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authorDavid Sterba <dsterba@suse.com>2015-10-10 18:35:10 +0200
committerDavid Sterba <dsterba@suse.com>2015-10-10 18:35:10 +0200
commit33a9eca7e4a4c2c17aebbb11f0e506a48ebc30c9 (patch)
treed7651da94ff1ef4ad27ab0ac932665fd8ef7b41c
parentb666a9cd993c6a49c4bf23a1ed476359c978f60b (diff)
downloadlinux-33a9eca7e4a4c2c17aebbb11f0e506a48ebc30c9.tar.bz2
btrfs: comment waitqueue_active implied by locks
Suggested-by: Chris Mason <clm@fb.com> Signed-off-by: David Sterba <dsterba@suse.com>
-rw-r--r--fs/btrfs/raid56.c6
-rw-r--r--fs/btrfs/tree-log.c6
2 files changed, 11 insertions, 1 deletions
diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
index fcf7265ca46f..1a33d3eb36de 100644
--- a/fs/btrfs/raid56.c
+++ b/fs/btrfs/raid56.c
@@ -810,7 +810,11 @@ static noinline void unlock_stripe(struct btrfs_raid_bio *rbio)
}
goto done_nolock;
- } else if (waitqueue_active(&h->wait)) {
+ /*
+ * The barrier for this waitqueue_active is not needed,
+ * we're protected by h->lock and can't miss a wakeup.
+ */
+ } else if (waitqueue_active(&h->wait)) {
spin_unlock(&rbio->bio_list_lock);
spin_unlock_irqrestore(&h->lock, flags);
wake_up(&h->wait);
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 1bbaace73383..d0deb4643502 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -2950,6 +2950,9 @@ out_wake_log_root:
atomic_set(&log_root_tree->log_commit[index2], 0);
mutex_unlock(&log_root_tree->log_mutex);
+ /*
+ * The barrier before waitqueue_active is implied by mutex_unlock
+ */
if (waitqueue_active(&log_root_tree->log_commit_wait[index2]))
wake_up(&log_root_tree->log_commit_wait[index2]);
out:
@@ -2961,6 +2964,9 @@ out:
atomic_set(&root->log_commit[index1], 0);
mutex_unlock(&root->log_mutex);
+ /*
+ * The barrier before waitqueue_active is implied by mutex_unlock
+ */
if (waitqueue_active(&root->log_commit_wait[index1]))
wake_up(&root->log_commit_wait[index1]);
return ret;