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Diffstat (limited to 'fs/namei.c')
-rw-r--r--fs/namei.c174
1 files changed, 105 insertions, 69 deletions
diff --git a/fs/namei.c b/fs/namei.c
index defe6781e00..fa8df81ce8c 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -493,12 +493,21 @@ fail:
return PTR_ERR(link);
}
-static inline int __do_follow_link(struct dentry *dentry, struct nameidata *nd)
+struct path {
+ struct vfsmount *mnt;
+ struct dentry *dentry;
+};
+
+static inline int __do_follow_link(struct path *path, struct nameidata *nd)
{
int error;
+ struct dentry *dentry = path->dentry;
- touch_atime(nd->mnt, dentry);
+ touch_atime(path->mnt, dentry);
nd_set_link(nd, NULL);
+
+ if (path->mnt == nd->mnt)
+ mntget(path->mnt);
error = dentry->d_inode->i_op->follow_link(dentry, nd);
if (!error) {
char *s = nd_get_link(nd);
@@ -507,6 +516,8 @@ static inline int __do_follow_link(struct dentry *dentry, struct nameidata *nd)
if (dentry->d_inode->i_op->put_link)
dentry->d_inode->i_op->put_link(dentry, nd);
}
+ dput(dentry);
+ mntput(path->mnt);
return error;
}
@@ -518,7 +529,7 @@ static inline int __do_follow_link(struct dentry *dentry, struct nameidata *nd)
* Without that kind of total limit, nasty chains of consecutive
* symlinks can cause almost arbitrarily long lookups.
*/
-static inline int do_follow_link(struct dentry *dentry, struct nameidata *nd)
+static inline int do_follow_link(struct path *path, struct nameidata *nd)
{
int err = -ELOOP;
if (current->link_count >= MAX_NESTED_LINKS)
@@ -527,17 +538,20 @@ static inline int do_follow_link(struct dentry *dentry, struct nameidata *nd)
goto loop;
BUG_ON(nd->depth >= MAX_NESTED_LINKS);
cond_resched();
- err = security_inode_follow_link(dentry, nd);
+ err = security_inode_follow_link(path->dentry, nd);
if (err)
goto loop;
current->link_count++;
current->total_link_count++;
nd->depth++;
- err = __do_follow_link(dentry, nd);
+ err = __do_follow_link(path, nd);
current->link_count--;
nd->depth--;
return err;
loop:
+ dput(path->dentry);
+ if (path->mnt != nd->mnt)
+ mntput(path->mnt);
path_release(nd);
return err;
}
@@ -565,87 +579,91 @@ int follow_up(struct vfsmount **mnt, struct dentry **dentry)
/* no need for dcache_lock, as serialization is taken care in
* namespace.c
*/
-static int follow_mount(struct vfsmount **mnt, struct dentry **dentry)
+static int __follow_mount(struct path *path)
{
int res = 0;
+ while (d_mountpoint(path->dentry)) {
+ struct vfsmount *mounted = lookup_mnt(path->mnt, path->dentry);
+ if (!mounted)
+ break;
+ dput(path->dentry);
+ if (res)
+ mntput(path->mnt);
+ path->mnt = mounted;
+ path->dentry = dget(mounted->mnt_root);
+ res = 1;
+ }
+ return res;
+}
+
+static void follow_mount(struct vfsmount **mnt, struct dentry **dentry)
+{
while (d_mountpoint(*dentry)) {
struct vfsmount *mounted = lookup_mnt(*mnt, *dentry);
if (!mounted)
break;
+ dput(*dentry);
mntput(*mnt);
*mnt = mounted;
- dput(*dentry);
*dentry = dget(mounted->mnt_root);
- res = 1;
}
- 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)
+int follow_down(struct vfsmount **mnt, struct dentry **dentry)
{
struct vfsmount *mounted;
mounted = lookup_mnt(*mnt, *dentry);
if (mounted) {
+ dput(*dentry);
mntput(*mnt);
*mnt = mounted;
- dput(*dentry);
*dentry = dget(mounted->mnt_root);
return 1;
}
return 0;
}
-int follow_down(struct vfsmount **mnt, struct dentry **dentry)
-{
- return __follow_down(mnt,dentry);
-}
-
-static inline void follow_dotdot(struct vfsmount **mnt, struct dentry **dentry)
+static inline void follow_dotdot(struct nameidata *nd)
{
while(1) {
struct vfsmount *parent;
- struct dentry *old = *dentry;
+ struct dentry *old = nd->dentry;
read_lock(&current->fs->lock);
- if (*dentry == current->fs->root &&
- *mnt == current->fs->rootmnt) {
+ if (nd->dentry == current->fs->root &&
+ nd->mnt == current->fs->rootmnt) {
read_unlock(&current->fs->lock);
break;
}
read_unlock(&current->fs->lock);
spin_lock(&dcache_lock);
- if (*dentry != (*mnt)->mnt_root) {
- *dentry = dget((*dentry)->d_parent);
+ if (nd->dentry != nd->mnt->mnt_root) {
+ nd->dentry = dget(nd->dentry->d_parent);
spin_unlock(&dcache_lock);
dput(old);
break;
}
spin_unlock(&dcache_lock);
spin_lock(&vfsmount_lock);
- parent = (*mnt)->mnt_parent;
- if (parent == *mnt) {
+ parent = nd->mnt->mnt_parent;
+ if (parent == nd->mnt) {
spin_unlock(&vfsmount_lock);
break;
}
mntget(parent);
- *dentry = dget((*mnt)->mnt_mountpoint);
+ nd->dentry = dget(nd->mnt->mnt_mountpoint);
spin_unlock(&vfsmount_lock);
dput(old);
- mntput(*mnt);
- *mnt = parent;
+ mntput(nd->mnt);
+ nd->mnt = parent;
}
- follow_mount(mnt, dentry);
+ follow_mount(&nd->mnt, &nd->dentry);
}
-struct path {
- struct vfsmount *mnt;
- struct dentry *dentry;
-};
-
/*
* It's more convoluted than I'd like it to be, but... it's still fairly
* small and for now I'd prefer to have fast path as straight as possible.
