/*
* linux/fs/jbd2/commit.c
*
* Written by Stephen C. Tweedie <sct@redhat.com>, 1998
*
* Copyright 1998 Red Hat corp --- All Rights Reserved
*
* This file is part of the Linux kernel and is made available under
* the terms of the GNU General Public License, version 2, or at your
* option, any later version, incorporated herein by reference.
*
* Journal commit routines for the generic filesystem journaling code;
* part of the ext2fs journaling system.
*/
#include <linux/time.h>
#include <linux/fs.h>
#include <linux/jbd2.h>
#include <linux/marker.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/jiffies.h>
#include <linux/crc32.h>
#include <linux/writeback.h>
#include <linux/backing-dev.h>
#include <linux/bio.h>
/*
* Default IO end handler for temporary BJ_IO buffer_heads.
*/
static void journal_end_buffer_io_sync(struct buffer_head *bh, int uptodate)
{
BUFFER_TRACE(bh, "");
if (uptodate)
set_buffer_uptodate(bh);
else
clear_buffer_uptodate(bh);
unlock_buffer(bh);
}
/*
* When an ext4 file is truncated, it is possible that some pages are not
* successfully freed, because they are attached to a committing transaction.
* After the transaction commits, these pages are left on the LRU, with no
* ->mapping, and with attached buffers. These pages are trivially reclaimable
* by the VM, but their apparent absence upsets the VM accounting, and it makes
* the numbers in /proc/meminfo look odd.
*
* So here, we have a buffer which has just come off the forget list. Look to
* see if we can strip all buffers from the backing page.
*
* Called under lock_journal(), and possibly under journal_datalist_lock. The
* caller provided us with a ref against the buffer, and we drop that here.
*/
static void release_buffer_page(struct buffer_head *bh)
{
struct page *page;
if (buffer_dirty(bh))
goto nope;
if (atomic_read(&bh->b_count) != 1)
goto nope;
page = bh->b_page;
if (!page)
goto nope;
if (page->mapping)
goto nope;
/* OK, it's a truncated page */
if (!trylock_page(page))
goto nope;
page_cache_get(page);
__brelse(bh);
try_to_free_buffers(page);
unlock_page(page);
page_cache_release(page);
return;
nope:
__brelse(bh);
}
/*
* Done it all: now submit the commit record. We should have
* cleaned up our previous buffers by now, so if we are in abort
* mode we can now just skip the rest of the journal write
* entirely.
*
* Returns 1 if the journal needs to be aborted or 0 on success
*/
static int journal_submit_commit_record(journal_t *journal,
transaction_t *commit_transaction,
struct buffer_head **cbh,
__u32 crc32_sum)
{
struct journal_head *descriptor;
struct commit_header *tmp;
struct buffer_head *bh;
int ret;
int barrier_done = 0;
struct timespec now = current_kernel_time();
if (is_journal_aborted(journal))
return 0;
descriptor = jbd2_journal_get_descriptor_buffer(journal);
if (!descriptor)
return 1;
bh = jh2bh(descriptor);
tmp = (struct commit_header *)bh->b_data;
tmp->h_magic = cpu_to_be32(JBD2_MAGIC_NUMBER);
tmp->h_blocktype = cpu_to_be32(JBD2_COMMIT_BLOCK);
tmp->h_sequence = cpu_to_be32(commit_transaction->t_tid);
tmp->h_commit_sec = cpu_to_be64(now.tv_sec);
tmp->h_commit_nsec = cpu_to_be32(now.tv_nsec);
if (JBD2_HAS_COMPAT_FEATURE(journal,
JBD2_FEATURE_COMPAT_CHECKSUM)) {
tmp->h_chksum_type = JBD2_CRC32_CHKSUM;
tmp->h_chksum_size = JBD2_CRC32_CHKSUM_SIZE;
tmp->h_chksum[0] = cpu_to_be32(crc32_sum);
}
JBUFFER_TRACE(descriptor, "submit commit block");
lock_buffer(bh);
clear_buffer_dirty(bh);
set_buffer_uptodate(bh);
bh->b_end_io = journal_end_buffer_io_sync;
if (journal->j_flags & JBD2_BARRIER &&
!JBD2_HAS_INCOMPAT_FEATURE(journal,
JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
set_buffer_ordered(bh);
barrier_done = 1;
}
ret = submit_bh(WRITE_SYNC_PLUG, bh);
if (barrier_done)
clear_buffer_ordered(bh);
/* is it possible for another commit to fail at roughly
* the same time as this one? If so, we don't want to
* trust the barrier flag in the super, but instead want
* to remember if we sent a barrier request
*/
if (ret == -EOPNOTSUPP && barrier_done) {
printk(KERN_WARNING
"JBD: barrier-based sync failed on %s - "
"disabling barriers\n", journal->j_devname);
spin_lock(&journal->j_state_lock);
journal->j_flags &= ~JBD2_BARRIER;
spin_unlock(&journal->j_state_lock);
/* And try again, without the barrier */
lock_buffer(bh);
set_buffer_uptodate(bh);