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fe3e397668
linux/fs/gfs2/trans.c
Andreas Gruenbacher fe3e397668 gfs2: Rework the log space allocation logic 
The current log space allocation logic is hard to understand or extend.
The principle it that when the log is flushed, we may or may not have a
transaction active that has space allocated in the log.  To deal with
that, we set aside a magical number of blocks to be used in case we
don't have an active transaction.  It isn't clear that the pool will
always be big enough.  In addition, we can't return unused log space at
the end of a transaction, so the number of blocks allocated must exactly
match the number of blocks used.

Simplify this as follows:
 * When transactions are allocated or merged, always reserve enough
   blocks to flush the transaction (err on the safe side).
 * In gfs2_log_flush, return any allocated blocks that haven't been used.
 * Maintain a pool of spare blocks big enough to do one log flush, as
   before.
 * In gfs2_log_flush, when we have no active transaction, allocate a
   suitable number of blocks.  For that, use the spare pool when
   called from logd, and leave the pool alone otherwise.  This means
   that when the log is almost full, logd will still be able to do one
   more log flush, which will result in more log space becoming
   available.

This will make the log space allocator code easier to work with in
the future.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
2021-02-22 21:16:22 +01:00

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
* Copyright (C) 2004-2006 Red Hat, Inc. All rights reserved.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#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 "inode.h"
#include "log.h"
#include "lops.h"
#include "meta_io.h"
#include "trans.h"
#include "util.h"
#include "trace_gfs2.h"
static void gfs2_print_trans(struct gfs2_sbd *sdp, const struct gfs2_trans *tr)
{
fs_warn(sdp, "Transaction created at: %pSR\n", (void *)tr->tr_ip);
fs_warn(sdp, "blocks=%u revokes=%u reserved=%u touched=%u\n",
tr->tr_blocks, tr->tr_revokes, tr->tr_reserved,
test_bit(TR_TOUCHED, &tr->tr_flags));
fs_warn(sdp, "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);
}
int __gfs2_trans_begin(struct gfs2_trans *tr, struct gfs2_sbd *sdp,
unsigned int blocks, unsigned int revokes,
unsigned long ip)
{
if (current->journal_info) {
gfs2_print_trans(sdp, current->journal_info);
BUG();
}
BUG_ON(blocks == 0 && revokes == 0);
if (!test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags))
return -EROFS;
tr->tr_ip = ip;
tr->tr_blocks = blocks;
tr->tr_revokes = revokes;
tr->tr_reserved = GFS2_LOG_FLUSH_MIN_BLOCKS;
if (blocks) {
/*
* The reserved blocks are either used for data or metadata.
* We can have mixed data and metadata, each with its own log
* descriptor block; see calc_reserved().
*/
tr->tr_reserved += blocks + 1 + DIV_ROUND_UP(blocks - 1, databuf_limit(sdp));
}
if (revokes)
tr->tr_reserved += gfs2_struct2blk(sdp, revokes) - 1;
INIT_LIST_HEAD(&tr->tr_databuf);
INIT_LIST_HEAD(&tr->tr_buf);
INIT_LIST_HEAD(&tr->tr_list);
INIT_LIST_HEAD(&tr->tr_ail1_list);
INIT_LIST_HEAD(&tr->tr_ail2_list);
if (gfs2_assert_warn(sdp, tr->tr_reserved <= sdp->sd_jdesc->jd_blocks))
return -EINVAL;
sb_start_intwrite(sdp->sd_vfs);
gfs2_log_reserve(sdp, tr->tr_reserved);
down_read(&sdp->sd_log_flush_lock);
if (unlikely(!test_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags))) {
up_read(&sdp->sd_log_flush_lock);
gfs2_log_release(sdp, tr->tr_reserved);
sb_end_intwrite(sdp->sd_vfs);
return -EROFS;
}
current->journal_info = tr;
return 0;
}
int gfs2_trans_begin(struct gfs2_sbd *sdp, unsigned int blocks,
unsigned int revokes)
{
struct gfs2_trans *tr;
int error;
tr = kmem_cache_zalloc(gfs2_trans_cachep, GFP_NOFS);
if (!tr)
return -ENOMEM;
error = __gfs2_trans_begin(tr, sdp, blocks, revokes, _RET_IP_);
if (error)
kmem_cache_free(gfs2_trans_cachep, tr);
return error;
}
void gfs2_trans_end(struct gfs2_sbd *sdp)
{
struct gfs2_trans *tr = current->journal_info;
s64 nbuf;
current->journal_info = NULL;
if (!test_bit(TR_TOUCHED, &tr->tr_flags)) {
gfs2_log_release(sdp, tr->tr_reserved);
up_read(&sdp->sd_log_flush_lock);
if (!test_bit(TR_ONSTACK, &tr->tr_flags))
gfs2_trans_free(sdp, 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) ||
gfs2_assert_withdraw(sdp, tr->tr_num_revoke <= tr->tr_revokes))
gfs2_print_trans(sdp, tr);
gfs2_log_commit(sdp, tr);
if (!test_bit(TR_ONSTACK, &tr->tr_flags) &&
!test_bit(TR_ATTACHED, &tr->tr_flags))
