----- Original Message ----- > From: "Sergey Senozhatsky" <sergey.senozhat...@gmail.com> > To: "Minchan Kim" <minc...@kernel.org> > Cc: "Jens Axboe" <ax...@kernel.dk>, "Hyeoncheol Lee" <cheol....@lge.com>, > linux-bl...@vger.kernel.org, > linux-kernel@vger.kernel.org, "Andrew Morton" <a...@linux-foundation.org>, > "Sergey Senozhatsky" > <sergey.senozhat...@gmail.com>, "Robert Jennings" <r...@linux.vnet.ibm.com>, > "Jerome Marchand" <jmarc...@redhat.com> > Sent: Monday, January 9, 2017 3:33:44 PM > Subject: Re: [RFC] blk: increase logical_block_size to unsigned int > > On (01/09/17 14:04), Minchan Kim wrote: > > Mostly, zram is used as swap system on embedded world so it want to do IO > > as PAGE_SIZE aligned/size IO unit. For that, one of the problem was > > blk_queue_logical_block_size(zram->disk->queue, PAGE_SIZE) made overflow > > in *64K page system* so [1] changed it to constant 4096. > > Since that, partial IO can happen so zram should handle it which makes zram > > complicated[2]. > > > > I thought that zram partial IO support is there because some file > systems cannot cope with large logical_block_size. like FAT, for > example. am I wrong?
Yes indeed. When we discussed the patch adding the partial I/O, increasing the size of logical_block was considered. The reason we didn't go the easy path was that not all block users could handle 64k blocks. FAT is one of them. Jerome > > -ss >
