linux/fs/9p/vfs_super.c
David Howells 93c846143d 9p: Copy local writes to the cache when writing to the server
When writing to the server from v9fs_vfs_writepage(), copy the data to the
cache object too.

To make this possible, the cookie must have its active users count
incremented when the page is dirtied and kept incremented until we manage
to clean up all the pages.  This allows the writeback to take place after
the last file struct is released.

This is done by taking a use on the cookie in v9fs_set_page_dirty() if we
haven't already done so (controlled by the I_PINNING_FSCACHE_WB flag) and
dropping the pin in v9fs_write_inode() if __writeback_single_inode() clears
all the outstanding dirty pages (conveyed by the unpinned_fscache_wb flag
in the writeback_control struct).

Inode eviction must also clear the flag after truncating away all the
outstanding pages.

In the future this will be handled more gracefully by netfslib.

Changes
=======
ver #3:
 - Canonicalise the coherency data to make it endianness-independent.

ver #2:
 - Fix an unused-var warning due to CONFIG_9P_FSCACHE=n[1].

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Jeff Layton <jlayton@kernel.org>
Tested-by: Dominique Martinet <asmadeus@codewreck.org>
cc: Eric Van Hensbergen <ericvh@gmail.com>
cc: Latchesar Ionkov <lucho@ionkov.net>
cc: v9fs-developer@lists.sourceforge.net
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/163819667027.215744.13815687931204222995.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906978015.143852.10646669694345706328.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967180760.1823006.5831751873616248910.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021574522.640689.13849966660182529125.stgit@warthog.procyon.org.uk/ # v4
2022-01-10 11:53:25 +00:00

