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[PATCH] r/o bind mounts: make access() use new r/o helper

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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 <viro@ZenIV.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Dave Hansen 2008-02-15 14:37:55 -08:00 committed by Al Viro
parent 9ac9b8474c
commit 2f676cbc0d
1 changed files with 11 additions and 2 deletions
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13
fs/open.c
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@ -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: