zram: delay pending free request in read path
authorMinchan Kim <minchan@kernel.org>
Thu, 30 Jan 2014 23:46:00 +0000 (15:46 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 31 Jan 2014 00:56:55 +0000 (16:56 -0800)
commit9b353db16d18f87242337e3e61a948c023505a65
treeea24f4859c670b58f416ad423d70343f3aeb752f
parentda4a04126baa3be03bc566d4a2ee0944c5e783d0
zram: delay pending free request in read path

Sergey reported 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>
Reported-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Tested-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
drivers/block/zram/zram_drv.c