From: Martin Wilck <mwilck@xxxxxxx>
The function dm_suspend_and_flush() introduced in 9a4ff93
tries to remove child maps (partitions) after suspending
the mpath device. This may lock up if removing the partitions
requires I/O. It's better to use the following sequence
of actions: 1) clear queue_if_no_path; 2) remove partitions;
3) suspend; 4) remove (or resume and restore queue_if_no_path
in case of failure).
This patch modifies the implementation by moving the
queue_if_no_path/suspend logic into _dm_flush_map().
A call to _dm_flush_map() with need_suspend=1 replaces
the previous call to dm_suspend_and_flush().
With this change, the mpath device is only suspended after
removing partmaps, avoiding the deadlock.
Fixes: 9a4ff93 "Switch off 'queue_if_no_path' before removing maps"
Signed-off-by: Martin Wilck <mwilck@xxxxxxxx>
---
libmultipath/devmapper.c | 102 ++++++++++++++++++++---------------------------
libmultipath/devmapper.h | 9 +++--
2 files changed, 49 insertions(+), 62 deletions(-)
diff --git a/libmultipath/devmapper.c b/libmultipath/devmapper.c
index 1576dd01..044be2be 100644
--- a/libmultipath/devmapper.c
+++ b/libmultipath/devmapper.c
@@ -760,12 +760,6 @@ out:
}
static int
-has_partmap(const char *name, void *data)
-{
- return 1;
-}
-
-static int
partmap_in_use(const char *name, void *data)
{
int part_count, *ret_count = (int *)data;
@@ -785,9 +779,13 @@ partmap_in_use(const char *name, void *data)
return 0;
}
-int _dm_flush_map(const char *mapname, int need_sync, int deferred_remove)
+int _dm_flush_map (const char * mapname, int need_sync, int deferred_remove,
+ int need_suspend, int retries)
{
int r;
+ int queue_if_no_path = 0;
+ unsigned long long mapsize;
+ char params[PARAMS_SIZE] = {0};
if (!dm_is_mpath(mapname))
return 0; /* nothing to do */
@@ -797,6 +795,16 @@ int _dm_flush_map(const char *mapname, int need_sync, int deferred_remove)
if (!do_deferred(deferred_remove) && partmap_in_use(mapname, NULL))
return 1;
+ if (need_suspend &&
+ !dm_get_map(mapname, &mapsize, params) &&
+ strstr(params, "queue_if_no_path")) {
+ if (!dm_queue_if_no_path((char *)mapname, 0))
+ queue_if_no_path = 1;
+ else
+ /* Leave queue_if_no_path alone if unset failed */
+ queue_if_no_path = -1;
+ }
+
if (dm_remove_partmaps(mapname, need_sync, deferred_remove))
return 1;
@@ -805,17 +813,36 @@ int _dm_flush_map(const char *mapname, int need_sync, int deferred_remove)
return 1;
}
- r = dm_device_remove(mapname, need_sync, deferred_remove);
+ do {
+ if (need_suspend && queue_if_no_path != -1)
+ dm_simplecmd_flush(DM_DEVICE_SUSPEND, mapname, 0);
- if (r) {
- if (do_deferred(deferred_remove) && dm_map_present(mapname)) {
- condlog(4, "multipath map %s remove deferred",
+ r = dm_device_remove(mapname, need_sync, deferred_remove);
+
+ if (r) {
+ if (do_deferred(deferred_remove)
+ && dm_map_present(mapname)) {
+ condlog(4, "multipath map %s remove deferred",
+ mapname);
+ return 2;
+ }
+ condlog(4, "multipath map %s removed", mapname);
+ return 0;
+ } else {
+ condlog(2, "failed to remove multipath map %s",
mapname);
- return 2;
+ if (need_suspend && queue_if_no_path != -1) {
+ dm_simplecmd_noflush(DM_DEVICE_RESUME,
+ mapname, 0);
+ }
}
- condlog(4, "multipath map %s removed", mapname);
- return 0;
- }
+ if (retries)
+ sleep(1);
+ } while (retries-- > 0);
+
+ if (queue_if_no_path == 1)
+ dm_queue_if_no_path((char *)mapname, 1);
+
return 1;
}
@@ -824,7 +851,7 @@ int _dm_flush_map(const char *mapname, int need_sync, int deferred_remove)
int
dm_flush_map_nopaths(const char * mapname, int deferred_remove)
{
- return _dm_flush_map(mapname, 1, deferred_remove);
+ return _dm_flush_map(mapname, 1, deferred_remove, 0, 0);
}
#else
@@ -832,52 +859,11 @@ dm_flush_map_nopaths(const char * mapname, int deferred_remove)
int
dm_flush_map_nopaths(const char * mapname, int deferred_remove)
{
- return _dm_flush_map(mapname, 1, 0);
+ return _dm_flush_map(mapname, 1, 0, 0, 0);
}
#endif
-int dm_suspend_and_flush_map (const char * mapname, int retries)
-{
- int need_reset = 0, queue_if_no_path = 0;
- unsigned long long mapsize;
- char params[PARAMS_SIZE] = {0};
- int udev_flags = 0;
-
- if (!dm_is_mpath(mapname))
- return 0; /* nothing to do */
-
- /* if the device currently has no partitions, do not
- run kpartx on it if you fail to delete it */
- if (do_foreach_partmaps(mapname, has_partmap, NULL) == 0)
- udev_flags |= MPATH_UDEV_NO_KPARTX_FLAG;
-
- if (!dm_get_map(mapname, &mapsize, params)) {
- if (strstr(params, "queue_if_no_path"))
- queue_if_no_path = 1;
- }
-
- if (queue_if_no_path && dm_queue_if_no_path((char *)mapname, 0) == 0)
- need_reset = 1;
-
- do {
- if (!queue_if_no_path || need_reset)
- dm_simplecmd_flush(DM_DEVICE_SUSPEND, mapname, 0);
-
- if (!dm_flush_map(mapname)) {
- condlog(4, "multipath map %s removed", mapname);
- return 0;
- }
- dm_simplecmd_noflush(DM_DEVICE_RESUME, mapname, udev_flags);
- if (retries)
- sleep(1);
- } while (retries-- > 0);
- condlog(2, "failed to remove multipath map %s", mapname);
- if (need_reset)
- dm_queue_if_no_path((char *)mapname, 1);
- return 1;
-}
-
int dm_flush_maps (int retries)
{
int r = 0;
diff --git a/libmultipath/devmapper.h b/libmultipath/devmapper.h
index 3ea43297..aca4454b 100644
--- a/libmultipath/devmapper.h
+++ b/libmultipath/devmapper.h
@@ -36,12 +36,13 @@ int dm_get_map(const char *, unsigned long long *, char *);
int dm_get_status(char *, char *);
int dm_type(const char *, char *);
int dm_is_mpath(const char *);
-int _dm_flush_map (const char *, int, int);
+int _dm_flush_map (const char *, int, int, int, int);
int dm_flush_map_nopaths(const char * mapname, int deferred_remove);
-#define dm_flush_map(mapname) _dm_flush_map(mapname, 1, 0)
-#define dm_flush_map_nosync(mapname) _dm_flush_map(mapname, 0, 0)
+#define dm_flush_map(mapname) _dm_flush_map(mapname, 1, 0, 0, 0)
+#define dm_flush_map_nosync(mapname) _dm_flush_map(mapname, 0, 0, 0, 0)
+#define dm_suspend_and_flush_map(mapname, retries) \
+ _dm_flush_map(mapname, 1, 0, 1, retries)
int dm_cancel_deferred_remove(struct multipath *mpp);
-int dm_suspend_and_flush_map(const char * mapname, int retries);
int dm_flush_maps (int retries);
int dm_fail_path(char * mapname, char * path);
int dm_reinstate_path(char * mapname, char * path);
--
2.11.0
--
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