From: Boris Burkov boris@bur.io
[ Upstream commit 70958a949d852cbecc3d46127bf0b24786df0130 ]
If you follow the seed/sprout wiki, it suggests the following workflow:
btrfstune -S 1 seed_dev mount seed_dev mnt btrfs device add sprout_dev mount -o remount,rw mnt
The first mount mounts the FS readonly, which results in not setting BTRFS_FS_OPEN, and setting the readonly bit on the sb. The device add somewhat surprisingly clears the readonly bit on the sb (though the mount is still practically readonly, from the users perspective...). Finally, the remount checks the readonly bit on the sb against the flag and sees no change, so it does not run the code intended to run on ro->rw transitions, leaving BTRFS_FS_OPEN unset.
As a result, when the cleaner_kthread runs, it sees no BTRFS_FS_OPEN and does no work. This results in leaking deleted snapshots until we run out of space.
I propose fixing it at the first departure from what feels reasonable: when we clear the readonly bit on the sb during device add.
A new fstest I have written reproduces the bug and confirms the fix.
Reviewed-by: Qu Wenruo wqu@suse.com Signed-off-by: Boris Burkov boris@bur.io Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/btrfs/volumes.c | 4 ---- 1 file changed, 4 deletions(-)
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index a06d530835d4e..28b79341e7e05 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -2840,8 +2840,6 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path set_blocksize(device->bdev_file, BTRFS_BDEV_BLOCKSIZE);
if (seeding_dev) { - btrfs_clear_sb_rdonly(sb); - /* GFP_KERNEL allocation must not be under device_list_mutex */ seed_devices = btrfs_init_sprout(fs_info); if (IS_ERR(seed_devices)) { @@ -2984,8 +2982,6 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path mutex_unlock(&fs_info->chunk_mutex); mutex_unlock(&fs_info->fs_devices->device_list_mutex); error_trans: - if (seeding_dev) - btrfs_set_sb_rdonly(sb); if (trans) btrfs_end_transaction(trans); error_free_zone: