[RFC][PATCH v3 24/55] finally fold get_link() into pick_link()

Al Viro
2020-03-01T21:55:10Z

kill nd->link_inode, while we are at it

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/namei.c | 135 ++++++++++++++++++++++++++++---------------------------------
1 file changed, 61 insertions(+), 74 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index fef2c447219d..9b6c3e3edd75 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -503,7 +503,6 @@ struct nameidata {
} *stack, internal[EMBEDDED_LEVELS];
struct filename *name;
struct nameidata *saved;
- struct inode *link_inode;
unsigned root_seq;
int dfd;
} __randomize_layout;
@@ -962,9 +961,8 @@ int sysctl_protected_regular __read_mostly;
*
* Returns 0 if following the symlink is allowed, -ve on error.
*/
-static inline int may_follow_link(struct nameidata *nd)
+static inline int may_follow_link(struct nameidata *nd, const struct inode *inode)
{
- const struct inode *inode;
const struct inode *parent;
kuid_t puid;

@@ -972,7 +970,6 @@ static inline int may_follow_link(struct nameidata *nd)
return 0;

/* Allowed if owner and follower match. */
- inode = nd->link_inode;
if (uid_eq(current_cred()->fsuid, inode->i_uid))
return 0;

@@ -1106,73 +1103,6 @@ static int may_create_in_sticky(umode_t dir_mode, kuid_t dir_uid,
return 0;
}

-static __always_inline
-const char *get_link(struct nameidata *nd)
-{
- struct saved *last = nd->stack + nd->depth - 1;
- struct dentry *dentry = last->link.dentry;
- struct inode *inode = nd->link_inode;
- int error;
- const char *res;
-
- if (!(nd->flags & LOOKUP_PARENT)) {
- error = may_follow_link(nd);
- if (unlikely(error))
- return ERR_PTR(error);
- }
-
- if (unlikely(nd->flags & LOOKUP_NO_SYMLINKS))
- return ERR_PTR(-ELOOP);
-
- if (!(nd->flags & LOOKUP_RCU)) {
- touch_atime(&last->link);
- cond_resched();
- } else if (atime_needs_update(&last->link, inode)) {
- if (unlikely(unlazy_walk(nd)))
- return ERR_PTR(-ECHILD);
- touch_atime(&last->link);
- }
-
- error = security_inode_follow_link(dentry, inode,
- nd->flags & LOOKUP_RCU);
- if (unlikely(error))
- return ERR_PTR(error);
-
- nd->last_type = LAST_BIND;
- res = READ_ONCE(inode->i_link);
- if (!res) {
- const char * (*get)(struct dentry *, struct inode *,
- struct delayed_call *);
- get = inode->i_op->get_link;
- if (nd->flags & LOOKUP_RCU) {
- res = get(NULL, inode, &last->done);
- if (res == ERR_PTR(-ECHILD)) {
- if (unlikely(unlazy_walk(nd)))
- return ERR_PTR(-ECHILD);
- res = get(dentry, inode, &last->done);
- }
- } else {
- res = get(dentry, inode, &last->done);
- }
- if (!res)
- goto all_done;
- if (IS_ERR(res))
- return res;
- }
- if (*res == '/') {
- error = nd_jump_root(nd);
- if (unlikely(error))
- return ERR_PTR(error);
- while (unlikely(*++res == '/'))
- ;
- }
- if (*res)
- return res;
-all_done: // pure jump
- put_link(nd);
- return NULL;
-}
-
/*
* follow_up - Find the mountpoint of path's vfsmount
*
@@ -1796,8 +1726,10 @@ static inline int handle_dots(struct nameidata *nd, int type)
static const char *pick_link(struct nameidata *nd, struct path *link,
struct inode *inode, unsigned seq)
{
- int error;
struct saved *last;
+ const char *res;
+ int error;
+
if (unlikely(nd->total_link_count++ >= MAXSYMLINKS)) {
path_to_nameidata(link, nd);
return ERR_PTR(-ELOOP);
@@ -1828,9 +1760,64 @@ static const char *pick_link(struct nameidata *nd, struct path *link,
last = nd->stack + nd->depth++;
last->link = *link;
clear_delayed_call(&last->done);
- nd->link_inode = inode;
last->seq = seq;
- return get_link(nd);
+
+ if (!(nd->flags & LOOKUP_PARENT)) {
+ error = may_follow_link(nd, inode);
+ if (unlikely(error))
+ return ERR_PTR(error);
+ }
+
+ if (unlikely(nd->flags & LOOKUP_NO_SYMLINKS))
+ return ERR_PTR(-ELOOP);
+
+ if (!(nd->flags & LOOKUP_RCU)) {
+ touch_atime(&last->link);
+ cond_resched();
+ } else if (atime_needs_update(&last->link, inode)) {
+ if (unlikely(unlazy_walk(nd)))
+ return ERR_PTR(-ECHILD);
+ touch_atime(&last->link);
+ }
+
+ error = security_inode_follow_link(link->dentry, inode,
+ nd->flags & LOOKUP_RCU);
+ if (unlikely(error))
+ return ERR_PTR(error);
+
+ nd->last_type = LAST_BIND;
+ res = READ_ONCE(inode->i_link);
+ if (!res) {
+ const char * (*get)(struct dentry *, struct inode *,
+ struct delayed_call *);
+ get = inode->i_op->get_link;
+ if (nd->flags & LOOKUP_RCU) {
+ res = get(NULL, inode, &last->done);
+ if (res == ERR_PTR(-ECHILD)) {
+ if (unlikely(unlazy_walk(nd)))
+ return ERR_PTR(-ECHILD);
+ res = get(link->dentry, inode, &last->done);
+ }
+ } else {
+ res = get(link->dentry, inode, &last->done);
+ }
+ if (!res)
+ goto all_done;
+ if (IS_ERR(res))
+ return res;
+ }
+ if (*res == '/') {
+ error = nd_jump_root(nd);
+ if (unlikely(error))
+ return ERR_PTR(error);
+ while (unlikely(*++res == '/'))
+ ;
+ }
+ if (*res)
+ return res;
+all_done: // pure jump
+ put_link(nd);
+ return NULL;
}

enum {WALK_FOLLOW = 1, WALK_MORE = 2, WALK_NOFOLLOW = 4};
--
2.11.0