diff options
Diffstat (limited to 'fs/namespace.c')
| -rw-r--r-- | fs/namespace.c | 581 |
1 files changed, 324 insertions, 257 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index da5c4948343..182bc41cd88 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -23,23 +23,46 @@ #include <linux/uaccess.h> #include <linux/proc_ns.h> #include <linux/magic.h> +#include <linux/bootmem.h> #include "pnode.h" #include "internal.h" -#define HASH_SHIFT ilog2(PAGE_SIZE / sizeof(struct list_head)) -#define HASH_SIZE (1UL << HASH_SHIFT) +static unsigned int m_hash_mask __read_mostly; +static unsigned int m_hash_shift __read_mostly; +static unsigned int mp_hash_mask __read_mostly; +static unsigned int mp_hash_shift __read_mostly; -static int event; +static __initdata unsigned long mhash_entries; +static int __init set_mhash_entries(char *str) +{ + if (!str) + return 0; + mhash_entries = simple_strtoul(str, &str, 0); + return 1; +} +__setup("mhash_entries=", set_mhash_entries); + +static __initdata unsigned long mphash_entries; +static int __init set_mphash_entries(char *str) +{ + if (!str) + return 0; + mphash_entries = simple_strtoul(str, &str, 0); + return 1; +} +__setup("mphash_entries=", set_mphash_entries); + +static u64 event; static DEFINE_IDA(mnt_id_ida); static DEFINE_IDA(mnt_group_ida); static DEFINE_SPINLOCK(mnt_id_lock); static int mnt_id_start = 0; static int mnt_group_start = 1; -static struct list_head *mount_hashtable __read_mostly; -static struct list_head *mountpoint_hashtable __read_mostly; +static struct hlist_head *mount_hashtable __read_mostly; +static struct hlist_head *mountpoint_hashtable __read_mostly; static struct kmem_cache *mnt_cache __read_mostly; -static struct rw_semaphore namespace_sem; +static DECLARE_RWSEM(namespace_sem); /* /sys/fs */ struct kobject *fs_kobj; @@ -53,17 +76,22 @@ EXPORT_SYMBOL_GPL(fs_kobj); * It should be taken for write in all cases where the vfsmount * tree or hash is modified or when a vfsmount structure is modified. */ -DEFINE_BRLOCK(vfsmount_lock); +__cacheline_aligned_in_smp DEFINE_SEQLOCK(mount_lock); -static inline unsigned long hash(struct vfsmount *mnt, struct dentry *dentry) +static inline struct hlist_head *m_hash(struct vfsmount *mnt, struct dentry *dentry) { unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES); tmp += ((unsigned long)dentry / L1_CACHE_BYTES); - tmp = tmp + (tmp >> HASH_SHIFT); - return tmp & (HASH_SIZE - 1); + tmp = tmp + (tmp >> m_hash_shift); + return &mount_hashtable[tmp & m_hash_mask]; } -#define MNT_WRITER_UNDERFLOW_LIMIT -(1<<16) +static inline struct hlist_head *mp_hash(struct dentry *dentry) +{ + unsigned long tmp = ((unsigned long)dentry / L1_CACHE_BYTES); + tmp = tmp + (tmp >> mp_hash_shift); + return &mountpoint_hashtable[tmp & mp_hash_mask]; +} /* * allocation is serialized by namespace_sem, but we need the spinlock to @@ -189,7 +217,7 @@ static struct mount *alloc_vfsmnt(const char *name) mnt->mnt_writers = 0; #endif - INIT_LIST_HEAD(&mnt->mnt_hash); + INIT_HLIST_NODE(&mnt->mnt_hash); INIT_LIST_HEAD(&mnt->mnt_child); INIT_LIST_HEAD(&mnt->mnt_mounts); INIT_LIST_HEAD(&mnt->mnt_list); @@ -386,9 +414,7 @@ EXPORT_SYMBOL_GPL(mnt_clone_write); */ int __mnt_want_write_file(struct file *file) { - struct inode *inode = file_inode(file); - - if (!(file->f_mode & FMODE_WRITE) || special_file(inode->i_mode)) + if (!(file->f_mode & FMODE_WRITER)) return __mnt_want_write(file->f_path.mnt); else return mnt_clone_write(file->f_path.mnt); @@ -458,7 +484,7 @@ static int mnt_make_readonly(struct mount *mnt) { int ret = 0; - br_write_lock(&vfsmount_lock); + lock_mount_hash(); mnt->mnt.mnt_flags |= MNT_WRITE_HOLD; /* * After storing MNT_WRITE_HOLD, we'll read the counters. This store @@ -492,15 +518,15 @@ static int mnt_make_readonly(struct mount *mnt) */ smp_wmb(); mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD; - br_write_unlock(&vfsmount_lock); + unlock_mount_hash(); return ret; } static void __mnt_unmake_readonly(struct mount *mnt) { - br_write_lock(&vfsmount_lock); + lock_mount_hash(); mnt->mnt.mnt_flags &= ~MNT_READONLY; - br_write_unlock(&vfsmount_lock); + unlock_mount_hash(); } int sb_prepare_remount_readonly(struct super_block *sb) @@ -512,7 +538,7 @@ int sb_prepare_remount_readonly(struct super_block *sb) if (atomic_long_read(&sb->s_remove_count)) return -EBUSY; - br_write_lock(&vfsmount_lock); + lock_mount_hash(); list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) { if (!