[libvirt] [PATCH 3/4] Fix QEMU save/restore with block devices
Daniel P. Berrange
berrange at redhat.com
Thu Apr 22 11:43:28 UTC 2010
The save process was relying on use of the shell >> append
operator to ensure the save data was placed after the libvirt
header + XML. This doesn't work for block devices though.
Replace this code with use of 'dd' and its 'seek' parameter.
This means that we need to pad the header + XML out to a
multiple of dd block size (in this case we choose 512).
The qemuMonitorMigateToCommand() monitor API is used for both
save/coredump, and migration via UNIX socket. We can't simply
switch this to use 'dd' since this causes problems with the
migration usage. Thus, create a dedicated qemuMonitorMigateToFile
which can accept an filename + offset, and remove the filename
from the current qemuMonitorMigateToCommand() API
* src/qemu/qemu_driver.c: Switch to qemuMonitorMigateToFile
for save and core dump
* src/qemu/qemu_monitor.c, src/qemu/qemu_monitor.h,
src/qemu/qemu_monitor_json.c, src/qemu/qemu_monitor_json.h,
src/qemu/qemu_monitor_text.c, src/qemu/qemu_monitor_text.h: Create
a new qemuMonitorMigateToFile, separate from the existing
qemuMonitorMigateToCommand to allow handling file offsets
---
src/qemu/qemu_driver.c | 190 +++++++++++++++++++++++++-----------------
src/qemu/qemu_monitor.c | 35 +++++++--
src/qemu/qemu_monitor.h | 11 ++-
src/qemu/qemu_monitor_json.c | 37 ++++++++-
src/qemu/qemu_monitor_json.h | 9 ++-
src/qemu/qemu_monitor_text.c | 37 ++++++++-
src/qemu/qemu_monitor_text.h | 9 ++-
7 files changed, 232 insertions(+), 96 deletions(-)
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 41a516c..09b6493 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -4789,6 +4789,7 @@ static int qemudDomainSaveFlag(virDomainPtr dom, const char *path,
qemuDomainObjPrivatePtr priv;
struct stat sb;
int is_reg = 0;
+ unsigned long long offset;
memset(&header, 0, sizeof(header));
memcpy(header.magic, QEMUD_SAVE_MAGIC, sizeof(header.magic));
@@ -4862,104 +4863,137 @@ static int qemudDomainSaveFlag(virDomainPtr dom, const char *path,
hdata.path = path;
hdata.xml = xml;
hdata.header = &header;
+ offset = sizeof(header) + header.xml_len;
+
+ /* Due to way we append QEMU state on our header with dd,
+ * we need to ensure there's a 512 byte boundary. Unfortunately
+ * we don't have an explicit offset in the header, so we fake
+ * it by padding the XML string with NULLs */
+ if (offset % QEMU_MONITOR_MIGRATE_TO_FILE_BS) {
+ unsigned long long pad =
+ QEMU_MONITOR_MIGRATE_TO_FILE_BS -
+ (offset % QEMU_MONITOR_MIGRATE_TO_FILE_BS);
+
+ if (VIR_REALLOC_N(xml, header.xml_len + pad) < 0) {
+ virReportOOMError();
+ goto endjob;
+ }
+ memset(xml + header.xml_len, 0, pad);
+ offset += pad;
+ header.xml_len += pad;
+ }
/* Write header to file, followed by XML */
/* First try creating the file as root */
- if (is_reg &&
- (rc = virFileOperation(path, O_CREAT|O_TRUNC|O_WRONLY,
- S_IRUSR|S_IWUSR,
- getuid(), getgid(),
- qemudDomainSaveFileOpHook, &hdata,
- 0)) != 0) {
-
- /* If we failed as root, and the error was permission-denied
- (EACCES), assume it's on a network-connected share where
- root access is restricted (eg, root-squashed NFS). If the
- qemu user (driver->user) is non-root, just set a flag to
- bypass security driver shenanigans, and retry the operation
- after doing setuid to qemu user */
-
- if ((rc != EACCES) ||
- driver->user == getuid()) {
- virReportSystemError(rc, _("Failed to create domain save file '%s'"),
- path);
+ if (!is_reg) {
+ int fd = open(path, O_WRONLY | O_TRUNC);
+ if (fd < 0) {
+ virReportSystemError(errno, _("unable to open %s"), path);
goto endjob;
}
-
-#ifdef __linux__
- /* On Linux we can also verify the FS-type of the directory. */
- char *dirpath, *p;
- struct statfs st;
- int statfs_ret;
-
- if ((dirpath = strdup(path)) == NULL) {
- virReportOOMError();
+ if ((rc = qemudDomainSaveFileOpHook(fd, &hdata)) != 0) {
+ close(fd);
+ goto endjob;
+ }
+ if (close(fd) < 0) {
+ virReportSystemError(errno, _("unable to close %s"), path);
goto endjob;
}
+ } else {
+ if ((rc = virFileOperation(path, O_CREAT|O_TRUNC|O_WRONLY,
+ S_IRUSR|S_IWUSR,
+ getuid(), getgid(),
+ qemudDomainSaveFileOpHook, &hdata,
+ 0)) != 0) {
+ /* If we failed as root, and the error was permission-denied
+ (EACCES), assume it's on a network-connected share where
+ root access is restricted (eg, root-squashed NFS). If the
+ qemu user (driver->user) is non-root, just set a flag to
+ bypass security driver shenanigans, and retry the operation
+ after doing setuid to qemu user */
+
+ if ((rc != EACCES) ||
+ driver->user == getuid()) {
+ virReportSystemError(rc, _("Failed to create domain save file '%s'"),
+ path);
+ goto endjob;
+ }
- do {
- // Try less and less of the path until we get to a
- // directory we can stat. Even if we don't have 'x'
- // permission on any directory in the path on the NFS
- // server (assuming it's NFS), we will be able to stat the
- // mount point, and that will properly tell us if the
- // fstype is NFS.
+#ifdef __linux__
+ /* On Linux we can also verify the FS-type of the directory. */
+ char *dirpath, *p;
+ struct statfs st;
+ int statfs_ret;
- if ((p = strrchr(dirpath, '/')) == NULL) {
- qemuReportError(VIR_ERR_INVALID_ARG,
- _("Invalid relative path '%s' for domain save file"),
- path);
- VIR_FREE(dirpath);
+ if ((dirpath = strdup(path)) == NULL) {
+ virReportOOMError();
goto endjob;
}
- if (p == dirpath)
- *(p+1) = '\0';
- else
- *p = '\0';
+ do {
+ // Try less and less of the path until we get to a
+ // directory we can stat. Even if we don't have 'x'
+ // permission on any directory in the path on the NFS
+ // server (assuming it's NFS), we will be able to stat the
+ // mount point, and that will properly tell us if the
+ // fstype is NFS.
+
+ if ((p = strrchr(dirpath, '/')) == NULL) {
+ qemuReportError(VIR_ERR_INVALID_ARG,
+ _("Invalid relative path '%s' for domain save file"),
+ path);
+ VIR_FREE(dirpath);
+ goto endjob;
+ }
- statfs_ret = statfs(dirpath, &st);
+ if (p == dirpath)
+ *(p+1) = '\0';
+ else
+ *p = '\0';
- } while ((statfs_ret == -1) && (p != dirpath));
+ statfs_ret = statfs(dirpath, &st);
- if (statfs_ret == -1) {
- virReportSystemError(errno,
- _("Failed to create domain save file '%s'"
- " statfs of all elements of path failed."),
- path);
- VIR_FREE(dirpath);
