linux/fs/gfs2/trans.c
Benjamin Marzinski 96e5d1d3ad GFS2: Test bufdata with buffer locked and gfs2_log_lock held
In gfs2_trans_add_bh(), gfs2 was testing if a there was a bd attached to the
buffer without having the gfs2_log_lock held. It was then assuming it would
stay attached for the rest of the function. However, without either the log
lock being held of the buffer locked, __gfs2_ail_flush() could detach bd at any
time.  This patch moves the locking before the test.  If there isn't a bd
already attached, gfs2 can safely allocate one and attach it before locking.
There is no way that the newly allocated bd could be on the ail list,
and thus no way for __gfs2_ail_flush() to detach it.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
2012-11-07 09:43:03 +00:00

206 lines
5.0 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/sched.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>
#include <linux/kallsyms.h>
#include <linux/gfs2_ondisk.h>
#include "gfs2.h"
#include "incore.h"
#include "glock.h"
#include "log.h"
#include "lops.h"
#include "meta_io.h"
#include "trans.h"
#include "util.h"
#include "trace_gfs2.h"
int gfs2_trans_begin(struct gfs2_sbd *sdp, unsigned int blocks,
unsigned int revokes)
{
struct gfs2_trans *tr;
int error;
BUG_ON(current->journal_info);
BUG_ON(blocks == 0 && revokes == 0);
if (!test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags))
return -EROFS;
tr = kzalloc(sizeof(struct gfs2_trans), GFP_NOFS);
if (!tr)
return -ENOMEM;
tr->tr_ip = (unsigned long)__builtin_return_address(0);
tr->tr_blocks = blocks;
tr->tr_revokes = revokes;
tr->tr_reserved = 1;
if (blocks)
tr->tr_reserved += 6 + blocks;
if (revokes)
tr->tr_reserved += gfs2_struct2blk(sdp, revokes,
sizeof(u64));
sb_start_intwrite(sdp->sd_vfs);
gfs2_holder_init(sdp->sd_trans_gl, LM_ST_SHARED, 0, &tr->tr_t_gh);
error = gfs2_glock_nq(&tr->tr_t_gh);
if (error)
goto fail_holder_uninit;
error = gfs2_log_reserve(sdp, tr->tr_reserved);
if (error)
goto fail_gunlock;
current->journal_info = tr;
return 0;
fail_gunlock:
gfs2_glock_dq(&tr->tr_t_gh);
fail_holder_uninit:
sb_end_intwrite(sdp->sd_vfs);
gfs2_holder_uninit(&tr->tr_t_gh);
kfree(tr);
return error;
}
/**
* gfs2_log_release - Release a given number of log blocks
* @sdp: The GFS2 superblock
* @blks: The number of blocks
*
*/
static void gfs2_log_release(struct gfs2_sbd *sdp, unsigned int blks)
{
atomic_add(blks, &sdp->sd_log_blks_free);
trace_gfs2_log_blocks(sdp, blks);
gfs2_assert_withdraw(sdp, atomic_read(&sdp->sd_log_blks_free) <=
sdp->sd_jdesc->jd_blocks);
up_read(&sdp->sd_log_flush_lock);
}
static void gfs2_print_trans(const struct gfs2_trans *tr)
{
print_symbol(KERN_WARNING "GFS2: Transaction created at: %s\n", tr->tr_ip);
printk(KERN_WARNING "GFS2: blocks=%u revokes=%u reserved=%u touched=%d\n",
tr->tr_blocks, tr->tr_revokes, tr->tr_reserved, tr->tr_touched);
printk(KERN_WARNING "GFS2: Buf %u/%u Databuf %u/%u Revoke %u/%u\n",
tr->tr_num_buf_new, tr->tr_num_buf_rm,
tr->tr_num_databuf_new, tr->tr_num_databuf_rm,
tr->tr_num_revoke, tr->tr_num_revoke_rm);
}
void gfs2_trans_end(struct gfs2_sbd *sdp)
{
struct gfs2_trans *tr = current->journal_info;
s64 nbuf;
BUG_ON(!tr);
current->journal_info = NULL;
if (!tr->tr_touched) {
gfs2_log_release(sdp, tr->tr_reserved);
if (tr->tr_t_gh.gh_gl) {
gfs2_glock_dq(&tr->tr_t_gh);
gfs2_holder_uninit(&tr->tr_t_gh);
kfree(tr);
}
sb_end_intwrite(sdp->sd_vfs);
return;
}
nbuf = tr->tr_num_buf_new + tr->tr_num_databuf_new;
nbuf -= tr->tr_num_buf_rm;
nbuf -= tr->tr_num_databuf_rm;
if (gfs2_assert_withdraw(sdp, (nbuf <= tr->tr_blocks) &&
(tr->tr_num_revoke <= tr->tr_revokes)))
gfs2_print_trans(tr);
gfs2_log_commit(sdp, tr);
if (tr->tr_t_gh.gh_gl) {
gfs2_glock_dq(&tr->tr_t_gh);
gfs2_holder_uninit(&tr->tr_t_gh);
kfree(tr);
}
if (sdp->sd_vfs->s_flags & MS_SYNCHRONOUS)
gfs2_log_flush(sdp, NULL);
sb_end_intwrite(sdp->sd_vfs);
}
/**
* gfs2_trans_add_bh - Add a to-be-modified buffer to the current transaction
* @gl: the glock the buffer belongs to
* @bh: The buffer to add
* @meta: True in the case of adding metadata
*
*/
void gfs2_trans_add_bh(struct gfs2_glock *gl, struct buffer_head *bh, int meta)
{
struct gfs2_sbd *sdp = gl->gl_sbd;
struct gfs2_bufdata *bd;
lock_buffer(bh);
gfs2_log_lock(sdp);
bd = bh->b_private;
if (bd)
gfs2_assert(sdp, bd->bd_gl == gl);
else {
gfs2_log_unlock(sdp);
unlock_buffer(bh);
gfs2_attach_bufdata(gl, bh, meta);
bd = bh->b_private;
lock_buffer(bh);
gfs2_log_lock(sdp);
}
lops_add(sdp, bd);
gfs2_log_unlock(sdp);
unlock_buffer(bh);
}
void gfs2_trans_add_revoke(struct gfs2_sbd *sdp, struct gfs2_bufdata *bd)
{
BUG_ON(!list_empty(&bd->bd_list));
BUG_ON(!list_empty(&bd->bd_ail_st_list));
BUG_ON(!list_empty(&bd->bd_ail_gl_list));
lops_init_le(bd, &gfs2_revoke_lops);
lops_add(sdp, bd);
}
void gfs2_trans_add_unrevoke(struct gfs2_sbd *sdp, u64 blkno, unsigned int len)
{
struct gfs2_bufdata *bd, *tmp;
struct gfs2_trans *tr = current->journal_info;
unsigned int n = len;
gfs2_log_lock(sdp);
list_for_each_entry_safe(bd, tmp, &sdp->sd_log_le_revoke, bd_list) {
if ((bd->bd_blkno >= blkno) && (bd->bd_blkno < (blkno + len))) {
list_del_init(&bd->bd_list);
gfs2_assert_withdraw(sdp, sdp->sd_log_num_revoke);
sdp->sd_log_num_revoke--;
kmem_cache_free(gfs2_bufdata_cachep, bd);
tr->tr_num_revoke_rm++;
if (--n == 0)
break;
}
}
gfs2_log_unlock(sdp);
}