(mnt->mnt.mnt_flags & MNT_READONLY)) { mnt->mnt.mnt_flags |= MNT_WRITE_HOLD; @@ -534,7 +560,7 @@ int sb_prepare_remount_readonly(struct super_block *sb) if (mnt->mnt.mnt_flags & MNT_WRITE_HOLD) mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD; } - br_write_unlock(&vfsmount_lock); + unlock_mount_hash(); return err; } @@ -542,37 +568,71 @@ int sb_prepare_remount_readonly(struct super_block *sb) static void free_vfsmnt(struct mount *mnt) { kfree(mnt->mnt_devname); - mnt_free_id(mnt); #ifdef CONFIG_SMP free_percpu(mnt->mnt_pcp); #endif kmem_cache_free(mnt_cache, mnt); } +static void delayed_free_vfsmnt(struct rcu_head *head) +{ + free_vfsmnt(container_of(head, struct mount, mnt_rcu)); +} + +/* call under rcu_read_lock */ +bool legitimize_mnt(struct vfsmount *bastard, unsigned seq) +{ + struct mount *mnt; + if (read_seqretry(&mount_lock, seq)) + return false; + if (bastard == NULL) + return true; + mnt = real_mount(bastard); + mnt_add_count(mnt, 1); + if (likely(!read_seqretry(&mount_lock, seq))) + return true; + if (bastard->mnt_flags & MNT_SYNC_UMOUNT) { + mnt_add_count(mnt, -1); + return false; + } + rcu_read_unlock(); + mntput(bastard); + rcu_read_lock(); + return false; +} + /* - * find the first or last mount at @dentry on vfsmount @mnt depending on - * @dir. If @dir is set return the first mount else return the last mount. - * vfsmount_lock must be held for read or write. + * find the first mount at @dentry on vfsmount @mnt. + * call under rcu_read_lock() */ -struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry, - int dir) +struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry) { - struct list_head *head = mount_hashtable + hash(mnt, dentry); - struct list_head *tmp = head; - struct mount *p, *found = NULL; + struct hlist_head *head = m_hash(mnt, dentry); + struct mount *p; - for (;;) { - tmp = dir ? tmp->next : tmp->prev; - p = NULL; - if (tmp == head) - break; - p = list_entry(tmp, struct mount, mnt_hash); - if (&p->mnt_parent->mnt == mnt && p->mnt_mountpoint == dentry) { - found = p; + hlist_for_each_entry_rcu(p, head, mnt_hash) + if (&p->mnt_parent->mnt == mnt && p->mnt_mountpoint == dentry) + return p; + return NULL; +} + +/* + * find the last mount at @dentry on vfsmount @mnt. + * mount_lock must be held. + */ +struct mount *__lookup_mnt_last(struct vfsmount *mnt, struct dentry *dentry) +{ + struct mount *p, *res; + res = p = __lookup_mnt(mnt, dentry); + if (!p) + goto out; + hlist_for_each_entry_continue(p, mnt_hash) { + if (&p->mnt_parent->mnt != mnt || p->mnt_mountpoint != dentry) break; - } + res = p; } - return found; +out: + return res; } /* @@ -594,26 +654,26 @@ struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry, struct vfsmount *lookup_mnt(struct path *path) { struct mount *child_mnt; + struct vfsmount *m; + unsigned seq; - br_read_lock(&vfsmount_lock); - child_mnt = __lookup_mnt(path->mnt, path->dentry, 1); - if (child_mnt) { - mnt_add_count(child_mnt, 1); - br_read_unlock(&vfsmount_lock); - return &child_mnt->mnt; - } else { - br_read_unlock(&vfsmount_lock); - return NULL; - } + rcu_read_lock(); + do { + seq = read_seqbegin(&mount_lock); + child_mnt = __lookup_mnt(path->mnt, path->dentry); + m = child_mnt ? &child_mnt->mnt : NULL; + } while (!legitimize_mnt(m, seq)); + rcu_read_unlock(); + return m; } static struct mountpoint *new_mountpoint(struct dentry *dentry) { - struct list_head *chain = mountpoint_hashtable + hash(NULL, dentry); + struct hlist_head *chain = mp_hash(dentry); struct mountpoint *mp; int ret; - list_for_each_entry(mp, chain, m_hash) { + hlist_for_each_entry(mp, chain, m_hash) { if (mp->m_dentry == dentry) { /* might be worth a WARN_ON() */ if (d_unlinked(dentry)) @@ -635,7 +695,7 @@ static struct mountpoint *new_mountpoint(struct dentry *dentry) mp->m_dentry = dentry; mp->m_count = 1; - list_add(&mp->m_hash, chain); + hlist_add_head(&mp->m_hash, chain); return mp; } @@ -646,7 +706,7 @@ static void put_mountpoint(struct mountpoint *mp) spin_lock(&dentry->d_lock); dentry->d_flags &= ~DCACHE_MOUNTED; spin_unlock(&dentry->d_lock); - list_del(&mp->m_hash); + hlist_del(&mp->m_hash); kfree(mp); } } @@ -688,7 +748,7 @@ static void detach_mnt(struct mount *mnt, struct path *old_path) mnt->mnt_parent = mnt; mnt->mnt_mountpoint = mnt->mnt.mnt_root; list_del_init(&mnt->mnt_child); - list_del_init(&mnt->mnt_hash); + hlist_del_init_rcu(&mnt->mnt_hash); put_mountpoint(mnt->mnt_mp); mnt->mnt_mp = NULL; } @@ -715,15 +775,14 @@ static void attach_mnt(struct mount *mnt, struct mountpoint *mp) { mnt_set_mountpoint(parent, mp, mnt); - list_add_tail(&mnt->mnt_hash, mount_hashtable + - hash(&parent->mnt, mp->m_dentry)); + hlist_add_head_rcu(&mnt->mnt_hash, m_hash(&parent->mnt, mp->m_dentry)); list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); } /* * vfsmount lock must be held for write */ -static void commit_tree(struct mount *mnt) +static void commit_tree(struct mount *mnt, struct mount *shadows) { struct mount *parent = mnt->mnt_parent; struct mount *m; @@ -738,8 +797,11 @@ static void commit_tree(struct mount *mnt) list_splice(&head, n->list.prev); - list_add_tail(&mnt->mnt_hash, mount_hashtable + - hash(&parent->mnt, mnt->mnt_mountpoint)); + if (shadows) + hlist_add_after_rcu(&shadows->mnt_hash, &mnt->mnt_hash); + else + hlist_add_head_rcu(&mnt->mnt_hash, + m_hash(&parent->mnt, mnt->mnt_mountpoint)); list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); touch_mnt_namespace(n); } @@ -788,6 +850,7 @@ vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void root = mount_fs(type, flags, name, data); if (IS_ERR(root)) { + mnt_free_id(mnt); free_vfsmnt(mnt); return ERR_CAST(root); } @@ -796,9 +859,9 @@ vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void mnt->mnt.mnt_sb = root->d_sb; mnt->mnt_mountpoint = mnt->mnt.mnt_root; mnt->mnt_parent = mnt; - br_write_lock(&vfsmount_lock); + lock_mount_hash(); list_add_tail(&mnt->mnt_instance, &root->d_sb->s_mounts); - br_write_unlock(&vfsmount_lock); + unlock_mount_hash(); return &mnt->mnt; } EXPORT_SYMBOL_GPL(vfs_kern_mount); @@ -825,7 +888,7 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root, goto out_free; } - mnt->mnt.mnt_flags = old->mnt.mnt_flags & ~MNT_WRITE_HOLD; + mnt->mnt.mnt_flags = old->mnt.mnt_flags & ~(MNT_WRITE_HOLD|MNT_MARKED); /* Don't allow unprivileged users to change mount flags */ if ((flag & CL_UNPRIVILEGED) && (mnt->mnt.mnt_flags & MNT_READONLY)) mnt->mnt.mnt_flags |= MNT_LOCK_READONLY; @@ -839,9 +902,9 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root, mnt->mnt.mnt_root = dget(root); mnt->mnt_mountpoint = mnt->mnt.mnt_root; mnt->mnt_parent = mnt; - br_write_lock(&vfsmount_lock); + lock_mount_hash(); list_add_tail(&mnt->mnt_instance, &sb->s_mounts); - br_write_unlock(&vfsmount_lock); + unlock_mount_hash(); if ((flag & CL_SLAVE) || ((flag & CL_SHARED_TO_SLAVE) && IS_MNT_SHARED(old))) { @@ -868,68 +931,61 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root, return mnt; out_free: + mnt_free_id(mnt); free_vfsmnt(mnt); return ERR_PTR(err); } -static inline void mntfree(struct mount *mnt) -{ - struct vfsmount *m = &mnt->mnt; - struct super_block *sb = m->mnt_sb; - - /* - * This probably indicates that somebody messed - * up a mnt_want/drop_write() pair. If this - * happens, the filesystem was probably unable - * to make r/w->r/o transitions. - */ - /* - * The locking used to deal with mnt_count decrement provides barriers, - * so mnt_get_writers() below