1312 lines
39 KiB
C
1312 lines
39 KiB
C
/*
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* Quorum Block filter
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*
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* Copyright (C) 2012-2014 Nodalink, EURL.
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*
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* Author:
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* Benoît Canet <benoit.canet@irqsave.net>
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*
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* Based on the design and code of blkverify.c (Copyright (C) 2010 IBM, Corp)
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* and blkmirror.c (Copyright (C) 2011 Red Hat, Inc).
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*/
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#include "qemu/osdep.h"
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#include "qemu/cutils.h"
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#include "qemu/module.h"
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#include "qemu/option.h"
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#include "qemu/memalign.h"
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#include "block/block_int.h"
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#include "block/coroutines.h"
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#include "block/qdict.h"
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#include "qapi/error.h"
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#include "qapi/qapi-events-block.h"
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#include "qapi/qmp/qdict.h"
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#include "qapi/qmp/qerror.h"
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#include "qapi/qmp/qlist.h"
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#include "qapi/qmp/qstring.h"
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#include "crypto/hash.h"
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#define HASH_LENGTH 32
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#define INDEXSTR_LEN 32
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#define QUORUM_OPT_VOTE_THRESHOLD "vote-threshold"
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#define QUORUM_OPT_BLKVERIFY "blkverify"
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#define QUORUM_OPT_REWRITE "rewrite-corrupted"
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#define QUORUM_OPT_READ_PATTERN "read-pattern"
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/* This union holds a vote hash value */
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typedef union QuorumVoteValue {
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uint8_t h[HASH_LENGTH]; /* SHA-256 hash */
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int64_t l; /* simpler 64 bits hash */
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} QuorumVoteValue;
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/* A vote item */
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typedef struct QuorumVoteItem {
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int index;
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QLIST_ENTRY(QuorumVoteItem) next;
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} QuorumVoteItem;
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/* this structure is a vote version. A version is the set of votes sharing the
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* same vote value.
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* The set of votes will be tracked with the items field and its cardinality is
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* vote_count.
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*/
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typedef struct QuorumVoteVersion {
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QuorumVoteValue value;
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int index;
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int vote_count;
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QLIST_HEAD(, QuorumVoteItem) items;
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QLIST_ENTRY(QuorumVoteVersion) next;
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} QuorumVoteVersion;
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/* this structure holds a group of vote versions together */
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typedef struct QuorumVotes {
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QLIST_HEAD(, QuorumVoteVersion) vote_list;
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bool (*compare)(QuorumVoteValue *a, QuorumVoteValue *b);
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} QuorumVotes;
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/* the following structure holds the state of one quorum instance */
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typedef struct BDRVQuorumState {
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BdrvChild **children; /* children BlockDriverStates */
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int num_children; /* children count */
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unsigned next_child_index; /* the index of the next child that should
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* be added
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*/
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int threshold; /* if less than threshold children reads gave the
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* same result a quorum error occurs.
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*/
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bool is_blkverify; /* true if the driver is in blkverify mode
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* Writes are mirrored on two children devices.
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* On reads the two children devices' contents are
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* compared and if a difference is spotted its
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* location is printed and the code aborts.
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* It is useful to debug other block drivers by
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* comparing them with a reference one.
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*/
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bool rewrite_corrupted;/* true if the driver must rewrite-on-read corrupted
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* block if Quorum is reached.
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*/
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QuorumReadPattern read_pattern;
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} BDRVQuorumState;
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typedef struct QuorumAIOCB QuorumAIOCB;
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/* Quorum will create one instance of the following structure per operation it
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* performs on its children.
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* So for each read/write operation coming from the upper layer there will be
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* $children_count QuorumChildRequest.
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*/
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typedef struct QuorumChildRequest {
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BlockDriverState *bs;
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QEMUIOVector qiov;
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uint8_t *buf;
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int ret;
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QuorumAIOCB *parent;
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} QuorumChildRequest;
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/* Quorum will use the following structure to track progress of each read/write
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* operation received by the upper layer.
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* This structure hold pointers to the QuorumChildRequest structures instances
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* used to do operations on each children and track overall progress.
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*/
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struct QuorumAIOCB {
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BlockDriverState *bs;
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Coroutine *co;
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/* Request metadata */
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uint64_t offset;
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uint64_t bytes;
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int flags;
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QEMUIOVector *qiov; /* calling IOV */
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QuorumChildRequest *qcrs; /* individual child requests */
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int count; /* number of completed AIOCB */
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int success_count; /* number of successfully completed AIOCB */
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int rewrite_count; /* number of replica to rewrite: count down to
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* zero once writes are fired
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*/
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QuorumVotes votes;
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bool is_read;
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int vote_ret;
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int children_read; /* how many children have been read from */
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};
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typedef struct QuorumCo {
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QuorumAIOCB *acb;
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int idx;
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} QuorumCo;
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static void quorum_aio_finalize(QuorumAIOCB *acb)
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{
