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Re: [Qemu-devel] [PATCH v8 1/4] quorum: Add the rewrite-corrupted parame
From: |
Benoît Canet |
Subject: |
Re: [Qemu-devel] [PATCH v8 1/4] quorum: Add the rewrite-corrupted parameter to quorum. |
Date: |
Tue, 10 Jun 2014 09:25:04 +0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
The Tuesday 10 Jun 2014 à 09:21:43 (+0200), Benoît Canet wrote :
Oh i again submitted a commit subject ending with a dot I will remove theses.
> On read operations when this parameter is set and some replicas are corrupted
> while quorum can be reached quorum will proceed to rewrite the correct version
> of the data to fix the corrupted replicas.
>
> This will shine with SSD where the FTL will remap the same block at another
> place on rewrite.
>
> Signed-off-by: Benoit Canet <address@hidden>
> ---
> block/quorum.c | 97
> +++++++++++++++++++++++++++++++++++++++++++---
> qapi/block-core.json | 5 ++-
> tests/qemu-iotests/081 | 15 ++++++-
> tests/qemu-iotests/081.out | 10 +++++
> 4 files changed, 119 insertions(+), 8 deletions(-)
>
> diff --git a/block/quorum.c b/block/quorum.c
> index 426077a..1a7a01e 100644
> --- a/block/quorum.c
> +++ b/block/quorum.c
> @@ -22,6 +22,7 @@
>
> #define QUORUM_OPT_VOTE_THRESHOLD "vote-threshold"
> #define QUORUM_OPT_BLKVERIFY "blkverify"
> +#define QUORUM_OPT_REWRITE "rewrite-corrupted"
>
> /* This union holds a vote hash value */
> typedef union QuorumVoteValue {
> @@ -69,6 +70,9 @@ typedef struct BDRVQuorumState {
> * It is useful to debug other block drivers by
> * comparing them with a reference one.
> */
> + bool rewrite_corrupted;/* true if the driver must rewrite-on-read
> corrupted
> + * block if Quorum is reached.
> + */
> } BDRVQuorumState;
>
> typedef struct QuorumAIOCB QuorumAIOCB;
> @@ -104,13 +108,17 @@ struct QuorumAIOCB {
> int count; /* number of completed AIOCB */
> int success_count; /* number of successfully completed AIOCB */
>
> + int rewrite_count; /* number of replica to rewrite: count down
> to
> + * zero once writes are fired
> + */
> +
> QuorumVotes votes;
>
> bool is_read;
> int vote_ret;
> };
>
> -static void quorum_vote(QuorumAIOCB *acb);
> +static bool quorum_vote(QuorumAIOCB *acb);
>
> static void quorum_aio_cancel(BlockDriverAIOCB *blockacb)
> {
> @@ -182,6 +190,7 @@ static QuorumAIOCB *quorum_aio_get(BDRVQuorumState *s,
> acb->qcrs = g_new0(QuorumChildRequest, s->num_children);
> acb->count = 0;
> acb->success_count = 0;
> + acb->rewrite_count = 0;
> acb->votes.compare = quorum_sha256_compare;
> QLIST_INIT(&acb->votes.vote_list);
> acb->is_read = false;
> @@ -241,11 +250,27 @@ static bool quorum_has_too_much_io_failed(QuorumAIOCB
> *acb)
> return false;
> }
>
> +static void quorum_rewrite_aio_cb(void *opaque, int ret)
> +{
> + QuorumAIOCB *acb = opaque;
> +
> + /* one less rewrite to do */
> + acb->rewrite_count--;
> +
> + /* wait until all rewrite callbacks have completed */
> + if (acb->rewrite_count) {
> + return;
> + }
> +
> + quorum_aio_finalize(acb);
> +}
> +
> static void quorum_aio_cb(void *opaque, int ret)
> {
> QuorumChildRequest *sacb = opaque;
> QuorumAIOCB *acb = sacb->parent;
> BDRVQuorumState *s = acb->common.bs->opaque;
> + bool rewrite = false;
>
> sacb->ret = ret;
> acb->count++;
> @@ -262,12 +287,15 @@ static void quorum_aio_cb(void *opaque, int ret)
>
> /* Do the vote on read */
> if (acb->is_read) {
> - quorum_vote(acb);
> + rewrite = quorum_vote(acb);
> } else {
> quorum_has_too_much_io_failed(acb);
> }
>
> - quorum_aio_finalize(acb);
> + /* if no rewrite is done the code will finish right away */
> + if (!rewrite) {
> + quorum_aio_finalize(acb);
> + }
> }
>
> static void quorum_report_bad_versions(BDRVQuorumState *s,
> @@ -287,6 +315,43 @@ static void quorum_report_bad_versions(BDRVQuorumState
> *s,
> }
> }
>
> +static bool quorum_rewrite_bad_versions(BDRVQuorumState *s, QuorumAIOCB *acb,
> + QuorumVoteValue *value)
> +{
> + QuorumVoteVersion *version;
> + QuorumVoteItem *item;
> + int count = 0;
> +
> + /* first count the number of bad versions: done first to avoid
> concurrency
> + * issues.
