kernel-ark/fs/9p/vfs_file.c
Latchesar Ionkov 0b8dd17762 [PATCH] v9fs: fix races in fid allocation
Fid management cleanup.  The patch attempts to fix the races in dentry's
fid management.

Dentries don't keep the opened fids anymore, they are moved to the file
structs.  Ideally there should be no more than one fid with fidcreate equal
to zero in the dentry's list of fids.

v9fs_fid_create initializes the important fields (fid, fidcreated) before
v9fs_fid is added to the list.  v9fs_fid_lookup returns only fids that are
not created by v9fs_create.  v9fs_fid_get_created returns the fid created
by the same process by v9fs_create (if any) and removes it from dentry's
list

Signed-off-by: Latchesar Ionkov <lucho@ionkov.net>
Cc: Eric Van Hensbergen <ericvh@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-28 07:46:40 -07:00

370 lines
8.1 KiB
C

/*
* linux/fs/9p/vfs_file.c
*
* This file contians vfs file ops for 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 as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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/file.h>
#include <linux/stat.h>
#include <linux/string.h>
#include <linux/smp_lock.h>
#include <linux/inet.h>
#include <linux/version.h>
#include <linux/list.h>
#include <asm/uaccess.h>
#include <linux/idr.h>
#include "debug.h"
#include "v9fs.h"
#include "9p.h"
#include "v9fs_vfs.h"
#include "fid.h"
/**
* v9fs_file_open - open a file (or directory)
* @inode: inode to be opened
* @file: file being opened
*
*/
int v9fs_file_open(struct inode *inode, struct file *file)
{
struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
struct v9fs_fid *v9fid, *fid;
struct v9fs_fcall *fcall = NULL;
int open_mode = 0;
unsigned int iounit = 0;
int newfid = -1;
long result = -1;
dprintk(DEBUG_VFS, "inode: %p file: %p \n", inode, file);
v9fid = v9fs_fid_get_created(file->f_dentry);
if (!v9fid)
v9fid = v9fs_fid_lookup(file->f_dentry);
if (!v9fid) {
dprintk(DEBUG_ERROR, "Couldn't resolve fid from dentry\n");
return -EBADF;
}
if (!v9fid->fidcreate) {
fid = kmalloc(sizeof(struct v9fs_fid), GFP_KERNEL);
if (fid == NULL) {
dprintk(DEBUG_ERROR, "Out of Memory\n");
return -ENOMEM;
}
fid->fidopen = 0;
fid->fidcreate = 0;
fid->fidclunked = 0;
fid->iounit = 0;
fid->v9ses = v9ses;
newfid = v9fs_get_idpool(&v9ses->fidpool);
if (newfid < 0) {
eprintk(KERN_WARNING, "newfid fails!\n");
return -ENOSPC;
}
result =
v9fs_t_walk(v9ses, v9fid->fid, newfid, NULL, NULL);
if (result < 0) {
v9fs_put_idpool(newfid, &v9ses->fidpool);
dprintk(DEBUG_ERROR, "rewalk didn't work\n");
return -EBADF;
}
fid->fid = newfid;
v9fid = fid;
/* TODO: do special things for O_EXCL, O_NOFOLLOW, O_SYNC */
/* translate open mode appropriately */
open_mode = file->f_flags & 0x3;
if (file->f_flags & O_EXCL)
open_mode |= V9FS_OEXCL;
if (v9ses->extended) {
if (file->f_flags & O_TRUNC)
open_mode |= V9FS_OTRUNC;
if (file->f_flags & O_APPEND)
open_mode |= V9FS_OAPPEND;
}
result = v9fs_t_open(v9ses, newfid, open_mode, &fcall);
if (result < 0) {
dprintk(DEBUG_ERROR,
"open failed, open_mode 0x%x: %s\n", open_mode,
FCALL_ERROR(fcall));
kfree(fcall);
return result;
}
iounit = fcall->params.ropen.iounit;
kfree(fcall);
} else {
/* create case */
newfid = v9fid->fid;
iounit = v9fid->iounit;
v9fid->fidcreate = 0;
}
file->private_data = v9fid;
v9fid->rdir_pos = 0;
v9fid->rdir_fcall = NULL;
v9fid->fidopen = 1;
v9fid->filp = file;
v9fid->iounit = iounit;
return 0;
}
/**
* v9fs_file_lock - lock a file (or directory)
* @inode: inode to be opened
* @file: file being opened
*
* XXX - this looks like a local only lock, we should extend into 9P
* by using open exclusive
*/
static int v9fs_file_lock(struct file *filp, int cmd, struct file_lock *fl)
{
int res = 0;
struct inode *inode = filp->f_dentry->d_inode;
dprintk(DEBUG_VFS, "filp: %p lock: %p\n", filp, fl);
/* No mandatory locks */
if ((inode->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID)
return -ENOLCK;
