[PATCH] new (local) helper: user_path_parent()

Preparation to untangling intents mess: reduce the number of do_path_lookup()
callers.

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

1 files changed, 57 insertions, 80 deletions

diff --git a/fs/namei.c b/fs/namei.c
index edb5e973f9b3..38ceb6e06eba 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1352,6 +1352,24 @@ int user_path_at(int dfd, const char __user *name, unsigned flags,
         return err;
 }
 
+static int user_path_parent(int dfd, const char __user *path,
+                        struct nameidata *nd, char **name)
+{
+        char *s = getname(path);
+        int error;
+
+        if (IS_ERR(s))
+                return PTR_ERR(s);
+
+        error = do_path_lookup(dfd, s, LOOKUP_PARENT, nd);
+        if (error)
+                putname(s);
+        else
+                *name = s;
+
+        return error;
+}
+
 /*
  * It's inline, so penalty for filesystems that don't use sticky bit is
  * minimal.
@@ -1989,20 +2007,18 @@ static int may_mknod(mode_t mode)
 asmlinkage long sys_mknodat(int dfd, const char __user *filename, int mode,
                                 unsigned dev)
 {
-        int error = 0;
-        char * tmp;
-        struct dentry * dentry;
+        int error;
+        char *tmp;
+        struct dentry *dentry;
         struct nameidata nd;
 
         if (S_ISDIR(mode))
                 return -EPERM;
-        tmp = getname(filename);
-        if (IS_ERR(tmp))
-                return PTR_ERR(tmp);
 
-        error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd);
+        error = user_path_parent(dfd, filename, &nd, &tmp);
         if (error)
-                goto out;
+                return error;
+
         dentry = lookup_create(&nd, 0);
         if (IS_ERR(dentry)) {
                 error = PTR_ERR(dentry);
@@ -2034,7 +2050,6 @@ out_dput:
 out_unlock:
         mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
         path_put(&nd.path);
-out:
         putname(tmp);
 
         return error;
@@ -2074,14 +2089,10 @@ asmlinkage long sys_mkdirat(int dfd, const char __user *pathname, int mode)
         struct dentry *dentry;
         struct nameidata nd;
 
-        tmp = getname(pathname);
-        error = PTR_ERR(tmp);
-        if (IS_ERR(tmp))
+        error = user_path_parent(dfd, pathname, &nd, &tmp);
+        if (error)
                 goto out_err;
 
-        error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd);
-        if (error)
-                goto out;
         dentry = lookup_create(&nd, 1);
         error = PTR_ERR(dentry);
         if (IS_ERR(dentry))
@@ -2099,7 +2110,6 @@ out_dput:
 out_unlock:
         mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
         path_put(&nd.path);
-out:
         putname(tmp);
 out_err:
         return error;
@@ -2177,13 +2187,9 @@ static long do_rmdir(int dfd, const char __user *pathname)
         struct dentry *dentry;
         struct nameidata nd;
 
-        name = getname(pathname);
-        if(IS_ERR(name))
-                return PTR_ERR(name);
-
-        error = do_path_lookup(dfd, name, LOOKUP_PARENT, &nd);
+        error = user_path_parent(dfd, pathname, &nd, &name);
         if (error)
-                goto exit;
+                return error;
 
         switch(nd.last_type) {
                 case LAST_DOTDOT:
@@ -2212,7 +2218,6 @@ exit2:
         mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
 exit1:
         path_put(&nd.path);
-exit:
         putname(name);
         return error;
 }
@@ -2261,19 +2266,16 @@ int vfs_unlink(struct inode *dir, struct dentry *dentry)
  */
 static long do_unlinkat(int dfd, const char __user *pathname)
 {
-        int error = 0;
-        char * name;
+        int error;
+        char *name;
         struct dentry *dentry;
         struct nameidata nd;
         struct inode *inode = NULL;
 
-        name = getname(pathname);
-        if(IS_ERR(name))
-                return PTR_ERR(name);
-
-        error = do_path_lookup(dfd, name, LOOKUP_PARENT, &nd);
+        error = user_path_parent(dfd, pathname, &nd, &name);
         if (error)
-                goto exit;
+                return error;
+
         error = -EISDIR;
         if (nd.last_type != LAST_NORM)
                 goto exit1;
@@ -2300,7 +2302,6 @@ static long do_unlinkat(int dfd, const char __user *pathname)
                 iput(inode);    /* truncate the inode here */
 exit1:
         path_put(&nd.path);
-exit:
         putname(name);
         return error;
 
