kernel-ark/fs/gfs2/export.c
Steven Whitehouse acf7e2444a GFS2: Be extra careful about deallocating inodes
There is a potential race in the inode deallocation code if two
nodes try to deallocate the same inode at the same time. Most of
the issue is solved by the iopen locking. There is still a small
window which is not covered by the iopen lock. This patches fixes
that and also makes the deallocation code more robust in the face of
any errors in the rgrp bitmaps, or erroneous iopen callbacks from
other nodes.

This does introduce one extra disk read, but that is generally not
an issue since its the same block that must be written to later
in the deallocation process. The total disk accesses therefore stay
the same,

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2009-09-08 18:00:30 +01:00

258 lines
5.8 KiB
C

/*
* Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
* Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
* of the GNU General Public License version 2.
*/
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>
#include <linux/exportfs.h>
#include <linux/gfs2_ondisk.h>
#include <linux/crc32.h>
#include "gfs2.h"
#include "incore.h"
#include "dir.h"
#include "glock.h"
#include "glops.h"
#include "inode.h"
#include "super.h"
#include "rgrp.h"
#include "util.h"
#define GFS2_SMALL_FH_SIZE 4
#define GFS2_LARGE_FH_SIZE 8
#define GFS2_OLD_FH_SIZE 10
static int gfs2_encode_fh(struct dentry *dentry, __u32 *p, int *len,
int connectable)
{
__be32 *fh = (__force __be32 *)p;
struct inode *inode = dentry->d_inode;
struct super_block *sb = inode->i_sb;
struct gfs2_inode *ip = GFS2_I(inode);
if (*len < GFS2_SMALL_FH_SIZE ||
(connectable && *len < GFS2_LARGE_FH_SIZE))
return 255;
fh[0] = cpu_to_be32(ip->i_no_formal_ino >> 32);
fh[1] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
fh[2] = cpu_to_be32(ip->i_no_addr >> 32);
fh[3] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);
*len = GFS2_SMALL_FH_SIZE;
if (!connectable || inode == sb->s_root->d_inode)
return *len;
spin_lock(&dentry->d_lock);
inode = dentry->d_parent->d_inode;
ip = GFS2_I(inode);
igrab(inode);
spin_unlock(&dentry->d_lock);
fh[4] = cpu_to_be32(ip->i_no_formal_ino >> 32);
fh[5] = cpu_to_be32(ip->i_no_formal_ino & 0xFFFFFFFF);
fh[6] = cpu_to_be32(ip->i_no_addr >> 32);
fh[7] = cpu_to_be32(ip->i_no_addr & 0xFFFFFFFF);
*len = GFS2_LARGE_FH_SIZE;
iput(inode);
return *len;
}
struct get_name_filldir {
struct gfs2_inum_host inum;
char *name;
};
static int get_name_filldir(void *opaque, const char *name, int length,
loff_t offset, u64 inum, unsigned int type)
{
struct get_name_filldir *gnfd = opaque;
if (inum != gnfd->inum.no_addr)
return 0;
memcpy(gnfd->name, name, length);
gnfd->name[length] = 0;
return 1;
}
static int gfs2_get_name(struct dentry *parent, char *name,
struct dentry *child)
{
struct inode *dir = parent->d_inode;
struct inode *inode = child->d_inode;
struct gfs2_inode *dip, *ip;
struct get_name_filldir gnfd;
struct gfs2_holder gh;
u64 offset = 0;
int error;
if (!dir)
return -EINVAL;
if (!S_ISDIR(dir->i_mode) || !inode)
return -EINVAL;
dip = GFS2_I(dir);
ip = GFS2_I(inode);
*name = 0;
gnfd.inum.no_addr = ip->i_no_addr;
