nfs/blocklayout: refactor open-by-wwn

The current code works with the standard udev/systemd names, but we'll have
to add another method in the next patch.  Refactor it into a separate helper
to make room for the new variant.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

diff --git a/fs/nfs/blocklayout/dev.c b/fs/nfs/blocklayout/dev.c
index 7fb9c07c078c018fdaea643c4c018c824cdfb7e4..ea70883a174a53a102d336ff1ccf24d023765360 100644 (file)
--- a/fs/nfs/blocklayout/dev.c
+++ b/fs/nfs/blocklayout/dev.c
@@ -287,44 +287,45 @@ bl_validate_designator(struct pnfs_block_volume *v)
        }
 }
 
+/*
+ * Try to open the udev path for the WWN.  At least on Debian the udev
+ * by-id path will always point to the dm-multipath device if one exists.
+ */
+static struct block_device *
+bl_open_udev_path(struct pnfs_block_volume *v)
+{
+       struct block_device *bdev;
+       const char *devname;
+
+       devname = kasprintf(GFP_KERNEL, "/dev/disk/by-id/wwn-0x%*phN",
+                               v->scsi.designator_len, v->scsi.designator);
+       if (!devname)
+               return ERR_PTR(-ENOMEM);
+
+       bdev = blkdev_get_by_path(devname, FMODE_READ | FMODE_WRITE, NULL);
+       if (IS_ERR(bdev)) {
+               pr_warn("pNFS: failed to open device %s (%ld)\n",
+                       devname, PTR_ERR(bdev));
+       }
+
+       kfree(devname);
+       return bdev;
+}
+
 static int
 bl_parse_scsi(struct nfs_server *server, struct pnfs_block_dev *d,
                struct pnfs_block_volume *volumes, int idx, gfp_t gfp_mask)
 {
        struct pnfs_block_volume *v = &volumes[idx];
        const struct pr_ops *ops;
-       const char *devname;
        int error;
 
        if (!bl_validate_designator(v))
                return -EINVAL;
 
-       switch (v->scsi.designator_len) {
-       case 8:
-               devname = kasprintf(GFP_KERNEL, "/dev/disk/by-id/wwn-0x%8phN",
-                               v->scsi.designator);
-               break;
-       case 12:
-               devname = kasprintf(GFP_KERNEL, "/dev/disk/by-id/wwn-0x%12phN",
-                               v->scsi.designator);
-               break;
-       case 16:
-               devname = kasprintf(GFP_KERNEL, "/dev/disk/by-id/wwn-0x%16phN",
-                               v->scsi.designator);
-               break;
-       default:
-               return -EINVAL;
-       }
-
-       d->bdev = blkdev_get_by_path(devname, FMODE_READ | FMODE_WRITE, NULL);
-       if (IS_ERR(d->bdev)) {
-               pr_warn("pNFS: failed to open device %s (%ld)\n",
-                       devname, PTR_ERR(d->bdev));
-               kfree(devname);
+       d->bdev = bl_open_udev_path(v);
+       if (IS_ERR(d->bdev))
                return PTR_ERR(d->bdev);
-       }
-
-       kfree(devname);
 
        d->len = i_size_read(d->bdev->bd_inode);
        d->map = bl_map_simple;