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btrfs: zoned: fix lock ordering in btrfs_zone_activate()

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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: a7e1ac7bdc ("btrfs: zoned: reserve zones for an active metadata/system block group")
CC: stable@vger.kernel.org # 6.6
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Naohiro Aota
2023-12-22 13:56:34 +09:00
committed by David Sterba
parent d967c914a6
commit b18f3b60b3
1 changed files with 2 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
fs/btrfs/zoned.c
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@@ -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;
}