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Date: Fri, 9 Aug 2019 14:57:43 -0600
From: Andreas Dilger <adilger@...ger.ca>
To: Harshad Shirwadkar <harshadshirwadkar@...il.com>
Cc: linux-ext4@...r.kernel.org
Subject: Re: [PATCH v2 06/12] jbd2: fast-commit recovery path changes
> On Aug 8, 2019, at 9:45 PM, Harshad Shirwadkar <harshadshirwadkar@...il.com> wrote:
>
> This patch adds fast-commit recovery path changes for JBD2. If we find
> a fast commit block that is valid in our recovery phase call file
> system specific routine to handle that block.
>
> We also clear the fast commit flag in jbd2_mark_journal_empty() which
> is called after successful recovery as well successful
... as well as after successful ...
> checkpointing. This allows JBD2 journal to be compatible with older
> versions when there are not fast commit blocks.
>
> Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@...il.com>
Reviewed-by: Andreas Dilger <adilger@...ger.ca>
>
> ---
>
> Changelog:
>
> V2: Fixed checkpatch error.
> ---
> fs/jbd2/journal.c | 12 ++++++++++
> fs/jbd2/recovery.c | 59 +++++++++++++++++++++++++++++++++++++++++++---
> 2 files changed, 68 insertions(+), 3 deletions(-)
>
> diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
> index 1e15804b2c3c..ae4584a60cc3 100644
> --- a/fs/jbd2/journal.c
> +++ b/fs/jbd2/journal.c
> @@ -1604,6 +1604,7 @@ int jbd2_journal_update_sb_log_tail(journal_t *journal, tid_t tail_tid,
> static void jbd2_mark_journal_empty(journal_t *journal, int write_op)
> {
> journal_superblock_t *sb = journal->j_superblock;
> + bool had_fast_commit = false;
>
> BUG_ON(!mutex_is_locked(&journal->j_checkpoint_mutex));
> lock_buffer(journal->j_sb_buffer);
> @@ -1617,6 +1618,14 @@ static void jbd2_mark_journal_empty(journal_t *journal, int write_op)
>
> sb->s_sequence = cpu_to_be32(journal->j_tail_sequence);
> sb->s_start = cpu_to_be32(0);
> + if (jbd2_has_feature_fast_commit(journal)) {
> + /*
> + * When journal is clean, no need to commit fast commit flag and
> + * make file system incompatible with older kernels.
> + */
> + jbd2_clear_feature_fast_commit(journal);
> + had_fast_commit = true;
> + }
>
> jbd2_write_superblock(journal, write_op);
>
> @@ -1624,6 +1633,9 @@ static void jbd2_mark_journal_empty(journal_t *journal, int write_op)
> write_lock(&journal->j_state_lock);
> journal->j_flags |= JBD2_FLUSHED;
> write_unlock(&journal->j_state_lock);
> +
> + if (had_fast_commit)
> + jbd2_set_feature_fast_commit(journal);
> }
>
>
> diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
> index a4967b27ffb6..3a6cd1497504 100644
> --- a/fs/jbd2/recovery.c
> +++ b/fs/jbd2/recovery.c
> @@ -225,8 +225,12 @@ 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_last_fc : (journal)->j_last; \
> + \
> + if (var >= _wrap_last) \
> + var -= (_wrap_last - (journal)->j_first); \
> } while (0)
>
> /**
> @@ -413,6 +417,49 @@ static int jbd2_block_tag_csum_verify(journal_t *j, journal_block_tag_t *tag,
> return tag->t_checksum == cpu_to_be16(csum32);
> }
>
> +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;
> + unsigned int seq;
> + journal_header_t *jhdr;
> + int err = 0;
> +
> + next_fc_block = journal->j_first_fc;
> +
> + while (next_fc_block != journal->j_last_fc) {
> + jbd_debug(3, "Fast commit replay: next block %lld",
> + next_fc_block);
> + err = jread(&bh, journal, next_fc_block);
> + if (err)
> + break;
> +
> + jhdr = (journal_header_t *)bh->b_data;
> + seq = be32_to_cpu(jhdr->h_sequence);
> + if (be32_to_cpu(jhdr->h_magic) != JBD2_MAGIC_NUMBER ||
> + seq != expected_commit_id) {
> + break;
> + }
> + jbd_debug(3, "Processing fast commit blk with seq %d",
> + seq);
> + if (pass == PASS_REPLAY &&
> + journal->j_fc_replay_callback) {
> + err = journal->j_fc_replay_callback(journal,
> + bh);
> + if (err)
> + break;
> + }
> + next_fc_block++;
> + }
> +
> + if (err)
> + jbd_debug(3, "Fast commit replay failed, err = %d\n", err);
> +
> + return err;
> +}
> +
> static int do_one_pass(journal_t *journal,
> struct recovery_info *info, enum passtype pass)
> {
> @@ -470,7 +517,7 @@ 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, journal->j_last_fc);
>
> /* Skip over each chunk of the transaction looking
> * either the next descriptor block or the final commit
> @@ -768,6 +815,8 @@ static int do_one_pass(journal_t *journal,
> if (err)
> goto failed;
> continue;
> + case JBD2_FC_BLOCK:
> + continue;
>
> default:
> jbd_debug(3, "Unrecognised magic %d, end of scan.\n",
> @@ -799,6 +848,10 @@ static int do_one_pass(journal_t *journal,
> success = -EIO;
> }
> }
> +
> + if (jbd2_has_feature_fast_commit(journal) && pass == PASS_REPLAY)
> + fc_do_one_pass(journal, info, pass);
> +
> if (block_error && success == 0)
> success = -EIO;
> return success;
> --
> 2.23.0.rc1.153.gdeed80330f-goog
>
Cheers, Andreas
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