From c460e5edc85a063ec9cb60addff93d00ed378701 Mon Sep 17 00:00:00 2001 From: Harshad Shirwadkar Date: Thu, 5 Nov 2020 19:58:57 -0800 Subject: [PATCH] jbd2: don't use state lock during commit path Variables journal->j_fc_off, journal->j_fc_wbuf are accessed during commit path. Since today we allow only one process to perform a fast commit, there is no need take state lock before accessing these variables. This patch removes these locks and adds comments to describe this. Suggested-by: Jan Kara Signed-off-by: Harshad Shirwadkar Link: https://lore.kernel.org/r/20201106035911.1942128-9-harshadshirwadkar@gmail.com Signed-off-by: Theodore Ts'o --- fs/jbd2/journal.c | 6 ------ include/linux/jbd2.h | 10 ++++++---- 2 files changed, 6 insertions(+), 10 deletions(-) diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c index 500152f0421a5..778ea50fc8d11 100644 --- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -865,7 +865,6 @@ int jbd2_fc_get_buf(journal_t *journal, struct buffer_head **bh_out) int fc_off; *bh_out = NULL; - write_lock(&journal->j_state_lock); if (journal->j_fc_off + journal->j_fc_first < journal->j_fc_last) { fc_off = journal->j_fc_off; @@ -874,7 +873,6 @@ int jbd2_fc_get_buf(journal_t *journal, struct buffer_head **bh_out) } else { ret = -EINVAL; } - write_unlock(&journal->j_state_lock); if (ret) return ret; @@ -909,9 +907,7 @@ int jbd2_fc_wait_bufs(journal_t *journal, int num_blks) struct buffer_head *bh; int i, j_fc_off; - read_lock(&journal->j_state_lock); j_fc_off = journal->j_fc_off; - read_unlock(&journal->j_state_lock); /* * Wait in reverse order to minimize chances of us being woken up before @@ -939,9 +935,7 @@ int jbd2_fc_release_bufs(journal_t *journal) struct buffer_head *bh; int i, j_fc_off; - read_lock(&journal->j_state_lock); j_fc_off = journal->j_fc_off; - read_unlock(&journal->j_state_lock); /* * Wait in reverse order to minimize chances of us being woken up before diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h index b2caf7bbd8e56..5f0ef6380b0c8 100644 --- a/include/linux/jbd2.h +++ b/include/linux/jbd2.h @@ -945,8 +945,9 @@ struct journal_s /** * @j_fc_off: * - * Number of fast commit blocks currently allocated. - * [j_state_lock]. + * Number of fast commit blocks currently allocated. Accessed only + * during fast commit. Currently only process can do fast commit, so + * this field is not protected by any lock. */ unsigned long j_fc_off; @@ -1109,8 +1110,9 @@ struct journal_s struct buffer_head **j_wbuf; /** - * @j_fc_wbuf: Array of fast commit bhs for - * jbd2_journal_commit_transaction. + * @j_fc_wbuf: Array of fast commit bhs for fast commit. Accessed only + * during a fast commit. Currently only process can do fast commit, so + * this field is not protected by any lock. */ struct buffer_head **j_fc_wbuf; -- 2.30.2