From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57583) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VT68u-0000Ab-0S for qemu-devel@nongnu.org; Mon, 07 Oct 2013 04:26:21 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VT68n-0005ov-Uu for qemu-devel@nongnu.org; Mon, 07 Oct 2013 04:26:15 -0400 Received: from mail-ee0-x229.google.com ([2a00:1450:4013:c00::229]:61829) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VT68n-0005ma-GK for qemu-devel@nongnu.org; Mon, 07 Oct 2013 04:26:09 -0400 Received: by mail-ee0-f41.google.com with SMTP id d17so3090028eek.28 for ; Mon, 07 Oct 2013 01:26:08 -0700 (PDT) Sender: Paolo Bonzini Message-ID: <52527015.4090103@redhat.com> Date: Mon, 07 Oct 2013 10:25:57 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1381125551-24354-1-git-send-email-pl@kamp.de> In-Reply-To: <1381125551-24354-1-git-send-email-pl@kamp.de> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCHv5] block/get_block_status: avoid redundant callouts on raw devices List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Lieven Cc: kwolf@redhat.com, anthony@codemonkey.ws, stefanha@redhat.com, qemu-devel@nongnu.org, ronniesahlberg@gmail.com Il 07/10/2013 07:59, Peter Lieven ha scritto: > if a raw device like an iscsi target or host device is used > the current implementation makes a second call out to get > the block status of bs->file. > > Signed-off-by: Peter Lieven > --- > v5: add a generic get_lba_status function in the raw driver which > adds the BDRV_BLOCK_RAW flag. bdrv_co_get_block_status will > handle the callout to bs->file then. > > v4: use a flag to detect the raw driver instead of the strncmp > hack > > block.c | 4 ++++ > block/raw_bsd.c | 3 ++- > include/block/block.h | 4 ++++ > 3 files changed, 10 insertions(+), 1 deletion(-) > > diff --git a/block.c b/block.c > index 93e113a..38a589e 100644 > --- a/block.c > +++ b/block.c > @@ -3147,6 +3147,10 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs, > return ret; > } > > + if (ret & BDRV_BLOCK_RAW) { > + return bdrv_get_block_status(bs->file, sector_num, nb_sectors, pnum); Strictly speaking, this should probably do something like this: assert(ret & BDRV_BLOCK_OFFSET_VALID); return bdrv_get_block_status(bs->file, ret >> BDRV_SECTOR_BITS, nb_sectors, pnum); Or alternatively the raw driver should return just "BDRV_BLOCK_RAW". As a third option, the raw driver could also return not just BDRV_BLOCK_RAW and BDRV_BLOCK_OFFSET_VALID, but also BDRV_BLOCK_DATA (so that the answer makes some sense even without going down to bs->file). But I'll let the block maintainers decide what to do. Paolo > + } > + > if (!(ret & BDRV_BLOCK_DATA)) { > if (bdrv_has_zero_init(bs)) { > ret |= BDRV_BLOCK_ZERO; > diff --git a/block/raw_bsd.c b/block/raw_bsd.c > index d4ace60..308d605 100644 > --- a/block/raw_bsd.c > +++ b/block/raw_bsd.c > @@ -62,7 +62,8 @@ static int64_t coroutine_fn raw_co_get_block_status(BlockDriverState *bs, > int64_t sector_num, > int nb_sectors, int *pnum) > { > - return bdrv_get_block_status(bs->file, sector_num, nb_sectors, pnum); > + return BDRV_BLOCK_RAW | BDRV_BLOCK_OFFSET_VALID | > + (sector_num << BDRV_SECTOR_BITS); > } > > static int coroutine_fn raw_co_write_zeroes(BlockDriverState *bs, > diff --git a/include/block/block.h b/include/block/block.h > index f808550..003699e 100644 > --- a/include/block/block.h > +++ b/include/block/block.h > @@ -84,6 +84,9 @@ typedef struct BlockDevOps { > /* BDRV_BLOCK_DATA: data is read from bs->file or another file > * BDRV_BLOCK_ZERO: sectors read as zero > * BDRV_BLOCK_OFFSET_VALID: sector stored in bs->file as raw data > + * BDRV_BLOCK_RAW: used internally to indicate that the request > + * was answered by the raw driver and that one > + * should look in bs->file directly. > * > * If BDRV_BLOCK_OFFSET_VALID is set, bits 9-62 represent the offset in > * bs->file where sector data can be read from as raw data. > @@ -105,6 +108,7 @@ typedef struct BlockDevOps { > #define BDRV_BLOCK_DATA 1 > #define BDRV_BLOCK_ZERO 2 > #define BDRV_BLOCK_OFFSET_VALID 4 > +#define BDRV_BLOCK_RAW 8 > #define BDRV_BLOCK_OFFSET_MASK BDRV_SECTOR_MASK > > typedef enum { >