For NAND based SSDs, mixing of data with different life-time reduces efficiency of internal garbage-collection. During FS operations, series of journal updates will follow/precede series of data/meta updates, causing intermixing inside SSD. By passing a write-hint with journal, its write can be isolated from other data/meta writes, leading to endurance/performance benefit on SSD.
This patch introduces "j_writehint" member in JBD2 journal, using which Ext4 specifies write-hint (as SHORT) for journal. Signed-off-by: Kanchan Joshi <[email protected]> --- fs/ext4/super.c | 2 ++ fs/jbd2/commit.c | 11 +++++++---- fs/jbd2/journal.c | 3 ++- fs/jbd2/revoke.c | 3 ++- include/linux/jbd2.h | 8 ++++++++ 5 files changed, 21 insertions(+), 6 deletions(-) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index d6c142d..3af4049 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -4289,6 +4289,8 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) set_task_ioprio(sbi->s_journal->j_task, journal_ioprio); + sbi->s_journal->j_writehint = KERN_WRITE_LIFE_SHORT; + sbi->s_journal->j_commit_callback = ext4_journal_commit_callback; no_journal: diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c index 2eb55c3..6da4c28 100644 --- a/fs/jbd2/commit.c +++ b/fs/jbd2/commit.c @@ -153,10 +153,12 @@ static int journal_submit_commit_record(journal_t *journal, if (journal->j_flags & JBD2_BARRIER && !jbd2_has_feature_async_commit(journal)) - ret = submit_bh(REQ_OP_WRITE, - REQ_SYNC | REQ_PREFLUSH | REQ_FUA, bh); + ret = submit_bh_write_hint(REQ_OP_WRITE, + REQ_SYNC | REQ_PREFLUSH | REQ_FUA, bh, + journal->j_writehint); else - ret = submit_bh(REQ_OP_WRITE, REQ_SYNC, bh); + ret = submit_bh_write_hint(REQ_OP_WRITE, REQ_SYNC, bh, + journal->j_writehint); *cbh = bh; return ret; @@ -711,7 +713,8 @@ void jbd2_journal_commit_transaction(journal_t *journal) clear_buffer_dirty(bh); set_buffer_uptodate(bh); bh->b_end_io = journal_end_buffer_io_sync; - submit_bh(REQ_OP_WRITE, REQ_SYNC, bh); + submit_bh_write_hint(REQ_OP_WRITE, REQ_SYNC, + bh, journal->j_writehint); } cond_resched(); stats.run.rs_blocks_logged += bufs; diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c index 8ef6b6d..804dc2c 100644 --- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -1384,7 +1384,8 @@ static int jbd2_write_superblock(journal_t *journal, int write_flags) jbd2_superblock_csum_set(journal, sb); get_bh(bh); bh->b_end_io = end_buffer_write_sync; - ret = submit_bh(REQ_OP_WRITE, write_flags, bh); + ret = submit_bh_write_hint(REQ_OP_WRITE, write_flags, bh, + journal->j_writehint); wait_on_buffer(bh); if (buffer_write_io_error(bh)) { clear_buffer_write_io_error(bh); diff --git a/fs/jbd2/revoke.c b/fs/jbd2/revoke.c index a1143e5..376b1d8 100644 --- a/fs/jbd2/revoke.c +++ b/fs/jbd2/revoke.c @@ -642,7 +642,8 @@ static void flush_descriptor(journal_t *journal, set_buffer_jwrite(descriptor); BUFFER_TRACE(descriptor, "write"); set_buffer_dirty(descriptor); - write_dirty_buffer(descriptor, REQ_SYNC); + write_dirty_buffer_with_hint(descriptor, REQ_SYNC, + journal->j_writehint); } #endif diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h index 0f919d5..918f21e 100644 --- a/include/linux/jbd2.h +++ b/include/linux/jbd2.h @@ -1139,6 +1139,14 @@ struct journal_s */ __u32 j_csum_seed; + /** + * @j_writehint: + * + * write-hint for journal (set by FS). + */ + enum rw_hint j_writehint; + + #ifdef CONFIG_DEBUG_LOCK_ALLOC /** * @j_trans_commit_map: -- 2.7.4
