Re: [PATCH 2/2] AUTOFS: Make sure all dentries refs are releasedbefore calling kill_anon_super()

From: Ian Kent
Date: Fri Jul 07 2006 - 04:25:07 EST



Thanks for you patience.
Carried out a number of basic autofs tests without problem.

So in so far as autofs4 is concerned:

On Fri, 2006-06-30 at 13:33 +0100, David Howells wrote:
> From: David Howells <dhowells@xxxxxxxxxx>
>
> Make sure all dentries refs are released before calling kill_anon_super() so
> that the assumption that generic_shutdown_super() can completely destroy the
> dentry tree for there will be no external references holds true.
>
> What was being done in the put_super() superblock op, is now done in the
> kill_sb() filesystem op instead, prior to calling kill_anon_super().
>
> This makes the struct autofs_sb_info::root member variable redundant (since
> sb->s_root is still available), and so that is removed. The calls to
> shrink_dcache_sb() are also removed since they're also redundant as
> shrink_dcache_for_umount() will now be called after the cleanup routine.
>
> Signed-Off-By: David Howells <dhowells@xxxxxxxxxx>
Acked-by: Ian Kent <raven@xxxxxxxxxx>

> ---
>
> fs/autofs4/autofs_i.h | 3 +--
> fs/autofs4/init.c | 2 +-
> fs/autofs4/inode.c | 22 ++++------------------
> fs/autofs4/waitq.c | 1 -
> 4 files changed, 6 insertions(+), 22 deletions(-)
>
> diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h
> index d6603d0..47e38f3 100644
> --- a/fs/autofs4/autofs_i.h
> +++ b/fs/autofs4/autofs_i.h
> @@ -96,7 +96,6 @@ #define AUTOFS_TYPE_OFFSET 0x0004
>
> struct autofs_sb_info {
> u32 magic;
> - struct dentry *root;
> int pipefd;
> struct file *pipe;
> pid_t oz_pgrp;
> @@ -231,4 +230,4 @@ out:
> }
>
> void autofs4_dentry_release(struct dentry *);
> -
> +extern void autofs4_kill_sb(struct super_block *);
> diff --git a/fs/autofs4/init.c b/fs/autofs4/init.c
> index 5d91933..723a1c5 100644
> --- a/fs/autofs4/init.c
> +++ b/fs/autofs4/init.c
> @@ -24,7 +24,7 @@ static struct file_system_type autofs_fs
> .owner = THIS_MODULE,
> .name = "autofs",
> .get_sb = autofs_get_sb,
> - .kill_sb = kill_anon_super,
> + .kill_sb = autofs4_kill_sb,
> };
>
> static int __init init_autofs4_fs(void)
> diff --git a/fs/autofs4/inode.c b/fs/autofs4/inode.c
> index fde78b1..1bf68c5 100644
> --- a/fs/autofs4/inode.c
> +++ b/fs/autofs4/inode.c
> @@ -95,7 +95,7 @@ void autofs4_free_ino(struct autofs_info
> */
> static void autofs4_force_release(struct autofs_sb_info *sbi)
> {
> - struct dentry *this_parent = sbi->root;
> + struct dentry *this_parent = sbi->sb->s_root;
> struct list_head *next;
>
> spin_lock(&dcache_lock);
> @@ -126,7 +126,7 @@ resume:
> spin_lock(&dcache_lock);
> }
>
> - if (this_parent != sbi->root) {
> + if (this_parent != sbi->sb->s_root) {
> struct dentry *dentry = this_parent;
>
> next = this_parent->d_u.d_child.next;
> @@ -139,15 +139,9 @@ resume:
> goto resume;
> }
> spin_unlock(&dcache_lock);
> -
> - dput(sbi->root);
> - sbi->root = NULL;
> - shrink_dcache_sb(sbi->sb);
> -
> - return;
> }
>
> -static void autofs4_put_super(struct super_block *sb)
> +void autofs4_kill_sb(struct super_block *sb)
> {
> struct autofs_sb_info *sbi = autofs4_sbi(sb);
>
> @@ -162,6 +156,7 @@ static void autofs4_put_super(struct sup
> kfree(sbi);
>
> DPRINTK("shutting down");
> + kill_anon_super(sb);
> }
>
> static int autofs4_show_options(struct seq_file *m, struct vfsmount *mnt)
> @@ -188,7 +183,6 @@ static int autofs4_show_options(struct s
> }
>
> static struct super_operations autofs4_sops = {
> - .put_super = autofs4_put_super,
> .statfs = simple_statfs,
> .show_options = autofs4_show_options,
> };
> @@ -314,7 +308,6 @@ int autofs4_fill_super(struct super_bloc
>
> s->s_fs_info = sbi;
> sbi->magic = AUTOFS_SBI_MAGIC;
> - sbi->root = NULL;
> sbi->pipefd = -1;
> sbi->catatonic = 0;
> sbi->exp_timeout = 0;
> @@ -396,13 +389,6 @@ int autofs4_fill_super(struct super_bloc
> sbi->pipefd = pipefd;
>
> /*
> - * Take a reference to the root dentry so we get a chance to
> - * clean up the dentry tree on umount.
> - * See autofs4_force_release.
> - */
> - sbi->root = dget(root);
> -
> - /*
> * Success! Install the root dentry now to indicate completion.
> */
> s->s_root = root;
> diff --git a/fs/autofs4/waitq.c b/fs/autofs4/waitq.c
> index ce103e7..c0a6c8d 100644
> --- a/fs/autofs4/waitq.c
> +++ b/fs/autofs4/waitq.c
> @@ -45,7 +45,6 @@ void autofs4_catatonic_mode(struct autof
> fput(sbi->pipe); /* Close the pipe */
> sbi->pipe = NULL;
> }
> - shrink_dcache_sb(sbi->sb);
> }
>
> static int autofs4_write(struct file *file, const void *addr, int bytes)
-
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