[RFC][PATCH v4 61/69] __nd_alloc_stack(): make it return bool

Al Viro
2020-03-13T23:55:29Z

... and adjust the caller (reserve_stack()). Rename to nd_alloc_stack(),
while we are at it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/namei.c | 45 ++++++++++++++++++---------------------------
1 file changed, 18 insertions(+), 27 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 01ffbc58e761..c4b6e3c969b7 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -529,24 +529,17 @@ static void restore_nameidata(void)
kfree(now->stack);
}

-static int __nd_alloc_stack(struct nameidata *nd)
+static bool nd_alloc_stack(struct nameidata *nd)
{
struct saved *p;

- if (nd->flags & LOOKUP_RCU) {
- p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved),
- GFP_ATOMIC);
- if (unlikely(!p))
- return -ECHILD;
- } else {
- p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved),
- GFP_KERNEL);
- if (unlikely(!p))
- return -ENOMEM;
- }
+ p= kmalloc_array(MAXSYMLINKS, sizeof(struct saved),
+ nd->flags & LOOKUP_RCU ? GFP_ATOMIC : GFP_KERNEL);
+ if (unlikely(!p))
+ return false;
memcpy(p, nd->internal, sizeof(nd->internal));
nd->stack = p;
- return 0;
+ return true;
}

/**
@@ -1573,8 +1566,6 @@ static inline int may_lookup(struct nameidata *nd)

static int reserve_stack(struct nameidata *nd, struct path *link, unsigned seq)
{
- int error;
-
if (unlikely(nd->total_link_count++ >= MAXSYMLINKS))
return -ELOOP;

@@ -1582,21 +1573,21 @@ static int reserve_stack(struct nameidata *nd, struct path *link, unsigned seq)
return 0;
if (likely(nd->stack != nd->internal))
return 0;
-
- error = __nd_alloc_stack(nd);
- if (likely(!error))
+ if (likely(nd_alloc_stack(nd)))
return 0;
- if (error == -ECHILD) {
- // we must grab link first
+
+ if (nd->flags & LOOKUP_RCU) {
+ // we need to grab link before we do unlazy. And we can't skip
+ // unlazy even if we fail to grab the link - cleanup needs it
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 (unlazy_walk(nd) != 0 || !grabbed_link)
+ return -ECHILD;
+
+ if (nd_alloc_stack(nd))
+ return 0;
}
- return error;
+ return -ENOMEM;
}

enum {WALK_TRAILING = 1, WALK_MORE = 2, WALK_NOFOLLOW = 4};
--
2.11.0