btrfs: switch extent_buffer blocking_writers from atomic to int
The blocking_writers is either 0 or 1 and always updated under the lock,
so we don't need the atomic_t semantics.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c
index 2f6c3c7..5feb011 100644
--- a/fs/btrfs/locking.c
+++ b/fs/btrfs/locking.c
@@ -111,10 +111,10 @@ void btrfs_set_lock_blocking_write(struct extent_buffer *eb)
*/
if (eb->lock_nested && current->pid == eb->lock_owner)
return;
- if (atomic_read(&eb->blocking_writers) == 0) {
+ if (eb->blocking_writers == 0) {
btrfs_assert_spinning_writers_put(eb);
btrfs_assert_tree_locked(eb);
- atomic_inc(&eb->blocking_writers);
+ eb->blocking_writers++;
write_unlock(&eb->lock);
}
}
@@ -148,12 +148,11 @@ void btrfs_clear_lock_blocking_write(struct extent_buffer *eb)
*/
if (eb->lock_nested && current->pid == eb->lock_owner)
return;
- BUG_ON(atomic_read(&eb->blocking_writers) != 1);
write_lock(&eb->lock);
+ BUG_ON(eb->blocking_writers != 1);
btrfs_assert_spinning_writers_get(eb);
- /* atomic_dec_and_test implies a barrier */
- if (atomic_dec_and_test(&eb->blocking_writers))
- cond_wake_up_nomb(&eb->write_lock_wq);
+ if (--eb->blocking_writers == 0)
+ cond_wake_up(&eb->write_lock_wq);
}
/*
@@ -167,12 +166,10 @@ void btrfs_tree_read_lock(struct extent_buffer *eb)
if (trace_btrfs_tree_read_lock_enabled())
start_ns = ktime_get_ns();
again:
- BUG_ON(!atomic_read(&eb->blocking_writers) &&
- current->pid == eb->lock_owner);
-
read_lock(&eb->lock);
- if (atomic_read(&eb->blocking_writers) &&
- current->pid == eb->lock_owner) {
+ BUG_ON(eb->blocking_writers == 0 &&
+ current->pid == eb->lock_owner);
+ if (eb->blocking_writers && current->pid == eb->lock_owner) {
/*
* This extent is already write-locked by our thread. We allow
* an additional read lock to be added because it's for the same
@@ -185,10 +182,10 @@ void btrfs_tree_read_lock(struct extent_buffer *eb)
trace_btrfs_tree_read_lock(eb, start_ns);
return;
}
- if (atomic_read(&eb->blocking_writers)) {
+ if (eb->blocking_writers) {
read_unlock(&eb->lock);
wait_event(eb->write_lock_wq,
- atomic_read(&eb->blocking_writers) == 0);
+ eb->blocking_writers == 0);
goto again;
}
btrfs_assert_tree_read_locks_get(eb);
@@ -203,11 +200,11 @@ void btrfs_tree_read_lock(struct extent_buffer *eb)
*/
int btrfs_tree_read_lock_atomic(struct extent_buffer *eb)
{
- if (atomic_read(&eb->blocking_writers))
+ if (eb->blocking_writers)
return 0;
read_lock(&eb->lock);
- if (atomic_read(&eb->blocking_writers)) {
+ if (eb->blocking_writers) {
read_unlock(&eb->lock);
return 0;
}
@@ -223,13 +220,13 @@ int btrfs_tree_read_lock_atomic(struct extent_buffer *eb)
*/
int btrfs_try_tree_read_lock(struct extent_buffer *eb)
{
- if (atomic_read(&eb->blocking_writers))
+ if (eb->blocking_writers)
return 0;
if (!read_trylock(&eb->lock))
return 0;
- if (atomic_read(&eb->blocking_writers)) {
+ if (eb->blocking_writers) {
read_unlock(&eb->lock);
return 0;
}
@@ -245,13 +242,11 @@ int btrfs_try_tree_read_lock(struct extent_buffer *eb)
*/
int btrfs_try_tree_write_lock(struct extent_buffer *eb)
{
- if (atomic_read(&eb->blocking_writers) ||
- atomic_read(&eb->blocking_readers))
+ if (eb->blocking_writers || atomic_read(&eb->blocking_readers))
return 0;
write_lock(&eb->lock);
- if (atomic_read(&eb->blocking_writers) ||
- atomic_read(&eb->blocking_readers)) {
+ if (eb->blocking_writers || atomic_read(&eb->blocking_readers)) {
write_unlock(&eb->lock);
return 0;
}
@@ -322,10 +317,9 @@ void btrfs_tree_lock(struct extent_buffer *eb)
WARN_ON(eb->lock_owner == current->pid);
again:
wait_event(eb->read_lock_wq, atomic_read(&eb->blocking_readers) == 0);
- wait_event(eb->write_lock_wq, atomic_read(&eb->blocking_writers) == 0);
+ wait_event(eb->write_lock_wq, eb->blocking_writers == 0);
write_lock(&eb->lock);
- if (atomic_read(&eb->blocking_readers) ||
- atomic_read(&eb->blocking_writers)) {
+ if (atomic_read(&eb->blocking_readers) || eb->blocking_writers) {
write_unlock(&eb->lock);
goto again;
}
@@ -340,7 +334,7 @@ void btrfs_tree_lock(struct extent_buffer *eb)
*/
void btrfs_tree_unlock(struct extent_buffer *eb)
{
- int blockers = atomic_read(&eb->blocking_writers);
+ int blockers = eb->blocking_writers;
BUG_ON(blockers > 1);
@@ -351,7 +345,7 @@ void btrfs_tree_unlock(struct extent_buffer *eb)
if (blockers) {
btrfs_assert_no_spinning_writers(eb);
- atomic_dec(&eb->blocking_writers);
+ eb->blocking_writers--;
/* Use the lighter barrier after atomic */
smp_mb__after_atomic();
cond_wake_up_nomb(&eb->write_lock_wq);