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Subject[PATCH 3/4] teach set_nameidata() to handle setting the root as well
Date
That way we don't need the callers to mess with manually setting any fields
of nameidata instances. Old set_nameidata() gets renamed (__set_nameidata()),
new becomes an inlined helper that takes a struct path pointer and deals
with setting nd->root and putting ND_ROOT_PRESET in nd->state when new
argument is non-NULL.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/namei.c | 28 ++++++++++++++++------------
1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 622b9f15bf1c..40ffb249aa7f 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -577,7 +577,7 @@ struct nameidata {
#define ND_ROOT_GRABBED 2
#define ND_JUMPED 4

-static void set_nameidata(struct nameidata *p, int dfd, struct filename *name)
+static void __set_nameidata(struct nameidata *p, int dfd, struct filename *name)
{
struct nameidata *old = current->nameidata;
p->stack = p->internal;
@@ -587,10 +587,20 @@ static void set_nameidata(struct nameidata *p, int dfd, struct filename *name)
p->path.dentry = NULL;
p->total_link_count = old ? old->total_link_count : 0;
p->saved = old;
- p->state = 0;
current->nameidata = p;
}

+static inline void set_nameidata(struct nameidata *p, int dfd, struct filename *name,
+ const struct path *root)
+{
+ __set_nameidata(p, dfd, name);
+ p->state = 0;
+ if (unlikely(root)) {
+ p->state = ND_ROOT_PRESET;
+ p->root = *root;
+ }
+}
+
static void restore_nameidata(void)
{
struct nameidata *now = current->nameidata, *old = now->saved;
@@ -2454,11 +2464,7 @@ int filename_lookup(int dfd, struct filename *name, unsigned flags,
struct nameidata nd;
if (IS_ERR(name))
return PTR_ERR(name);
- set_nameidata(&nd, dfd, name);
- if (unlikely(root)) {
- nd.root = *root;
- nd.state = ND_ROOT_PRESET;
- }
+ set_nameidata(&nd, dfd, name, root);
retval = path_lookupat(&nd, flags | LOOKUP_RCU, path);
if (unlikely(retval == -ECHILD))
retval = path_lookupat(&nd, flags, path);
@@ -2499,7 +2505,7 @@ static struct filename *filename_parentat(int dfd, struct filename *name,

if (IS_ERR(name))
return name;
- set_nameidata(&nd, dfd, name);
+ set_nameidata(&nd, dfd, name, NULL);
retval = path_parentat(&nd, flags | LOOKUP_RCU, parent);
if (unlikely(retval == -ECHILD))
retval = path_parentat(&nd, flags, parent);
@@ -3530,7 +3536,7 @@ struct file *do_filp_open(int dfd, struct filename *pathname,
int flags = op->lookup_flags;
struct file *filp;

- set_nameidata(&nd, dfd, pathname);
+ set_nameidata(&nd, dfd, pathname, NULL);
filp = path_openat(&nd, op, flags | LOOKUP_RCU);
if (unlikely(filp == ERR_PTR(-ECHILD)))
filp = path_openat(&nd, op, flags);
@@ -3555,9 +3561,7 @@ struct file *do_file_open_root(const struct path *root,
if (IS_ERR(filename))
return ERR_CAST(filename);

- set_nameidata(&nd, -1, filename);
- nd.root = *root;
- nd.state = ND_ROOT_PRESET;
+ set_nameidata(&nd, -1, filename, root);
file = path_openat(&nd, op, flags | LOOKUP_RCU);
if (unlikely(file == ERR_PTR(-ECHILD)))
file = path_openat(&nd, op, flags);
--
2.11.0
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