diff options
Diffstat (limited to 'fs/namespace.c')
| -rw-r--r-- | fs/namespace.c | 265 |
1 files changed, 233 insertions, 32 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 1bf302d0478b..0505fb61aa74 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -27,6 +27,7 @@ #include <linux/mount.h> #include <linux/ramfs.h> #include <linux/log2.h> +#include <linux/idr.h> #include <asm/uaccess.h> #include <asm/unistd.h> #include "pnode.h" @@ -39,6 +40,8 @@ __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock); static int event; +static DEFINE_IDA(mnt_id_ida); +static DEFINE_IDA(mnt_group_ida); static struct list_head *mount_hashtable __read_mostly; static struct kmem_cache *mnt_cache __read_mostly; @@ -58,10 +61,63 @@ static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry) #define MNT_WRITER_UNDERFLOW_LIMIT -(1<<16) +/* allocation is serialized by namespace_sem */ +static int mnt_alloc_id(struct vfsmount *mnt) +{ + int res; + +retry: + ida_pre_get(&mnt_id_ida, GFP_KERNEL); + spin_lock(&vfsmount_lock); + res = ida_get_new(&mnt_id_ida, &mnt->mnt_id); + spin_unlock(&vfsmount_lock); + if (res == -EAGAIN) + goto retry; + + return res; +} + +static void mnt_free_id(struct vfsmount *mnt) +{ + spin_lock(&vfsmount_lock); + ida_remove(&mnt_id_ida, mnt->mnt_id); + spin_unlock(&vfsmount_lock); +} + +/* + * Allocate a new peer group ID + * + * mnt_group_ida is protected by namespace_sem + */ +static int mnt_alloc_group_id(struct vfsmount *mnt) +{ + if (!ida_pre_get(&mnt_group_ida, GFP_KERNEL)) + return -ENOMEM; + + return ida_get_new_above(&mnt_group_ida, 1, &mnt->mnt_group_id); +} + +/* + * Release a peer group ID + */ +void mnt_release_group_id(struct vfsmount *mnt) +{ + ida_remove(&mnt_group_ida, mnt->mnt_group_id); + mnt->mnt_group_id = 0; +} + struct vfsmount *alloc_vfsmnt(const char *name) { struct vfsmount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL); if (mnt) { + int err; + + err = mnt_alloc_id(mnt); + if (err) { + kmem_cache_free(mnt_cache, mnt); + return NULL; + } + atomic_set(&mnt->mnt_count, 1); INIT_LIST_HEAD(&mnt->mnt_hash); INIT_LIST_HEAD(&mnt->mnt_child); @@ -353,6 +409,7 @@ EXPORT_SYMBOL(simple_set_mnt); void free_vfsmnt(struct vfsmount *mnt) { kfree(mnt->mnt_devname); + mnt_free_id(mnt); kmem_cache_free(mnt_cache, mnt); } @@ -499,6 +556,17 @@ static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root, struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname); if (mnt) { + if (flag & (CL_SLAVE | CL_PRIVATE)) + mnt->mnt_group_id = 0; /* not a peer of original */ + else + mnt->mnt_group_id = old->mnt_group_id; + + if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) { + int err = mnt_alloc_group_id(mnt); + if (err) + goto out_free; + } + mnt->mnt_flags = old->mnt_flags; atomic_inc(&sb->s_active); mnt->mnt_sb = sb; @@ -528,6 +596,10 @@ static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root, } } return mnt; + + out_free: + free_vfsmnt(mnt); + return NULL; } static inline void __mntput(struct vfsmount *mnt) @@ -652,20 +724,21 @@ void save_mount_options(struct super_block *sb, char *options) } EXPORT_SYMBOL(save_mount_options); +#ifdef CONFIG_PROC_FS /* iterator */ static void *m_start(struct seq_file *m, loff_t *pos) { - struct mnt_namespace *n = m->private; + struct proc_mounts *p = m->private; down_read(&namespace_sem); - return seq_list_start(&n->list, *pos); + return seq_list_start(&p->ns->list, *pos); } static void *m_next(struct seq_file *m, void *v, loff_t *pos) { - struct mnt_namespace *n = m->private; + struct proc_mounts *p = m->private; - return seq_list_next(v, &n->list, pos); + return seq_list_next(v, &p->ns->list, pos); } static void m_stop(struct