1 files changed, 360 insertions, 0 deletions

diff --git a/fs/configfs/file.c b/fs/configfs/file.c
new file mode 100644
index 000000000000..af1ffc9a15c0
--- /dev/null
+++ b/fs/configfs/file.c
@@ -0,0 +1,360 @@
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * file.c - operations for regular (text) files.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ *
+ * Based on sysfs:
+ *      sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
+ *
+ * configfs Copyright (C) 2005 Oracle.  All rights reserved.
+ */
+
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/dnotify.h>
+#include <linux/slab.h>
+#include <asm/uaccess.h>
+#include <asm/semaphore.h>
+
+#include <linux/configfs.h>
+#include "configfs_internal.h"
+
+
+struct configfs_buffer {
+        size_t                  count;
+        loff_t                  pos;
+        char                    * page;
+        struct configfs_item_operations * ops;
+        struct semaphore        sem;
+        int                     needs_read_fill;
+};
+
+
+/**
+ *      fill_read_buffer - allocate and fill buffer from item.
+ *      @dentry:        dentry pointer.
+ *      @buffer:        data buffer for file.
+ *
+ *      Allocate @buffer->page, if it hasn't been already, then call the
+ *      config_item's show() method to fill the buffer with this attribute's
+ *      data.
+ *      This is called only once, on the file's first read.
+ */
+static int fill_read_buffer(struct dentry * dentry, struct configfs_buffer * buffer)
+{
+        struct configfs_attribute * attr = to_attr(dentry);
+        struct config_item * item = to_item(dentry->d_parent);
+        struct configfs_item_operations * ops = buffer->ops;
+        int ret = 0;
+        ssize_t count;
+
+        if (!buffer->page)
+                buffer->page = (char *) get_zeroed_page(GFP_KERNEL);
+        if (!buffer->page)
+                return -ENOMEM;
+
+        count = ops->show_attribute(item,attr,buffer->page);
+        buffer->needs_read_fill = 0;
+        BUG_ON(count > (ssize_t)PAGE_SIZE);
+        if (count >= 0)
+                buffer->count = count;
+        else
+                ret = count;
+        return ret;
+}
+
+
+/**
+ *      flush_read_buffer - push buffer to userspace.
+ *      @buffer:        data buffer for file.
+ *      @userbuf:       user-passed buffer.
+ *      @count:         number of bytes requested.
+ *      @ppos:          file position.
+ *
+ *      Copy the buffer we filled in fill_read_buffer() to userspace.
+ *      This is done at the reader's leisure, copying and advancing
+ *      the amount they specify each time.
+ *      This may be called continuously until the buffer is empty.
+ */
+static int flush_read_buffer(struct configfs_buffer * buffer, char __user * buf,
+                             size_t count, loff_t * ppos)
+{
+        int error;
+
+        if (*ppos > buffer->count)
+                return 0;
+
+        if (count > (buffer->count - *ppos))
+                count = buffer->count - *ppos;
+
+        error = copy_to_user(buf,buffer->page + *ppos,count);
+        if (!error)
+                *ppos += count;
+        return error ? -EFAULT : count;
+}
+
+/**
+ *      configfs_read_file - read an attribute.
+ *      @file:  file pointer.
+ *      @buf:   buffer to fill.
+ *      @count: number of bytes to read.
+ *      @ppos:  starting offset in file.
+ *
+ *      Userspace wants to read an attribute file. The attribute descriptor
+ *      is in the file's ->d_fsdata. The target item is in the directory's
+ *      ->d_fsdata.
+ *
+ *      We call fill_read_buffer() to allocate and fill the buffer from the
+ *      item's show() method exactly once (if the read is happening from
+ *      the beginning of the file). That should fill the entire buffer with
+ *      all the data the item has to offer for that attribute.
+ *      We then call flush_read_buffer() to copy the buffer to userspace
+ *      in the increments specified.
+ */
+
+static ssize_t
+configfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos)
+{
+        struct configfs_buffer * buffer = file->private_data;
+        ssize_t retval = 0;
+
+        down(&buffer->sem);
+        if (buffer->needs_read_fill) {
+                if ((retval = fill_read_buffer(file->f_dentry,buffer)))
+                        goto out;
+        }
+        pr_debug("%s: count = %d, ppos = %lld, buf = %s\n",
+                 __FUNCTION__,count,*ppos,buffer->page);
+        retval = flush_read_buffer(buffer,buf,count,ppos);
+out:
+        up(&buffer->sem);
+        return retval;
+}
+
+
+/**
+ *      fill_write_buffer - copy buffer from userspace.
+ *      @buffer:        data buffer for file.
+ *      @userbuf:       data from user.
+ *      @count:         number of bytes in @userbuf.
+ *
+ *      Allocate @buffer->page if it hasn't been already, then
+ *      copy the user-supplied buffer into it.
+ */
+
+static int
+fill_write_buffer(struct configfs_buffer * buffer, const char __user * buf, size_t count)
+{
+        int error;
+
+        if (!buffer->page)
+                buffer->page = (char *)get_zeroed_page(GFP_KERNEL);
+        if (!buffer->page)
+                return -ENOMEM;
+
+        if (count > PAGE_SIZE)
+                count = PAGE_SIZE;
+        error = copy_from_user(buffer->page,buf,count);
+        buffer->needs_read_fill = 1;
+        return error ? -EFAULT : count;
+}
+
+
+/**
+ *      flush_write_buffer - push buffer to config_item.
+ *      @file:          file pointer.
+ *      @buffer:        data buffer for file.
+ *
+ *      Get the correct pointers for the config_item and the attribute we're
+ *      dealing with, then call the store() method for the attribute,
+ *      passing the buffer that we acquired in fill_write_buffer().
