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From: Minchan Kim <minchan@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, Nitin Gupta <ngupta@vflare.org>,
	Jerome Marchand <jmarchan@redhat.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Minchan Kim <minchan@kernel.org>
Subject: [PATCH 2/7] zram: delay pending free request in read path
Date: Mon, 13 Jan 2014 20:18:57 +0900	[thread overview]
Message-ID: <1389611942-15544-3-git-send-email-minchan@kernel.org> (raw)
In-Reply-To: <1389611942-15544-1-git-send-email-minchan@kernel.org>

Sergey Senozhatsky reporetd we don't need to handle pending free
request every I/O so that this patch removes it in read path while
we remain it in write path.

Let's consider below example.

Swap subsystem ask to zram "A" block free by swap_slot_free_notify
but zram had been pended it without real freeing.
Swap subsystem allocates "A" block for new data but request pended
for a long time just handled and zram blindly free new data on
the "A" block. :(

That's why we couldn't remove handle pending free request right before
zram-write.

Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 drivers/block/zram/zram_drv.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 213dfc1..d87c7e9 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -535,7 +535,6 @@ static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
 
 	if (rw == READ) {
 		down_read(&zram->lock);
-		handle_pending_slot_free(zram);
 		ret = zram_bvec_read(zram, bvec, index, offset, bio);
 		up_read(&zram->lock);
 	} else {
-- 
1.8.4.3


  parent reply	other threads:[~2014-01-13 11:21 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-01-13 11:18 [PATCH 0/7] zram bug fix and lock redesign Minchan Kim
2014-01-13 11:18 ` [PATCH 1/7] zram: fix race between reset and flushing pending work Minchan Kim
2014-01-13 23:55   ` Andrew Morton
2014-01-14  0:15     ` Minchan Kim
2014-01-14  7:14     ` Sergey Senozhatsky
2014-01-13 11:18 ` Minchan Kim [this message]
2014-01-13 11:18 ` [PATCH 3/7] zram: remove unnecessary free Minchan Kim
2014-01-13 11:18 ` [PATCH 4/7] zram: use atomic operation for stat Minchan Kim
2014-01-13 23:58   ` Andrew Morton
2014-01-14  0:19     ` Minchan Kim
2014-01-14  0:23       ` Andrew Morton
2014-01-14  0:38         ` Minchan Kim
2014-01-13 11:19 ` [PATCH 5/7] zram: introduce zram->tb_lock Minchan Kim
2014-01-13 11:19 ` [PATCH 6/7] zram: remove workqueue for freeing removed pending slot Minchan Kim
2014-01-13 19:42   ` Sergey Senozhatsky
2014-01-13 23:38     ` Minchan Kim
2014-01-14  7:09       ` Sergey Senozhatsky
2014-01-13 11:19 ` [PATCH 7/7] zram: remove unnecessary lock Minchan Kim
2014-01-14  9:29   ` Jerome Marchand
2014-01-15  1:34     ` Minchan Kim

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