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authorPaulo Alcantara (SUSE) <pc@cjr.nz>2019-10-01 14:10:27 -0300
committerDavid S. Miller <davem@davemloft.net>2019-10-02 12:15:15 -0400
commit8902dd526020748ccf16f753befc287b534fdefd (patch)
treec30a26e411b134f218d2b7c6e26a279033b44d2c /init
parent1f6d768a09c61e2454d4d67aee91210301c72211 (diff)
downloadlwn-8902dd526020748ccf16f753befc287b534fdefd.tar.gz
lwn-8902dd526020748ccf16f753befc287b534fdefd.zip
init: Support mounting root file systems over SMB
Add a new virtual device named /dev/cifs (0xfe) to tell the kernel to mount the root file system over the network by using SMB protocol. cifs_root_data() will be responsible to retrieve the parsed information of the new command-line option (cifsroot=) and then call do_mount_root() with the appropriate mount options for cifs.ko. Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'init')
-rw-r--r--init/do_mounts.c49
1 files changed, 49 insertions, 0 deletions
diff --git a/init/do_mounts.c b/init/do_mounts.c
index 9634ecf3743d..af9cda887a23 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -212,6 +212,7 @@ static int match_dev_by_label(struct device *dev, const void *data)
* 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
@@ -268,6 +269,9 @@ dev_t name_to_dev_t(const char *name)
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;
@@ -501,6 +505,42 @@ static int __init mount_nfs_root(void)
}
#endif
+#ifdef CONFIG_CIFS_ROOT
+
+extern int cifs_root_data(char **dev, char **opts);
+
+#define CIFSROOT_TIMEOUT_MIN 5
+#define CIFSROOT_TIMEOUT_MAX 30
+#define CIFSROOT_RETRY_MAX 5
+
+static int __init mount_cifs_root(void)
+{
+ char *root_dev, *root_data;
+ unsigned int timeout;
+ int try, err;
+
+ err = cifs_root_data(&root_dev, &root_data);
+ if (err != 0)
+ return 0;
+
+ timeout = CIFSROOT_TIMEOUT_MIN;
+ for (try = 1; ; try++) {
+ err = do_mount_root(root_dev, "cifs", root_mountflags,
+ root_data);
+ if (err == 0)
+ return 1;
+ if (try > CIFSROOT_RETRY_MAX)
+ break;
+
+ ssleep(timeout);
+ timeout <<= 1;
+ if (timeout > CIFSROOT_TIMEOUT_MAX)
+ timeout = CIFSROOT_TIMEOUT_MAX;
+ }
+ return 0;
+}
+#endif
+
#if defined(CONFIG_BLK_DEV_RAM) || defined(CONFIG_BLK_DEV_FD)
void __init change_floppy(char *fmt, ...)
{
@@ -542,6 +582,15 @@ void __init mount_root(void)
ROOT_DEV = Root_FD0;
}
#endif
+#ifdef CONFIG_CIFS_ROOT
+ if (ROOT_DEV == Root_CIFS) {
+ if (mount_cifs_root())
+ return;
+
+ printk(KERN_ERR "VFS: Unable to mount root fs via SMB, trying floppy.\n");
+ ROOT_DEV = Root_FD0;
+ }
+#endif
#ifdef CONFIG_BLK_DEV_FD
if (MAJOR(ROOT_DEV) == FLOPPY_MAJOR) {
/* rd_doload is 2 for a dual initrd/ramload setup */