@@ -818,6 +818,7 @@ static void free_workspace(int type, struct list_head *workspace)
btrfs_compress_op[idx]->free_workspace(workspace);
atomic_dec(alloc_workspace);
wake:
+ smp_mb();
if (waitqueue_active(workspace_wait))
wake_up(workspace_wait);
}
@@ -512,8 +512,8 @@ static void __btrfs_remove_delayed_item(struct btrfs_delayed_item *delayed_item)
rb_erase(&delayed_item->rb_node, root);
delayed_item->delayed_node->count--;
- atomic_dec(&delayed_root->items);
- if (atomic_read(&delayed_root->items) < BTRFS_DELAYED_BACKGROUND &&
+ if (atomic_dec_return(&delayed_root->items) <
+ BTRFS_DELAYED_BACKGROUND &&
waitqueue_active(&delayed_root->wait))
wake_up(&delayed_root->wait);
}
@@ -1055,8 +1055,7 @@ static void btrfs_release_delayed_inode(struct btrfs_delayed_node *delayed_node)
delayed_node->count--;
delayed_root = delayed_node->root->fs_info->delayed_root;
- atomic_dec(&delayed_root->items);
- if (atomic_read(&delayed_root->items) <
+ if (atomic_dec_return(&delayed_root->items) <
BTRFS_DELAYED_BACKGROUND &&
waitqueue_active(&delayed_root->wait))
wake_up(&delayed_root->wait);
@@ -662,9 +662,12 @@ int btrfs_add_delayed_tree_ref(struct btrfs_fs_info *fs_info,
add_delayed_tree_ref(fs_info, trans, &ref->node, bytenr,
num_bytes, parent, ref_root, level, action,
for_cow);
- if (!need_ref_seq(for_cow, ref_root) &&
- waitqueue_active(&fs_info->tree_mod_seq_wait))
- wake_up(&fs_info->tree_mod_seq_wait);
+ if (!need_ref_seq(for_cow, ref_root)) {
+ smp_mb();
+ if (waitqueue_active(&fs_info->tree_mod_seq_wait))
+ wake_up(&fs_info->tree_mod_seq_wait);
+ }
+
spin_unlock(&delayed_refs->lock);
if (need_ref_seq(for_cow, ref_root))
btrfs_qgroup_record_ref(trans, &ref->node, extent_op);
@@ -713,9 +716,11 @@ int btrfs_add_delayed_data_ref(struct btrfs_fs_info *fs_info,
add_delayed_data_ref(fs_info, trans, &ref->node, bytenr,
num_bytes, parent, ref_root, owner, offset,
action, for_cow);
- if (!need_ref_seq(for_cow, ref_root) &&
- waitqueue_active(&fs_info->tree_mod_seq_wait))
- wake_up(&fs_info->tree_mod_seq_wait);
+ if (!need_ref_seq(for_cow, ref_root)) {
+ smp_mb();
+ if (waitqueue_active(&fs_info->tree_mod_seq_wait))
+ wake_up(&fs_info->tree_mod_seq_wait);
+ }
spin_unlock(&delayed_refs->lock);
if (need_ref_seq(for_cow, ref_root))
btrfs_qgroup_record_ref(trans, &ref->node, extent_op);
@@ -744,6 +749,7 @@ int btrfs_add_delayed_extent_op(struct btrfs_fs_info *fs_info,
num_bytes, BTRFS_UPDATE_DELAYED_HEAD,
extent_op->is_data);
+ smp_mb();
if (waitqueue_active(&fs_info->tree_mod_seq_wait))
wake_up(&fs_info->tree_mod_seq_wait);
spin_unlock(&delayed_refs->lock);
@@ -754,9 +754,7 @@ static void run_one_async_done(struct btrfs_work *work)
limit = btrfs_async_submit_limit(fs_info);
limit = limit * 2 / 3;
- atomic_dec(&fs_info->nr_async_submits);
-
- if (atomic_read(&fs_info->nr_async_submits) < limit &&
+ if (atomic_dec_return(&fs_info->nr_async_submits) < limit &&
waitqueue_active(&fs_info->async_submit_wait))
wake_up(&fs_info->async_submit_wait);
@@ -3785,14 +3783,17 @@ int btrfs_cleanup_transaction(struct btrfs_root *root)
/* FIXME: cleanup wait for commit */
t->in_commit = 1;
t->blocked = 1;
+ smp_mb();
if (waitqueue_active(&root->fs_info->transaction_blocked_wait))
wake_up(&root->fs_info->transaction_blocked_wait);
t->blocked = 0;
+ smp_mb();
if (waitqueue_active(&root->fs_info->transaction_wait))
wake_up(&root->fs_info->transaction_wait);
t->commit_done = 1;
+ smp_mb();
if (waitqueue_active(&t->commit_wait))
wake_up(&t->commit_wait);
@@ -1007,9 +1007,7 @@ static noinline void async_cow_submit(struct btrfs_work *work)
nr_pages = (async_cow->end - async_cow->start + PAGE_CACHE_SIZE) >>
PAGE_CACHE_SHIFT;
- atomic_sub(nr_pages, &root->fs_info->async_delalloc_pages);
-
- if (atomic_read(&root->fs_info->async_delalloc_pages) <
+ if (atomic_sub_return(nr_pages, &root->fs_info->async_delalloc_pages) <
5 * 1024 * 1024 &&
waitqueue_active(&root->fs_info->async_submit_wait))
wake_up(&root->fs_info->async_submit_wait);
@@ -227,9 +227,8 @@ loop_lock:
cur = pending;
pending = pending->bi_next;
cur->bi_next = NULL;
- atomic_dec(&fs_info->nr_async_bios);
- if (atomic_read(&fs_info->nr_async_bios) < limit &&
+ if (atomic_dec_return(&fs_info->nr_async_bios) < limit &&
waitqueue_active(&fs_info->async_submit_wait))
wake_up(&fs_info->async_submit_wait);
We need a barrir before calling waitqueue_active otherwise we will miss wakeups. So in places that do atomic_dec(); then atomic_read() use atomic_dec_return() which imply a memory barrier (see memory-barriers.txt) and then add an explicit memory barrier everywhere else that need them. Thanks, Signed-off-by: Josef Bacik <jbacik@fusionio.com> --- V1->V2: changed atomic_dec/atomic_read combos to atomic_dec_return() for the implied barrier. fs/btrfs/compression.c | 1 + fs/btrfs/delayed-inode.c | 7 +++---- fs/btrfs/delayed-ref.c | 18 ++++++++++++------ fs/btrfs/disk-io.c | 7 ++++--- fs/btrfs/inode.c | 4 +--- fs/btrfs/volumes.c | 3 +-- 6 files changed, 22 insertions(+), 18 deletions(-)