X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=src%2Fudev%2Fudevd.c;h=0f3f3f087a7a7616dec174d4b96ae857e4f5fbff;hp=f9ee36870bd3727dca1d01702050f76bef1c781b;hb=02ba8fb3357daf57f6120ac512fb464a4c623419;hpb=9ea28c55a2488e6cd4a44ac5786f12b71ad5bc9f diff --git a/src/udev/udevd.c b/src/udev/udevd.c index f9ee36870..0f3f3f087 100644 --- a/src/udev/udevd.c +++ b/src/udev/udevd.c @@ -31,12 +31,14 @@ #include #include #include +#include #include #include #include #include #include #include +#include #include #include #include @@ -45,6 +47,7 @@ #include #include "udev.h" +#include "udev-util.h" #include "sd-daemon.h" #include "cgroup-util.h" #include "dev-setup.h" @@ -265,7 +268,8 @@ static void worker_new(struct event *event) for (;;) { struct udev_event *udev_event; struct worker_message msg; - int err; + int fd_lock = -1; + int err = 0; log_debug("seq %llu running", udev_device_get_seqnum(dev)); udev_event = udev_event_new(dev); @@ -280,25 +284,63 @@ static void worker_new(struct event *event) if (exec_delay > 0) udev_event->exec_delay = exec_delay; + /* + * Take a "read lock" on the device node; this establishes + * a concept of device "ownership" to serialize device + * access. External processes holding a "write lock" will + * cause udev to skip the event handling; in the case udev + * acquired the lock, the external process will block until + * udev has finished its event handling. + */ + + /* + * since we make check - device seems unused - we try + * ioctl to deactivate - and device is found to be opened + * sure, you try to take a write lock + * if you get it udev is out + * if you can't get it, udev is busy + * we cannot deactivate openned device (as it is in-use) + * maybe we should just exclude dm from that thing entirely + * IMHO this sounds like a good plan for this moment + */ + if (streq_ptr("block", udev_device_get_subsystem(dev)) && + !startswith("dm-", udev_device_get_sysname(dev))) { + struct udev_device *d = dev; + + if (streq_ptr("partition", udev_device_get_devtype(d))) + d = udev_device_get_parent(d); + + if (d) { + fd_lock = open(udev_device_get_devnode(d), O_RDONLY|O_CLOEXEC|O_NOFOLLOW|O_NONBLOCK); + if (fd_lock >= 0 && flock(fd_lock, LOCK_SH|LOCK_NB) < 0) { + log_debug("Unable to flock(%s), skipping event handling: %m", udev_device_get_devnode(d)); + err = -EWOULDBLOCK; + fd_lock = safe_close(fd_lock); + goto skip; + } + } + } + /* apply rules, create node, symlinks */ - err = udev_event_execute_rules(udev_event, rules, &sigmask_orig); + udev_event_execute_rules(udev_event, rules, &sigmask_orig); - if (err == 0) - udev_event_execute_run(udev_event, &sigmask_orig); + udev_event_execute_run(udev_event, &sigmask_orig); /* apply/restore inotify watch */ - if (err == 0 && udev_event->inotify_watch) { + if (udev_event->inotify_watch) { udev_watch_begin(udev, dev); udev_device_update_db(dev); } + safe_close(fd_lock); + /* send processed event back to libudev listeners */ udev_monitor_send_device(worker_monitor, NULL, dev); +skip: /* send udevd the result of the event execution */ memzero(&msg, sizeof(struct worker_message)); - if (err != 0) - msg.exitcode = err; + msg.exitcode = err; msg.pid = getpid(); send(worker_watch[WRITE_END], &msg, sizeof(struct worker_message), 0); @@ -349,10 +391,8 @@ static void worker_new(struct event *event) } out: udev_device_unref(dev); - if (fd_signal >= 0) - close(fd_signal); - if (fd_ep >= 0) - close(fd_ep); + safe_close(fd_signal); + safe_close(fd_ep); close(fd_inotify); close(worker_watch[WRITE_END]); udev_rules_unref(rules); @@ -695,20 +735,123 @@ out: return udev_ctrl_connection_unref(ctrl_conn); } -/* read inotify messages */ +static int synthesize_change(struct udev_device *dev) { + char filename[UTIL_PATH_SIZE]; + int r; + + if (streq_ptr("block", udev_device_get_subsystem(dev)) && + streq_ptr("disk", udev_device_get_devtype(dev)) && + !startswith("dm-", udev_device_get_sysname(dev))) { + bool part_table_read = false; + bool has_partitions = false; + int fd; + struct udev *udev = udev_device_get_udev(dev); + _cleanup_udev_enumerate_unref_ struct udev_enumerate *e = NULL; + struct udev_list_entry *item; + + /* + * Try to re-read the partition table. This only succeeds if + * none of the devices is busy. The kernel returns 0 if no + * partition table is found, and we will not get an event for + * the disk. + */ + fd = open(udev_device_get_devnode(dev), O_RDONLY|O_CLOEXEC|O_NOFOLLOW|O_NONBLOCK); + if (fd >= 0) { + r = flock(fd, LOCK_EX|LOCK_NB); + if (r >= 0) + r = ioctl(fd, BLKRRPART, 0); + + close(fd); + if (r >= 0) + part_table_read = true; + } + + /* search for partitions */ + e = udev_enumerate_new(udev); + if (!e) + return -ENOMEM; + + r = udev_enumerate_add_match_parent(e, dev); + if (r < 0) + return r; + + r = udev_enumerate_add_match_subsystem(e, "block"); + if (r < 0) + return r; + + r = udev_enumerate_scan_devices(e); + + udev_list_entry_foreach(item, udev_enumerate_get_list_entry(e)) { + _cleanup_udev_device_unref_ struct udev_device *d = NULL; + + d = udev_device_new_from_syspath(udev, udev_list_entry_get_name(item)); + if (!d) + continue; + + if (!streq_ptr("partition", udev_device_get_devtype(d))) + continue; + + has_partitions = true; + break; + } + + /* + * We have partitions and re-read the table, the kernel already sent + * out a "change" event for the disk, and "remove/add" for all + * partitions. + */ + if (part_table_read && has_partitions) + return 0; + + /* + * We have partitions but re-reading the partition table did not + * work, synthesize "change" for the disk and all partitions. + */ + log_debug("device %s closed, synthesising 'change'", udev_device_get_devnode(dev)); + strscpyl(filename, sizeof(filename), udev_device_get_syspath(dev), "/uevent", NULL); + write_string_file(filename, "change"); + + udev_list_entry_foreach(item, udev_enumerate_get_list_entry(e)) { + _cleanup_udev_device_unref_ struct udev_device *d = NULL; + + d = udev_device_new_from_syspath(udev, udev_list_entry_get_name(item)); + if (!d) + continue; + + if (!streq_ptr("partition", udev_device_get_devtype(d))) + continue; + + log_debug("device %s closed, synthesising partition '%s' 'change'", + udev_device_get_devnode(dev), udev_device_get_devnode(d)); + strscpyl(filename, sizeof(filename), udev_device_get_syspath(d), "/uevent", NULL); + write_string_file(filename, "change"); + } + + return 0; + } + + log_debug("device %s closed, synthesising 'change'", udev_device_get_devnode(dev)); + strscpyl(filename, sizeof(filename), udev_device_get_syspath(dev), "/uevent", NULL); + write_string_file(filename, "change"); + + return 0; +} + static int handle_inotify(struct udev *udev) { int nbytes, pos; char *buf; struct inotify_event *ev; + int r; - if ((ioctl(fd_inotify, FIONREAD, &nbytes) < 0) || (nbytes <= 0)) - return 0; + r = ioctl(fd_inotify, FIONREAD, &nbytes); + if (r < 0 || nbytes <= 0) + return -errno; buf = malloc(nbytes); - if (buf == NULL) { + if (!buf) { log_error("error getting buffer for inotify"); - return -1; + return -ENOMEM; } nbytes = read(fd_inotify, buf, nbytes); @@ -718,27 +861,16 @@ static int handle_inotify(struct udev *udev) ev = (struct inotify_event *)(buf + pos); dev = udev_watch_lookup(udev, ev->wd); - if (dev != NULL) { - log_debug("inotify event: %x for %s", ev->mask, udev_device_get_devnode(dev)); - if (ev->mask & IN_CLOSE_WRITE) { - char filename[UTIL_PATH_SIZE]; - int fd; - - log_debug("device %s closed, synthesising 'change'", udev_device_get_devnode(dev)); - strscpyl(filename, sizeof(filename), udev_device_get_syspath(dev), "/uevent", NULL); - fd = open(filename, O_WRONLY|O_CLOEXEC); - if (fd >= 0) { - if (write(fd, "change", 6) < 0) - log_debug("error writing uevent: %m"); - close(fd); - } - } - if (ev->mask & IN_IGNORED) - udev_watch_end(udev, dev); + if (!dev) + continue; - udev_device_unref(dev); - } + log_debug("inotify event: %x for %s", ev->mask, udev_device_get_devnode(dev)); + if (ev->mask & IN_CLOSE_WRITE) + synthesize_change(dev); + else if (ev->mask & IN_IGNORED) + udev_watch_end(udev, dev); + udev_device_unref(dev); } free(buf);