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btrfs: remove extra barrier before waitqueue_active

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Removing barriers is scary, but a call to atomic_dec_and_test implies
a barrier, so we don't need to issue another one.

Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
David Sterba 2015-02-16 19:39:00 +01:00
parent a83342aa0c
commit 779adf0f64
1 changed files with 6 additions and 2 deletions
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8
fs/btrfs/tree-log.c
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@ -229,7 +229,9 @@ int btrfs_pin_log_trans(struct btrfs_root *root)
void btrfs_end_log_trans(struct btrfs_root *root)
{
if (atomic_dec_and_test(&root->log_writers)) {
smp_mb();
/*
* Implicit memory barrier after atomic_dec_and_test
*/
if (waitqueue_active(&root->log_writer_wait))
wake_up(&root->log_writer_wait);
}
@ -2820,7 +2822,9 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans,
mutex_lock(&log_root_tree->log_mutex);
if (atomic_dec_and_test(&log_root_tree->log_writers)) {
smp_mb();
/*
* Implicit memory barrier after atomic_dec_and_test
*/
if (waitqueue_active(&log_root_tree->log_writer_wait))
wake_up(&log_root_tree->log_writer_wait);
}