linux/drivers/block/zram
Sergey Senozhatsky ba6b17d68c zram: fix umount-reset_store-mount race condition
Ganesh Mahendran was the first one who proposed to use bdev->bd_mutex to
avoid ->bd_holders race condition:

        CPU0                            CPU1
umount /* zram->init_done is true */
reset_store()
bdev->bd_holders == 0                   mount
...                                     zram_make_request()
zram_reset_device()

However, his solution required some considerable amount of code movement,
which we can avoid.

Apart from using bdev->bd_mutex in reset_store(), this patch also
simplifies zram_reset_device().

zram_reset_device() has a bool parameter reset_capacity which tells it
whether disk capacity and itself disk should be reset.  There are two
zram_reset_device() callers:

-- zram_exit() passes reset_capacity=false
-- reset_store() passes reset_capacity=true

So we can move reset_capacity-sensitive work out of zram_reset_device()
and perform it unconditionally in reset_store().  This also lets us drop
reset_capacity parameter from zram_reset_device() and pass zram pointer
only.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Reported-by: Ganesh Mahendran <opensource.ganesh@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 18:54:11 -08:00
..
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_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
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
zram_drv.c zram: fix umount-reset_store-mount race condition 2015-02-12 18:54:11 -08:00
zram_drv.h mm/zram: correct ZRAM_ZERO flag bit position 2014-12-13 12:42:50 -08:00