This patch allows file systems to turn fast commits on and thereby
restrict the normal journalling space to total journal blocks minus
JBD2_FAST_COMMIT_BLOCKS. Fast commits are not actually performed, just
the interface to turn fast commits on is opened.
Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@xxxxxxxxx>
---
fs/ext4/super.c | 5 +++-
fs/jbd2/journal.c | 68 +++++++++++++++++++++++++++++++++-----------
include/linux/jbd2.h | 39 +++++++++++++++++++++++++
3 files changed, 95 insertions(+), 17 deletions(-)
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index e376ac040cce..7725eb2105f4 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4933,7 +4933,10 @@ static int ext4_load_journal(struct super_block *sb,
if (save)
memcpy(save, ((char *) es) +
EXT4_S_ERR_START, EXT4_S_ERR_LEN);
- err = jbd2_journal_load(journal);
+ if (test_opt2(sb, JOURNAL_FAST_COMMIT))
+ err = jbd2_journal_load_with_fc(journal);
+ else
+ err = jbd2_journal_load(journal);
if (save)
memcpy(((char *) es) + EXT4_S_ERR_START,
save, EXT4_S_ERR_LEN);
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 953990eb70a9..7c13834873ad 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -1159,12 +1159,15 @@ static journal_t *journal_init_common(struct block_device *bdev,
journal->j_blk_offset = start;
journal->j_maxlen = len;
n = journal->j_blocksize / sizeof(journal_block_tag_t);
- journal->j_wbufsize = n;
+ journal->j_wbufsize = n - JBD2_FAST_COMMIT_BLOCKS;
journal->j_wbuf = kmalloc_array(n, sizeof(struct buffer_head *),
GFP_KERNEL);
if (!journal->j_wbuf)
goto err_cleanup;
+ journal->j_fc_wbuf = &journal->j_wbuf[journal->j_wbufsize];
+ journal->j_fc_wbufsize = JBD2_FAST_COMMIT_BLOCKS;
+
bh = getblk_unmovable(journal->j_dev, start, journal->j_blocksize);
if (!bh) {
pr_err("%s: Cannot get buffer for journal superblock\n",
@@ -1297,11 +1300,19 @@ static int journal_reset(journal_t *journal)
}
journal->j_first = first;
- journal->j_last = last;
- journal->j_head = first;
- journal->j_tail = first;
- journal->j_free = last - first;
+ if (jbd2_has_feature_fast_commit(journal)) {
+ journal->j_last_fc = last;
+ journal->j_last = last - JBD2_FAST_COMMIT_BLOCKS;
+ journal->j_first_fc = journal->j_last + 1;
+ journal->j_fc_off = 0;
+ } else {
+ journal->j_last = last;
+ }
+
+ journal->j_head = journal->j_first;
+ journal->j_tail = journal->j_first;
+ journal->j_free = journal->j_last - journal->j_first;
journal->j_tail_sequence = journal->j_transaction_sequence;
journal->j_commit_sequence = journal->j_transaction_sequence - 1;
@@ -1626,22 +1637,21 @@ static int load_superblock(journal_t *journal)
journal->j_tail_sequence = be32_to_cpu(sb->s_sequence);
journal->j_tail = be32_to_cpu(sb->s_start);
journal->j_first = be32_to_cpu(sb->s_first);
- journal->j_last = be32_to_cpu(sb->s_maxlen);
journal->j_errno = be32_to_cpu(sb->s_errno);
+ if (jbd2_has_feature_fast_commit(journal)) {
+ journal->j_last_fc = be32_to_cpu(sb->s_maxlen);
+ journal->j_last = journal->j_last_fc - JBD2_FAST_COMMIT_BLOCKS;
+ journal->j_first_fc = journal->j_last + 1;
+ journal->j_fc_off = 0;
+ } else {
+ journal->j_last = be32_to_cpu(sb->s_maxlen);
+ }
+
return 0;
}
-
-/**
- * int jbd2_journal_load() - Read journal from disk.
- * @journal: Journal to act on.
