From: David Howells <dhowells@redhat.com>
To: viro@zeniv.linux.org.uk
Cc: dhowells@redhat.com, raven@themaw.net,
linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org,
linux-block@vger.kernel.org, keyrings@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [PATCH 11/13] block: Add block layer notifications [ver #4]
Date: Fri, 07 Jun 2019 15:19:04 +0100 [thread overview]
Message-ID: <155991714448.15579.1960242962075486353.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <155991702981.15579.6007568669839441045.stgit@warthog.procyon.org.uk>
Add a block layer notification mechanism whereby notifications about
block-layer events such as I/O errors, can be reported to a monitoring
process asynchronously.
Firstly, an event queue needs to be created:
fd = open("/dev/event_queue", O_RDWR);
ioctl(fd, IOC_WATCH_QUEUE_SET_SIZE, page_size << n);
then a notification can be set up to report block notifications via that
queue:
struct watch_notification_filter filter = {
.nr_filters = 1,
.filters = {
[0] = {
.type = WATCH_TYPE_BLOCK_NOTIFY,
.subtype_filter[0] = UINT_MAX;
},
},
};
ioctl(fd, IOC_WATCH_QUEUE_SET_FILTER, &filter);
watch_devices(fd, 12);
After that, records will be placed into the queue when, for example, errors
occur on a block device. Records are of the following format:
struct block_notification {
struct watch_notification watch;
__u64 dev;
__u64 sector;
} *n;
Where:
n->watch.type will be WATCH_TYPE_BLOCK_NOTIFY
n->watch.subtype will be the type of notification, such as
NOTIFY_BLOCK_ERROR_CRITICAL_MEDIUM.
n->watch.info & WATCH_INFO_LENGTH will indicate the length of the
record.
n->watch.info & WATCH_INFO_ID will be the second argument to
watch_devices(), shifted.
n->dev will be the device numbers munged together.
n->sector will indicate the affected sector (if appropriate for the
event).
Note that it is permissible for event records to be of variable length -
or, at least, the length may be dependent on the subtype.
Signed-off-by: David Howells <dhowells@redhat.com>
---
Documentation/watch_queue.rst | 10 +++++++++-
block/Kconfig | 9 +++++++++
block/blk-core.c | 29 +++++++++++++++++++++++++++++
include/linux/blkdev.h | 15 +++++++++++++++
include/uapi/linux/watch_queue.h | 27 +++++++++++++++++++++++++++
5 files changed, 89 insertions(+), 1 deletion(-)
diff --git a/Documentation/watch_queue.rst b/Documentation/watch_queue.rst
index e4b8233d5aa8..c2954e191989 100644
--- a/Documentation/watch_queue.rst
+++ b/Documentation/watch_queue.rst
@@ -11,7 +11,9 @@ receive notifications from the kernel. This can be used in conjunction with::
* Superblock event notifications
- * General device event notifications
+ * General device event notifications, including::
+
+ * Block layer event notifications
The notifications buffers can be enabled by:
@@ -336,6 +338,12 @@ Any particular buffer can be fed from multiple sources. Sources include:
See Documentation/security/keys/core.rst for more information.
+ * WATCH_TYPE_BLOCK_NOTIFY
+
+ Notifications of this type indicate block layer events, such as I/O errors
+ or temporary link loss. Watchpoints of this type are set on the global
+ device watch list.
+
Event Filtering
===============
diff --git a/block/Kconfig b/block/Kconfig
index 1b220101a9cb..4ff4a56ba9f9 100644
--- a/block/Kconfig
+++ b/block/Kconfig
@@ -163,6 +163,15 @@ config BLK_SED_OPAL
Enabling this option enables users to setup/unlock/lock
Locking ranges for SED devices using the Opal protocol.
+config BLK_NOTIFICATIONS
+ bool "Block layer event notifications"
+ select DEVICE_NOTIFICATIONS
+ help
+ This option provides support for getting block layer event
+ notifications. This makes use of the /dev/watch_queue misc device to
+ handle the notification buffer and provides the device_notify() system
+ call to enable/disable watches.
