From: Dennis Zhou <dennis@kernel.org>
To: David Sterba <dsterba@suse.com>, Chris Mason <clm@fb.com>,
Josef Bacik <josef@toxicpanda.com>,
Omar Sandoval <osandov@osandov.com>
Cc: kernel-team@fb.com, linux-btrfs@vger.kernel.org,
Dennis Zhou <dennis@kernel.org>
Subject: [PATCH 11/12] btrfs: ensure removal of discardable_* in free_bitmap()
Date: Thu, 2 Jan 2020 16:26:45 -0500 [thread overview]
Message-ID: <fe33c76ede300fd4cb03d0a7878cac0cbee47c42.1577999991.git.dennis@kernel.org> (raw)
In-Reply-To: <cover.1577999991.git.dennis@kernel.org>
In-Reply-To: <cover.1577999991.git.dennis@kernel.org>
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: Dennis Zhou <dennis@kernel.org>
---
fs/btrfs/free-space-cache.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 6d74d96a1d13..2b294c57060c 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -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 fully 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);
}
--
2.17.1
next prev parent reply other threads:[~2020-01-02 21:27 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-02 21:26 [PATCH 00/12] btrfs: async discard follow up Dennis Zhou
2020-01-02 21:26 ` [PATCH 01/12] btrfs: calculate discard delay based on number of extents Dennis Zhou
2020-01-03 14:38 ` David Sterba
2020-01-02 21:26 ` [PATCH 02/12] btrfs: add bps discard rate limit for async discard Dennis Zhou
2020-01-03 14:40 ` David Sterba
2020-01-02 21:26 ` [PATCH 03/12] btrfs: limit max discard size " Dennis Zhou
2020-01-03 14:41 ` David Sterba
2020-01-02 21:26 ` [PATCH 04/12] btrfs: make max async discard size tunable Dennis Zhou
2020-01-03 14:44 ` David Sterba
2020-01-02 21:26 ` [PATCH 05/12] btrfs: have multiple discard lists Dennis Zhou
2020-01-02 21:26 ` [PATCH 06/12] btrfs: only keep track of data extents for async discard Dennis Zhou
2020-01-02 21:26 ` [PATCH 07/12] btrfs: keep track of discard reuse stats Dennis Zhou
2020-01-02 21:26 ` [PATCH 08/12] btrfs: add async discard header Dennis Zhou
2020-01-02 21:26 ` [PATCH 09/12] btrfs: increase the metadata allowance for the free_space_cache Dennis Zhou
2020-01-02 21:26 ` [PATCH 10/12] btrfs: make smaller extents more likely to go into bitmaps Dennis Zhou
2020-01-02 21:26 ` Dennis Zhou [this message]
2020-01-02 21:26 ` [PATCH 12/12] btrfs: add correction to handle -1 edge case in async discard Dennis Zhou
2020-01-03 14:42 ` David Sterba
2020-01-05 20:35 ` Nikolay Borisov
2020-01-06 13:44 ` David Sterba
2020-01-03 14:51 ` [PATCH 00/12] btrfs: async discard follow up David Sterba
2020-01-03 17:43 ` Dennis Zhou
2020-01-06 15:25 ` David Sterba
2020-01-06 17:14 ` Dennis Zhou
2020-01-06 17:37 ` David Sterba
2020-01-06 16:30 ` David Sterba
2020-01-06 17:28 ` Dennis Zhou
2020-01-06 17:49 ` David Sterba
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