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-rw-r--r--fs/dcache.c25
-rw-r--r--fs/namei.c22
-rw-r--r--fs/namespace.c64
-rw-r--r--fs/proc/base.c9
-rw-r--r--include/linux/mount.h1
5 files changed, 68 insertions, 53 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index c7572104823f..6c7e6bf18467 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1451,19 +1451,24 @@ out:
int is_subdir(struct dentry * new_dentry, struct dentry * old_dentry)
{
int result;
+ unsigned long seq;
result = 0;
- for (;;) {
- if (new_dentry != old_dentry) {
- struct dentry * parent = new_dentry->d_parent;
- if (parent == new_dentry)
- break;
- new_dentry = parent;
- continue;
+ do {
+ seq = read_seqbegin(&rename_lock);
+ for (;;) {
+ if (new_dentry != old_dentry) {
+ struct dentry * parent = new_dentry->d_parent;
+ if (parent == new_dentry)
+ break;
+ new_dentry = parent;
+ continue;
+ }
+ result = 1;
+ break;
}
- result = 1;
- break;
- }
+ } while (read_seqretry(&rename_lock, seq));
+
return result;
}
diff --git a/fs/namei.c b/fs/namei.c
index 4bd15bdcef47..8810138eaaec 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -434,19 +434,17 @@ int follow_up(struct vfsmount **mnt, struct dentry **dentry)
return 1;
}
+/* no need for dcache_lock, as serialization is taken care in
+ * namespace.c
+ */
static int follow_mount(struct vfsmount **mnt, struct dentry **dentry)
{
int res = 0;
while (d_mountpoint(*dentry)) {
- struct vfsmount *mounted;
- spin_lock(&dcache_lock);
- mounted = lookup_mnt(*mnt, *dentry);
- if (!mounted) {
- spin_unlock(&dcache_lock);
+ struct vfsmount *mounted = lookup_mnt(*mnt, *dentry);
+ if (!mounted)
break;
- }
- *mnt = mntget(mounted);
- spin_unlock(&dcache_lock);
+ *mnt = mounted;
dput(*dentry);
mntput(mounted->mnt_parent);
*dentry = dget(mounted->mnt_root);
@@ -455,21 +453,21 @@ static int follow_mount(struct vfsmount **mnt, struct dentry **dentry)
return res;
}
+/* no need for dcache_lock, as serialization is taken care in
+ * namespace.c
+ */
static inline int __follow_down(struct vfsmount **mnt, struct dentry **dentry)
{
struct vfsmount *mounted;
- spin_lock(&dcache_lock);
mounted = lookup_mnt(*mnt, *dentry);
if (mounted) {
- *mnt = mntget(mounted);
- spin_unlock(&dcache_lock);
+ *mnt = mounted;
dput(*dentry);
mntput(mounted->mnt_parent);
*dentry = dget(mounted->mnt_root);
return 1;
}
- spin_unlock(&dcache_lock);
return 0;
}
diff --git a/fs/namespace.c b/fs/namespace.c
index a31cd95801cb..12a8c8146829 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -26,6 +26,8 @@
extern int __init init_rootfs(void);
extern int __init sysfs_init(void);
+/* spinlock for vfsmount related operations, inplace of dcache_lock */
+spinlock_t vfsmount_lock __cacheline_aligned_in_smp = SPIN_LOCK_UNLOCKED;
static struct list_head *mount_hashtable;
static int hash_mask, hash_bits;
static kmem_cache_t *mnt_cache;
@@ -66,30 +68,38 @@ void free_vfsmnt(struct vfsmount *mnt)
kmem_cache_free(mnt_cache, mnt);
}
+/*
+ * Now, lookup_mnt increments the ref count before returning
+ * the vfsmount struct.
