Get rid of path_lookup in autofs4
Al Viro [Tue, 7 Apr 2009 15:08:56 +0000 (11:08 -0400)]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/autofs4/dev-ioctl.c

index 84168c0..f71dac9 100644 (file)
@@ -192,77 +192,42 @@ static int autofs_dev_ioctl_protosubver(struct file *fp,
        return 0;
 }
 
-/*
- * Walk down the mount stack looking for an autofs mount that
- * has the requested device number (aka. new_encode_dev(sb->s_dev).
- */
-static int autofs_dev_ioctl_find_super(struct nameidata *nd, dev_t devno)
+static int find_autofs_mount(const char *pathname,
+                            struct path *res,
+                            int test(struct path *path, void *data),
+                            void *data)
 {
-       struct dentry *dentry;
-       struct inode *inode;
-       struct super_block *sb;
-       dev_t s_dev;
-       unsigned int err;
-
+       struct path path;
+       int err = kern_path(pathname, 0, &path);
+       if (err)
+               return err;
        err = -ENOENT;
-
-       /* Lookup the dentry name at the base of our mount point */
-       dentry = d_lookup(nd->path.dentry, &nd->last);
-       if (!dentry)
-               goto out;
-
-       dput(nd->path.dentry);
-       nd->path.dentry = dentry;
-
-       /* And follow the mount stack looking for our autofs mount */
-       while (follow_down(&nd->path.mnt, &nd->path.dentry)) {
-               inode = nd->path.dentry->d_inode;
-               if (!inode)
-                       break;
-
-               sb = inode->i_sb;
-               s_dev = new_encode_dev(sb->s_dev);
-               if (devno == s_dev) {
-                       if (sb->s_magic == AUTOFS_SUPER_MAGIC) {
+       while (path.dentry == path.mnt->mnt_root) {
+               if (path.mnt->mnt_sb->s_magic == AUTOFS_SUPER_MAGIC) {
+                       if (test(&path, data)) {
+                               path_get(&path);
+                               if (!err) /* already found some */
+                                       path_put(res);
+                               *res = path;
                                err = 0;
-                               break;
                        }
                }
+               if (!follow_up(&path.mnt, &path.dentry))
+                       break;
        }
-out:
+       path_put(&path);
        return err;
 }
 
-/*
- * Walk down the mount stack looking for an autofs mount that
- * has the requested mount type (ie. indirect, direct or offset).
- */
-static int autofs_dev_ioctl_find_sbi_type(struct nameidata *nd, unsigned int type)
+static int test_by_dev(struct path *path, void *p)
 {
-       struct dentry *dentry;
-       struct autofs_info *ino;
-       unsigned int err;
-
-       err = -ENOENT;
-
-       /* Lookup the dentry name at the base of our mount point */
-       dentry = d_lookup(nd->path.dentry, &nd->last);
-       if (!dentry)
-               goto out;
-
-       dput(nd->path.dentry);
-       nd->path.dentry = dentry;
+       return path->mnt->mnt_sb->s_dev == *(dev_t *)p;
+}
 
-       /* And follow the mount stack looking for our autofs mount */
-       while (follow_down(&nd->path.mnt, &nd->path.dentry)) {
-               ino = autofs4_dentry_ino(nd->path.dentry);
-               if (ino && ino->sbi->type & type) {
-                       err = 0;
-                       break;
-               }
-       }
-out:
-       return err;
+static int test_by_type(struct path *path, void *p)
+{
+       struct autofs_info *ino = autofs4_dentry_ino(path->dentry);
+       return ino && ino->sbi->type & *(unsigned *)p;
 }
 
 static void autofs_dev_ioctl_fd_install(unsigned int fd, struct file *file)
@@ -283,31 +248,25 @@ static void autofs_dev_ioctl_fd_install(unsigned int fd, struct file *file)
  * Open a file descriptor on the autofs mount point corresponding
  * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
  */
-static int autofs_dev_ioctl_open_mountpoint(const char *path, dev_t devid)
+static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
 {
-       struct file *filp;
-       struct nameidata nd;
        int err, fd;
 
        fd = get_unused_fd();
        if (likely(fd >= 0)) {
-               /* Get nameidata of the parent directory */
-               err = path_lookup(path, LOOKUP_PARENT, &nd);
+               struct file *filp;
+               struct path path;
+
+               err = find_autofs_mount(name, &path, test_by_dev, &devid);
                if (err)
                        goto out;
 
                /*
-                * Search down, within the parent, looking for an
-                * autofs super block that has the device number
+                * Find autofs super block that has the device number
                 * corresponding to the autofs fs we want to open.
                 */
-               err = autofs_dev_ioctl_find_super(&nd, devid);
-               if (err) {
-                       path_put(&nd.path);
-                       goto out;
-               }
 
-               filp = dentry_open(nd.path.dentry, nd.path.mnt, O_RDONLY,
+               filp = dentry_open(path.dentry, path.mnt, O_RDONLY,
                                   current_cred());
                if (IS_ERR(filp)) {
                        err = PTR_ERR(filp);
@@ -340,7 +299,7 @@ static int autofs_dev_ioctl_openmount(struct file *fp,
        param->ioctlfd = -1;
 
        path = param->path;
-       devid = param->openmount.devid;
+       devid = new_decode_dev(param->openmount.devid);
 
        err = 0;
        fd = autofs_dev_ioctl_open_mountpoint(path, devid);
@@ -475,8 +434,7 @@ static int autofs_dev_ioctl_requester(struct file *fp,
                                      struct autofs_dev_ioctl *param)
 {
        struct autofs_info *ino;
-       struct nameidata nd;
-       const char *path;
+       struct path path;
        dev_t devid;
        int err = -ENOENT;
 
