Commit 27f0afc7 authored by Dennis Zhou's avatar Dennis Zhou Committed by David Sterba
Browse files

btrfs: ensure removal of discardable_* in free_bitmap() 



Most callers of free_bitmap() only call it if bitmap_info->bytes is 0.
However, there are certain cases where we may free the free space cache
via __btrfs_remove_free_space_cache(). This exposes a path where
free_bitmap() is called regardless. This may result in a bad accounting
situation for discardable_bytes and discardable_extents. So, remove the
stats and call btrfs_discard_update_discardable().

Signed-off-by: default avatarDennis Zhou <dennis@kernel.org>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent f9bb615a

fs/btrfs/free-space-cache.c

+14 −0
Original line number Diff line number Diff line
@@ -1959,6 +1959,18 @@ static void add_new_bitmap(struct btrfs_free_space_ctl *ctl, 
static void free_bitmap(struct btrfs_free_space_ctl *ctl,

			struct btrfs_free_space *bitmap_info)

{

	/*

	 * Normally when this is called, the bitmap is completely empty. However,

	 * if we are blowing up the free space cache for one reason or another

	 * via __btrfs_remove_free_space_cache(), then it may not be freed and

	 * we may leave stats on the table.

	 */

	if (bitmap_info->bytes && !btrfs_free_space_trimmed(bitmap_info)) {

		ctl->discardable_extents[BTRFS_STAT_CURR] -=

			bitmap_info->bitmap_extents;

		ctl->discardable_bytes[BTRFS_STAT_CURR] -= bitmap_info->bytes;



	}

	unlink_free_space(ctl, bitmap_info);

	kmem_cache_free(btrfs_free_space_bitmap_cachep, bitmap_info->bitmap);

	kmem_cache_free(btrfs_free_space_cachep, bitmap_info);
@@ -2776,6 +2788,8 @@ void __btrfs_remove_free_space_cache(struct btrfs_free_space_ctl *ctl) 
{

	spin_lock(&ctl->tree_lock);

	__btrfs_remove_free_space_cache_locked(ctl);

	if (ctl->private)

		btrfs_discard_update_discardable(ctl->private, ctl);

	spin_unlock(&ctl->tree_lock);

}

CRA Git | Maintained and supported by SUSTech CRA and CCSE