From e24d12b7442afa9d41331a951fca467449ff1488 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 14 Jul 2021 16:23:19 -0400 Subject: init: split get_fs_names Split get_fs_names into one function that splits up the command line argument, and one that gets the list of all registered file systems. Signed-off-by: Christoph Hellwig Signed-off-by: Al Viro --- init/do_mounts.c | 48 ++++++++++++++++++++++++++---------------------- 1 file changed, 26 insertions(+), 22 deletions(-) (limited to 'init') diff --git a/init/do_mounts.c b/init/do_mounts.c index 74aede860de7..ec32de3ad52b 100644 --- a/init/do_mounts.c +++ b/init/do_mounts.c @@ -338,30 +338,31 @@ __setup("rootflags=", root_data_setup); __setup("rootfstype=", fs_names_setup); __setup("rootdelay=", root_delay_setup); -static void __init get_fs_names(char *page) +static void __init split_fs_names(char *page, char *names) { - char *s = page; - - if (root_fs_names) { - strcpy(page, root_fs_names); - while (*s++) { - if (s[-1] == ',') - s[-1] = '\0'; - } - } else { - int len = get_filesystem_list(page); - char *p, *next; + strcpy(page, root_fs_names); + while (*page++) { + if (page[-1] == ',') + page[-1] = '\0'; + } + *page = '\0'; +} - page[len] = '\0'; - for (p = page-1; p; p = next) { - next = strchr(++p, '\n'); - if (*p++ != '\t') - continue; - while ((*s++ = *p++) != '\n') - ; - s[-1] = '\0'; - } +static void __init get_all_fs_names(char *page) +{ + int len = get_filesystem_list(page); + char *s = page, *p, *next; + + page[len] = '\0'; + for (p = page - 1; p; p = next) { + next = strchr(++p, '\n'); + if (*p++ != '\t') + continue; + while ((*s++ = *p++) != '\n') + ; + s[-1] = '\0'; } + *s = '\0'; } @@ -411,7 +412,10 @@ void __init mount_block_root(char *name, int flags) scnprintf(b, BDEVNAME_SIZE, "unknown-block(%u,%u)", MAJOR(ROOT_DEV), MINOR(ROOT_DEV)); - get_fs_names(fs_names); + if (root_fs_names) + split_fs_names(fs_names, root_fs_names); + else + get_all_fs_names(fs_names); retry: for (p = fs_names; *p; p += strlen(p)+1) { int err = do_mount_root(name, p, flags, root_mount_data); -- cgit v1.2.3-70-g09d2 From f9259be6a9e7c22d92e5a5000913147ae17e8321 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 14 Jul 2021 16:23:20 -0400 Subject: init: allow mounting arbitrary non-blockdevice filesystems as root Currently the only non-blockdevice filesystems that can be used as the initial root filesystem are NFS and CIFS, which use the magic "root=/dev/nfs" and "root=/dev/cifs" syntax that requires the root device file system details to come from filesystem specific kernel command line options. Add a little bit of new code that allows to just pass arbitrary string mount options to any non-blockdevice filesystems so that it can be mounted as the root file system. For example a virtiofs root file system can be mounted using the following syntax: "root=myfs rootfstype=virtiofs rw" Based on an earlier patch from Vivek Goyal . Signed-off-by: Christoph Hellwig Signed-off-by: Al Viro --- init/do_mounts.c | 43 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) (limited to 'init') diff --git a/init/do_mounts.c b/init/do_mounts.c index ec32de3ad52b..bdeb90b8d669 100644 --- a/init/do_mounts.c +++ b/init/do_mounts.c @@ -534,6 +534,45 @@ static int __init mount_cifs_root(void) } #endif +static bool __init fs_is_nodev(char *fstype) +{ + struct file_system_type *fs = get_fs_type(fstype); + bool ret = false; + + if (fs) { + ret = !(fs->fs_flags & FS_REQUIRES_DEV); + put_filesystem(fs); + } + + return ret; +} + +static int __init mount_nodev_root(void) +{ + char *fs_names, *fstype; + int err = -EINVAL; + + fs_names = (void *)__get_free_page(GFP_KERNEL); + if (!fs_names) + return -EINVAL; + split_fs_names(fs_names, root_fs_names); + + for (fstype = fs_names; *fstype; fstype += strlen(fstype) + 1) { + if (!fs_is_nodev(fstype)) + continue; + err = do_mount_root(root_device_name, fstype, root_mountflags, + root_mount_data); + if (!err) + break; + if (err != -EACCES && err != -EINVAL) + panic("VFS: Unable to mount root \"%s\" (%s), err=%d\n", + root_device_name, fstype, err); + } + + free_page((unsigned long)fs_names); + return err; +} + void __init mount_root(void) { #ifdef CONFIG_ROOT_NFS @@ -550,6 +589,10 @@ void __init mount_root(void) return; } #endif + if (ROOT_DEV == 0 && root_device_name && root_fs_names) { + if (mount_nodev_root() == 0) + return; + } #ifdef CONFIG_BLOCK { int err = create_dev("/dev/root", ROOT_DEV); -- cgit v1.2.3-70-g09d2 From 6e7c1770a212239e88ec01ddc7a741505bfd10e5 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 14 Jul 2021 16:23:21 -0400 Subject: fs: simplify get_filesystem_list / get_all_fs_names Just output the '\0' separate list of supported file systems for block devices directly rather than going through a pointless round of string