@@ -2350,23 +2351,20 @@ int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname)
 asmlinkage long sys_symlinkat(const char __user *oldname,
                               int newdfd, const char __user *newname)
 {
-        int error = 0;
-        char * from;
-        char * to;
+        int error;
+        char *from;
+        char *to;
         struct dentry *dentry;
         struct nameidata nd;
 
         from = getname(oldname);
-        if(IS_ERR(from))
+        if (IS_ERR(from))
                 return PTR_ERR(from);
-        to = getname(newname);
-        error = PTR_ERR(to);
-        if (IS_ERR(to))
-                goto out_putname;
 
-        error = do_path_lookup(newdfd, to, LOOKUP_PARENT, &nd);
+        error = user_path_parent(newdfd, newname, &nd, &to);
         if (error)
-                goto out;
+                goto out_putname;
+
         dentry = lookup_create(&nd, 0);
         error = PTR_ERR(dentry);
         if (IS_ERR(dentry))
@@ -2382,7 +2380,6 @@ out_dput:
 out_unlock:
         mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
         path_put(&nd.path);
-out:
         putname(to);
 out_putname:
         putname(from);
@@ -2449,21 +2446,18 @@ asmlinkage long sys_linkat(int olddfd, const char __user *oldname,
         struct nameidata nd;
         struct path old_path;
         int error;
-        char * to;
+        char *to;
 
         if ((flags & ~AT_SYMLINK_FOLLOW) != 0)
                 return -EINVAL;
 
-        to = getname(newname);
-        if (IS_ERR(to))
-                return PTR_ERR(to);
-
         error = user_path_at(olddfd, oldname,
                              flags & AT_SYMLINK_FOLLOW ? LOOKUP_FOLLOW : 0,
                              &old_path);
         if (error)
-                goto exit;
-        error = do_path_lookup(newdfd, to, LOOKUP_PARENT, &nd);
+                return error;
+
+        error = user_path_parent(newdfd, newname, &nd, &to);
         if (error)
                 goto out;
         error = -EXDEV;
@@ -2484,10 +2478,9 @@ out_unlock:
         mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
 out_release:
         path_put(&nd.path);
+        putname(to);
 out:
         path_put(&old_path);
-exit:
-        putname(to);
 
         return error;
 }
@@ -2643,20 +2636,22 @@ int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
         return error;
 }
 
-static int do_rename(int olddfd, const char *oldname,
-                        int newdfd, const char *newname)
+asmlinkage long sys_renameat(int olddfd, const char __user *oldname,
+                             int newdfd, const char __user *newname)
 {
-        int error = 0;
-        struct dentry * old_dir, * new_dir;
-        struct dentry * old_dentry, *new_dentry;
-        struct dentry * trap;
+        struct dentry *old_dir, *new_dir;
+        struct dentry *old_dentry, *new_dentry;
+        struct dentry *trap;
         struct nameidata oldnd, newnd;
+        char *from;
+        char *to;
+        int error;
 
-        error = do_path_lookup(olddfd, oldname, LOOKUP_PARENT, &oldnd);
+        error = user_path_parent(olddfd, oldname, &oldnd, &from);
         if (error)
                 goto exit;
 
-        error = do_path_lookup(newdfd, newname, LOOKUP_PARENT, &newnd);
+        error = user_path_parent(newdfd, newname, &newnd, &to);
         if (error)
                 goto exit1;
 
@@ -2718,29 +2713,11 @@ exit3:
         unlock_rename(new_dir, old_dir);
 exit2:
         path_put(&newnd.path);
+        putname(to);
 exit1:
         path_put(&oldnd.path);
-exit:
-        return error;
-}
-
-asmlinkage long sys_renameat(int olddfd, const char __user *oldname,
-                             int newdfd, const char __user *newname)
-{
-        int error;
-        char * from;
-        char * to;
-
-        from = getname(oldname);
-        if(IS_ERR(from))
-                return PTR_ERR(from);
-        to = getname(newname);
-        error = PTR_ERR(to);
-        if (!IS_ERR(to)) {
-                error = do_rename(olddfd, from, newdfd, to);
-                putname(to);
-        }
         putname(from);
+exit:
         return error;
 }