shithub: lwext4

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ext4_journal: tune the logic of block zeroing in write_commit_block()

--- a/src/ext4_journal.c

+++ b/src/ext4_journal.c

@@ -1763,7 +1763,25 @@

 	struct jbd_journal *journal = trans->journal;

 	commit_iblock = jbd_journal_alloc_block(journal, trans);

-	rc = jbd_block_get_noread(journal->jbd_fs, &block, commit_iblock);

+	orig_commit_iblock = commit_iblock;

+	commit_iblock++;

+	wrap(&journal->jbd_fs->sb, commit_iblock);

+

+	/* To prevent accidental reference to stale journalling metadata. */

+	if (orig_commit_iblock < commit_iblock) {

+		rc = jbd_block_get_noread(journal->jbd_fs, &block, commit_iblock);

+		if (rc != EOK)

+			return rc;

+

+		memset(block.data, 0, journal->block_size);

+		ext4_bcache_set_dirty(block.buf);

+		ext4_bcache_set_flag(block.buf, BC_TMP);

+		rc = jbd_block_set(journal->jbd_fs, &block);

+		if (rc != EOK)

+			return rc;

+	}

+

+	rc = jbd_block_get_noread(journal->jbd_fs, &block, orig_commit_iblock);

 	if (rc != EOK)

 		return rc;

@@ -1782,25 +1800,6 @@

 	ext4_bcache_set_dirty(block.buf);

 	ext4_bcache_set_flag(block.buf, BC_TMP);

 	rc = jbd_block_set(journal->jbd_fs, &block);

-	if (rc != EOK)

-		return rc;

-

-	orig_commit_iblock = commit_iblock;

-	commit_iblock++;

-	wrap(&journal->jbd_fs->sb, commit_iblock);

-

-	/* To prevent accidental reference to stale journalling metadata. */

-	if (orig_commit_iblock < commit_iblock) {

-		rc = jbd_block_get_noread(journal->jbd_fs, &block, commit_iblock);

-		if (rc != EOK)

-			return rc;

-

-		memset(block.data, 0, journal->block_size);

-		ext4_bcache_set_dirty(block.buf);

-		ext4_bcache_set_flag(block.buf, BC_TMP);

-		rc = jbd_block_set(journal->jbd_fs, &block);

-	}

-

 	return rc;

 }