[RFC][PATCH v4 15/69] new step_into() flag: WALK_NOFOLLOW

Al Viro
2020-03-13T23:57:56Z

Tells step_into() not to follow symlinks, regardless of LOOKUP_FOLLOW.
Allows to switch handle_lookup_down() to of step_into(), getting
all follow_managed() and step_into() calls paired.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/namei.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 3097edcb4a1a..e47b376cf442 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1827,7 +1827,7 @@ static int pick_link(struct nameidata *nd, struct path *link,
return 1;
}

-enum {WALK_FOLLOW = 1, WALK_MORE = 2};
+enum {WALK_FOLLOW = 1, WALK_MORE = 2, WALK_NOFOLLOW = 4};

/*
* Do we need to follow links? We _really_ want to be able
@@ -1839,7 +1839,8 @@ static inline int step_into(struct nameidata *nd, struct path *path,
int flags, struct inode *inode, unsigned seq)
{
if (likely(!d_is_symlink(path->dentry)) ||
- !(flags & WALK_FOLLOW || nd->flags & LOOKUP_FOLLOW)) {
+ !(flags & WALK_FOLLOW || nd->flags & LOOKUP_FOLLOW) ||
+ flags & WALK_NOFOLLOW) {
/* not a symlink or should not follow */
path_to_nameidata(path, nd);
nd->inode = inode;
@@ -2363,10 +2364,7 @@ static int handle_lookup_down(struct nameidata *nd)
err = handle_mounts(nd, nd->path.dentry, &path, &inode, &seq);
if (unlikely(err < 0))
return err;
- path_to_nameidata(&path, nd);
- nd->inode = inode;
- nd->seq = seq;
- return 0;
+ return step_into(nd, &path, WALK_NOFOLLOW, inode, seq);
}

/* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
--
2.11.0