CIFS: Use d_automount() rather than abusing follow_link()

Make CIFS use the new d_automount() dentry operation rather than abusing
follow_link() on directories.

[NOTE: THIS IS UNTESTED!]

Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Steve French <sfrench@samba.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/cifs/cifs_dfs_ref.c b/fs/cifs/cifs_dfs_ref.c
index 83479cf..0fc1638 100644 (file)
--- a/fs/cifs/cifs_dfs_ref.c
+++ b/fs/cifs/cifs_dfs_ref.c
@@ -255,32 +255,6 @@ static struct vfsmount *cifs_dfs_do_refmount(struct cifs_sb_info *cifs_sb,
 
 }
 
-static int add_mount_helper(struct vfsmount *newmnt, struct nameidata *nd,
-                               struct list_head *mntlist)
-{
-       /* stolen from afs code */
-       int err;
-
-       mntget(newmnt);
-       err = do_add_mount(newmnt, &nd->path, nd->path.mnt->mnt_flags | MNT_SHRINKABLE, mntlist);
-       switch (err) {
-       case 0:
-               path_put(&nd->path);
-               nd->path.mnt = newmnt;
-               nd->path.dentry = dget(newmnt->mnt_root);
-               schedule_delayed_work(&cifs_dfs_automount_task,
-                                     cifs_dfs_mountpoint_expiry_timeout);
-               break;
-       case -EBUSY:
-               /* someone else made a mount here whilst we were busy */
-               err = follow_down(&nd->path, false);
-       default:
-               mntput(newmnt);
-               break;
-       }
-       return err;
-}
-
 static void dump_referral(const struct dfs_info3_param *ref)
 {
        cFYI(1, "DFS: ref path: %s", ref->path_name);
@@ -290,45 +264,43 @@ static void dump_referral(const struct dfs_info3_param *ref)
                                ref->path_consumed);
 }
 
-
-static void*
-cifs_dfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
+/*
+ * Create a vfsmount that we can automount
+ */
+static struct vfsmount *cifs_dfs_do_automount(struct dentry *mntpt)
 {
        struct dfs_info3_param *referrals = NULL;
        unsigned int num_referrals = 0;
        struct cifs_sb_info *cifs_sb;
        struct cifsSesInfo *ses;
-       char *full_path = NULL;
+       char *full_path;
        int xid, i;
-       int rc = 0;
-       struct vfsmount *mnt = ERR_PTR(-ENOENT);
+       int rc;
+       struct vfsmount *mnt;
        struct tcon_link *tlink;
 
        cFYI(1, "in %s", __func__);
-       BUG_ON(IS_ROOT(dentry));
+       BUG_ON(IS_ROOT(mntpt));
 
        xid = GetXid();
 
-       dput(nd->path.dentry);
-       nd->path.dentry = dget(dentry);
-
        /*
         * The MSDFS spec states that paths in DFS referral requests and
         * responses must be prefixed by a single '\' character instead of
         * the double backslashes usually used in the UNC. This function
         * gives us the latter, so we must adjust the result.
         */
-       full_path = build_path_from_dentry(dentry);
-       if (full_path == NULL) {
-               rc = -ENOMEM;
-               goto out_err;
-       }
+       mnt = ERR_PTR(-ENOMEM);
+       full_path = build_path_from_dentry(mntpt);
+       if (full_path == NULL)
+               goto free_xid;
 
-       cifs_sb = CIFS_SB(dentry->d_inode->i_sb);
+       cifs_sb = CIFS_SB(mntpt->d_inode->i_sb);
        tlink = cifs_sb_tlink(cifs_sb);
+       mnt = ERR_PTR(-EINVAL);
        if (IS_ERR(tlink)) {
-               rc = PTR_ERR(tlink);
-               goto out_err;
+               mnt = ERR_CAST(tlink);
+               goto free_full_path;
        }
        ses = tlink_tcon(tlink)->ses;
 
@@ -338,46 +310,77 @@ cifs_dfs_follow_mountpoint(struct dentry *dentry, struct nameidata *nd)
 
        cifs_put_tlink(tlink);
 
+       mnt = ERR_PTR(-ENOENT);
        for (i = 0; i < num_referrals; i++) {
                int len;
-               dump_referral(referrals+i);
+               dump_referral(referrals + i);
                /* connect to a node */
                len = strlen(referrals[i].node_name);
                if (len < 2) {
                        cERROR(1, "%s: Net Address path too short: %s",
                                        __func__, referrals[i].node_name);
-                       rc = -EINVAL;
-                       goto out_err;
+                       mnt = ERR_PTR(-EINVAL);
+                       break;
                }
                mnt = cifs_dfs_do_refmount(cifs_sb,
                                full_path, referrals + i);
                cFYI(1, "%s: cifs_dfs_do_refmount:%s , mnt:%p", __func__,
                                        referrals[i].node_name, mnt);
-
-               /* complete mount procedure if we accured submount */
                if (!IS_ERR(mnt))
-                       break;
+                       goto success;
        }
 
