1 files changed, 360 insertions, 0 deletions
diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c
new file mode 100644
index 000000000..a19891015
--- /dev/null
+++ b/fs/9p/vfs_addr.c
@@ -0,0 +1,360 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * 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>
+ */
+
+#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/swap.h>
+#include <linux/uio.h>
+#include <linux/netfs.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_issue_read - Issue a read from 9P
+ * @subreq: The read to make
+ */
+static void v9fs_issue_read(struct netfs_io_subrequest *subreq)
+{
+	struct netfs_io_request *rreq = subreq->rreq;
+	struct p9_fid *fid = rreq->netfs_priv;
+	struct iov_iter to;
+	loff_t pos = subreq->start + subreq->transferred;
+	size_t len = subreq->len   - subreq->transferred;
+	int total, err;
+
+	iov_iter_xarray(&to, ITER_DEST, &rreq->mapping->i_pages, pos, len);
+
+	total = p9_client_read(fid, pos, &to, &err);
+
+	/* if we just extended the file size, any portion not in
+	 * cache won't be on server and is zeroes */
+	__set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);
+
+	netfs_subreq_terminated(subreq, err ?: total, false);
+}
+
+/**
+ * v9fs_init_request - Initialise a read request
+ * @rreq: The read request
+ * @file: The file being read from
+ */
+static int v9fs_init_request(struct netfs_io_request *rreq, struct file *file)
+{
+	struct inode *inode = file_inode(file);
+	struct v9fs_inode *v9inode = V9FS_I(inode);
+	struct p9_fid *fid = file->private_data;
+
+	BUG_ON(!fid);
+
+	/* we might need to read from a fid that was opened write-only
+	 * for read-modify-write of page cache, use the writeback fid
+	 * for that */
+	if (rreq->origin == NETFS_READ_FOR_WRITE &&
+			(fid->mode & O_ACCMODE) == O_WRONLY) {
+		fid = v9inode->writeback_fid;
+		BUG_ON(!fid);
+	}
+
+	p9_fid_get(fid);
+	rreq->netfs_priv = fid;
+	return 0;
+}
+
+/**
+ * v9fs_free_request - Cleanup request initialized by v9fs_init_rreq
+ * @rreq: The I/O request to clean up
+ */
+static void v9fs_free_request(struct netfs_io_request *rreq)
+{
+	struct p9_fid *fid = rreq->netfs_priv;
+
+	p9_fid_put(fid);
+}
+
+/**
+ * v9fs_begin_cache_operation - Begin a cache operation for a read
+ * @rreq: The read request
+ */
+static int v9fs_begin_cache_operation(struct netfs_io_request *rreq)
+{
+#ifdef CONFIG_9P_FSCACHE
+	struct fscache_cookie *cookie = v9fs_inode_cookie(V9FS_I(rreq->inode));
+
+	return fscache_begin_read_operation(&rreq->cache_resources, cookie);
+#else
+	return -ENOBUFS;
+#endif
+}
+
+const struct netfs_request_ops v9fs_req_ops = {
+	.init_request		= v9fs_init_request,
+	.free_request		= v9fs_free_request,
+	.begin_cache_operation	= v9fs_begin_cache_operation,
+	.issue_read		= v9fs_issue_read,
+};
+
+/**
+ * v9fs_release_folio - release the private state associated with a folio
+ * @folio: The folio to be released
+ * @gfp: The caller's allocation restrictions
+ *
+ * Returns true if the page can be released, false otherwise.
+ */
+
+static bool v9fs_release_folio(struct folio *folio, gfp_t gfp)
+{
+	struct inode *inode = folio_inode(folio);
+
+	if (folio_test_private(folio))
+		return false;
+#ifdef CONFIG_9P_FSCACHE
+	if (folio_test_fscache(folio)) {
+		if (current_is_kswapd() || !(gfp & __GFP_FS))
+			return false;
+		folio_wait_fscache(folio);
+	}
+#endif
+	fscache_note_page_release(v9fs_inode_cookie(V9FS_I(inode)));
+	return true;
+}
+
+static void v9fs_invalidate_folio(struct folio *folio, size_t offset,
+				 size_t length)
+{
+	folio_wait_fscache(folio);
+}
+
+static void v9fs_write_to_cache_done(void *priv, ssize_t transferred_or_error,
+				     bool was_async)
+{
+	struct v9fs_inode *v9inode = priv;
+	__le32 version;
+
+	if (IS_ERR_VALUE(transferred_or_error) &&
+	    transferred_or_error != -ENOBUFS) {
+		version = cpu_to_le32(v9inode->qid.version);
+		fscache_invalidate(v9fs_inode_cookie(v9inode), &version,
+				   i_size_read(&v9inode->netfs.inode), 0);
+	}
+}
+
+static int v9fs_vfs_write_folio_locked(struct folio *folio)
+{
+	struct inode *inode = folio_inode(folio);
+	struct v9fs_inode *v9inode = V9FS_I(inode);
+	struct fscache_cookie *cookie = v9fs_inode_cookie(v9inode);
