Commit 5b849b5f authored by Harshad Shirwadkar's avatar Harshad Shirwadkar Committed by Theodore Ts'o
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jbd2: fast commit recovery path 



This patch adds fast commit recovery support in JBD2.

Signed-off-by: default avatarHarshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://lore.kernel.org/r/20201015203802.3597742-7-harshadshirwadkar@gmail.com


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent aa75f4d3

fs/ext4/fast_commit.c

+15 −0
Original line number Diff line number Diff line
@@ -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;

fs/jbd2/recovery.c

+53 −4
Original line number Diff line number Diff line
@@ -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;

include/linux/jbd2.h

+20 −0
Original line number Diff line number Diff line
@@ -751,6 +751,11 @@ jbd2_time_diff(unsigned long start, unsigned long end) 


#define JBD2_NR_BATCH	64



enum passtype {PASS_SCAN, PASS_REVOKE, PASS_REPLAY};



#define JBD2_FC_REPLAY_STOP	0

#define JBD2_FC_REPLAY_CONTINUE	1



/**

 * struct journal_s - The journal_s type is the concrete type associated with

 *     journal_t.
@@ -1248,6 +1253,21 @@ struct journal_s 
	 */

	void (*j_fc_cleanup_callback)(struct journal_s *journal, int);



	/*

	 * @j_fc_replay_callback:

	 *

	 * File-system specific function that performs replay of a fast

	 * commit. JBD2 calls this function for each fast commit block found in

	 * the journal. This function should return JBD2_FC_REPLAY_CONTINUE

	 * to indicate that the block was processed correctly and more fast

	 * commit replay should continue. Return value of JBD2_FC_REPLAY_STOP

	 * indicates the end of replay (no more blocks remaining). A negative

	 * return value indicates error.

	 */

	int (*j_fc_replay_callback)(struct journal_s *journal,

				    struct buffer_head *bh,

				    enum passtype pass, int off,

				    tid_t expected_commit_id);

};



#define jbd2_might_wait_for_commit(j) \