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g_free(acb->qcrs);
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g_free(acb);
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}
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static bool quorum_sha256_compare(QuorumVoteValue *a, QuorumVoteValue *b)
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{
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return !memcmp(a->h, b->h, HASH_LENGTH);
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}
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static bool quorum_64bits_compare(QuorumVoteValue *a, QuorumVoteValue *b)
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{
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return a->l == b->l;
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}
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static QuorumAIOCB *coroutine_fn quorum_aio_get(BlockDriverState *bs,
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QEMUIOVector *qiov,
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uint64_t offset, uint64_t bytes,
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int flags)
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{
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BDRVQuorumState *s = bs->opaque;
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QuorumAIOCB *acb = g_new(QuorumAIOCB, 1);
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int i;
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*acb = (QuorumAIOCB) {
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.co = qemu_coroutine_self(),
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.bs = bs,
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.offset = offset,
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.bytes = bytes,
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.flags = flags,
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.qiov = qiov,
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.votes.compare = quorum_sha256_compare,
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.votes.vote_list = QLIST_HEAD_INITIALIZER(acb.votes.vote_list),
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};
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acb->qcrs = g_new0(QuorumChildRequest, s->num_children);
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for (i = 0; i < s->num_children; i++) {
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acb->qcrs[i].buf = NULL;
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acb->qcrs[i].ret = 0;
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acb->qcrs[i].parent = acb;
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}
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return acb;
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}
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static void quorum_report_bad(QuorumOpType type, uint64_t offset,
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uint64_t bytes, char *node_name, int ret)
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{
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const char *msg = NULL;
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int64_t start_sector = offset / BDRV_SECTOR_SIZE;
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int64_t end_sector = DIV_ROUND_UP(offset + bytes, BDRV_SECTOR_SIZE);
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if (ret < 0) {
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msg = strerror(-ret);
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}
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qapi_event_send_quorum_report_bad(type, !!msg, msg, node_name, start_sector,
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end_sector - start_sector);
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}
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static void quorum_report_failure(QuorumAIOCB *acb)
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{
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const char *reference = bdrv_get_device_or_node_name(acb->bs);
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int64_t start_sector = acb->offset / BDRV_SECTOR_SIZE;
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int64_t end_sector = DIV_ROUND_UP(acb->offset + acb->bytes,
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BDRV_SECTOR_SIZE);
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qapi_event_send_quorum_failure(reference, start_sector,
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end_sector - start_sector);
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}
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static int quorum_vote_error(QuorumAIOCB *acb);
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static bool quorum_has_too_much_io_failed(QuorumAIOCB *acb)
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{
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BDRVQuorumState *s = acb->bs->opaque;
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if (acb->success_count < s->threshold) {
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acb->vote_ret = quorum_vote_error(acb);
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quorum_report_failure(acb);
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return true;
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}
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return false;
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}
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static void quorum_copy_qiov(QEMUIOVector *dest, QEMUIOVector *source)
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{
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int i;
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assert(dest->niov == source->niov);
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assert(dest->size == source->size);
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for (i = 0; i < source->niov; i++) {
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assert(dest->iov[i].iov_len == source->iov[i].iov_len);
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memcpy(dest->iov[i].iov_base,
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source->iov[i].iov_base,
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source->iov[i].iov_len);
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}
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}
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static void quorum_report_bad_acb(QuorumChildRequest *sacb, int ret)
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{
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QuorumAIOCB *acb = sacb->parent;
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QuorumOpType type = acb->is_read ? QUORUM_OP_TYPE_READ : QUORUM_OP_TYPE_WRITE;
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quorum_report_bad(type, acb->offset, acb->bytes, sacb->bs->node_name, ret);
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}
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static void quorum_report_bad_versions(BDRVQuorumState *s,
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QuorumAIOCB *acb,
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QuorumVoteValue *value)
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{
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QuorumVoteVersion *version;
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QuorumVoteItem *item;
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QLIST_FOREACH(version, &acb->votes.vote_list, next) {
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if (acb->votes.compare(&version->value, value)) {
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continue;
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}
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QLIST_FOREACH(item, &version->items, next) {
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quorum_report_bad(QUORUM_OP_TYPE_READ, acb->offset, acb->bytes,
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s->children[item->index]->bs->node_name, 0);
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}
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}
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}
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static void coroutine_fn quorum_rewrite_entry(void *opaque)
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{
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QuorumCo *co = opaque;
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QuorumAIOCB *acb = co->acb;
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BDRVQuorumState *s = acb->bs->opaque;
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/* Ignore any errors, it's just a correction attempt for already
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* corrupted data.
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* Mask out BDRV_REQ_WRITE_UNCHANGED because this overwrites the
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* area with different data from the other children. */
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bdrv_co_pwritev(s->children[co->idx], acb->offset, acb->bytes,
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acb->qiov, acb->flags & ~BDRV_REQ_WRITE_UNCHANGED);
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/* Wake up the caller after the last rewrite */
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acb->rewrite_count--;
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if (!acb->rewrite_count) {
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qemu_coroutine_enter_if_inactive(acb->co);
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}
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}
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static bool quorum_rewrite_bad_versions(QuorumAIOCB *acb,
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QuorumVoteValue *value)
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{
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QuorumVoteVersion *version;
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QuorumVoteItem *item;
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int count = 0;
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/* first count the number of bad versions: done first to avoid concurrency
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* issues.
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*/
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QLIST_FOREACH(version, &acb->votes.vote_list, next) {
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if (acb->votes.compare(&version->value, value)) {
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continue;
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}
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QLIST_FOREACH(item, &version->items, next) {
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count++;
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}
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}
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/* quorum_rewrite_entry will count down this to zero */
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acb->rewrite_count = count;
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/* now fire the correcting rewrites */
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QLIST_FOREACH(version, &acb->votes.vote_list, next) {
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if (acb->votes.compare(&version->value, value)) {
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continue;
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}
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QLIST_FOREACH(item, &version->items, next) {
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Coroutine *co;
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QuorumCo data = {
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.acb = acb,
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.idx = item->index,
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};
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co = qemu_coroutine_create(quorum_rewrite_entry, &data);
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qemu_coroutine_enter(co);
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}
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}
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/* return true if any rewrite is done else false */
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return count;
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}
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static void quorum_count_vote(QuorumVotes *votes,
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QuorumVoteValue *value,
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int index)
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{
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QuorumVoteVersion *v = NULL, *version = NULL;
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QuorumVoteItem *item;
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/* look if we have something with this hash */
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QLIST_FOREACH(v, &votes->vote_list, next) {
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if (votes->compare(&v->value, value)) {
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version = v;
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break;
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}
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}
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/* It's a version not yet in the list add it */
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if (!version) {
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version = g_new0(QuorumVoteVersion, 1);
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QLIST_INIT(&version->items);
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memcpy(&version->value, value, sizeof(version->value));
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version->index = index;
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version->vote_count = 0;
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QLIST_INSERT_HEAD(&votes->vote_list, version, next);
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}
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version->vote_count++;
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item = g_new0(QuorumVoteItem, 1);
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item->index = index;
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QLIST_INSERT_HEAD(&version->items, item, next);
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}
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static void quorum_free_vote_list(QuorumVotes *votes)
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{
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QuorumVoteVersion *version, *next_version;
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QuorumVoteItem *item, *next_item;
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QLIST_FOREACH_SAFE(version, &votes->vote_list, next, next_version) {
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QLIST_REMOVE(version, next);
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QLIST_FOREACH_SAFE(item, &version->items, next, next_item) {
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QLIST_REMOVE(item, next);
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g_free(item);
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}
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g_free(version);
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}
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}
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static int quorum_compute_hash(QuorumAIOCB *acb, int i, QuorumVoteValue *hash)
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{
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QEMUIOVector *qiov = &acb->qcrs[i].qiov;
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size_t len = sizeof(hash->h);
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uint8_t *data = hash->h;
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/* XXX - would be nice if we could pass in the Error **
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* and propagate that back, but this quorum code is
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* restricted to just errno values currently */
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if (qcrypto_hash_bytesv(QCRYPTO_HASH_ALG_SHA256,
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qiov->iov, qiov->niov,
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&data, &len,
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NULL) < 0) {
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return -EINVAL;
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}
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return 0;
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}
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static QuorumVoteVersion *quorum_get_vote_winner(QuorumVotes *votes)
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{
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int max = 0;
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QuorumVoteVersion *candidate, *winner = NULL;
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QLIST_FOREACH(candidate, &votes->vote_list, next) {
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if (candidate->vote_count > max) {
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max = candidate->vote_count;
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winner = candidate;
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}
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}
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return winner;
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}
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/* qemu_iovec_compare is handy for blkverify mode because it returns the first
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* differing byte location. Yet it is handcoded to compare vectors one byte
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* after another so it does not benefit from the libc SIMD optimizations.
