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-rw-r--r--fs/9p/vfs_addr.c360
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,
+};