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qemu: Support O_DIRECT with mapped-ram on save

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When using the mapped-ram migration capability, direct IO is
enabled by setting the "direct-io" migration parameter to
"true" and passing QEMU an additional fd with O_DIRECT set.

Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
This commit is contained in:
Jim Fehlig 2024-07-22 11:34:44 -06:00
parent 28a0621528
commit 06bdb1b6c7
8 changed files with 53 additions and 16 deletions
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10
src/qemu/qemu_driver.c
View File

@ -2668,7 +2668,8 @@ qemuDomainSaveInternal(virQEMUDriver *driver,
goto endjob;
xml = NULL;
if (!(saveParams = qemuMigrationParamsForSave(format == QEMU_SAVE_FORMAT_SPARSE)))
if (!(saveParams = qemuMigrationParamsForSave(format == QEMU_SAVE_FORMAT_SPARSE,
flags)))
goto endjob;
ret = qemuSaveImageCreate(driver, vm, path, data, compressor,
@ -3118,7 +3119,7 @@ doCoreDump(virQEMUDriver *driver,
if (!(dump_params = qemuMigrationParamsNew()))
goto cleanup;
if (qemuMigrationSrcToFile(driver, vm, &fd, compressor,
if (qemuMigrationSrcToFile(driver, vm, path, &fd, compressor,
dump_params, dump_flags, VIR_ASYNC_JOB_DUMP) < 0)
goto cleanup;
}
@ -5762,7 +5763,7 @@ qemuDomainRestoreInternal(virConnectPtr conn,
goto cleanup;
sparse = data->header.format == QEMU_SAVE_FORMAT_SPARSE;
if (!(restoreParams = qemuMigrationParamsForSave(sparse)))
if (!(restoreParams = qemuMigrationParamsForSave(sparse, flags)))
goto cleanup;
fd = qemuSaveImageOpen(driver, path,
@ -6096,7 +6097,8 @@ qemuDomainObjRestore(virConnectPtr conn,
}
sparse = data->header.format == QEMU_SAVE_FORMAT_SPARSE;
if (!(restoreParams = qemuMigrationParamsForSave(sparse)))
if (!(restoreParams = qemuMigrationParamsForSave(sparse,
bypass_cache ? VIR_DOMAIN_SAVE_BYPASS_CACHE : 0)))
return -1;
fd = qemuSaveImageOpen(driver, path, bypass_cache, sparse, &wrapperFd, false);

32
src/qemu/qemu_migration.c
View File

@ -7183,17 +7183,36 @@ qemuMigrationSrcToLegacyFile(virQEMUDriver *driver,
static int
qemuMigrationSrcToSparseFile(virQEMUDriver *driver,
virDomainObj *vm,
const char *path,
int *fd,
unsigned int flags,
virDomainAsyncJob asyncJob)
{
g_autoptr(virQEMUDriverConfig) cfg = virQEMUDriverGetConfig(driver);
VIR_AUTOCLOSE directFd = -1;
int directFlag = 0;
bool needUnlink = false;
int ret;
/* mapped-ram does not support directIO */
/* When using directio with mapped-ram, qemu needs two fds. One with
* O_DIRECT set writing the memory, and another without it set for
* writing small bits of unaligned state. */
if ((flags & VIR_DOMAIN_SAVE_BYPASS_CACHE)) {
virReportError(VIR_ERR_OPERATION_FAILED, "%s",
_("bypass cache unsupported by this system"));
return -1;
directFlag = virFileDirectFdFlag();
if (directFlag < 0) {
virReportError(VIR_ERR_OPERATION_FAILED, "%s",
_("bypass cache unsupported by this system"));
return -1;
}
directFd = virQEMUFileOpenAs(cfg->user, cfg->group, false, path,
O_WRONLY | directFlag, &needUnlink);
if (directFd < 0)
return -1;
if (qemuSecuritySetImageFDLabel(driver->securityManager, vm->def, directFd) < 0)
return -1;
}
if (qemuSecuritySetImageFDLabel(driver->securityManager, vm->def, *fd) < 0)
@ -7202,7 +7221,7 @@ qemuMigrationSrcToSparseFile(virQEMUDriver *driver,
if (qemuDomainObjEnterMonitorAsync(vm, asyncJob) < 0)
return -1;
ret = qemuMonitorMigrateToFdSet(vm, 0, fd);
ret = qemuMonitorMigrateToFdSet(vm, 0, fd, &directFd);
qemuDomainObjExitMonitor(vm);
return ret;
}
@ -7211,6 +7230,7 @@ qemuMigrationSrcToSparseFile(virQEMUDriver *driver,
/* Helper function called while vm is active. */
int
qemuMigrationSrcToFile(virQEMUDriver *driver, virDomainObj *vm,
const char *path,
int *fd,
virCommand *compressor,
qemuMigrationParams *migParams,
@ -7248,7 +7268,7 @@ qemuMigrationSrcToFile(virQEMUDriver *driver, virDomainObj *vm,
if (migParams &&
qemuMigrationParamsCapEnabled(migParams, QEMU_MIGRATION_CAP_MAPPED_RAM))
rc = qemuMigrationSrcToSparseFile(driver, vm, fd, flags, asyncJob);
rc = qemuMigrationSrcToSparseFile(driver, vm, path, fd, flags, asyncJob);
else
rc = qemuMigrationSrcToLegacyFile(driver, vm, *fd, compressor, asyncJob);

