kernel-ark/fs/9p/v9fs.c
Eric Van Hensbergen e03abc0c96 9p: implement optional loose read cache
While cacheing is generally frowned upon in the 9p world, it has its
place -- particularly in situations where the remote file system is
exclusive and/or read-only.  The vacfs views of venti content addressable
store are a real-world instance of such a situation.  To facilitate higher
performance for these workloads (and eventually use the fscache patches),
we have enabled a "loose" cache mode which does not attempt to maintain
any form of consistency on the page-cache or dcache.  This results in over
two orders of magnitude performance improvement for cacheable block reads
in the Bonnie benchmark.  The more aggressive use of the dcache also seems
to improve metadata operational performance.

Signed-off-by: Eric Van Hensbergen <ericvh@gmail.com>
2007-02-18 10:16:10 -06:00

500 lines
11 KiB
C

/*
* linux/fs/9p/v9fs.c
*
* This file contains functions assisting in mapping VFS to 9P2000
*
* Copyright (C) 2004 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/sched.h>
#include <linux/parser.h>
#include <linux/idr.h>
#include "debug.h"
#include "v9fs.h"
#include "9p.h"
#include "v9fs_vfs.h"
#include "transport.h"
#include "mux.h"
/* TODO: sysfs or debugfs interface */
int v9fs_debug_level = 0; /* feature-rific global debug level */
/*
* Option Parsing (code inspired by NFS code)
*
*/
enum {
/* Options that take integer arguments */
Opt_port, Opt_msize, Opt_uid, Opt_gid, Opt_afid, Opt_debug,
Opt_rfdno, Opt_wfdno,
/* String options */
Opt_uname, Opt_remotename,
/* Options that take no arguments */
Opt_legacy, Opt_nodevmap, Opt_unix, Opt_tcp, Opt_fd,
/* Cache options */
Opt_cache_loose,
/* Error token */
Opt_err
};
static match_table_t tokens = {
{Opt_port, "port=%u"},
{Opt_msize, "msize=%u"},
{Opt_uid, "uid=%u"},
{Opt_gid, "gid=%u"},
{Opt_afid, "afid=%u"},
{Opt_rfdno, "rfdno=%u"},
{Opt_wfdno, "wfdno=%u"},
{Opt_debug, "debug=%x"},
{Opt_uname, "uname=%s"},
{Opt_remotename, "aname=%s"},
{Opt_unix, "proto=unix"},
{Opt_tcp, "proto=tcp"},
{Opt_fd, "proto=fd"},
{Opt_tcp, "tcp"},
{Opt_unix, "unix"},
{Opt_fd, "fd"},
{Opt_legacy, "noextend"},
{Opt_nodevmap, "nodevmap"},
{Opt_cache_loose, "cache=loose"},
{Opt_cache_loose, "loose"},
{Opt_err, NULL}
};
/*
* Parse option string.
*/
/**
* v9fs_parse_options - parse mount options into session structure
* @options: options string passed from mount
* @v9ses: existing v9fs session information
*
*/
static void v9fs_parse_options(char *options, struct v9fs_session_info *v9ses)
{
char *p;
substring_t args[MAX_OPT_ARGS];
int option;
int ret;
/* setup defaults */
v9ses->port = V9FS_PORT;
v9ses->maxdata = 9000;
v9ses->proto = PROTO_TCP;
v9ses->extended = 1;
v9ses->afid = ~0;
v9ses->debug = 0;
v9ses->rfdno = ~0;
v9ses->wfdno = ~0;
v9ses->cache = 0;
if (!options)
return;
while ((p = strsep(&options, ",")) != NULL) {
int token;
if (!*p)
continue;
token = match_token(p, tokens, args);
if (token < Opt_uname) {
if ((ret = match_int(&args[0], &option)) < 0) {
dprintk(DEBUG_ERROR,
"integer field, but no integer?\n");
continue;
}
}
switch (token) {
case Opt_port:
v9ses->port = option;
break;
case Opt_msize:
v9ses->maxdata = option;
break;
case Opt_uid:
v9ses->uid = option;
break;
case Opt_gid:
v9ses->gid = option;
break;
case Opt_afid:
v9ses->afid = option;
break;
case Opt_rfdno:
v9ses->rfdno = option;
break;
case Opt_wfdno:
v9ses->wfdno = option;
break;
case Opt_debug:
v9ses->debug = option;
break;
case Opt_tcp:
v9ses->proto = PROTO_TCP;
break;
case Opt_unix:
v9ses->proto = PROTO_UNIX;
break;
case Opt_fd:
v9ses->proto = PROTO_FD;
break;
case Opt_uname:
match_strcpy(v9ses->name, &args[0]);
break;
case Opt_remotename:
match_strcpy(v9ses->remotename, &args[0]);
break;
case Opt_legacy:
v9ses->extended = 0;
break;
case Opt_nodevmap:
v9ses->nodev = 1;
break;
case Opt_cache_loose:
v9ses->cache = CACHE_LOOSE;
break;
default:
continue;
}
}
}
/**
* v9fs_inode2v9ses - safely extract v9fs session info from super block
* @inode: inode to extract information from
*
* Paranoid function to extract v9ses information from superblock,
* if anything is missing it will report an error.
