[PATCH 17/45] init: refactor name_to_dev_t

Christoph Hellwig
2020-11-28T22:12:03Z

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@lst.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Acked-by: Tejun Heo <tj@kernel.org>
---
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