btrfs: scrub: convert scrub_workers_refcnt to refcount_t

asj · kdave · commit ff09c4ca5992 · 2019-02-25T14:13:38.000+01:00
Use the refcount_t for fs_info::scrub_workers_refcnt instead of int so
we get the extra checks. All reference changes are still done under
scrub_lock.

Signed-off-by: Anand Jain &lt;anand.jain@oracle.com&gt;
Reviewed-by: David Sterba &lt;dsterba@suse.com&gt;
Signed-off-by: David Sterba &lt;dsterba@suse.com&gt;
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
@@ -1075,7 +1075,7 @@ struct btrfs_fs_info {
 	atomic_t scrubs_paused;
 	atomic_t scrub_cancel_req;
 	wait_queue_head_t scrub_pause_wait;
-	int scrub_workers_refcnt;
+	refcount_t scrub_workers_refcnt;
 	struct btrfs_workqueue *scrub_workers;
 	struct btrfs_workqueue *scrub_wr_completion_workers;
 	struct btrfs_workqueue *scrub_nocow_workers;
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
@@ -2109,7 +2109,7 @@ static void btrfs_init_scrub(struct btrfs_fs_info *fs_info)
 	atomic_set(&fs_info->scrubs_paused, 0);
 	atomic_set(&fs_info->scrub_cancel_req, 0);
 	init_waitqueue_head(&fs_info->scrub_pause_wait);
-	fs_info->scrub_workers_refcnt = 0;
+	refcount_set(&fs_info->scrub_workers_refcnt, 0);
 }
 
 static void btrfs_init_balance(struct btrfs_fs_info *fs_info)
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
@@ -3743,7 +3743,7 @@ static noinline_for_stack int scrub_workers_get(struct btrfs_fs_info *fs_info,
 
 	lockdep_assert_held(&fs_info->scrub_lock);
 
-	if (fs_info->scrub_workers_refcnt == 0) {
+	if (refcount_read(&fs_info->scrub_workers_refcnt) == 0) {
 		fs_info->scrub_workers = btrfs_alloc_workqueue(fs_info, "scrub",
 				flags, is_dev_replace ? 1 : max_active, 4);
 		if (!fs_info->scrub_workers)
@@ -3760,8 +3760,11 @@ static noinline_for_stack int scrub_workers_get(struct btrfs_fs_info *fs_info,
 					      max_active, 2);
 		if (!fs_info->scrub_parity_workers)
 			goto fail_scrub_parity_workers;
+
+		refcount_set(&fs_info->scrub_workers_refcnt, 1);
+	} else {
+		refcount_inc(&fs_info->scrub_workers_refcnt);
 	}
-	++fs_info->scrub_workers_refcnt;
 	return 0;
 
 fail_scrub_parity_workers:
@@ -3927,7 +3930,7 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start,
 
 	mutex_lock(&fs_info->scrub_lock);
 	dev->scrub_ctx = NULL;
-	if (--fs_info->scrub_workers_refcnt == 0) {
+	if (refcount_dec_and_test(&fs_info->scrub_workers_refcnt)) {
 		scrub_workers = fs_info->scrub_workers;
 		scrub_wr_comp = fs_info->scrub_wr_completion_workers;
 		scrub_parity = fs_info->scrub_parity_workers;

Original file line number	Diff line number	Diff line change
`@@ -2109,7 +2109,7 @@ static void btrfs_init_scrub(struct btrfs_fs_info *fs_info)`
`2109`	`2109`	`atomic_set(&fs_info->scrubs_paused, 0);`
`2110`	`2110`	`atomic_set(&fs_info->scrub_cancel_req, 0);`
`2111`	`2111`	`init_waitqueue_head(&fs_info->scrub_pause_wait);`
`2112`		`- fs_info->scrub_workers_refcnt = 0;`
	`2112`	`+ refcount_set(&fs_info->scrub_workers_refcnt, 0);`
`2113`	`2113`	`}`
`2114`	`2114`
`2115`	`2115`	`static void btrfs_init_balance(struct btrfs_fs_info *fs_info)`