6.8-stable review patch. If anyone has any objections, please let me know.
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From: Qu Wenruo wqu@suse.com
[ Upstream commit d139ded8b9cdb897bb9539eb33311daf9a177fd2 ]
[BUG] If qgroup is marked inconsistent (e.g. caused by operations needing full subtree rescan, like creating a snapshot and assign to a higher level qgroup), btrfs would immediately start leaking its data reserved space.
The following script can easily reproduce it:
mkfs.btrfs -O quota -f $dev mount $dev $mnt btrfs subvolume create $mnt/subv1 btrfs qgroup create 1/0 $mnt
# This snapshot creation would mark qgroup inconsistent, # as the ownership involves different higher level qgroup, thus # we have to rescan both source and snapshot, which can be very # time consuming, thus here btrfs just choose to mark qgroup # inconsistent, and let users to determine when to do the rescan. btrfs subv snapshot -i 1/0 $mnt/subv1 $mnt/snap1
# Now this write would lead to qgroup rsv leak. xfs_io -f -c "pwrite 0 64k" $mnt/file1
# And at unmount time, btrfs would report 64K DATA rsv space leaked. umount $mnt
And we would have the following dmesg output for the unmount:
BTRFS info (device dm-1): last unmount of filesystem 14a3d84e-f47b-4f72-b053-a8a36eef74d3 BTRFS warning (device dm-1): qgroup 0/5 has unreleased space, type 0 rsv 65536
[CAUSE] Since commit e15e9f43c7ca ("btrfs: introduce BTRFS_QGROUP_RUNTIME_FLAG_NO_ACCOUNTING to skip qgroup accounting"), we introduce a mode for btrfs qgroup to skip the timing consuming backref walk, if the qgroup is already inconsistent.
But this skip also covered the data reserved freeing, thus the qgroup reserved space for each newly created data extent would not be freed, thus cause the leakage.
[FIX] Make the data extent reserved space freeing mandatory.
The qgroup reserved space handling is way cheaper compared to the backref walking part, and we always have the super sensitive leak detector, thus it's definitely worth to always free the qgroup reserved data space.
Reported-by: Fabian Vogt fvogt@suse.com Fixes: e15e9f43c7ca ("btrfs: introduce BTRFS_QGROUP_RUNTIME_FLAG_NO_ACCOUNTING to skip qgroup accounting") CC: stable@vger.kernel.org # 6.1+ Link: https://bugzilla.suse.com/show_bug.cgi?id=1216196 Reviewed-by: Filipe Manana fdmanana@suse.com Signed-off-by: Qu Wenruo wqu@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/btrfs/qgroup.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c index 5470e1cdf10c5..5df54f78db2b9 100644 --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -2959,11 +2959,6 @@ int btrfs_qgroup_account_extents(struct btrfs_trans_handle *trans) ctx.roots = NULL; }
- /* Free the reserved data space */ - btrfs_qgroup_free_refroot(fs_info, - record->data_rsv_refroot, - record->data_rsv, - BTRFS_QGROUP_RSV_DATA); /* * Use BTRFS_SEQ_LAST as time_seq to do special search, * which doesn't lock tree or delayed_refs and search @@ -2987,6 +2982,11 @@ int btrfs_qgroup_account_extents(struct btrfs_trans_handle *trans) record->old_roots = NULL; new_roots = NULL; } + /* Free the reserved data space */ + btrfs_qgroup_free_refroot(fs_info, + record->data_rsv_refroot, + record->data_rsv, + BTRFS_QGROUP_RSV_DATA); cleanup: ulist_free(record->old_roots); ulist_free(new_roots);