android_kernel_sony_msm8994/fs/9p/vfs_file.c
Latchesar Ionkov 41e5a6ac80 [PATCH] v9fs: signal handling fixes
Multiple races can happen when v9fs is interrupted by a signal and Tflush
message is sent to the server.  After v9fs sends Tflush it doesn't wait
until it receives Rflush, and possibly the response of the original
message.  This behavior may confuse v9fs what fids are allocated by the
file server.

This patch fixes the races and the fid allocation.

Signed-off-by: Latchesar Ionkov <lucho@ionkov.net>
Cc: Eric Van Hensbergen <ericvh@hera.kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-05-15 11:20:56 -07:00

283 lines
6.3 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 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/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 *vfid;
struct v9fs_fcall *fcall = NULL;
int omode;
int fid = V9FS_NOFID;
int err;
dprintk(DEBUG_VFS, "inode: %p file: %p \n", inode, file);
vfid = v9fs_fid_lookup(file->f_dentry);
if (!vfid) {
dprintk(DEBUG_ERROR, "Couldn't resolve fid from dentry\n");
return -EBADF;
}
fid = v9fs_get_idpool(&v9ses->fidpool);
if (fid < 0) {
eprintk(KERN_WARNING, "newfid fails!\n");
return -ENOSPC;
}
err = v9fs_t_walk(v9ses, vfid->fid, fid, NULL, &fcall);
if (err < 0) {
dprintk(DEBUG_ERROR, "rewalk didn't work\n");
if (fcall && fcall->id == RWALK)
goto clunk_fid;
else {
v9fs_put_idpool(fid, &v9ses->fidpool);
goto free_fcall;
}
}
kfree(fcall);
/* TODO: do special things for O_EXCL, O_NOFOLLOW, O_SYNC */
/* translate open mode appropriately */
omode = v9fs_uflags2omode(file->f_flags);
err = v9fs_t_open(v9ses, fid, omode, &fcall);
if (err < 0) {
PRINT_FCALL_ERROR("open failed", fcall);
goto clunk_fid;
}
vfid = kmalloc(sizeof(struct v9fs_fid), GFP_KERNEL);
if (vfid == NULL) {
dprintk(DEBUG_ERROR, "out of memory\n");
err = -ENOMEM;
goto clunk_fid;
}
file->private_data = vfid;
vfid->fid = fid;
vfid->fidopen = 1;
vfid->fidclunked = 0;
vfid->iounit = fcall->params.ropen.iounit;
vfid->rdir_pos = 0;
vfid->rdir_fcall = NULL;
vfid->filp = file;
kfree(fcall);
return 0;
clunk_fid:
v9fs_t_clunk(v9ses, fid);
free_fcall:
kfree(fcall);
return err;
}
/**
* 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_write_and_wait(inode->i_mapping);
invalidate_inode_pages(&inode->i_data);
}
return res;
}
/**
* 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)
{
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;
int n;
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;
n = copy_to_user(data, fcall->params.rread.data, result);
if (n) {
dprintk(DEBUG_ERROR, "Problem copying to user %d\n", n);
kfree(fcall);
return -EFAULT;
}
count -= result;
data += result;
total += result;
kfree(fcall);
if (result < rsize)
break;
} 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)
{
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", data, (int)count,
(int)*offset);
rsize = v9ses->maxdata - V9FS_IOHDRSZ;
if (v9fid->iounit != 0 && rsize > v9fid->iounit)
rsize = v9fid->iounit;
do {
if (count < rsize)
rsize = count;
result = v9fs_t_write(v9ses, fid, *offset, rsize, data, &fcall);
if (result < 0) {
PRINT_FCALL_ERROR("error while writing", fcall);
kfree(fcall);
return result;
} else
*offset += result;
kfree(fcall);
fcall = NULL;
if (result != rsize) {
eprintk(KERN_ERR,
"short write: v9fs_t_write returned %d\n",
result);
break;
}
count -= result;
data += result;
total += result;
} while (count);
invalidate_inode_pages2(inode->i_mapping);
return total;
}
const 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,
.mmap = generic_file_mmap,
};