path: root/lib
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authorJoonsoo Kim <iamjoonsoo.kim@lge.com>2014-04-07 15:38:24 -0700
committerAlex Shi <alex.shi@linaro.org>2015-05-11 20:56:20 +0800
commitba6d7663fa3c9b310f33b9b8a18743af8b3727c9 (patch)
tree0609807cb8d9b9353ca23e41e8171b2737d6db56 /lib
parent575ef7bc322df6e0384ef661f510928bfa1dab81 (diff)
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> (cherry picked from commit f4659d8e620d08bd1a84a8aec5d2f5294a242764) Signed-off-by: Alex Shi <alex.shi@linaro.org> Conflicts: drivers/block/zram/zram_drv.c Conflicts solution: keep use old bio struct, and bio_for_each_segment()
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