exofs: Add option to mount by osdname

If /dev/osd* devices are shuffled because more devices
where added, and/or login order has changed. It is hard to
mount the FS you want.

Add an option to mount by osdname. osdname is any osd-device's
osdname as specified to the mkfs.exofs command when formatting
the osd-devices.
The new mount format is:
	OPT="osdname=$UUID0,pid=$PID,_netdev"
	mount -t exofs -o $OPT $DEV_OSD0 $MOUNTDIR

if "osdname=" is specified in options above $DEV_OSD0 is
ignored and can be empty.

Also while at it: Removed some old unused Opt_* enums.

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>

2 files changed, 36 insertions, 5 deletions

diff --git a/Documentation/filesystems/exofs.txt b/Documentation/filesystems/exofs.txt
index abd2a9b5b787..23583a136975 100644
--- a/Documentation/filesystems/exofs.txt
+++ b/Documentation/filesystems/exofs.txt
@@ -104,7 +104,15 @@ Where:
     exofs specific options: Options are separated by commas (,)
                 pid=<integer> - The partition number to mount/create as
                                 container of the filesystem.
-                                This option is mandatory.
+                                This option is mandatory. integer can be
+                                Hex by pre-pending an 0x to the number.
+                osdname=<id>  - Mount by a device's osdname.
+                                osdname is usually a 36 character uuid of the
+                                form "d2683732-c906-4ee1-9dbd-c10c27bb40df".
+                                It is one of the device's uuid specified in the
+                                mkfs.exofs format command.
+                                If this option is specified then the /dev/osdX
+                                above can be empty and is ignored.
                 to=<integer>  - Timeout in ticks for a single command.
                                 default is (60 * HZ) [for debugging only]
 
diff --git a/fs/exofs/super.c b/fs/exofs/super.c
index e87510f4749e..474989eeb7d6 100644
--- a/fs/exofs/super.c
+++ b/fs/exofs/super.c
@@ -48,6 +48,7 @@
  * struct to hold what we get from mount options
  */
 struct exofs_mountopt {
+        bool is_osdname;
         const char *dev_name;
         uint64_t pid;
         int timeout;
@@ -56,7 +57,7 @@ struct exofs_mountopt {
 /*
  * exofs-specific mount-time options.
  */
-enum { Opt_pid, Opt_to, Opt_mkfs, Opt_format, Opt_err };
+enum { Opt_name, Opt_pid, Opt_to, Opt_err };
 
 /*
  * Our mount-time options.  These should ideally be 64-bit unsigned, but the
@@ -64,6 +65,7 @@ enum { Opt_pid, Opt_to, Opt_mkfs, Opt_format, Opt_err };
  * sufficient for most applications now.
  */
 static match_table_t tokens = {
+        {Opt_name, "osdname=%s"},
         {Opt_pid, "pid=%u"},
         {Opt_to, "to=%u"},
         {Opt_err, NULL}
@@ -94,6 +96,14 @@ static int parse_options(char *options, struct exofs_mountopt *opts)
 
                 token = match_token(p, tokens, args);
                 switch (token) {
+                case Opt_name:
+                        opts->dev_name = match_strdup(&args[0]);
+                        if (unlikely(!opts->dev_name)) {
+                                EXOFS_ERR("Error allocating dev_name");
+                                return -ENOMEM;
+                        }
+                        opts->is_osdname = true;
+                        break;
                 case Opt_pid:
                         if (0 == match_strlcpy(str, &args[0], sizeof(str)))
                                 return -EINVAL;
@@ -575,9 +585,17 @@ static int exofs_fill_super(struct super_block *sb, void *data, int silent)
                 goto free_bdi;
 
         /* use mount options to fill superblock */
-        od = osduld_path_lookup(opts->dev_name);
+        if (opts->is_osdname) {
+                struct osd_dev_info odi = {.systemid_len = 0};
+
+                odi.osdname_len = strlen(opts->dev_name);
+                odi.osdname = (u8 *)opts->dev_name;
+                od = osduld_info_lookup(&odi);
+        } else {
+                od = osduld_path_lookup(opts->dev_name);
+        }
         if (IS_ERR(od)) {
-                ret = PTR_ERR(od);
+                ret = -EINVAL;
                 goto free_sbi;
         }
 
@@ -670,6 +688,8 @@ static int exofs_fill_super(struct super_block *sb, void *data, int silent)
 
         _exofs_print_device("Mounting", opts->dev_name, sbi->layout.s_ods[0],
                             sbi->layout.s_pid);
+        if (opts->is_osdname)
+                kfree(opts->dev_name);
         return 0;
 
 free_sbi:
@@ -678,6 +698,8 @@ free_bdi:
         EXOFS_ERR("Unable to mount exofs on %s pid=0x%llx err=%d\n",
                   opts->dev_name, sbi->layout.s_pid, ret);
         exofs_free_sbi(sbi);
+        if (opts->is_osdname)
+                kfree(opts->dev_name);
         return ret;
 }
 
@@ -695,7 +717,8 @@ static struct dentry *exofs_mount(struct file_system_type *type,
         if (ret)
                 return ERR_PTR(ret);
 
-        opts.dev_name = dev_name;
+        if (!opts.dev_name)
+                opts.dev_name = dev_name;
         return mount_nodev(type, flags, &opts, exofs_fill_super);
 }