if ((IS_SETLK(cmd) || IS_SETLKW(cmd)) && fl->fl_type != F_UNLCK) {
filemap_fdatawrite(inode->i_mapping);
filemap_fdatawait(inode->i_mapping);
invalidate_inode_pages(&inode->i_data);
}
return res;
}
/**
* v9fs_read - read from a file (internal)
* @filep: file pointer to read
* @data: data buffer to read data into
* @count: size of buffer
* @offset: offset at which to read data
*
*/
static ssize_t
v9fs_read(struct file *filp, char *buffer, size_t count, loff_t * offset)
{
struct inode *inode = filp->f_dentry->d_inode;
struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
struct v9fs_fid *v9f = filp->private_data;
struct v9fs_fcall *fcall = NULL;
int fid = v9f->fid;
int rsize = 0;
int result = 0;
int total = 0;
dprintk(DEBUG_VFS, "\n");
rsize = v9ses->maxdata - V9FS_IOHDRSZ;
if (v9f->iounit != 0 && rsize > v9f->iounit)
rsize = v9f->iounit;
do {
if (count < rsize)
rsize = count;
result = v9fs_t_read(v9ses, fid, *offset, rsize, &fcall);
if (result < 0) {
printk(KERN_ERR "9P2000: v9fs_t_read returned %d\n",
result);
kfree(fcall);
return total;
} else
*offset += result;
/* XXX - extra copy */
memcpy(buffer, fcall->params.rread.data, result);
count -= result;
buffer += result;
total += result;
kfree(fcall);
if (result < rsize)
break;
} while (count);
return total;
}
/**
* v9fs_file_read - read from a file
* @filep: file pointer to read
* @data: data buffer to read data into
* @count: size of buffer
* @offset: offset at which to read data
*
*/
static ssize_t
v9fs_file_read(struct file *filp, char __user * data, size_t count,
loff_t * offset)
{
int retval = -1;
int ret = 0;
char *buffer;
buffer = kmalloc(count, GFP_KERNEL);
if (!buffer)
return -ENOMEM;
retval = v9fs_read(filp, buffer, count, offset);
if (retval > 0) {
if ((ret = copy_to_user(data, buffer, retval)) != 0) {
dprintk(DEBUG_ERROR, "Problem copying to user %d\n",
ret);
retval = ret;
}
}
kfree(buffer);
return retval;
}
/**
* v9fs_write - write to a file
* @filep: file pointer to write
* @data: data buffer to write data from
* @count: size of buffer
* @offset: offset at which to write data
*
*/
static ssize_t
v9fs_write(struct file *filp, char *buffer, size_t count, loff_t * offset)
{
struct inode *inode = filp->f_dentry->d_inode;
struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
struct v9fs_fid *v9fid = filp->private_data;
struct v9fs_fcall *fcall;
int fid = v9fid->fid;
int result = -EIO;
int rsize = 0;
int total = 0;
dprintk(DEBUG_VFS, "data %p count %d offset %x\n", buffer, (int)count,
(int)*offset);
rsize = v9ses->maxdata - V9FS_IOHDRSZ;
if (v9fid->iounit != 0 && rsize > v9fid->iounit)
rsize = v9fid->iounit;
dump_data(buffer, count);
do {
if (count < rsize)
rsize = count;
result =
v9fs_t_write(v9ses, fid, *offset, rsize, buffer, &fcall);
if (result < 0) {
eprintk(KERN_ERR, "error while writing: %s(%d)\n",
FCALL_ERROR(fcall), result);
kfree(fcall);
return result;
} else
*offset += result;
kfree(fcall);
if (result != rsize) {
eprintk(KERN_ERR,
"short write: v9fs_t_write returned %d\n",
result);
break;
}
count -= result;
buffer += result;
total += result;
} while (count);
return total;
}
/**
* v9fs_file_write - write to a file
* @filep: file pointer to write
* @data: data buffer to write data from
* @count: size of buffer
* @offset: offset at which to write data
*
*/
static ssize_t
v9fs_file_write(struct file *filp, const char __user * data,
size_t count, loff_t * offset)
{
int ret = -1;
char *buffer;
buffer = kmalloc(count, GFP_KERNEL);
if (buffer == NULL)
return -ENOMEM;
ret = copy_from_user(buffer, data, count);
if (ret) {
dprintk(DEBUG_ERROR, "Problem copying from user\n");
ret = -EFAULT;
} else {
ret = v9fs_write(filp, buffer, count, offset);
}
kfree(buffer);
return ret;
}
struct file_operations v9fs_file_operations = {
.llseek = generic_file_llseek,
.read = v9fs_file_read,
.write = v9fs_file_write,
.open = v9fs_file_open,
.release = v9fs_dir_release,
.lock = v9fs_file_lock,
};