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* quorum_iovec_compare is written for speed and should be used in the non
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* blkverify mode of quorum.
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*/
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static bool quorum_iovec_compare(QEMUIOVector *a, QEMUIOVector *b)
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{
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int i;
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int result;
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assert(a->niov == b->niov);
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for (i = 0; i < a->niov; i++) {
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assert(a->iov[i].iov_len == b->iov[i].iov_len);
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result = memcmp(a->iov[i].iov_base,
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b->iov[i].iov_base,
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a->iov[i].iov_len);
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if (result) {
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return false;
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}
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}
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return true;
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}
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static bool quorum_compare(QuorumAIOCB *acb, QEMUIOVector *a, QEMUIOVector *b)
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{
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BDRVQuorumState *s = acb->bs->opaque;
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ssize_t offset;
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/* This driver will replace blkverify in this particular case */
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if (s->is_blkverify) {
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offset = qemu_iovec_compare(a, b);
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if (offset != -1) {
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fprintf(stderr, "quorum: offset=%" PRIu64 " bytes=%" PRIu64
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" contents mismatch at offset %" PRIu64 "\n",
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acb->offset, acb->bytes, acb->offset + offset);
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exit(1);
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}
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return true;
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}
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|
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return quorum_iovec_compare(a, b);
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}
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/* Do a vote to get the error code */
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static int quorum_vote_error(QuorumAIOCB *acb)
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{
|
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BDRVQuorumState *s = acb->bs->opaque;
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QuorumVoteVersion *winner = NULL;
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QuorumVotes error_votes;
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QuorumVoteValue result_value;
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int i, ret = 0;
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bool error = false;
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QLIST_INIT(&error_votes.vote_list);
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error_votes.compare = quorum_64bits_compare;
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for (i = 0; i < s->num_children; i++) {
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ret = acb->qcrs[i].ret;
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if (ret) {
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error = true;
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result_value.l = ret;
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quorum_count_vote(&error_votes, &result_value, i);
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}
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}
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if (error) {
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winner = quorum_get_vote_winner(&error_votes);
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ret = winner->value.l;
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}
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quorum_free_vote_list(&error_votes);
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return ret;
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}
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|
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static void quorum_vote(QuorumAIOCB *acb)
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{
|
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bool quorum = true;
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int i, j, ret;
|
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QuorumVoteValue hash;
|
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BDRVQuorumState *s = acb->bs->opaque;
|
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QuorumVoteVersion *winner;
|
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|
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if (quorum_has_too_much_io_failed(acb)) {
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return;
|
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}
|
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|
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/* get the index of the first successful read */
|
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for (i = 0; i < s->num_children; i++) {
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if (!acb->qcrs[i].ret) {
|
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break;
|
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}
|
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}
|
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|
|
assert(i < s->num_children);
|
|
|
|
/* compare this read with all other successful reads stopping at quorum
|
|
* failure
|
|
*/
|
|
for (j = i + 1; j < s->num_children; j++) {
|
|
if (acb->qcrs[j].ret) {
|
|
continue;
|
|
}
|
|
quorum = quorum_compare(acb, &acb->qcrs[i].qiov, &acb->qcrs[j].qiov);
|
|
if (!quorum) {
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* Every successful read agrees */
|
|
if (quorum) {
|
|
quorum_copy_qiov(acb->qiov, &acb->qcrs[i].qiov);
|
|
return;
|
|
}
|
|
|
|
/* compute hashes for each successful read, also store indexes */
|
|
for (i = 0; i < s->num_children; i++) {
|
|
if (acb->qcrs[i].ret) {
|
|
continue;
|
|
}
|
|
ret = quorum_compute_hash(acb, i, &hash);
|
|
/* if ever the hash computation failed */
|
|
if (ret < 0) {
|
|
acb->vote_ret = ret;
|
|
goto free_exit;
|
|
}
|
|
quorum_count_vote(&acb->votes, &hash, i);
|
|
}
|
|
|
|
/* vote to select the most represented version */
|
|
winner = quorum_get_vote_winner(&acb->votes);
|
|
|
|
/* if the winner count is smaller than threshold the read fails */
|
|
if (winner->vote_count < s->threshold) {
|
|
quorum_report_failure(acb);
|
|
acb->vote_ret = -EIO;
|
|
goto free_exit;
|
|
}
|
|
|
|
/* we have a winner: copy it */
|
|
quorum_copy_qiov(acb->qiov, &acb->qcrs[winner->index].qiov);
|
|
|
|
/* some versions are bad print them */
|
|
quorum_report_bad_versions(s, acb, &winner->value);
|
|
|
|
/* corruption correction is enabled */
|
|
if (s->rewrite_corrupted) {
|
|
quorum_rewrite_bad_versions(acb, &winner->value);
|
|
}
|
|
|
|
free_exit:
|
|
/* free lists */
|
|
quorum_free_vote_list(&acb->votes);
|
|
}
|
|
|
|
static void coroutine_fn read_quorum_children_entry(void *opaque)
|
|
{
|
|
QuorumCo *co = opaque;
|
|
QuorumAIOCB *acb = co->acb;
|
|
BDRVQuorumState *s = acb->bs->opaque;
|
|
int i = co->idx;
|
|
QuorumChildRequest *sacb = &acb->qcrs[i];
|
|
|
|
sacb->bs = s->children[i]->bs;
|
|
sacb->ret = bdrv_co_preadv(s->children[i], acb->offset, acb->bytes,
|
|
&acb->qcrs[i].qiov, 0);
|
|
|
|
if (sacb->ret == 0) {
|
|
acb->success_count++;
|
|
} else {
|
|
quorum_report_bad_acb(sacb, sacb->ret);
|
|
}
|
|
|
|
acb->count++;
|
|
assert(acb->count <= s->num_children);
|
|
assert(acb->success_count <= s->num_children);
|
|
|
|
/* Wake up the caller after the last read */
|
|
if (acb->count == s->num_children) {
|
|
qemu_coroutine_enter_if_inactive(acb->co);
|
|
}
|
|
}
|
|
|
|
static int coroutine_fn read_quorum_children(QuorumAIOCB *acb)
|
|
{
|
|
BDRVQuorumState *s = acb->bs->opaque;
|
|
int i;
|
|
|
|
acb->children_read = s->num_children;
|
|
for (i = 0; i < s->num_children; i++) {
|
|
acb->qcrs[i].buf = qemu_blockalign(s->children[i]->bs, acb->qiov->size);
|
|
qemu_iovec_init(&acb->qcrs[i].qiov, acb->qiov->niov);
|
|
qemu_iovec_clone(&acb->qcrs[i].qiov, acb->qiov, acb->qcrs[i].buf);
|
|
}
|
|
|
|
for (i = 0; i < s->num_children; i++) {
|
|
Coroutine *co;
|
|
QuorumCo data = {
|
|
.acb = acb,
|
|
.idx = i,
|
|
};
|
|
|
|
co = qemu_coroutine_create(read_quorum_children_entry, &data);
|
|
qemu_coroutine_enter(co);
|
|
}
|
|
|
|
while (acb->count < s->num_children) {
|
|
qemu_coroutine_yield();
|
|
}
|
|
|
|
/* Do the vote on read */
|
|
quorum_vote(acb);
|
|
for (i = 0; i < s->num_children; i++) {
|
|
qemu_vfree(acb->qcrs[i].buf);
|
|
qemu_iovec_destroy(&acb->qcrs[i].qiov);
|
|
}
|
|
|
|
while (acb->rewrite_count) {
|
|
qemu_coroutine_yield();
|
|
}
|
|
|
|
return acb->vote_ret;
|
|
}
|
|
|
|
static int coroutine_fn read_fifo_child(QuorumAIOCB *acb)
|
|
{
|
|
BDRVQuorumState *s = acb->bs->opaque;
|
|
int n, ret;
|
|
|
|
/* We try to read the next child in FIFO order if we failed to read */
|
|
do {
|
|
n = acb->children_read++;
|
|
acb->qcrs[n].bs = s->children[n]->bs;
|
|
ret = bdrv_co_preadv(s->children[n], acb->offset, acb->bytes,
|
|
acb->qiov, 0);
|
|
if (ret < 0) {
|
|
quorum_report_bad_acb(&acb->qcrs[n], ret);
|
|
}
|
|
} while (ret < 0 && acb->children_read < s->num_children);
|
|
|
|
/* FIXME: rewrite failed children if acb->children_read > 1? */
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int coroutine_fn quorum_co_preadv(BlockDriverState *bs,
|
|
int64_t offset, int64_t bytes,
|
|
QEMUIOVector *qiov,
|
|
BdrvRequestFlags flags)
|
|
{
|
|
BDRVQuorumState *s = bs->opaque;
|
|
QuorumAIOCB *acb = quorum_aio_get(bs, qiov, offset, bytes, flags);
|
|
int ret;
|
|
|
|
acb->is_read = true;
|
|
acb->children_read = 0;
|
|
|
|
if (s->read_pattern == QUORUM_READ_PATTERN_QUORUM) {
|
|
ret = read_quorum_children(acb);
|
|
} else {
|
|
ret = read_fifo_child(acb);
|
|
}
|
|
quorum_aio_finalize(acb);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static void coroutine_fn write_quorum_entry(void *opaque)
|
|
{
|
|
QuorumCo *co = opaque;
|
|
QuorumAIOCB *acb = co->acb;
|
|
BDRVQuorumState *s = acb->bs->opaque;
|
|
int i = co->idx;
|
|
QuorumChildRequest *sacb = &acb->qcrs[i];
|
|
|
|
sacb->bs = s->children[i]->bs;
|
|
if (acb->flags & BDRV_REQ_ZERO_WRITE) {
|
|
sacb->ret = bdrv_co_pwrite_zeroes(s->children[i], acb->offset,
|
|
acb->bytes, acb->flags);
|
|
} else {
|
|
sacb->ret = bdrv_co_pwritev(s->children[i], acb->offset, acb->bytes,
|
|
acb->qiov, acb->flags);
|
|
}
|
|
if (sacb->ret == 0) {
|
|
acb->success_count++;
|
|
} else {
|
|
quorum_report_bad_acb(sacb, sacb->ret);
|
|
}
|
|
acb->count++;
|
|
assert(acb->count <= s->num_children);
|
|
assert(acb->success_count <= s->num_children);
|
|
|
|
/* Wake up the caller after the last write */
|
|
if (acb->count == s->num_children) {
|
|
qemu_coroutine_enter_if_inactive(acb->co);
|
|
}
|
|
}
|
|
|
|
static int coroutine_fn quorum_co_pwritev(BlockDriverState *bs, int64_t offset,
|
|
int64_t bytes, QEMUIOVector *qiov,
|
|
BdrvRequestFlags flags)
|
|
{
|
|
BDRVQuorumState *s = bs->opaque;
|
|
QuorumAIOCB *acb = quorum_aio_get(bs, qiov, offset, bytes, flags);
|
|
int i, ret;
|
|
|
|
for (i = 0; i < s->num_children; i++) {
|
|
Coroutine *co;
|
|
QuorumCo data = {
|
|
.acb = acb,
|
|
.idx = i,
|
|
};
|
|
|
|
co = qemu_coroutine_create(write_quorum_entry, &data);
|
|
qemu_coroutine_enter(co);
|
|
}
|
|
|
|
while (acb->count < s->num_children) {
|
|
qemu_coroutine_yield();
|
|
}
|
|
|
|
quorum_has_too_much_io_failed(acb);
|
|
|
|
ret = acb->vote_ret;
|
|
quorum_aio_finalize(acb);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int coroutine_fn quorum_co_pwrite_zeroes(BlockDriverState *bs,
|
|
int64_t offset, int64_t bytes,
|
|
BdrvRequestFlags flags)
|
|
|
|
{
|
|
return quorum_co_pwritev(bs, offset, bytes, NULL,
|
|
flags | BDRV_REQ_ZERO_WRITE);
|
|
}
|
|
|
|
static int64_t quorum_getlength(BlockDriverState *bs)
|
|
{
|
|
BDRVQuorumState *s = bs->opaque;
|
|
int64_t result;
|
|
int i;
|
|
|
|
/* check that all file have the same length */
|
|
result = bdrv_getlength(s->children[0]->bs);
|
|
if (result < 0) {
|
|
return result;
|
|
}
|
|
for (i = 1; i < s->num_children; i++) {
|
|
int64_t value = bdrv_getlength(s->children[i]->bs);
|
|
if (value < 0) {
|
|
return value;
|
|
}
|
|
if (value != result) {
|
|
return -EIO;
|
|
}
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
static coroutine_fn int quorum_co_flush(BlockDriverState *bs)
|
|
{
|
|
BDRVQuorumState *s = bs->opaque;
|
|
QuorumVoteVersion *winner = NULL;
|
|
QuorumVotes error_votes;
|
|
QuorumVoteValue result_value;
|
|
int i;
|
|
int result = 0;
|
|
int success_count = 0;
|
|
|
|
QLIST_INIT(&error_votes.vote_list);
|
|
error_votes.compare = quorum_64bits_compare;
|
|
|
|
for (i = 0; i < s->num_children; i++) {
|
|
result = bdrv_co_flush(s->children[i]->bs);
|
|
if (result) {
|
|
quorum_report_bad(QUORUM_OP_TYPE_FLUSH, 0, 0,
|
|
s->children[i]->bs->node_name, result);
|
|
result_value.l = result;
|
|
quorum_count_vote(&error_votes, &result_value, i);
|
|
} else {
|
|
success_count++;
|
|
}
|
|
}
|
|
|
|
if (success_count >= s->threshold) {
|
|
result = 0;
|
|
} else {
|
|
winner = quorum_get_vote_winner(&error_votes);
|
|
result = winner->value.l;
|
|
}
|
|
quorum_free_vote_list(&error_votes);
|
|
|
|
return result;
|
|
}
|
|
|
|
static bool quorum_recurse_can_replace(BlockDriverState *bs,
|
|
BlockDriverState *to_replace)
|
|
{
|
|
BDRVQuorumState *s = bs->opaque;
|
|
int i;
|
|
|
|
for (i = 0; i < s->num_children; i++) {
|
|
/*
|
|
* We have no idea whether our children show the same data as
|
|
* this node (@bs). It is actually highly likely that
|
|
* @to_replace does not, because replacing a broken child is
|
|
* one of the main use cases here.
|
|
*
|
|
* We do know that the new BDS will match @bs, so replacing
|
|
* any of our children by it will be safe. It cannot change
|
|
* the data this quorum node presents to its parents.
|
|
*
|
|
* However, replacing @to_replace by @bs in any of our
|
|
* children's chains may change visible data somewhere in
|
|
* there. We therefore cannot recurse down those chains with
|
|
* bdrv_recurse_can_replace().
|
|
* (More formally, bdrv_recurse_can_replace() requires that
|
|
* @to_replace will be replaced by something matching the @bs
|
|
* passed to it. We cannot guarantee that.)
|
|
*
|
|
* Thus, we can only check whether any of our immediate
|
|
* children matches @to_replace.
|
|
*
|
|
* (In the future, we might add a function to recurse down a
|
|
* chain that checks that nothing there cares about a change
|
|
* in data from the respective child in question. For
|
|
* example, most filters do not care when their child's data
|
|
* suddenly changes, as long as their parents do not care.)
|
|
*/
|
|
if (s->children[i]->bs == to_replace) {
|
|
/*
|
|
* We now have to ensure that there is no other parent
|
|
* that cares about replacing this child by a node with
|
|
* potentially different data.
|
|
* We do so by checking whether there are any other parents
|
|
* at all, which is stricter than necessary, but also very
|
|
* simple. (We may decide to implement something more
|
|
* complex and permissive when there is an actual need for
|
|
* it.)
|
|
*/
|
|
return QLIST_FIRST(&to_replace->parents) == s->children[i] &&
|
|
QLIST_NEXT(s->children[i], next_parent) == NULL;
|
|
}
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
static int quorum_valid_threshold(int threshold, int num_children, Error **errp)
|
|
{
|
|
|
|
if (threshold < 1) {
|
|
error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
|
|
"vote-threshold", "a value >= 1");
|
|
return -ERANGE;
|
|
}
|
|
|
|
if (threshold > num_children) {
|
|
error_setg(errp, "threshold may not exceed children count");
|
|
return -ERANGE;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static QemuOptsList quorum_runtime_opts = {
|
|
.name = "quorum",
|
|
.head = QTAILQ_HEAD_INITIALIZER(quorum_runtime_opts.head),
|
|
.desc = {
|
|
{
|
|
.name = QUORUM_OPT_VOTE_THRESHOLD,
|
|
.type = QEMU_OPT_NUMBER,
|
|
.help = "The number of vote needed for reaching quorum",
|
|
},
|
|
{
|
|
.name = QUORUM_OPT_BLKVERIFY,
|
|
.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",
|
|
},
|
|
{
|
|
.name = QUORUM_OPT_READ_PATTERN,
|
|
.type = QEMU_OPT_STRING,
|
|
.help = "Allowed pattern: quorum, fifo. Quorum is default",
|
|
},
|
|
{ /* end of list */ }
|
|
},
|
|
};
|
|
|
|
static void quorum_refresh_flags(BlockDriverState *bs)
|
|
{
|
|
BDRVQuorumState *s = bs->opaque;
|
|
int i;
|
|
|
|
bs->supported_zero_flags =
|
|
BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK;
|
|
|
|
for (i = 0; i < s->num_children; i++) {
|
|
bs->supported_zero_flags &= s->children[i]->bs->supported_zero_flags;
|
|
}
|
|
|
|
bs->supported_zero_flags |= BDRV_REQ_WRITE_UNCHANGED;
|
|
}
|
|
|
|
static int quorum_open(BlockDriverState *bs, QDict *options, int flags,
|
|
Error **errp)
|
|
{
|
|
BDRVQuorumState *s = bs->opaque;
|
|
QemuOpts *opts = NULL;
|
|
const char *pattern_str;
|
|
bool *opened;
|
|
int i;
|
|
int ret = 0;
|
|
|
|
qdict_flatten(options);
|
|
|
|
/* count how many different children are present */
|
|
s->num_children = qdict_array_entries(options, "children.");
|
|
if (s->num_children < 0) {
|
|
error_setg(errp, "Option children is not a valid array");
|
|
ret = -EINVAL;
|
|
goto exit;
|
|
}
|
|
if (s->num_children < 1) {
|
|
error_setg(errp, "Number of provided children must be 1 or more");
|
|
ret = -EINVAL;
|
|
goto exit;
|
|
}
|
|
|
|
opts = qemu_opts_create(&quorum_runtime_opts, NULL, 0, &error_abort);
|
|
if (!qemu_opts_absorb_qdict(opts, options, errp)) {
|
|
ret = -EINVAL;
|
|
goto exit;
|
|
}
|
|
|
|
s->threshold = qemu_opt_get_number(opts, QUORUM_OPT_VOTE_THRESHOLD, 0);
|
|
/* and validate it against s->num_children */
|
|
ret = quorum_valid_threshold(s->threshold, s->num_children, errp);
|
|
if (ret < 0) {
|
|
goto exit;
|
|
}
|
|
|
|
pattern_str = qemu_opt_get(opts, QUORUM_OPT_READ_PATTERN);
|
|
if (!pattern_str) {
|
|
ret = QUORUM_READ_PATTERN_QUORUM;
|
|
} else {
|
|
ret = qapi_enum_parse(&QuorumReadPattern_lookup, pattern_str,
|
|
-EINVAL, NULL);
|
|
}
|
|
if (ret < 0) {
|
|
error_setg(errp, "Please set read-pattern as fifo or quorum");
|
|
goto exit;
|
|
}
|
|
s->read_pattern = ret;
|
|
|
|
if (s->read_pattern == QUORUM_READ_PATTERN_QUORUM) {
|
|
s->is_blkverify = qemu_opt_get_bool(opts, QUORUM_OPT_BLKVERIFY, false);
|
|
if (s->is_blkverify && (s->num_children != 2 || s->threshold != 2)) {
|
|
error_setg(errp, "blkverify=on can only be set if there are "
|
|
"exactly two files and vote-threshold is 2");
|
|
ret = -EINVAL;
|
|
goto exit;
|
|
}
|
|
|
|
s->rewrite_corrupted = qemu_opt_get_bool(opts, QUORUM_OPT_REWRITE,
|
|
false);
|
|
if (s->rewrite_corrupted && s->is_blkverify) {
|
|
error_setg(errp,
|
|
"rewrite-corrupted=on cannot be used with blkverify=on");
|
|
ret = -EINVAL;
|
|
goto exit;
|
|
}
|
|
}
|
|
|
|
/* allocate the children array */
|
|
s->children = g_new0(BdrvChild *, s->num_children);
|
|
opened = g_new0(bool, s->num_children);
|
|
|
|
for (i = 0; i < s->num_children; i++) {
|
|
char indexstr[INDEXSTR_LEN];
|
|
ret = snprintf(indexstr, INDEXSTR_LEN, "children.%d", i);
|
|
assert(ret < INDEXSTR_LEN);
|
|
|
|
s->children[i] = bdrv_open_child(NULL, options, indexstr, bs,
|
|
&child_of_bds, BDRV_CHILD_DATA, false,
|
|
errp);
|
|
if (!s->children[i]) {
|
|
ret = -EINVAL;
|
|
goto close_exit;
|
|
}
|
|
|
|
opened[i] = true;
|
|
}
|
|
s->next_child_index = s->num_children;
|
|
|
|
bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED;
|
|
quorum_refresh_flags(bs);
|
|
|
|
g_free(opened);
|
|
goto exit;
|
|
|
|
close_exit:
|
|
/* cleanup on error */
|
|
for (i = 0; i < s->num_children; i++) {
|
|
if (!opened[i]) {
|
|
continue;
|
|
}
|
|
bdrv_unref_child(bs, s->children[i]);
|
|
}
|
|
g_free(s->children);
|
|
g_free(opened);
|
|
exit:
|
|
qemu_opts_del(opts);
|
|
return ret;
|
|
}
|
|
|
|
static void quorum_close(BlockDriverState *bs)
|
|
{
|
|
BDRVQuorumState *s = bs->opaque;
|
|
int i;
|
|
|
|
for (i = 0; i < s->num_children; i++) {
|
|
bdrv_unref_child(bs, s->children[i]);
|
|
}
|
|
|
|
g_free(s->children);
|
|
}
|
|
|
|
static void quorum_add_child(BlockDriverState *bs, BlockDriverState *child_bs,
|
|
Error **errp)
|
|
{
|
|
BDRVQuorumState *s = bs->opaque;
|
|
BdrvChild *child;
|
|
char indexstr[INDEXSTR_LEN];
|
|
int ret;
|
|
|
|
if (s->is_blkverify) {
|
|
error_setg(errp, "Cannot add a child to a quorum in blkverify mode");
|
|
return;
|
|
}
|
|
|
|
assert(s->num_children <= INT_MAX / sizeof(BdrvChild *));
|
|
if (s->num_children == INT_MAX / sizeof(BdrvChild *) ||
|
|
s->next_child_index == UINT_MAX) {
|
|
error_setg(errp, "Too many children");
|
|
return;
|
|
}
|
|
|
|
ret = snprintf(indexstr, INDEXSTR_LEN, "children.%u", s->next_child_index);
|
|
if (ret < 0 || ret >= INDEXSTR_LEN) {
|
|
error_setg(errp, "cannot generate child name");
|
|
return;
|
|
}
|
|
s->next_child_index++;
|
|
|
|
bdrv_drained_begin(bs);
|
|
|
|
/* We can safely add the child now */
|
|
bdrv_ref(child_bs);
|
|
|
|
child = bdrv_attach_child(bs, child_bs, indexstr, &child_of_bds,
|
|
BDRV_CHILD_DATA, errp);
|
|
if (child == NULL) {
|
|
s->next_child_index--;
|
|
goto out;
|
|
}
|
|
s->children = g_renew(BdrvChild *, s->children, s->num_children + 1);
|
|
s->children[s->num_children++] = child;
|
|
quorum_refresh_flags(bs);
|
|
|
|
out:
|
|
bdrv_drained_end(bs);
|
|
}
|
|
|
|
static void quorum_del_child(BlockDriverState *bs, BdrvChild *child,
|
|
Error **errp)
|
|
{
|
|
BDRVQuorumState *s = bs->opaque;
|
|
char indexstr[INDEXSTR_LEN];
|
|
int i;
|
|
|
|
for (i = 0; i < s->num_children; i++) {
|
|
if (s->children[i] == child) {
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* we have checked it in bdrv_del_child() */
|
|
assert(i < s->num_children);
|
|
|
|
if (s->num_children <= s->threshold) {
|
|
error_setg(errp,
|
|
"The number of children cannot be lower than the vote threshold %d",
|
|
s->threshold);
|
|
return;
|
|
}
|
|
|
|
/* We know now that num_children > threshold, so blkverify must be false */
|
|
assert(!s->is_blkverify);
|
|
|
|
snprintf(indexstr, INDEXSTR_LEN, "children.%u", s->next_child_index - 1);
|
|
if (!strncmp(child->name, indexstr, INDEXSTR_LEN)) {
|
|
s->next_child_index--;
|
|
}
|
|
|
|
bdrv_drained_begin(bs);
|
|
|
|
/* We can safely remove this child now */
|
|
memmove(&s->children[i], &s->children[i + 1],
|
|
(s->num_children - i - 1) * sizeof(BdrvChild *));
|
|
s->children = g_renew(BdrvChild *, s->children, --s->num_children);
|
|
bdrv_unref_child(bs, child);
|
|
|
|
quorum_refresh_flags(bs);
|
|
bdrv_drained_end(bs);
|
|
}
|
|
|
|
static void quorum_gather_child_options(BlockDriverState *bs, QDict *target,
|
|
bool backing_overridden)
|
|
{
|
|
BDRVQuorumState *s = bs->opaque;
|
|
QList *children_list;
|
|
int i;
|
|
|
|
/*
|
|
* The generic implementation for gathering child options in
|
|
* bdrv_refresh_filename() would use the names of the children
|
|
* as specified for bdrv_open_child() or bdrv_attach_child(),
|
|
* which is "children.%u" with %u being a value
|
|
* (s->next_child_index) that is incremented each time a new child
|
|
* is added (and never decremented). Since children can be
|
|
* deleted at runtime, there may be gaps in that enumeration.
|
|
* When creating a new quorum BDS and specifying the children for
|
|
* it through runtime options, the enumeration used there may not
|
|
* have any gaps, though.
|
|
*
|
|
* Therefore, we have to create a new gap-less enumeration here
|
|
* (which we can achieve by simply putting all of the children's
|
|
* full_open_options into a QList).
|
|
*
|
|
* XXX: Note that there are issues with the current child option
|
|
* structure quorum uses (such as the fact that children do
|
|
* not really have unique permanent names). Therefore, this
|
|
* is going to have to change in the future and ideally we
|
|
* want quorum to be covered by the generic implementation.
