[RFC][PATCH v4 59/69] pick_link(): take reserving space on stack into a new helper

Al Viro
2020-03-13T23:55:15Z

fs/namei.c | 46 +++++++++++++++++++++++++---------------------
1 file changed, 25 insertions(+), 21 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index d58e447db2f1..c27f657c6b71 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1580,6 +1580,28 @@ static inline int may_lookup(struct nameidata *nd)
return inode_permission(nd->inode, MAY_EXEC);
}

+static int reserve_stack(struct nameidata *nd, struct path *link, unsigned seq)
+{
+ int error;
+
+ if (unlikely(nd->total_link_count++ >= MAXSYMLINKS))
+ return -ELOOP;
+ error = nd_alloc_stack(nd);
+ if (likely(!error))
+ return 0;
+ if (error == -ECHILD) {
+ // we must grab link first
+ bool grabbed_link = legitimize_path(nd, link, seq);
+ // ... and we must unlazy to be able to clean up
+ error = unlazy_walk(nd);
+ if (unlikely(!grabbed_link))
+ error = -ECHILD;
+ if (!error)
+ error = nd_alloc_stack(nd);
+ }
+ return error;
+}
+
enum {WALK_TRAILING = 1, WALK_MORE = 2, WALK_NOFOLLOW = 4};

static const char *pick_link(struct nameidata *nd, struct path *link,
@@ -1587,31 +1609,13 @@ static const char *pick_link(struct nameidata *nd, struct path *link,
{
struct saved *last;
const char *res;
- int error;
+ int error = reserve_stack(nd, link, seq);

- if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) {
- if (!(nd->flags & LOOKUP_RCU))
- path_put(link);
- return ERR_PTR(-ELOOP);
- }
- error = nd_alloc_stack(nd);
if (unlikely(error)) {
- if (error == -ECHILD) {
- // we must grab link first
- bool grabbed_link = legitimize_path(nd, link, seq);
- // ... and we must unlazy to be able to clean up
- error = unlazy_walk(nd);
- if (unlikely(!grabbed_link))
- error = -ECHILD;
- if (!error)
- error = nd_alloc_stack(nd);
- }
- if (error) {
+ if (!(nd->flags & LOOKUP_RCU))
path_put(link);
- return ERR_PTR(error);
- }
+ return ERR_PTR(error);
}
-
last = nd->stack + nd->depth++;
last->link = *link;
clear_delayed_call(&last->done);
--
2.11.0