*
*/
struct v9fs_session_info *v9fs_inode2v9ses(struct inode *inode)
{
return (inode->i_sb->s_fs_info);
}
/**
* v9fs_get_idpool - allocate numeric id from pool
* @p - pool to allocate from
*
* XXX - This seems to be an awful generic function, should it be in idr.c with
* the lock included in struct idr?
*/
int v9fs_get_idpool(struct v9fs_idpool *p)
{
int i = 0;
int error;
retry:
if (idr_pre_get(&p->pool, GFP_KERNEL) == 0)
return 0;
if (down_interruptible(&p->lock) == -EINTR) {
eprintk(KERN_WARNING, "Interrupted while locking\n");
return -1;
}
/* no need to store exactly p, we just need something non-null */
error = idr_get_new(&p->pool, p, &i);
up(&p->lock);
if (error == -EAGAIN)
goto retry;
else if (error)
return -1;
return i;
}
/**
* v9fs_put_idpool - release numeric id from pool
* @p - pool to allocate from
*
* XXX - This seems to be an awful generic function, should it be in idr.c with
* the lock included in struct idr?
*/
void v9fs_put_idpool(int id, struct v9fs_idpool *p)
{
if (down_interruptible(&p->lock) == -EINTR) {
eprintk(KERN_WARNING, "Interrupted while locking\n");
return;
}
idr_remove(&p->pool, id);
up(&p->lock);
}
/**
* v9fs_check_idpool - check if the specified id is available
* @id - id to check
* @p - pool
*/
int v9fs_check_idpool(int id, struct v9fs_idpool *p)
{
return idr_find(&p->pool, id) != NULL;
}
/**
* v9fs_session_init - initialize session
* @v9ses: session information structure
* @dev_name: device being mounted
* @data: options
*
*/
int
v9fs_session_init(struct v9fs_session_info *v9ses,
const char *dev_name, char *data)
{
struct v9fs_fcall *fcall = NULL;
struct v9fs_transport *trans_proto;
int n = 0;
int newfid = -1;
int retval = -EINVAL;
struct v9fs_str *version;
v9ses->name = __getname();
if (!v9ses->name)
return -ENOMEM;
v9ses->remotename = __getname();
if (!v9ses->remotename) {
__putname(v9ses->name);
return -ENOMEM;
}
strcpy(v9ses->name, V9FS_DEFUSER);
strcpy(v9ses->remotename, V9FS_DEFANAME);
v9fs_parse_options(data, v9ses);
/* set global debug level */
v9fs_debug_level = v9ses->debug;
/* id pools that are session-dependent: fids and tags */
idr_init(&v9ses->fidpool.pool);
init_MUTEX(&v9ses->fidpool.lock);
switch (v9ses->proto) {
case PROTO_TCP:
trans_proto = &v9fs_trans_tcp;
break;
case PROTO_UNIX:
trans_proto = &v9fs_trans_unix;
*v9ses->remotename = 0;
break;
case PROTO_FD:
trans_proto = &v9fs_trans_fd;
*v9ses->remotename = 0;
break;
default:
printk(KERN_ERR "v9fs: Bad mount protocol %d\n", v9ses->proto);
retval = -ENOPROTOOPT;
goto SessCleanUp;
};
v9ses->transport = kmalloc(sizeof(*v9ses->transport), GFP_KERNEL);
if (!v9ses->transport) {
retval = -ENOMEM;
goto SessCleanUp;
}
memmove(v9ses->transport, trans_proto, sizeof(*v9ses->transport));
if ((retval = v9ses->transport->init(v9ses, dev_name, data)) < 0) {
eprintk(KERN_ERR, "problem initializing transport\n");
goto SessCleanUp;
}
v9ses->inprogress = 0;
v9ses->shutdown = 0;
v9ses->session_hung = 0;
v9ses->mux = v9fs_mux_init(v9ses->transport, v9ses->maxdata + V9FS_IOHDRSZ,
&v9ses->extended);
if (IS_ERR(v9ses->mux)) {
retval = PTR_ERR(v9ses->mux);
v9ses->mux = NULL;
dprintk(DEBUG_ERROR, "problem initializing mux\n");
goto SessCleanUp;
}
if (v9ses->afid == ~0) {
if (v9ses->extended)
retval =
v9fs_t_version(v9ses, v9ses->maxdata, "9P2000.u",
&fcall);
else
retval = v9fs_t_version(v9ses, v9ses->maxdata, "9P2000",
&fcall);
if (retval < 0) {
dprintk(DEBUG_ERROR, "v9fs_t_version failed\n");
goto FreeFcall;
}
version = &fcall->params.rversion.version;
if (version->len==8 && !memcmp(version->str, "9P2000.u", 8)) {
dprintk(DEBUG_9P, "9P2000 UNIX extensions enabled\n");
v9ses->extended = 1;
} else if (version->len==6 && !memcmp(version->str, "9P2000", 6)) {
dprintk(DEBUG_9P, "9P2000 legacy mode enabled\n");
v9ses->extended = 0;
} else {
retval = -EREMOTEIO;
goto FreeFcall;
}
n = fcall->params.rversion.msize;
kfree(fcall);
if (n < v9ses->maxdata)
v9ses->maxdata = n;
}
newfid = v9fs_get_idpool(&v9ses->fidpool);
if (newfid < 0) {
eprintk(KERN_WARNING, "couldn't allocate FID\n");
retval = -ENOMEM;
goto SessCleanUp;
}
/* it is a little bit ugly, but we have to prevent newfid */
/* being the same as afid, so if it is, get a new fid */
if (v9ses->afid != ~0 && newfid == v9ses->afid) {
newfid = v9fs_get_idpool(&v9ses->fidpool);
if (newfid < 0) {
eprintk(KERN_WARNING, "couldn't allocate FID\n");
retval = -ENOMEM;
goto SessCleanUp;
}
}
if ((retval =
v9fs_t_attach(v9ses, v9ses->name, v9ses->remotename, newfid,
v9ses->afid, NULL))
< 0) {
dprintk(DEBUG_ERROR, "cannot attach\n");
goto SessCleanUp;
}
if (v9ses->afid != ~0) {
dprintk(DEBUG_ERROR, "afid not equal to ~0\n");
if (v9fs_t_clunk(v9ses, v9ses->afid))
dprintk(DEBUG_ERROR, "clunk failed\n");
}
return newfid;
FreeFcall:
kfree(fcall);
SessCleanUp:
v9fs_session_close(v9ses);
return retval;
}
/**
* v9fs_session_close - shutdown a session
* @v9ses: session information structure
*
*/
void v9fs_session_close(struct v9fs_session_info *v9ses)
{
if (v9ses->mux) {
v9fs_mux_destroy(v9ses->mux);
v9ses->mux = NULL;
}
if (v9ses->transport) {
v9ses->transport->close(v9ses->transport);
kfree(v9ses->transport);
v9ses->transport = NULL;
}
__putname(v9ses->name);
__putname(v9ses->remotename);
}
/**
* v9fs_session_cancel - mark transport as disconnected
* and cancel all pending requests.
*/
void v9fs_session_cancel(struct v9fs_session_info *v9ses) {
dprintk(DEBUG_ERROR, "cancel session %p\n", v9ses);
v9ses->transport->status = Disconnected;
v9fs_mux_cancel(v9ses->mux, -EIO);
}
extern int v9fs_error_init(void);
/**
* v9fs_init - Initialize module
*
*/
static int __init init_v9fs(void)
{
int ret;
v9fs_error_init();
printk(KERN_INFO "Installing v9fs 9p2000 file system support\n");
ret = v9fs_mux_global_init();
if (ret) {
printk(KERN_WARNING "v9fs: starting mux failed\n");
return ret;
}
ret = register_filesystem(&v9fs_fs_type);
if (ret) {
printk(KERN_WARNING "v9fs: registering file system failed\n");
v9fs_mux_global_exit();
}
return ret;
}
/**
* v9fs_init - shutdown module
*
*/
static void __exit exit_v9fs(void)
{
v9fs_mux_global_exit();
unregister_filesystem(&v9fs_fs_type);
}
module_init(init_v9fs)
module_exit(exit_v9fs)
MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
MODULE_AUTHOR("Ron Minnich <rminnich@lanl.gov>");
MODULE_LICENSE("GPL");