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[PATCH] Fix reiserfs latencies caused by data=ordered

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ReiserFS does periodic cleanup of old transactions in order to limit the
length of time a journal replay may take after a crash.  Sometimes, writing
metadata from an old (already committed) transaction may require committing
a newer transaction, which also requires writing all data=ordered buffers.
This can cause very long stalls on journal_begin.

This patch makes sure new transactions will not need to be committed before
trying a periodic reclaim of an old transaction.  It is low risk because if
a bad decision is made, it just means a slightly longer journal replay
after a crash.

Signed-off-by: Chris Mason <mason@suse.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Chris Mason 2006-09-29 01:59:56 -07:00 • committed by Linus Torvalds
commit a317202714
1 changed files with 43 additions and 11 deletions
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54
fs/reiserfs/journal.c
View file

@ -1186,6 +1186,21 @@ static struct reiserfs_journal_list *find_newer_jl_for_cn(struct
return NULL;
}
static int newer_jl_done(struct reiserfs_journal_cnode *cn)
{
struct super_block *sb = cn->sb;
b_blocknr_t blocknr = cn->blocknr;
cn = cn->hprev;
while (cn) {
if (cn->sb == sb && cn->blocknr == blocknr && cn->jlist &&
atomic_read(&cn->jlist->j_commit_left) != 0)
return 0;
cn = cn->hprev;
}
return 1;
}
static void remove_journal_hash(struct super_block *,
struct reiserfs_journal_cnode **,
struct reiserfs_journal_list *, unsigned long,
@ -1604,6 +1619,31 @@ static int flush_journal_list(struct super_block *s,
return err;
}
static int test_transaction(struct super_block *s,
struct reiserfs_journal_list *jl)
{
struct reiserfs_journal_cnode *cn;
if (jl->j_len == 0 || atomic_read(&jl->j_nonzerolen) == 0)
return 1;
cn = jl->j_realblock;
while (cn) {
/* if the blocknr == 0, this has been cleared from the hash,
** skip it
*/
if (cn->blocknr == 0) {
goto next;
}
if (cn->bh && !newer_jl_done(cn))
return 0;
next:
cn = cn->next;
cond_resched();
}
return 0;
}
static int write_one_transaction(struct super_block *s,
struct reiserfs_journal_list *jl,
struct buffer_chunk *chunk)
@ -3433,16 +3473,6 @@ static void flush_async_commits(void *p)
flush_commit_list(p_s_sb, jl, 1);
}
unlock_kernel();
/*
* this is a little racey, but there's no harm in missing
* the filemap_fdata_write
*/
if (!atomic_read(&journal->j_async_throttle)
&& !reiserfs_is_journal_aborted(journal)) {
atomic_inc(&journal->j_async_throttle);
filemap_fdatawrite(p_s_sb->s_bdev->bd_inode->i_mapping);
atomic_dec(&journal->j_async_throttle);
}
}
/*
@ -3844,7 +3874,9 @@ static void flush_old_journal_lists(struct super_block *s)
entry = journal->j_journal_list.next;
jl = JOURNAL_LIST_ENTRY(entry);
/* this check should always be run, to send old lists to disk */
if (jl->j_timestamp < (now - (JOURNAL_MAX_TRANS_AGE * 4))) {
if (jl->j_timestamp < (now - (JOURNAL_MAX_TRANS_AGE * 4)) &&
atomic_read(&jl->j_commit_left) == 0 &&
test_transaction(s, jl)) {
flush_used_journal_lists(s, jl);
} else {
break;