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author | Kevin Wolf <kwolf@redhat.com> | 2016-06-03 16:17:28 +0200 |
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committer | Kevin Wolf <kwolf@redhat.com> | 2016-06-16 15:19:55 +0200 |
commit | 49c0752600d22606b411ace75b22e65398999d95 (patch) | |
tree | 0a33a23c892f5b2bee706834d346173c7b7184ba /block | |
parent | 244483e64ee726cc89a1e05bed2be0ed37071403 (diff) | |
download | qemu-49c0752600d22606b411ace75b22e65398999d95.zip qemu-49c0752600d22606b411ace75b22e65398999d95.tar.gz qemu-49c0752600d22606b411ace75b22e65398999d95.tar.bz2 |
block: Prepare bdrv_aligned_preadv() for byte-aligned requests
This patch makes bdrv_aligned_preadv() ready to accept byte-aligned
requests. Note that this doesn't mean that such requests are actually
made. The caller still ensures that all requests are aligned to at least
512 bytes.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'block')
-rw-r--r-- | block/io.c | 44 |
1 files changed, 20 insertions, 24 deletions
@@ -963,11 +963,9 @@ static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs, { int ret; - int64_t sector_num = offset >> BDRV_SECTOR_BITS; - unsigned int nb_sectors = bytes >> BDRV_SECTOR_BITS; - - assert((offset & (BDRV_SECTOR_SIZE - 1)) == 0); - assert((bytes & (BDRV_SECTOR_SIZE - 1)) == 0); + assert(is_power_of_2(align)); + assert((offset & (align - 1)) == 0); + assert((bytes & (align - 1)) == 0); assert(!qiov || bytes == qiov->size); assert((bs->open_flags & BDRV_O_NO_IO) == 0); assert(!(flags & ~BDRV_REQ_MASK)); @@ -987,9 +985,12 @@ static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs, } if (flags & BDRV_REQ_COPY_ON_READ) { + int64_t start_sector = offset >> BDRV_SECTOR_BITS; + int64_t end_sector = DIV_ROUND_UP(offset + bytes, BDRV_SECTOR_SIZE); + unsigned int nb_sectors = end_sector - start_sector; int pnum; - ret = bdrv_is_allocated(bs, sector_num, nb_sectors, &pnum); + ret = bdrv_is_allocated(bs, start_sector, nb_sectors, &pnum); if (ret < 0) { goto out; } @@ -1005,28 +1006,24 @@ static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs, ret = bdrv_driver_preadv(bs, offset, bytes, qiov, 0); } else { /* Read zeros after EOF */ - int64_t total_sectors, max_nb_sectors; + int64_t total_bytes, max_bytes; - total_sectors = bdrv_nb_sectors(bs); - if (total_sectors < 0) { - ret = total_sectors; + total_bytes = bdrv_getlength(bs); + if (total_bytes < 0) { + ret = total_bytes; goto out; } - max_nb_sectors = ROUND_UP(MAX(0, total_sectors - sector_num), - align >> BDRV_SECTOR_BITS); - if (nb_sectors < max_nb_sectors) { + max_bytes = ROUND_UP(MAX(0, total_bytes - offset), align); + if (bytes < max_bytes) { ret = bdrv_driver_preadv(bs, offset, bytes, qiov, 0); - } else if (max_nb_sectors > 0) { + } else if (max_bytes > 0) { QEMUIOVector local_qiov; qemu_iovec_init(&local_qiov, qiov->niov); - qemu_iovec_concat(&local_qiov, qiov, 0, - max_nb_sectors * BDRV_SECTOR_SIZE); + qemu_iovec_concat(&local_qiov, qiov, 0, max_bytes); - ret = bdrv_driver_preadv(bs, offset, - max_nb_sectors * BDRV_SECTOR_SIZE, - &local_qiov, 0); + ret = bdrv_driver_preadv(bs, offset, max_bytes, &local_qiov, 0); qemu_iovec_destroy(&local_qiov); } else { @@ -1034,11 +1031,10 @@ static int coroutine_fn bdrv_aligned_preadv(BlockDriverState *bs, } /* Reading beyond end of file is supposed to produce zeroes */ - if (ret == 0 && total_sectors < sector_num + nb_sectors) { - uint64_t offset = MAX(0, total_sectors - sector_num); - uint64_t bytes = (sector_num + nb_sectors - offset) * - BDRV_SECTOR_SIZE; - qemu_iovec_memset(qiov, offset * BDRV_SECTOR_SIZE, 0, bytes); + if (ret == 0 && total_bytes < offset + bytes) { + uint64_t zero_offset = MAX(0, total_bytes - offset); + uint64_t zero_bytes = offset + bytes - zero_offset; + qemu_iovec_memset(qiov, zero_offset, 0, zero_bytes); } } |