Linux-ext4 Archive on lore.kernel.org
 help / color / Atom feed
From: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
To: linux-ext4@vger.kernel.org
Cc: tytso@mit.edu, Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Subject: [PATCH v7 4/7] jbd2: add fast commit machinery
Date: Tue, 21 Jul 2020 08:54:52 -0700
Message-ID: <20200721155455.1364597-5-harshadshirwadkar@gmail.com> (raw)
In-Reply-To: <20200721155455.1364597-1-harshadshirwadkar@gmail.com>

This patch implements following APIs in JBD2 to allow for fast
commits:

jbd2_fc_start(): Start a new fast commit. This function waits for any
existing fast commit or full commit to complete.

jbd2_fc_stop(): Stop fast commit. This function ends current fast
commit and wakes up either the journal thread or the other fast commit
waiting for current fast commit to complete.

jbd2_fc_stop_do_commit(): Stop fast commit and perform a full
commit. This is same as above but also performs a full commit.

This patch also adds a cleanup handler in journal_t that is called
after every full and fast commit.

Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
---
 fs/ext4/fast_commit.c |  8 ++++++
 fs/jbd2/commit.c      | 19 ++++++++++++
 fs/jbd2/journal.c     | 67 +++++++++++++++++++++++++++++++++++++++++++
 include/linux/jbd2.h  | 21 ++++++++++++++
 4 files changed, 115 insertions(+)

diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c
index 0dad8bdb1253..f2d11b4c6b62 100644
--- a/fs/ext4/fast_commit.c
+++ b/fs/ext4/fast_commit.c
@@ -8,11 +8,19 @@
  * Ext4 fast commits routines.
  */
 #include "ext4_jbd2.h"
+/*
+ * Fast commit cleanup routine. This is called after every fast commit and
+ * full commit. full is true if we are called after a full commit.
+ */
+static void ext4_fc_cleanup(journal_t *journal, int full)
+{
+}
 
 void ext4_fc_init(struct super_block *sb, journal_t *journal)
 {
 	if (!test_opt2(sb, JOURNAL_FAST_COMMIT))
 		return;
+	journal->j_fc_cleanup_callback = ext4_fc_cleanup;
 	if (jbd2_fc_init(journal, EXT4_NUM_FC_BLKS)) {
 		pr_warn("Error while enabling fast commits, turning off.");
 		ext4_clear_feature_fast_commit(sb);
diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index e855d8260433..e03f5183aae1 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -413,6 +413,20 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 	J_ASSERT(journal->j_running_transaction != NULL);
 	J_ASSERT(journal->j_committing_transaction == NULL);
 
+	write_lock(&journal->j_state_lock);
+	journal->j_flags |= JBD2_FULL_COMMIT_ONGOING;
+	while (journal->j_flags & JBD2_FAST_COMMIT_ONGOING) {
+		DEFINE_WAIT(wait);
+
+		prepare_to_wait(&journal->j_wait_fc, &wait,
+				TASK_UNINTERRUPTIBLE);
+		write_unlock(&journal->j_state_lock);
+		schedule();
+		write_lock(&journal->j_state_lock);
+		finish_wait(&journal->j_wait_fc, &wait);
+	}
+	write_unlock(&journal->j_state_lock);
+
 	commit_transaction = journal->j_running_transaction;
 
 	trace_jbd2_start_commit(journal, commit_transaction);
@@ -1119,12 +1133,16 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 
 	if (journal->j_commit_callback)
 		journal->j_commit_callback(journal, commit_transaction);
+	if (journal->j_fc_cleanup_callback)
+		journal->j_fc_cleanup_callback(journal, 1);
 
 	trace_jbd2_end_commit(journal, commit_transaction);
 	jbd_debug(1, "JBD2: commit %d complete, head %d\n",
 		  journal->j_commit_sequence, journal->j_tail_sequence);
 
 	write_lock(&journal->j_state_lock);
+	journal->j_flags &= ~JBD2_FULL_COMMIT_ONGOING;
+	journal->j_flags &= ~JBD2_FAST_COMMIT_ONGOING;
 	spin_lock(&journal->j_list_lock);
 	commit_transaction->t_state = T_FINISHED;
 	/* Check if the transaction can be dropped now that we are finished */
@@ -1136,6 +1154,7 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 	spin_unlock(&journal->j_list_lock);
 	write_unlock(&journal->j_state_lock);
 	wake_up(&journal->j_wait_done_commit);
+	wake_up(&journal->j_wait_fc);
 
 	/*
 	 * Calculate overall stats
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 494de5410076..0c068d66de7a 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -714,6 +714,72 @@ int jbd2_log_wait_commit(journal_t *journal, tid_t tid)
 	return err;
 }
 