-       /* we need it cause for() above could exit without valid submount */
-       rc = PTR_ERR(mnt);
-       if (IS_ERR(mnt))
-               goto out_err;
-
-       rc = add_mount_helper(mnt, nd, &cifs_dfs_automount_list);
+       /* no valid submounts were found; return error from get_dfs_path() by
+        * preference */
+       if (rc != 0)
+               mnt = ERR_PTR(rc);
 
-out:
-       FreeXid(xid);
+success:
        free_dfs_info_array(referrals, num_referrals);
+free_full_path:
        kfree(full_path);
+free_xid:
+       FreeXid(xid);
        cFYI(1, "leaving %s" , __func__);
-       return ERR_PTR(rc);
-out_err:
-       path_put(&nd->path);
-       goto out;
+       return mnt;
+}
+
+/*
+ * Attempt to automount the referral
+ */
+struct vfsmount *cifs_dfs_d_automount(struct path *path)
+{
+       struct vfsmount *newmnt;
+       int err;
+
+       cFYI(1, "in %s", __func__);
+
+       newmnt = cifs_dfs_do_automount(path->dentry);
+       if (IS_ERR(newmnt)) {
+               cFYI(1, "leaving %s [automount failed]" , __func__);
+               return newmnt;
+       }
+
+       mntget(newmnt);
+       err = do_add_mount(newmnt, path, path->mnt->mnt_flags | MNT_SHRINKABLE,
+                          &cifs_dfs_automount_list);
+       switch (err) {
+       case 0:
+               schedule_delayed_work(&cifs_dfs_automount_task,
+                                     cifs_dfs_mountpoint_expiry_timeout);
+               cFYI(1, "leaving %s [ok]" , __func__);
+               return newmnt;
+       case -EBUSY:
+               /* someone else made a mount here whilst we were busy */
+               mntput(newmnt);
+               cFYI(1, "leaving %s [EBUSY]" , __func__);
+               return NULL;
+       default:
+               mntput(newmnt);
+               cFYI(1, "leaving %s [error %d]" , __func__, err);
+               return ERR_PTR(err);
+       }
 }
 
 const struct inode_operations cifs_dfs_referral_inode_operations = {
-       .follow_link = cifs_dfs_follow_mountpoint,
 };
-

diff --git a/fs/cifs/cifsfs.h b/fs/cifs/cifsfs.h
index 897b2b2..851030f 100644 (file)
--- a/fs/cifs/cifsfs.h
+++ b/fs/cifs/cifsfs.h
@@ -93,6 +93,12 @@ extern int cifs_readdir(struct file *file, void *direntry, filldir_t filldir);
 extern const struct dentry_operations cifs_dentry_ops;
 extern const struct dentry_operations cifs_ci_dentry_ops;
 
+#ifdef CONFIG_CIFS_DFS_UPCALL
+extern struct vfsmount *cifs_dfs_d_automount(struct path *path);
+#else
+#define cifs_dfs_d_automount NULL
+#endif
+
 /* Functions related to symlinks */
 extern void *cifs_follow_link(struct dentry *direntry, struct nameidata *nd);
 extern void cifs_put_link(struct dentry *direntry,

diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index 1e95dd6..dd5f229 100644 (file)
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -675,6 +675,7 @@ cifs_d_revalidate(struct dentry *direntry, struct nameidata *nd)
 
 const struct dentry_operations cifs_dentry_ops = {
        .d_revalidate = cifs_d_revalidate,
+       .d_automount = cifs_dfs_d_automount,
 /* d_delete:       cifs_d_delete,      */ /* not needed except for debugging */
 };
 
@@ -711,4 +712,5 @@ const struct dentry_operations cifs_ci_dentry_ops = {
        .d_revalidate = cifs_d_revalidate,
        .d_hash = cifs_ci_hash,
        .d_compare = cifs_ci_compare,
+       .d_automount = cifs_dfs_d_automount,
 };

diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c
index b06b606..6c9ee80 100644 (file)
--- a/fs/cifs/inode.c
+++ b/fs/cifs/inode.c
@@ -32,7 +32,7 @@
 #include "fscache.h"
 
 
-static void cifs_set_ops(struct inode *inode, const bool is_dfs_referral)
+static void cifs_set_ops(struct inode *inode)
 {
        struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 
@@ -60,7 +60,7 @@ static void cifs_set_ops(struct inode *inode, const bool is_dfs_referral)
                break;
        case S_IFDIR:
 #ifdef CONFIG_CIFS_DFS_UPCALL
-               if (is_dfs_referral) {
+               if (IS_AUTOMOUNT(inode)) {
                        inode->i_op = &cifs_dfs_referral_inode_operations;
                } else {
 #else /* NO DFS support, treat as a directory */
@@ -167,7 +167,9 @@ cifs_fattr_to_inode(struct inode *inode, struct cifs_fattr *fattr)
        }
        spin_unlock(&inode->i_lock);
 
-       cifs_set_ops(inode, fattr->cf_flags & CIFS_FATTR_DFS_REFERRAL);
+       if (fattr->cf_flags & CIFS_FATTR_DFS_REFERRAL)
+               inode->i_flags |= S_AUTOMOUNT;
+       cifs_set_ops(inode);
 }
 
 void