summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorHarshad Shirwadkar <harshadshirwadkar@gmail.com>2020-11-05 19:58:57 -0800
committerTheodore Ts'o <tytso@mit.edu>2020-11-06 23:01:03 -0500
commitc460e5edc85a063ec9cb60addff93d00ed378701 (patch)
treea779fd93ebec507ce8c177c781ce2c7cde1716e2
parent37e0a30e94f1aa25f16b403dfabb64e0b806de0b (diff)
downloadlinux-stable-c460e5edc85a063ec9cb60addff93d00ed378701.tar.gz
linux-stable-c460e5edc85a063ec9cb60addff93d00ed378701.tar.bz2
linux-stable-c460e5edc85a063ec9cb60addff93d00ed378701.zip
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 <jack@suse.cz> Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com> Link: https://lore.kernel.org/r/20201106035911.1942128-9-harshadshirwadkar@gmail.com Signed-off-by: Theodore Ts'o <tytso@mit.edu>
-rw-r--r--fs/jbd2/journal.c6
-rw-r--r--include/linux/jbd2.h10
2 files changed, 6 insertions, 10 deletions
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 500152f0421a..778ea50fc8d1 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 b2caf7bbd8e5..5f0ef6380b0c 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;