|
|
*/
|
|
|
|
children_list = qlist_new();
|
|
qdict_put(target, "children", children_list);
|
|
|
|
for (i = 0; i < s->num_children; i++) {
|
|
qlist_append(children_list,
|
|
qobject_ref(s->children[i]->bs->full_open_options));
|
|
}
|
|
}
|
|
|
|
static char *quorum_dirname(BlockDriverState *bs, Error **errp)
|
|
{
|
|
/* In general, there are multiple BDSs with different dirnames below this
|
|
* one; so there is no unique dirname we could return (unless all are equal
|
|
* by chance, or there is only one). Therefore, to be consistent, just
|
|
* always return NULL. */
|
|
error_setg(errp, "Cannot generate a base directory for quorum nodes");
|
|
return NULL;
|
|
}
|
|
|
|
static void quorum_child_perm(BlockDriverState *bs, BdrvChild *c,
|
|
BdrvChildRole role,
|
|
BlockReopenQueue *reopen_queue,
|
|
uint64_t perm, uint64_t shared,
|
|
uint64_t *nperm, uint64_t *nshared)
|
|
{
|
|
BDRVQuorumState *s = bs->opaque;
|
|
|
|
*nperm = perm & DEFAULT_PERM_PASSTHROUGH;
|
|
if (s->rewrite_corrupted) {
|
|
*nperm |= BLK_PERM_WRITE;
|
|
}
|
|
|
|
/*
|
|
* We cannot share RESIZE or WRITE, as this would make the
|
|
* children differ from each other.
|
|
*/
|
|
*nshared = (shared & (BLK_PERM_CONSISTENT_READ |
|
|
BLK_PERM_WRITE_UNCHANGED))
|
|
| DEFAULT_PERM_UNCHANGED;
|
|
}
|
|
|
|
/*
|
|
* Each one of the children can report different status flags even
|
|
* when they contain the same data, so what this function does is
|
|
* return BDRV_BLOCK_ZERO if *all* children agree that a certain
|
|
* region contains zeroes, and BDRV_BLOCK_DATA otherwise.
|
|
*/
|
|
static int coroutine_fn quorum_co_block_status(BlockDriverState *bs,
|
|
bool want_zero,
|
|
int64_t offset, int64_t count,
|
|
int64_t *pnum, int64_t *map,
|
|
BlockDriverState **file)
|
|
{
|
|
BDRVQuorumState *s = bs->opaque;
|
|
int i, ret;
|
|
int64_t pnum_zero = count;
|
|
int64_t pnum_data = 0;
|
|
|
|
for (i = 0; i < s->num_children; i++) {
|
|
int64_t bytes;
|
|
ret = bdrv_co_common_block_status_above(s->children[i]->bs, NULL, false,
|
|
want_zero, offset, count,
|
|
&bytes, NULL, NULL, NULL);
|
|
if (ret < 0) {
|
|
quorum_report_bad(QUORUM_OP_TYPE_READ, offset, count,
|
|
s->children[i]->bs->node_name, ret);
|
|
pnum_data = count;
|
|
break;
|
|
}
|
|
/*
|
|
* Even if all children agree about whether there are zeroes
|
|
* or not at @offset they might disagree on the size, so use
|
|
* the smallest when reporting BDRV_BLOCK_ZERO and the largest
|
|
* when reporting BDRV_BLOCK_DATA.
|
|
*/
|
|
if (ret & BDRV_BLOCK_ZERO) {
|
|
pnum_zero = MIN(pnum_zero, bytes);
|
|
} else {
|
|
pnum_data = MAX(pnum_data, bytes);
|
|
}
|
|
}
|
|
|
|
if (pnum_data) {
|
|
*pnum = pnum_data;
|
|
return BDRV_BLOCK_DATA;
|
|
} else {
|
|
*pnum = pnum_zero;
|
|
return BDRV_BLOCK_ZERO;
|
|
}
|
|
}
|
|
|
|
static const char *const quorum_strong_runtime_opts[] = {
|
|
QUORUM_OPT_VOTE_THRESHOLD,
|
|
QUORUM_OPT_BLKVERIFY,
|
|
QUORUM_OPT_REWRITE,
|
|
QUORUM_OPT_READ_PATTERN,
|
|
|
|
NULL
|
|
};
|
|
|
|
static BlockDriver bdrv_quorum = {
|
|
.format_name = "quorum",
|
|
|
|
.instance_size = sizeof(BDRVQuorumState),
|
|
|
|
.bdrv_open = quorum_open,
|
|
.bdrv_close = quorum_close,
|
|
.bdrv_gather_child_options = quorum_gather_child_options,
|
|
.bdrv_dirname = quorum_dirname,
|
|
.bdrv_co_block_status = quorum_co_block_status,
|
|
|
|
.bdrv_co_flush = quorum_co_flush,
|
|
|
|
.bdrv_getlength = quorum_getlength,
|
|
|
|
.bdrv_co_preadv = quorum_co_preadv,
|
|
.bdrv_co_pwritev = quorum_co_pwritev,
|
|
.bdrv_co_pwrite_zeroes = quorum_co_pwrite_zeroes,
|
|
|
|
.bdrv_add_child = quorum_add_child,
|
|
.bdrv_del_child = quorum_del_child,
|
|
|
|
.bdrv_child_perm = quorum_child_perm,
|
|
|
|
.bdrv_recurse_can_replace = quorum_recurse_can_replace,
|
|
|
|
.strong_runtime_opts = quorum_strong_runtime_opts,
|
|
};
|
|
|
|
static void bdrv_quorum_init(void)
|
|
{
|
|
if (!qcrypto_hash_supports(QCRYPTO_HASH_ALG_SHA256)) {
|
|
/* SHA256 hash support is required for quorum device */
|
|
return;
|
|
}
|
|
bdrv_register(&bdrv_quorum);
|
|
}
|
|
|
|
block_init(bdrv_quorum_init);
|