370 lines
8.1 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
*
* Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
* Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
*/
#include <linux/kernel.h>
#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/mount.h>
#include <linux/idr.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/statfs.h>
#include <linux/magic.h>
#include <linux/fscache.h>
#include <net/9p/9p.h>
#include <net/9p/client.h>
#include "v9fs.h"
#include "v9fs_vfs.h"
#include "fid.h"
#include "xattr.h"
#include "acl.h"
static const struct super_operations v9fs_super_ops, v9fs_super_ops_dotl;
/**
* v9fs_set_super - set the superblock
* @s: super block
* @data: file system specific data
*
*/
static int v9fs_set_super(struct super_block *s, void *data)
{
s->s_fs_info = data;
return set_anon_super(s, data);
}
/**
* v9fs_fill_super - populate superblock with info
* @sb: superblock
* @v9ses: session information
* @flags: flags propagated from v9fs_mount()
*
*/
static int
v9fs_fill_super(struct super_block *sb, struct v9fs_session_info *v9ses,
int flags)
{
int ret;
sb->s_maxbytes = MAX_LFS_FILESIZE;
sb->s_blocksize_bits = fls(v9ses->maxdata - 1);
sb->s_blocksize = 1 << sb->s_blocksize_bits;
sb->s_magic = V9FS_MAGIC;
if (v9fs_proto_dotl(v9ses)) {
sb->s_op = &v9fs_super_ops_dotl;
sb->s_xattr = v9fs_xattr_handlers;
} else {
sb->s_op = &v9fs_super_ops;
sb->s_time_max = U32_MAX;
}
sb->s_time_min = 0;
ret = super_setup_bdi(sb);
if (ret)
return ret;
if (!v9ses->cache) {
sb->s_bdi->ra_pages = 0;
sb->s_bdi->io_pages = 0;
} else {
sb->s_bdi->ra_pages = v9ses->maxdata >> PAGE_SHIFT;
sb->s_bdi->io_pages = v9ses->maxdata >> PAGE_SHIFT;
}
sb->s_flags |= SB_ACTIVE | SB_DIRSYNC;
if (!v9ses->cache)
sb->s_flags |= SB_SYNCHRONOUS;
#ifdef CONFIG_9P_FS_POSIX_ACL
if ((v9ses->flags & V9FS_ACL_MASK) == V9FS_POSIX_ACL)
sb->s_flags |= SB_POSIXACL;
#endif
return 0;
}
/**
* v9fs_mount - mount a superblock
* @fs_type: file system type
* @flags: mount flags
* @dev_name: device name that was mounted
* @data: mount options
*
*/
static struct dentry *v9fs_mount(struct file_system_type *fs_type, int flags,
const char *dev_name, void *data)
{
struct super_block *sb = NULL;
struct inode *inode = NULL;
struct dentry *root = NULL;
struct v9fs_session_info *v9ses = NULL;
umode_t mode = 0777 | S_ISVTX;
struct p9_fid *fid;
int retval = 0;
p9_debug(P9_DEBUG_VFS, "\n");
v9ses = kzalloc(sizeof(struct v9fs_session_info), GFP_KERNEL);
if (!v9ses)
return ERR_PTR(-ENOMEM);
fid = v9fs_session_init(v9ses, dev_name, data);
if (IS_ERR(fid)) {
retval = PTR_ERR(fid);
goto free_session;
}
sb = sget(fs_type, NULL, v9fs_set_super, flags, v9ses);
if (IS_ERR(sb)) {
retval = PTR_ERR(sb);
goto clunk_fid;
}
retval = v9fs_fill_super(sb, v9ses, flags);
if (retval)
goto release_sb;
if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
sb->s_d_op = &v9fs_cached_dentry_operations;
else
sb->s_d_op = &v9fs_dentry_operations;
inode = v9fs_get_inode(sb, S_IFDIR | mode, 0);
if (IS_ERR(inode)) {
retval = PTR_ERR(inode);
goto release_sb;
}
root = d_make_root(inode);
if (!root) {
retval = -ENOMEM;
goto release_sb;
}
sb->s_root = root;
if (v9fs_proto_dotl(v9ses)) {
struct p9_stat_dotl *st = NULL;
st = p9_client_getattr_dotl(fid, P9_STATS_BASIC);
if (IS_ERR(st)) {
retval = PTR_ERR(st);
goto release_sb;
}
d_inode(root)->i_ino = v9fs_qid2ino(&st->qid);
v9fs_stat2inode_dotl(st, d_inode(root), 0);
kfree(st);
} else {
struct p9_wstat *st = NULL;
st = p9_client_stat(fid);
if (IS_ERR(st)) {
retval = PTR_ERR(st);
goto release_sb;
}
d_inode(root)->i_ino = v9fs_qid2ino(&st->qid);
v9fs_stat2inode(st, d_inode(root), sb, 0);
p9stat_free(st);
kfree(st);
}
retval = v9fs_get_acl(inode, fid);
if (retval)
goto release_sb;
v9fs_fid_add(root, fid);
p9_debug(P9_DEBUG_VFS, " simple set mount, return 0\n");
return dget(sb->s_root);
clunk_fid:
p9_client_clunk(fid);
