linux/drivers/block/zram
Joonsoo Kim f4659d8e62 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.

[akpm@linux-foundation.org: tweak comments]
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-07 16:36:02 -07:00
..
Kconfig zram: add lz4 algorithm backend 2014-04-07 16:36:01 -07:00
Makefile zram: add lz4 algorithm backend 2014-04-07 16:36:01 -07:00
zcomp.c zram: use scnprintf() in attrs show() methods 2014-04-07 16:36:02 -07:00
zcomp.h zram: propagate error to user 2014-04-07 16:36:02 -07:00
zcomp_lz4.c zram: add lz4 algorithm backend 2014-04-07 16:36:01 -07:00
zcomp_lz4.h zram: add lz4 algorithm backend 2014-04-07 16:36:01 -07:00
zcomp_lzo.c zram: introduce compressing backend abstraction 2014-04-07 16:36:01 -07:00
zcomp_lzo.h zram: introduce compressing backend abstraction 2014-04-07 16:36:01 -07:00
zram_drv.c zram: support REQ_DISCARD 2014-04-07 16:36:02 -07:00
zram_drv.h zram: make compression algorithm selection possible 2014-04-07 16:36:01 -07:00