+/*
+ * Start a fast commit. If there's an ongoing fast or full commit wait for
+ * it to complete. Returns 0 if a new fast commit was started. Returns -EALREADY
+ * if a fast commit is not needed, either because there's an already a commit
+ * going on or this tid has already been committed. Returns -EINVAL if no jbd2
+ * commit has yet been performed.
+ */
+int jbd2_fc_start(journal_t *journal, tid_t tid)
+{
+	/*
+	 * Fast commits only allowed if at least one full commit has
+	 * been processed.
+	 */
+	if (!journal->j_stats.ts_tid)
+		return -EINVAL;
+
+	if (tid <= journal->j_commit_sequence)
+		return -EALREADY;
+
+	write_lock(&journal->j_state_lock);
+	if (journal->j_flags & JBD2_FULL_COMMIT_ONGOING ||
+	    (journal->j_flags & JBD2_FAST_COMMIT_ONGOING)) {
+		DEFINE_WAIT(wait);
+
+		prepare_to_wait(&journal->j_wait_fc, &wait,
+				TASK_UNINTERRUPTIBLE);
+		write_unlock(&journal->j_state_lock);
+		schedule();
+		finish_wait(&journal->j_wait_fc, &wait);
+		return -EALREADY;
+	}
+	journal->j_flags |= JBD2_FAST_COMMIT_ONGOING;
+	write_unlock(&journal->j_state_lock);
+
+	return 0;
+}
+
+/*
+ * Stop a fast commit. If fallback is set, this function starts commit of
+ * TID tid before any other fast commit can start.
+ */
+static int __jbd2_fc_stop(journal_t *journal, tid_t tid, bool fallback)
+{
+	if (journal->j_fc_cleanup_callback)
+		journal->j_fc_cleanup_callback(journal, 0);
+	write_lock(&journal->j_state_lock);
+	journal->j_flags &= ~JBD2_FAST_COMMIT_ONGOING;
+	if (fallback)
+		journal->j_flags |= JBD2_FULL_COMMIT_ONGOING;
+	write_unlock(&journal->j_state_lock);
+	wake_up(&journal->j_wait_fc);
+	if (fallback)
+		return jbd2_complete_transaction(journal, tid);
+	return 0;
+}
+
+int jbd2_fc_stop(journal_t *journal)
+{
+	return __jbd2_fc_stop(journal, 0, 0);
+}
+
+int jbd2_fc_stop_do_commit(journal_t *journal, tid_t tid)
+{
+	return __jbd2_fc_stop(journal, tid, 1);
+}
+
 /* Return 1 when transaction with given tid has already committed. */
 int jbd2_transaction_committed(journal_t *journal, tid_t tid)
 {
@@ -1140,6 +1206,7 @@ static journal_t *journal_init_common(struct block_device *bdev,
 	init_waitqueue_head(&journal->j_wait_commit);
 	init_waitqueue_head(&journal->j_wait_updates);
 	init_waitqueue_head(&journal->j_wait_reserved);
+	init_waitqueue_head(&journal->j_wait_fc);
 	mutex_init(&journal->j_barrier);
 	mutex_init(&journal->j_checkpoint_mutex);
 	spin_lock_init(&journal->j_revoke_lock);
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 65b7107dcaa0..965e09d8819a 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -853,6 +853,13 @@ struct journal_s
 	 */
 	wait_queue_head_t	j_wait_reserved;
 
+	/**
+	 * @j_wait_fc:
+	 *
+	 * Wait queue to wait for completion of async fast commits.
+	 */
+	wait_queue_head_t	j_wait_fc;
+
 	/**
 	 * @j_checkpoint_mutex:
 	 *
@@ -1203,6 +1210,15 @@ struct journal_s
 	 */
 	struct lockdep_map	j_trans_commit_map;
 #endif
+
+	/**
+	 * @j_fc_cleanup_callback:
+	 *
+	 * Clean-up after fast commit or full commit. JBD2 calls this function
+	 * after every commit operation.
+	 */
+	void (*j_fc_cleanup_callback)(struct journal_s *journal, int);
+
 };
 
 #define jbd2_might_wait_for_commit(j) \
@@ -1288,6 +1304,8 @@ JBD2_FEATURE_INCOMPAT_FUNCS(fast_commit,	FAST_COMMIT)
 						 * data write error in ordered
 						 * mode */
 #define JBD2_REC_ERR	0x080	/* The errno in the sb has been recorded */
+#define JBD2_FAST_COMMIT_ONGOING	0x100	/* Fast commit is ongoing */
+#define JBD2_FULL_COMMIT_ONGOING	0x200	/* Full commit is ongoing */
 
 /*
  * Function declarations for the journaling transaction and buffer
@@ -1542,6 +1560,9 @@ extern int jbd2_cleanup_journal_tail(journal_t *);
 
 /* Fast commit related APIs */
 int jbd2_fc_init(journal_t *journal, int num_fc_blks);
+int jbd2_fc_start(journal_t *journal, tid_t tid);
+int jbd2_fc_stop(journal_t *journal);
+int jbd2_fc_stop_do_commit(journal_t *journal, tid_t tid);
 /*
  * is_journal_abort
  *
-- 
2.28.0.rc0.105.gf9edc3c819-goog


  parent reply index

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-21 15:54 [PATCH v7 0/7] ext4: add fast commits feature Harshad Shirwadkar
2020-07-21 15:54 ` [PATCH v7 1/7] doc: update ext4 and journalling docs to include fast commit feature Harshad Shirwadkar
2020-07-21 15:54 ` [PATCH v7 2/7] ext4: add fast_commit feature and handling for extended mount options Harshad Shirwadkar
2020-07-21 15:54 ` [PATCH v7 3/7] ext4 / jbd2: add fast commit initialization Harshad Shirwadkar
2020-07-21 15:54 ` Harshad Shirwadkar [this message]
2020-07-21 15:54 ` [PATCH v7 5/7] ext4: main fast-commit commit path Harshad Shirwadkar
2020-07-21 15:54 ` [PATCH v7 6/7] jbd2: fast commit recovery path Harshad Shirwadkar
2020-07-21 15:54 ` [PATCH v7 7/7] ext4: " Harshad Shirwadkar

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200721155455.1364597-5-harshadshirwadkar@gmail.com \
    --to=harshadshirwadkar@gmail.com \
    --cc=linux-ext4@vger.kernel.org \
    --cc=tytso@mit.edu \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-ext4 Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-ext4/0 linux-ext4/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-ext4 linux-ext4/ https://lore.kernel.org/linux-ext4 \
		linux-ext4@vger.kernel.org
	public-inbox-index linux-ext4

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-ext4


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git