+
menu "Partition Types"
source "block/partitions/Kconfig"
diff --git a/block/blk-core.c b/block/blk-core.c
index 419d600e6637..edad86172d47 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -144,6 +144,22 @@ static const struct {
[BLK_STS_IOERR] = { -EIO, "I/O" },
};
+#ifdef CONFIG_BLK_NOTIFICATIONS
+static const
+enum block_notification_type blk_notifications[ARRAY_SIZE(blk_errors)] = {
+ [BLK_STS_TIMEOUT] = NOTIFY_BLOCK_ERROR_TIMEOUT,
+ [BLK_STS_NOSPC] = NOTIFY_BLOCK_ERROR_NO_SPACE,
+ [BLK_STS_TRANSPORT] = NOTIFY_BLOCK_ERROR_RECOVERABLE_TRANSPORT,
+ [BLK_STS_TARGET] = NOTIFY_BLOCK_ERROR_CRITICAL_TARGET,
+ [BLK_STS_NEXUS] = NOTIFY_BLOCK_ERROR_CRITICAL_NEXUS,
+ [BLK_STS_MEDIUM] = NOTIFY_BLOCK_ERROR_CRITICAL_MEDIUM,
+ [BLK_STS_PROTECTION] = NOTIFY_BLOCK_ERROR_PROTECTION,
+ [BLK_STS_RESOURCE] = NOTIFY_BLOCK_ERROR_KERNEL_RESOURCE,
+ [BLK_STS_DEV_RESOURCE] = NOTIFY_BLOCK_ERROR_DEVICE_RESOURCE,
+ [BLK_STS_IOERR] = NOTIFY_BLOCK_ERROR_IO,
+};
+#endif
+
blk_status_t errno_to_blk_status(int errno)
{
int i;
@@ -179,6 +195,19 @@ static void print_req_error(struct request *req, blk_status_t status)
req->rq_disk ? req->rq_disk->disk_name : "?",
(unsigned long long)blk_rq_pos(req),
req->cmd_flags);
+
+#ifdef CONFIG_BLK_NOTIFICATIONS
+ if (blk_notifications[idx]) {
+ struct block_notification n = {
+ .watch.type = WATCH_TYPE_BLOCK_NOTIFY,
+ .watch.subtype = blk_notifications[idx],
+ .watch.info = sizeof(n),
+ .dev = req->rq_disk ? disk_devt(req->rq_disk) : 0,
+ .sector = blk_rq_pos(req),
+ };
+ post_block_notification(&n);
+ }
+#endif
}
static void req_bio_endio(struct request *rq, struct bio *bio,
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 1aafeb923e7b..8b8e235f47c9 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -43,6 +43,7 @@ struct pr_ops;
struct rq_qos;
struct blk_queue_stats;
struct blk_stat_callback;
+struct block_notification;
#define BLKDEV_MIN_RQ 4
#define BLKDEV_MAX_RQ 128 /* Default maximum */
@@ -1744,6 +1745,20 @@ static inline bool blk_req_can_dispatch_to_zone(struct request *rq)
}
#endif /* CONFIG_BLK_DEV_ZONED */
+#ifdef CONFIG_BLK_NOTIFICATIONS
+static inline void post_block_notification(struct block_notification *n)
+{
+ u64 id = 0; /* Might want to allow dev# here. */
+
+ post_device_notification(&n->watch, id);
+}
+#else
+static inline void post_block_notification(struct block_notification *n)
+{
+}
+#endif
+
+
#else /* CONFIG_BLOCK */
struct block_device;
diff --git a/include/uapi/linux/watch_queue.h b/include/uapi/linux/watch_queue.h
index aeffcfd7a742..22e3326b83a6 100644
--- a/include/uapi/linux/watch_queue.h
+++ b/include/uapi/linux/watch_queue.h
@@ -155,4 +155,31 @@ struct superblock_error_notification {
__u32 error_cookie;
};
+/*
+ * Type of block layer notification.
