btrfs: write_dev_flush does not return ENOMEM anymore

Since commit "btrfs: btrfs_io_bio_alloc never fails, skip error handling"
write_dev_flush will not return ENOMEM in the sending part. We do not
need to check for it in the callers.
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
[ updated changelog ]
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/disk-io.c

@@ -3505,13 +3505,6 @@ static int write_dev_flush(struct btrfs_device *device, int wait)
 
 	if (wait) {
 		bio = device->flush_bio;
-		if (!bio)
-			/*
-			 * This means the alloc has failed with ENOMEM, however
-			 * here we return 0, as its not a device error.
-			 */
-			return 0;
-
 		wait_for_completion(&device->flush_wait);
 
 		if (bio->bi_error) {
@@ -3548,25 +3541,16 @@ static int write_dev_flush(struct btrfs_device *device, int wait)
 
 static int check_barrier_error(struct btrfs_fs_devices *fsdevs)
 {
-	int submit_flush_error = 0;
 	int dev_flush_error = 0;
 	struct btrfs_device *dev;
-	int tolerance;
 
 	list_for_each_entry_rcu(dev, &fsdevs->devices, dev_list) {
-		if (!dev->bdev) {
-			submit_flush_error++;
-			dev_flush_error++;
-			continue;
-		}
-		if (dev->last_flush_error == -ENOMEM)
-			submit_flush_error++;
-		if (dev->last_flush_error && dev->last_flush_error != -ENOMEM)
+		if (!dev->bdev || dev->last_flush_error)
 			dev_flush_error++;
 	}
 
-	tolerance = fsdevs->fs_info->num_tolerated_disk_barrier_failures;
-	if (submit_flush_error > tolerance || dev_flush_error > tolerance)
+	if (dev_flush_error >
+	    fsdevs->fs_info->num_tolerated_disk_barrier_failures)
 		return -EIO;
 
 	return 0;
@@ -3596,10 +3580,8 @@ static int barrier_all_devices(struct btrfs_fs_info *info)
 		if (!dev->in_fs_metadata || !dev->writeable)
 			continue;
 
-		ret = write_dev_flush(dev, 0);
-		if (ret)
-			errors_send++;
-		dev->last_flush_error = ret;
+		write_dev_flush(dev, 0);
+		dev->last_flush_error = 0;
 	}
 
 	/* wait for all the barriers */
@@ -3620,16 +3602,6 @@ static int barrier_all_devices(struct btrfs_fs_info *info)
 		}
 	}
 
-	/*
-	 * Try hard in case of flush. Lets say, in RAID1 we have
-	 * the following situation
-	 *  dev1: EIO dev2: ENOMEM
-	 * this is not a fatal error as we hope to recover from
-	 * ENOMEM in the next attempt to flush.
-	 * But the following is considered as fatal
-	 *  dev1: ENOMEM dev2: ENOMEM
-	 *  dev1: bdev == NULL dev2: ENOMEM
-	 */
 	if (errors_send || errors_wait) {
 		/*
 		 * At some point we need the status of all disks