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- /*
- * linux/fs/9p/vfs_addr.c
- *
- * This file contians vfs address (mmap) ops for 9P2000.
- *
- * Copyright (C) 2005 by Eric Van Hensbergen <ericvh@gmail.com>
- * Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2
- * as published by the Free Software Foundation.
- *
- * 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:
- * Free Software Foundation
- * 51 Franklin Street, Fifth Floor
- * Boston, MA 02111-1301 USA
- *
- */
- #include <linux/module.h>
- #include <linux/errno.h>
- #include <linux/fs.h>
- #include <linux/file.h>
- #include <linux/stat.h>
- #include <linux/string.h>
- #include <linux/inet.h>
- #include <linux/pagemap.h>
- #include <linux/idr.h>
- #include <linux/sched.h>
- #include <linux/uio.h>
- #include <net/9p/9p.h>
- #include <net/9p/client.h>
- #include "v9fs.h"
- #include "v9fs_vfs.h"
- #include "cache.h"
- #include "fid.h"
- /**
- * v9fs_fid_readpage - read an entire page in from 9P
- *
- * @fid: fid being read
- * @page: structure to page
- *
- */
- static int v9fs_fid_readpage(struct p9_fid *fid, struct page *page)
- {
- struct inode *inode = page->mapping->host;
- struct bio_vec bvec = {.bv_page = page, .bv_len = PAGE_SIZE};
- struct iov_iter to;
- int retval, err;
- p9_debug(P9_DEBUG_VFS, "\n");
- BUG_ON(!PageLocked(page));
- retval = v9fs_readpage_from_fscache(inode, page);
- if (retval == 0)
- return retval;
- iov_iter_bvec(&to, ITER_BVEC | READ, &bvec, 1, PAGE_SIZE);
- retval = p9_client_read(fid, page_offset(page), &to, &err);
- if (err) {
- v9fs_uncache_page(inode, page);
- retval = err;
- goto done;
- }
- zero_user(page, retval, PAGE_SIZE - retval);
- flush_dcache_page(page);
- SetPageUptodate(page);
- v9fs_readpage_to_fscache(inode, page);
- retval = 0;
- done:
- unlock_page(page);
- return retval;
- }
- /**
- * v9fs_vfs_readpage - read an entire page in from 9P
- *
- * @filp: file being read
- * @page: structure to page
- *
- */
- static int v9fs_vfs_readpage(struct file *filp, struct page *page)
- {
- return v9fs_fid_readpage(filp->private_data, page);
- }
- /**
- * v9fs_vfs_readpages - read a set of pages from 9P
- *
- * @filp: file being read
- * @mapping: the address space
- * @pages: list of pages to read
- * @nr_pages: count of pages to read
- *
- */
- static int v9fs_vfs_readpages(struct file *filp, struct address_space *mapping,
- struct list_head *pages, unsigned nr_pages)
- {
- int ret = 0;
- struct inode *inode;
- inode = mapping->host;
- p9_debug(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, filp);
- ret = v9fs_readpages_from_fscache(inode, mapping, pages, &nr_pages);
- if (ret == 0)
- return ret;
- ret = read_cache_pages(mapping, pages, (void *)v9fs_vfs_readpage, filp);
- p9_debug(P9_DEBUG_VFS, " = %d\n", ret);
- return ret;
- }
- /**
- * v9fs_release_page - release the private state associated with a page
- *
- * Returns 1 if the page can be released, false otherwise.
- */
- static int v9fs_release_page(struct page *page, gfp_t gfp)
- {
- if (PagePrivate(page))
- return 0;
- return v9fs_fscache_release_page(page, gfp);
- }
- /**
- * v9fs_invalidate_page - Invalidate a page completely or partially
- *
- * @page: structure to page
- * @offset: offset in the page
- */
- static void v9fs_invalidate_page(struct page *page, unsigned int offset,
- unsigned int length)
- {
- /*
- * If called with zero offset, we should release
- * the private state assocated with the page
- */
- if (offset == 0 && length == PAGE_CACHE_SIZE)
- v9fs_fscache_invalidate_page(page);
- }
- static int v9fs_vfs_writepage_locked(struct page *page)
- {
- struct inode *inode = page->mapping->host;
- struct v9fs_inode *v9inode = V9FS_I(inode);
- loff_t size = i_size_read(inode);
- struct iov_iter from;
- struct bio_vec bvec;
- int err, len;
- if (page->index == size >> PAGE_CACHE_SHIFT)
- len = size & ~PAGE_CACHE_MASK;
- else
- len = PAGE_CACHE_SIZE;
- bvec.bv_page = page;
- bvec.bv_offset = 0;
- bvec.bv_len = len;
- iov_iter_bvec(&from, ITER_BVEC | WRITE, &bvec, 1, len);
- /* We should have writeback_fid always set */
- BUG_ON(!v9inode->writeback_fid);
- set_page_writeback(page);
- p9_client_write(v9inode->writeback_fid, page_offset(page), &from, &err);
- end_page_writeback(page);
- return err;
- }
- static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc)
- {
- int retval;
- p9_debug(P9_DEBUG_VFS, "page %p\n", page);
- retval = v9fs_vfs_writepage_locked(page);
- if (retval < 0) {
- if (retval == -EAGAIN) {
- redirty_page_for_writepage(wbc, page);
- retval = 0;
- } else {
- SetPageError(page);
- mapping_set_error(page->mapping, retval);
- }
- } else
- retval = 0;
- unlock_page(page);
- return retval;
- }
- /**
- * v9fs_launder_page - Writeback a dirty page
- * Returns 0 on success.
