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Commit a7472bab authored by Al Viro's avatar Al Viro
Browse files

make nameidata_dentry_drop_rcu_maybe() always leave RCU mode 



Now we have do_follow_link() guaranteed to leave without dangling RCU
and the next step will get LOOKUP_RCU logics completely out of
link_path_walk().

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent ef7562d5

fs/namei.c

+11 −5
Original line number Diff line number Diff line
@@ -498,8 +498,15 @@ static int nameidata_dentry_drop_rcu(struct nameidata *nd, struct dentry *dentry 
/* Try to drop out of rcu-walk mode if we were in it, otherwise do nothing.  */

static inline int nameidata_dentry_drop_rcu_maybe(struct nameidata *nd, struct dentry *dentry)

{

	if (nd->flags & LOOKUP_RCU)

		return nameidata_dentry_drop_rcu(nd, dentry);

	if (nd->flags & LOOKUP_RCU) {

		if (unlikely(nameidata_dentry_drop_rcu(nd, dentry))) {

			nd->flags &= ~LOOKUP_RCU;

			nd->root.mnt = NULL;

			rcu_read_unlock();

			br_read_unlock(vfsmount_lock);

			return -ECHILD;

		}

	}

	return 0;

}
@@ -1424,7 +1431,7 @@ static int link_path_walk(const char *name, struct nameidata *nd) 
		if (inode && inode->i_op->follow_link) {

			err = do_follow_link(inode, &next, nd);

			if (err)

				goto return_err;

				return err;

			nd->inode = nd->path.dentry->d_inode;

		} else {

			path_to_nameidata(&next, nd);
@@ -1455,7 +1462,7 @@ static int link_path_walk(const char *name, struct nameidata *nd) 
		    (lookup_flags & LOOKUP_FOLLOW)) {

			err = do_follow_link(inode, &next, nd);

			if (err)

				goto return_err;

				return err;

			nd->inode = nd->path.dentry->d_inode;

		} else {

			path_to_nameidata(&next, nd);
@@ -1477,7 +1484,6 @@ static int link_path_walk(const char *name, struct nameidata *nd) 
	}

	if (!(nd->flags & LOOKUP_RCU))

		path_put(&nd->path);

return_err:

	if (nd->flags & LOOKUP_RCU) {

		nd->flags &= ~LOOKUP_RCU;

		nd->root.mnt = NULL;