From 0e3d2a6313d03413d93327202a60256d1d726fdc Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Fri, 11 Sep 2009 09:30:12 -0400 Subject: [PATCH] ext4: Fix async commit mode to be safe by using a barrier Previously the journal_async_commit mount option was equivalent to using barrier=0 (and just as unsafe). This patch fixes it so that we eliminate the barrier before the commit block (by not using ordered mode), and explicitly issuing an empty barrier bio after writing the commit block. Because of the journal checksum, it is safe to do this; if the journal blocks are not all written before a power failure, the checksum in the commit block will prevent the last transaction from being replayed. Using the fs_mark benchmark, using journal_async_commit shows a 50% improvement: FSUse% Count Size Files/sec App Overhead 8 1000 10240 30.5 28242 vs. FSUse% Count Size Files/sec App Overhead 8 1000 10240 45.8 28620 Signed-off-by: "Theodore Ts'o" --- fs/jbd2/commit.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c index 0df600e9162d..26d991ddc1e6 100644 --- a/fs/jbd2/commit.c +++ b/fs/jbd2/commit.c @@ -25,6 +25,7 @@ #include #include #include +#include #include /* @@ -133,8 +134,8 @@ static int journal_submit_commit_record(journal_t *journal, bh->b_end_io = journal_end_buffer_io_sync; if (journal->j_flags & JBD2_BARRIER && - !JBD2_HAS_INCOMPAT_FEATURE(journal, - JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) { + !JBD2_HAS_INCOMPAT_FEATURE(journal, + JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) { set_buffer_ordered(bh); barrier_done = 1; } @@ -706,11 +707,13 @@ start_journal_io: /* Done it all: now write the commit record asynchronously. */ if (JBD2_HAS_INCOMPAT_FEATURE(journal, - JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) { + JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) { err = journal_submit_commit_record(journal, commit_transaction, &cbh, crc32_sum); if (err) __jbd2_journal_abort_hard(journal); + if (journal->j_flags & JBD2_BARRIER) + blkdev_issue_flush(journal->j_dev, NULL); } /* @@ -833,7 +836,7 @@ wait_for_iobuf: jbd_debug(3, "JBD: commit phase 5\n"); if (!JBD2_HAS_INCOMPAT_FEATURE(journal, - JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) { + JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) { err = journal_submit_commit_record(journal, commit_transaction, &cbh, crc32_sum); if (err) -- 2.20.1