- goto endjob;
- }
+ } while ((statfs_ret == -1) && (p != dirpath));
- if (st.f_type != NFS_SUPER_MAGIC) {
- virReportSystemError(rc,
- _("Failed to create domain save file '%s'"
- " (fstype of '%s' is 0x%X"),
- path, dirpath, (unsigned int) st.f_type);
+ if (statfs_ret == -1) {
+ virReportSystemError(errno,
+ _("Failed to create domain save file '%s'"
+ " statfs of all elements of path failed."),
+ path);
+ VIR_FREE(dirpath);
+ goto endjob;
+ }
+
+ if (st.f_type != NFS_SUPER_MAGIC) {
+ virReportSystemError(rc,
+ _("Failed to create domain save file '%s'"
+ " (fstype of '%s' is 0x%X"),
+ path, dirpath, (unsigned int) st.f_type);
+ VIR_FREE(dirpath);
+ goto endjob;
+ }
VIR_FREE(dirpath);
- goto endjob;
- }
- VIR_FREE(dirpath);
#endif
- /* Retry creating the file as driver->user */
+ /* Retry creating the file as driver->user */
- if ((rc = virFileOperation(path, O_CREAT|O_TRUNC|O_WRONLY,
- S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP,
- driver->user, driver->group,
- qemudDomainSaveFileOpHook, &hdata,
- VIR_FILE_OP_AS_UID)) != 0) {
- virReportSystemError(rc, _("Error from child process creating '%s'"),
+ if ((rc = virFileOperation(path, O_CREAT|O_TRUNC|O_WRONLY,
+ S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP,
+ driver->user, driver->group,
+ qemudDomainSaveFileOpHook, &hdata,
+ VIR_FILE_OP_AS_UID)) != 0) {
+ virReportSystemError(rc, _("Error from child process creating '%s'"),
path);
- goto endjob;
- }
+ goto endjob;
+ }
- /* Since we had to setuid to create the file, and the fstype
- is NFS, we assume it's a root-squashing NFS share, and that
- the security driver stuff would have failed anyway */
+ /* Since we had to setuid to create the file, and the fstype
+ is NFS, we assume it's a root-squashing NFS share, and that
+ the security driver stuff would have failed anyway */
- bypassSecurityDriver = 1;
+ bypassSecurityDriver = 1;
+ }
}
@@ -4972,7 +5006,7 @@ static int qemudDomainSaveFlag(virDomainPtr dom, const char *path,
if (header.compressed == QEMUD_SAVE_FORMAT_RAW) {
const char *args[] = { "cat", NULL };
qemuDomainObjEnterMonitorWithDriver(driver, vm);
- rc = qemuMonitorMigrateToCommand(priv->mon, 1, args, path);
+ rc = qemuMonitorMigrateToFile(priv->mon, 1, args, path, offset);
qemuDomainObjExitMonitorWithDriver(driver, vm);
} else {
const char *prog = qemudSaveCompressionTypeToString(header.compressed);
@@ -4982,7 +5016,7 @@ static int qemudDomainSaveFlag(virDomainPtr dom, const char *path,
NULL
};
qemuDomainObjEnterMonitorWithDriver(driver, vm);
- rc = qemuMonitorMigrateToCommand(priv->mon, 1, args, path);
+ rc = qemuMonitorMigrateToFile(priv->mon, 1, args, path, offset);
qemuDomainObjExitMonitorWithDriver(driver, vm);
}
@@ -5275,7 +5309,7 @@ static int qemudDomainCoreDump(virDomainPtr dom,
}
qemuDomainObjEnterMonitor(vm);
- ret = qemuMonitorMigrateToCommand(priv->mon, 1, args, path);
+ ret = qemuMonitorMigrateToFile(priv->mon, 1, args, path, 0);
qemuDomainObjExitMonitor(vm);
if (ret < 0)
@@ -10043,7 +10077,7 @@ static int doTunnelMigrate(virDomainPtr dom,
internalret = qemuMonitorMigrateToUnix(priv->mon, 1, unixfile);
else if (qemuCmdFlags & QEMUD_CMD_FLAG_MIGRATE_QEMU_EXEC) {
