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Merge remote-tracking branch 'mdroth/qga-pull-4-27-12' into staging

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* mdroth/qga-pull-4-27-12:
  qemu-ga: persist tracking of fsfreeze state via filesystem
  qemu-ga: add a whitelist for fsfreeze-safe commands
  qemu-ga: improve recovery options for fsfreeze
This commit is contained in:
Anthony Liguori 2012-05-01 18:44:03 -05:00
commit 75e4e8475b
6 changed files with 409 additions and 138 deletions
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170
qga/commands-posix.c
View file

@ -316,44 +316,40 @@ static void guest_file_init(void)
#if defined(CONFIG_FSFREEZE)
static void disable_logging(void)
{
ga_disable_logging(ga_state);
}
static void enable_logging(void)
{
ga_enable_logging(ga_state);
}
typedef struct GuestFsfreezeMount {
char *dirname;
char *devtype;
QTAILQ_ENTRY(GuestFsfreezeMount) next;
} GuestFsfreezeMount;
struct {
GuestFsfreezeStatus status;
QTAILQ_HEAD(, GuestFsfreezeMount) mount_list;
} guest_fsfreeze_state;
typedef QTAILQ_HEAD(, GuestFsfreezeMount) GuestFsfreezeMountList;
static void guest_fsfreeze_free_mount_list(GuestFsfreezeMountList *mounts)
{
GuestFsfreezeMount *mount, *temp;
if (!mounts) {
return;
}
QTAILQ_FOREACH_SAFE(mount, mounts, next, temp) {
QTAILQ_REMOVE(mounts, mount, next);
g_free(mount->dirname);
g_free(mount->devtype);
g_free(mount);
}
}
/*
* Walk the mount table and build a list of local file systems
*/
static int guest_fsfreeze_build_mount_list(void)
static int guest_fsfreeze_build_mount_list(GuestFsfreezeMountList *mounts)
{
struct mntent *ment;
GuestFsfreezeMount *mount, *temp;
GuestFsfreezeMount *mount;
char const *mtab = MOUNTED;
FILE *fp;
QTAILQ_FOREACH_SAFE(mount, &guest_fsfreeze_state.mount_list, next, temp) {
QTAILQ_REMOVE(&guest_fsfreeze_state.mount_list, mount, next);
g_free(mount->dirname);
g_free(mount->devtype);
g_free(mount);
}
fp = setmntent(mtab, "r");
if (!fp) {
g_warning("fsfreeze: unable to read mtab");
@ -377,7 +373,7 @@ static int guest_fsfreeze_build_mount_list(void)
mount->dirname = g_strdup(ment->mnt_dir);
mount->devtype = g_strdup(ment->mnt_type);
QTAILQ_INSERT_TAIL(&guest_fsfreeze_state.mount_list, mount, next);
QTAILQ_INSERT_TAIL(mounts, mount, next);
}
endmntent(fp);
@ -390,7 +386,11 @@ static int guest_fsfreeze_build_mount_list(void)
*/
GuestFsfreezeStatus qmp_guest_fsfreeze_status(Error **err)
{
return guest_fsfreeze_state.status;
if (ga_is_frozen(ga_state)) {
return GUEST_FSFREEZE_STATUS_FROZEN;
}
return GUEST_FSFREEZE_STATUS_THAWED;
}
/*
@ -400,61 +400,61 @@ GuestFsfreezeStatus qmp_guest_fsfreeze_status(Error **err)
int64_t qmp_guest_fsfreeze_freeze(Error **err)
{
int ret = 0, i = 0;
struct GuestFsfreezeMount *mount, *temp;
GuestFsfreezeMountList mounts;
struct GuestFsfreezeMount *mount;
int fd;
char err_msg[512];
slog("guest-fsfreeze called");
if (guest_fsfreeze_state.status == GUEST_FSFREEZE_STATUS_FROZEN) {
return 0;
}
ret = guest_fsfreeze_build_mount_list();
QTAILQ_INIT(&mounts);
ret = guest_fsfreeze_build_mount_list(&mounts);
if (ret < 0) {
return ret;
}
/* cannot risk guest agent blocking itself on a write in this state */
disable_logging();
ga_set_frozen(ga_state);
QTAILQ_FOREACH_SAFE(mount, &guest_fsfreeze_state.mount_list, next, temp) {
QTAILQ_FOREACH(mount, &mounts, next) {
fd = qemu_open(mount->dirname, O_RDONLY);
if (fd == -1) {
sprintf(err_msg, "failed to open %s, %s", mount->dirname, strerror(errno));
sprintf(err_msg, "failed to open %s, %s", mount->dirname,
strerror(errno));
error_set(err, QERR_QGA_COMMAND_FAILED, err_msg);
goto error;
}
/* we try to cull filesytems we know won't work in advance, but other
* filesytems may not implement fsfreeze for less obvious reasons.
* these will report EOPNOTSUPP, so we simply ignore them. when
* thawing, these filesystems will return an EINVAL instead, due to
* not being in a frozen state. Other filesystem-specific
* errors may result in EINVAL, however, so the user should check the
* number * of filesystems returned here against those returned by the
