[PATCH] autofs4: add v5 follow_link mount trigger method

This patch adds a follow_link inode method for the root of an autofs direct
mount trigger.  It also adds the corresponding mount options and updates the
show_mount method.

Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Al Viro <viro@ftp.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 52 insertions, 12 deletions

diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c
index 26eb1f024866..3f0048582248 100644
--- a/fs/autofs4/root.c
+++ b/fs/autofs4/root.c
@@ -4,7 +4,7 @@
  *
  *  Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
  *  Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org>
- *  Copyright 2001-2003 Ian Kent <raven@themaw.net>
+ *  Copyright 2001-2006 Ian Kent <raven@themaw.net>
  *
  * This file is part of the Linux kernel and is made available under
  * the terms of the GNU General Public License, version 2, or at your
@@ -30,6 +30,7 @@ static int autofs4_dir_close(struct inode *inode, struct file *file);
 static int autofs4_dir_readdir(struct file * filp, void * dirent, filldir_t filldir);
 static int autofs4_root_readdir(struct file * filp, void * dirent, filldir_t filldir);
 static struct dentry *autofs4_lookup(struct inode *,struct dentry *, struct nameidata *);
+static void *autofs4_follow_link(struct dentry *, struct nameidata *);
 
 struct file_operations autofs4_root_operations = {
         .open           = dcache_dir_open,
@@ -46,7 +47,7 @@ struct file_operations autofs4_dir_operations = {
         .readdir        = autofs4_dir_readdir,
 };
 
-struct inode_operations autofs4_root_inode_operations = {
+struct inode_operations autofs4_indirect_root_inode_operations = {
         .lookup         = autofs4_lookup,
         .unlink         = autofs4_dir_unlink,
         .symlink        = autofs4_dir_symlink,
@@ -54,6 +55,11 @@ struct inode_operations autofs4_root_inode_operations = {
         .rmdir          = autofs4_dir_rmdir,
 };
 
+struct inode_operations autofs4_direct_root_inode_operations = {
+        .lookup         = autofs4_lookup,
+        .follow_link    = autofs4_follow_link,
+};
+
 struct inode_operations autofs4_dir_inode_operations = {
         .lookup         = autofs4_lookup,
         .unlink         = autofs4_dir_unlink,
@@ -252,7 +258,7 @@ static int try_to_fill_dentry(struct dentry *dentry, int flags)
                  */
                 status = d_invalidate(dentry);
                 if (status != -EBUSY)
-                        return 0;
+                        return -ENOENT;
         }
 
         DPRINTK("dentry=%p %.*s ino=%p",
@@ -271,17 +277,17 @@ static int try_to_fill_dentry(struct dentry *dentry, int flags)
                 DPRINTK("mount done status=%d", status);
 
                 if (status && dentry->d_inode)
-                        return 0; /* Try to get the kernel to invalidate this dentry */
+                        return status; /* Try to get the kernel to invalidate this dentry */
 
                 /* Turn this into a real negative dentry? */
                 if (status == -ENOENT) {
                         spin_lock(&dentry->d_lock);
                         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
                         spin_unlock(&dentry->d_lock);
-                        return 0;
+                        return status;
                 } else if (status) {
                         /* Return a negative dentry, but leave it "pending" */
-                        return 0;
+                        return status;
                 }
         /* Trigger mount for path component or follow link */
         } else if (flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY) ||
@@ -300,7 +306,7 @@ static int try_to_fill_dentry(struct dentry *dentry, int flags)
                         spin_lock(&dentry->d_lock);
                         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
                         spin_unlock(&dentry->d_lock);
-                        return 0;
+                        return status;
                 }
         }
 
@@ -311,7 +317,41 @@ static int try_to_fill_dentry(struct dentry *dentry, int flags)
         spin_lock(&dentry->d_lock);
         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
         spin_unlock(&dentry->d_lock);
-        return 1;
+        return status;
+}
+
+/* For autofs direct mounts the follow link triggers the mount */
+static void *autofs4_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+        struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
+        int oz_mode = autofs4_oz_mode(sbi);
+        unsigned int lookup_type;
+        int status;
+
+        DPRINTK("dentry=%p %.*s oz_mode=%d nd->flags=%d",
+                dentry, dentry->d_name.len, dentry->d_name.name, oz_mode,
+                nd->flags);
+
+        /* If it's our master or we shouldn't trigger a mount we're done */
+        lookup_type = nd->flags & (LOOKUP_CONTINUE | LOOKUP_DIRECTORY);
+        if (oz_mode || !lookup_type)
+                goto done;
+
+        status = try_to_fill_dentry(dentry, 0);
+        if (status)
+                goto out_error;
+
+        if (!autofs4_follow_mount(&nd->mnt, &nd->dentry)) {
+                status = -ENOENT;
+                goto out_error;
+        }
+
+done:
+        return NULL;
+
+out_error:
+        path_release(nd);
+        return ERR_PTR(status);
 }
 
 /*
@@ -326,13 +366,13 @@ static int autofs4_revalidate(struct dentry *dentry, struct nameidata *nd)
         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
         int oz_mode = autofs4_oz_mode(sbi);
         int flags = nd ? nd->flags : 0;
-        int status = 1;
+        int status = 0;
 
         /* Pending dentry */
         if (autofs4_ispending(dentry)) {
                 if (!oz_mode)
                         status = try_to_fill_dentry(dentry, flags);
-                return status;
+                return !status;
         }
 
         /* Negative dentry.. invalidate if "old" */
@@ -349,14 +389,14 @@ static int autofs4_revalidate(struct dentry *dentry, struct nameidata *nd)
                 spin_unlock(&dcache_lock);
                 if (!oz_mode)
                         status = try_to_fill_dentry(dentry, flags);
-                return status;
+                return !status;
         }
         spin_unlock(&dcache_lock);
 
         return 1;
 }
 
-static void autofs4_dentry_release(struct dentry *de)
+void autofs4_dentry_release(struct dentry *de)
 {
         struct autofs_info *inf;