+ */
+enum block_notification_type {
+ NOTIFY_BLOCK_ERROR_TIMEOUT = 1, /* Timeout error */
+ NOTIFY_BLOCK_ERROR_NO_SPACE = 2, /* Critical space allocation error */
+ NOTIFY_BLOCK_ERROR_RECOVERABLE_TRANSPORT = 3, /* Recoverable transport error */
+ NOTIFY_BLOCK_ERROR_CRITICAL_TARGET = 4, /* Critical target error */
+ NOTIFY_BLOCK_ERROR_CRITICAL_NEXUS = 5, /* Critical nexus error */
+ NOTIFY_BLOCK_ERROR_CRITICAL_MEDIUM = 6, /* Critical medium error */
+ NOTIFY_BLOCK_ERROR_PROTECTION = 7, /* Protection error */
+ NOTIFY_BLOCK_ERROR_KERNEL_RESOURCE = 8, /* Kernel resource error */
+ NOTIFY_BLOCK_ERROR_DEVICE_RESOURCE = 9, /* Device resource error */
+ NOTIFY_BLOCK_ERROR_IO = 10, /* Other I/O error */
+};
+
+/*
+ * Block layer notification record.
+ * - watch.type = WATCH_TYPE_BLOCK_NOTIFY
+ * - watch.subtype = enum block_notification_type
+ */
+struct block_notification {
+ struct watch_notification watch; /* WATCH_TYPE_BLOCK_NOTIFY */
+ __u64 dev; /* Device number */
+ __u64 sector; /* Affected sector */
+};
+
#endif /* _UAPI_LINUX_WATCH_QUEUE_H */
next prev parent reply other threads:[~2019-06-07 14:19 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-07 14:17 [RFC][PATCH 00/13] Mount, FS, Block and Keyrings notifications [ver #4] David Howells
2019-06-07 14:17 ` [PATCH 01/13] security: Override creds in __fput() with last fputter's creds " David Howells
2019-06-07 14:17 ` [PATCH 02/13] uapi: General notification ring definitions " David Howells
2019-06-07 15:12 ` Darrick J. Wong
2019-06-07 15:30 ` David Howells
2019-06-07 15:51 ` David Howells
2019-06-09 4:35 ` Randy Dunlap
2019-06-13 13:34 ` David Howells
2019-06-13 14:49 ` Randy Dunlap
2019-06-07 14:17 ` [PATCH 03/13] security: Add hooks to rule on setting a watch " David Howells
2019-06-07 14:17 ` [PATCH 04/13] security: Add a hook for the point of notification insertion " David Howells
2019-06-07 14:18 ` [PATCH 05/13] General notification queue with user mmap()'able ring buffer " David Howells
2019-06-07 14:18 ` [PATCH 06/13] keys: Add a notification facility " David Howells
2019-06-10 17:11 ` Jonathan Corbet
2019-06-10 17:47 ` David Howells
2019-06-07 14:18 ` [PATCH 07/13] vfs: Add a mount-notification " David Howells
2019-06-07 14:18 ` [PATCH 08/13] vfs: Add superblock notifications " David Howells
2019-06-07 14:18 ` [PATCH 09/13] fsinfo: Export superblock notification counter " David Howells
2019-06-07 14:18 ` [PATCH 10/13] Add a general, global device notification watch list " David Howells
2019-06-07 14:19 ` David Howells [this message]
2019-06-07 14:19 ` [PATCH 12/13] usb: Add USB subsystem notifications " David Howells
2019-06-07 14:19 ` [PATCH 13/13] Add sample notification program " David Howells
2019-06-10 15:21 ` [RFC][PATCH 00/13] Mount, FS, Block and Keyrings notifications " Stephen Smalley
2019-06-10 16:33 ` Casey Schaufler
2019-06-10 16:42 ` Andy Lutomirski
2019-06-10 18:01 ` Casey Schaufler
2019-06-10 18:22 ` Andy Lutomirski
2019-06-10 19:33 ` Casey Schaufler
2019-06-10 19:53 ` Andy Lutomirski
2019-06-10 21:25 ` Casey Schaufler
2019-06-11 0:13 ` Andy Lutomirski
2019-06-11 14:32 ` Stephen Smalley
2019-06-12 8:55 ` David Howells
2019-06-10 22:07 ` David Howells
2019-06-11 14:21 ` What do LSMs *actually* need for checks on notifications? David Howells
2019-06-11 15:57 ` Stephen Smalley
2019-06-11 16:22 ` Casey Schaufler
2019-06-12 11:43 ` David Howells
2019-06-13 18:46 ` Stephen Smalley
2019-06-12 17:41 ` David Howells
2019-06-12 18:14 ` Casey Schaufler
2019-06-12 18:36 ` David Howells
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