[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>

3 files changed, 103 insertions, 21 deletions

diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h
index bc1b0543d2b6..ed388a1d8fc4 100644
--- a/fs/autofs4/autofs_i.h
+++ b/fs/autofs4/autofs_i.h
@@ -3,6 +3,7 @@
  * linux/fs/autofs/autofs_i.h
  *
  *   Copyright 1997-1998 Transmeta Corporation - All Rights Reserved
+ *   Copyright 2005-2006 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
@@ -84,6 +85,10 @@ struct autofs_wait_queue {
 
 #define AUTOFS_SBI_MAGIC 0x6d4a556d
 
+#define AUTOFS_TYP_INDIRECT     0x0001
+#define AUTOFS_TYP_DIRECT       0x0002
+#define AUTOFS_TYP_OFFSET       0x0004
+
 struct autofs_sb_info {
         u32 magic;
         struct dentry *root;
@@ -96,6 +101,7 @@ struct autofs_sb_info {
         int min_proto;
         int max_proto;
         unsigned long exp_timeout;
+        unsigned int type;
         int reghost_enabled;
         int needs_reghost;
         struct super_block *sb;
@@ -162,6 +168,8 @@ int autofs4_expire_multi(struct super_block *, struct vfsmount *,
 extern struct inode_operations autofs4_symlink_inode_operations;
 extern struct inode_operations autofs4_dir_inode_operations;
 extern struct inode_operations autofs4_root_inode_operations;
+extern struct inode_operations autofs4_indirect_root_inode_operations;
+extern struct inode_operations autofs4_direct_root_inode_operations;
 extern struct file_operations autofs4_dir_operations;
 extern struct file_operations autofs4_root_operations;
 
diff --git a/fs/autofs4/inode.c b/fs/autofs4/inode.c
index d9a71dab40fc..3801bed94e45 100644
--- a/fs/autofs4/inode.c
+++ b/fs/autofs4/inode.c
@@ -3,6 +3,7 @@
  * linux/fs/autofs/inode.c
  *
  *  Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
+ *  Copyright 2005-2006 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
@@ -177,6 +178,13 @@ static int autofs4_show_options(struct seq_file *m, struct vfsmount *mnt)
         seq_printf(m, ",minproto=%d", sbi->min_proto);
         seq_printf(m, ",maxproto=%d", sbi->max_proto);
 
+        if (sbi->type & AUTOFS_TYP_OFFSET)
+                seq_printf(m, ",offset");
+        else if (sbi->type & AUTOFS_TYP_DIRECT)
+                seq_printf(m, ",direct");
+        else
+                seq_printf(m, ",indirect");
+
         return 0;
 }
 
@@ -186,7 +194,8 @@ static struct super_operations autofs4_sops = {
         .show_options   = autofs4_show_options,
 };
 
-enum {Opt_err, Opt_fd, Opt_uid, Opt_gid, Opt_pgrp, Opt_minproto, Opt_maxproto};
+enum {Opt_err, Opt_fd, Opt_uid, Opt_gid, Opt_pgrp, Opt_minproto, Opt_maxproto,
+        Opt_indirect, Opt_direct, Opt_offset};
 
 static match_table_t tokens = {
         {Opt_fd, "fd=%u"},
@@ -195,11 +204,15 @@ static match_table_t tokens = {
         {Opt_pgrp, "pgrp=%u"},
         {Opt_minproto, "minproto=%u"},
         {Opt_maxproto, "maxproto=%u"},
+        {Opt_indirect, "indirect"},
+        {Opt_direct, "direct"},
+        {Opt_offset, "offset"},
         {Opt_err, NULL}
 };
 
 static int parse_options(char *options, int *pipefd, uid_t *uid, gid_t *gid,
-                         pid_t *pgrp, int *minproto, int *maxproto)
+                         pid_t *pgrp, unsigned int *type,
+                         int *minproto, int *maxproto)
 {
         char *p;
         substring_t args[MAX_OPT_ARGS];
@@ -253,6 +266,15 @@ static int parse_options(char *options, int *pipefd, uid_t *uid, gid_t *gid,
                                 return 1;
                         *maxproto = option;
                         break;
+                case Opt_indirect:
+                        *type = AUTOFS_TYP_INDIRECT;
+                        break;
+                case Opt_direct:
+                        *type = AUTOFS_TYP_DIRECT;
+                        break;
+                case Opt_offset:
+                        *type = AUTOFS_TYP_DIRECT | AUTOFS_TYP_OFFSET;
+                        break;
                 default:
                         return 1;
                 }
@@ -271,6 +293,11 @@ static struct autofs_info *autofs4_mkroot(struct autofs_sb_info *sbi)
         return ino;
 }
 
+void autofs4_dentry_release(struct dentry *);
+static struct dentry_operations autofs4_sb_dentry_operations = {
+        .d_release      = autofs4_dentry_release,
+};
+
 int autofs4_fill_super(struct super_block *s, void *data, int silent)
 {
         struct inode * root_inode;
@@ -297,6 +324,7 @@ int autofs4_fill_super(struct super_block *s, void *data, int silent)
         sbi->sb = s;
         sbi->version = 0;
         sbi->sub_version = 0;
+        sbi->type = 0;
         sbi->min_proto = 0;
         sbi->max_proto = 0;
         mutex_init(&sbi->wq_mutex);
@@ -315,27 +343,31 @@ int autofs4_fill_super(struct super_block *s, void *data, int silent)
         if (!ino)
                 goto fail_free;
         root_inode = autofs4_get_inode(s, ino);
-        kfree(ino);
         if (!root_inode)
-                goto fail_free;
+                goto fail_ino;
 
-        root_inode->i_op = &autofs4_root_inode_operations;
-        root_inode->i_fop = &autofs4_root_operations;
         root = d_alloc_root(root_inode);
-        pipe = NULL;
-
         if (!root)
                 goto fail_iput;
+        pipe = NULL;
+
+        root->d_op = &autofs4_sb_dentry_operations;
+        root->d_fsdata = ino;
 
         /* Can this call block? */
         if (parse_options(data, &pipefd,
                           &root_inode->i_uid, &root_inode->i_gid,
-                          &sbi->oz_pgrp,
+                          &sbi->oz_pgrp, &sbi->type,
                           &sbi->min_proto, &sbi->max_proto)) {
                 printk("autofs: called with bogus options\n");
                 goto fail_dput;
         }
 
+        root_inode->i_fop = &autofs4_root_operations;
+        root_inode->i_op = sbi->type & AUTOFS_TYP_DIRECT ?
+                        &autofs4_direct_root_inode_operations :
+                        &autofs4_indirect_root_inode_operations;
+
         /* Couldn't this be tested earlier? */
         if (sbi->max_proto < AUTOFS_MIN_PROTO_VERSION ||
             sbi->min_proto > AUTOFS_MAX_PROTO_VERSION) {
@@ -391,6 +423,8 @@ fail_dput:
 fail_iput:
         printk("autofs: get root dentry failed\n");
         iput(root_inode);
+fail_ino:
+        kfree(ino);
 fail_free:
         kfree(sbi);
 fail_unlock:
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;