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namei.c: let follow_link() do put_link() on failure

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no need for kludgy "set cookie to ERR_PTR(...) because we failed
before we did actual ->follow_link() and want to suppress put_link()",
no pointless check in put_link() itself.

Callers checked if follow_link() has failed anyway; might as well
break out of their loops if that happened, without bothering
to call put_link() first.

[AV: folded fixes from hch]

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2012-06-10 04:15:17 -04:00
parent 1d674107ea
commit 6d7b5aaed7
1 changed files with 41 additions and 33 deletions
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74
fs/namei.c
View file

@ -605,7 +605,7 @@ static inline void path_to_nameidata(const struct path *path,
static inline void put_link(struct nameidata *nd, struct path *link, void *cookie)
{
struct inode *inode = link->dentry->d_inode;
if (!IS_ERR(cookie) && inode->i_op->put_link)
if (inode->i_op->put_link)
inode->i_op->put_link(link->dentry, nd, cookie);
path_put(link);
}
@ -613,19 +613,19 @@ static inline void put_link(struct nameidata *nd, struct path *link, void *cooki
static __always_inline int
follow_link(struct path *link, struct nameidata *nd, void **p)
{
int error;
struct dentry *dentry = link->dentry;
int error;
char *s;
BUG_ON(nd->flags & LOOKUP_RCU);
if (link->mnt == nd->path.mnt)
mntget(link->mnt);
if (unlikely(current->total_link_count >= 40)) {
*p = ERR_PTR(-ELOOP); /* no ->put_link(), please */
path_put(&nd->path);
return -ELOOP;
}
error = -ELOOP;
if (unlikely(current->total_link_count >= 40))
goto out_put_nd_path;
cond_resched();
current->total_link_count++;
@ -633,30 +633,37 @@ follow_link(struct path *link, struct nameidata *nd, void **p)
nd_set_link(nd, NULL);
error = security_inode_follow_link(link->dentry, nd);
if (error) {
*p = ERR_PTR(error); /* no ->put_link(), please */
path_put(&nd->path);
return error;
}
if (error)
goto out_put_nd_path;
nd->last_type = LAST_BIND;
*p = dentry->d_inode->i_op->follow_link(dentry, nd);
error = PTR_ERR(*p);
if (!IS_ERR(*p)) {
char *s = nd_get_link(nd);
error = 0;
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 (IS_ERR(*p))
goto out_put_link;
error = 0;
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);
return error;
out_put_nd_path:
path_put(&nd->path);
out_put_link:
path_put(link);
return error;
}
@ -1383,9 +1390,10 @@ static inline int nested_symlink(struct path *path, struct nameidata *nd)
void *cookie;
res = follow_link(&link, nd, &cookie);
if (!res)
res = walk_component(nd, path, &nd->last,
nd->last_type, LOOKUP_FOLLOW);
if (res)
break;
res = walk_component(nd, path, &nd->last,
nd->last_type, LOOKUP_FOLLOW);
put_link(nd, &link, cookie);
} while (res > 0);
@ -1777,8 +1785,9 @@ static int path_lookupat(int dfd, const char *name,
struct path link = path;
nd->flags |= LOOKUP_PARENT;
err = follow_link(&link, nd, &cookie);
if (!err)
err = lookup_last(nd, &path);
if (err)
break;
err = lookup_last(nd, &path);
put_link(nd, &link, cookie);
}
}
@ -2475,9 +2484,8 @@ static struct file *path_openat(int dfd, const char *pathname,
nd->flags &= ~(LOOKUP_OPEN|LOOKUP_CREATE|LOOKUP_EXCL);
error = follow_link(&link, nd, &cookie);
if (unlikely(error))
filp = ERR_PTR(error);
else
filp = do_last(nd, &path, op, pathname);
goto out_filp;
filp = do_last(nd, &path, op, pathname);
put_link(nd, &link, cookie);
}
out: