Le Friday 08 Feb 2013 à 13:07:03 (+0100), Kevin Wolf a écrit : > Am 28.01.2013 18:07, schrieb Benoît Canet: > > Use gnutls's SHA-256 to compare versions. > > > > Signed-off-by: Benoit Canet <ben...@irqsave.net> > > --- > > block/quorum.c | 303 > > +++++++++++++++++++++++++++++++++++++++++++++++++++++++- > > configure | 22 ++++ > > 2 files changed, 324 insertions(+), 1 deletion(-) > > > > diff --git a/block/quorum.c b/block/quorum.c > > index e3c6aad..4c552e4 100644 > > --- a/block/quorum.c > > +++ b/block/quorum.c > > @@ -13,8 +13,30 @@ > > * See the COPYING file in the top-level directory. > > */ > > > > +#include <gnutls/gnutls.h> > > +#include <gnutls/crypto.h> > > #include "block/block_int.h" > > > > +#define HASH_LENGTH 32 > > + > > +typedef union QuorumVoteValue { > > + char h[HASH_LENGTH]; /* SHA-256 hash */ > > + unsigned long l; /* simpler hash */ > > +} QuorumVoteValue; > > + > > +typedef struct QuorumVoteItem { > > + int index; > > + QLIST_ENTRY(QuorumVoteItem) next; > > +} QuorumVoteItem; > > + > > +typedef struct QuorumVoteVersion { > > + QuorumVoteValue value; > > + int index; > > + int vote_count; > > + QLIST_HEAD(, QuorumVoteItem) items; > > + QLIST_ENTRY(QuorumVoteVersion) next; > > +} QuorumVoteVersion; > > I wonder if it wouldn't become simpler if you used arrays instead of > lists. We know that s->total is the upper limit for entries. > > > + > > typedef struct { > > BlockDriverState **bs; > > unsigned long long threshold; > > @@ -32,6 +54,11 @@ typedef struct QuorumSingleAIOCB { > > QuorumAIOCB *parent; > > } QuorumSingleAIOCB; > > > > +typedef struct QuorumVotes { > > + QLIST_HEAD(, QuorumVoteVersion) vote_list; > > + int (*compare)(QuorumVoteValue *a, QuorumVoteValue *b); > > +} QuorumVotes; > > Can this be directly embedded into QuorumAIOCB? > > compare is always quorum_sha256_compare, so why even have a field? We > can still introduce it once we add different options. > > > + > > struct QuorumAIOCB { > > BlockDriverAIOCB common; > > BDRVQuorumState *bqs; > > @@ -48,6 +75,8 @@ struct QuorumAIOCB { > > int success_count; /* number of successfully completed AIOCB > > */ > > bool *finished; /* completion signal for cancel */ > > > > + QuorumVotes votes; > > + > > void (*vote)(QuorumAIOCB *acb); > > int vote_ret; > > }; > > @@ -84,6 +113,11 @@ static void quorum_aio_bh(void *opaque) > > } > > > > qemu_bh_delete(acb->bh); > > + > > + if (acb->vote_ret) { > > + ret = acb->vote_ret; > > + } > > + > > acb->common.cb(acb->common.opaque, ret); > > if (acb->finished) { > > *acb->finished = true; > > @@ -95,6 +129,11 @@ static void quorum_aio_bh(void *opaque) > > qemu_aio_release(acb); > > } > > > > +static int quorum_sha256_compare(QuorumVoteValue *a, QuorumVoteValue *b) > > +{ > > + return memcmp(a, b, HASH_LENGTH); > > +} > > Comparing a.h and b.h would be cleaner. > > > + > > static QuorumAIOCB *quorum_aio_get(BDRVQuorumState *s, > > BlockDriverState *bs, > > QEMUIOVector *qiov, > > @@ -118,6 +157,8 @@ static QuorumAIOCB *quorum_aio_get(BDRVQuorumState *s, > > acb->vote = NULL; > > acb->vote_ret = 0; > > acb->finished = NULL; > > + acb->votes.compare = quorum_sha256_compare; > > + QLIST_INIT(&acb->votes.vote_list); > > > > for (i = 0; i < s->total; i++) { > > acb->aios[i].buf = NULL; > > @@ -145,10 +186,268 @@ static void quorum_aio_cb(void *opaque, int ret) > > return; > > } > > > > + /* Do the vote */ > > + if (acb->vote) { > > + acb->vote(acb); > > + } > > This is NULL for all writes and quorum_vote for all reads. Is there any > chance that more options will be introduced? If not, why not have a bool > is_read and directly call the function here? > > > + > > acb->bh = qemu_bh_new(quorum_aio_bh, acb); > > qemu_bh_schedule(acb->bh); > > } > > > > +static void quorum_print_bad(QuorumAIOCB *acb, const char *filename) > > +{ > > + fprintf(stderr, "quorum: corrected error in quorum file %s: > > sector_num=%" > > + PRId64 " nb_sectors=%i\n", filename, acb->sector_num, > > + acb->nb_sectors); > > +} > > + > > +static void quorum_print_failure(QuorumAIOCB *acb) > > +{ > > + fprintf(stderr, "quorum: failure sector_num=%" PRId64 " > > nb_sectors=%i\n", > > + acb->sector_num, acb->nb_sectors); > > +} > > + > > +static void quorum_print_bad_versions(QuorumAIOCB *acb, > > + QuorumVoteValue *value) > > +{ > > + QuorumVoteVersion *version; > > + QuorumVoteItem *item; > > + BDRVQuorumState *s = acb->bqs; > > + > > + QLIST_FOREACH(version, &acb->votes.vote_list, next) { > > + if (!acb->votes.compare(&version->value, value)) { > > + continue; > > + } > > + QLIST_FOREACH(item, &version->items, next) { > > + quorum_print_bad(acb, s->filenames[item->index]); > > + } > > + } > > +} > > + > > +static void quorum_copy_qiov(QEMUIOVector *dest, QEMUIOVector *source) > > +{ > > + int i; > > + assert(dest->niov == source->niov); > > + assert(dest->size == source->size); > > + for (i = 0; i < source->niov; i++) { > > + assert(dest->iov[i].iov_len == source->iov[i].iov_len); > > + memcpy(dest->iov[i].iov_base, > > + source->iov[i].iov_base, > > + source->iov[i].iov_len); > > + } > > +} > > + > > +static void quorum_count_vote(QuorumVotes *votes, > > + QuorumVoteValue *value, > > + int index) > > +{ > > + QuorumVoteVersion *v = NULL, *version = NULL; > > + QuorumVoteItem *item; > > + > > + /* look if we have something with this hash */ > > + QLIST_FOREACH(v, &votes->vote_list, next) { > > + if (!votes->compare(&v->value, value)) { > > + version = v; > > + break; > > + } > > + } > > + > > + /* It's a version not yet in the list add it */ > > + if (!version) { > > + version = g_new0(QuorumVoteVersion, 1); > > + QLIST_INIT(&version->items); > > + memcpy(&version->value, value, sizeof(version->value)); > > + version->index = index; > > + version->vote_count = 0; > > + QLIST_INSERT_HEAD(&votes->vote_list, version, next); > > + } > > + > > + version->vote_count++; > > + > > + item = g_new0(QuorumVoteItem, 1); > > + item->index = index; > > + QLIST_INSERT_HEAD(&version->items, item, next); > > +} > > + > > +static void quorum_free_vote_list(QuorumVotes *votes) > > +{ > > + QuorumVoteVersion *version, *next_version; > > + QuorumVoteItem *item, *next_item; > > + > > + QLIST_FOREACH_SAFE(version, &votes->vote_list, next, next_version) { > > + QLIST_REMOVE(version, next); > > + QLIST_FOREACH_SAFE(item, &version->items, next, next_item) { > > + QLIST_REMOVE(item, next); > > + g_free(item); > > + } > > + g_free(version); > > + } > > +} > > + > > +static int quorum_compute_hash(QuorumAIOCB *acb, int i, QuorumVoteValue > > *hash) > > +{ > > + int j, ret; > > + gnutls_hash_hd_t dig; > > + QEMUIOVector *qiov = &acb->aios[i].qiov; > > + > > + ret = gnutls_hash_init(&dig, GNUTLS_DIG_SHA256); > > + > > + if (ret < 0) { > > + return ret; > > + } > > + > > + for (j = 0; j < qiov->niov; j++) { > > + ret = gnutls_hash(dig, qiov->iov[j].iov_base, > > qiov->iov[j].iov_len); > > + if (ret < 0) { > > + return ret; > > I have no clue about this lib, but sure that you don't need to call deinit? > > > + } > > + } > > + > > + gnutls_hash_deinit(dig, (void *) hash); > > + > > + return 0; > > +} > > + > > +static QuorumVoteVersion *quorum_get_vote_winner(QuorumVotes *votes) > > +{ > > + int i = 0; > > + QuorumVoteVersion *candidate, *winner = NULL; > > + > > + QLIST_FOREACH(candidate, &votes->vote_list, next) { > > + if (candidate->vote_count > i) { > > + i = candidate->vote_count; > > + winner = candidate; > > + } > > + } > > + > > + return winner; > > +} > > + > > +static bool quorum_iovec_compare(QEMUIOVector *a, QEMUIOVector *b) > > +{ > > + int i; > > + int result; > > + > > + assert(a->niov == b->niov); > > + for (i = 0; i < a->niov; i++) { > > + assert(a->iov[i].iov_len == b->iov[i].iov_len); > > + result = memcmp(a->iov[i].iov_base, > > + b->iov[i].iov_base, > > + a->iov[i].iov_len); > > + if (result) { > > + return false; > > + } > > + } > > + > > + return true; > > +} > > qemu_iovec_compare() seems to do exactly the same, except that this > doesn't return the offset of the first difference. > > Why is it a good idea to duplicate the code?
Quorum need speed: qemu_iovec_compare will do byte level comparison whereas memcmp will use SSE on large block. > > > + > > +static void GCC_FMT_ATTR(2, 3) quorum_err(QuorumAIOCB *acb, > > + const char *fmt, ...) > > +{ > > + va_list ap; > > + > > + va_start(ap, fmt); > > + fprintf(stderr, "quorum: sector_num=%" PRId64 " nb_sectors=%d ", > > + acb->sector_num, acb->nb_sectors); > > + vfprintf(stderr, fmt, ap); > > + fprintf(stderr, "\n"); > > + va_end(ap); > > + exit(1); > > +} > > + > > +static bool quorum_compare(QuorumAIOCB *acb, > > + QEMUIOVector *a, > > + QEMUIOVector *b) > > +{ > > + BDRVQuorumState *s = acb->bqs; > > + bool blkverify = false; > > + ssize_t offset; > > + > > + if (s->total == 2 && s->threshold == 2) { > > + blkverify = true; > > + } > > + > > + if (blkverify) { > > + offset = qemu_iovec_compare(a, b); > > + if (offset != -1) { > > + quorum_err(acb, "contents mismatch in sector %" PRId64, > > + acb->sector_num + > > + (uint64_t)(offset / BDRV_SECTOR_SIZE)); > > + } > > + return true; > > + } > > wtf is happening here? Why an uncommented special case for two images > that results in an entirely different behaviour? Why split the if block > and introduce a useless blkverify variable? > > > + > > + return quorum_iovec_compare(a, b); > > +} > > + > > + > > +static void quorum_vote(QuorumAIOCB *acb) > > +{ > > + bool quorum = true; > > + int i, j, ret; > > + QuorumVoteValue hash; > > + BDRVQuorumState *s = acb->bqs; > > + QuorumVoteVersion *winner; > > + > > + /* get the index of the first successful read */ > > + for (i = 0; i < s->total; i++) { > > + if (!acb->aios[i].ret) { > > + break; > > + } > > + } > > + > > + /* compare this read with all other successful read looking for quorum > > */ > > + for (j = i + 1; j < s->total; j++) { > > + if (acb->aios[j].ret) { > > + continue; > > + } > > + quorum = quorum_compare(acb, &acb->aios[i].qiov, > > &acb->aios[j].qiov); > > + if (!quorum) { > > + break; > > + } > > + } > > + > > + /* Every successful read agrees -> Quorum */ > > + if (quorum) { > > + quorum_copy_qiov(acb->qiov, &acb->aios[i].qiov); > > + return; > > + } > > + > > + /* compute hashs for each successful read, also store indexes */ > > + for (i = 0; i < s->total; i++) { > > + if (acb->aios[i].ret) { > > + continue; > > + } > > + ret = quorum_compute_hash(acb, i, &hash); > > + assert(ret == 0); > > So you're claiming that this function cannot possibly fail? Why does it > even have a return code then? > > > + quorum_count_vote(&acb->votes, &hash, i); > > + } > > + > > + /* vote to select the most represented version */ > > + winner = quorum_get_vote_winner(&acb->votes); > > + assert(winner != NULL); > > Won't this assertion fail if all requests returned an error? > > > + > > + /* if the winner count is smaller than threshold read fail */ > > s/than/then/ > > > + if (winner->vote_count < s->threshold) { > > + quorum_print_failure(acb); > > + acb->vote_ret = -EIO; > > + fprintf(stderr, "quorum: vote result inferior to threshold\n"); > > Block drivers usually shouldn't print anything to stderr or stdout. > > > + goto free_exit; > > + } > > + > > + /* we have a winner: copy it */ > > + quorum_copy_qiov(acb->qiov, &acb->aios[winner->index].qiov); > > + > > + /* some versions are bad print them */ > > + quorum_print_bad_versions(acb, &winner->value); > > Same here. Is this driver meant to be used in production or only for > debugging? Maybe it should have a debug mode that must explicitly be > enabled and messages are only printed in this mode? Quorum needs to communicate some event to the user for maintainance. Would thowing QMP events be better ? > > > + > > +free_exit: > > + /* free lists */ > > + quorum_free_vote_list(&acb->votes); > > +} > > + > > static BlockDriverAIOCB *quorum_aio_readv(BlockDriverState *bs, > > int64_t sector_num, > > QEMUIOVector *qiov, > > @@ -161,6 +460,8 @@ static BlockDriverAIOCB > > *quorum_aio_readv(BlockDriverState *bs, > > nb_sectors, cb, opaque); > > int i; > > > > + acb->vote = quorum_vote; > > + > > for (i = 0; i < s->total; i++) { > > acb->aios[i].buf = qemu_blockalign(bs->file, qiov->size); > > qemu_iovec_init(&acb->aios[i].qiov, qiov->niov); > > @@ -168,7 +469,7 @@ static BlockDriverAIOCB > > *quorum_aio_readv(BlockDriverState *bs, > > } > > > > for (i = 0; i < s->total; i++) { > > - bdrv_aio_readv(s->bs[i], sector_num, qiov, nb_sectors, > > + bdrv_aio_readv(s->bs[i], sector_num, &acb->aios[i].qiov, > > nb_sectors, > > quorum_aio_cb, &acb->aios[i]); > > } > > > > diff --git a/configure b/configure > > index 4ebb60d..0832d26 100755 > > --- a/configure > > +++ b/configure > > @@ -1733,6 +1733,28 @@ EOF > > fi > > > > ########################################## > > +# Quorum gnutls detection > > +cat > $TMPC <<EOF > > +#include <gnutls/gnutls.h> > > +#include <gnutls/crypto.h> > > +int main(void) {char data[4096], digest[32]; > > +gnutls_hash_fast(GNUTLS_DIG_SHA256, data, 4096, digest); > > +return 0; > > +} > > +EOF > > +qcow_tls_cflags=`$pkg_config --cflags gnutls 2> /dev/null` > > Wait, what has qcow to do with it? > > > +qcow_tls_libs=`$pkg_config --libs gnutls 2> /dev/null` > > +if compile_prog "$qcow_tls_cflags" "$qcow_tls_libs" ; then > > + qcow_tls=yes > > + libs_softmmu="$qcow_tls_libs $libs_softmmu" > > + libs_tools="$qcow_tls_libs $libs_softmmu" > > + QEMU_CFLAGS="$QEMU_CFLAGS $qcow_tls_cflags" > > +else > > + echo "gnutls > 2.10.0 required to compile QEMU" > > + exit 1 > > +fi > > Should this really be a hard dependency? Why not just disable quorum if > the lib isn't there? > > Kevin >