1
src/qemu/qemu_migration.h
View File

@ -238,6 +238,7 @@ qemuMigrationSrcIsAllowed(virDomainObj *vm,
int
qemuMigrationSrcToFile(virQEMUDriver *driver,
virDomainObj *vm,
const char *path,
int *fd,
virCommand *compressor,
qemuMigrationParams *migParams,

11
src/qemu/qemu_migration_params.c
View File

@ -130,6 +130,7 @@ VIR_ENUM_IMPL(qemuMigrationParam,
"multifd-zlib-level",
"multifd-zstd-level",
"avail-switchover-bandwidth",
"direct-io",
);
typedef struct _qemuMigrationParamsAlwaysOnItem qemuMigrationParamsAlwaysOnItem;
@ -328,6 +329,9 @@ static const qemuMigrationParamInfoItem qemuMigrationParamInfo[] = {
[QEMU_MIGRATION_PARAM_AVAIL_SWITCHOVER_BANDWIDTH] = {
.type = QEMU_MIGRATION_PARAM_TYPE_ULL,
},
[QEMU_MIGRATION_PARAM_DIRECT_IO] = {
.type = QEMU_MIGRATION_PARAM_TYPE_BOOL,
},
};
G_STATIC_ASSERT(G_N_ELEMENTS(qemuMigrationParamInfo) == QEMU_MIGRATION_PARAM_LAST);
@ -793,7 +797,7 @@ qemuMigrationParamsFromFlags(virTypedParameterPtr params,
qemuMigrationParams *
qemuMigrationParamsForSave(bool sparse)
qemuMigrationParamsForSave(bool sparse, unsigned int flags)
{
g_autoptr(qemuMigrationParams) saveParams = NULL;
@ -807,6 +811,11 @@ qemuMigrationParamsForSave(bool sparse)
return NULL;
saveParams->params[QEMU_MIGRATION_PARAM_MULTIFD_CHANNELS].value.i = 1;
saveParams->params[QEMU_MIGRATION_PARAM_MULTIFD_CHANNELS].set = true;
if (flags & VIR_DOMAIN_SAVE_BYPASS_CACHE) {
saveParams->params[QEMU_MIGRATION_PARAM_DIRECT_IO].value.b = true;
saveParams->params[QEMU_MIGRATION_PARAM_DIRECT_IO].set = true;
}
}
return g_steal_pointer(&saveParams);

3
src/qemu/qemu_migration_params.h
View File

@ -66,6 +66,7 @@ typedef enum {
QEMU_MIGRATION_PARAM_MULTIFD_ZLIB_LEVEL,
QEMU_MIGRATION_PARAM_MULTIFD_ZSTD_LEVEL,
QEMU_MIGRATION_PARAM_AVAIL_SWITCHOVER_BANDWIDTH,
QEMU_MIGRATION_PARAM_DIRECT_IO,
QEMU_MIGRATION_PARAM_LAST
} qemuMigrationParam;
@ -88,7 +89,7 @@ qemuMigrationParamsFromFlags(virTypedParameterPtr params,
qemuMigrationParty party);
qemuMigrationParams *
qemuMigrationParamsForSave(bool sparse);
qemuMigrationParamsForSave(bool sparse, unsigned int flags);
int
qemuMigrationParamsDump(qemuMigrationParams *migParams,

7
src/qemu/qemu_monitor.c
View File

@ -2233,7 +2233,8 @@ qemuMonitorMigrateToFd(qemuMonitor *mon,
int
qemuMonitorMigrateToFdSet(virDomainObj *vm,
unsigned int flags,
int *fd)
int *fd,
int *directFd)
{
qemuDomainObjPrivate *priv = vm->privateData;
qemuMonitor *mon = priv->mon;
@ -2242,7 +2243,7 @@ qemuMonitorMigrateToFdSet(virDomainObj *vm,
g_autofree char *uri = NULL;
int ret;
VIR_DEBUG("fd=%d flags=0x%x", *fd, flags);
VIR_DEBUG("fd=%d directFd=%d flags=0x%x", *fd, *directFd, flags);
QEMU_CHECK_MONITOR(mon);
@ -2254,6 +2255,8 @@ qemuMonitorMigrateToFdSet(virDomainObj *vm,
fdPassMigrate = qemuFDPassNew("libvirt-outgoing-migrate", priv);
qemuFDPassAddFD(fdPassMigrate, fd, "-fd");
if (*directFd != -1)
qemuFDPassAddFD(fdPassMigrate, directFd, "-directio-fd");
qemuFDPassTransferMonitor(fdPassMigrate, mon);
uri = g_strdup_printf("file:%s,offset=%#lx",

3
src/qemu/qemu_monitor.h
View File

@ -861,7 +861,8 @@ int qemuMonitorMigrateToFd(qemuMonitor *mon,
int qemuMonitorMigrateToFdSet(virDomainObj *vm,
unsigned int flags,
int *fd);
int *fd,
int *directFd);
int qemuMonitorMigrateToHost(qemuMonitor *mon,
unsigned int flags,

2
src/qemu/qemu_saveimage.c
View File

@ -501,7 +501,7 @@ qemuSaveImageCreate(virQEMUDriver *driver,
goto cleanup;
/* Perform the migration */
if (qemuMigrationSrcToFile(driver, vm, &fd, compressor, saveParams, flags, asyncJob) < 0)
if (qemuMigrationSrcToFile(driver, vm, path, &fd, compressor, saveParams, flags, asyncJob) < 0)
goto cleanup;
/* Touch up file header to mark image complete. */