seq_file *m, void *v) @@ -673,20 +746,30 @@ static void m_stop(struct seq_file *m, void *v) up_read(&namespace_sem); } -static int show_vfsmnt(struct seq_file *m, void *v) +struct proc_fs_info { + int flag; + const char *str; +}; + +static void show_sb_opts(struct seq_file *m, struct super_block *sb) { - struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); - int err = 0; - static struct proc_fs_info { - int flag; - char *str; - } fs_info[] = { + static const struct proc_fs_info fs_info[] = { { MS_SYNCHRONOUS, ",sync" }, { MS_DIRSYNC, ",dirsync" }, { MS_MANDLOCK, ",mand" }, { 0, NULL } }; - static struct proc_fs_info mnt_info[] = { + const struct proc_fs_info *fs_infop; + + for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { + if (sb->s_flags & fs_infop->flag) + seq_puts(m, fs_infop->str); + } +} + +static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt) +{ + static const struct proc_fs_info mnt_info[] = { { MNT_NOSUID, ",nosuid" }, { MNT_NODEV, ",nodev" }, { MNT_NOEXEC, ",noexec" }, @@ -695,40 +778,108 @@ static int show_vfsmnt(struct seq_file *m, void *v) { MNT_RELATIME, ",relatime" }, { 0, NULL } }; - struct proc_fs_info *fs_infop; + const struct proc_fs_info *fs_infop; + + for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) { + if (mnt->mnt_flags & fs_infop->flag) + seq_puts(m, fs_infop->str); + } +} + +static void show_type(struct seq_file *m, struct super_block *sb) +{ + mangle(m, sb->s_type->name); + if (sb->s_subtype && sb->s_subtype[0]) { + seq_putc(m, '.'); + mangle(m, sb->s_subtype); + } +} + +static int show_vfsmnt(struct seq_file *m, void *v) +{ + struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); + int err = 0; struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); seq_putc(m, ' '); seq_path(m, &mnt_path, " \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); - } + show_type(m, mnt->mnt_sb); seq_puts(m, __mnt_is_readonly(mnt) ? " ro" : " rw"); - for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { - if (mnt->mnt_sb->s_flags & fs_infop->flag) - seq_puts(m, fs_infop->str); - } - for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) { - if (mnt->mnt_flags & fs_infop->flag) - seq_puts(m, fs_infop->str); - } + show_sb_opts(m, mnt->mnt_sb); + show_mnt_opts(m, mnt); if (mnt->mnt_sb->s_op->show_options) err = mnt->mnt_sb->s_op->show_options(m, mnt); seq_puts(m, " 0 0\n"); return err; } -struct seq_operations mounts_op = { +const struct seq_operations mounts_op = { .start = m_start, .next = m_next, .stop = m_stop, .show = show_vfsmnt }; +static int show_mountinfo(struct seq_file *m, void *v) +{ + struct proc_mounts *p = m->private; + struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); + struct super_block *sb = mnt->mnt_sb; + struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt }; + struct path root = p->root; + int err = 0; + + seq_printf(m, "%i %i %u:%u ", mnt->mnt_id, mnt->mnt_parent->mnt_id, + MAJOR(sb->s_dev), MINOR(sb->s_dev)); + seq_dentry(m, mnt->mnt_root, " \t\n\\"); + seq_putc(m, ' '); + seq_path_root(m, &mnt_path, &root, " \t\n\\"); + if (root.mnt != p->root.mnt || root.dentry != p->root.dentry) { + /* + * Mountpoint is outside root, discard that one. Ugly, + * but less so than trying to do that in iterator in a + * race-free way (due to renames). + */ + return SEQ_SKIP; + } + seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw"); + show_mnt_opts(m, mnt); + + /* Tagged fields ("foo:X" or "bar") */ + if (IS_MNT_SHARED(mnt)) + seq_printf(m, " shared:%i", mnt->mnt_group_id); + if (IS_MNT_SLAVE(mnt)) { + int master = mnt->mnt_master->mnt_group_id; + int dom = get_dominating_id(mnt, &p->root); + seq_printf(m, " master:%i", master); + if (dom && dom != master) + seq_printf(m, " propagate_from:%i", dom); + } + if (IS_MNT_UNBINDABLE(mnt)) + seq_puts(m, " unbindable"); + + /* Filesystem specific data */ + seq_puts(m, " - "); + show_type(m, sb); + seq_putc(m, ' '); + mangle(m, mnt->mnt_devname ? mnt->mnt_devname : "none"); + seq_puts(m, sb->s_flags & MS_RDONLY ? " ro" : " rw"); + show_sb_opts(m, sb); + if (sb->s_op->show_options) + err = sb->s_op->show_options(m, mnt); + seq_putc(m, '\n'); + return err; +} + +const struct seq_operations mountinfo_op = { + .start = m_start, + .next = m_next, + .stop = m_stop, + .show = show_mountinfo, +}; + static int show_vfsstat(struct seq_file *m, void *v) { struct vfsmount *mnt = list_entry(v, struct vfsmount, mnt_list); @@ -749,7 +900,7 @@ static int show_vfsstat(struct seq_file *m, void *v) /* file system type */ seq_puts(m, "with fstype "); - mangle(m, mnt->mnt_sb->s_type->name); + show_type(m, mnt->mnt_sb); /* optional statistics */ if (mnt->mnt_sb->s_op->show_stats) { @@ -761,12 +912,13 @@ static int show_vfsstat(struct seq_file *m, void *v) return err; } -struct seq_operations mountstats_op = { +const struct seq_operations mountstats_op = { .start = m_start, .next = m_next, .stop = m_stop, .show = show_vfsstat, }; +#endif /* CONFIG_PROC_FS */ /** * may_umount_tree - check if a mount tree is busy @@ -1108,6 +1260,33 @@ void drop_collected_mounts(struct vfsmount *mnt) release_mounts(&umount_list); } +static void cleanup_group_ids(struct vfsmount *mnt, struct vfsmount *end) +{ + struct vfsmount *p; + + for (p = mnt; p != end; p = next_mnt(p, mnt)) { + if (p->mnt_group_id && !IS_MNT_SHARED(p)) + mnt_release_group_id(p); + } +} + +static int invent_group_ids(struct vfsmount *mnt, bool recurse) +{ + struct vfsmount *p; + + for (p = mnt; p; p = recurse ? next_mnt(p, mnt) : NULL) { + if (!p->mnt_group_id && !IS_MNT_SHARED(p)) { + int err = mnt_alloc_group_id(p); + if (err) { + cleanup_group_ids(mnt, p); + return err; + } + } + } + + return 0; +} + /* * @source_mnt : mount tree to be attached * @nd : place the mount tree @source_mnt is attached @@ -1178,9 +1357,16 @@ static int attach_recursive_mnt(struct vfsmount *source_mnt, struct vfsmount *dest_mnt = path->mnt; struct dentry *dest_dentry = path->dentry; struct vfsmount *child, *p; + int err; - if (propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list)) - return -EINVAL; + if (IS_MNT_SHARED(dest_mnt)) { + err = invent_group_ids(source_mnt, true); + if (err) + goto out; + } + err = propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list); + if (err) + goto out_cleanup_ids; if (IS_MNT_SHARED(dest_mnt)) { for (p = source_mnt; p; p = next_mnt(p, source_mnt)) @@ -1203,6 +1389,12 @@ static int attach_recursive_mnt(struct vfsmount *source_mnt, } spin_unlock(&vfsmount_lock); return 0; + + out_cleanup_ids: + if (IS_MNT_SHARED(dest_mnt)) + cleanup_group_ids(source_mnt, NULL); + out: + return err; } static int graft_tree(struct vfsmount *mnt, struct path *path) @@ -1243,6 +1435,7 @@ static noinline int do_change_type(struct nameidata *nd, int flag) struct vfsmount *m, *mnt = nd->path.mnt; int recurse = flag & MS_REC; int type = flag & ~MS_REC; + int err = 0; if (!capable(CAP_SYS_ADMIN)) return -EPERM; @@ -1251,12 +1444,20 @@ static noinline int do_change_type(struct nameidata *nd, int flag) return -EINVAL; down_write(&namespace_sem); + if (type == MS_SHARED) { + err = invent_group_ids(mnt, recurse); + if (err) + goto out_unlock; + } + spin_lock(&vfsmount_lock); for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) change_mnt_propagation(m, type); spin_unlock(&vfsmount_lock); + + out_unlock: up_write(&namespace_sem); - return 0; + return err; } /* |