From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754952Ab0HITDx (ORCPT ); Mon, 9 Aug 2010 15:03:53 -0400 Received: from mail-gx0-f174.google.com ([209.85.161.174]:61714 "EHLO mail-gx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753771Ab0HITDv convert rfc822-to-8bit (ORCPT ); Mon, 9 Aug 2010 15:03:51 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type :content-transfer-encoding; b=eEhnN3PtpJ/Ss4fRNStW0sYDg6eJA6tKC/MNwmiUjG021vRgH8RskKEJqDz5ht1/yy 13CxaZmABvmYjeI6i5RDT4Ux8sd+Xr9dwZ5IcMeukfZOfebp03mNQCHCbdUQXH9IHdnW gE2cloYoT58rp1iu1zRIRCX6nOoH+dOfnqg4s= MIME-Version: 1.0 In-Reply-To: <1281374816-904-7-git-send-email-ngupta@vflare.org> References: <1281374816-904-1-git-send-email-ngupta@vflare.org> <1281374816-904-7-git-send-email-ngupta@vflare.org> Date: Mon, 9 Aug 2010 22:03:50 +0300 X-Google-Sender-Auth: 1NkhaStaX4oiDeWPnp8WzW2yBiw Message-ID: Subject: Re: [PATCH 06/10] Block discard support From: Pekka Enberg To: Nitin Gupta Cc: Pekka Enberg , Minchan Kim , Andrew Morton , Greg KH , Linux Driver Project , linux-mm , linux-kernel , linux-fsdevel@vger.kernel.org, jaxboe@fusionio.com Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Aug 9, 2010 at 8:26 PM, Nitin Gupta wrote: > The 'discard' bio discard request provides information to > zram disks regarding blocks which are no longer in use by > filesystem. This allows freeing memory allocated for such > blocks. > > When zram devices are used as swap disks, we already have > a callback (block_device_operations->swap_slot_free_notify). > So, the discard support is useful only when used as generic > (non-swap) disk. > > Signed-off-by: Nitin Gupta Lets CC fsdevel and Jens for this. > --- >  drivers/staging/zram/zram_drv.c   |   25 +++++++++++++++++++++++++ >  drivers/staging/zram/zram_sysfs.c |   11 +++++++++++ >  2 files changed, 36 insertions(+), 0 deletions(-) > > diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c > index efe9c93..0f9785f 100644 > --- a/drivers/staging/zram/zram_drv.c > +++ b/drivers/staging/zram/zram_drv.c > @@ -420,6 +420,20 @@ out: >        return 0; >  } > > +static void zram_discard(struct zram *zram, struct bio *bio) > +{ > +       size_t bytes = bio->bi_size; > +       sector_t sector = bio->bi_sector; > + > +       while (bytes >= PAGE_SIZE) { > +               zram_free_page(zram, sector >> SECTORS_PER_PAGE_SHIFT); > +               sector += PAGE_SIZE >> SECTOR_SHIFT; > +               bytes -= PAGE_SIZE; > +       } > + > +       bio_endio(bio, 0); > +} > + >  /* >  * Check if request is within bounds and page aligned. >  */ > @@ -451,6 +465,12 @@ static int zram_make_request(struct request_queue *queue, struct bio *bio) >                return 0; >        } > > +       if (unlikely(bio_rw_flagged(bio, BIO_RW_DISCARD))) { > +               zram_inc_stat(zram, ZRAM_STAT_DISCARD); > +               zram_discard(zram, bio); > +               return 0; > +       } > + >        switch (bio_data_dir(bio)) { >        case READ: >                ret = zram_read(zram, bio); > @@ -606,6 +626,11 @@ static int create_device(struct zram *zram, int device_id) >        blk_queue_io_min(zram->disk->queue, PAGE_SIZE); >        blk_queue_io_opt(zram->disk->queue, PAGE_SIZE); > > +       zram->disk->queue->limits.discard_granularity = PAGE_SIZE; > +       zram->disk->queue->limits.max_discard_sectors = UINT_MAX; > +       zram->disk->queue->limits.discard_zeroes_data = 1; > +       queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, zram->queue); > + >        add_disk(zram->disk); > >  #ifdef CONFIG_SYSFS > diff --git a/drivers/staging/zram/zram_sysfs.c b/drivers/staging/zram/zram_sysfs.c > index 43bcdd4..74971c0 100644 > --- a/drivers/staging/zram/zram_sysfs.c > +++ b/drivers/staging/zram/zram_sysfs.c > @@ -165,6 +165,15 @@ static ssize_t notify_free_show(struct device *dev, >                zram_get_stat(zram, ZRAM_STAT_NOTIFY_FREE)); >  } > > +static ssize_t discard_show(struct device *dev, > +               struct device_attribute *attr, char *buf) > +{ > +       struct zram *zram = dev_to_zram(dev); > + > +       return sprintf(buf, "%llu\n", > +               zram_get_stat(zram, ZRAM_STAT_DISCARD)); > +} > + >  static ssize_t zero_pages_show(struct device *dev, >                struct device_attribute *attr, char *buf) >  { > @@ -215,6 +224,7 @@ static DEVICE_ATTR(num_reads, S_IRUGO, num_reads_show, NULL); >  static DEVICE_ATTR(num_writes, S_IRUGO, num_writes_show, NULL); >  static DEVICE_ATTR(invalid_io, S_IRUGO, invalid_io_show, NULL); >  static DEVICE_ATTR(notify_free, S_IRUGO, notify_free_show, NULL); > +static DEVICE_ATTR(discard, S_IRUGO, discard_show, NULL); >  static DEVICE_ATTR(zero_pages, S_IRUGO, zero_pages_show, NULL); >  static DEVICE_ATTR(orig_data_size, S_IRUGO, orig_data_size_show, NULL); >  static DEVICE_ATTR(compr_data_size, S_IRUGO, compr_data_size_show, NULL); > @@ -228,6 +238,7 @@ static struct attribute *zram_disk_attrs[] = { >        &dev_attr_num_writes.attr, >        &dev_attr_invalid_io.attr, >        &dev_attr_notify_free.attr, > +       &dev_attr_discard.attr, >        &dev_attr_zero_pages.attr, >        &dev_attr_orig_data_size.attr, >        &dev_attr_compr_data_size.attr, > -- > 1.7.2.1 > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org.  For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: email@kvack.org >