> + */
> + QLIST_FOREACH(version, &acb->votes.vote_list, next) {
> + if (acb->votes.compare(&version->value, value)) {
> + continue;
> + }
> + QLIST_FOREACH(item, &version->items, next) {
> + count++;
> + }
> + }
> +
> + /* quorum_rewrite_aio_cb will count down this to zero */
> + acb->rewrite_count = count;
> +
> + /* now fire the correcting rewrites */
> + QLIST_FOREACH(version, &acb->votes.vote_list, next) {
> + if (acb->votes.compare(&version->value, value)) {
> + continue;
> + }
> + QLIST_FOREACH(item, &version->items, next) {
> + bdrv_aio_writev(s->bs[item->index], acb->sector_num, acb->qiov,
> + acb->nb_sectors, quorum_rewrite_aio_cb, acb);
> + }
> + }
> +
> + /* return true if any rewrite is done else false */
> + return count;
> +}
> +
> static void quorum_copy_qiov(QEMUIOVector *dest, QEMUIOVector *source)
> {
> int i;
> @@ -477,16 +542,17 @@ static int quorum_vote_error(QuorumAIOCB *acb)
> return ret;
> }
>
> -static void quorum_vote(QuorumAIOCB *acb)
> +static bool quorum_vote(QuorumAIOCB *acb)
> {
> bool quorum = true;
> + bool rewrite = false;
> int i, j, ret;
> QuorumVoteValue hash;
> BDRVQuorumState *s = acb->common.bs->opaque;
> QuorumVoteVersion *winner;
>
> if (quorum_has_too_much_io_failed(acb)) {
> - return;
> + return false;
> }
>
> /* get the index of the first successful read */
> @@ -514,7 +580,7 @@ static void quorum_vote(QuorumAIOCB *acb)
> /* Every successful read agrees */
> if (quorum) {
> quorum_copy_qiov(acb->qiov, &acb->qcrs[i].qiov);
> - return;
> + return false;
> }
>
> /* compute hashes for each successful read, also store indexes */
> @@ -547,9 +613,15 @@ static void quorum_vote(QuorumAIOCB *acb)
> /* some versions are bad print them */
> quorum_report_bad_versions(s, acb, &winner->value);
>
> + /* corruption correction is enabled */
> + if (s->rewrite_corrupted) {
> + rewrite = quorum_rewrite_bad_versions(s, acb, &winner->value);
> + }
> +
> free_exit:
> /* free lists */
> quorum_free_vote_list(&acb->votes);
> + return rewrite;
> }
>
> static BlockDriverAIOCB *quorum_aio_readv(BlockDriverState *bs,
> @@ -714,6 +786,11 @@ static QemuOptsList quorum_runtime_opts = {
> .type = QEMU_OPT_BOOL,
> .help = "Trigger block verify mode if set",
> },
> + {
> + .name = QUORUM_OPT_REWRITE,
> + .type = QEMU_OPT_BOOL,
> + .help = "Rewrite corrupted block on read quorum",
> + },
> { /* end of list */ }
> },
> };
> @@ -775,6 +852,14 @@ static int quorum_open(BlockDriverState *bs, QDict
> *options, int flags,
> "and using two files with vote_threshold=2\n");
> }
>
> + s->rewrite_corrupted = qemu_opt_get_bool(opts, QUORUM_OPT_REWRITE,
> false);
> + if (s->rewrite_corrupted && s->is_blkverify) {
> + error_setg(&local_err,
> + "rewrite-corrupted=on cannot be used with blkverify=on");
> + ret = -EINVAL;
> + goto exit;
> + }
> +
