From 79c0b2df79eb56fc71e54c75cd7fb3acf84370f9 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Tue, 8 May 2007 00:25:43 -0700 Subject: [PATCH] add filesystem subtype support There's a slight problem with filesystem type representation in fuse based filesystems. From the kernel's view, there are just two filesystem types: fuse and fuseblk. From the user's view there are lots of different filesystem types. The user is not even much concerned if the filesystem is fuse based or not. So there's a conflict of interest in how this should be represented in fstab, mtab and /proc/mounts. The current scheme is to encode the real filesystem type in the mount source. So an sshfs mount looks like this: sshfs#user@server:/ /mnt/server fuse rw,nosuid,nodev,... This url-ish syntax works OK for sshfs and similar filesystems. However for block device based filesystems (ntfs-3g, zfs) it doesn't work, since the kernel expects the mount source to be a real device name. A possibly better scheme would be to encode the real type in the type field as "type.subtype". So fuse mounts would look like this: /dev/hda1 /mnt/windows fuseblk.ntfs-3g rw,... user@server:/ /mnt/server fuse.sshfs rw,nosuid,nodev,... This patch adds the necessary code to the kernel so that this can be correctly displayed in /proc/mounts. Signed-off-by: Miklos Szeredi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/filesystems.c | 21 +++++++++++++++------ fs/fuse/inode.c | 2 ++ fs/namespace.c | 4 ++++ fs/super.c | 27 +++++++++++++++++++++++++++ include/linux/fs.h | 7 +++++++ 5 files changed, 55 insertions(+), 6 deletions(-) diff --git a/fs/filesystems.c b/fs/filesystems.c index 7a4f61aa05f8..f37f87262837 100644 --- a/fs/filesystems.c +++ b/fs/filesystems.c @@ -41,11 +41,12 @@ void put_filesystem(struct file_system_type *fs) module_put(fs->owner); } -static struct file_system_type **find_filesystem(const char *name) +static struct file_system_type **find_filesystem(const char *name, unsigned len) { struct file_system_type **p; for (p=&file_systems; *p; p=&(*p)->next) - if (strcmp((*p)->name,name) == 0) + if (strlen((*p)->name) == len && + strncmp((*p)->name, name, len) == 0) break; return p; } @@ -68,11 +69,12 @@ int register_filesystem(struct file_system_type * fs) int res = 0; struct file_system_type ** p; + BUG_ON(strchr(fs->name, '.')); if (fs->next) return -EBUSY; INIT_LIST_HEAD(&fs->fs_supers); write_lock(&file_systems_lock); - p = find_filesystem(fs->name); + p = find_filesystem(fs->name, strlen(fs->name)); if (*p) res = -EBUSY; else @@ -215,19 +217,26 @@ int get_filesystem_list(char * buf) struct file_system_type *get_fs_type(const char *name) { struct file_system_type *fs; + const char *dot = strchr(name, '.'); + unsigned len = dot ? dot - name : strlen(name); read_lock(&file_systems_lock); - fs = *(find_filesystem(name)); + fs = *(find_filesystem(name, len)); if (fs && !try_module_get(fs->owner)) fs = NULL; read_unlock(&file_systems_lock); - if (!fs && (request_module("%s", name) == 0)) { + if (!fs && (request_module("%.*s", len, name) == 0)) { read_lock(&file_systems_lock); - fs = *(find_filesystem(name)); + fs = *(find_filesystem(name, len)); if (fs && !try_module_get(fs->owner)) fs = NULL; read_unlock(&file_systems_lock); } + + if (dot && fs && !(fs->fs_flags & FS_HAS_SUBTYPE)) { + put_filesystem(fs); + fs = NULL; + } return fs; } diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c index d8003be56e05..1397018ff476 100644 --- a/fs/fuse/inode.c +++ b/fs/fuse/inode.c @@ -636,6 +636,7 @@ static int fuse_get_sb(struct file_system_type *fs_type, static struct file_system_type fuse_fs_type = { .owner = THIS_MODULE, .name = "fuse", + .fs_flags = FS_HAS_SUBTYPE, .get_sb = fuse_get_sb, .kill_sb = kill_anon_super, }; @@ -652,6 +653,7 @@ static int fuse_get_sb_blk(struct file_system_type *fs_type, static struct file_system_type fuseblk_fs_type = { .owner = THIS_MODULE, .name = "fuseblk", + .fs_flags = FS_HAS_SUBTYPE, .get_sb = fuse_get_sb_blk, .kill_sb = kill_block_super, .fs_flags = FS_REQUIRES_DEV, diff --git a/fs/namespace.c b/fs/namespace.c index be5e56bfb73e..c5b88100d914 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -377,6 +377,10 @@ static int show_vfsmnt(struct seq_file *m, void *v) seq_path(m, mnt, mnt->mnt_root, " \t\n\\"); seq_putc(m, ' '); mangle(m, mnt->mnt_sb->s_type->name); + if (mnt->mnt_sb->s_subtype && mnt->mnt_sb->s_subtype[0]) { + seq_putc(m, '.'); + mangle(m, mnt->mnt_sb->s_subtype); + } seq_puts(m, mnt->mnt_sb->s_flags & MS_RDONLY ? " ro" : " rw"); for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { if (mnt->mnt_sb->s_flags & fs_infop->flag) diff --git a/fs/super.c b/fs/super.c index 8341e4e1d738..5260d620c555 100644 --- a/fs/super.c +++ b/fs/super.c @@ -107,6 +107,7 @@ out: static inline void destroy_super(struct super_block *s) { security_sb_free(s); + kfree(s->s_subtype); kfree(s); } @@ -907,6 +908,29 @@ out: EXPORT_SYMBOL_GPL(vfs_kern_mount); +static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype) +{ + int err; + const char *subtype = strchr(fstype, '.'); + if (subtype) { + subtype++; + err = -EINVAL; + if (!subtype[0]) + goto err; + } else + subtype = ""; + + mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL); + err = -ENOMEM; + if (!mnt->mnt_sb->s_subtype) + goto err; + return mnt; + + err: + mntput(mnt); + return ERR_PTR(err); +} + struct vfsmount * do_kern_mount(const char *fstype, int flags, const char *name, void *data) { @@ -915,6 +939,9 @@ do_kern_mount(const char *fstype, int flags, const char *name, void *data) if (!type) return ERR_PTR(-ENODEV); mnt = vfs_kern_mount(type, flags, name, data); + if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) && + !mnt->mnt_sb->s_subtype) + mnt = fs_set_subtype(mnt, fstype); put_filesystem(type); return mnt; } diff --git a/include/linux/fs.h b/include/linux/fs.h index 986b5d5d369f..527a09a82297 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -92,6 +92,7 @@ extern int dir_notify_enable; /* public flags for file_system_type */ #define FS_REQUIRES_DEV 1 #define FS_BINARY_MOUNTDATA 2 +#define FS_HAS_SUBTYPE 4 #define FS_REVAL_DOT 16384 /* Check the paths ".", ".." for staleness */ #define FS_RENAME_DOES_D_MOVE 32768 /* FS will handle d_move() * during rename() internally. @@ -961,6 +962,12 @@ struct super_block { /* Granularity of c/m/atime in ns. Cannot be worse than a second */ u32 s_time_gran; + + /* + * Filesystem subtype. If non-empty the filesystem type field + * in /proc/mounts will be "type.subtype" + */ + char *s_subtype; }; extern struct timespec current_fs_time(struct super_block *sb); -- 2.20.1