From: David Howells <dhowells@redhat.com>
To: torvalds@linux-foundation.org
Cc: dhowells@redhat.com,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Casey Schaufler <casey@schaufler-ca.com>,
Stephen Smalley <sds@tycho.nsa.gov>,
nicolas.dichtel@6wind.com, raven@themaw.net,
Christian Brauner <christian@brauner.io>,
dhowells@redhat.com, keyrings@vger.kernel.org,
linux-usb@vger.kernel.org, linux-block@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [RFC PATCH 11/14] block: Add block layer notifications [ver #2]
Date: Thu, 07 Nov 2019 13:37:00 +0000 [thread overview]
Message-ID: <157313382004.29677.14535762370731716841.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <157313371694.29677.15388731274912671071.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:
pipe2(fds, O_NOTIFICATION_PIPE);
ioctl(fds[1], IOC_WATCH_QUEUE_SET_SIZE, 256);
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(fds[1], IOC_WATCH_QUEUE_SET_FILTER, &filter);
watch_devices(fds[1], 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 | 4 +++-
block/Kconfig | 9 +++++++++
block/blk-core.c | 29 ++++++++++++++++++++++++++++
include/linux/blkdev.h | 15 ++++++++++++++
include/uapi/linux/watch_queue.h | 30 ++++++++++++++++++++++++++++-
samples/watch_queue/watch_test.c | 40 +++++++++++++++++++++++++++++++++++++-
6 files changed, 124 insertions(+), 3 deletions(-)
diff --git a/Documentation/watch_queue.rst b/Documentation/watch_queue.rst
index ed592700be0e..f2299f631ae8 100644
--- a/Documentation/watch_queue.rst
+++ b/Documentation/watch_queue.rst
@@ -8,7 +8,9 @@ opened by userspace. This can be used in conjunction with::
* Key/keyring notifications
- * General device event notifications
+ * General device event notifications, including::
+
+ * Block layer event notifications
The notifications buffers can be enabled by:
diff --git a/block/Kconfig b/block/Kconfig
index 41c0917ce622..0906227a9431 100644
--- a/block/Kconfig
+++ b/block/Kconfig
@@ -177,6 +177,15 @@ 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"
+ depends on 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 d5e668ec751b..08e9b12ff5a5 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -184,6 +184,22 @@ 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;
@@ -224,6 +240,19 @@ static void print_req_error(struct request *req, blk_status_t status,
req->cmd_flags & ~REQ_OP_MASK,
req->nr_phys_segments,
IOPRIO_PRIO_CLASS(req->ioprio));
+
+#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 = watch_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 f3ea78b0c91c..477472c11815 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -27,6 +27,7 @@
#include <linux/percpu-refcount.h>
#include <linux/scatterlist.h>
#include <linux/blkzoned.h>
+#include <linux/watch_queue.h>
struct module;
struct scsi_ioctl_command;
@@ -1773,6 +1774,20 @@ 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 c3d8320b5d3a..557771413242 100644
--- a/include/uapi/linux/watch_queue.h
+++ b/include/uapi/linux/watch_queue.h
@@ -14,7 +14,8 @@
enum watch_notification_type {
WATCH_TYPE_META = 0, /* Special record */
WATCH_TYPE_KEY_NOTIFY = 1, /* Key change event notification */
- WATCH_TYPE__NR = 2
+ WATCH_TYPE_BLOCK_NOTIFY = 2, /* Block layer event notification */
+ WATCH_TYPE__NR = 3
};
enum watch_meta_notification_subtype {
@@ -101,4 +102,31 @@ struct key_notification {
__u32 aux; /* Per-type auxiliary data */
};
+/*
+ * 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 */
diff --git a/samples/watch_queue/watch_test.c b/samples/watch_queue/watch_test.c
index 58e826109ecc..55879531a7d5 100644
--- a/samples/watch_queue/watch_test.c
+++ b/samples/watch_queue/watch_test.c
@@ -58,6 +58,32 @@ static void saw_key_change(struct watch_notification *n, size_t len)
k->key_id, n->subtype, key_subtypes[n->subtype], k->aux);
}
+static const char *block_subtypes[256] = {
+ [NOTIFY_BLOCK_ERROR_TIMEOUT] = "timeout",
+ [NOTIFY_BLOCK_ERROR_NO_SPACE] = "critical space allocation",
+ [NOTIFY_BLOCK_ERROR_RECOVERABLE_TRANSPORT] = "recoverable transport",
+ [NOTIFY_BLOCK_ERROR_CRITICAL_TARGET] = "critical target",
+ [NOTIFY_BLOCK_ERROR_CRITICAL_NEXUS] = "critical nexus",
+ [NOTIFY_BLOCK_ERROR_CRITICAL_MEDIUM] = "critical medium",
+ [NOTIFY_BLOCK_ERROR_PROTECTION] = "protection",
+ [NOTIFY_BLOCK_ERROR_KERNEL_RESOURCE] = "kernel resource",
+ [NOTIFY_BLOCK_ERROR_DEVICE_RESOURCE] = "device resource",
+ [NOTIFY_BLOCK_ERROR_IO] = "I/O",
+};
+
+static void saw_block_change(struct watch_notification *n, size_t len)
+{
+ struct block_notification *b = (struct block_notification *)n;
+
+ if (len < sizeof(struct block_notification))
+ return;
+
+ printf("BLOCK %08llx e=%u[%s] s=%llx\n",
+ (unsigned long long)b->dev,
+ n->subtype, block_subtypes[n->subtype],
+ (unsigned long long)b->sector);
+}
+
/*
* Consume and display events.
