From: Andy Grover <agrover@redhat.com>
To: gregkh@linuxfoundation.org, snitzer@redhat.com
Cc: dm-devel@redhat.com, linux-kernel@vger.kernel.org
Subject: [PATCH 4/9] dm: Update dm-uevent.txt
Date: Mon, 3 Oct 2016 12:22:55 -0700 [thread overview]
Message-ID: <1475522580-16723-5-git-send-email-agrover@redhat.com> (raw)
In-Reply-To: <1475522580-16723-1-git-send-email-agrover@redhat.com>
Document the current dm uevent API, as modified by this patchset.
Signed-off-by: Andy Grover <agrover@redhat.com>
---
Documentation/device-mapper/dm-uevent.txt | 49 ++++++++++++++++++++++++++-----
1 file changed, 42 insertions(+), 7 deletions(-)
diff --git a/Documentation/device-mapper/dm-uevent.txt b/Documentation/device-mapper/dm-uevent.txt
index 07edbd85..0a5d909 100644
--- a/Documentation/device-mapper/dm-uevent.txt
+++ b/Documentation/device-mapper/dm-uevent.txt
@@ -1,18 +1,53 @@
The device-mapper uevent code adds the capability to device-mapper to create
and send kobject uevents (uevents). Previously device-mapper events were only
-available through the ioctl interface. The advantage of the uevents interface
-is the event contains environment attributes providing increased context for
+available through the ioctl interface. The advantages of the uevents interface
+are the event contains environment attributes providing increased context for
the event avoiding the need to query the state of the device-mapper device after
-the event is received.
+the event is received, and uevents are poll()-able in userspace, whereas the
+ioctl event interface is not.
-There are two functions currently for device-mapper events. The first function
-listed creates the event and the second function sends the event(s).
+There are five functions DM targets should use.
-void dm_path_uevent(enum dm_uevent_type event_type, struct dm_target *ti,
- const char *path, unsigned nr_valid_paths)
+struct dm_uevent *dm_build_uevent(struct mapped_device *md,
+ struct dm_target *ti,
+ enum kobject_action action,
+ const char *dm_action)
+
+Construct a dm uevent with default DM variables attached(DM_TARGET,
+DM_ACTION, DM_SEQNUM).
+
+int add_uevent_var(struct kobj_uevent_env *env, const char *format, ...)
+
+Optionally add event-specific data to the generated uevent. e.g. dm-mpath's
+PATH_FAILED and PATH_REINSTATED uevents add path and number-of-remaining-paths
+vars.
+
+void dm_uevent_add(struct mapped_device *md, struct list_head *elist)
+
+Hand off the uevent to the device's list of pending events.
+
+void dm_uevent_free(struct dm_uevent *event)
+
+Something went wrong, free the uevent instead of queueing it.
+
+void dm_table_event(struct dm_table *t)
+
+Triggers sending of queued uevents as well as waking up processes waiting on
+the ioctl.
+
+
+The device-mapper uevent code also supplies three functions for device-mapper core
+to call:
+
+int dm_uevent_init(void)
+void dm_uevent_exit(void)
+
+Setup and teardown.
void dm_send_uevents(struct list_head *events, struct kobject *kobj)
+Actually send the uevents (called indirectly from dm_table_event, above).
+
The variables added to the uevent environment are:
--
2.7.4
next prev parent reply other threads:[~2016-10-03 19:24 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-03 19:22 [PATCH 0/9] Generate uevents for all DM events Andy Grover
2016-10-03 19:22 ` [PATCH 1/9] dm: Do not export dm_send_uevents Andy Grover
2016-10-03 19:22 ` [PATCH 2/9] dm: Move multipath-specific stuff out of dm-uevent.c Andy Grover
2016-10-03 19:22 ` [PATCH 3/9] dm: Inline dm_build_path_uevent into dm_path_uevent Andy Grover
2016-10-03 19:22 ` Andy Grover [this message]
2016-10-03 19:22 ` [PATCH 5/9] dm: Rename dm_build_uevent to dm_uevent_build Andy Grover
2016-10-03 19:22 ` [PATCH 6/9] dm: Rename dm_event_add to dm_event_queue Andy Grover
2016-10-03 19:22 ` [PATCH 7/9] dm: Implement dm_uevent_add() Andy Grover
2016-10-03 19:22 ` [PATCH 8/9] dm: Generate uevents for thin targets Andy Grover
2016-10-03 19:23 ` [PATCH 9/9] dm: Generate uevents for other targets Andy Grover
2016-10-03 19:29 ` [PATCH 0/9] Generate uevents for all DM events Mike Snitzer
2016-10-04 7:20 ` Greg KH
2016-10-04 23:39 ` Andy Grover
2016-10-05 0:40 ` [dm-devel] " Alasdair G Kergon
2016-10-05 6:26 ` Hannes Reinecke
2016-10-05 6:51 ` Greg KH
2016-10-05 17:06 ` Andy Grover
2016-10-05 17:43 ` Alasdair G Kergon
2016-10-05 22:30 ` Andy Grover
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