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Btrfs: fix qgroup double free after failure to reserve metadata for delalloc

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If we fail to reserve metadata for delalloc operations we end up releasing
the previously reserved qgroup amount twice, once explicitly under the
'out_qgroup' label by calling btrfs_qgroup_free_meta_prealloc() and once
again, under label 'out_fail', by calling btrfs_inode_rsv_release() with a
value of 'true' for its 'qgroup_free' argument, which results in
btrfs_qgroup_free_meta_prealloc() being called again, so we end up having
a double free.

Also if we fail to reserve the necessary qgroup amount, we jump to the
label 'out_fail', which calls btrfs_inode_rsv_release() and that in turns
calls btrfs_qgroup_free_meta_prealloc(), even though we weren't able to
reserve any qgroup amount. So we freed some amount we never reserved.

So fix this by removing the call to btrfs_inode_rsv_release() in the
failure path, since it's not necessary at all as we haven't changed the
inode's block reserve in any way at this point.

Fixes: c8eaeac7b7 ("btrfs: reserve delalloc metadata differently")
CC: stable@vger.kernel.org # 5.2+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Filipe Manana 2019-10-15 10:54:39 +01:00 committed by David Sterba
parent 1b2442b4ae
commit c7967fc149
1 changed files with 0 additions and 1 deletions
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fs/btrfs/delalloc-space.c
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@ -381,7 +381,6 @@ int btrfs_delalloc_reserve_metadata(struct btrfs_inode *inode, u64 num_bytes)
out_qgroup:
btrfs_qgroup_free_meta_prealloc(root, qgroup_reserve);
out_fail:
btrfs_inode_rsv_release(inode, true);
if (delalloc_lock)
mutex_unlock(&inode->delalloc_mutex);
return ret;