-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2 iQEtBAABCAAXBQJZVlttEBxmYW16QHJlZGhhdC5jb20ACgkQyjViTGqRccaSJQf/ aKBxpeES6l4zYoa09+x7eJwjQXj6RdIpUNL5N4a/dhUsVJ2keWo6lPcjC/kcbwPR TJ4zYplm+suVzbNZG4XJGXLryo6ODIaHhpa/Ctsf3i6vQkRipxManpTbqqnyjt/e fAnwdFu0dFKbnqJECujDQgaZo1qWLuyZP++ZFt2kiZgOX/OdHpnQPH2U4l+22Cp6 LB2FAFv0TwDjxmzM6EuOjsuLr9Rq3ckx7CVoyCnZuWkcaqn3/2cXhdNDErUB1nl7 Pa/N3khz6PJs1Q8/H3GPH+BJHfORLRFR6dZ/eD8JU6qqBJfguvkSmi9cQUlbVsko KEBqUmL+bKJaK257lkUkfg== =wO2z -----END PGP SIGNATURE----- Merge remote-tracking branch 'remotes/famz/tags/block-pull-request' into staging # gpg: Signature made Fri 30 Jun 2017 15:08:45 BST # gpg: using RSA key 0xCA35624C6A9171C6 # gpg: Good signature from "Fam Zheng <famz@redhat.com>" # gpg: WARNING: This key is not certified with a trusted signature! # gpg: There is no indication that the signature belongs to the owner. # Primary key fingerprint: 5003 7CB7 9706 0F76 F021 AD56 CA35 624C 6A91 71C6 * remotes/famz/tags/block-pull-request: block: Exploit BDRV_BLOCK_EOF for larger zero blocks block: Add BDRV_BLOCK_EOF to bdrv_get_block_status() Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Peter Maydell
commit
82d76dc7fc
42
block/io.c
42
block/io.c
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@ -1711,15 +1711,16 @@ typedef struct BdrvCoGetBlockStatusData {
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* Drivers not implementing the functionality are assumed to not support
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* backing files, hence all their sectors are reported as allocated.
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*
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* If 'sector_num' is beyond the end of the disk image the return value is 0
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* and 'pnum' is set to 0.
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* If 'sector_num' is beyond the end of the disk image the return value is
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* BDRV_BLOCK_EOF and 'pnum' is set to 0.
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*
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* 'pnum' is set to the number of sectors (including and immediately following
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* the specified sector) that are known to be in the same
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* allocated/unallocated state.
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*
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* 'nb_sectors' is the max value 'pnum' should be set to. If nb_sectors goes
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* beyond the end of the disk image it will be clamped.
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* beyond the end of the disk image it will be clamped; if 'pnum' is set to
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* the end of the image, then the returned value will include BDRV_BLOCK_EOF.
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*
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* If returned value is positive and BDRV_BLOCK_OFFSET_VALID bit is set, 'file'
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* points to the BDS which the sector range is allocated in.
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@ -1740,7 +1741,7 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
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if (sector_num >= total_sectors) {
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*pnum = 0;
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return 0;
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return BDRV_BLOCK_EOF;
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}
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n = total_sectors - sector_num;
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@ -1751,6 +1752,9 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
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if (!bs->drv->bdrv_co_get_block_status) {
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*pnum = nb_sectors;
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ret = BDRV_BLOCK_DATA | BDRV_BLOCK_ALLOCATED;
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if (sector_num + nb_sectors == total_sectors) {
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ret |= BDRV_BLOCK_EOF;
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}
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if (bs->drv->protocol_name) {
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ret |= BDRV_BLOCK_OFFSET_VALID | (sector_num * BDRV_SECTOR_SIZE);
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}
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@ -1799,10 +1803,13 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
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/* Ignore errors. This is just providing extra information, it
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* is useful but not necessary.
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*/
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if (!file_pnum) {
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/* !file_pnum indicates an offset at or beyond the EOF; it is
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* perfectly valid for the format block driver to point to such
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* offsets, so catch it and mark everything as zero */
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if (ret2 & BDRV_BLOCK_EOF &&
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(!file_pnum || ret2 & BDRV_BLOCK_ZERO)) {
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/*
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* It is valid for the format block driver to read
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* beyond the end of the underlying file's current
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* size; such areas read as zero.
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*/
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ret |= BDRV_BLOCK_ZERO;
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} else {
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/* Limit request to the range reported by the protocol driver */
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@ -1814,6 +1821,9 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
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out:
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bdrv_dec_in_flight(bs);
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if (ret >= 0 && sector_num + *pnum == total_sectors) {
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ret |= BDRV_BLOCK_EOF;
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}
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return ret;
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}
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@ -1826,16 +1836,30 @@ static int64_t coroutine_fn bdrv_co_get_block_status_above(BlockDriverState *bs,
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{
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BlockDriverState *p;
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int64_t ret = 0;
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bool first = true;
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assert(bs != base);
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for (p = bs; p != base; p = backing_bs(p)) {
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ret = bdrv_co_get_block_status(p, sector_num, nb_sectors, pnum, file);
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if (ret < 0 || ret & BDRV_BLOCK_ALLOCATED) {
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if (ret < 0) {
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break;
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}
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if (ret & BDRV_BLOCK_ZERO && ret & BDRV_BLOCK_EOF && !first) {
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/*
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* Reading beyond the end of the file continues to read
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* zeroes, but we can only widen the result to the
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* unallocated length we learned from an earlier
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* iteration.
