kernel-ark/fs/9p/vfs_dir.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

224 lines
4.9 KiB
C

/*
* linux/fs/9p/vfs_dir.c
*
* This file contains vfs directory ops for the 9P2000 protocol.
*
* 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/idr.h>
#include "debug.h"
#include "v9fs.h"
#include "9p.h"
#include "v9fs_vfs.h"
#include "conv.h"
#include "fid.h"
/**
* dt_type - return file type
* @mistat: mistat structure
*
*/
static inline int dt_type(struct v9fs_stat *mistat)
{
unsigned long perm = mistat->mode;
int rettype = DT_REG;
if (perm & V9FS_DMDIR)
rettype = DT_DIR;
if (perm & V9FS_DMSYMLINK)
rettype = DT_LNK;
return rettype;
}
/**
* v9fs_dir_readdir - read a directory
* @filep: opened file structure
* @dirent: directory structure ???
* @filldir: function to populate directory structure ???
*
*/
static int v9fs_dir_readdir(struct file *filp, void *dirent, filldir_t filldir)
{
struct v9fs_fcall *fcall = NULL;
struct inode *inode = filp->f_dentry->d_inode;
struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
struct v9fs_fid *file = filp->private_data;
unsigned int i, n;
int fid = -1;
int ret = 0;
struct v9fs_stat *mi = NULL;
int over = 0;
dprintk(DEBUG_VFS, "name %s\n", filp->f_dentry->d_name.name);
fid = file->fid;
mi = kmalloc(v9ses->maxdata, GFP_KERNEL);
if (!mi)
return -ENOMEM;
if (file->rdir_fcall && (filp->f_pos != file->rdir_pos)) {
kfree(file->rdir_fcall);
file->rdir_fcall = NULL;
}
if (file->rdir_fcall) {
n = file->rdir_fcall->params.rread.count;
i = file->rdir_fpos;
while (i < n) {
int s = v9fs_deserialize_stat(v9ses,
file->rdir_fcall->params.rread.data + i,
n - i, mi, v9ses->maxdata);
if (s == 0) {
dprintk(DEBUG_ERROR,
"error while deserializing mistat\n");
ret = -EIO;
goto FreeStructs;
}
over = filldir(dirent, mi->name, strlen(mi->name),
filp->f_pos, v9fs_qid2ino(&mi->qid),
dt_type(mi));
if (over) {
file->rdir_fpos = i;
file->rdir_pos = filp->f_pos;
break;
}
i += s;
filp->f_pos += s;
}
if (!over) {
kfree(file->rdir_fcall);
file->rdir_fcall = NULL;
}
}
while (!over) {
ret = v9fs_t_read(v9ses, fid, filp->f_pos,
v9ses->maxdata-V9FS_IOHDRSZ, &fcall);
if (ret < 0) {
dprintk(DEBUG_ERROR, "error while reading: %d: %p\n",
ret, fcall);
goto FreeStructs;
} else if (ret == 0)
break;
n = ret;
i = 0;
while (i < n) {
int s = v9fs_deserialize_stat(v9ses,
fcall->params.rread.data + i, n - i, mi,
v9ses->maxdata);
if (s == 0) {
dprintk(DEBUG_ERROR,
"error while deserializing mistat\n");
return -EIO;
}
over = filldir(dirent, mi->name, strlen(mi->name),
filp->f_pos, v9fs_qid2ino(&mi->qid),
dt_type(mi));
if (over) {
file->rdir_fcall = fcall;
file->rdir_fpos = i;
file->rdir_pos = filp->f_pos;
fcall = NULL;
break;
}
i += s;
filp->f_pos += s;
}
kfree(fcall);
}
FreeStructs:
kfree(fcall);
kfree(mi);
return ret;
}
/**
* v9fs_dir_release - close a directory
* @inode: inode of the directory
* @filp: file pointer to a directory
*
*/
int v9fs_dir_release(struct inode *inode, struct file *filp)
{
struct v9fs_session_info *v9ses = v9fs_inode2v9ses(inode);
struct v9fs_fid *fid = filp->private_data;
int fidnum = -1;
dprintk(DEBUG_VFS, "inode: %p filp: %p fid: %d\n", inode, filp,
fid->fid);
fidnum = fid->fid;
filemap_fdatawrite(inode->i_mapping);
filemap_fdatawait(inode->i_mapping);
if (fidnum >= 0) {
dprintk(DEBUG_VFS, "fidopen: %d v9f->fid: %d\n", fid->fidopen,
fid->fid);
if (v9fs_t_clunk(v9ses, fidnum, NULL))
dprintk(DEBUG_ERROR, "clunk failed\n");
v9fs_put_idpool(fid->fid, &v9ses->fidpool);
kfree(fid->rdir_fcall);
kfree(fid);
filp->private_data = NULL;
}
d_drop(filp->f_dentry);
return 0;
}
struct file_operations v9fs_dir_operations = {
.read = generic_read_dir,
.readdir = v9fs_dir_readdir,
.open = v9fs_file_open,
.release = v9fs_dir_release,
};