| Message ID | 20190916120239.12570-2-wqu@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2,1/2] btrfs: qgroup: Fix the wrong target io_tree when freeing reserved data space | expand |
On 16.09.19 г. 15:02 ч., Qu Wenruo wrote: > [BUG] > The following script can cause btrfs qgroup data space leak: > > mkfs.btrfs -f $dev > mount $dev -o nospace_cache $mnt > > btrfs subv create $mnt/subv > btrfs quota en $mnt > btrfs quota rescan -w $mnt > btrfs qgroup limit 128m $mnt/subv > > for (( i = 0; i < 3; i++)); do > # Create 3 64M holes for latter fallocate to fail > truncate -s 192m $mnt/subv/file > xfs_io -c "pwrite 64m 4k" $mnt/subv/file > /dev/null > xfs_io -c "pwrite 128m 4k" $mnt/subv/file > /dev/null > sync > > # it's supposed to fail, and each failure will leak at least 64M > # data space > xfs_io -f -c "falloc 0 192m" $mnt/subv/file &> /dev/null > rm $mnt/subv/file > sync > done > > # Shouldn't fail after we removed the file > xfs_io -f -c "falloc 0 64m" $mnt/subv/file Was this sent as a separate fstest case? <snip>
On 2019/9/24 下午5:12, Nikolay Borisov wrote: > > > On 16.09.19 г. 15:02 ч., Qu Wenruo wrote: >> [BUG] >> The following script can cause btrfs qgroup data space leak: >> >> mkfs.btrfs -f $dev >> mount $dev -o nospace_cache $mnt >> >> btrfs subv create $mnt/subv >> btrfs quota en $mnt >> btrfs quota rescan -w $mnt >> btrfs qgroup limit 128m $mnt/subv >> >> for (( i = 0; i < 3; i++)); do >> # Create 3 64M holes for latter fallocate to fail >> truncate -s 192m $mnt/subv/file >> xfs_io -c "pwrite 64m 4k" $mnt/subv/file > /dev/null >> xfs_io -c "pwrite 128m 4k" $mnt/subv/file > /dev/null >> sync >> >> # it's supposed to fail, and each failure will leak at least 64M >> # data space >> xfs_io -f -c "falloc 0 192m" $mnt/subv/file &> /dev/null >> rm $mnt/subv/file >> sync >> done >> >> # Shouldn't fail after we removed the file >> xfs_io -f -c "falloc 0 64m" $mnt/subv/file > > Was this sent as a separate fstest case? Yep. https://patchwork.kernel.org/patch/11145871/ Thanks, Qu > > <snip> >
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c index 64bdc3e3652d..59f6a9981087 100644 --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -3448,6 +3448,9 @@ int btrfs_qgroup_reserve_data(struct inode *inode, while ((unode = ulist_next(&reserved->range_changed, &uiter))) clear_extent_bit(&BTRFS_I(inode)->io_tree, unode->val, unode->aux, EXTENT_QGROUP_RESERVED, 0, 0, NULL); + /* Also free data bytes of already reserved one */ + btrfs_qgroup_free_refroot(root->fs_info, root->root_key.objectid, + orig_reserved, BTRFS_QGROUP_RSV_DATA); extent_changeset_release(reserved); return ret; }
[BUG] The following script can cause btrfs qgroup data space leak: mkfs.btrfs -f $dev mount $dev -o nospace_cache $mnt btrfs subv create $mnt/subv btrfs quota en $mnt btrfs quota rescan -w $mnt btrfs qgroup limit 128m $mnt/subv for (( i = 0; i < 3; i++)); do # Create 3 64M holes for latter fallocate to fail truncate -s 192m $mnt/subv/file xfs_io -c "pwrite 64m 4k" $mnt/subv/file > /dev/null xfs_io -c "pwrite 128m 4k" $mnt/subv/file > /dev/null sync # it's supposed to fail, and each failure will leak at least 64M # data space xfs_io -f -c "falloc 0 192m" $mnt/subv/file &> /dev/null rm $mnt/subv/file sync done # Shouldn't fail after we removed the file xfs_io -f -c "falloc 0 64m" $mnt/subv/file [CAUSE] Btrfs qgroup data reserve code allow multiple reservations to happen on a single extent_changeset: E.g: btrfs_qgroup_reserve_data(inode, &data_reserved, 0, SZ_1M); btrfs_qgroup_reserve_data(inode, &data_reserved, SZ_1M, SZ_2M); btrfs_qgroup_reserve_data(inode, &data_reserved, 0, SZ_4M); Btrfs qgroup code has its internal tracking to make sure we don't double-reserve in above example. The only pattern utlizing this feature is in the main while loop of btrfs_fallocate() function. However btrfs_qgroup_reserve_data()'s error handling has a bug in that on error it clears all ranges in the io_tree with EXTENT_QGROUP_RESERVED flag but doesn't free previously reserved bytes. This bug has a two fold effect: - Clearing EXTENT_QGROUP_RESERVED ranges This is the correct behavior, but it prevents btrfs_qgroup_check_reserved_leak() to catch the leakage as the detector is purely EXTENT_QGROUP_RESERVED flag based. - Leak the previously reserved data bytes. The bug manifests when N calls to btrfs_qgroup_reserve_data are made and the last one fails, leaking space reserved in the previous ones. [FIX] Also free previously reserved data bytes when btrfs_qgroup_reserve_data fails. Fixes: 524725537023 ("btrfs: qgroup: Introduce btrfs_qgroup_reserve_data function") Signed-off-by: Qu Wenruo <wqu@suse.com> --- Changelog: v2: - Commit message polishment Rephrase the multiple btrfs_qgroup_reserve_data() calls ability. Rephrase the effect of the bug. --- fs/btrfs/qgroup.c | 3 +++ 1 file changed, 3 insertions(+)