Tools: hv: Reopen the devices if read() or write() returns errors
The state machine in the hv_utils driver can run out of order in some corner cases, e.g. if the kvp daemon doesn't call write() fast enough due to some reason, kvp_timeout_func() can run first and move the state to HVUTIL_READY; next, when kvp_on_msg() is called it returns -EINVAL since kvp_transaction.state is smaller than HVUTIL_USERSPACE_REQ; later, the daemon's write() gets an error -EINVAL, and the daemon will exit(). We can reproduce the issue by sending a SIGSTOP signal to the daemon, wait for 1 minute, and send a SIGCONT signal to the daemon: the daemon will exit() quickly. We can fix the issue by forcing a reset of the device (which means the daemon can close() and open() the device again) and doing extra necessary clean-up. Signed-off-by: Dexuan Cui <decui@microsoft.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Dexuan Cui
Sasha Levin
Родитель
3a6fb6c425
Коммит
9fc3c01a1f
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@ -80,6 +80,8 @@ static int hv_start_fcopy(struct hv_start_fcopy *smsg)
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error = 0;
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done:
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if (error)
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target_fname[0] = '\0';
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return error;
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}
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@ -108,15 +110,29 @@ static int hv_copy_data(struct hv_do_fcopy *cpmsg)
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return ret;
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}
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/*
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* Reset target_fname to "" in the two below functions for hibernation: if
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* the fcopy operation is aborted by hibernation, the daemon should remove the
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* partially-copied file; to achieve this, the hv_utils driver always fakes a
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* CANCEL_FCOPY message upon suspend, and later when the VM resumes back,
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* the daemon calls hv_copy_cancel() to remove the file; if a file is copied
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* successfully before suspend, hv_copy_finished() must reset target_fname to
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* avoid that the file can be incorrectly removed upon resume, since the faked
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* CANCEL_FCOPY message is spurious in this case.
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*/
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static int hv_copy_finished(void)
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{
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close(target_fd);
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target_fname[0] = '\0';
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return 0;
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}
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static int hv_copy_cancel(void)
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{
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close(target_fd);
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unlink(target_fname);
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if (strlen(target_fname) > 0) {
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unlink(target_fname);
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target_fname[0] = '\0';
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}
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return 0;
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}
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@ -131,7 +147,7 @@ void print_usage(char *argv[])
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int main(int argc, char *argv[])
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{
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int fcopy_fd;
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int fcopy_fd = -1;
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int error;
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int daemonize = 1, long_index = 0, opt;
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int version = FCOPY_CURRENT_VERSION;
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@ -141,7 +157,7 @@ int main(int argc, char *argv[])
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struct hv_do_fcopy copy;
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__u32 kernel_modver;
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} buffer = { };
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int in_handshake = 1;
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int in_handshake;
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static struct option long_options[] = {
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{"help", no_argument, 0, 'h' },
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@ -170,6 +186,12 @@ int main(int argc, char *argv[])
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openlog("HV_FCOPY", 0, LOG_USER);
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syslog(LOG_INFO, "starting; pid is:%d", getpid());
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reopen_fcopy_fd:
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if (fcopy_fd != -1)
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close(fcopy_fd);
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/* Remove any possible partially-copied file on error */
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hv_copy_cancel();
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in_handshake = 1;
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fcopy_fd = open("/dev/vmbus/hv_fcopy", O_RDWR);
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if (fcopy_fd < 0) {
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@ -196,7 +218,7 @@ int main(int argc, char *argv[])
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len = pread(fcopy_fd, &buffer, sizeof(buffer), 0);
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if (len < 0) {
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syslog(LOG_ERR, "pread failed: %s", strerror(errno));
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exit(EXIT_FAILURE);
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goto reopen_fcopy_fd;
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}
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if (in_handshake) {
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@ -231,9 +253,14 @@ int main(int argc, char *argv[])
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}
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/*
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* pwrite() may return an error due to the faked CANCEL_FCOPY
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* message upon hibernation. Ignore the error by resetting the
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* dev file, i.e. closing and re-opening it.
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*/
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if (pwrite(fcopy_fd, &error, sizeof(int), 0) != sizeof(int)) {
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syslog(LOG_ERR, "pwrite failed: %s", strerror(errno));
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exit(EXIT_FAILURE);
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goto reopen_fcopy_fd;
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}
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}
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}
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@ -76,7 +76,7 @@ enum {
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DNS
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};
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static int in_hand_shake = 1;
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static int in_hand_shake;
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static char *os_name = "";
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static char *os_major = "";
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@ -1360,7 +1360,7 @@ void print_usage(char *argv[])
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int main(int argc, char *argv[])
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{
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int kvp_fd, len;
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int kvp_fd = -1, len;
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int error;
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struct pollfd pfd;
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char *p;
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@ -1400,14 +1400,6 @@ int main(int argc, char *argv[])
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openlog("KVP", 0, LOG_USER);
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syslog(LOG_INFO, "KVP starting; pid is:%d", getpid());
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kvp_fd = open("/dev/vmbus/hv_kvp", O_RDWR | O_CLOEXEC);
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if (kvp_fd < 0) {
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syslog(LOG_ERR, "open /dev/vmbus/hv_kvp failed; error: %d %s",
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errno, strerror(errno));
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exit(EXIT_FAILURE);
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}
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/*
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* Retrieve OS release information.
