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Subject[PATCH v3 106/110] namei: don't unlazy until get_link()
Date
From: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/namei.c | 37 ++++++++++++++++++++++++++-----------
1 file changed, 26 insertions(+), 11 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 090214b..4d6065d 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -536,10 +536,19 @@ static void restore_nameidata(struct nameidata *old)

static int __nd_alloc_stack(struct nameidata *nd)
{
- struct saved *p = kmalloc(MAXSYMLINKS * sizeof(struct saved),
+ struct saved *p;
+
+ if (nd->flags & LOOKUP_RCU) {
+ p= kmalloc(MAXSYMLINKS * sizeof(struct saved),
+ GFP_ATOMIC);
+ if (unlikely(!p))
+ return -ECHILD;
+ } else {
+ p= kmalloc(MAXSYMLINKS * sizeof(struct saved),
GFP_KERNEL);
- if (unlikely(!p))
- return -ENOMEM;
+ if (unlikely(!p))
+ return -ENOMEM;
+ }
memcpy(p, nd->internal, sizeof(nd->internal));
nd->stack = p;
return 0;
@@ -949,8 +958,10 @@ const char *get_link(struct nameidata *nd)
int error;
const char *res;

- BUG_ON(nd->flags & LOOKUP_RCU);
-
+ if (nd->flags & LOOKUP_RCU) {
+ if (unlikely(unlazy_walk(nd, NULL, 0)))
+ return ERR_PTR(-ECHILD);
+ }
cond_resched();

touch_atime(&last->link);
@@ -1632,17 +1643,21 @@ static int pick_link(struct nameidata *nd, struct path *link,
path_to_nameidata(link, nd);
return -ELOOP;
}
- if (nd->flags & LOOKUP_RCU) {
- if (unlikely(unlazy_link(nd, link, seq)))
- return -ECHILD;
- } else {
+ if (!(nd->flags & LOOKUP_RCU)) {
if (link->mnt == nd->path.mnt)
mntget(link->mnt);
}
error = nd_alloc_stack(nd);
if (unlikely(error)) {
- path_put(link);
- return error;
+ if (error == -ECHILD) {
+ if (unlikely(unlazy_link(nd, link, seq)))
+ return -ECHILD;
+ error = nd_alloc_stack(nd);
+ }
+ if (error) {
+ path_put(link);
+ return error;
+ }
}

last = nd->stack + nd->depth++;
--
2.1.4


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