@@ -664,6 +682,7 @@ static int do_lookup(struct nameidata *nd, struct qstr *name,
done:
path->mnt = mnt;
path->dentry = dentry;
+ __follow_mount(path);
return 0;
need_lookup:
@@ -751,7 +770,7 @@ static fastcall int __link_path_walk(const char * name, struct nameidata *nd)
case 2:
if (this.name[1] != '.')
break;
- follow_dotdot(&nd->mnt, &nd->dentry);
+ follow_dotdot(nd);
inode = nd->dentry->d_inode;
/* fallthrough */
case 1:
@@ -771,8 +790,6 @@ static fastcall int __link_path_walk(const char * name, struct nameidata *nd)
err = do_lookup(nd, &this, &next);
if (err)
break;
- /* Check mountpoints.. */
- follow_mount(&next.mnt, &next.dentry);
err = -ENOENT;
inode = next.dentry->d_inode;
@@ -783,10 +800,7 @@ static fastcall int __link_path_walk(const char * name, struct nameidata *nd)
goto out_dput;
if (inode->i_op->follow_link) {
- mntget(next.mnt);
- err = do_follow_link(next.dentry, nd);
- dput(next.dentry);
- mntput(next.mnt);
+ err = do_follow_link(&next, nd);
if (err)
goto return_err;
err = -ENOENT;
@@ -798,6 +812,8 @@ static fastcall int __link_path_walk(const char * name, struct nameidata *nd)
break;
} else {
dput(nd->dentry);
+ if (nd->mnt != next.mnt)
+ mntput(nd->mnt);
nd->mnt = next.mnt;
nd->dentry = next.dentry;
}
@@ -819,7 +835,7 @@ last_component:
case 2:
if (this.name[1] != '.')
break;
- follow_dotdot(&nd->mnt, &nd->dentry);
+ follow_dotdot(nd);
inode = nd->dentry->d_inode;
/* fallthrough */
case 1:
@@ -833,19 +849,17 @@ last_component:
err = do_lookup(nd, &this, &next);
if (err)
break;
- follow_mount(&next.mnt, &next.dentry);
inode = next.dentry->d_inode;
if ((lookup_flags & LOOKUP_FOLLOW)
&& inode && inode->i_op && inode->i_op->follow_link) {
- mntget(next.mnt);
- err = do_follow_link(next.dentry, nd);
- dput(next.dentry);
- mntput(next.mnt);
+ err = do_follow_link(&next, nd);
if (err)
goto return_err;
inode = nd->dentry->d_inode;
} else {
dput(nd->dentry);
+ if (nd->mnt != next.mnt)
+ mntput(nd->mnt);
nd->mnt = next.mnt;
nd->dentry = next.dentry;
}
@@ -885,6 +899,8 @@ return_base:
return 0;
out_dput:
dput(next.dentry);
+ if (nd->mnt != next.mnt)
+ mntput(next.mnt);
break;
}
path_release(nd);
@@ -1398,7 +1414,7 @@ int may_open(struct nameidata *nd, int acc_mode, int flag)
int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd)
{
int acc_mode, error = 0;
- struct dentry *dentry;
+ struct path path;
struct dentry *dir;
int count = 0;
@@ -1442,23 +1458,24 @@ int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd)
dir = nd->dentry;
nd->flags &= ~LOOKUP_PARENT;
down(&dir->d_inode->i_sem);
- dentry = __lookup_hash(&nd->last, nd->dentry, nd);
+ path.dentry = __lookup_hash(&nd->last, nd->dentry, nd);
+ path.mnt = nd->mnt;
do_last:
- error = PTR_ERR(dentry);
- if (IS_ERR(dentry)) {
+ error = PTR_ERR(path.dentry);
+ if (IS_ERR(path.dentry)) {
up(&dir->d_inode->i_sem);
goto exit;
}
/* Negative dentry, just create the file */
- if (!dentry->d_inode) {
+ if (!path.dentry->d_inode) {
if (!IS_POSIXACL(dir->d_inode))
mode &= ~current->fs->umask;
- error = vfs_create(dir->d_inode, dentry, mode, nd);
+ error = vfs_create(dir->d_inode, path.dentry, mode, nd);
up(&dir->d_inode->i_sem);
dput(nd->dentry);
- nd->dentry = dentry;
