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Commit fac7d191 authored by Al Viro's avatar Al Viro
Browse files

fix EOPENSTALE bug in do_last() 



EOPENSTALE occuring at the last component of a trailing symlink ends up
with do_last() retrying its lookup.  After the symlink body has been
discarded.  The thing is, all this retry_lookup logics in there is not
needed at all - the upper layers will do the right thing if we simply
return that -EOPENSTALE as we would with any other error.  Trying to
microoptimize in do_last() is a lot of headache for no good reason.

Cc: stable@vger.kernel.org # v4.2+
Tested-by: default avatarOleg Drokin <green@linuxhacker.ru>
Reviewed-and-Tested-by: default avatarJeff Layton <jlayton@poochiereds.net>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 1a695a90

fs/namei.c

+4 −39
Original line number Diff line number Diff line
@@ -3166,9 +3166,7 @@ static int do_last(struct nameidata *nd, 
	int acc_mode = op->acc_mode;

	unsigned seq;

	struct inode *inode;

	struct path save_parent = { .dentry = NULL, .mnt = NULL };

	struct path path;

	bool retried = false;

	int error;



	nd->flags &= ~LOOKUP_PARENT;
@@ -3211,7 +3209,6 @@ static int do_last(struct nameidata *nd, 
			return -EISDIR;

	}



retry_lookup:

	if (open_flag & (O_CREAT | O_TRUNC | O_WRONLY | O_RDWR)) {

		error = mnt_want_write(nd->path.mnt);

		if (!error)
@@ -3292,23 +3289,14 @@ static int do_last(struct nameidata *nd, 
	if (unlikely(error))

		return error;



	if ((nd->flags & LOOKUP_RCU) || nd->path.mnt != path.mnt) {

	path_to_nameidata(&path, nd);

	} else {

		save_parent.dentry = nd->path.dentry;

		save_parent.mnt = mntget(path.mnt);

		nd->path.dentry = path.dentry;



	}

	nd->inode = inode;

	nd->seq = seq;

	/* Why this, you ask?  _Now_ we might have grown LOOKUP_JUMPED... */

finish_open:

	error = complete_walk(nd);

	if (error) {

		path_put(&save_parent);

	if (error)

		return error;

	}

	audit_inode(nd->name, nd->path.dentry, 0);

	error = -EISDIR;

	if ((open_flag & O_CREAT) && d_is_dir(nd->path.dentry))
@@ -3331,13 +3319,9 @@ static int do_last(struct nameidata *nd, 
		goto out;

	BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */

	error = vfs_open(&nd->path, file, current_cred());

	if (!error) {

		*opened |= FILE_OPENED;

	} else {

		if (error == -EOPENSTALE)

			goto stale_open;

	if (error)

		goto out;

	}

	*opened |= FILE_OPENED;

opened:

	error = open_check_o_direct(file);

	if (!error)
@@ -3353,26 +3337,7 @@ static int do_last(struct nameidata *nd, 
	}

	if (got_write)

		mnt_drop_write(nd->path.mnt);

	path_put(&save_parent);

	return error;



stale_open:

	/* If no saved parent or already retried then can't retry */

	if (!save_parent.dentry || retried)

		goto out;



	BUG_ON(save_parent.dentry != dir);

	path_put(&nd->path);

	nd->path = save_parent;

	nd->inode = dir->d_inode;

	save_parent.mnt = NULL;

	save_parent.dentry = NULL;

	if (got_write) {

		mnt_drop_write(nd->path.mnt);

		got_write = false;

	}

	retried = true;

	goto retry_lookup;

}



static int do_tmpfile(struct nameidata *nd, unsigned flags,