[PATCH] knfsd: reduce stack consumption

[linux.git] / fs / namei.c

diff --git a/fs/namei.c b/fs/namei.c
index c5769c4fcab185ea1996e947c5b910abfd155dd5..6dbbd42d8b95fb933ed7a4f3e0183baff73fe3fb 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -256,6 +256,38 @@ int permission(struct inode *inode, int mask, struct nameidata *nd)
        return security_inode_permission(inode, mask, nd);
 }
 
+/**
+ * vfs_permission  -  check for access rights to a given path
+ * @nd:                lookup result that describes the path
+ * @mask:      right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
+ *
+ * Used to check for read/write/execute permissions on a path.
+ * We use "fsuid" for this, letting us set arbitrary permissions
+ * for filesystem access without changing the "normal" uids which
+ * are used for other things.
+ */
+int vfs_permission(struct nameidata *nd, int mask)
+{
+       return permission(nd->dentry->d_inode, mask, nd);
+}
+
+/**
+ * file_permission  -  check for additional access rights to a given file
+ * @file:      file to check access rights for
+ * @mask:      right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
+ *
+ * Used to check for read/write/execute permissions on an already opened
+ * file.
+ *
+ * Note:
+ *     Do not use this function in new code.  All access checks should
+ *     be done using vfs_permission().
+ */
+int file_permission(struct file *file, int mask)
+{
+       return permission(file->f_dentry->d_inode, mask, NULL);
+}
+
 /*
  * get_write_access() gets write permission for a file.
  * put_write_access() releases this write permission.
@@ -765,9 +797,8 @@ static fastcall int __link_path_walk(const char * name, struct nameidata *nd)
 
                nd->flags |= LOOKUP_CONTINUE;
                err = exec_permission_lite(inode, nd);
-               if (err == -EAGAIN) { 
-                       err = permission(inode, MAY_EXEC, nd);
-               }
+               if (err == -EAGAIN)
+                       err = vfs_permission(nd, MAY_EXEC);
                if (err)
                        break;
 
@@ -1109,8 +1140,9 @@ int path_lookup_open(const char *name, unsigned int lookup_flags,
  * @open_flags: open intent flags
  * @create_mode: create intent flags
  */
-int path_lookup_create(const char *name, unsigned int lookup_flags,
-               struct nameidata *nd, int open_flags, int create_mode)
+static int path_lookup_create(const char *name, unsigned int lookup_flags,
+                             struct nameidata *nd, int open_flags,
+                             int create_mode)
 {
        return __path_lookup_intent_open(name, lookup_flags|LOOKUP_CREATE, nd,
                        open_flags, create_mode);
@@ -1173,9 +1205,9 @@ out:
        return dentry;
 }
 
-struct dentry * lookup_hash(struct qstr *name, struct dentry * base)
+struct dentry * lookup_hash(struct nameidata *nd)
 {
-       return __lookup_hash(name, base, NULL);
+       return __lookup_hash(&nd->last, nd->dentry, nd);
 }
 
 /* SMP-safe */
@@ -1199,7 +1231,7 @@ struct dentry * lookup_one_len(const char * name, struct dentry * base, int len)
        }
        this.hash = end_name_hash(hash);
 
-       return lookup_hash(&this, base);
+       return __lookup_hash(&this, base, NULL);
 access:
        return ERR_PTR(-EACCES);
 }
@@ -1407,7 +1439,7 @@ int may_open(struct nameidata *nd, int acc_mode, int flag)
        if (S_ISDIR(inode->i_mode) && (flag & FMODE_WRITE))
                return -EISDIR;
 
-       error = permission(inode, acc_mode, nd);
+       error = vfs_permission(nd, acc_mode);
        if (error)
                return error;
 
@@ -1459,7 +1491,7 @@ int may_open(struct nameidata *nd, int acc_mode, int flag)
                if (!error) {
                        DQUOT_INIT(inode);
                        
-                       error = do_truncate(dentry, 0);
+                       error = do_truncate(dentry, 0, NULL);
                }
                put_write_access(inode);
                if (error)
@@ -1532,7 +1564,7 @@ int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd)
        dir = nd->dentry;
        nd->flags &= ~LOOKUP_PARENT;
        down(&dir->d_inode->i_sem);
-       path.dentry = __lookup_hash(&nd->last, nd->dentry, nd);
+       path.dentry = lookup_hash(nd);
        path.mnt = nd->mnt;
 
 do_last:
@@ -1634,7 +1666,7 @@ do_link:
        }
        dir = nd->dentry;
        down(&dir->d_inode->i_sem);
-       path.dentry = __lookup_hash(&nd->last, nd->dentry, nd);
+       path.dentry = lookup_hash(nd);
        path.mnt = nd->mnt;
        __putname(nd->last.name);
        goto do_last;
@@ -1666,7 +1698,7 @@ struct dentry *lookup_create(struct nameidata *nd, int is_dir)
        /*
         * Do the final lookup.
         */
-       dentry = lookup_hash(&nd->last, nd->dentry);
+       dentry = lookup_hash(nd);
        if (IS_ERR(dentry))
                goto fail;
 
@@ -1901,7 +1933,7 @@ asmlinkage long sys_rmdir(const char __user * pathname)
                        goto exit1;
        }
        down(&nd.dentry->d_inode->i_sem);
-       dentry = lookup_hash(&nd.last, nd.dentry);
+       dentry = lookup_hash(&nd);
        error = PTR_ERR(dentry);
        if (!IS_ERR(dentry)) {
                error = vfs_rmdir(nd.dentry->d_inode, dentry);
@@ -1970,7 +2002,7 @@ asmlinkage long sys_unlink(const char __user * pathname)
        if (nd.last_type != LAST_NORM)
                goto exit1;
        down(&nd.dentry->d_inode->i_sem);
-       dentry = lookup_hash(&nd.last, nd.dentry);
+       dentry = lookup_hash(&nd);
        error = PTR_ERR(dentry);
        if (!IS_ERR(dentry)) {
                /* Why not before? Because we want correct error value */
@@ -2313,7 +2345,7 @@ static inline int do_rename(const char * oldname, const char * newname)
 
        trap = lock_rename(new_dir, old_dir);
 
-       old_dentry = lookup_hash(&oldnd.last, old_dir);
+       old_dentry = lookup_hash(&oldnd);
        error = PTR_ERR(old_dentry);
        if (IS_ERR(old_dentry))
                goto exit3;
@@ -2333,7 +2365,7 @@ static inline int do_rename(const char * oldname, const char * newname)
        error = -EINVAL;
        if (old_dentry == trap)
                goto exit4;
-       new_dentry = lookup_hash(&newnd.last, new_dir);
+       new_dentry = lookup_hash(&newnd);
        error = PTR_ERR(new_dentry);
        if (IS_ERR(new_dentry))
                goto exit4;
@@ -2536,6 +2568,8 @@ EXPORT_SYMBOL(path_lookup);
 EXPORT_SYMBOL(path_release);
 EXPORT_SYMBOL(path_walk);
 EXPORT_SYMBOL(permission);
+EXPORT_SYMBOL(vfs_permission);
+EXPORT_SYMBOL(file_permission);
 EXPORT_SYMBOL(unlock_rename);
 EXPORT_SYMBOL(vfs_create);
 EXPORT_SYMBOL(vfs_follow_link);