v9fs_session_close(v9ses);
free_session:
kfree(v9ses);
return ERR_PTR(retval);
release_sb:
/*
* we will do the session_close and root dentry release
* in the below call. But we need to clunk fid, because we haven't
* attached the fid to dentry so it won't get clunked
* automatically.
*/
p9_client_clunk(fid);
deactivate_locked_super(sb);
return ERR_PTR(retval);
}
/**
* v9fs_kill_super - Kill Superblock
* @s: superblock
*
*/
static void v9fs_kill_super(struct super_block *s)
{
struct v9fs_session_info *v9ses = s->s_fs_info;
p9_debug(P9_DEBUG_VFS, " %p\n", s);
kill_anon_super(s);
v9fs_session_cancel(v9ses);
v9fs_session_close(v9ses);
kfree(v9ses);
s->s_fs_info = NULL;
p9_debug(P9_DEBUG_VFS, "exiting kill_super\n");
}
static void
v9fs_umount_begin(struct super_block *sb)
{
struct v9fs_session_info *v9ses;
v9ses = sb->s_fs_info;
v9fs_session_begin_cancel(v9ses);
}
static int v9fs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
struct v9fs_session_info *v9ses;
struct p9_fid *fid;
struct p9_rstatfs rs;
int res;
fid = v9fs_fid_lookup(dentry);
if (IS_ERR(fid)) {
res = PTR_ERR(fid);
goto done;
}
v9ses = v9fs_dentry2v9ses(dentry);
if (v9fs_proto_dotl(v9ses)) {
res = p9_client_statfs(fid, &rs);
if (res == 0) {
buf->f_type = rs.type;
buf->f_bsize = rs.bsize;
buf->f_blocks = rs.blocks;
buf->f_bfree = rs.bfree;
buf->f_bavail = rs.bavail;
buf->f_files = rs.files;
buf->f_ffree = rs.ffree;
buf->f_fsid = u64_to_fsid(rs.fsid);
buf->f_namelen = rs.namelen;
}
if (res != -ENOSYS)
goto done;
}
res = simple_statfs(dentry, buf);
done:
p9_client_clunk(fid);
return res;
}
static int v9fs_drop_inode(struct inode *inode)
{
struct v9fs_session_info *v9ses;
v9ses = v9fs_inode2v9ses(inode);
if (v9ses->cache == CACHE_LOOSE || v9ses->cache == CACHE_FSCACHE)
return generic_drop_inode(inode);
/*
* in case of non cached mode always drop the
* inode because we want the inode attribute
* to always match that on the server.
*/
return 1;
}
static int v9fs_write_inode(struct inode *inode,
struct writeback_control *wbc)
{
int ret;
struct p9_wstat wstat;
struct v9fs_inode *v9inode;
/*
* send an fsync request to server irrespective of
* wbc->sync_mode.
*/
p9_debug(P9_DEBUG_VFS, "%s: inode %p\n", __func__, inode);
v9inode = V9FS_I(inode);
if (!v9inode->writeback_fid)
return 0;
v9fs_blank_wstat(&wstat);
ret = p9_client_wstat(v9inode->writeback_fid, &wstat);
if (ret < 0) {
__mark_inode_dirty(inode, I_DIRTY_DATASYNC);
return ret;
}
fscache_unpin_writeback(wbc, v9fs_inode_cookie(v9inode));
return 0;
}
static int v9fs_write_inode_dotl(struct inode *inode,
struct writeback_control *wbc)
{
int ret;
struct v9fs_inode *v9inode;
/*
* send an fsync request to server irrespective of
* wbc->sync_mode.
*/
v9inode = V9FS_I(inode);
p9_debug(P9_DEBUG_VFS, "%s: inode %p, writeback_fid %p\n",
__func__, inode, v9inode->writeback_fid);
if (!v9inode->writeback_fid)
return 0;
ret = p9_client_fsync(v9inode->writeback_fid, 0);
if (ret < 0) {
__mark_inode_dirty(inode, I_DIRTY_DATASYNC);
return ret;
}
fscache_unpin_writeback(wbc, v9fs_inode_cookie(v9inode));
return 0;
}
static const struct super_operations v9fs_super_ops = {
.alloc_inode = v9fs_alloc_inode,
.free_inode = v9fs_free_inode,
.statfs = simple_statfs,
.evict_inode = v9fs_evict_inode,
.show_options = v9fs_show_options,
.umount_begin = v9fs_umount_begin,
.write_inode = v9fs_write_inode,
};
static const struct super_operations v9fs_super_ops_dotl = {
.alloc_inode = v9fs_alloc_inode,
.free_inode = v9fs_free_inode,
.statfs = v9fs_statfs,
.drop_inode = v9fs_drop_inode,
.evict_inode = v9fs_evict_inode,
.show_options = v9fs_show_options,
.umount_begin = v9fs_umount_begin,
.write_inode = v9fs_write_inode_dotl,
};
struct file_system_type v9fs_fs_type = {
.name = "9p",
.mount = v9fs_mount,
.kill_sb = v9fs_kill_super,
.owner = THIS_MODULE,
.fs_flags = FS_RENAME_DOES_D_MOVE,
};
MODULE_ALIAS_FS("9p");