[PATCH] r/o bind mounts: make access() use new r/o helper (2f676cbc) · Commits · 戴 / test

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>

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:

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