is safe. - */ - WARN_ON(mnt_get_writers(mnt)); - fsnotify_vfsmount_delete(m); - dput(m->mnt_root); - free_vfsmnt(mnt); - deactivate_super(sb); -} - static void mntput_no_expire(struct mount *mnt) { put_again: -#ifdef CONFIG_SMP - br_read_lock(&vfsmount_lock); - if (likely(mnt->mnt_ns)) { - /* shouldn't be the last one */ - mnt_add_count(mnt, -1); - br_read_unlock(&vfsmount_lock); + rcu_read_lock(); + mnt_add_count(mnt, -1); + if (likely(mnt->mnt_ns)) { /* shouldn't be the last one */ + rcu_read_unlock(); return; } - br_read_unlock(&vfsmount_lock); - - br_write_lock(&vfsmount_lock); - mnt_add_count(mnt, -1); + lock_mount_hash(); if (mnt_get_count(mnt)) { - br_write_unlock(&vfsmount_lock); + rcu_read_unlock(); + unlock_mount_hash(); return; } -#else - mnt_add_count(mnt, -1); - if (likely(mnt_get_count(mnt))) - return; - br_write_lock(&vfsmount_lock); -#endif if (unlikely(mnt->mnt_pinned)) { mnt_add_count(mnt, mnt->mnt_pinned + 1); mnt->mnt_pinned = 0; - br_write_unlock(&vfsmount_lock); + rcu_read_unlock(); + unlock_mount_hash(); acct_auto_close_mnt(&mnt->mnt); goto put_again; } + if (unlikely(mnt->mnt.mnt_flags & MNT_DOOMED)) { + rcu_read_unlock(); + unlock_mount_hash(); + return; + } + mnt->mnt.mnt_flags |= MNT_DOOMED; + rcu_read_unlock(); list_del(&mnt->mnt_instance); - br_write_unlock(&vfsmount_lock); - mntfree(mnt); + unlock_mount_hash(); + + /* + * This probably indicates that somebody messed + * up a mnt_want/drop_write() pair. If this + * happens, the filesystem was probably unable + * to make r/w->r/o transitions. + */ + /* + * The locking used to deal with mnt_count decrement provides barriers, + * so mnt_get_writers() below is safe. + */ + WARN_ON(mnt_get_writers(mnt)); + fsnotify_vfsmount_delete(&mnt->mnt); + dput(mnt->mnt.mnt_root); + deactivate_super(mnt->mnt.mnt_sb); + mnt_free_id(mnt); + call_rcu(&mnt->mnt_rcu, delayed_free_vfsmnt); } void mntput(struct vfsmount *mnt) @@ -954,21 +1010,21 @@ EXPORT_SYMBOL(mntget); void mnt_pin(struct vfsmount *mnt) { - br_write_lock(&vfsmount_lock); + lock_mount_hash(); real_mount(mnt)->mnt_pinned++; - br_write_unlock(&vfsmount_lock); + unlock_mount_hash(); } EXPORT_SYMBOL(mnt_pin); void mnt_unpin(struct vfsmount *m) { struct mount *mnt = real_mount(m); - br_write_lock(&vfsmount_lock); + lock_mount_hash(); if (mnt->mnt_pinned) { mnt_add_count(mnt, 1); mnt->mnt_pinned--; } - br_write_unlock(&vfsmount_lock); + unlock_mount_hash(); } EXPORT_SYMBOL(mnt_unpin); @@ -1038,14 +1094,29 @@ static void *m_start(struct seq_file *m, loff_t *pos) struct proc_mounts *p = proc_mounts(m); down_read(&namespace_sem); - return seq_list_start(&p->ns->list, *pos); + if (p->cached_event == p->ns->event) { + void *v = p->cached_mount; + if (*pos == p->cached_index) + return v; + if (*pos == p->cached_index + 1) { + v = seq_list_next(v, &p->ns->list, &p->cached_index); + return p->cached_mount = v; + } + } + + p->cached_event = p->ns->event; + p->cached_mount = seq_list_start(&p->ns->list, *pos); + p->cached_index = *pos; + return p->cached_mount; } static void *m_next(struct seq_file *m, void *v, loff_t *pos) { struct proc_mounts *p = proc_mounts(m); - return seq_list_next(v, &p->ns->list, pos); + p->cached_mount = seq_list_next(v, &p->ns->list, pos); + p->cached_index = *pos; + return p->cached_mount; } static void m_stop(struct seq_file *m, void *v) @@ -1085,12 +1156,12 @@ int may_umount_tree(struct vfsmount *m) BUG_ON(!m); /* write lock needed for mnt_get_count */ - br_write_lock(&vfsmount_lock); + lock_mount_hash(); for (p = mnt; p; p = next_mnt(p, mnt)) { actual_refs += mnt_get_count(p); minimum_refs += 2; } - br_write_unlock(&vfsmount_lock); + unlock_mount_hash(); if (actual_refs > minimum_refs) return 0; @@ -1117,48 +1188,40 @@ int may_umount(struct vfsmount *mnt) { int ret = 1; down_read(&namespace_sem); - br_write_lock(&vfsmount_lock); + lock_mount_hash(); if (propagate_mount_busy(real_mount(mnt), 2)) ret = 0; - br_write_unlock(&vfsmount_lock); + unlock_mount_hash(); up_read(&namespace_sem); return ret; } EXPORT_SYMBOL(may_umount); -static LIST_HEAD(unmounted); /* protected by namespace_sem */ +static HLIST_HEAD(unmounted); /* protected by namespace_sem */ static void namespace_unlock(void) { struct mount *mnt; - LIST_HEAD(head); + struct hlist_head head = unmounted; - if (likely(list_empty(&unmounted))) { + if (likely(hlist_empty(&head))) { up_write(&namespace_sem); return; } - list_splice_init(&unmounted, &head); + head.first->pprev = &head.first; + INIT_HLIST_HEAD(&unmounted); + up_write(&namespace_sem); - while (!list_empty(&head)) { - mnt = list_first_entry(&head, struct mount, mnt_hash); - list_del_init(&mnt->mnt_hash); - if (mnt_has_parent(mnt)) { - struct dentry *dentry; - struct mount *m; - - br_write_lock(&vfsmount_lock); - dentry = mnt->mnt_mountpoint; - m = mnt->mnt_parent; - mnt->mnt_mountpoint = mnt->mnt.mnt_root; - mnt->mnt_parent = mnt; - m->mnt_ghosts--; - br_write_unlock(&vfsmount_lock); - dput(dentry); - mntput(&m->mnt); - } + synchronize_rcu(); + + while (!hlist_empty(&head)) { + mnt = hlist_entry(head.first, struct mount, mnt_hash); + hlist_del_init(&mnt->mnt_hash); + if (mnt->mnt_ex_mountpoint.mnt) + path_put(&mnt->mnt_ex_mountpoint); mntput(&mnt->mnt); } } @@ -1169,34 +1232,51 @@ static inline void namespace_lock(void) } /* - * vfsmount lock must be held for write + * mount_lock must be held * namespace_sem must be held for write + * how = 0 => just this tree, don't propagate + * how = 1 => propagate; we know that nobody else has reference to any victims + * how = 2 => lazy umount */ -void umount_tree(struct mount *mnt, int propagate) +void umount_tree(struct mount *mnt, int how) { - LIST_HEAD(tmp_list); + HLIST_HEAD(tmp_list); struct mount *p; + struct mount *last = NULL; - for (p = mnt; p; p = next_mnt(p, mnt)) - list_move(&p->mnt_hash, &tmp_list); + for (p = mnt; p; p = next_mnt(p, mnt)) { + hlist_del_init_rcu(&p->mnt_hash); + hlist_add_head(&p->mnt_hash, &tmp_list); + } - if (propagate) + if (how) propagate_umount(&tmp_list); - list_for_each_entry(p, &tmp_list, mnt_hash) { + hlist_for_each_entry(p, &tmp_list, mnt_hash) { list_del_init(&p->mnt_expire); list_del_init(&p->mnt_list); __touch_mnt_namespace(p->mnt_ns); p->mnt_ns = NULL; + if (how < 2) + p->mnt.mnt_flags |= MNT_SYNC_UMOUNT; list_del_init(&p->mnt_child); if (mnt_has_parent(p)) { - p->mnt_parent->mnt_ghosts++; put_mountpoint(p->mnt_mp); + /* move the reference to mountpoint into ->mnt_ex_mountpoint */ + p->mnt_ex_mountpoint.dentry = p->mnt_mountpoint; + p->mnt_ex_mountpoint.mnt = &p->mnt_parent->mnt; + p->mnt_mountpoint = p->mnt.mnt_root; + p->mnt_parent = p; p->mnt_mp = NULL; } change_mnt_propagation(p, MS_PRIVATE); + last = p; + } + if (last) { + last->mnt_hash.next = unmounted.first; + unmounted.first = tmp_list.first; + unmounted.first->pprev = &unmounted.first; } - list_splice(&tmp_list, &unmounted); } static void shrink_submounts(struct mount *mnt); @@ -1225,12 +1305,12 @@ static int do_umount(struct mount *mnt, int flags) * probably don't strictly need the lock here if we examined * all race cases, but it's a slowpath. */ - br_write_lock(&vfsmount_lock); + lock_mount_hash(); if (mnt_get_count(mnt) != 2) { - br_write_unlock(&vfsmount_lock); + unlock_mount_hash(); return -EBUSY; } - br_write_unlock(&vfsmount_lock); + unlock_mount_hash(); if (!xchg(&mnt->mnt_expiry_mark, 1)) return -EAGAIN; @@ -1272,19 +1352,23 @@ static int do_umount(struct mount *mnt, int flags) } namespace_lock(); - br_write_lock(&vfsmount_lock); + lock_mount_hash(); event++; - if (!