+	loff_t start = folio_pos(folio);
+	loff_t i_size = i_size_read(inode);
+	struct iov_iter from;
+	size_t len = folio_size(folio);
+	int err;
+
+	if (start >= i_size)
+		return 0; /* Simultaneous truncation occurred */
+
+	len = min_t(loff_t, i_size - start, len);
+
+	iov_iter_xarray(&from, ITER_SOURCE, &folio_mapping(folio)->i_pages, start, len);
+
+	/* We should have writeback_fid always set */
+	BUG_ON(!v9inode->writeback_fid);
+
+	folio_wait_fscache(folio);
+	folio_start_writeback(folio);
+
+	p9_client_write(v9inode->writeback_fid, start, &from, &err);
+
+	if (err == 0 &&
+	    fscache_cookie_enabled(cookie) &&
+	    test_bit(FSCACHE_COOKIE_IS_CACHING, &cookie->flags)) {
+		folio_start_fscache(folio);
+		fscache_write_to_cache(v9fs_inode_cookie(v9inode),
+				       folio_mapping(folio), start, len, i_size,
+				       v9fs_write_to_cache_done, v9inode,
+				       true);
+	}
+
+	folio_end_writeback(folio);
+	return err;
+}
+
+static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc)
+{
+	struct folio *folio = page_folio(page);
+	int retval;
+
+	p9_debug(P9_DEBUG_VFS, "folio %p\n", folio);
+
+	retval = v9fs_vfs_write_folio_locked(folio);
+	if (retval < 0) {
+		if (retval == -EAGAIN) {
+			folio_redirty_for_writepage(wbc, folio);
+			retval = 0;
+		} else {
+			mapping_set_error(folio_mapping(folio), retval);
+		}
+	} else
+		retval = 0;
+
+	folio_unlock(folio);
+	return retval;
+}
+
+static int v9fs_launder_folio(struct folio *folio)
+{
+	int retval;
+
+	if (folio_clear_dirty_for_io(folio)) {
+		retval = v9fs_vfs_write_folio_locked(folio);
+		if (retval)
+			return retval;
+	}
+	folio_wait_fscache(folio);
+	return 0;
+}
+
+/**
+ * v9fs_direct_IO - 9P address space operation for direct I/O
+ * @iocb: target I/O control block
+ * @iter: The data/buffer to use
+ *
+ * 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 int len,
+			    struct page **subpagep, void **fsdata)
+{
+	int retval;
+	struct folio *folio;
+	struct v9fs_inode *v9inode = V9FS_I(mapping->host);
+
+	p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);
+
+	BUG_ON(!v9inode->writeback_fid);
+
+	/* Prefetch area to be written into the cache if we're caching this
+	 * file.  We need to do this before we get a lock on the page in case
+	 * there's more than one writer competing for the same cache block.
+	 */
+	retval = netfs_write_begin(&v9inode->netfs, filp, mapping, pos, len, &folio, fsdata);
+	if (retval < 0)
+		return retval;
+
+	*subpagep = &folio->page;
+	return retval;
+}
+
+static int v9fs_write_end(struct file *filp, struct address_space *mapping,
+			  loff_t pos, unsigned int len, unsigned int copied,
+			  struct page *subpage, void *fsdata)
+{
+	loff_t last_pos = pos + copied;
+	struct folio *folio = page_folio(subpage);
+	struct inode *inode = mapping->host;
+	struct v9fs_inode *v9inode = V9FS_I(inode);
+
+	p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping);
+
+	if (!folio_test_uptodate(folio)) {
+		if (unlikely(copied < len)) {
+			copied = 0;
+			goto out;
+		}
+
+		folio_mark_uptodate(folio);
+	}
+
+	/*
+	 * 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);
+		fscache_update_cookie(v9fs_inode_cookie(v9inode), NULL, &last_pos);
+	}
+	folio_mark_dirty(folio);
+out:
+	folio_unlock(folio);
+	folio_put(folio);
+
+	return copied;
+}
+
+#ifdef CONFIG_9P_FSCACHE
+/*
+ * Mark a page as having been made dirty and thus needing writeback.  We also
+ * need to pin the cache object to write back to.
+ */
+static bool v9fs_dirty_folio(struct address_space *mapping, struct folio *folio)
+{
+	struct v9fs_inode *v9inode = V9FS_I(mapping->host);
+
+	return fscache_dirty_folio(mapping, folio, v9fs_inode_cookie(v9inode));
+}
+#else
+#define v9fs_dirty_folio filemap_dirty_folio
+#endif
+
+const struct address_space_operations v9fs_addr_operations = {
+	.read_folio = netfs_read_folio,
+	.readahead = netfs_readahead,
+	.dirty_folio = v9fs_dirty_folio,
+	.writepage = v9fs_vfs_writepage,
+	.write_begin = v9fs_write_begin,
+	.write_end = v9fs_write_end,
+	.release_folio = v9fs_release_folio,
+	.invalidate_folio = v9fs_invalidate_folio,
+	.launder_folio = v9fs_launder_folio,
+	.direct_IO = v9fs_direct_IO,
+};