From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:58057) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SfY7S-0004Mi-7C for qemu-devel@nongnu.org; Fri, 15 Jun 2012 11:07:29 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SfY7N-00058R-AI for qemu-devel@nongnu.org; Fri, 15 Jun 2012 11:07:25 -0400 Received: from mail-pb0-f45.google.com ([209.85.160.45]:47190) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SfY7M-0004gs-Rs for qemu-devel@nongnu.org; Fri, 15 Jun 2012 11:07:21 -0400 Received: by mail-pb0-f45.google.com with SMTP id ro12so5648793pbb.4 for ; Fri, 15 Jun 2012 08:07:20 -0700 (PDT) Sender: Paolo Bonzini From: Paolo Bonzini Date: Fri, 15 Jun 2012 17:05:44 +0200 Message-Id: <1339772759-31004-22-git-send-email-pbonzini@redhat.com> In-Reply-To: <1339772759-31004-1-git-send-email-pbonzini@redhat.com> References: <1339772759-31004-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [RFC PATCH 21/36] block: introduce new dirty bitmap functionality List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: kwolf@redhat.com, stefanha@linux.vnet.ibm.com, lcapitulino@redhat.com Assert that write_compressed is never used with the dirty bitmap. Setting the bits early is wrong, because a coroutine might concurrently examine them and copy incomplete data from the source. Signed-off-by: Paolo Bonzini --- block.c | 51 +++++++++++++++++++++++++++++++++++++++++++++------ block.h | 5 +++-- 2 files changed, 48 insertions(+), 8 deletions(-) diff --git a/block.c b/block.c index f1afdd6..dbb9041 100644 --- a/block.c +++ b/block.c @@ -2021,7 +2021,7 @@ static int coroutine_fn bdrv_co_do_writev(BlockDriverState *bs, } if (bs->dirty_bitmap) { - set_dirty_bitmap(bs, sector_num, nb_sectors, 1); + bdrv_set_dirty(bs, sector_num, nb_sectors); } if (bs->wr_highest_sector < sector_num + nb_sectors - 1) { @@ -2838,9 +2838,7 @@ int bdrv_write_compressed(BlockDriverState *bs, int64_t sector_num, if (bdrv_check_request(bs, sector_num, nb_sectors)) return -EIO; - if (bs->dirty_bitmap) { - set_dirty_bitmap(bs, sector_num, nb_sectors, 1); - } + assert(!bs->dirty_bitmap); return drv->bdrv_write_compressed(bs, sector_num, buf, nb_sectors); } @@ -4069,13 +4067,54 @@ int bdrv_get_dirty(BlockDriverState *bs, int64_t sector) if (bs->dirty_bitmap && (sector << BDRV_SECTOR_BITS) < bdrv_getlength(bs)) { - return !!(bs->dirty_bitmap[chunk / (sizeof(unsigned long) * 8)] & - (1UL << (chunk % (sizeof(unsigned long) * 8)))); + return !!(bs->dirty_bitmap[chunk / BITS_PER_LONG] & + (1UL << (chunk % BITS_PER_LONG))); } else { return 0; } } +int64_t bdrv_get_next_dirty(BlockDriverState *bs, int64_t sector) +{ + int64_t chunk; + int bit, elem; + + /* Avoid an infinite loop. */ + assert(bs->dirty_count > 0); + + sector = (sector | (BDRV_SECTORS_PER_DIRTY_CHUNK - 1)) + 1; + chunk = sector / (int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK; + + QEMU_BUILD_BUG_ON(sizeof(bs->dirty_bitmap[0]) * 8 != BITS_PER_LONG); + elem = chunk / BITS_PER_LONG; + bit = chunk % BITS_PER_LONG; + for (;;) { + if (sector >= bs->total_sectors) { + sector = 0; + bit = elem = 0; + } + if (bit == 0 && bs->dirty_bitmap[elem] == 0) { + sector += BDRV_SECTORS_PER_DIRTY_CHUNK * BITS_PER_LONG; + elem++; + } else { + if (bs->dirty_bitmap[elem] & (1UL << bit)) { + return sector; + } + sector += BDRV_SECTORS_PER_DIRTY_CHUNK; + if (++bit == BITS_PER_LONG) { + bit = 0; + elem++; + } + } + } +} + +void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector, + int nr_sectors) +{ + set_dirty_bitmap(bs, cur_sector, nr_sectors, 1); +} + void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector, int nr_sectors) { diff --git a/block.h b/block.h index 1e13469..c13d779 100644 --- a/block.h +++ b/block.h @@ -356,8 +356,9 @@ void *qemu_blockalign(BlockDriverState *bs, size_t size); void bdrv_set_dirty_tracking(BlockDriverState *bs, int enable); int bdrv_get_dirty(BlockDriverState *bs, int64_t sector); -void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector, - int nr_sectors); +void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector, int nr_sectors); +void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector, int nr_sectors); +int64_t bdrv_get_next_dirty(BlockDriverState *bs, int64_t sector); int64_t bdrv_get_dirty_count(BlockDriverState *bs); void bdrv_enable_copy_on_read(BlockDriverState *bs); -- 1.7.10.2