*/
@@ -131,6 +157,9 @@ static void consumer(int fd)
case WATCH_TYPE_KEY_NOTIFY:
saw_key_change(&n.n, len);
break;
+ case WATCH_TYPE_BLOCK_NOTIFY:
+ saw_block_change(&n.n, len);
+ break;
default:
printf("other type\n");
break;
@@ -142,12 +171,16 @@ static void consumer(int fd)
}
static struct watch_notification_filter filter = {
- .nr_filters = 1,
+ .nr_filters = 2,
.filters = {
[0] = {
.type = WATCH_TYPE_KEY_NOTIFY,
.subtype_filter[0] = UINT_MAX,
},
+ [1] = {
+ .type = WATCH_TYPE_BLOCK_NOTIFY,
+ .subtype_filter[0] = UINT_MAX,
+ },
},
};
@@ -181,6 +214,11 @@ int main(int argc, char **argv)
exit(1);
}
+ if (syscall(__NR_watch_devices, fd, 0x04, 0) == -1) {
+ perror("watch_devices");
+ exit(1);
+ }
+
consumer(fd);
exit(0);
}
next prev parent reply other threads:[~2019-11-07 13:37 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-07 13:35 [RFC PATCH 00/14] pipe: Keyrings, Block and USB notifications [ver #2] David Howells
2019-11-07 13:35 ` [RFC PATCH 01/14] uapi: General notification queue definitions " David Howells
2019-11-07 13:35 ` [RFC PATCH 02/14] security: Add hooks to rule on setting a watch " David Howells
2019-11-07 13:35 ` [RFC PATCH 03/14] security: Add a hook for the point of notification insertion " David Howells
2019-11-07 13:35 ` [RFC PATCH 04/14] pipe: Add O_NOTIFICATION_PIPE " David Howells
2019-11-07 18:16 ` Andy Lutomirski
2019-11-07 18:48 ` David Howells
2019-11-08 5:06 ` Andy Lutomirski
2019-11-08 6:42 ` David Howells
2019-11-07 13:36 ` [RFC PATCH 05/14] pipe: Add general notification queue support " David Howells
2019-11-07 13:36 ` [RFC PATCH 06/14] keys: Add a notification facility " David Howells
2019-11-07 13:36 ` [RFC PATCH 07/14] Add sample notification program " David Howells
2019-11-07 13:36 ` [RFC PATCH 08/14] pipe: Allow buffers to be marked read-whole-or-error for notifications " David Howells
2019-11-07 18:15 ` Andy Lutomirski
2019-11-07 18:23 ` David Howells
2019-11-07 13:36 ` [RFC PATCH 09/14] pipe: Add notification lossage handling " David Howells
2019-11-07 13:36 ` [RFC PATCH 10/14] Add a general, global device notification watch list " David Howells
2019-11-07 13:37 ` David Howells [this message]
2019-11-07 13:37 ` [RFC PATCH 12/14] usb: Add USB subsystem notifications " David Howells
2019-11-07 13:37 ` [RFC PATCH 13/14] selinux: Implement the watch_key security hook " David Howells
2019-11-07 13:37 ` [RFC PATCH 14/14] smack: Implement the watch_key and post_notification hooks " David Howells
2019-11-07 17:16 ` [RFC PATCH 05/14] pipe: Add general notification queue support " David Howells
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