gfs2_trans_free(sdp, tr);
up_read(&sdp->sd_log_flush_lock);
if (sdp->sd_vfs->s_flags & SB_SYNCHRONOUS)
gfs2_log_flush(sdp, NULL, GFS2_LOG_HEAD_FLUSH_NORMAL |
GFS2_LFC_TRANS_END);
sb_end_intwrite(sdp->sd_vfs);
}
static struct gfs2_bufdata *gfs2_alloc_bufdata(struct gfs2_glock *gl,
struct buffer_head *bh)
{
struct gfs2_bufdata *bd;
bd = kmem_cache_zalloc(gfs2_bufdata_cachep, GFP_NOFS | __GFP_NOFAIL);
bd->bd_bh = bh;
bd->bd_gl = gl;
INIT_LIST_HEAD(&bd->bd_list);
bh->b_private = bd;
return bd;
}
/**
* gfs2_trans_add_data - Add a databuf to the transaction.
* @gl: The inode glock associated with the buffer
* @bh: The buffer to add
*
* This is used in journaled data mode.
* We need to journal the data block in the same way as metadata in
* the functions above. The difference is that here we have a tag
* which is two __be64's being the block number (as per meta data)
* and a flag which says whether the data block needs escaping or
* not. This means we need a new log entry for each 251 or so data
* blocks, which isn't an enormous overhead but twice as much as
* for normal metadata blocks.
*/
void gfs2_trans_add_data(struct gfs2_glock *gl, struct buffer_head *bh)
{
struct gfs2_trans *tr = current->journal_info;
struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
struct gfs2_bufdata *bd;
lock_buffer(bh);
if (buffer_pinned(bh)) {
set_bit(TR_TOUCHED, &tr->tr_flags);
goto out;
}
gfs2_log_lock(sdp);
bd = bh->b_private;
if (bd == NULL) {
gfs2_log_unlock(sdp);
unlock_buffer(bh);
if (bh->b_private == NULL)
bd = gfs2_alloc_bufdata(gl, bh);
else
bd = bh->b_private;
lock_buffer(bh);
gfs2_log_lock(sdp);
}
gfs2_assert(sdp, bd->bd_gl == gl);
set_bit(TR_TOUCHED, &tr->tr_flags);
if (list_empty(&bd->bd_list)) {
set_bit(GLF_LFLUSH, &bd->bd_gl->gl_flags);
set_bit(GLF_DIRTY, &bd->bd_gl->gl_flags);
gfs2_pin(sdp, bd->bd_bh);
tr->tr_num_databuf_new++;
list_add_tail(&bd->bd_list, &tr->tr_databuf);
}
gfs2_log_unlock(sdp);
out:
unlock_buffer(bh);
}
void gfs2_trans_add_meta(struct gfs2_glock *gl, struct buffer_head *bh)
{
struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
struct gfs2_bufdata *bd;
struct gfs2_meta_header *mh;
struct gfs2_trans *tr = current->journal_info;
enum gfs2_freeze_state state = atomic_read(&sdp->sd_freeze_state);
lock_buffer(bh);
if (buffer_pinned(bh)) {
set_bit(TR_TOUCHED, &tr->tr_flags);
goto out;
}
gfs2_log_lock(sdp);
bd = bh->b_private;
if (bd == NULL) {
gfs2_log_unlock(sdp);
unlock_buffer(bh);
lock_page(bh->b_page);
if (bh->b_private == NULL)
bd = gfs2_alloc_bufdata(gl, bh);
else
bd = bh->b_private;
unlock_page(bh->b_page);
lock_buffer(bh);
gfs2_log_lock(sdp);
}
gfs2_assert(sdp, bd->bd_gl == gl);
set_bit(TR_TOUCHED, &tr->tr_flags);
if (!list_empty(&bd->bd_list))
goto out_unlock;
set_bit(GLF_LFLUSH, &bd->bd_gl->gl_flags);
set_bit(GLF_DIRTY, &bd->bd_gl->gl_flags);
mh = (struct gfs2_meta_header *)bd->bd_bh->b_data;
if (unlikely(mh->mh_magic != cpu_to_be32(GFS2_MAGIC))) {
fs_err(sdp, "Attempting to add uninitialised block to "
"journal (inplace block=%lld)\n",
(unsigned long long)bd->bd_bh->b_blocknr);
BUG();
}
if (unlikely(state == SFS_FROZEN)) {
fs_info(sdp, "GFS2:adding buf while frozen\n");
gfs2_assert_withdraw(sdp, 0);
}
if (unlikely(gfs2_withdrawn(sdp))) {
fs_info(sdp, "GFS2:adding buf while withdrawn! 0x%llx\n",
(unsigned long long)bd->bd_bh->b_blocknr);
}
gfs2_pin(sdp, bd->bd_bh);
mh->__pad0 = cpu_to_be64(0);
mh->mh_jid = cpu_to_be32(sdp->sd_jdesc->jd_jid);
list_add(&bd->bd_list, &tr->tr_buf);
tr->tr_num_buf_new++;
out_unlock:
gfs2_log_unlock(sdp);
out:
unlock_buffer(bh);
}
void gfs2_trans_add_revoke(struct gfs2_sbd *sdp, struct gfs2_bufdata *bd)
{
struct gfs2_trans *tr = current->journal_info;
BUG_ON(!list_empty(&bd->bd_list));
gfs2_add_revoke(sdp, bd);
set_bit(TR_TOUCHED, &tr->tr_flags);
tr->tr_num_revoke++;
}
void gfs2_trans_remove_revoke(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_revokes, 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--;
if (bd->bd_gl)
gfs2_glock_remove_revoke(bd->bd_gl);
kmem_cache_free(gfs2_bufdata_cachep, bd);
tr->tr_num_revoke_rm++;
if (--n == 0)
break;
}
}
gfs2_log_unlock(sdp);
}
void gfs2_trans_free(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
{
if (tr == NULL)
return;
gfs2_assert_warn(sdp, list_empty(&tr->tr_ail1_list));
gfs2_assert_warn(sdp, list_empty(&tr->tr_ail2_list));
gfs2_assert_warn(sdp, list_empty(&tr->tr_databuf));
gfs2_assert_warn(sdp, list_empty(&tr->tr_buf));
kmem_cache_free(gfs2_trans_cachep, tr);
}
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