- */
- static int v9fs_launder_page(struct page *page)
- {
- int retval;
- struct inode *inode = page->mapping->host;
- v9fs_fscache_wait_on_page_write(inode, page);
- if (clear_page_dirty_for_io(page)) {
- retval = v9fs_vfs_writepage_locked(page);
- if (retval)
- return retval;
- }
- return 0;
- }
- /**
- * v9fs_direct_IO - 9P address space operation for direct I/O
- * @iocb: target I/O control block
- * @pos: offset in file to begin the operation
- *
- * The presence of v9fs_direct_IO() in the address space ops vector
- * allowes open() O_DIRECT flags which would have failed otherwise.
- *
- * In the non-cached mode, we shunt off direct read and write requests before
- * the VFS gets them, so this method should never be called.
- *
- * Direct IO is not 'yet' supported in the cached mode. Hence when
- * this routine is called through generic_file_aio_read(), the read/write fails
- * with an error.
- *
- */
- static ssize_t
- v9fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t pos)
- {
- struct file *file = iocb->ki_filp;
- ssize_t n;
- int err = 0;
- if (iov_iter_rw(iter) == WRITE) {
- n = p9_client_write(file->private_data, pos, iter, &err);
- if (n) {
- struct inode *inode = file_inode(file);
- loff_t i_size = i_size_read(inode);
- if (pos + n > i_size)
- inode_add_bytes(inode, pos + n - i_size);
- }
- } else {
- n = p9_client_read(file->private_data, pos, iter, &err);
- }
- return n ? n : err;
- }
- static int v9fs_write_begin(struct file *filp, struct address_space *mapping,
- loff_t pos, unsigned len, unsigned flags,
- struct page **pagep, void **fsdata)
- {
- int retval = 0;
- struct page *page;
- struct v9fs_inode *v9inode;
- pgoff_t index = pos >> PAGE_CACHE_SHIFT;
- struct inode *inode = mapping->host;
- p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);
- v9inode = V9FS_I(inode);
- start:
- page = grab_cache_page_write_begin(mapping, index, flags);
- if (!page) {
- retval = -ENOMEM;
- goto out;
- }
- BUG_ON(!v9inode->writeback_fid);
- if (PageUptodate(page))
- goto out;
- if (len == PAGE_CACHE_SIZE)
- goto out;
- retval = v9fs_fid_readpage(v9inode->writeback_fid, page);
- page_cache_release(page);
- if (!retval)
- goto start;
- out:
- *pagep = page;
- return retval;
- }
- static int v9fs_write_end(struct file *filp, struct address_space *mapping,
- loff_t pos, unsigned len, unsigned copied,
- struct page *page, void *fsdata)
- {
- loff_t last_pos = pos + copied;
- struct inode *inode = page->mapping->host;
- p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);
- if (unlikely(copied < len)) {
- /*
- * zero out the rest of the area
- */
- unsigned from = pos & (PAGE_CACHE_SIZE - 1);
- zero_user(page, from + copied, len - copied);
- flush_dcache_page(page);
- }
- if (!PageUptodate(page))
- SetPageUptodate(page);
- /*
- * No need to use i_size_read() here, the i_size
- * cannot change under us because we hold the i_mutex.
- */
- if (last_pos > inode->i_size) {
- inode_add_bytes(inode, last_pos - inode->i_size);
- i_size_write(inode, last_pos);
- }
- set_page_dirty(page);
- unlock_page(page);
- page_cache_release(page);
- return copied;
- }
- const struct address_space_operations v9fs_addr_operations = {
- .readpage = v9fs_vfs_readpage,
- .readpages = v9fs_vfs_readpages,
- .set_page_dirty = __set_page_dirty_nobuffers,
- .writepage = v9fs_vfs_writepage,
- .write_begin = v9fs_write_begin,
- .write_end = v9fs_write_end,
- .releasepage = v9fs_release_page,
- .invalidatepage = v9fs_invalidate_page,
- .launder_page = v9fs_launder_page,
- .direct_IO = v9fs_direct_IO,
- };
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