Commit b18f3b60 authored by Naohiro Aota's avatar Naohiro Aota Committed by David Sterba
Browse files

btrfs: zoned: fix lock ordering in btrfs_zone_activate() 



The btrfs CI reported a lockdep warning as follows by running generic
generic/129.

   WARNING: possible circular locking dependency detected
   6.7.0-rc5+ #1 Not tainted
   ------------------------------------------------------
   kworker/u5:5/793427 is trying to acquire lock:
   ffff88813256d028 (&cache->lock){+.+.}-{2:2}, at: btrfs_zone_finish_one_bg+0x5e/0x130
   but task is already holding lock:
   ffff88810a23a318 (&fs_info->zone_active_bgs_lock){+.+.}-{2:2}, at: btrfs_zone_finish_one_bg+0x34/0x130
   which lock already depends on the new lock.

   the existing dependency chain (in reverse order) is:
   -> #1 (&fs_info->zone_active_bgs_lock){+.+.}-{2:2}:
   ...
   -> #0 (&cache->lock){+.+.}-{2:2}:
   ...

This is because we take fs_info->zone_active_bgs_lock after a block_group's
lock in btrfs_zone_activate() while doing the opposite in other places.

Fix the issue by expanding the fs_info->zone_active_bgs_lock's critical
section and taking it before a block_group's lock.

Fixes: a7e1ac7b ("btrfs: zoned: reserve zones for an active metadata/system block group")
CC: stable@vger.kernel.org # 6.6
Signed-off-by: default avatarNaohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent d967c914

fs/btrfs/zoned.c

+2 −6
Original line number Diff line number Diff line
@@ -2072,6 +2072,7 @@ bool btrfs_zone_activate(struct btrfs_block_group *block_group) 


	map = block_group->physical_map;



	spin_lock(&fs_info->zone_active_bgs_lock);

	spin_lock(&block_group->lock);

	if (test_bit(BLOCK_GROUP_FLAG_ZONE_IS_ACTIVE, &block_group->runtime_flags)) {

		ret = true;
@@ -2084,7 +2085,6 @@ bool btrfs_zone_activate(struct btrfs_block_group *block_group) 
		goto out_unlock;

	}



	spin_lock(&fs_info->zone_active_bgs_lock);

	for (i = 0; i < map->num_stripes; i++) {

		struct btrfs_zoned_device_info *zinfo;

		int reserved = 0;
@@ -2104,20 +2104,17 @@ bool btrfs_zone_activate(struct btrfs_block_group *block_group) 
		 */

		if (atomic_read(&zinfo->active_zones_left) <= reserved) {

			ret = false;

			spin_unlock(&fs_info->zone_active_bgs_lock);

			goto out_unlock;

		}



		if (!btrfs_dev_set_active_zone(device, physical)) {

			/* Cannot activate the zone */

			ret = false;

			spin_unlock(&fs_info->zone_active_bgs_lock);

			goto out_unlock;

		}

		if (!is_data)

			zinfo->reserved_active_zones--;

	}

	spin_unlock(&fs_info->zone_active_bgs_lock);



	/* Successfully activated all the zones */

	set_bit(BLOCK_GROUP_FLAG_ZONE_IS_ACTIVE, &block_group->runtime_flags);
@@ -2125,8 +2122,6 @@ bool btrfs_zone_activate(struct btrfs_block_group *block_group) 


	/* For the active block group list */

	btrfs_get_block_group(block_group);



	spin_lock(&fs_info->zone_active_bgs_lock);

	list_add_tail(&block_group->active_bg_list, &fs_info->zone_active_bgs);

	spin_unlock(&fs_info->zone_active_bgs_lock);
@@ -2134,6 +2129,7 @@ bool btrfs_zone_activate(struct btrfs_block_group *block_group) 


out_unlock:

	spin_unlock(&block_group->lock);

	spin_unlock(&fs_info->zone_active_bgs_lock);

	return ret;

}