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Registered in England and Wales under Company Registration No. 3798903 Subject: [RFC PATCH 18/21] block: Add block layer notifications From: David Howells To: torvalds@linux-foundation.org Cc: dhowells@redhat.com, Casey Schaufler , Stephen Smalley , Greg Kroah-Hartman , nicolas.dichtel@6wind.com, raven@themaw.net, Christian Brauner , 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 Date: Tue, 15 Oct 2019 22:50:31 +0100 Message-ID: <157117623165.15019.7188193153962358526.stgit@warthog.procyon.org.uk> In-Reply-To: <157117606853.15019.15459271147790470307.stgit@warthog.procyon.org.uk> References: <157117606853.15019.15459271147790470307.stgit@warthog.procyon.org.uk> User-Agent: StGit/unknown-version MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.42]); Tue, 15 Oct 2019 21:50:35 +0000 (UTC) Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org 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_TMPFILE); 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 --- 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 #include #include +#include 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 14fee36ec000..65b127ca272b 100644 --- a/include/uapi/linux/watch_queue.h +++ b/include/uapi/linux/watch_queue.h @@ -11,7 +11,8 @@ 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 { @@ -98,4 +99,31 @@ 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 1ffed42bfece..263dbba59651 100644 --- a/samples/watch_queue/watch_test.c +++ b/samples/watch_queue/watch_test.c @@ -59,6 +59,32 @@ 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. */ @@ -132,6 +158,9 @@ 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; @@ -143,12 +172,16 @@ 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, + }, }, }; @@ -182,6 +215,11 @@ 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); }