Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 2f676cbc authored by Dave Hansen's avatar Dave Hansen Committed by Al Viro
Browse files

[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: default avatarAl Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: default avatarChristoph Hellwig <hch@infradead.org>
Signed-off-by: default avatarDave Hansen <haveblue@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 9ac9b847

fs/open.c

+11 −2
Original line number Diff line number Diff line
@@ -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: