[PATCH 1/1] ubi: Allow ubiblock devices nodes to be created by volume name instead of volume ID.

[Patrick Doyle <wpdster@gmail.com>]

Add support for CONFIG_MTD_UBI_BLOCK_BY_NAME, which enables ubi block
devices to be named by their volume name: /dev/ubiblock%d_%s rather than
their volume ID /dev/ubiblock%d_%d, so that one can mount e.g. a root
filesystem by UBI name instead of volume ID.  UBI volumes can be renamed
on-the-fly in user space. This allows the root file system to be swapped
from an "A" volume to a "B" volume without having to change the mount
options.

Signed-off-by: Patrick Doyle <pdoyle@irobot.com>
---
 drivers/mtd/ubi/Kconfig | 12 ++++++++++++
 drivers/mtd/ubi/block.c |  4 ++++
 2 files changed, 16 insertions(+)

diff --git a/drivers/mtd/ubi/Kconfig b/drivers/mtd/ubi/Kconfig
index 43d131f..d9320f0 100644
--- a/drivers/mtd/ubi/Kconfig
+++ b/drivers/mtd/ubi/Kconfig
@@ -103,4 +103,16 @@ config MTD_UBI_BLOCK

        If in doubt, say "N".

+config MTD_UBI_BLOCK_BY_NAME
+       bool "Create ubi block device nodes by name instead of volume ID"
+       default n
+       depends on MTD_UBI_BLOCK
+       help
+         This option enables ubi block devices to be named by their volume name
+     /dev/ubiblock%d_%s rather than their volume ID /dev/ubiblock%d_%d, so that
+     one can mount e.g. a root filesystem by UBI name instead of volume ID.
+     UBI volumes can be renamed on-the-fly in user space. This allows the root
+     file system to be swapped from an "A" volume to a "B" volume
without having to
+     change the mount options.
+
 endif # MTD_UBI
diff --git a/drivers/mtd/ubi/block.c b/drivers/mtd/ubi/block.c
index d0b63bbf..ac2d480 100644
--- a/drivers/mtd/ubi/block.c
+++ b/drivers/mtd/ubi/block.c
@@ -399,7 +399,11 @@ int ubiblock_create(struct ubi_volume_info *vi)
         goto out_put_disk;
     }
     gd->private_data = dev;
+#ifdef CONFIG_MTD_UBI_BLOCK_BY_NAME
+    sprintf(gd->disk_name, "ubiblock%d_%s", dev->ubi_num, vi->name);
+#else
     sprintf(gd->disk_name, "ubiblock%d_%d", dev->ubi_num, dev->vol_id);
+#endif
     set_capacity(gd, disk_capacity);
     dev->gd = gd;

-- 
2.7.4

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