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*/
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@ -1423,6 +1415,18 @@ int main(int argc, char *argv[])
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exit(EXIT_FAILURE);
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}
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reopen_kvp_fd:
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if (kvp_fd != -1)
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close(kvp_fd);
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in_hand_shake = 1;
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kvp_fd = open("/dev/vmbus/hv_kvp", O_RDWR | O_CLOEXEC);
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if (kvp_fd < 0) {
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syslog(LOG_ERR, "open /dev/vmbus/hv_kvp failed; error: %d %s",
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errno, strerror(errno));
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exit(EXIT_FAILURE);
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}
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/*
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* Register ourselves with the kernel.
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*/
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@ -1456,9 +1460,7 @@ int main(int argc, char *argv[])
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if (len != sizeof(struct hv_kvp_msg)) {
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syslog(LOG_ERR, "read failed; error:%d %s",
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errno, strerror(errno));
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close(kvp_fd);
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return EXIT_FAILURE;
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goto reopen_kvp_fd;
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}
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/*
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@ -1617,13 +1619,17 @@ int main(int argc, char *argv[])
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break;
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}
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/* Send the value back to the kernel. */
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/*
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* Send the value back to the kernel. Note: the write() may
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* return an error due to hibernation; we can ignore the error
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* by resetting the dev file, i.e. closing and re-opening it.
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*/
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kvp_done:
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len = write(kvp_fd, hv_msg, sizeof(struct hv_kvp_msg));
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if (len != sizeof(struct hv_kvp_msg)) {
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syslog(LOG_ERR, "write failed; error: %d %s", errno,
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strerror(errno));
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exit(EXIT_FAILURE);
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goto reopen_kvp_fd;
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}
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}
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@ -28,6 +28,8 @@
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#include <stdbool.h>
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#include <dirent.h>
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static bool fs_frozen;
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/* Don't use syslog() in the function since that can cause write to disk */
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static int vss_do_freeze(char *dir, unsigned int cmd)
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{
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@ -155,18 +157,27 @@ static int vss_operate(int operation)
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continue;
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}
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error |= vss_do_freeze(ent->mnt_dir, cmd);
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if (error && operation == VSS_OP_FREEZE)
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goto err;
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if (operation == VSS_OP_FREEZE) {
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if (error)
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goto err;
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fs_frozen = true;
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}
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}
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endmntent(mounts);
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if (root_seen) {
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error |= vss_do_freeze("/", cmd);
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if (error && operation == VSS_OP_FREEZE)
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goto err;
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if (operation == VSS_OP_FREEZE) {
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if (error)
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goto err;
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fs_frozen = true;
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}
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}
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if (operation == VSS_OP_THAW && !error)
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fs_frozen = false;
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goto out;
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err:
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save_errno = errno;
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@ -175,6 +186,7 @@ err:
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endmntent(mounts);
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}
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vss_operate(VSS_OP_THAW);
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fs_frozen = false;
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/* Call syslog after we thaw all filesystems */
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if (ent)
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syslog(LOG_ERR, "FREEZE of %s failed; error:%d %s",
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@ -196,13 +208,13 @@ void print_usage(char *argv[])
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int main(int argc, char *argv[])
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{
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int vss_fd, len;
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int vss_fd = -1, len;
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int error;
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struct pollfd pfd;
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int op;
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struct hv_vss_msg vss_msg[1];
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int daemonize = 1, long_index = 0, opt;
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int in_handshake = 1;
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int in_handshake;
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__u32 kernel_modver;
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static struct option long_options[] = {
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@ -232,6 +244,18 @@ int main(int argc, char *argv[])
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openlog("Hyper-V VSS", 0, LOG_USER);
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syslog(LOG_INFO, "VSS starting; pid is:%d", getpid());
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reopen_vss_fd:
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if (vss_fd != -1)
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close(vss_fd);
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if (fs_frozen) {
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if (vss_operate(VSS_OP_THAW) || fs_frozen) {
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syslog(LOG_ERR, "failed to thaw file system: err=%d",
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errno);
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exit(EXIT_FAILURE);
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}
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}
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in_handshake = 1;
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vss_fd = open("/dev/vmbus/hv_vss", O_RDWR);
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if (vss_fd < 0) {
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syslog(LOG_ERR, "open /dev/vmbus/hv_vss failed; error: %d %s",
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@ -284,8 +308,7 @@ int main(int argc, char *argv[])
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if (len != sizeof(struct hv_vss_msg)) {
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syslog(LOG_ERR, "read failed; error:%d %s",
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errno, strerror(errno));
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close(vss_fd);
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return EXIT_FAILURE;
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goto reopen_vss_fd;
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}
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op = vss_msg->vss_hdr.operation;
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@ -312,14 +335,18 @@ int main(int argc, char *argv[])
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default:
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syslog(LOG_ERR, "Illegal op:%d\n", op);
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}
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/*
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* The write() may return an error due to the faked VSS_OP_THAW
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* message upon hibernation. Ignore the error by resetting the
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* dev file, i.e. closing and re-opening it.
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*/
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vss_msg->error = error;
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len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
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if (len != sizeof(struct hv_vss_msg)) {
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syslog(LOG_ERR, "write failed; error: %d %s", errno,
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strerror(errno));
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if (op == VSS_OP_FREEZE)
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vss_operate(VSS_OP_THAW);
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goto reopen_vss_fd;
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}
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}
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