gnfd.inum.no_formal_ino = ip->i_no_formal_ino;
gnfd.name = name;
error = gfs2_glock_nq_init(dip->i_gl, LM_ST_SHARED, 0, &gh);
if (error)
return error;
error = gfs2_dir_read(dir, &offset, &gnfd, get_name_filldir);
gfs2_glock_dq_uninit(&gh);
if (!error && !*name)
error = -ENOENT;
return error;
}
static struct dentry *gfs2_get_parent(struct dentry *child)
{
struct qstr dotdot;
struct dentry *dentry;
/*
* XXX(hch): it would be a good idea to keep this around as a
* static variable.
*/
gfs2_str2qstr(&dotdot, "..");
dentry = d_obtain_alias(gfs2_lookupi(child->d_inode, &dotdot, 1));
if (!IS_ERR(dentry))
dentry->d_op = &gfs2_dops;
return dentry;
}
static struct dentry *gfs2_get_dentry(struct super_block *sb,
struct gfs2_inum_host *inum)
{
struct gfs2_sbd *sdp = sb->s_fs_info;
struct gfs2_holder i_gh;
struct inode *inode;
struct dentry *dentry;
int error;
inode = gfs2_ilookup(sb, inum->no_addr);
if (inode) {
if (GFS2_I(inode)->i_no_formal_ino != inum->no_formal_ino) {
iput(inode);
return ERR_PTR(-ESTALE);
}
goto out_inode;
}
error = gfs2_glock_nq_num(sdp, inum->no_addr, &gfs2_inode_glops,
LM_ST_SHARED, LM_FLAG_ANY, &i_gh);
if (error)
return ERR_PTR(error);
error = gfs2_check_blk_type(sdp, inum->no_addr, GFS2_BLKST_DINODE);
if (error)
goto fail;
inode = gfs2_inode_lookup(sb, DT_UNKNOWN, inum->no_addr, 0, 0);
if (IS_ERR(inode)) {
error = PTR_ERR(inode);
goto fail;
}
error = gfs2_inode_refresh(GFS2_I(inode));
if (error) {
iput(inode);
goto fail;
}
/* Pick up the works we bypass in gfs2_inode_lookup */
if (inode->i_state & I_NEW)
gfs2_set_iop(inode);
if (GFS2_I(inode)->i_no_formal_ino != inum->no_formal_ino) {
iput(inode);
goto fail;
}
error = -EIO;
if (GFS2_I(inode)->i_diskflags & GFS2_DIF_SYSTEM) {
iput(inode);
goto fail;
}
gfs2_glock_dq_uninit(&i_gh);
out_inode:
dentry = d_obtain_alias(inode);
if (!IS_ERR(dentry))
dentry->d_op = &gfs2_dops;
return dentry;
fail:
gfs2_glock_dq_uninit(&i_gh);
return ERR_PTR(error);
}
static struct dentry *gfs2_fh_to_dentry(struct super_block *sb, struct fid *fid,
int fh_len, int fh_type)
{
struct gfs2_inum_host this;
__be32 *fh = (__force __be32 *)fid->raw;
switch (fh_type) {
case GFS2_SMALL_FH_SIZE:
case GFS2_LARGE_FH_SIZE:
case GFS2_OLD_FH_SIZE:
this.no_formal_ino = ((u64)be32_to_cpu(fh[0])) << 32;
this.no_formal_ino |= be32_to_cpu(fh[1]);
this.no_addr = ((u64)be32_to_cpu(fh[2])) << 32;
this.no_addr |= be32_to_cpu(fh[3]);
return gfs2_get_dentry(sb, &this);
default:
return NULL;
}
}
static struct dentry *gfs2_fh_to_parent(struct super_block *sb, struct fid *fid,
int fh_len, int fh_type)
{
struct gfs2_inum_host parent;
__be32 *fh = (__force __be32 *)fid->raw;
switch (fh_type) {
case GFS2_LARGE_FH_SIZE:
case GFS2_OLD_FH_SIZE:
parent.no_formal_ino = ((u64)be32_to_cpu(fh[4])) << 32;
parent.no_formal_ino |= be32_to_cpu(fh[5]);
parent.no_addr = ((u64)be32_to_cpu(fh[6])) << 32;
parent.no_addr |= be32_to_cpu(fh[7]);
return gfs2_get_dentry(sb, &parent);
default:
return NULL;
}
}
const struct export_operations gfs2_export_ops = {
.encode_fh = gfs2_encode_fh,
.fh_to_dentry = gfs2_fh_to_dentry,
.fh_to_parent = gfs2_fh_to_parent,
.get_name = gfs2_get_name,
.get_parent = gfs2_get_parent,
};