(flags & MNT_DETACH)) - shrink_submounts(mnt); - - retval = -EBUSY; - if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) { + if (flags & MNT_DETACH) { if (!list_empty(&mnt->mnt_list)) - umount_tree(mnt, 1); + umount_tree(mnt, 2); retval = 0; + } else { + shrink_submounts(mnt); + retval = -EBUSY; + if (!propagate_mount_busy(mnt, 2)) { + if (!list_empty(&mnt->mnt_list)) + umount_tree(mnt, 1); + retval = 0; + } } - br_write_unlock(&vfsmount_lock); + unlock_mount_hash(); namespace_unlock(); return retval; } @@ -1427,18 +1511,18 @@ struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, q = clone_mnt(p, p->mnt.mnt_root, flag); if (IS_ERR(q)) goto out; - br_write_lock(&vfsmount_lock); + lock_mount_hash(); list_add_tail(&q->mnt_list, &res->mnt_list); attach_mnt(q, parent, p->mnt_mp); - br_write_unlock(&vfsmount_lock); + unlock_mount_hash(); } } return res; out: if (res) { - br_write_lock(&vfsmount_lock); + lock_mount_hash(); umount_tree(res, 0); - br_write_unlock(&vfsmount_lock); + unlock_mount_hash(); } return q; } @@ -1460,9 +1544,9 @@ struct vfsmount *collect_mounts(struct path *path) void drop_collected_mounts(struct vfsmount *mnt) { namespace_lock(); - br_write_lock(&vfsmount_lock); + lock_mount_hash(); umount_tree(real_mount(mnt), 0); - br_write_unlock(&vfsmount_lock); + unlock_mount_hash(); namespace_unlock(); } @@ -1576,24 +1660,23 @@ static int attach_recursive_mnt(struct mount *source_mnt, struct mountpoint *dest_mp, struct path *parent_path) { - LIST_HEAD(tree_list); + HLIST_HEAD(tree_list); struct mount *child, *p; + struct hlist_node *n; int err; if (IS_MNT_SHARED(dest_mnt)) { err = invent_group_ids(source_mnt, true); if (err) goto out; - } - err = propagate_mnt(dest_mnt, dest_mp, source_mnt, &tree_list); - if (err) - goto out_cleanup_ids; - - br_write_lock(&vfsmount_lock); - - if (IS_MNT_SHARED(dest_mnt)) { + err = propagate_mnt(dest_mnt, dest_mp, source_mnt, &tree_list); + lock_mount_hash(); + if (err) + goto out_cleanup_ids; for (p = source_mnt; p; p = next_mnt(p, source_mnt)) set_mnt_shared(p); + } else { + lock_mount_hash(); } if (parent_path) { detach_mnt(source_mnt, parent_path); @@ -1601,20 +1684,27 @@ static int attach_recursive_mnt(struct mount *source_mnt, touch_mnt_namespace(source_mnt->mnt_ns); } else { mnt_set_mountpoint(dest_mnt, dest_mp, source_mnt); - commit_tree(source_mnt); + commit_tree(source_mnt, NULL); } - list_for_each_entry_safe(child, p, &tree_list, mnt_hash) { - list_del_init(&child->mnt_hash); - commit_tree(child); + hlist_for_each_entry_safe(child, n, &tree_list, mnt_hash) { + struct mount *q; + hlist_del_init(&child->mnt_hash); + q = __lookup_mnt_last(&child->mnt_parent->mnt, + child->mnt_mountpoint); + commit_tree(child, q); } - br_write_unlock(&vfsmount_lock); + unlock_mount_hash(); return 0; out_cleanup_ids: - if (IS_MNT_SHARED(dest_mnt)) - cleanup_group_ids(source_mnt, NULL); + while (!hlist_empty(&tree_list)) { + child = hlist_entry(tree_list.first, struct mount, mnt_hash); + umount_tree(child, 0); + } + unlock_mount_hash(); + cleanup_group_ids(source_mnt, NULL); out: return err; } @@ -1710,10 +1800,10 @@ static int do_change_type(struct path *path, int flag) goto out_unlock; } - br_write_lock(&vfsmount_lock); + lock_mount_hash(); for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) change_mnt_propagation(m, type); - br_write_unlock(&vfsmount_lock); + unlock_mount_hash(); out_unlock: namespace_unlock(); @@ -1785,9 +1875,9 @@ static int do_loopback(struct path *path, const char *old_name, err = graft_tree(mnt, parent, mp); if (err) { - br_write_lock(&vfsmount_lock); + lock_mount_hash(); umount_tree(mnt, 0); - br_write_unlock(&vfsmount_lock); + unlock_mount_hash(); } out2: unlock_mount(mp); @@ -1846,17 +1936,13 @@ static int do_remount(struct path *path, int flags, int mnt_flags, else err = do_remount_sb(sb, flags, data, 0); if (!err) { - br_write_lock(&vfsmount_lock); + lock_mount_hash(); mnt_flags |= mnt->mnt.mnt_flags & MNT_PROPAGATION_MASK; mnt->mnt.mnt_flags = mnt_flags; - br_write_unlock(&vfsmount_lock); - } - up_write(&sb->s_umount); - if (!err) { - br_write_lock(&vfsmount_lock); touch_mnt_namespace(mnt->mnt_ns); - br_write_unlock(&vfsmount_lock); + unlock_mount_hash(); } + up_write(&sb->s_umount); return err; } @@ -1972,7 +2058,7 @@ static int do_add_mount(struct mount *newmnt, struct path *path, int mnt_flags) struct mount *parent; int err; - mnt_flags &= ~(MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL); + mnt_flags &= ~MNT_INTERNAL_FLAGS; mp = lock_mount(path); if (IS_ERR(mp)) @@ -2077,9 +2163,7 @@ fail: /* remove m from any expiration list it may be on */ if (!list_empty(&mnt->mnt_expire)) { namespace_lock(); - br_write_lock(&vfsmount_lock); list_del_init(&mnt->mnt_expire); - br_write_unlock(&vfsmount_lock); namespace_unlock(); } mntput(m); @@ -2095,11 +2179,9 @@ fail: void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list) { namespace_lock(); - br_write_lock(&vfsmount_lock); list_add_tail(&real_mount(mnt)->mnt_expire, expiry_list); - br_write_unlock(&vfsmount_lock); namespace_unlock(); } EXPORT_SYMBOL(mnt_set_expiry); @@ -2118,7 +2200,7 @@ void mark_mounts_for_expiry(struct list_head *mounts) return; namespace_lock(); - br_write_lock(&vfsmount_lock); + lock_mount_hash(); /* extract from the expiration list every vfsmount that matches the * following criteria: @@ -2137,7 +2219,7 @@ void mark_mounts_for_expiry(struct list_head *mounts) touch_mnt_namespace(mnt->mnt_ns); umount_tree(mnt, 1); } - br_write_unlock(&vfsmount_lock); + unlock_mount_hash(); namespace_unlock(); } @@ -2193,7 +2275,7 @@ resume: * process a list of expirable mountpoints with the intent of discarding any * submounts of a specific parent mountpoint * - * vfsmount_lock must be held for write + * mount_lock must be held for write */ static void shrink_submounts(struct mount *mnt) { @@ -2414,20 +2496,25 @@ static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns) return new_ns; } -/* - * Allocate a new namespace structure and populate it with contents - * copied from the namespace of the passed in task structure. - */ -static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns, - struct user_namespace *user_ns, struct fs_struct *fs) +struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns, + struct user_namespace *user_ns, struct fs_struct *new_fs) { struct mnt_namespace *new_ns; struct vfsmount *rootmnt = NULL, *pwdmnt = NULL; struct mount *p, *q; - struct mount *old = mnt_ns->root; + struct mount *old; struct mount *new; int copy_flags; + BUG_ON(!ns); + + if (likely(!(flags & CLONE_NEWNS))) { + get_mnt_ns(ns); + return ns; + } + + old = ns->root; + new_ns = alloc_mnt_ns(user_ns); if (IS_ERR(new_ns)) return new_ns; @@ -2435,7 +2522,7 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns, namespace_lock(); /* First pass: copy the tree topology */ copy_flags = CL_COPY_UNBINDABLE | CL_EXPIRE; - if (user_ns != mnt_ns->user_ns) + if (user_ns != ns->user_ns) copy_flags |= CL_SHARED_TO_SLAVE | CL_UNPRIVILEGED; new = copy_tree(old, old->mnt.mnt_root, copy_flags); if (IS_ERR(new)) { @@ -2444,9 +2531,7 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns, return ERR_CAST(new); } new_ns->root = new; - br_write_lock(&vfsmount_lock); list_add_tail(&new_ns->list, &new->mnt_list); - br_write_unlock(&vfsmount_lock); /* * Second pass: switch the tsk->fs->* elements and mark new vfsmounts @@ -2457,13 +2542,13 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns, q = new; while (p) { q->mnt_ns = new_ns; - if (fs) { - if (&p->mnt == fs->root.mnt) { - fs->root.mnt = mntget(&q->mnt); + if (new_fs) { + if (&p->mnt == new_fs->root.mnt) { + new_fs->root.mnt = mntget(&q->mnt); rootmnt = &p->mnt; } - if (&p->mnt == fs->pwd.mnt) { - fs->pwd.mnt = mntget(&q->mnt); + if (&p->mnt == new_fs->pwd.mnt) { + new_fs->pwd.mnt = mntget(&q->mnt); pwdmnt = &p->mnt; } } @@ -2484,23 +2569,6 @@ static struct mnt_namespace *dup_mnt_ns(struct mnt_namespace *mnt_ns, return new_ns; } -struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns, - struct user_namespace *user_ns, struct fs_struct *new_fs) -{ - struct mnt_namespace *new_ns; - - BUG_ON(!ns); - get_mnt_ns(ns); - - if (!