+ */
+
+static int
+flush_write_buffer(struct dentry * dentry, struct configfs_buffer * buffer, size_t count)
+{
+        struct configfs_attribute * attr = to_attr(dentry);
+        struct config_item * item = to_item(dentry->d_parent);
+        struct configfs_item_operations * ops = buffer->ops;
+
+        return ops->store_attribute(item,attr,buffer->page,count);
+}
+
+
+/**
+ *      configfs_write_file - write an attribute.
+ *      @file:  file pointer
+ *      @buf:   data to write
+ *      @count: number of bytes
+ *      @ppos:  starting offset
+ *
+ *      Similar to configfs_read_file(), though working in the opposite direction.
+ *      We allocate and fill the data from the user in fill_write_buffer(),
+ *      then push it to the config_item in flush_write_buffer().
+ *      There is no easy way for us to know if userspace is only doing a partial
+ *      write, so we don't support them. We expect the entire buffer to come
+ *      on the first write.
+ *      Hint: if you're writing a value, first read the file, modify only the
+ *      the value you're changing, then write entire buffer back.
+ */
+
+static ssize_t
+configfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
+{
+        struct configfs_buffer * buffer = file->private_data;
+
+        down(&buffer->sem);
+        count = fill_write_buffer(buffer,buf,count);
+        if (count > 0)
+                count = flush_write_buffer(file->f_dentry,buffer,count);
+        if (count > 0)
+                *ppos += count;
+        up(&buffer->sem);
+        return count;
+}
+
+static int check_perm(struct inode * inode, struct file * file)
+{
+        struct config_item *item = configfs_get_config_item(file->f_dentry->d_parent);
+        struct configfs_attribute * attr = to_attr(file->f_dentry);
+        struct configfs_buffer * buffer;
+        struct configfs_item_operations * ops = NULL;
+        int error = 0;
+
+        if (!item || !attr)
+                goto Einval;
+
+        /* Grab the module reference for this attribute if we have one */
+        if (!try_module_get(attr->ca_owner)) {
+                error = -ENODEV;
+                goto Done;
+        }
+
+        if (item->ci_type)
+                ops = item->ci_type->ct_item_ops;
+        else
+                goto Eaccess;
+
+        /* File needs write support.
+         * The inode's perms must say it's ok,
+         * and we must have a store method.
+         */
+        if (file->f_mode & FMODE_WRITE) {
+
+                if (!(inode->i_mode & S_IWUGO) || !ops->store_attribute)
+                        goto Eaccess;
+
+        }
+
+        /* File needs read support.
+         * The inode's perms must say it's ok, and we there
+         * must be a show method for it.
+         */
+        if (file->f_mode & FMODE_READ) {
+                if (!(inode->i_mode & S_IRUGO) || !ops->show_attribute)
+                        goto Eaccess;
+        }
+
+        /* No error? Great, allocate a buffer for the file, and store it
+         * it in file->private_data for easy access.
+         */
+        buffer = kmalloc(sizeof(struct configfs_buffer),GFP_KERNEL);
+        if (buffer) {
+                memset(buffer,0,sizeof(struct configfs_buffer));
+                init_MUTEX(&buffer->sem);
+                buffer->needs_read_fill = 1;
+                buffer->ops = ops;
+                file->private_data = buffer;
+        } else
+                error = -ENOMEM;
+        goto Done;
+
+ Einval:
+        error = -EINVAL;
+        goto Done;
+ Eaccess:
+        error = -EACCES;
+        module_put(attr->ca_owner);
+ Done:
+        if (error && item)
+                config_item_put(item);
+        return error;
+}
+
+static int configfs_open_file(struct inode * inode, struct file * filp)
+{
+        return check_perm(inode,filp);
+}
+
+static int configfs_release(struct inode * inode, struct file * filp)
+{
+        struct config_item * item = to_item(filp->f_dentry->d_parent);
+        struct configfs_attribute * attr = to_attr(filp->f_dentry);
+        struct module * owner = attr->ca_owner;
+        struct configfs_buffer * buffer = filp->private_data;
+
+        if (item)
+                config_item_put(item);
+        /* After this point, attr should not be accessed. */
+        module_put(owner);
+
+        if (buffer) {
+                if (buffer->page)
+                        free_page((unsigned long)buffer->page);
+                kfree(buffer);
+        }
+        return 0;
+}
+
+struct file_operations configfs_file_operations = {
+        .read           = configfs_read_file,
+        .write          = configfs_write_file,
+        .llseek         = generic_file_llseek,
+        .open           = configfs_open_file,
+        .release        = configfs_release,
+};
+
+
+int configfs_add_file(struct dentry * dir, const struct configfs_attribute * attr, int type)
+{
+        struct configfs_dirent * parent_sd = dir->d_fsdata;
+        umode_t mode = (attr->ca_mode & S_IALLUGO) | S_IFREG;
+        int error = 0;
+
+        down(&dir->d_inode->i_sem);
+        error = configfs_make_dirent(parent_sd, NULL, (void *) attr, mode, type);
+        up(&dir->d_inode->i_sem);
+
+        return error;
+}
+
+
+/**
+ *      configfs_create_file - create an attribute file for an item.
+ *      @item:  item we're creating for.
+ *      @attr:  atrribute descriptor.
+ */
+
+int configfs_create_file(struct config_item * item, const struct configfs_attribute * attr)
+{
+        BUG_ON(!item || !item->ci_dentry || !attr);
+
+        return configfs_add_file(item->ci_dentry, attr,
+                                 CONFIGFS_ITEM_ATTR);
+}
+