In "find_multipaths smart" mode, use time stamps under
/dev/shm/multipath/find_multipaths to track waiting for multipath
siblings. When a path is first encountered and is "maybe" multipath, create
a file under /dev/shm, set its modification time to the expiry time of the
timer, and set the FIND_MULTIPATHS_WAIT_UNTIL variable. On later calls,
also set FIND_MULTIPATHS_WAIT_UNTIL to the expiry time (but don't change
the time stamp) if it's not expired yet, or 0 if it is expired. Set
FIND_MULTIPATHS_WAIT_UNTIL even if enough evidence becomes available to
decide if the path needs to be multipathed - this enables the udev rules to
detect that this is a device a timer has been started for, and stop it. By
using /dev/shm, we share information about "smart" timers between initrd
and root file system, and thus only calculate the timeout once.
Because we use major:minor to identify the devices in /dev/shm, and because
a removed device might be replaced by a different one with the same
major/minor number, add a rule to multipath.rules to remove the
find_multipaths marker on remove uevents.
Signed-off-by: Martin Wilck <mwilck@xxxxxxxx>
---
libmultipath/file.c | 2 +-
libmultipath/file.h | 1 +
multipath/main.c | 132 ++++++++++++++++++++++++++++++++++++++++++++++
multipath/multipath.rules | 4 +-
4 files changed, 137 insertions(+), 2 deletions(-)
diff --git a/libmultipath/file.c b/libmultipath/file.c
index d5165ec6..8727f160 100644
--- a/libmultipath/file.c
+++ b/libmultipath/file.c
@@ -36,7 +36,7 @@
* See the file COPYING included with this distribution for more details.
*/
-static int
+int
ensure_directories_exist(const char *str, mode_t dir_mode)
{
char *pathname;
diff --git a/libmultipath/file.h b/libmultipath/file.h
index 70bffa53..29520c74 100644
--- a/libmultipath/file.h
+++ b/libmultipath/file.h
@@ -6,6 +6,7 @@
#define _FILE_H
#define FILE_TIMEOUT 30
+int ensure_directories_exist(const char *str, mode_t dir_mode);
int open_file(const char *file, int *can_write, const char *header);
#endif /* _FILE_H */
diff --git a/multipath/main.c b/multipath/main.c
index f62e18a9..5d847f08 100644
--- a/multipath/main.c
+++ b/multipath/main.c
@@ -29,6 +29,7 @@
#include <ctype.h>
#include <libudev.h>
#include <syslog.h>
+#include <fcntl.h>
#include "checkers.h"
#include "prio.h"
@@ -60,6 +61,9 @@
#include "uxsock.h"
#include "mpath_cmd.h"
#include "foreign.h"
+#include "propsel.h"
+#include "time-util.h"
+#include "file.h"
int logsink;
struct udev *udev;
@@ -350,14 +354,142 @@ out:
return r;
}
+enum {
+ FIND_MULTIPATHS_WAIT_DONE = 0,
+ FIND_MULTIPATHS_WAITING = 1,
+ FIND_MULTIPATHS_ERROR = -1,
+ FIND_MULTIPATHS_NEVER = -2,
+};
+
+static const char shm_find_mp_dir[] = MULTIPATH_SHM_BASE "find_multipaths";
+static void close_fd(void *arg)
+{
+ close((long)arg);
+}
+
+/**
+ * find_multipaths_check_timeout(wwid, tmo)
+ * Helper for "find_multipaths smart"
+ *
+ * @param[in] pp: path to check / record
+ * @param[in] tmo: configured timeout for this WWID, or value <= 0 for checking
+ * @param[out] until: timestamp until we must wait, CLOCK_REALTIME, if return
+ * value is FIND_MULTIPATHS_WAITING
+ * @returns: FIND_MULTIPATHS_WAIT_DONE, if waiting has finished
+ * @returns: FIND_MULTIPATHS_ERROR, if internal error occurred
+ * @returns: FIND_MULTIPATHS_NEVER, if tmo is 0 and we didn't wait for this
+ * device
+ * @returns: FIND_MULTIPATHS_WAITING, if timeout hasn't expired
+ */
+static int find_multipaths_check_timeout(const struct path *pp, long tmo,
+ struct timespec *until)
+{
+ char path[PATH_MAX];
+ struct timespec now, ftimes[2], tdiff;
+ struct stat st;
+ long fd;
+ int r, err, retries = 0;
+
+ clock_gettime(CLOCK_REALTIME, &now);
+
+ if (snprintf(path, sizeof(path), "%s/%s", shm_find_mp_dir, pp->dev_t)
+ >= sizeof(path)) {
+ condlog(1, "%s: path name overflow", __func__);
+ return FIND_MULTIPATHS_ERROR;
+ }
+
+ if (ensure_directories_exist(path, 0700)) {
+ condlog(1, "%s: error creating directories", __func__);
+ return FIND_MULTIPATHS_ERROR;
+ }
+
+retry:
+ fd = open(path, O_RDONLY);
+ if (fd != -1) {
+ pthread_cleanup_push(close_fd, (void *)fd);
+ r = fstat(fd, &st);
+ if (r != 0)
+ err = errno;
+ pthread_cleanup_pop(1);
+
+ } else if (tmo > 0) {
+ if (errno == ENOENT)
+ fd = open(path, O_RDWR|O_EXCL|O_CREAT, 0644);
+ if (fd == -1) {
+ if (errno == EEXIST && !retries++)
+ /* We could have raced with another process */
+ goto retry;
+ condlog(1, "%s: error opening %s: %s",
+ __func__, path, strerror(errno));
+ return FIND_MULTIPATHS_ERROR;
+ };
+
+ pthread_cleanup_push(close_fd, (void *)fd);
+ /*
+ * We just created the file. Set st_mtim to our desired
+ * expiry time.
+ */
+ ftimes[0].tv_sec = 0;
+ ftimes[0].tv_nsec = UTIME_OMIT;
+ ftimes[1].tv_sec = now.tv_sec + tmo;
+ ftimes[1].tv_nsec = now.tv_nsec;
+ if (futimens(fd, ftimes) != 0) {
+ condlog(1, "%s: error in futimens(%s): %s", __func__,
+ path, strerror(errno));
+ }
+ r = fstat(fd, &st);
+ if (r != 0)
+ err = errno;
+ pthread_cleanup_pop(1);
+ } else
+ return FIND_MULTIPATHS_NEVER;
+
+ if (r != 0) {
+ condlog(1, "%s: error in fstat for %s: %s", __func__,
+ path, strerror(err));
+ return FIND_MULTIPATHS_ERROR;
+ }
+
+ timespecsub(&st.st_mtim, &now, &tdiff);
+
+ if (tdiff.tv_sec <= 0)
+ return FIND_MULTIPATHS_WAIT_DONE;
+
+ *until = tdiff;
+ return FIND_MULTIPATHS_WAITING;
+}
+
static int print_cmd_valid(int k, const vector pathvec,
struct config *conf)
{
static const int vals[] = { 1, 0, 2 };
+ int wait = FIND_MULTIPATHS_NEVER;
+ struct timespec until;
+ struct path *pp;
if (k < 0 || k >= sizeof(vals))
return 1;
+ if (k == 2) {
+ /*
+ * Caller ensures that pathvec[0] is the path to
+ * examine.
+ */
+ pp = VECTOR_SLOT(pathvec, 0);
+ select_find_multipaths_timeout(conf, pp);
+ wait = find_multipaths_check_timeout(
+ pp, pp->find_multipaths_timeout, &until);
+ if (wait != FIND_MULTIPATHS_WAITING)
+ k = 1;
+ } else if (pathvec != NULL) {
+ pp = VECTOR_SLOT(pathvec, 0);
+ wait = find_multipaths_check_timeout(pp, 0, &until);
+ }
+ if (wait == FIND_MULTIPATHS_WAITING)
+ printf("FIND_MULTIPATHS_WAIT_UNTIL=\"%ld.%06ld\"\n",
+ until.tv_sec, until.tv_nsec/1000);
+ else if (wait == FIND_MULTIPATHS_WAIT_DONE)
+ printf("FIND_MULTIPATHS_WAIT_UNTIL=\"0\"\n");
printf("DM_MULTIPATH_DEVICE_PATH=\"%d\"\n", vals[k]);
return k == 1;
}
diff --git a/multipath/multipath.rules b/multipath/multipath.rules
index aab64dc7..37f4f6d8 100644
--- a/multipath/multipath.rules
+++ b/multipath/multipath.rules
@@ -1,7 +1,9 @@
# Set DM_MULTIPATH_DEVICE_PATH if the device should be handled by multipath
SUBSYSTEM!="block", GOTO="end_mpath"
-ACTION!="add|change", GOTO="end_mpath"
KERNEL!="sd*|dasd*|nvme*", GOTO="end_mpath"
+ACTION=="remove", TEST=="/dev/shm/multipath/find_multipaths/$major:$minor", \
+ RUN+="/usr/bin/rm -f /dev/shm/multipath/find_multipaths/$major:$minor"
+ACTION!="add|change", GOTO="end_mpath"
IMPORT{cmdline}="nompath"
ENV{nompath}=="?*", GOTO="end_mpath"
--
2.16.1
--
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