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fs: add nd_jump_link 

Add a helper that abstracts out the jump to an already parsed struct path
from ->follow_link operation from procfs.  Not only does this clean up
the code by moving the two sides of this game into a single helper, but
it also prepares for making struct nameidata private to namei.c

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Christoph Hellwig 2012-06-18 10:47:04 -04:00 committed by Al Viro
parent 408ef013cc
commit b5fb63c183
3 changed files with 20 additions and 12 deletions
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27
fs/namei.c
View File

@ -586,6 +586,21 @@ static inline void path_to_nameidata(const struct path *path,
nd->path.dentry = path->dentry;
}
/*
* Helper to directly jump to a known parsed path from ->follow_link,
* caller must have taken a reference to path beforehand.
*/
void nd_jump_link(struct nameidata *nd, struct path *path)
{
path_put(&nd->path);
nd->path = *path;
nd->inode = nd->path.dentry->d_inode;
nd->flags |= LOOKUP_JUMPED;
BUG_ON(nd->inode->i_op->follow_link);
}
static inline void put_link(struct nameidata *nd, struct path *link, void *cookie)
{
struct inode *inode = link->dentry->d_inode;
@ -630,17 +645,9 @@ follow_link(struct path *link, struct nameidata *nd, void **p)
s = nd_get_link(nd);
if (s) {
error = __vfs_follow_link(nd, s);
} else if (nd->last_type == LAST_BIND) {
nd->flags |= LOOKUP_JUMPED;
nd->inode = nd->path.dentry->d_inode;
if (nd->inode->i_op->follow_link) {
/* stepped on a _really_ weird one */
path_put(&nd->path);
error = -ELOOP;
}
if (unlikely(error))
put_link(nd, link, *p);
}
if (unlikely(error))
put_link(nd, link, *p);
return error;

3
fs/proc/base.c
View File

@ -1438,8 +1438,7 @@ static void *proc_pid_follow_link(struct dentry *dentry, struct nameidata *nd)
if (error)
goto out;
path_put(&nd->path);
nd->path = path;
nd_jump_link(nd, &path);
return NULL;
out:
return ERR_PTR(error);

2
include/linux/namei.h
View File

@ -80,6 +80,8 @@ extern int follow_up(struct path *);
extern struct dentry *lock_rename(struct dentry *, struct dentry *);
extern void unlock_rename(struct dentry *, struct dentry *);
extern void nd_jump_link(struct nameidata *nd, struct path *path);
static inline void nd_set_link(struct nameidata *nd, char *path)
{
nd->saved_names[nd->depth] = path;