From 5b849b5f96b47d82b5a432d8b91a8ad260e1de46 Mon Sep 17 00:00:00 2001
From: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Date: Thu, 15 Oct 2020 13:37:58 -0700
Subject: jbd2: fast commit recovery path

This patch adds fast commit recovery support in JBD2.

Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://lore.kernel.org/r/20201015203802.3597742-7-harshadshirwadkar@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 fs/ext4/fast_commit.c | 15 ++++++++++++++
 fs/jbd2/recovery.c    | 57 +++++++++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 68 insertions(+), 4 deletions(-)

(limited to 'fs')

diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c
index 79e947c43198..888d9d217d5b 100644
--- a/fs/ext4/fast_commit.c
+++ b/fs/ext4/fast_commit.c
@@ -1188,8 +1188,23 @@ static void ext4_fc_cleanup(journal_t *journal, int full)
 	trace_ext4_fc_stats(sb);
 }
 
+/*
+ * Main recovery path entry point.
+ */
+static int ext4_fc_replay(journal_t *journal, struct buffer_head *bh,
+				enum passtype pass, int off, tid_t expected_tid)
+{
+	return 0;
+}
+
 void ext4_fc_init(struct super_block *sb, journal_t *journal)
 {
+	/*
+	 * We set replay callback even if fast commit disabled because we may
+	 * could still have fast commit blocks that need to be replayed even if
+	 * fast commit has now been turned off.
+	 */
+	journal->j_fc_replay_callback = ext4_fc_replay;
 	if (!test_opt2(sb, JOURNAL_FAST_COMMIT))
 		return;
 	journal->j_fc_cleanup_callback = ext4_fc_cleanup;
diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
index fb134c7a12c8..eb2606133cd8 100644
--- a/fs/jbd2/recovery.c
+++ b/fs/jbd2/recovery.c
@@ -35,7 +35,6 @@ struct recovery_info
 	int		nr_revoke_hits;
 };
 
-enum passtype {PASS_SCAN, PASS_REVOKE, PASS_REPLAY};
 static int do_one_pass(journal_t *journal,
 				struct recovery_info *info, enum passtype pass);
 static int scan_revoke_records(journal_t *, struct buffer_head *,
@@ -225,10 +224,51 @@ static int count_tags(journal_t *journal, struct buffer_head *bh)
 /* Make sure we wrap around the log correctly! */
 #define wrap(journal, var)						\
 do {									\
-	if (var >= (journal)->j_last)					\
-		var -= ((journal)->j_last - (journal)->j_first);	\
+	unsigned long _wrap_last =					\
+		jbd2_has_feature_fast_commit(journal) ?			\
+			(journal)->j_fc_last : (journal)->j_last;	\
+									\
+	if (var >= _wrap_last)						\
+		var -= (_wrap_last - (journal)->j_first);		\
 } while (0)
 
+static int fc_do_one_pass(journal_t *journal,
+			  struct recovery_info *info, enum passtype pass)
+{
+	unsigned int expected_commit_id = info->end_transaction;
+	unsigned long next_fc_block;
+	struct buffer_head *bh;
+	int err = 0;
+
+	next_fc_block = journal->j_fc_first;
+	if (!journal->j_fc_replay_callback)
+		return 0;
+
+	while (next_fc_block <= journal->j_fc_last) {
+		jbd_debug(3, "Fast commit replay: next block %ld",
+			  next_fc_block);
+		err = jread(&bh, journal, next_fc_block);
+		if (err) {
+			jbd_debug(3, "Fast commit replay: read error");
+			break;
+		}
+
+		jbd_debug(3, "Processing fast commit blk with seq %d");
+		err = journal->j_fc_replay_callback(journal, bh, pass,
+					next_fc_block - journal->j_fc_first,
+					expected_commit_id);
+		next_fc_block++;
+		if (err < 0 || err == JBD2_FC_REPLAY_STOP)
+			break;
+		err = 0;
+	}
+
+	if (err)
+		jbd_debug(3, "Fast commit replay failed, err = %d\n", err);
+
+	return err;
+}
+
 /**
  * jbd2_journal_recover - recovers a on-disk journal
  * @journal: the journal to recover
@@ -472,7 +512,9 @@ static int do_one_pass(journal_t *journal,
 				break;
 
 		jbd_debug(2, "Scanning for sequence ID %u at %lu/%lu\n",
-			  next_commit_ID, next_log_block, journal->j_last);
+			  next_commit_ID, next_log_block,
+			  jbd2_has_feature_fast_commit(journal) ?
+			  journal->j_fc_last : journal->j_last);
 
 		/* Skip over each chunk of the transaction looking
 		 * either the next descriptor block or the final commit
@@ -834,6 +876,13 @@ static int do_one_pass(journal_t *journal,
 				success = -EIO;
 		}
 	}
+
+	if (jbd2_has_feature_fast_commit(journal) &&  pass != PASS_REVOKE) {
+		err = fc_do_one_pass(journal, info, pass);
+		if (err)
+			success = err;
+	}
+
 	if (block_error && success == 0)
 		success = -EIO;
 	return success;
-- 
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