From decaeed7734bddc95e2c81858fbbec3e923310a1 Mon Sep 17 00:00:00 2001 From: Eric Blake Date: Fri, 15 Jul 2016 17:23:08 -0600 Subject: [PATCH] raw_bsd: Convert to byte-based interface Since the raw format driver is just passing things through, we can do byte-based read and write if the underlying protocol does likewise. There's one tricky part - if we probed the image format, we document that we restrict operations on the initial sector. It's easiest to keep this guarantee by enforcing read-modify-write on sub-sector operations (yes, this partially reverts commit ad82be2f). Signed-off-by: Eric Blake Message-id: 1468624988-423-20-git-send-email-eblake@redhat.com Signed-off-by: Stefan Hajnoczi --- block/raw_bsd.c | 45 ++++++++++++++++++++++++++------------------- 1 file changed, 26 insertions(+), 19 deletions(-) diff --git a/block/raw_bsd.c b/block/raw_bsd.c index 961aa1370a..588d4080f9 100644 --- a/block/raw_bsd.c +++ b/block/raw_bsd.c @@ -50,33 +50,30 @@ static int raw_reopen_prepare(BDRVReopenState *reopen_state, return 0; } -static int coroutine_fn raw_co_readv(BlockDriverState *bs, int64_t sector_num, - int nb_sectors, QEMUIOVector *qiov) +static int coroutine_fn raw_co_preadv(BlockDriverState *bs, uint64_t offset, + uint64_t bytes, QEMUIOVector *qiov, + int flags) { BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO); - return bdrv_co_readv(bs->file, sector_num, nb_sectors, qiov); + return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags); } -static int coroutine_fn -raw_co_writev_flags(BlockDriverState *bs, int64_t sector_num, int nb_sectors, - QEMUIOVector *qiov, int flags) +static int coroutine_fn raw_co_pwritev(BlockDriverState *bs, uint64_t offset, + uint64_t bytes, QEMUIOVector *qiov, + int flags) { void *buf = NULL; BlockDriver *drv; QEMUIOVector local_qiov; int ret; - if (bs->probed && sector_num == 0) { - /* As long as these conditions are true, we can't get partial writes to - * the probe buffer and can just directly check the request. */ + if (bs->probed && offset < BLOCK_PROBE_BUF_SIZE && bytes) { + /* Handling partial writes would be a pain - so we just + * require that guests have 512-byte request alignment if + * probing occurred */ QEMU_BUILD_BUG_ON(BLOCK_PROBE_BUF_SIZE != 512); QEMU_BUILD_BUG_ON(BDRV_SECTOR_SIZE != 512); - - if (nb_sectors == 0) { - /* qemu_iovec_to_buf() would fail, but we want to return success - * instead of -EINVAL in this case. */ - return 0; - } + assert(offset == 0 && bytes >= BLOCK_PROBE_BUF_SIZE); buf = qemu_try_blockalign(bs->file->bs, 512); if (!buf) { @@ -105,8 +102,7 @@ raw_co_writev_flags(BlockDriverState *bs, int64_t sector_num, int nb_sectors, } BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO); - ret = bdrv_co_pwritev(bs->file, sector_num * BDRV_SECTOR_SIZE, - nb_sectors * BDRV_SECTOR_SIZE, qiov, flags); + ret = bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags); fail: if (qiov == &local_qiov) { @@ -150,6 +146,16 @@ static int raw_get_info(BlockDriverState *bs, BlockDriverInfo *bdi) return bdrv_get_info(bs->file->bs, bdi); } +static void raw_refresh_limits(BlockDriverState *bs, Error **errp) +{ + if (bs->probed) { + /* To make it easier to protect the first sector, any probed + * image is restricted to read-modify-write on sub-sector + * operations. */ + bs->bl.request_alignment = BDRV_SECTOR_SIZE; + } +} + static int raw_truncate(BlockDriverState *bs, int64_t offset) { return bdrv_truncate(bs->file->bs, offset); @@ -240,8 +246,8 @@ BlockDriver bdrv_raw = { .bdrv_open = &raw_open, .bdrv_close = &raw_close, .bdrv_create = &raw_create, - .bdrv_co_readv = &raw_co_readv, - .bdrv_co_writev_flags = &raw_co_writev_flags, + .bdrv_co_preadv = &raw_co_preadv, + .bdrv_co_pwritev = &raw_co_pwritev, .bdrv_co_pwrite_zeroes = &raw_co_pwrite_zeroes, .bdrv_co_pdiscard = &raw_co_pdiscard, .bdrv_co_get_block_status = &raw_co_get_block_status, @@ -249,6 +255,7 @@ BlockDriver bdrv_raw = { .bdrv_getlength = &raw_getlength, .has_variable_length = true, .bdrv_get_info = &raw_get_info, + .bdrv_refresh_limits = &raw_refresh_limits, .bdrv_probe_blocksizes = &raw_probe_blocksizes, .bdrv_probe_geometry = &raw_probe_geometry, .bdrv_media_changed = &raw_media_changed, -- 2.11.4.GIT