btrfs: wait part of the write_dev_flush() can be separated out

Submit and wait parts of write_dev_flush() can be split into two
separate functions for better readability.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 528eef9..2b00ebf 100644 (file)
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3488,37 +3488,16 @@ static void btrfs_end_empty_barrier(struct bio *bio)
 }
 
 /*
- * trigger flushes for one the devices.  If you pass wait == 0, the flushes are
- * sent down.  With wait == 1, it waits for the previous flush.
- *
- * any device where the flush fails with eopnotsupp are flagged as not-barrier
- * capable
+ * Submit a flush request to the device if it supports it. Error handling is
+ * done in the waiting counterpart.
  */
-static int write_dev_flush(struct btrfs_device *device, int wait)
+static void write_dev_flush(struct btrfs_device *device)
 {
        struct request_queue *q = bdev_get_queue(device->bdev);
        struct bio *bio;
-       int ret = 0;
 
        if (!test_bit(QUEUE_FLAG_WC, &q->queue_flags))
-               return 0;
-
-       if (wait) {
-               bio = device->flush_bio;
-               wait_for_completion(&device->flush_wait);
-
-               if (bio->bi_error) {
-                       ret = bio->bi_error;
-                       btrfs_dev_stat_inc_and_print(device,
-                               BTRFS_DEV_STAT_FLUSH_ERRS);
-               }
-
-               /* drop the reference from the wait == 0 run */
-               bio_put(bio);
-               device->flush_bio = NULL;
-
-               return ret;
-       }
+               return;
 
        /*
         * one reference for us, and we leave it for the
@@ -3535,8 +3514,32 @@ static int write_dev_flush(struct btrfs_device *device, int wait)
 
        bio_get(bio);
        btrfsic_submit_bio(bio);
+}
 
-       return 0;
+/*
+ * If the flush bio has been submitted by write_dev_flush, wait for it.
+ */
+static int wait_dev_flush(struct btrfs_device *device)
+{
+       int ret = 0;
+       struct bio *bio = device->flush_bio;
+
+       if (!bio)
+               return 0;
+
+       wait_for_completion(&device->flush_wait);
+
+       if (bio->bi_error) {
+               ret = bio->bi_error;
+               btrfs_dev_stat_inc_and_print(device,
+                               BTRFS_DEV_STAT_FLUSH_ERRS);
+       }
+
+       /* drop the reference from the wait == 0 run */
+       bio_put(bio);
+       device->flush_bio = NULL;
+
+       return ret;
 }
 
 static int check_barrier_error(struct btrfs_fs_devices *fsdevs)
@@ -3577,7 +3580,7 @@ static int barrier_all_devices(struct btrfs_fs_info *info)
                if (!dev->in_fs_metadata || !dev->writeable)
                        continue;
 
-               write_dev_flush(dev, 0);
+               write_dev_flush(dev);
                dev->last_flush_error = 0;
        }
 
@@ -3592,7 +3595,7 @@ static int barrier_all_devices(struct btrfs_fs_info *info)
                if (!dev->in_fs_metadata || !dev->writeable)
                        continue;
 
-               ret = write_dev_flush(dev, 1);
+               ret = wait_dev_flush(dev);
                if (ret) {
                        dev->last_flush_error = ret;
                        errors_wait++;