init: move the nfs/cifs/ram special cases out of name_to_dev_t

The nfs/cifs/ram special case only needs to be parsed once, and only in
the boot code.  Move them out of name_to_dev_t and into
prepare_namespace.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230531125535.676098-13-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 9e5bab29685ff0534fe82714dda5e20804c38ead..457c342d15977e0666f3a4db08ee24ba6ba38a89 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5452,7 +5452,12 @@
                        port and the regular usb controller gets disabled.
 
        root=           [KNL] Root filesystem
-                       See name_to_dev_t comment in init/do_mounts.c.
+                       Usually this a a block device specifier of some kind,
+                       see the name_to_dev_t comment in init/do_mounts.c for
+                       details.
+                       Alternatively this can be "ram" for the legacy initial
+                       ramdisk, "nfs" and "cifs" for root on a network file
+                       system, or "mtd" and "ubi" for mounting from raw flash.
 
        rootdelay=      [KNL] Delay (in seconds) to pause before attempting to
                        mount the root filesystem

diff --git a/init/do_mounts.c b/init/do_mounts.c
index d5c06c1546e82c76de21c858c91ba6bdb3be5339..86599faf2bf8a1906dbe2f521362344ab0c36ed3 100644 (file)
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -248,7 +248,6 @@ static dev_t devt_from_devnum(const char *name)
  *
  *     1) <hex_major><hex_minor> device number in hexadecimal represents itself
  *         no leading 0x, for example b302.
- *     2) /dev/nfs represents Root_NFS (0xff)
  *     3) /dev/<disk_name> represents the device number of disk
  *     4) /dev/<disk_name><decimal> represents the device number
  *         of partition - device number of disk plus the partition number
@@ -266,7 +265,6 @@ static dev_t devt_from_devnum(const char *name)
  *        a colon.
  *     9) PARTLABEL=<name> with name being the GPT partition label.
  *        MSDOS partitions do not support labels!
- *     10) /dev/cifs represents Root_CIFS (0xfe)
  *
  *     If name doesn't have fall into the categories above, we return (0,0).
  *     block_class is used to check if something is a disk name. If the disk
@@ -275,12 +273,6 @@ static dev_t devt_from_devnum(const char *name)
  */
 dev_t name_to_dev_t(const char *name)
 {
-       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)
                return devt_from_partuuid(name + 9);
@@ -631,6 +623,12 @@ static dev_t __init parse_root_device(char *root_device_name)
        if (!strncmp(root_device_name, "mtd", 3) ||
            !strncmp(root_device_name, "ubi", 3))
                return Root_Generic;
+       if (strcmp(root_device_name, "/dev/nfs") == 0)
+               return Root_NFS;
+       if (strcmp(root_device_name, "/dev/cifs") == 0)
+               return Root_CIFS;
+       if (strcmp(root_device_name, "/dev/ram") == 0)
+               return Root_RAM0;
        return name_to_dev_t(root_device_name);
 }