(flags & CLONE_NEWNS)) - return ns; - - new_ns = dup_mnt_ns(ns, user_ns, new_fs); - - put_mnt_ns(ns); - return new_ns; -} - /** * create_mnt_ns - creates a private namespace and adds a root filesystem * @mnt: pointer to the new root filesystem mountpoint @@ -2593,7 +2661,7 @@ out_type: /* * Return true if path is reachable from root * - * namespace_sem or vfsmount_lock is held + * namespace_sem or mount_lock is held */ bool is_path_reachable(struct mount *mnt, struct dentry *dentry, const struct path *root) @@ -2608,9 +2676,9 @@ bool is_path_reachable(struct mount *mnt, struct dentry *dentry, int path_is_under(struct path *path1, struct path *path2) { int res; - br_read_lock(&vfsmount_lock); + read_seqlock_excl(&mount_lock); res = is_path_reachable(real_mount(path1->mnt), path1->dentry, path2); - br_read_unlock(&vfsmount_lock); + read_sequnlock_excl(&mount_lock); return res; } EXPORT_SYMBOL(path_is_under); @@ -2701,7 +2769,7 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, if (!is_path_reachable(old_mnt, old.dentry, &new)) goto out4; root_mp->m_count++; /* pin it so it won't go away */ - br_write_lock(&vfsmount_lock); + lock_mount_hash(); detach_mnt(new_mnt, &parent_path); detach_mnt(root_mnt, &root_parent); if (root_mnt->mnt.mnt_flags & MNT_LOCKED) { @@ -2713,7 +2781,7 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, /* mount new_root on / */ attach_mnt(new_mnt, real_mount(root_parent.mnt), root_mp); touch_mnt_namespace(current->nsproxy->mnt_ns); - br_write_unlock(&vfsmount_lock); + unlock_mount_hash(); chroot_fs_refs(&root, &new); put_mountpoint(root_mp); error = 0; @@ -2767,25 +2835,29 @@ void __init mnt_init(void) unsigned u; int err; - init_rwsem(&namespace_sem); - mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct mount), 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL); - mount_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC); - mountpoint_hashtable = (struct list_head *)__get_free_page(GFP_ATOMIC); + mount_hashtable = alloc_large_system_hash("Mount-cache", + sizeof(struct hlist_head), + mhash_entries, 19, + 0, + &m_hash_shift, &m_hash_mask, 0, 0); + mountpoint_hashtable = alloc_large_system_hash("Mountpoint-cache", + sizeof(struct hlist_head), + mphash_entries, 19, + 0, + &mp_hash_shift, &mp_hash_mask, 0, 0); if (!mount_hashtable || !mountpoint_hashtable) panic("Failed to allocate mount hash table\n"); - printk(KERN_INFO "Mount-cache hash table entries: %lu\n", HASH_SIZE); - - for (u = 0; u < HASH_SIZE; u++) - INIT_LIST_HEAD(&mount_hashtable[u]); - for (u = 0; u < HASH_SIZE; u++) - INIT_LIST_HEAD(&mountpoint_hashtable[u]); + for (u = 0; u <= m_hash_mask; u++) + INIT_HLIST_HEAD(&mount_hashtable[u]); + for (u = 0; u <= mp_hash_mask; u++) + INIT_HLIST_HEAD(&mountpoint_hashtable[u]); - br_lock_init(&vfsmount_lock); + kernfs_init(); err = sysfs_init(); if (err) @@ -2802,11 +2874,7 @@ void put_mnt_ns(struct mnt_namespace *ns) { if (!atomic_dec_and_test(&ns->count)) return; - namespace_lock(); - br_write_lock(&vfsmount_lock); - umount_tree(ns->root, 0); - br_write_unlock(&vfsmount_lock); - namespace_unlock(); + drop_collected_mounts(&ns->root->mnt); free_mnt_ns(ns); } @@ -2829,9 +2897,8 @@ void kern_unmount(struct vfsmount *mnt) { /* release long term mount so mount point can be released */ if (!IS_ERR_OR_NULL(mnt)) { - br_write_lock(&vfsmount_lock); real_mount(mnt)->mnt_ns = NULL; - br_write_unlock(&vfsmount_lock); + synchronize_rcu(); /* yecchhh... */ mntput(mnt); } } @@ -2875,7 +2942,7 @@ bool fs_fully_visible(struct file_system_type *type) if (unlikely(!ns)) return false; - namespace_lock(); + down_read(&namespace_sem); list_for_each_entry(mnt, &ns->list, mnt_list) { struct mount *child; if (mnt->mnt.mnt_sb->s_type != type) @@ -2888,7 +2955,7 @@ bool fs_fully_visible(struct file_system_type *type) struct inode *inode = child->mnt_mountpoint->d_inode; if (!S_ISDIR(inode->i_mode)) goto next; - if (inode->i_nlink != 2) + if (inode->i_nlink > 2) goto next; } visible = true; @@ -2896,7 +2963,7 @@ bool fs_fully_visible(struct file_system_type *type) next: ; } found: - namespace_unlock(); + up_read(&namespace_sem); return visible; } |