Get rid of symlink body copying

Now that nd->last stays around until ->put_link() is called, we can
just postpone that ->put_link() in do_filp_open() a bit and don't
bother with copying.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 24 insertions, 31 deletions

diff --git a/fs/namei.c b/fs/namei.c
index adfbaf5c04a7..1f5d86d1fbf5 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -498,8 +498,6 @@ static int link_path_walk(const char *, struct nameidata *);
 
 static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *link)
 {
-        int res = 0;
-        char *name;
         if (IS_ERR(link))
                 goto fail;
 
@@ -510,22 +508,7 @@ static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *l
                 path_get(&nd->root);
         }
 
-        res = link_path_walk(link, nd);
-        if (nd->depth || res || nd->last_type!=LAST_NORM)
-                return res;
-        /*
-         * If it is an iterative symlinks resolution in open_namei() we
-         * have to copy the last component. And all that crap because of
-         * bloody create() on broken symlinks. Furrfu...
-         */
-        name = __getname();
-        if (unlikely(!name)) {
-                path_put(&nd->path);
-                return -ENOMEM;
-        }
-        strcpy(name, nd->last.name);
-        nd->last.name = name;
-        return 0;
+        return link_path_walk(link, nd);
 fail:
         path_put(&nd->path);
         return PTR_ERR(link);
@@ -547,10 +530,10 @@ static inline void path_to_nameidata(struct path *path, struct nameidata *nd)
         nd->path.dentry = path->dentry;
 }
 
-static __always_inline int __do_follow_link(struct path *path, struct nameidata *nd)
+static __always_inline int
+__do_follow_link(struct path *path, struct nameidata *nd, void **p)
 {
         int error;
-        void *cookie;
         struct dentry *dentry = path->dentry;
 
         touch_atime(path->mnt, dentry);
@@ -562,9 +545,9 @@ static __always_inline int __do_follow_link(struct path *path, struct nameidata
         }
         mntget(path->mnt);
         nd->last_type = LAST_BIND;
-        cookie = dentry->d_inode->i_op->follow_link(dentry, nd);
-        error = PTR_ERR(cookie);
-        if (!IS_ERR(cookie)) {
+        *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)
@@ -574,8 +557,6 @@ static __always_inline int __do_follow_link(struct path *path, struct nameidata
                         if (error)
                                 path_put(&nd->path);
                 }
-                if (dentry->d_inode->i_op->put_link)
-                        dentry->d_inode->i_op->put_link(dentry, nd, cookie);
         }
         return error;
 }
@@ -589,6 +570,7 @@ static __always_inline int __do_follow_link(struct path *path, struct nameidata
  */
 static inline int do_follow_link(struct path *path, struct nameidata *nd)
 {
+        void *cookie;
         int err = -ELOOP;
         if (current->link_count >= MAX_NESTED_LINKS)
                 goto loop;
@@ -602,7 +584,9 @@ static inline int do_follow_link(struct path *path, struct nameidata *nd)
         current->link_count++;
         current->total_link_count++;
         nd->depth++;
-        err = __do_follow_link(path, nd);
+        err = __do_follow_link(path, nd, &cookie);
+        if (!IS_ERR(cookie) && path->dentry->d_inode->i_op->put_link)
+                path->dentry->d_inode->i_op->put_link(path->dentry, nd, cookie);
         path_put(path);
         current->link_count--;
         nd->depth--;
@@ -1847,6 +1831,9 @@ reval:
                 nd.flags |= LOOKUP_EXCL;
         filp = do_last(&nd, &path, open_flag, acc_mode, mode, pathname);
         while (unlikely(!filp)) { /* trailing symlink */
+                struct path holder;
+                struct inode *inode;
+                void *cookie;
                 error = -ELOOP;
                 if ((open_flag & O_NOFOLLOW) || count++ == 32)
                         goto exit_dput;
@@ -1865,18 +1852,24 @@ reval:
                 error = security_inode_follow_link(path.dentry, &nd);
                 if (error)
                         goto exit_dput;
-                error = __do_follow_link(&path, &nd);
-                path_put(&path);
-                if (error) {
+                error = __do_follow_link(&path, &nd, &cookie);
+                if (unlikely(error)) {
                         /* nd.path had been dropped */
+                        inode = path.dentry->d_inode;
+                        if (!IS_ERR(cookie) && inode->i_op->put_link)
+                                inode->i_op->put_link(path.dentry, &nd, cookie);
+                        path_put(&path);
                         release_open_intent(&nd);
                         filp = ERR_PTR(error);
                         goto out;
                 }
+                holder = path;
                 nd.flags &= ~LOOKUP_PARENT;
                 filp = do_last(&nd, &path, open_flag, acc_mode, mode, pathname);
-                if (nd.last_type == LAST_NORM)
-                        __putname(nd.last.name);
+                inode = holder.dentry->d_inode;
+                if (inode->i_op->put_link)
+                        inode->i_op->put_link(holder.dentry, &nd, cookie);
+                path_put(&holder);
         }
 out:
         if (nd.root.mnt)