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mimic: krbd: fix rbd map hang due to udev return subsystem unordered #30176

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merged 1 commit into from Oct 8, 2019
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mimic: krbd: fix rbd map hang due to udev return subsystem unordered #30176

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63 changes: 39 additions & 24 deletions src/krbd.cc
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Expand Up @@ -184,6 +184,8 @@ static int wait_for_udev_add(struct udev_monitor *mon, const char *pool,
string *pname)
{
struct udev_device *bus_dev = nullptr;
std::vector<struct udev_device*> block_dev_vec;
int r;

/*
* Catch /sys/devices/rbd/<id>/ and wait for the corresponding
Expand All @@ -193,16 +195,16 @@ static int wait_for_udev_add(struct udev_monitor *mon, const char *pool,
for (;;) {
struct pollfd fds[1];
struct udev_device *dev;
int r;

fds[0].fd = udev_monitor_get_fd(mon);
fds[0].events = POLLIN;
r = poll(fds, 1, POLL_TIMEOUT);
if (r < 0)
return -errno;

if (r == 0)
return -ETIMEDOUT;
if (r > 0) {
r = 0;
} else {
r = (r == 0) ? -ETIMEDOUT : -errno;
break;
}

dev = udev_monitor_receive_device(mon);
if (!dev)
Expand All @@ -211,8 +213,8 @@ static int wait_for_udev_add(struct udev_monitor *mon, const char *pool,
if (strcmp(udev_device_get_action(dev), "add") != 0)
goto next;

if (!bus_dev) {
if (strcmp(udev_device_get_subsystem(dev), "rbd") == 0) {
if (strcmp(udev_device_get_subsystem(dev), "rbd") == 0) {
if (!bus_dev) {
const char *this_pool = udev_device_get_sysattr_value(dev, "pool");
const char *this_image = udev_device_get_sysattr_value(dev, "name");
const char *this_snap = udev_device_get_sysattr_value(dev,
Expand All @@ -222,37 +224,50 @@ static int wait_for_udev_add(struct udev_monitor *mon, const char *pool,
this_image && strcmp(this_image, image) == 0 &&
this_snap && strcmp(this_snap, snap) == 0) {
bus_dev = dev;
continue;
goto check;
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This conditional block is where I had to resolve conflicts manually, and I'm not super confident the conflict resolution is correct.

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This looks fine.

}
}
} else {
if (strcmp(udev_device_get_subsystem(dev), "block") == 0) {
const char *major = udev_device_get_sysattr_value(bus_dev, "major");
const char *minor = udev_device_get_sysattr_value(bus_dev, "minor");
const char *this_major = udev_device_get_property_value(dev, "MAJOR");
const char *this_minor = udev_device_get_property_value(dev, "MINOR");
} else if (strcmp(udev_device_get_subsystem(dev), "block") == 0) {
block_dev_vec.push_back(dev);
goto check;
}

next:
udev_device_unref(dev);
continue;

check:
if (bus_dev && !block_dev_vec.empty()) {
const char *major = udev_device_get_sysattr_value(bus_dev, "major");
const char *minor = udev_device_get_sysattr_value(bus_dev, "minor");
assert(!minor ^ have_minor_attr());

assert(!minor ^ have_minor_attr());
for (auto p : block_dev_vec) {
const char *this_major = udev_device_get_property_value(p, "MAJOR");
const char *this_minor = udev_device_get_property_value(p, "MINOR");

if (strcmp(this_major, major) == 0 &&
(!minor || strcmp(this_minor, minor) == 0)) {
string name = get_kernel_rbd_name(udev_device_get_sysname(bus_dev));

assert(strcmp(udev_device_get_devnode(dev), name.c_str()) == 0);
assert(strcmp(udev_device_get_devnode(p), name.c_str()) == 0);
*pname = name;

udev_device_unref(dev);
udev_device_unref(bus_dev);
break;
goto done;
}
}
}
}

next:
udev_device_unref(dev);
done:
if (bus_dev) {
udev_device_unref(bus_dev);
}

for (auto p : block_dev_vec) {
udev_device_unref(p);
}

return 0;
return r;
}

static int do_map(struct udev *udev, const char *pool, const char *image,
Expand Down