@@ -485,32 +443,24 @@ static int autofs_dev_ioctl_requester(struct file *fp,
                goto out;
        }
 
-       path = param->path;
-       devid = new_encode_dev(sbi->sb->s_dev);
+       devid = sbi->sb->s_dev;
 
        param->requester.uid = param->requester.gid = -1;
 
-       /* Get nameidata of the parent directory */
-       err = path_lookup(path, LOOKUP_PARENT, &nd);
+       err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
        if (err)
                goto out;
 
-       err = autofs_dev_ioctl_find_super(&nd, devid);
-       if (err)
-               goto out_release;
-
-       ino = autofs4_dentry_ino(nd.path.dentry);
+       ino = autofs4_dentry_ino(path.dentry);
        if (ino) {
                err = 0;
-               autofs4_expire_wait(nd.path.dentry);
+               autofs4_expire_wait(path.dentry);
                spin_lock(&sbi->fs_lock);
                param->requester.uid = ino->uid;
                param->requester.gid = ino->gid;
                spin_unlock(&sbi->fs_lock);
        }
-
-out_release:
-       path_put(&nd.path);
+       path_put(&path);
 out:
        return err;
 }
@@ -569,8 +519,8 @@ static int autofs_dev_ioctl_ismountpoint(struct file *fp,
                                         struct autofs_sb_info *sbi,
                                         struct autofs_dev_ioctl *param)
 {
-       struct nameidata nd;
-       const char *path;
+       struct path path;
+       const char *name;
        unsigned int type;
        unsigned int devid, magic;
        int err = -ENOENT;
@@ -580,71 +530,46 @@ static int autofs_dev_ioctl_ismountpoint(struct file *fp,
                goto out;
        }
 
-       path = param->path;
+       name = param->path;
        type = param->ismountpoint.in.type;
 
        param->ismountpoint.out.devid = devid = 0;
        param->ismountpoint.out.magic = magic = 0;
 
        if (!fp || param->ioctlfd == -1) {
-               if (autofs_type_any(type)) {
-                       struct super_block *sb;
-
-                       err = path_lookup(path, LOOKUP_FOLLOW, &nd);
-                       if (err)
-                               goto out;
-
-                       sb = nd.path.dentry->d_sb;
-                       devid = new_encode_dev(sb->s_dev);
-               } else {
-                       struct autofs_info *ino;
-
-                       err = path_lookup(path, LOOKUP_PARENT, &nd);
-                       if (err)
-                               goto out;
-
-                       err = autofs_dev_ioctl_find_sbi_type(&nd, type);
-                       if (err)
-                               goto out_release;
-
-                       ino = autofs4_dentry_ino(nd.path.dentry);
-                       devid = autofs4_get_dev(ino->sbi);
-               }
-
+               if (autofs_type_any(type))
+                       err = kern_path(name, LOOKUP_FOLLOW, &path);
+               else
+                       err = find_autofs_mount(name, &path, test_by_type, &type);
+               if (err)
+                       goto out;
+               devid = new_encode_dev(path.mnt->mnt_sb->s_dev);
                err = 0;
-               if (nd.path.dentry->d_inode &&
-                   nd.path.mnt->mnt_root == nd.path.dentry) {
+               if (path.dentry->d_inode &&
+                   path.mnt->mnt_root == path.dentry) {
                        err = 1;
-                       magic = nd.path.dentry->d_inode->i_sb->s_magic;
+                       magic = path.dentry->d_inode->i_sb->s_magic;
                }
        } else {
-               dev_t dev = autofs4_get_dev(sbi);
+               dev_t dev = sbi->sb->s_dev;
 
-               err = path_lookup(path, LOOKUP_PARENT, &nd);
+               err = find_autofs_mount(name, &path, test_by_dev, &dev);
                if (err)
                        goto out;
 
-               err = autofs_dev_ioctl_find_super(&nd, dev);
-               if (err)
-                       goto out_release;
-
-               devid = dev;
+               devid = new_encode_dev(dev);
 
-               err = have_submounts(nd.path.dentry);
+               err = have_submounts(path.dentry);
 
-               if (nd.path.mnt->mnt_mountpoint != nd.path.mnt->mnt_root) {
-                       if (follow_down(&nd.path.mnt, &nd.path.dentry)) {
-                               struct inode *inode = nd.path.dentry->d_inode;
-                               magic = inode->i_sb->s_magic;
-                       }
+               if (path.mnt->mnt_mountpoint != path.mnt->mnt_root) {
+                       if (follow_down(&path.mnt, &path.dentry))
+                               magic = path.mnt->mnt_sb->s_magic;
                }
        }
 
        param->ismountpoint.out.devid = devid;
        param->ismountpoint.out.magic = magic;
-
-out_release:
-       path_put(&nd.path);
+       path_put(&path);
 out:
        return err;
 }