manipulation. Based on an earlier patch from Al Viro . Vivek: Modified list_bdev_fs_names() and split_fs_names() to return number of null terminted strings to caller. Callers now use that information to loop through all the strings instead of relying on one extra null char being present at the end. Signed-off-by: Christoph Hellwig Signed-off-by: Vivek Goyal Signed-off-by: Al Viro --- fs/filesystems.c | 27 +++++++++++++++++---------- include/linux/fs.h | 2 +- init/do_mounts.c | 49 +++++++++++++++++++++---------------------------- 3 files changed, 39 insertions(+), 39 deletions(-) (limited to 'init') diff --git a/fs/filesystems.c b/fs/filesystems.c index 90b8d879fbaf..58b9067b2391 100644 --- a/fs/filesystems.c +++ b/fs/filesystems.c @@ -209,21 +209,28 @@ SYSCALL_DEFINE3(sysfs, int, option, unsigned long, arg1, unsigned long, arg2) } #endif -int __init get_filesystem_list(char *buf) +int __init list_bdev_fs_names(char *buf, size_t size) { - int len = 0; - struct file_system_type * tmp; + struct file_system_type *p; + size_t len; + int count = 0; read_lock(&file_systems_lock); - tmp = file_systems; - while (tmp && len < PAGE_SIZE - 80) { - len += sprintf(buf+len, "%s\t%s\n", - (tmp->fs_flags & FS_REQUIRES_DEV) ? "" : "nodev", - tmp->name); - tmp = tmp->next; + for (p = file_systems; p; p = p->next) { + if (!(p->fs_flags & FS_REQUIRES_DEV)) + continue; + len = strlen(p->name) + 1; + if (len > size) { + pr_warn("%s: truncating file system list\n", __func__); + break; + } + memcpy(buf, p->name, len); + buf += len; + size -= len; + count++; } read_unlock(&file_systems_lock); - return len; + return count; } #ifdef CONFIG_PROC_FS diff --git a/include/linux/fs.h b/include/linux/fs.h index 640574294216..c76dfc01cf9d 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -3622,7 +3622,7 @@ int proc_nr_dentry(struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos); int proc_nr_inodes(struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos); -int __init get_filesystem_list(char *buf); +int __init list_bdev_fs_names(char *buf, size_t size); #define __FMODE_EXEC ((__force int) FMODE_EXEC) #define __FMODE_NONOTIFY ((__force int) FMODE_NONOTIFY) diff --git a/init/do_mounts.c b/init/do_mounts.c index bdeb90b8d669..9b4a1f877e47 100644 --- a/init/do_mounts.c +++ b/init/do_mounts.c @@ -338,32 +338,22 @@ __setup("rootflags=", root_data_setup); __setup("rootfstype=", fs_names_setup); __setup("rootdelay=", root_delay_setup); -static void __init split_fs_names(char *page, char *names) +static int __init split_fs_names(char *page, char *names) { - strcpy(page, root_fs_names); - while (*page++) { - if (page[-1] == ',') - page[-1] = '\0'; - } - *page = '\0'; -} - -static void __init get_all_fs_names(char *page) -{ - int len = get_filesystem_list(page); - char *s = page, *p, *next; + int count = 0; + char *p = page; - page[len] = '\0'; - for (p = page - 1; p; p = next) { - next = strchr(++p, '\n'); - if (*p++ != '\t') - continue; - while ((*s++ = *p++) != '\n') - ; - s[-1] = '\0'; + strcpy(p, root_fs_names); + while (*p++) { + if (p[-1] == ',') + p[-1] = '\0'; } + *p = '\0'; + + for (p = page; *p; p += strlen(p)+1) + count++; - *s = '\0'; + return count; } static int __init do_mount_root(const char *name, const char *fs, @@ -409,15 +399,16 @@ void __init mount_block_root(char *name, int flags) char *fs_names = page_address(page); char *p; char b[BDEVNAME_SIZE]; + int num_fs, i; scnprintf(b, BDEVNAME_SIZE, "unknown-block(%u,%u)", MAJOR(ROOT_DEV), MINOR(ROOT_DEV)); if (root_fs_names) - split_fs_names(fs_names, root_fs_names); + num_fs = split_fs_names(fs_names, root_fs_names); else - get_all_fs_names(fs_names); + num_fs = list_bdev_fs_names(fs_names, PAGE_SIZE); retry: - for (p = fs_names; *p; p += strlen(p)+1) { + for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1) { int err = do_mount_root(name, p, flags, root_mount_data); switch (err) { case 0: @@ -450,7 +441,7 @@ retry: printk("List of all partitions:\n"); printk_all_partitions(); printk("No filesystem could mount root, tried: "); - for (p = fs_names; *p; p += strlen(p)+1) + for (i = 0, p = fs_names; i < num_fs; i++, p += strlen(p)+1) printk(" %s", p); printk("\n"); panic("VFS: Unable to mount root fs on %s", b); @@ -551,13 +542,15 @@ static int __init mount_nodev_root(void) { char *fs_names, *fstype; int err = -EINVAL; + int num_fs, i; fs_names = (void *)__get_free_page(GFP_KERNEL); if (!fs_names) return -EINVAL; - split_fs_names(fs_names, root_fs_names); + num_fs = split_fs_names(fs_names, root_fs_names); - for (fstype = fs_names; *fstype; fstype += strlen(fstype) + 1) { + for (i = 0, fstype = fs_names; i < num_fs; + i++, fstype += strlen(fstype) + 1) { if (!fs_is_nodev(fstype)) continue; err = do_mount_root(root_device_name, fstype, root_mountflags, -- cgit v1.2.3-70-g09d2