const char *args[] = { "nc", "-U", unixfile, NULL };
- internalret = qemuMonitorMigrateToCommand(priv->mon, 1, args, "/dev/null");
+ internalret = qemuMonitorMigrateToCommand(priv->mon, 1, args);
} else {
internalret = -1;
}
diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c
index 32c3cd5..800f3c5 100644
--- a/src/qemu/qemu_monitor.c
+++ b/src/qemu/qemu_monitor.c
@@ -1202,17 +1202,40 @@ int qemuMonitorMigrateToHost(qemuMonitorPtr mon,
int qemuMonitorMigrateToCommand(qemuMonitorPtr mon,
int background,
- const char * const *argv,
- const char *target)
+ const char * const *argv)
{
int ret;
- DEBUG("mon=%p, fd=%d argv=%p target=%s",
- mon, mon->fd, argv, target);
+ DEBUG("mon=%p, fd=%d argv=%p",
+ mon, mon->fd, argv);
if (mon->json)
- ret = qemuMonitorJSONMigrateToCommand(mon, background, argv, target);
+ ret = qemuMonitorJSONMigrateToCommand(mon, background, argv);
else
- ret = qemuMonitorTextMigrateToCommand(mon, background, argv, target);
+ ret = qemuMonitorTextMigrateToCommand(mon, background, argv);
+ return ret;
+}
+
+int qemuMonitorMigrateToFile(qemuMonitorPtr mon,
+ int background,
+ const char * const *argv,
+ const char *target,
+ unsigned long long offset)
+{
+ int ret;
+ DEBUG("mon=%p, fd=%d argv=%p target=%s offset=%llu",
+ mon, mon->fd, argv, target, offset);
+
+ if (offset % QEMU_MONITOR_MIGRATE_TO_FILE_BS) {
+ qemuReportError(VIR_ERR_INTERNAL_ERROR,
+ _("file offset must be a multiple of %llu"),
+ QEMU_MONITOR_MIGRATE_TO_FILE_BS);
+ return -1;
+ }
+
+ if (mon->json)
+ ret = qemuMonitorJSONMigrateToFile(mon, background, argv, target, offset);
+ else
+ ret = qemuMonitorTextMigrateToFile(mon, background, argv, target, offset);
return ret;
}
diff --git a/src/qemu/qemu_monitor.h b/src/qemu/qemu_monitor.h
index a0f198b..a190ed7 100644
--- a/src/qemu/qemu_monitor.h
+++ b/src/qemu/qemu_monitor.h
@@ -251,8 +251,15 @@ int qemuMonitorMigrateToHost(qemuMonitorPtr mon,
int qemuMonitorMigrateToCommand(qemuMonitorPtr mon,
int background,
- const char * const *argv,
- const char *target);
+ const char * const *argv);
+
+#define QEMU_MONITOR_MIGRATE_TO_FILE_BS 512llu
+
+int qemuMonitorMigrateToFile(qemuMonitorPtr mon,
+ int background,
+ const char * const *argv,
+ const char *target,
+ unsigned long long offset);
int qemuMonitorMigrateToUnix(qemuMonitorPtr mon,
int background,
diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c
index b0773ab..3e61b12 100644
--- a/src/qemu/qemu_monitor_json.c
+++ b/src/qemu/qemu_monitor_json.c
@@ -1652,8 +1652,36 @@ int qemuMonitorJSONMigrateToHost(qemuMonitorPtr mon,
int qemuMonitorJSONMigrateToCommand(qemuMonitorPtr mon,
int background,
- const char * const *argv,
- const char *target)
+ const char * const *argv)
+{
+ char *argstr;
+ char *dest = NULL;
+ int ret = -1;
+
+ argstr = virArgvToString(argv);
+ if (!argstr) {
+ virReportOOMError();
+ goto cleanup;
+ }
+
+ if (virAsprintf(&dest, "exec:%s", argstr) < 0) {
+ virReportOOMError();
+ goto cleanup;
+ }
+
+ ret = qemuMonitorJSONMigrate(mon, background, dest);
+
+cleanup:
+ VIR_FREE(argstr);
+ VIR_FREE(dest);
+ return ret;
+}
+
+int qemuMonitorJSONMigrateToFile(qemuMonitorPtr mon,
+ int background,