+ nd->dentry = path.dentry;
if (error)
goto exit;
/* Don't check for write permission, don't truncate */
@@ -1476,22 +1493,24 @@ do_last:
if (flag & O_EXCL)
goto exit_dput;
- if (d_mountpoint(dentry)) {
+ if (__follow_mount(&path)) {
error = -ELOOP;
if (flag & O_NOFOLLOW)
goto exit_dput;
- while (__follow_down(&nd->mnt,&dentry) && d_mountpoint(dentry));
}
error = -ENOENT;
- if (!dentry->d_inode)
+ if (!path.dentry->d_inode)
goto exit_dput;
- if (dentry->d_inode->i_op && dentry->d_inode->i_op->follow_link)
+ if (path.dentry->d_inode->i_op && path.dentry->d_inode->i_op->follow_link)
goto do_link;
dput(nd->dentry);
- nd->dentry = dentry;
+ nd->dentry = path.dentry;
+ if (nd->mnt != path.mnt)
+ mntput(nd->mnt);
+ nd->mnt = path.mnt;
error = -EISDIR;
- if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode))
+ if (path.dentry->d_inode && S_ISDIR(path.dentry->d_inode->i_mode))
goto exit;
ok:
error = may_open(nd, acc_mode, flag);
@@ -1500,7 +1519,9 @@ ok:
return 0;
exit_dput:
- dput(dentry);
+ dput(path.dentry);
+ if (nd->mnt != path.mnt)
+ mntput(path.mnt);
exit:
path_release(nd);
return error;
@@ -1520,18 +1541,15 @@ do_link:
* are done. Procfs-like symlinks just set LAST_BIND.
*/
nd->flags |= LOOKUP_PARENT;
- error = security_inode_follow_link(dentry, nd);
+ error = security_inode_follow_link(path.dentry, nd);
if (error)
goto exit_dput;
- error = __do_follow_link(dentry, nd);
- dput(dentry);
+ error = __do_follow_link(&path, nd);
if (error)
return error;
nd->flags &= ~LOOKUP_PARENT;
- if (nd->last_type == LAST_BIND) {
- dentry = nd->dentry;
+ if (nd->last_type == LAST_BIND)
goto ok;
- }
error = -EISDIR;
if (nd->last_type != LAST_NORM)
goto exit;
@@ -1546,7 +1564,8 @@ do_link:
}
dir = nd->dentry;
down(&dir->d_inode->i_sem);
- dentry = __lookup_hash(&nd->last, nd->dentry, nd);
+ path.dentry = __lookup_hash(&nd->last, nd->dentry, nd);
+ path.mnt = nd->mnt;
putname(nd->last.name);
goto do_last;
}
@@ -1558,19 +1577,35 @@ do_link:
*
* Simple function to lookup and return a dentry and create it
* if it doesn't exist. Is SMP-safe.
+ *
+ * Returns with nd->dentry->d_inode->i_sem locked.
*/
struct dentry *lookup_create(struct nameidata *nd, int is_dir)
{
- struct dentry *dentry;
+ struct dentry *dentry = ERR_PTR(-EEXIST);
down(&nd->dentry->d_inode->i_sem);
- dentry = ERR_PTR(-EEXIST);
+ /*
+ * Yucky last component or no last component at all?
+ * (foo/., foo/.., /////)
+ */
if (nd->last_type != LAST_NORM)
goto fail;
nd->flags &= ~LOOKUP_PARENT;
+
+ /*
+ * Do the final lookup.
+ */
dentry = lookup_hash(&nd->last, nd->dentry);
if (IS_ERR(dentry))
goto fail;
+
+ /*
+ * Special case - lookup gave negative, but... we had foo/bar/
+ * From the vfs_mknod() POV we just have a negative dentry -
+ * all is fine. Let's be bastards - you had / on the end, you've
+ * been asking for (non-existent) directory. -ENOENT for you.
+ */
if (!is_dir && nd->last.name[nd->last.len] && !dentry->d_inode)
goto enoent;
return dentry;
@@ -1580,6 +1615,7 @@ enoent:
fail:
return dentry;
}
+EXPORT_SYMBOL_GPL(lookup_create);
int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
{
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-10 06:08:29 +0000