Subject: + zram-support-req_discard.patch added to -mm tree
To: iamjoonsoo.kim@xxxxxxx,jmarchan@xxxxxxxxxx,minchan@xxxxxxxxxx,ngupta@xxxxxxxxxx,sergey.senozhatsky@xxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Wed, 12 Mar 2014 13:33:27 -0700
The patch titled
Subject: zram: support REQ_DISCARD
has been added to the -mm tree. Its filename is
zram-support-req_discard.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/zram-support-req_discard.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/zram-support-req_discard.patch
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From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Subject: zram: support REQ_DISCARD
zram is ram based block device and can be used by backend of filesystem.
When filesystem deletes a file, it normally doesn't do anything on data
block of that file. It just marks on metadata of that file. This
behavior has no problem on disk based block device, but has problems on
ram based block device, since we can't free memory used for data block.
To overcome this disadvantage, there is REQ_DISCARD functionality. If
block device support REQ_DISCARD and filesystem is mounted with discard
option, filesystem sends REQ_DISCARD to block device whenever some data
blocks are discarded. All we have to do is to handle this request.
This patch implements to flag up QUEUE_FLAG_DISCARD and handle this
REQ_DISCARD request. With it, we can free memory used by zram if it isn't
used.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Nitin Gupta <ngupta@xxxxxxxxxx>
Cc: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Cc: Jerome Marchand <jmarchan@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/block/zram/zram_drv.c | 44 ++++++++++++++++++++++++++++++++
1 file changed, 44 insertions(+)
diff -puN drivers/block/zram/zram_drv.c~zram-support-req_discard drivers/block/zram/zram_drv.c
--- a/drivers/block/zram/zram_drv.c~zram-support-req_discard
+++ a/drivers/block/zram/zram_drv.c
@@ -550,6 +550,33 @@ static int zram_bvec_rw(struct zram *zra
return ret;
}
+static void zram_bio_discard(struct zram *zram, u32 index,
+ int offset, struct bio *bio)
+{
+ size_t n = bio->bi_iter.bi_size;
+
+ /*
+ * On some arch, logical block (4096) aligned request couldn't be
+ * aligned to PAGE_SIZE, since their PAGE_SIZE aren't 4096.
+ * Therefore we should handle this misaligned case here.
+ */
+ if (offset) {
+ if (n < offset)
+ return;
+
+ n -= offset;
+ index++;
+ }
+
+ while (n >= PAGE_SIZE) {
+ write_lock(&zram->meta->tb_lock);
+ zram_free_page(zram, index);
+ write_unlock(&zram->meta->tb_lock);
+ index++;
+ n -= PAGE_SIZE;
+ }
+}
+
static void zram_reset_device(struct zram *zram, bool reset_capacity)
{
size_t index;
@@ -685,6 +712,12 @@ static void __zram_make_request(struct z
offset = (bio->bi_iter.bi_sector &
(SECTORS_PER_PAGE - 1)) << SECTOR_SHIFT;
+ if (unlikely(bio->bi_rw & REQ_DISCARD)) {
+ zram_bio_discard(zram, index, offset, bio);
+ bio_endio(bio, 0);
+ return;
+ }
+
bio_for_each_segment(bvec, bio, iter) {
int max_transfer_size = PAGE_SIZE - offset;
@@ -854,6 +887,17 @@ static int create_device(struct zram *zr
ZRAM_LOGICAL_BLOCK_SIZE);
blk_queue_io_min(zram->disk->queue, PAGE_SIZE);
blk_queue_io_opt(zram->disk->queue, PAGE_SIZE);
+ zram->disk->queue->limits.discard_granularity = PAGE_SIZE;
+ zram->disk->queue->limits.max_discard_sectors = UINT_MAX;
+ /*
+ * We will skip to discard mis-aligned range, so we can't ensure
+ * whether discarded region is zero or not.
+ */
+ if (ZRAM_LOGICAL_BLOCK_SIZE == PAGE_SIZE)
+ zram->disk->queue->limits.discard_zeroes_data = 1;
+ else
+ zram->disk->queue->limits.discard_zeroes_data = 0;
+ queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, zram->disk->queue);
add_disk(zram->disk);
_
Patches currently in -mm which might be from iamjoonsoo.kim@xxxxxxx are
origin.patch
kthread-ensure-locality-of-task_struct-allocations.patch
slub-fix-high-order-page-allocation-problem-with-__gfp_nofail.patch
mm-hugetlb-unify-region-structure-handling.patch
mm-hugetlb-improve-cleanup-resv_map-parameters.patch
mm-hugetlb-fix-race-in-region-tracking.patch
mm-hugetlb-remove-resv_map_put.patch
mm-hugetlb-use-vma_resv_map-map-types.patch
mm-hugetlb-improve-page-fault-scalability.patch
mm-hugetlb-improve-page-fault-scalability-fix.patch
mm-hugetlb-mark-some-bootstrap-functions-as-__init.patch
mm-compaction-avoid-isolating-pinned-pages.patch
mm-compaction-disallow-high-order-page-for-migration-target.patch
mm-compaction-do-not-call-suitable_migration_target-on-every-page.patch
mm-compaction-change-the-timing-to-check-to-drop-the-spinlock.patch
mm-compaction-check-pageblock-suitability-once-per-pageblock.patch
mm-compaction-clean-up-code-on-success-of-ballon-isolation.patch
mm-compactionc-isolate_freepages_block-small-tuneup.patch
mm-compaction-determine-isolation-mode-only-once.patch
mm-vmallocc-enhance-vm_map_ram-comment.patch
mm-vmallocc-enhance-vm_map_ram-comment-fix.patch
zram-support-req_discard.patch
page-owners-correct-page-order-when-to-free-page.patch
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