> /* allocate the children BlockDriverState array */
> s->bs = g_new0(BlockDriverState *, s->num_children);
> opened = g_new0(bool, s->num_children);
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index 33bd93f..eec881b 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -1333,12 +1333,15 @@
> #
> # @vote-threshold: the vote limit under which a read will fail
> #
> +# @rewrite-corrupted: #optional rewrite corrupted data when quorum is reached
> +# (Since 2.1)
> +#
> # Since: 2.0
> ##
> { 'type': 'BlockdevOptionsQuorum',
> 'data': { '*blkverify': 'bool',
> 'children': [ 'BlockdevRef' ],
> - 'vote-threshold': 'int' } }
> + 'vote-threshold': 'int', '*rewrite-corrupted': 'bool' } }
>
> ##
> # @BlockdevOptions
> diff --git a/tests/qemu-iotests/081 b/tests/qemu-iotests/081
> index b512d00..7ae4be2 100755
> --- a/tests/qemu-iotests/081
> +++ b/tests/qemu-iotests/081
> @@ -134,15 +134,28 @@ run_qemu -drive
> "file=$TEST_DIR/2.raw,format=$IMGFMT,if=none,id=drive2" <<EOF
> EOF
>
> echo
> +echo "== using quorum rewrite corrupted mode =="
> +
> +quorum="$quorum,file.rewrite-corrupted=on"
> +
> +$QEMU_IO -c "open -o $quorum" -c "read -P 0x32 0 $size" | _filter_qemu_io
> +
> +echo
> +echo "== checking that quorum has corrected the corrupted file =="
> +
> +$QEMU_IO -c "read -P 0x32 0 $size" "$TEST_DIR/2.raw" | _filter_qemu_io
> +
> +echo
> echo "== breaking quorum =="
>
> $QEMU_IO -c "write -P 0x41 0 $size" "$TEST_DIR/1.raw" | _filter_qemu_io
> +$QEMU_IO -c "write -P 0x42 0 $size" "$TEST_DIR/2.raw" | _filter_qemu_io
> +
> echo
> echo "== checking that quorum is broken =="
>
> $QEMU_IO -c "open -o $quorum" -c "read -P 0x32 0 $size" | _filter_qemu_io
>
> -
> # success, all done
> echo "*** done"
> rm -f $seq.full
> diff --git a/tests/qemu-iotests/081.out b/tests/qemu-iotests/081.out
> index 84aeb0c..1629d2a 100644
> --- a/tests/qemu-iotests/081.out
> +++ b/tests/qemu-iotests/081.out
> @@ -40,9 +40,19 @@ read 10485760/10485760 bytes at offset 0
> {"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP}, "event":
> "DEVICE_TRAY_MOVED", "data": {"device": "floppy0", "tray-open": true}}
>
>
> +== using quorum rewrite corrupted mode ==
> +read 10485760/10485760 bytes at offset 0
> +10 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
> +
> +== checking that quorum has corrected the corrupted file ==
> +read 10485760/10485760 bytes at offset 0
> +10 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
> +
> == breaking quorum ==
> wrote 10485760/10485760 bytes at offset 0
> 10 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
> +wrote 10485760/10485760 bytes at offset 0
> +10 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
>
> == checking that quorum is broken ==
> qemu-io: can't open device (null): Could not read image for determining its
> format: Input/output error
> --
> 1.9.1
>