[RFC,v4,27/69] namei: invert the meaning of WALK_FOLLOW

Commit Message

Al Viro March 13, 2020, 11:53 p.m. UTC

From: Al Viro <[e-mail]>

old flags & WALK_FOLLOW <=> new !(flags & WALK_TRAILING)
That's what that flag had really been used for.

Signed-off-by: Al Viro <[e-mail]>
---
 fs/namei.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

Comments

Linus Torvalds March 14, 2020, 12:42 a.m. UTC | #1

On Fri, Mar 13, 2020 at 4:56 PM Al Viro <[e-mail]> wrote:
>
> -          !(flags & WALK_FOLLOW || nd->flags & LOOKUP_FOLLOW) ||
> -          flags & WALK_NOFOLLOW) {
> +          ((flags & WALK_TRAILING) && !(nd->flags & LOOKUP_FOLLOW)) ||
> +          (flags & WALK_NOFOLLOW)) {

Oh, and here you fix the implicit precedence thing I was complaining
about earlier.

Maybe my original complaint had happened at this point, and I'd missed
the original place.

Likely.

            Linus

Patch

diff --git a/fs/namei.c b/fs/namei.c
index 438717b462fb..5d25a3874a5b 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1819,7 +1819,7 @@  static const char *pick_link(struct nameidata *nd, struct path *link,
 	return NULL;
 }
 
-enum {WALK_FOLLOW = 1, WALK_MORE = 2, WALK_NOFOLLOW = 4};
+enum {WALK_TRAILING = 1, WALK_MORE = 2, WALK_NOFOLLOW = 4};
 
 /*
  * Do we need to follow links? We _really_ want to be able
@@ -1836,8 +1836,8 @@  static const char *step_into(struct nameidata *nd, int flags,
 	if (err < 0)
 		return ERR_PTR(err);
 	if (likely(!d_is_symlink(path.dentry)) ||
-	   !(flags & WALK_FOLLOW || nd->flags & LOOKUP_FOLLOW) ||
-	   flags & WALK_NOFOLLOW) {
+	   ((flags & WALK_TRAILING) && !(nd->flags & LOOKUP_FOLLOW)) ||
+	   (flags & WALK_NOFOLLOW)) {
 		/* not a symlink or should not follow */
 		path_to_nameidata(&path, nd);
 		nd->inode = inode;
@@ -2190,10 +2190,10 @@  static int link_path_walk(const char *name, struct nameidata *nd)
 			if (!name)
 				return 0;
 			/* last component of nested symlink */
-			link = walk_component(nd, WALK_FOLLOW);
+			link = walk_component(nd, 0);
 		} else {
 			/* not the last component */
-			link = walk_component(nd, WALK_FOLLOW | WALK_MORE);
+			link = walk_component(nd, WALK_MORE);
 		}
 		if (unlikely(link)) {
 			if (IS_ERR(link))
@@ -2321,7 +2321,7 @@  static inline const char *lookup_last(struct nameidata *nd)
 		nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
 
 	nd->flags &= ~LOOKUP_PARENT;
-	link = walk_component(nd, 0);
+	link = walk_component(nd, WALK_TRAILING);
 	if (link) {
 		nd->flags |= LOOKUP_PARENT;
 		nd->stack[0].name = NULL;
@@ -3276,7 +3276,7 @@  static const char *do_last(struct nameidata *nd,
 finish_lookup:
 	if (nd->depth)
 		put_link(nd);
-	res = step_into(nd, 0, dentry, inode, seq);
+	res = step_into(nd, WALK_TRAILING, dentry, inode, seq);
 	if (unlikely(res)) {
 		nd->flags |= LOOKUP_PARENT;
 		nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL);