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namei.c: separate the parts of follow_link() that find the link body 

Split a piece of fs/namei.c:follow_link() that does obtaining the link
body into a separate function.  follow_link() itself is converted to
calling get_link() and then doing the body traversal (if any).

The next step will expand follow_link() call in link_path_walk()
and this helps to keep the size down...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2015-04-18 18:23:41 -04:00
parent 680baacbca
commit 0a959df54b
1 changed files with 36 additions and 29 deletions
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65
fs/namei.c
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@ -836,21 +836,22 @@ static int may_linkat(struct path *link)
return -EPERM;
}
static __always_inline int
follow_link(struct path *link, struct nameidata *nd, void **p)
static __always_inline const char *
get_link(struct path *link, struct nameidata *nd, void **p)
{
struct dentry *dentry = link->dentry;
struct inode *inode = dentry->d_inode;
int error;
const char *s;
const char *res;
BUG_ON(nd->flags & LOOKUP_RCU);
if (link->mnt == nd->path.mnt)
mntget(link->mnt);
error = -ELOOP;
res = ERR_PTR(-ELOOP);
if (unlikely(current->total_link_count >= 40))
goto out_put_nd_path;
goto out;
cond_resched();
current->total_link_count++;
@ -858,37 +859,43 @@ follow_link(struct path *link, struct nameidata *nd, void **p)
touch_atime(link);
error = security_inode_follow_link(dentry);
res = ERR_PTR(error);
if (error)
goto out_put_nd_path;
goto out;
nd->last_type = LAST_BIND;
*p = NULL;
s = dentry->d_inode->i_op->follow_link(dentry, p, nd);
error = PTR_ERR(s);
if (IS_ERR(s))
goto out_put_nd_path;
error = 0;
if (s) {
if (*s == '/') {
if (!nd->root.mnt)
set_root(nd);
path_put(&nd->path);
nd->path = nd->root;
path_get(&nd->root);
nd->flags |= LOOKUP_JUMPED;
}
nd->inode = nd->path.dentry->d_inode;
error = link_path_walk(s, nd);
if (unlikely(error))
put_link(nd, link, *p);
res = inode->i_op->follow_link(dentry, p, nd);
if (IS_ERR(res)) {
out:
path_put(&nd->path);
path_put(link);
}
return res;
}
return error;
static __always_inline int
follow_link(struct path *link, struct nameidata *nd, void **p)
{
const char *s = get_link(link, nd, p);
int error;
out_put_nd_path:
path_put(&nd->path);
path_put(link);
if (unlikely(IS_ERR(s)))
return PTR_ERR(s);
if (unlikely(!s))
return 0;
if (*s == '/') {
if (!nd->root.mnt)
set_root(nd);
path_put(&nd->path);
nd->path = nd->root;
path_get(&nd->root);
nd->flags |= LOOKUP_JUMPED;
}
nd->inode = nd->path.dentry->d_inode;
error = link_path_walk(s, nd);
if (unlikely(error))
put_link(nd, link, *p);
return error;
}