From: Naohiro Aota naohiro.aota@wdc.com
[ Upstream commit fa2068d7e922b434eba5bfb0131e6d39febfdb48 ]
The naming of space_info->active_total_bytes is misleading. It counts not only active block groups but also full ones which are previously active but now inactive. That confusion results in a bug not counting the full BGs into active_total_bytes on mount time.
For a background, there are three kinds of block groups in terms of activation.
1. Block groups never activated 2. Block groups currently active 3. Block groups previously active and currently inactive (due to fully written or zone finish)
What we really wanted to exclude from "total_bytes" is the total size of BGs #1. They seem empty and allocatable but since they are not activated, we cannot rely on them to do the space reservation.
And, since BGs #1 never get activated, they should have no "used", "reserved" and "pinned" bytes.
OTOH, BGs #3 can be counted in the "total", since they are already full we cannot allocate from them anyway. For them, "total_bytes == used + reserved + pinned + zone_unusable" should hold.
Tracking #2 and #3 as "active_total_bytes" (current implementation) is confusing. And, tracking #1 and subtract that properly from "total_bytes" every time you need space reservation is cumbersome.
Instead, we can count the whole region of a newly allocated block group as zone_unusable. Then, once that block group is activated, release [0 .. zone_capacity] from the zone_unusable counters. With this, we can eliminate the confusing ->active_total_bytes and the code will be common among regular and the zoned mode. Also, no additional counter is needed with this approach.
Fixes: 6a921de58992 ("btrfs: zoned: introduce space_info->active_total_bytes") CC: stable@vger.kernel.org # 6.1+ Signed-off-by: Naohiro Aota naohiro.aota@wdc.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/btrfs/free-space-cache.c | 8 +++++++- fs/btrfs/zoned.c | 24 +++++++++++++++++++----- 2 files changed, 26 insertions(+), 6 deletions(-)
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c index f4023651dd68b..6a8f2bd350f4b 100644 --- a/fs/btrfs/free-space-cache.c +++ b/fs/btrfs/free-space-cache.c @@ -2684,8 +2684,13 @@ static int __btrfs_add_free_space_zoned(struct btrfs_block_group *block_group, bg_reclaim_threshold = READ_ONCE(sinfo->bg_reclaim_threshold);
spin_lock(&ctl->tree_lock); + /* Count initial region as zone_unusable until it gets activated. */ if (!used) to_free = size; + else if (initial && + test_bit(BTRFS_FS_ACTIVE_ZONE_TRACKING, &block_group->fs_info->flags) && + (block_group->flags & (BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_SYSTEM))) + to_free = 0; else if (initial) to_free = block_group->zone_capacity; else if (offset >= block_group->alloc_offset) @@ -2713,7 +2718,8 @@ static int __btrfs_add_free_space_zoned(struct btrfs_block_group *block_group, reclaimable_unusable = block_group->zone_unusable - (block_group->length - block_group->zone_capacity); /* All the region is now unusable. Mark it as unused and reclaim */ - if (block_group->zone_unusable == block_group->length) { + if (block_group->zone_unusable == block_group->length && + block_group->alloc_offset) { btrfs_mark_bg_unused(block_group); } else if (bg_reclaim_threshold && reclaimable_unusable >= diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c index 0d88cc46ac5db..e97c5a1ac95d6 100644 --- a/fs/btrfs/zoned.c +++ b/fs/btrfs/zoned.c @@ -1575,9 +1575,19 @@ void btrfs_calc_zone_unusable(struct btrfs_block_group *cache) return;
WARN_ON(cache->bytes_super != 0); - unusable = (cache->alloc_offset - cache->used) + - (cache->length - cache->zone_capacity); - free = cache->zone_capacity - cache->alloc_offset; + + /* Check for block groups never get activated */ + if (test_bit(BTRFS_FS_ACTIVE_ZONE_TRACKING, &cache->fs_info->flags) && + cache->flags & (BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_SYSTEM) && + !test_bit(BLOCK_GROUP_FLAG_ZONE_IS_ACTIVE, &cache->runtime_flags) && + cache->alloc_offset == 0) { + unusable = cache->length; + free = 0; + } else { + unusable = (cache->alloc_offset - cache->used) + + (cache->length - cache->zone_capacity); + free = cache->zone_capacity - cache->alloc_offset; + }
/* We only need ->free_space in ALLOC_SEQ block groups */ cache->cached = BTRFS_CACHE_FINISHED; @@ -1914,7 +1924,11 @@ bool btrfs_zone_activate(struct btrfs_block_group *block_group)
/* Successfully activated all the zones */ set_bit(BLOCK_GROUP_FLAG_ZONE_IS_ACTIVE, &block_group->runtime_flags); - space_info->active_total_bytes += block_group->length; + WARN_ON(block_group->alloc_offset != 0); + if (block_group->zone_unusable == block_group->length) { + block_group->zone_unusable = block_group->length - block_group->zone_capacity; + space_info->bytes_zone_unusable -= block_group->zone_capacity; + } spin_unlock(&block_group->lock); btrfs_try_granting_tickets(fs_info, space_info); spin_unlock(&space_info->lock); @@ -2277,7 +2291,7 @@ int btrfs_zone_finish_one_bg(struct btrfs_fs_info *fs_info) u64 avail;
spin_lock(&block_group->lock); - if (block_group->reserved || + if (block_group->reserved || block_group->alloc_offset == 0 || (block_group->flags & BTRFS_BLOCK_GROUP_SYSTEM)) { spin_unlock(&block_group->lock); continue;