+ const char * const *argv,
+ const char *target,
+ unsigned long long offset)
{
char *argstr;
char *dest = NULL;
@@ -1673,7 +1701,10 @@ int qemuMonitorJSONMigrateToCommand(qemuMonitorPtr mon,
goto cleanup;
}
- if (virAsprintf(&dest, "exec:%s >>%s 2>/dev/null", argstr, safe_target) < 0) {
+ if (virAsprintf(&dest, "exec:%s | dd of=%s bs=%llu seek=%llu",
+ argstr, safe_target,
+ QEMU_MONITOR_MIGRATE_TO_FILE_BS,
+ offset / QEMU_MONITOR_MIGRATE_TO_FILE_BS) < 0) {
virReportOOMError();
goto cleanup;
}
diff --git a/src/qemu/qemu_monitor_json.h b/src/qemu/qemu_monitor_json.h
index 157a5c0..4dcb3e0 100644
--- a/src/qemu/qemu_monitor_json.h
+++ b/src/qemu/qemu_monitor_json.h
@@ -104,8 +104,13 @@ int qemuMonitorJSONMigrateToHost(qemuMonitorPtr mon,
int qemuMonitorJSONMigrateToCommand(qemuMonitorPtr mon,
int background,
- const char * const *argv,
- const char *target);
+ const char * const *argv);
+
+int qemuMonitorJSONMigrateToFile(qemuMonitorPtr mon,
+ int background,
+ const char * const *argv,
+ const char *target,
+ unsigned long long offset);
int qemuMonitorJSONMigrateToUnix(qemuMonitorPtr mon,
int background,
diff --git a/src/qemu/qemu_monitor_text.c b/src/qemu/qemu_monitor_text.c
index 6490ea6..937f5b1 100644
--- a/src/qemu/qemu_monitor_text.c
+++ b/src/qemu/qemu_monitor_text.c
@@ -1202,8 +1202,36 @@ int qemuMonitorTextMigrateToHost(qemuMonitorPtr mon,
int qemuMonitorTextMigrateToCommand(qemuMonitorPtr mon,
int background,
- const char * const *argv,
- const char *target)
+ const char * const *argv)
+{
+ char *argstr;
+ char *dest = NULL;
+ int ret = -1;
+
+ argstr = virArgvToString(argv);
+ if (!argstr) {
+ virReportOOMError();
+ goto cleanup;
+ }
+
+ if (virAsprintf(&dest, "exec:%s", argstr) < 0) {
+ virReportOOMError();
+ goto cleanup;
+ }
+
+ ret = qemuMonitorTextMigrate(mon, background, dest);
+
+cleanup:
+ VIR_FREE(argstr);
+ VIR_FREE(dest);
+ return ret;
+}
+
+int qemuMonitorTextMigrateToFile(qemuMonitorPtr mon,
+ int background,
+ const char * const *argv,
+ const char *target,
+ unsigned long long offset)
{
char *argstr;
char *dest = NULL;
@@ -1223,7 +1251,10 @@ int qemuMonitorTextMigrateToCommand(qemuMonitorPtr mon,
goto cleanup;
}
- if (virAsprintf(&dest, "exec:%s >>%s 2>/dev/null", argstr, safe_target) < 0) {
+ if (virAsprintf(&dest, "exec:%s | dd of=%s bs=%llu seek=%llu",
+ argstr, safe_target,
+ QEMU_MONITOR_MIGRATE_TO_FILE_BS,
+ offset / QEMU_MONITOR_MIGRATE_TO_FILE_BS) < 0) {
virReportOOMError();
goto cleanup;
}
diff --git a/src/qemu/qemu_monitor_text.h b/src/qemu/qemu_monitor_text.h
index c80957e..25be828 100644
--- a/src/qemu/qemu_monitor_text.h
+++ b/src/qemu/qemu_monitor_text.h
@@ -99,8 +99,13 @@ int qemuMonitorTextMigrateToHost(qemuMonitorPtr mon,
int qemuMonitorTextMigrateToCommand(qemuMonitorPtr mon,
int background,
- const char * const *argv,
- const char *target);
+ const char * const *argv);
+
+int qemuMonitorTextMigrateToFile(qemuMonitorPtr mon,
+ int background,
+ const char * const *argv,
+ const char *target,
+ unsigned long long offset);
int qemuMonitorTextMigrateToUnix(qemuMonitorPtr mon,
int background,
--
1.6.5.2
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