From: Andrew Morton <akpm@linux-foundation.org>
To: Djalal Harouni <tixxdz@opendz.org>
Cc: Hugh Dickins <hughd@google.com>,
Minchan Kim <minchan.kim@gmail.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Wu Fengguang <fengguang.wu@intel.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Al Viro <viro@zeniv.linux.org.uk>,
"J. Bruce Fields" <bfields@fieldses.org>,
Neil Brown <neilb@suse.de>,
Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Subject: Re: [PATCH] mm: add missing mutex lock arround notify_change
Date: Fri, 16 Dec 2011 12:55:56 -0800 [thread overview]
Message-ID: <20111216125556.db2bf308.akpm@linux-foundation.org> (raw)
In-Reply-To: <20111216112534.GA13147@dztty>
On Fri, 16 Dec 2011 12:25:34 +0100
Djalal Harouni <tixxdz@opendz.org> wrote:
>
> Calls to notify_change() must hold i_mutex.
>
It seems that this is true. It's tersely documented in
Documentation/filesystems/porting. It should be mentioned in the
non-existent notify_change() kerneldoc.
<does a quick audit>
fs/hpfs/namei.c and fs/nfsd/vfs.c:nfsd_setattr() aren't obviosuly
holding that lock when calling notify_change(). Everything else under
fs/ looks OK.
I'll add the below to my tree and shall slip it into linux-next, but not
mainline:
--- a/fs/attr.c~a
+++ a/fs/attr.c
@@ -171,6 +171,8 @@ int notify_change(struct dentry * dentry
struct timespec now;
unsigned int ia_valid = attr->ia_valid;
+ WARN_ON_ONCE(!mutex_is_locked(&inode->i_mutex));
+
if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) {
if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
return -EPERM;
@@ -245,5 +247,4 @@ int notify_change(struct dentry * dentry
return error;
}
-
EXPORT_SYMBOL(notify_change);
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -1994,10 +1994,16 @@ EXPORT_SYMBOL(should_remove_suid);
>
> static int __remove_suid(struct dentry *dentry, int kill)
> {
> + int ret;
> struct iattr newattrs;
>
> newattrs.ia_valid = ATTR_FORCE | kill;
> - return notify_change(dentry, &newattrs);
> +
> + mutex_lock(&dentry->d_inode->i_mutex);
> + ret = notify_change(dentry, &newattrs);
> + mutex_unlock(&dentry->d_inode->i_mutex);
> +
> + return ret;
> }
>
> int file_remove_suid(struct file *file)
Looks good to me.
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next prev parent reply other threads:[~2011-12-16 20:55 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-16 11:25 [PATCH] mm: add missing mutex lock arround notify_change Djalal Harouni
2011-12-16 20:55 ` Andrew Morton [this message]
2011-12-16 21:54 ` Djalal Harouni
2011-12-17 21:41 ` Al Viro
2011-12-17 22:10 ` Al Viro
2011-12-20 22:09 ` Ted Ts'o
2011-12-20 22:45 ` Ted Ts'o
2011-12-19 1:43 ` Dave Chinner
2011-12-19 2:03 ` Al Viro
2011-12-19 2:06 ` Al Viro
2011-12-19 5:07 ` Dave Chinner
2011-12-19 4:22 ` Dave Chinner
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