| Message ID | 20190916120239.12570-1-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] > Under the follow case with qgroup enabled, if some error happened after > we have reserved delalloc space, then in error handling path, we could > cause qgroup data space leakage: > > From btrfs_truncate_block() in inode.c: > > ret = btrfs_delalloc_reserve_space(inode, &data_reserved, > block_start, blocksize); > if (ret) > goto out; > > again: > page = find_or_create_page(mapping, index, mask); > if (!page) { > btrfs_delalloc_release_space(inode, data_reserved, > block_start, blocksize, true); > btrfs_delalloc_release_extents(BTRFS_I(inode), blocksize, true); > ret = -ENOMEM; > goto out; > } > > [CAUSE] > In above case, btrfs_delalloc_reserve_space() will call > btrfs_qgroup_reserve_data() and mark the io_tree range with > EXTENT_QGROUP_RESERVED flag. > > In the error handling path, we have the following call stack: > btrfs_delalloc_release_space() > |- btrfs_free_reserved_data_space() > |- btrsf_qgroup_free_data() > |- __btrfs_qgroup_release_data(reserved=@reserved, free=1) > |- qgroup_free_reserved_data(reserved=@reserved) > |- clear_record_extent_bits(); > |- freed += changeset.bytes_changed; > > However due to a completion bug, qgroup_free_reserved_data() will clear > EXTENT_QGROUP_RESERVED flag in BTRFS_I(inode)->io_failure_tree, other > than the correct BTRFS_I(inode)->io_tree. > Since io_failure_tree is never marked with that flag, > btrfs_qgroup_free_data() will not free any data reserved space at all, > causing a leakage. > > This type of error handling can only be triggered by errors outside of > qgroup code. So EDQUOT error from qgroup can't trigger it. > > [FIX] > Fix the wrong target io_tree. > > Reported-by: Josef Bacik <josef@toxicpanda.com> > Fixes: bc42bda22345 ("btrfs: qgroup: Fix qgroup reserved space underflow by only freeing reserved ranges") > Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: Nikolay Borisov <nborisov@suse.com> > --- > Changelog: > v2: > - Commit message polishment > Use proper call chain to describe the error, as it's pretty deep. > And rephrase how to trigger the bug. > --- > fs/btrfs/qgroup.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c > index 2891b57b9e1e..64bdc3e3652d 100644 > --- a/fs/btrfs/qgroup.c > +++ b/fs/btrfs/qgroup.c > @@ -3492,7 +3492,7 @@ static int qgroup_free_reserved_data(struct inode *inode, > * EXTENT_QGROUP_RESERVED, we won't double free. > * So not need to rush. > */ > - ret = clear_record_extent_bits(&BTRFS_I(inode)->io_failure_tree, > + ret = clear_record_extent_bits(&BTRFS_I(inode)->io_tree, > free_start, free_start + free_len - 1, > EXTENT_QGROUP_RESERVED, &changeset); > if (ret < 0) >
On Mon, Sep 16, 2019 at 08:02:38PM +0800, Qu Wenruo wrote: [...] 1 and 2 added to misc-next, thanks.
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c index 2891b57b9e1e..64bdc3e3652d 100644 --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -3492,7 +3492,7 @@ static int qgroup_free_reserved_data(struct inode *inode, * EXTENT_QGROUP_RESERVED, we won't double free. * So not need to rush. */ - ret = clear_record_extent_bits(&BTRFS_I(inode)->io_failure_tree, + ret = clear_record_extent_bits(&BTRFS_I(inode)->io_tree, free_start, free_start + free_len - 1, EXTENT_QGROUP_RESERVED, &changeset); if (ret < 0)
[BUG] Under the follow case with qgroup enabled, if some error happened after we have reserved delalloc space, then in error handling path, we could cause qgroup data space leakage: From btrfs_truncate_block() in inode.c: ret = btrfs_delalloc_reserve_space(inode, &data_reserved, block_start, blocksize); if (ret) goto out; again: page = find_or_create_page(mapping, index, mask); if (!page) { btrfs_delalloc_release_space(inode, data_reserved, block_start, blocksize, true); btrfs_delalloc_release_extents(BTRFS_I(inode), blocksize, true); ret = -ENOMEM; goto out; } [CAUSE] In above case, btrfs_delalloc_reserve_space() will call btrfs_qgroup_reserve_data() and mark the io_tree range with EXTENT_QGROUP_RESERVED flag. In the error handling path, we have the following call stack: btrfs_delalloc_release_space() |- btrfs_free_reserved_data_space() |- btrsf_qgroup_free_data() |- __btrfs_qgroup_release_data(reserved=@reserved, free=1) |- qgroup_free_reserved_data(reserved=@reserved) |- clear_record_extent_bits(); |- freed += changeset.bytes_changed; However due to a completion bug, qgroup_free_reserved_data() will clear EXTENT_QGROUP_RESERVED flag in BTRFS_I(inode)->io_failure_tree, other than the correct BTRFS_I(inode)->io_tree. Since io_failure_tree is never marked with that flag, btrfs_qgroup_free_data() will not free any data reserved space at all, causing a leakage. This type of error handling can only be triggered by errors outside of qgroup code. So EDQUOT error from qgroup can't trigger it. [FIX] Fix the wrong target io_tree. Reported-by: Josef Bacik <josef@toxicpanda.com> Fixes: bc42bda22345 ("btrfs: qgroup: Fix qgroup reserved space underflow by only freeing reserved ranges") Signed-off-by: Qu Wenruo <wqu@suse.com> --- Changelog: v2: - Commit message polishment Use proper call chain to describe the error, as it's pretty deep. And rephrase how to trigger the bug. --- fs/btrfs/qgroup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)