* thaw operation to determine whether everything completed
* successfully
* these will report EOPNOTSUPP. we simply ignore these when tallying
* the number of frozen filesystems.
*
* any other error means a failure to freeze a filesystem we
* expect to be freezable, so return an error in those cases
* and return system to thawed state.
*/
ret = ioctl(fd, FIFREEZE);
if (ret < 0 && errno != EOPNOTSUPP) {
sprintf(err_msg, "failed to freeze %s, %s", mount->dirname, strerror(errno));
error_set(err, QERR_QGA_COMMAND_FAILED, err_msg);
close(fd);
goto error;
if (ret == -1) {
if (errno != EOPNOTSUPP) {
sprintf(err_msg, "failed to freeze %s, %s",
mount->dirname, strerror(errno));
error_set(err, QERR_QGA_COMMAND_FAILED, err_msg);
close(fd);
goto error;
}
} else {
i++;
}
close(fd);
i++;
}
guest_fsfreeze_state.status = GUEST_FSFREEZE_STATUS_FROZEN;
guest_fsfreeze_free_mount_list(&mounts);
return i;
error:
if (i > 0) {
qmp_guest_fsfreeze_thaw(NULL);
}
guest_fsfreeze_free_mount_list(&mounts);
qmp_guest_fsfreeze_thaw(NULL);
return 0;
}
@ -464,47 +464,61 @@ error:
int64_t qmp_guest_fsfreeze_thaw(Error **err)
{
int ret;
GuestFsfreezeMount *mount, *temp;
int fd, i = 0;
bool has_error = false;
GuestFsfreezeMountList mounts;
GuestFsfreezeMount *mount;
int fd, i = 0, logged;
QTAILQ_FOREACH_SAFE(mount, &guest_fsfreeze_state.mount_list, next, temp) {
QTAILQ_INIT(&mounts);
ret = guest_fsfreeze_build_mount_list(&mounts);
if (ret) {
error_set(err, QERR_QGA_COMMAND_FAILED,
"failed to enumerate filesystems");
return 0;
}
QTAILQ_FOREACH(mount, &mounts, next) {
logged = false;
fd = qemu_open(mount->dirname, O_RDONLY);
if (fd == -1) {
has_error = true;
continue;
}
ret = ioctl(fd, FITHAW);
if (ret < 0 && errno != EOPNOTSUPP && errno != EINVAL) {
has_error = true;
close(fd);
continue;
}
/* we have no way of knowing whether a filesystem was actually unfrozen
* as a result of a successful call to FITHAW, only that if an error
* was returned the filesystem was *not* unfrozen by that particular
* call.
*
* since multiple preceeding FIFREEZEs require multiple calls to FITHAW
* to unfreeze, continuing issuing FITHAW until an error is returned,
* in which case either the filesystem is in an unfreezable state, or,
* more likely, it was thawed previously (and remains so afterward).
*
* also, since the most recent successful call is the one that did
* the actual unfreeze, we can use this to provide an accurate count
* of the number of filesystems unfrozen by guest-fsfreeze-thaw, which
* may * be useful for determining whether a filesystem was unfrozen
* during the freeze/thaw phase by a process other than qemu-ga.
*/
do {
ret = ioctl(fd, FITHAW);
if (ret == 0 && !logged) {
i++;
logged = true;
}
} while (ret == 0);
close(fd);
i++;
}
if (has_error) {
guest_fsfreeze_state.status = GUEST_FSFREEZE_STATUS_ERROR;
} else {
guest_fsfreeze_state.status = GUEST_FSFREEZE_STATUS_THAWED;
}
enable_logging();
ga_unset_frozen(ga_state);
guest_fsfreeze_free_mount_list(&mounts);
return i;
}
static void guest_fsfreeze_init(void)
{
guest_fsfreeze_state.status = GUEST_FSFREEZE_STATUS_THAWED;
QTAILQ_INIT(&guest_fsfreeze_state.mount_list);
}
static void guest_fsfreeze_cleanup(void)
{
int64_t ret;
Error *err = NULL;
if (guest_fsfreeze_state.status == GUEST_FSFREEZE_STATUS_FROZEN) {
if (ga_is_frozen(ga_state) == GUEST_FSFREEZE_STATUS_FROZEN) {
ret = qmp_guest_fsfreeze_thaw(&err);
if (ret < 0 || err) {
slog("failed to clean up frozen filesystems");
@ -933,7 +947,7 @@ int64_t qmp_guest_fsfreeze_thaw(Error **err)
void ga_command_state_init(GAState *s, GACommandState *cs)
{
#if defined(CONFIG_FSFREEZE)
ga_command_state_add(cs, guest_fsfreeze_init, guest_fsfreeze_cleanup);
ga_command_state_add(cs, NULL, guest_fsfreeze_cleanup);
#endif
ga_command_state_add(cs, guest_file_init, NULL);
}

3
qga/guest-agent-core.h
View file

@ -32,3 +32,6 @@ void ga_disable_logging(GAState *s);
void ga_enable_logging(GAState *s);
void slog(const gchar *fmt, ...);
void ga_set_response_delimited(GAState *s);
bool ga_is_frozen(GAState *s);
void ga_set_frozen(GAState *s);
void ga_unset_frozen(GAState *s);