v4.19.13 snapshot.
diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c
new file mode 100644
index 0000000..e1cbdfd
--- /dev/null
+++ b/fs/9p/vfs_addr.c
@@ -0,0 +1,349 @@
+/*
+ * 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 <linux/bvec.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_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_SHIFT)
+ len = size & ~PAGE_MASK;
+ else
+ len = PAGE_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
+ *
+ * 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)
+{
+ struct file *file = iocb->ki_filp;
+ loff_t pos = iocb->ki_pos;
+ 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_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_SIZE)
+ goto out;
+
+ retval = v9fs_fid_readpage(v9inode->writeback_fid, page);
+ put_page(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 (!PageUptodate(page)) {
+ if (unlikely(copied < len)) {
+ copied = 0;
+ goto out;
+ } else if (len == PAGE_SIZE) {
+ 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);
+out:
+ unlock_page(page);
+ put_page(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,
+};