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