[PATCH] replace hack with dget/mntget usage in fs/dcookies.c

[PATCH] replace hack with dget/mntget usage in fs/dcookies.c

[Kirill Korotaev]

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This patch replaces manual incrementing of refcounters on dentry/mnt in 
fs/dcookie.c with calls to dget()/mntget().
Noticed this when tried to change logic in dget() and it began to oops.

Signed-Off-By: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Signed-Off-By: Pavel Emelianov <xemul@sw.ru>
Signed-Off-By: Kirill Korotaev <dev@sw.ru>

Kirill

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--- linux-2.6.8.1-t032/fs/dcookies.c.dget	2004-08-14 14:54:46.000000000 +0400
+++ linux-2.6.8.1-t032/fs/dcookies.c	2005-08-23 14:09:00.000000000 +0400
@@ -93,12 +93,10 @@ static struct dcookie_struct * alloc_dco
 	if (!dcs)
 		return NULL;
 
-	atomic_inc(&dentry->d_count);
-	atomic_inc(&vfsmnt->mnt_count);
 	dentry->d_cookie = dcs;
 
-	dcs->dentry = dentry;
-	dcs->vfsmnt = vfsmnt;
+	dcs->dentry = dget(dentry);
+	dcs->vfsmnt = mntget(vfsmnt);
 	hash_dcookie(dcs);
 
 	return dcs;

Re: [PATCH] replace hack with dget/mntget usage in fs/dcookies.c

[Andrew Morton]

Kirill Korotaev <dev@sw.ru> wrote:
>
> This patch replaces manual incrementing of refcounters on dentry/mnt in 
>  fs/dcookie.c with calls to dget()/mntget().
>
> ...
>
>  --- linux-2.6.8.1-t032/fs/dcookies.c.dget	2004-08-14 14:54:46.000000000 +0400
>  +++ linux-2.6.8.1-t032/fs/dcookies.c	2005-08-23 14:09:00.000000000 +0400

Whoa.  Medieval kernel.

>  @@ -93,12 +93,10 @@ static struct dcookie_struct * alloc_dco
>   	if (!dcs)
>   		return NULL;
>   
>  -	atomic_inc(&dentry->d_count);
>  -	atomic_inc(&vfsmnt->mnt_count);
>   	dentry->d_cookie = dcs;
>   
>  -	dcs->dentry = dentry;
>  -	dcs->vfsmnt = vfsmnt;
>  +	dcs->dentry = dget(dentry);
>  +	dcs->vfsmnt = mntget(vfsmnt);
>   	hash_dcookie(dcs);
>   
>   	return dcs;

That's already there.