init: add support for root devices specified by partition UUID

[linux-flexiantxendom0-3.2.10.git] / init / do_mounts.c

diff --git a/init/do_mounts.c b/init/do_mounts.c
index a1de1bf..804f9c6 100644 (file)
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -12,6 +12,10 @@
 #include <linux/device.h>
 #include <linux/init.h>
 #include <linux/fs.h>
+#include <linux/initrd.h>
+#include <linux/async.h>
+#include <linux/fs_struct.h>
+#include <linux/slab.h>
 
 #include <linux/nfs_fs.h>
 #include <linux/nfs_fs_sb.h>
@@ -22,7 +26,7 @@
 int __initdata rd_doload;      /* 1 = load RAM disk, 0 = don't load */
 
 int root_mountflags = MS_RDONLY | MS_SILENT;
-char * __initdata root_device_name;
+static char * __initdata root_device_name;
 static char __initdata saved_root_name[64];
 static int __initdata root_wait;
 
@@ -54,6 +58,60 @@ static int __init readwrite(char *str)
 __setup("ro", readonly);
 __setup("rw", readwrite);
 
+/**
+ * match_dev_by_uuid - callback for finding a partition using its uuid
+ * @dev:       device passed in by the caller
+ * @data:      opaque pointer to a 36 byte char array with a UUID
+ *
+ * Returns 1 if the device matches, and 0 otherwise.
+ */
+static int __init match_dev_by_uuid(struct device *dev, void *data)
+{
+       u8 *uuid = data;
+       struct hd_struct *part = dev_to_part(dev);
+
+       if (!part->info)
+               goto no_match;
+
+       if (memcmp(uuid, part->info->uuid, sizeof(part->info->uuid)))
+                       goto no_match;
+
+       return 1;
+no_match:
+       return 0;
+}
+
+
+/**
+ * devt_from_partuuid - looks up the dev_t of a partition by its UUID
+ * @uuid:      36 byte char array containing a hex ascii UUID
+ *
+ * The function will return the first partition which contains a matching
+ * UUID value in its partition_meta_info struct.  This does not search
+ * by filesystem UUIDs.
+ *
+ * Returns the matching dev_t on success or 0 on failure.
+ */
+static dev_t __init devt_from_partuuid(char *uuid_str)
+{
+       dev_t res = 0;
+       struct device *dev = NULL;
+       u8 uuid[16];
+
+       /* Pack the requested UUID in the expected format. */
+       part_pack_uuid(uuid_str, uuid);
+
+       dev = class_find_device(&block_class, NULL, uuid, &match_dev_by_uuid);
+       if (!dev)
+               goto done;
+
+       res = dev->devt;
+       put_device(dev);
+
+done:
+       return res;
+}
+
 /*
  *     Convert a name into device number.  We accept the following variants:
  *
@@ -64,6 +122,8 @@ __setup("rw", readwrite);
  *         of partition - device number of disk plus the partition number
  *     5) /dev/<disk_name>p<decimal> - same as the above, that form is
  *        used when disk name of partitioned disk ends on a digit.
+ *     6) PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF representing the
+ *        unique id of a partition if the partition table provides it.
  *
  *     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
@@ -78,6 +138,16 @@ dev_t name_to_dev_t(char *name)
        dev_t res = 0;
        int part;
 
+       if (strncmp(name, "PARTUUID=", 9) == 0) {
+               name += 9;
+               if (strlen(name) != 36)
+                       goto fail;
+               res = devt_from_partuuid(name);
+               if (!res)
+                       goto fail;
+               goto done;
+       }
+
        if (strncmp(name, "/dev/", 5) != 0) {
                unsigned maj, min;
 
@@ -219,16 +289,17 @@ static int __init do_mount_root(char *name, char *fs, int flags, void *data)
 
        sys_chdir("/root");
        ROOT_DEV = current->fs->pwd.mnt->mnt_sb->s_dev;
-       printk("VFS: Mounted root (%s filesystem)%s.\n",
+       printk("VFS: Mounted root (%s filesystem)%s on device %u:%u.\n",
               current->fs->pwd.mnt->mnt_sb->s_type->name,
               current->fs->pwd.mnt->mnt_sb->s_flags & MS_RDONLY ?
-              " readonly" : "");
+              " readonly" : "", MAJOR(ROOT_DEV), MINOR(ROOT_DEV));
        return 0;
 }
 
 void __init mount_block_root(char *name, int flags)
 {
-       char *fs_names = __getname();
+       char *fs_names = __getname_gfp(GFP_KERNEL
+               | __GFP_NOTRACK_FALSE_POSITIVE);
        char *p;
 #ifdef CONFIG_BLOCK
        char b[BDEVNAME_SIZE];
@@ -262,6 +333,10 @@ retry:
                printk("Please append a correct \"root=\" boot option; here are the available partitions:\n");
 
                printk_all_partitions();
+#ifdef CONFIG_DEBUG_BLOCK_EXT_DEVT
+               printk("DEBUG_BLOCK_EXT_DEVT is enabled, you need to specify "
+                      "explicit textual name for \"root=\" boot option.\n");
+#endif
                panic("VFS: Unable to mount root fs on %s", b);
        }
 
@@ -364,9 +439,14 @@ void __init prepare_namespace(void)
                ssleep(root_delay);
        }
 
-       /* wait for the known devices to complete their probing */
-       while (driver_probe_done() != 0)
-               msleep(100);
+       /*
+        * wait for the known devices to complete their probing
+        *
+        * Note: this is a potential source of long boot delays.
+        * For example, it is not atypical to wait 5 seconds here
+        * for the touchpad of a laptop to initialize.
+        */
+       wait_for_device_probe();
 
        md_run_setup();
 
@@ -392,6 +472,7 @@ void __init prepare_namespace(void)
                while (driver_probe_done() != 0 ||
                        (ROOT_DEV = name_to_dev_t(saved_root_name)) == 0)
                        msleep(100);
+               async_synchronize_full();
        }
 
        is_floppy = MAJOR(ROOT_DEV) == FLOPPY_MAJOR;
@@ -401,7 +482,7 @@ void __init prepare_namespace(void)
 
        mount_root();
 out:
+       devtmpfs_mount("dev");
        sys_mount(".", "/", NULL, MS_MOVE, NULL);
        sys_chroot(".");
 }
-