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Btrfs: barrier before waitqueue_active 

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>
This commit is contained in:
Josef Bacik 2012-08-01 15:36:24 -04:00 committed by Chris Mason
parent 1fa11e265f
commit 66657b318e
5 changed files with 10 additions and 12 deletions
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1
fs/btrfs/compression.c
View File

@ -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);
}

7
fs/btrfs/delayed-inode.c
View File

@ -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);
}
@ -1056,8 +1056,7 @@ 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);

7
fs/btrfs/disk-io.c
View File

@ -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);
@ -3783,14 +3781,17 @@ 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);

4
fs/btrfs/inode.c
View File

@ -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);

3
fs/btrfs/volumes.c
View File

@ -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);