+ */
struct vfsmount *lookup_mnt(struct vfsmount *mnt, struct dentry *dentry)
{
struct list_head * head = mount_hashtable + hash(mnt, dentry);
struct list_head * tmp = head;
- struct vfsmount *p;
+ struct vfsmount *p, *found = NULL;
+ spin_lock(&vfsmount_lock);
for (;;) {
tmp = tmp->next;
p = NULL;
if (tmp == head)
break;
p = list_entry(tmp, struct vfsmount, mnt_hash);
- if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry)
+ if (p->mnt_parent == mnt && p->mnt_mountpoint == dentry) {
+ found = mntget(p);
break;
+ }
}
- return p;
+ spin_unlock(&vfsmount_lock);
+ return found;
}
static int check_mnt(struct vfsmount *mnt)
{
- spin_lock(&dcache_lock);
+ spin_lock(&vfsmount_lock);
while (mnt->mnt_parent != mnt)
mnt = mnt->mnt_parent;
- spin_unlock(&dcache_lock);
+ spin_unlock(&vfsmount_lock);
return mnt == current->namespace->root;
}
@@ -263,15 +273,15 @@ void umount_tree(struct vfsmount *mnt)
mnt = list_entry(kill.next, struct vfsmount, mnt_list);
list_del_init(&mnt->mnt_list);
if (mnt->mnt_parent == mnt) {
- spin_unlock(&dcache_lock);
+ spin_unlock(&vfsmount_lock);
} else {
struct nameidata old_nd;
detach_mnt(mnt, &old_nd);
- spin_unlock(&dcache_lock);
+ spin_unlock(&vfsmount_lock);
path_release(&old_nd);
}
mntput(mnt);
- spin_lock(&dcache_lock);
+ spin_lock(&vfsmount_lock);
}
}
@@ -324,17 +334,17 @@ static int do_umount(struct vfsmount *mnt, int flags)
}
down_write(&current->namespace->sem);
- spin_lock(&dcache_lock);
+ spin_lock(&vfsmount_lock);
if (atomic_read(&sb->s_active) == 1) {
/* last instance - try to be smart */
- spin_unlock(&dcache_lock);
+ spin_unlock(&vfsmount_lock);
lock_kernel();
DQUOT_OFF(sb);
acct_auto_close(sb);
unlock_kernel();
security_sb_umount_close(mnt);
- spin_lock(&dcache_lock);
+ spin_lock(&vfsmount_lock);
}
retval = -EBUSY;
if (atomic_read(&mnt->mnt_count) == 2 || flags & MNT_DETACH) {
@@ -342,7 +352,7 @@ static int do_umount(struct vfsmount *mnt, int flags)
umount_tree(mnt);
retval = 0;
}
- spin_unlock(&dcache_lock);
+ spin_unlock(&vfsmount_lock);
if (retval)
security_sb_umount_busy(mnt);
up_write(&current->namespace->sem);
@@ -449,18 +459,18 @@ static struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry)
q = clone_mnt(p, p->mnt_root);
if (!q)
goto Enomem;
- spin_lock(&dcache_lock);
+ spin_lock(&vfsmount_lock);
list_add_tail(&q->mnt_list, &res->mnt_list);
attach_mnt(q, &nd);
- spin_unlock(&dcache_lock);
+ spin_unlock(&vfsmount_lock);
}
}
return res;
Enomem:
if (res) {
- spin_lock(&dcache_lock);
+ spin_lock(&vfsmount_lock);
umount_tree(res);
- spin_unlock(&dcache_lock);
+ spin_unlock(&vfsmount_lock);
}
return NULL;
}
@@ -485,7 +495,7 @@ static int graft_tree(struct vfsmount *mnt, struct nameidata *nd)
goto out_unlock;
err = -ENOENT;
- spin_lock(&dcache_lock);
+ spin_lock(&vfsmount_lock);
if (IS_ROOT(nd->dentry) || !d_unhashed(nd->dentry)) {
struct list_head head;
@@ -495,7 +505,7 @@ static int graft_tree(struct vfsmount *mnt, struct nameidata *nd)
mntget(mnt);
err = 0;
}
- spin_unlock(&dcache_lock);
+ spin_unlock(&vfsmount_lock);
out_unlock:
up(&nd->dentry->d_inode->i_sem);
if (!err)
@@ -532,9 +542,9 @@ static int do_loopback(struct nameidata *nd, char *old_name, int recurse)
if (mnt) {
err = graft_tree(mnt, nd);
if (err) {
- spin_lock(&dcache_lock);
