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Subject[RFC:PATCH 2/4] 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.

--- linux-2.6.16-rc2-mm1/fs/autofs4/inode.c.v5-follow_link 2006-02-12 20:38:17.000000000 +0800
+++ linux-2.6.16-rc2-mm1/fs/autofs4/inode.c 2006-02-12 20:43:45.000000000 +0800
@@ -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 s
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_s
.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,
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_mkroo
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_bloc
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_bloc
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:
--- linux-2.6.16-rc2-mm1/fs/autofs4/root.c.v5-follow_link 2006-02-12 20:38:17.000000000 +0800
+++ linux-2.6.16-rc2-mm1/fs/autofs4/root.c 2006-02-12 20:53:39.000000000 +0800
@@ -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 inod
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 *);

const struct file_operations autofs4_root_operations = {
.open = dcache_dir_open,
@@ -46,7 +47,7 @@ const struct file_operations autofs4_dir
.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_ino
.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 den
*/
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 den
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 den
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 den
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 den
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 den
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;

--- linux-2.6.16-rc2-mm1/fs/autofs4/autofs_i.h.v5-follow_link 2006-02-12 20:38:17.000000000 +0800
+++ linux-2.6.16-rc2-mm1/fs/autofs4/autofs_i.h 2006-02-12 20:43:45.000000000 +0800
@@ -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;
@@ -161,7 +167,8 @@ int autofs4_expire_multi(struct super_bl

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 const struct file_operations autofs4_dir_operations;
extern const struct file_operations autofs4_root_operations;

-
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