 @@ static int btrfs_truncate(struct inode *inode)
break;
}
+ btrfs_block_rsv_release(root, rsv, -1);
ret = btrfs_block_rsv_migrate(&root->fs_info->trans_block_rsv,
rsv, min_size, 0);
BUG_ON(ret); /* shouldn't happen */
--
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