From d5b3c858d7d2d96cf89495c95c2f07eb246b6730 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Mon, 2 Dec 2013 15:07:48 +0100 Subject: [PATCH 11/37] block: Introduce bdrv_aligned_preadv() Message-id: <1392117622-28812-12-git-send-email-kwolf@redhat.com> Patchwork-id: 57176 O-Subject: [RHEL-7.0 qemu-kvm PATCH v2 11/37] block: Introduce bdrv_aligned_preadv() Bugzilla: 748906 RH-Acked-by: Laszlo Ersek RH-Acked-by: Stefan Hajnoczi RH-Acked-by: Max Reitz This separates the part of bdrv_co_do_readv() that needs to happen before the request is modified to match the backend alignment, and a part that needs to be executed afterwards and passes the request to the BlockDriver. Signed-off-by: Kevin Wolf Reviewed-by: Wenchao Xia Reviewed-by: Max Reitz (cherry picked from commit d0c7f642f5eb2cb21d0c3acf766cb375eaaf4666) Conflicts: block.c Conflicts because RHEL 7 still has the old I/O throttling code. Signed-off-by: Kevin Wolf --- block.c | 59 ++++++++++++++++++++++++++++++++++++++++++----------------- 1 file changed, 42 insertions(+), 17 deletions(-) --- block.c | 59 ++++++++++++++++++++++++++++++++++++++++++----------------- 1 files changed, 42 insertions(+), 17 deletions(-) diff --git a/block.c b/block.c index 40a4a34..1787ab0 100644 --- a/block.c +++ b/block.c @@ -2723,31 +2723,24 @@ err: } /* - * Handle a read request in coroutine context + * Forwards an already correctly aligned request to the BlockDriver. This + * handles copy on read and zeroing after EOF; any other features must be + * implemented by the caller. */ -static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs, - int64_t sector_num, int nb_sectors, QEMUIOVector *qiov, - BdrvRequestFlags flags) +static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs, + int64_t offset, unsigned int bytes, QEMUIOVector *qiov, int flags) { BlockDriver *drv = bs->drv; BdrvTrackedRequest req; int ret; - if (!drv) { - return -ENOMEDIUM; - } - if (bdrv_check_request(bs, sector_num, nb_sectors)) { - return -EIO; - } + int64_t sector_num = offset >> BDRV_SECTOR_BITS; + unsigned int nb_sectors = bytes >> BDRV_SECTOR_BITS; - /* throttling disk read I/O */ - if (bs->io_limits_enabled) { - bdrv_io_limits_intercept(bs, false, nb_sectors); - } + assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0); + assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0); - if (bs->copy_on_read) { - flags |= BDRV_REQ_COPY_ON_READ; - } + /* Handle Copy on Read and associated serialisation */ if (flags & BDRV_REQ_COPY_ON_READ) { bs->copy_on_read_in_flight++; } @@ -2772,6 +2765,7 @@ static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs, } } + /* Forward the request to the BlockDriver */ if (!(bs->zero_beyond_eof && bs->growable)) { ret = drv->bdrv_co_readv(bs, sector_num, nb_sectors, qiov); } else { @@ -2812,6 +2806,37 @@ out: return ret; } +/* + * Handle a read request in coroutine context + */ +static int coroutine_fn bdrv_co_do_readv(BlockDriverState *bs, + int64_t sector_num, int nb_sectors, QEMUIOVector *qiov, + BdrvRequestFlags flags) +{ + BlockDriver *drv = bs->drv; + int ret; + + if (!drv) { + return -ENOMEDIUM; + } + if (bdrv_check_request(bs, sector_num, nb_sectors)) { + return -EIO; + } + + if (bs->copy_on_read) { + flags |= BDRV_REQ_COPY_ON_READ; + } + + /* throttling disk I/O */ + if (bs->io_limits_enabled) { + bdrv_io_limits_intercept(bs, false, nb_sectors); + } + + ret = bdrv_aligned_preadv(bs, sector_num << BDRV_SECTOR_BITS, + nb_sectors << BDRV_SECTOR_BITS, qiov, flags); + return ret; +} + int coroutine_fn bdrv_co_readv(BlockDriverState *bs, int64_t sector_num, int nb_sectors, QEMUIOVector *qiov) { -- 1.7.1