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*/
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*pnum = nb_sectors;
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}
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if (ret & (BDRV_BLOCK_ZERO | BDRV_BLOCK_DATA)) {
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break;
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}
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/* [sector_num, pnum] unallocated on this layer, which could be only
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* the first part of [sector_num, nb_sectors]. */
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nb_sectors = MIN(nb_sectors, *pnum);
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first = false;
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}
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return ret;
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}
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@ -129,6 +129,7 @@ typedef struct HDGeometry {
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* BDRV_BLOCK_OFFSET_VALID: an associated offset exists for accessing raw data
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* BDRV_BLOCK_ALLOCATED: the content of the block is determined by this
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* layer (short for DATA || ZERO), set by block layer
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* BDRV_BLOCK_EOF: the returned pnum covers through end of file for this layer
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*
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* Internal flag:
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* BDRV_BLOCK_RAW: used internally to indicate that the request was
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@ -157,6 +158,7 @@ typedef struct HDGeometry {
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#define BDRV_BLOCK_OFFSET_VALID 0x04
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#define BDRV_BLOCK_RAW 0x08
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#define BDRV_BLOCK_ALLOCATED 0x10
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#define BDRV_BLOCK_EOF 0x20
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#define BDRV_BLOCK_OFFSET_MASK BDRV_SECTOR_MASK
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typedef QSIMPLEQ_HEAD(BlockReopenQueue, BlockReopenQueueEntry) BlockReopenQueue;
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@ -334,8 +334,6 @@ $QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
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$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
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# Repeat with backing file holding unallocated cluster.
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# TODO: Note that this forces an allocation, because we aren't yet able to
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# quickly detect that reads beyond EOF of the backing file are always zero
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CLUSTER_SIZE=2048 TEST_IMG="$TEST_IMG.base" _make_test_img $((size + 1024))
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# Write at the front: sector-wise, the request is:
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@ -371,8 +369,6 @@ $QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
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$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
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# Repeat with backing file holding zero'd cluster
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# TODO: Note that this forces an allocation, because we aren't yet able to
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# quickly detect that reads beyond EOF of the backing file are always zero
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$QEMU_IO -c "write -z $size 512" "$TEST_IMG.base" | _filter_qemu_io
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# Write at the front: sector-wise, the request is:
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@ -310,19 +310,19 @@ wrote 512/512 bytes at offset 134217728
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512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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2048/2048 bytes allocated at offset 128 MiB
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[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false},
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{ "start": 134217728, "length": 2048, "depth": 0, "zero": false, "data": true, "offset": OFFSET}]
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{ "start": 134217728, "length": 2048, "depth": 0, "zero": true, "data": false}]
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Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base
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wrote 512/512 bytes at offset 134219264
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512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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2048/2048 bytes allocated at offset 128 MiB
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[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false},
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{ "start": 134217728, "length": 2048, "depth": 0, "zero": false, "data": true, "offset": OFFSET}]
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{ "start": 134217728, "length": 2048, "depth": 0, "zero": true, "data": false}]
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Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base
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wrote 1024/1024 bytes at offset 134218240
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1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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2048/2048 bytes allocated at offset 128 MiB
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[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false},
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{ "start": 134217728, "length": 2048, "depth": 0, "zero": false, "data": true, "offset": OFFSET}]
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{ "start": 134217728, "length": 2048, "depth": 0, "zero": true, "data": false}]
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Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base
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wrote 2048/2048 bytes at offset 134217728
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2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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@ -336,19 +336,19 @@ wrote 512/512 bytes at offset 134217728
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512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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2048/2048 bytes allocated at offset 128 MiB
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[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false},
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{ "start": 134217728, "length": 2048, "depth": 0, "zero": false, "data": true, "offset": OFFSET}]
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{ "start": 134217728, "length": 2048, "depth": 0, "zero": true, "data": false}]
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Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base
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wrote 512/512 bytes at offset 134219264
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512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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2048/2048 bytes allocated at offset 128 MiB
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[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false},
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{ "start": 134217728, "length": 2048, "depth": 0, "zero": false, "data": true, "offset": OFFSET}]
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{ "start": 134217728, "length": 2048, "depth": 0, "zero": true, "data": false}]
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Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base
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wrote 1024/1024 bytes at offset 134218240
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1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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2048/2048 bytes allocated at offset 128 MiB
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[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false},
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{ "start": 134217728, "length": 2048, "depth": 0, "zero": false, "data": true, "offset": OFFSET}]
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{ "start": 134217728, "length": 2048, "depth": 0, "zero": true, "data": false}]
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Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base
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wrote 2048/2048 bytes at offset 134217728
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2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
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