From: Dave Hansen Date: Fri, 15 Feb 2008 22:37:55 +0000 (-0800) Subject: [PATCH] r/o bind mounts: make access() use new r/o helper X-Git-Tag: v2.6.26-rc1~1134^2~5 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=2f676cbc0d60ae806216c7a61c6971bd72dedde8;p=linux-2.6-omap-h63xx.git [PATCH] r/o bind mounts: make access() use new r/o helper It is OK to let access() go without using a mnt_want/drop_write() pair because it doesn't actually do writes to the filesystem, and it is inherently racy anyway. This is a rare case when it is OK to use __mnt_is_readonly() directly. Acked-by: Al Viro Signed-off-by: Christoph Hellwig Signed-off-by: Dave Hansen Signed-off-by: Andrew Morton Signed-off-by: Al Viro --- diff --git a/fs/open.c b/fs/open.c index 4d690e33446..e58382d57e7 100644 --- a/fs/open.c +++ b/fs/open.c @@ -459,8 +459,17 @@ asmlinkage long sys_faccessat(int dfd, const char __user *filename, int mode) if(res || !(mode & S_IWOTH) || special_file(nd.path.dentry->d_inode->i_mode)) goto out_path_release; - - if(IS_RDONLY(nd.path.dentry->d_inode)) + /* + * This is a rare case where using __mnt_is_readonly() + * is OK without a mnt_want/drop_write() pair. Since + * no actual write to the fs is performed here, we do + * not need to telegraph to that to anyone. + * + * By doing this, we accept that this access is + * inherently racy and know that the fs may change + * state before we even see this result. + */ + if (__mnt_is_readonly(nd.path.mnt)) res = -EROFS; out_path_release: