[PATCH 17/45] init: refactor name_to_dev_t

[Christoph Hellwig <hch@xxxxxx>]

Split each case into a self-contained helper, and move the block
dependent code entirely under the pre-existing #ifdef CONFIG_BLOCK.
This allows to remove the blk_lookup_devt stub in genhd.h.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@xxxxxxx>
---
 include/linux/genhd.h |   7 +-
 init/do_mounts.c      | 183 +++++++++++++++++++++---------------------
 2 files changed, 91 insertions(+), 99 deletions(-)

diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 22f5b9fd96f8bf..ca5e356084c353 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -388,18 +388,13 @@ static inline void bd_unlink_disk_holder(struct 
block_device *bdev,
 }
 #endif /* CONFIG_SYSFS */
 
+dev_t blk_lookup_devt(const char *name, int partno);
 #ifdef CONFIG_BLOCK
 void printk_all_partitions(void);
-dev_t blk_lookup_devt(const char *name, int partno);
 #else /* CONFIG_BLOCK */
 static inline void printk_all_partitions(void)
 {
 }
-static inline dev_t blk_lookup_devt(const char *name, int partno)
-{
-       dev_t devt = MKDEV(0, 0);
-       return devt;
-}
 #endif /* CONFIG_BLOCK */
 
 #endif /* _LINUX_GENHD_H */
diff --git a/init/do_mounts.c b/init/do_mounts.c
index b5f9604d0c98a2..aef2f24461c7f1 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -90,7 +90,6 @@ static int match_dev_by_uuid(struct device *dev, const void 
*data)
        return 0;
 }
 
-
 /**
  * devt_from_partuuid - looks up the dev_t of a partition by its UUID
  * @uuid_str:  char array containing ascii UUID
@@ -186,7 +185,83 @@ static int match_dev_by_label(struct device *dev, const 
void *data)
 
        return 0;
 }
-#endif
+
+static dev_t devt_from_partlabel(const char *label)
+{
+       struct device *dev;
+       dev_t devt = 0;
+
+       dev = class_find_device(&block_class, NULL, label, &match_dev_by_label);
+       if (dev) {
+               devt = dev->devt;
+               put_device(dev);
+       }
+
+       return devt;
+}
+
+static dev_t devt_from_devname(const char *name)
+{
+       dev_t devt = 0;
+       int part;
+       char s[32];
+       char *p;
+
+       if (strlen(name) > 31)
+               return 0;
+       strcpy(s, name);
+       for (p = s; *p; p++) {
+               if (*p == '/')
+                       *p = '!';
+       }
+
+       devt = blk_lookup_devt(s, 0);
+       if (devt)
+               return devt;
+
+       /*
+        * Try non-existent, but valid partition, which may only exist after
+        * opening the device, like partitioned md devices.
+        */
+       while (p > s && isdigit(p[-1]))
+               p--;
+       if (p == s || !*p || *p == '0')
+               return 0;
+
+       /* try disk name without <part number> */
+       part = simple_strtoul(p, NULL, 10);
+       *p = '\0';
+       devt = blk_lookup_devt(s, part);
+       if (devt)
+               return devt;
+
+       /* try disk name without p<part number> */
+       if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
+               return 0;
+       p[-1] = '\0';
+       return blk_lookup_devt(s, part);
+}
+#endif /* CONFIG_BLOCK */
+
+static dev_t devt_from_devnum(const char *name)
+{
+       unsigned maj, min, offset;
+       dev_t devt = 0;
+       char *p, dummy;
+
+       if (sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2 ||
+           sscanf(name, "%u:%u:%u:%c", &maj, &min, &offset, &dummy) == 3) {
+               devt = MKDEV(maj, min);
+               if (maj != MAJOR(devt) || min != MINOR(devt))
+                       return 0;
+       } else {
+               devt = new_decode_dev(simple_strtoul(name, &p, 16));
+               if (*p)
+                       return 0;
+       }
+
+       return devt;
+}
 
 /*
  *     Convert a name into device number.  We accept the following variants:
@@ -218,101 +293,23 @@ static int match_dev_by_label(struct device *dev, const 
void *data)
  *     name contains slashes, the device name has them replaced with
  *     bangs.
  */
-
 dev_t name_to_dev_t(const char *name)
 {
-       char s[32];
-       char *p;
-       dev_t res = 0;
-       int part;
-
+       if (strcmp(name, "/dev/nfs") == 0)
+               return Root_NFS;
+       if (strcmp(name, "/dev/cifs") == 0)
+               return Root_CIFS;
+       if (strcmp(name, "/dev/ram") == 0)
+               return Root_RAM0;
 #ifdef CONFIG_BLOCK
-       if (strncmp(name, "PARTUUID=", 9) == 0) {
-               name += 9;
-               res = devt_from_partuuid(name);
-               if (!res)
-                       goto fail;
-               goto done;
-       } else if (strncmp(name, "PARTLABEL=", 10) == 0) {
-               struct device *dev;
-
-               dev = class_find_device(&block_class, NULL, name + 10,
-                                       &match_dev_by_label);
-               if (!dev)
-                       goto fail;
-
-               res = dev->devt;
-               put_device(dev);
-               goto done;
-       }
+       if (strncmp(name, "PARTUUID=", 9) == 0)
+               return devt_from_partuuid(name + 9);
+       if (strncmp(name, "PARTLABEL=", 10) == 0)
+               return devt_from_partlabel(name + 10);
+       if (strncmp(name, "/dev/", 5) == 0)
+               return devt_from_devname(name + 5);
 #endif
-
-       if (strncmp(name, "/dev/", 5) != 0) {
-               unsigned maj, min, offset;
-               char dummy;
-
-               if ((sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2) ||
-                   (sscanf(name, "%u:%u:%u:%c", &maj, &min, &offset, &dummy) 
== 3)) {
-                       res = MKDEV(maj, min);
-                       if (maj != MAJOR(res) || min != MINOR(res))
-                               goto fail;
-               } else {
-                       res = new_decode_dev(simple_strtoul(name, &p, 16));
-                       if (*p)
-                               goto fail;
-               }
-               goto done;
-       }
-
-       name += 5;
-       res = Root_NFS;
-       if (strcmp(name, "nfs") == 0)
-               goto done;
-       res = Root_CIFS;
-       if (strcmp(name, "cifs") == 0)
-               goto done;
-       res = Root_RAM0;
-       if (strcmp(name, "ram") == 0)
-               goto done;
-
-       if (strlen(name) > 31)
-               goto fail;
-       strcpy(s, name);
-       for (p = s; *p; p++)
-               if (*p == '/')
-                       *p = '!';
-       res = blk_lookup_devt(s, 0);
-       if (res)
-               goto done;
-
-       /*
-        * try non-existent, but valid partition, which may only exist
-        * after revalidating the disk, like partitioned md devices
-        */
-       while (p > s && isdigit(p[-1]))
-               p--;
-       if (p == s || !*p || *p == '0')
-               goto fail;
-
-       /* try disk name without <part number> */
-       part = simple_strtoul(p, NULL, 10);
-       *p = '\0';
-       res = blk_lookup_devt(s, part);
-       if (res)
-               goto done;
-
-       /* try disk name without p<part number> */
-       if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
-               goto fail;
-       p[-1] = '\0';
-       res = blk_lookup_devt(s, part);
-       if (res)
-               goto done;
-
-fail:
-       return 0;
-done:
-       return res;
+       return devt_from_devnum(name);
 }
 EXPORT_SYMBOL_GPL(name_to_dev_t);
 
-- 
2.29.2