1 files changed, 158 insertions, 0 deletions

diff --git a/patches/boot_time_opt/0110-fs-ext4-fsync-optimize-double-fsync-a-bunch.patch b/patches/boot_time_opt/0110-fs-ext4-fsync-optimize-double-fsync-a-bunch.patch
new file mode 100644
index 0000000..b115a5b
--- /dev/null
+++ b/patches/boot_time_opt/0110-fs-ext4-fsync-optimize-double-fsync-a-bunch.patch
@@ -0,0 +1,158 @@
+From 5e6c814b3ab74e9abbdd836a224c5ceb7246b44e Mon Sep 17 00:00:00 2001
+From: Arjan van de Ven <arjan@linux.intel.com>
+Date: Sat, 9 Apr 2016 22:41:37 +0000
+Subject: [PATCH 110/126] fs: ext4: fsync: optimize double-fsync() a bunch
+
+There are cases where EXT4 is a bit too conservative sending barriers down to
+the disk; there are cases where the transaction in progress is not the one
+that sent the barrier (in other words: the fsync is for a file for which the
+IO happened more time ago and all data was already sent to the disk).
+
+For that case, a more performing tradeoff can be made on SSD devices (which
+have the ability to flush their dram caches in a hurry on a power fail event)
+where the barrier gets sent to the disk, but we don't need to wait for the
+barrier to complete. Any consecutive IO will block on the barrier correctly.
+---
+ block/bio.c            | 19 +++++++++++++++++++
+ block/blk-flush.c      | 40 ++++++++++++++++++++++++++++++++++++++++
+ fs/ext4/fsync.c        |  6 +++++-
+ include/linux/bio.h    |  1 +
+ include/linux/blkdev.h |  5 +++++
+ 5 files changed, 70 insertions(+), 1 deletion(-)
+
+diff --git a/block/bio.c b/block/bio.c
+index 101c2a9b5481..8f9f6e9febe0 100644
+--- a/block/bio.c
++++ b/block/bio.c
+@@ -956,6 +956,25 @@ int submit_bio_wait(struct bio *bio)
+ }
+ EXPORT_SYMBOL(submit_bio_wait);
+ 
++static void submit_bio_nowait_endio(struct bio *bio)
++{
++       bio_put(bio);
++}
++
++/**
++ * submit_bio_nowait - submit a bio for fire-and-forge for fire-and-forget
++ * @bio: The &struct bio which describes the I/O
++ *
++ * Simple wrapper around submit_bio() that takes care of bio_put() on completion
++ */
++void submit_bio_nowait(struct bio *bio)
++{
++       bio->bi_end_io = submit_bio_nowait_endio;
++       bio->bi_opf |= REQ_SYNC;
++       submit_bio(bio);
++}
++EXPORT_SYMBOL(submit_bio_nowait);
++
+ /**
+  * bio_advance - increment/complete a bio by some number of bytes
+  * @bio:       bio to advance
+diff --git a/block/blk-flush.c b/block/blk-flush.c
+index 4938bec8cfef..020f2c75343a 100644
+--- a/block/blk-flush.c
++++ b/block/blk-flush.c
+@@ -543,6 +543,46 @@ int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
+ }
+ EXPORT_SYMBOL(blkdev_issue_flush);
+ 
++/**
++ * blkdev_issue_flush_nowait - queue a flush
++ * @bdev:      blockdev to issue flush for
++ * @gfp_mask:  memory allocation flags (for bio_alloc)
++ *
++ * Description:
++ *    Issue a flush for the block device in question. Caller can supply
++ *    room for storing the error offset in case of a flush error, if they
++ *    wish to. If WAIT flag is not passed then caller may check only what
++ *    request was pushed in some internal queue for later handling.
++ */
++void blkdev_issue_flush_nowait(struct block_device *bdev, gfp_t gfp_mask)
++{
++       struct request_queue *q;
++       struct bio *bio;
++
++       if (bdev->bd_disk == NULL)
++               return;
++
++       q = bdev_get_queue(bdev);
++       if (!q)
++               return;
++
++       /*
++        * some block devices may not have their queue correctly set up here
++        * (e.g. loop device without a backing file) and so issuing a flush
++        * here will panic. Ensure there is a request function before issuing
++        * the flush.
++        */
++       if (!q->make_request_fn)
++               return;
++
++       bio = bio_alloc(gfp_mask, 0);
++       bio_set_dev(bio, bdev);
++       bio->bi_opf = REQ_OP_WRITE | REQ_PREFLUSH;
++
++       submit_bio_nowait(bio);
++}
++EXPORT_SYMBOL(blkdev_issue_flush_nowait);
++
+ struct blk_flush_queue *blk_alloc_flush_queue(struct request_queue *q,
+                int node, int cmd_size)
+ {
+diff --git a/fs/ext4/fsync.c b/fs/ext4/fsync.c
+index 26a7fe5c4fd3..2708b292ddca 100644
+--- a/fs/ext4/fsync.c
++++ b/fs/ext4/fsync.c
+@@ -154,7 +154,11 @@ int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
+        ret = jbd2_complete_transaction(journal, commit_tid);
+        if (needs_barrier) {
+        issue_flush:
+-               err = blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
++               err = 0;
++               if (!blk_queue_nonrot(bdev_get_queue(inode->i_sb->s_bdev)))
++                       err = blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
++               else
++                       blkdev_issue_flush_nowait(inode->i_sb->s_bdev, GFP_KERNEL);
+                if (!ret)
+                        ret = err;
+        }
+diff --git a/include/linux/bio.h b/include/linux/bio.h
+index 275c91c99516..4ddfa9e10301 100644
+--- a/include/linux/bio.h
++++ b/include/linux/bio.h
+@@ -448,6 +448,7 @@ struct request_queue;
+ extern int bio_phys_segments(struct request_queue *, struct bio *);
+ 
+ extern int submit_bio_wait(struct bio *bio);
++extern void submit_bio_nowait(struct bio *bio);
+ extern void bio_advance(struct bio *, unsigned);
+ 
+ extern void bio_init(struct bio *bio, struct bio_vec *table,
+diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
+index 8da66379f7ea..c48565cc84fb 100644
+--- a/include/linux/blkdev.h
++++ b/include/linux/blkdev.h
+@@ -1336,6 +1336,7 @@ static inline struct request *blk_map_queue_find_tag(struct blk_queue_tag *bqt,
+ }
+ 
+ extern int blkdev_issue_flush(struct block_device *, gfp_t, sector_t *);
++extern void blkdev_issue_flush_nowait(struct block_device *, gfp_t);
+ extern int blkdev_issue_write_same(struct block_device *bdev, sector_t sector,
+                sector_t nr_sects, gfp_t gfp_mask, struct page *page);
+ 
+@@ -2001,6 +2002,10 @@ static inline int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
+        return 0;
+ }
+ 
++static inline void blkdev_issue_flush_nowait(struct block_device *bdev, gfp_t gfp_mask)
++{
++}
++
+ #endif /* CONFIG_BLOCK */
+ 
+ #endif
+-- 
+2.15.0
+