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authorTheodore Ts'o <tytso@mit.edu>2009-09-11 09:30:12 -0400
committerTheodore Ts'o <tytso@mit.edu>2009-09-11 09:30:12 -0400
commit0e3d2a6313d03413d93327202a60256d1d726fdc (patch)
tree3b4165751568e4332edad89a82e76bc6708c8ccd /fs/jbd2
parent71290b368ad5e1e0b0b300c9d5638490a9fd1a2d (diff)
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" <tytso@mit.edu>
Diffstat (limited to 'fs/jbd2')
-rw-r--r--fs/jbd2/commit.c11
1 files changed, 7 insertions, 4 deletions
diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index 0df600e9162..26d991ddc1e 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -25,6 +25,7 @@
25#include <linux/writeback.h> 25#include <linux/writeback.h>
26#include <linux/backing-dev.h> 26#include <linux/backing-dev.h>
27#include <linux/bio.h> 27#include <linux/bio.h>
28#include <linux/blkdev.h>
28#include <trace/events/jbd2.h> 29#include <trace/events/jbd2.h>
29 30
30/* 31/*
@@ -133,8 +134,8 @@ static int journal_submit_commit_record(journal_t *journal,
133 bh->b_end_io = journal_end_buffer_io_sync; 134 bh->b_end_io = journal_end_buffer_io_sync;
134 135
135 if (journal->j_flags & JBD2_BARRIER && 136 if (journal->j_flags & JBD2_BARRIER &&
136 !JBD2_HAS_INCOMPAT_FEATURE(journal, 137 !JBD2_HAS_INCOMPAT_FEATURE(journal,
137 JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) { 138 JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
138 set_buffer_ordered(bh); 139 set_buffer_ordered(bh);
139 barrier_done = 1; 140 barrier_done = 1;
140 } 141 }
@@ -706,11 +707,13 @@ start_journal_io:
706 /* Done it all: now write the commit record asynchronously. */ 707 /* Done it all: now write the commit record asynchronously. */
707 708
708 if (JBD2_HAS_INCOMPAT_FEATURE(journal, 709 if (JBD2_HAS_INCOMPAT_FEATURE(journal,
709 JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) { 710 JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
710 err = journal_submit_commit_record(journal, commit_transaction, 711 err = journal_submit_commit_record(journal, commit_transaction,
711 &cbh, crc32_sum); 712 &cbh, crc32_sum);
712 if (err) 713 if (err)
713 __jbd2_journal_abort_hard(journal); 714 __jbd2_journal_abort_hard(journal);
715 if (journal->j_flags & JBD2_BARRIER)
716 blkdev_issue_flush(journal->j_dev, NULL);
714 } 717 }
715 718
716 /* 719 /*
@@ -833,7 +836,7 @@ wait_for_iobuf:
833 jbd_debug(3, "JBD: commit phase 5\n"); 836 jbd_debug(3, "JBD: commit phase 5\n");
834 837
835 if (!JBD2_HAS_INCOMPAT_FEATURE(journal, 838 if (!JBD2_HAS_INCOMPAT_FEATURE(journal,
836 JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) { 839 JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
837 err = journal_submit_commit_record(journal, commit_transaction, 840 err = journal_submit_commit_record(journal, commit_transaction,
838 &cbh, crc32_sum); 841 &cbh, crc32_sum);
839 if (err) 842 if (err)