- *
- * Given a journal_t structure which tells us which disk blocks contain
- * a journal, read the journal from disk to initialise the in-memory
- * structures.
- */
-int jbd2_journal_load(journal_t *journal)
+static int __jbd2_journal_load(journal_t *journal, bool enable_fc)
{
int err;
journal_superblock_t *sb;
@@ -1684,6 +1694,12 @@ int jbd2_journal_load(journal_t *journal)
return -EFSCORRUPTED;
}
+ if (enable_fc)
+ jbd2_journal_set_features(journal, 0, 0,
+ JBD2_FEATURE_INCOMPAT_FAST_COMMIT);
+ else
+ jbd2_journal_clear_features(journal, 0, 0,
+ JBD2_FEATURE_INCOMPAT_FAST_COMMIT);
/* OK, we've finished with the dynamic journal bits:
* reinitialise the dynamic contents of the superblock in memory
* and reset them on disk. */
@@ -1699,6 +1715,26 @@ int jbd2_journal_load(journal_t *journal)
return -EIO;
}
+/**
+ * int jbd2_journal_load() - Read journal from disk.
+ * @journal: Journal to act on.
+ *
+ * Given a journal_t structure which tells us which disk blocks contain
+ * a journal, read the journal from disk to initialise the in-memory
+ * structures.
+ */
+int jbd2_journal_load(journal_t *journal)
+{
+ return __jbd2_journal_load(journal, false);
+}
+
+/* Same as above but also enables fast commits. */
+int jbd2_journal_load_with_fc(journal_t *journal)
+{
+ return __jbd2_journal_load(journal, true);
+}
+
+
/**
* void jbd2_journal_destroy() - Release a journal_t structure.
* @journal: Journal to act on.
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index b7eed49b8ecd..84d04e1f3d92 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -67,6 +67,7 @@ extern void *jbd2_alloc(size_t size, gfp_t flags);
extern void jbd2_free(void *ptr, size_t size);
#define JBD2_MIN_JOURNAL_BLOCKS 1024
+#define JBD2_FAST_COMMIT_BLOCKS 128
#ifdef __KERNEL__
@@ -918,6 +919,30 @@ struct journal_s
*/
unsigned long j_last;
+ /**
+ * @j_first_fc:
+ *
+ * The block number of the first fast commit block in the journal
+ * [j_state_lock].
+ */
+ unsigned long j_first_fc;
+
+ /**
+ * @j_fc_off:
+ *
+ * Number of fast commit blocks currently allocated.
+ * [j_state_lock].
+ */
+ unsigned long j_fc_off;
+
+ /**
+ * @j_last_fc:
+ *
+ * The block number one beyond the last fast commit block in the journal
+ * [j_state_lock].
+ */
+ unsigned long j_last_fc;
+
/**
* @j_dev: Device where we store the journal.
*/
@@ -1061,6 +1086,12 @@ struct journal_s
*/
struct buffer_head **j_wbuf;
+ /**
+ * @j_fc_wbuf: Array of fast commit bhs for
+ * jbd2_journal_commit_transaction.
+ */
+ struct buffer_head **j_fc_wbuf;
+
/**
* @j_wbufsize:
*
@@ -1068,6 +1099,13 @@ struct journal_s
*/
int j_wbufsize;
+ /**
+ * @j_fc_wbufsize:
+ *
+ * Size of @j_fc_wbuf array.
+ */
+ int j_fc_wbufsize;
+
/**
* @j_last_sync_writer:
*
@@ -1398,6 +1436,7 @@ extern int jbd2_journal_set_features
extern void jbd2_journal_clear_features
(journal_t *, unsigned long, unsigned long, unsigned long);
extern int jbd2_journal_load (journal_t *journal);
+extern int jbd2_journal_load_with_fc(journal_t *journal);
extern int jbd2_journal_destroy (journal_t *);
extern int jbd2_journal_recover (journal_t *journal);
extern int jbd2_journal_wipe (journal_t *, int);
--
2.23.0.444.g18eeb5a265-goog
