linux/fs/9p/vfs_addr.c
Eric Van Hensbergen 344504e912
fs/9p: Expand setup of writeback cache to all levels
If cache is enabled, make sure we are putting the right things
in place (mainly impacts mmap).  This also sets us up for more
cache levels.

Signed-off-by: Eric Van Hensbergen <ericvh@kernel.org>
Reviewed-by: Dominique Martinet <asmadeus@codewreck.org>
2023-02-23 22:39:36 +00:00

358 lines
9.2 KiB
C

// 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/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);
/* 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,
};