+ spin_lock(&vfsmount_lock);
umount_tree(mnt);
- spin_unlock(&dcache_lock);
+ spin_unlock(&vfsmount_lock);
} else
mntput(mnt);
}
@@ -599,7 +609,7 @@ static int do_move_mount(struct nameidata *nd, char *old_name)
if (IS_DEADDIR(nd->dentry->d_inode))
goto out1;
- spin_lock(&dcache_lock);
+ spin_lock(&vfsmount_lock);
if (!IS_ROOT(nd->dentry) && d_unhashed(nd->dentry))
goto out2;
@@ -623,7 +633,7 @@ static int do_move_mount(struct nameidata *nd, char *old_name)
detach_mnt(old_nd.mnt, &parent_nd);
attach_mnt(old_nd.mnt, nd);
out2:
- spin_unlock(&dcache_lock);
+ spin_unlock(&vfsmount_lock);
out1:
up(&nd->dentry->d_inode->i_sem);
out:
@@ -804,9 +814,9 @@ int copy_namespace(int flags, struct task_struct *tsk)
down_write(&tsk->namespace->sem);
/* First pass: copy the tree topology */
new_ns->root = copy_tree(namespace->root, namespace->root->mnt_root);
- spin_lock(&dcache_lock);
+ spin_lock(&vfsmount_lock);
list_add_tail(&new_ns->list, &new_ns->root->mnt_list);
- spin_unlock(&dcache_lock);
+ spin_unlock(&vfsmount_lock);
/* Second pass: switch the tsk->fs->* elements */
if (fs) {
@@ -1027,7 +1037,7 @@ asmlinkage long sys_pivot_root(const char __user *new_root, const char __user *p
if (new_nd.mnt->mnt_root != new_nd.dentry)
goto out2; /* not a mountpoint */
tmp = old_nd.mnt; /* make sure we can reach put_old from new_root */
- spin_lock(&dcache_lock);
+ spin_lock(&vfsmount_lock);
if (tmp != new_nd.mnt) {
for (;;) {
if (tmp->mnt_parent == tmp)
@@ -1044,7 +1054,7 @@ asmlinkage long sys_pivot_root(const char __user *new_root, const char __user *p
detach_mnt(user_nd.mnt, &root_parent);
attach_mnt(user_nd.mnt, &old_nd);
attach_mnt(new_nd.mnt, &root_parent);
- spin_unlock(&dcache_lock);
+ spin_unlock(&vfsmount_lock);
chroot_fs_refs(&user_nd, &new_nd);
security_sb_post_pivotroot(&user_nd, &new_nd);
error = 0;
@@ -1061,7 +1071,7 @@ out0:
unlock_kernel();
return error;
out3:
- spin_unlock(&dcache_lock);
+ spin_unlock(&vfsmount_lock);
goto out2;
}
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 485ff692e87f..0a061cd0bb6f 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -307,20 +307,22 @@ static int proc_check_root(struct inode *inode)
base = dget(current->fs->root);
read_unlock(&current->fs->lock);
- spin_lock(&dcache_lock);
+ spin_lock(&vfsmount_lock);
de = root;
mnt = vfsmnt;
while (vfsmnt != our_vfsmnt) {
- if (vfsmnt == vfsmnt->mnt_parent)
+ if (vfsmnt == vfsmnt->mnt_parent) {
+ spin_unlock(&vfsmount_lock);
goto out;
+ }
de = vfsmnt->mnt_mountpoint;
vfsmnt = vfsmnt->mnt_parent;
}
+ spin_unlock(&vfsmount_lock);
if (!is_subdir(de, base))
goto out;
- spin_unlock(&dcache_lock);
exit:
dput(base);
@@ -329,7 +331,6 @@ exit:
mntput(mnt);
return res;
out:
- spin_unlock(&dcache_lock);
res = -EACCES;
goto exit;
}
diff --git a/include/linux/mount.h b/include/linux/mount.h
index d6996e7c7310..61554dda78a8 100644
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -54,6 +54,7 @@ extern void free_vfsmnt(struct vfsmount *mnt);
extern struct vfsmount *alloc_vfsmnt(const char *name);
extern struct vfsmount *do_kern_mount(const char *fstype, int flags,
const char *name, void *data);
+extern spinlock_t vfsmount_lock;
#endif
#endif /* _LINUX_MOUNT_H */
generated by cgit v1.2.3 (git 2.46.0) at 2026-01-31 21:07:35 +0000