From patchwork Thu Oct 29 14:58:41 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 311095 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BB49FC56201 for ; Thu, 29 Oct 2020 15:51:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3FA3121548 for ; Thu, 29 Oct 2020 15:51:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="a8ovsw3q" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728527AbgJ2PvB (ORCPT ); Thu, 29 Oct 2020 11:51:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49632 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728509AbgJ2Pu7 (ORCPT ); Thu, 29 Oct 2020 11:50:59 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5E3B3C0613CF; Thu, 29 Oct 2020 08:41:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=iBrwQ7u9qumc4njkhWiPx+LnMHepKgVCZBO024rsKVU=; b=a8ovsw3qEH9a1JE2dbyz8caYti XhDBkiE63ZuKYUZXZB77wo6BJuHEkndi44+JMWdHQsYop8n/jNE/wsrsTlb3x7e1p2A7qHSj6WUOv cmQSsRgTkw36FvlABOPWp+LZlsDHWmIcbxbmFFVEeGTeg7fhq+Z9WTPIYnaw7HW9GB6lHx45/sHXr HaiSW4mrH0pCqgEAfNRUvQXM8SvqJSvMRLJK4RaoZKpEbpcjHTAQnP0t9j9qDs3f6ecH12mk2TI7C 84wp+P+WARddkTA3COwlZ9AszfSNliRI2an3cxPSNvlgA6YQifX4GtjLiyBqniUfq5YnE8t5Kom7V zBOeCiYA==; Received: from 089144193201.atnat0002.highway.a1.net ([89.144.193.201] helo=localhost) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kYA3J-0008Dj-A7; Thu, 29 Oct 2020 15:41:26 +0000 From: Christoph Hellwig To: Jens Axboe Cc: Greg Kroah-Hartman , "Rafael J. Wysocki" , Denis Efremov , "David S. Miller" , Song Liu , Al Viro , Finn Thain , Michael Schmitz , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org, linux-raid@vger.kernel.org, linux-scsi@vger.kernel.org, linux-m68k@lists.linux-m68k.org, Hannes Reinecke Subject: [PATCH 18/18] block: switch gendisk lookup to a simple xarray Date: Thu, 29 Oct 2020 15:58:41 +0100 Message-Id: <20201029145841.144173-19-hch@lst.de> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201029145841.144173-1-hch@lst.de> References: <20201029145841.144173-1-hch@lst.de> MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org Now that bdev_map is only used for finding gendisks, we can use a simple xarray instead of the regions tracking structure for it. Signed-off-by: Christoph Hellwig Reviewed-by: Hannes Reinecke Reviewed-by: Greg Kroah-Hartman --- block/genhd.c | 208 ++++++++---------------------------------- include/linux/genhd.h | 7 -- 2 files changed, 37 insertions(+), 178 deletions(-) diff --git a/block/genhd.c b/block/genhd.c index e78c95cf3c00a9..439b444cac2038 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -27,15 +27,7 @@ static struct kobject *block_depr; -struct bdev_map { - struct bdev_map *next; - dev_t dev; - unsigned long range; - struct module *owner; - struct kobject *(*probe)(dev_t, int *, void *); - int (*lock)(dev_t, void *); - void *data; -} *bdev_map[255]; +static DEFINE_XARRAY(bdev_map); static DEFINE_MUTEX(bdev_map_lock); /* for extended dynamic devt allocation, currently only one major is used */ @@ -646,85 +638,26 @@ static char *bdevt_str(dev_t devt, char *buf) return buf; } -/* - * Register device numbers dev..(dev+range-1) - * range must be nonzero - * The hash chain is sorted on range, so that subranges can override. - */ -void blk_register_region(dev_t devt, unsigned long range, struct module *module, - struct kobject *(*probe)(dev_t, int *, void *), - int (*lock)(dev_t, void *), void *data) -{ - unsigned n = MAJOR(devt + range - 1) - MAJOR(devt) + 1; - unsigned index = MAJOR(devt); - unsigned i; - struct bdev_map *p; - - n = min(n, 255u); - p = kmalloc_array(n, sizeof(struct bdev_map), GFP_KERNEL); - if (p == NULL) - return; - - for (i = 0; i < n; i++, p++) { - p->owner = module; - p->probe = probe; - p->lock = lock; - p->dev = devt; - p->range = range; - p->data = data; - } +static void blk_register_region(struct gendisk *disk) +{ + int i; mutex_lock(&bdev_map_lock); - for (i = 0, p -= n; i < n; i++, p++, index++) { - struct bdev_map **s = &bdev_map[index % 255]; - while (*s && (*s)->range < range) - s = &(*s)->next; - p->next = *s; - *s = p; + for (i = 0; i < disk->minors; i++) { + if (xa_insert(&bdev_map, disk_devt(disk) + i, disk, GFP_KERNEL)) + WARN_ON_ONCE(1); } mutex_unlock(&bdev_map_lock); } -EXPORT_SYMBOL(blk_register_region); -void blk_unregister_region(dev_t devt, unsigned long range) +static void blk_unregister_region(struct gendisk *disk) { - unsigned n = MAJOR(devt + range - 1) - MAJOR(devt) + 1; - unsigned index = MAJOR(devt); - unsigned i; - struct bdev_map *found = NULL; + int i; mutex_lock(&bdev_map_lock); - for (i = 0; i < min(n, 255u); i++, index++) { - struct bdev_map **s; - for (s = &bdev_map[index % 255]; *s; s = &(*s)->next) { - struct bdev_map *p = *s; - if (p->dev == devt && p->range == range) { - *s = p->next; - if (!found) - found = p; - break; - } - } - } + for (i = 0; i < disk->minors; i++) + xa_erase(&bdev_map, disk_devt(disk) + i); mutex_unlock(&bdev_map_lock); - kfree(found); -} -EXPORT_SYMBOL(blk_unregister_region); - -static struct kobject *exact_match(dev_t devt, int *partno, void *data) -{ - struct gendisk *p = data; - - return &disk_to_dev(p)->kobj; -} - -static int exact_lock(dev_t devt, void *data) -{ - struct gendisk *p = data; - - if (!get_disk_and_module(p)) - return -1; - return 0; } static void disk_scan_partitions(struct gendisk *disk) @@ -870,8 +803,7 @@ static void __device_add_disk(struct device *parent, struct gendisk *disk, ret = bdi_register(bdi, "%u:%u", MAJOR(devt), MINOR(devt)); WARN_ON(ret); bdi_set_owner(bdi, dev); - blk_register_region(disk_devt(disk), disk->minors, NULL, - exact_match, exact_lock, disk); + blk_register_region(disk); } register_disk(parent, disk, groups); if (register_queue) @@ -984,7 +916,7 @@ void del_gendisk(struct gendisk *disk) blk_unregister_queue(disk); if (!(disk->flags & GENHD_FL_HIDDEN)) - blk_unregister_region(disk_devt(disk), disk->minors); + blk_unregister_region(disk); /* * Remove gendisk pointer from idr so that it cannot be looked up * while RCU period before freeing gendisk is running to prevent @@ -1050,54 +982,22 @@ static void request_gendisk_module(dev_t devt) request_module("block-major-%d", MAJOR(devt)); } -static struct gendisk *lookup_gendisk(dev_t dev, int *partno) +static bool get_disk_and_module(struct gendisk *disk) { - struct kobject *kobj; - struct bdev_map *p; - unsigned long best = ~0UL; - -retry: - mutex_lock(&bdev_map_lock); - for (p = bdev_map[MAJOR(dev) % 255]; p; p = p->next) { - struct kobject *(*probe)(dev_t, int *, void *); - struct module *owner; - void *data; - - if (p->dev > dev || p->dev + p->range - 1 < dev) - continue; - if (p->range - 1 >= best) - break; - if (!try_module_get(p->owner)) - continue; - owner = p->owner; - data = p->data; - probe = p->probe; - best = p->range - 1; - *partno = dev - p->dev; - - if (!probe) { - mutex_unlock(&bdev_map_lock); - module_put(owner); - request_gendisk_module(dev); - goto retry; - } + struct module *owner; - if (p->lock && p->lock(dev, data) < 0) { - module_put(owner); - continue; - } - mutex_unlock(&bdev_map_lock); - kobj = probe(dev, partno, data); - /* Currently ->owner protects _only_ ->probe() itself. */ + if (!disk->fops) + return false; + owner = disk->fops->owner; + if (owner && !try_module_get(owner)) + return false; + if (!kobject_get_unless_zero(&disk_to_dev(disk)->kobj)) { module_put(owner); - if (kobj) - return dev_to_disk(kobj_to_dev(kobj)); - goto retry; + return false; } - mutex_unlock(&bdev_map_lock); - return NULL; -} + return true; +} /** * get_gendisk - get partitioning information for a given device @@ -1116,7 +1016,19 @@ struct gendisk *get_gendisk(dev_t devt, int *partno) might_sleep(); if (MAJOR(devt) != BLOCK_EXT_MAJOR) { - disk = lookup_gendisk(devt, partno); + mutex_lock(&bdev_map_lock); + disk = xa_load(&bdev_map, devt); + if (!disk) { + mutex_unlock(&bdev_map_lock); + request_gendisk_module(devt); + mutex_lock(&bdev_map_lock); + disk = xa_load(&bdev_map, devt); + } + if (disk && !get_disk_and_module(disk)) + disk = NULL; + if (disk) + *partno = devt - disk_devt(disk); + mutex_unlock(&bdev_map_lock); } else { struct hd_struct *part; @@ -1320,21 +1232,6 @@ static const struct seq_operations partitions_op = { }; #endif -static void bdev_map_init(void) -{ - struct bdev_map *base; - int i; - - base = kzalloc(sizeof(*base), GFP_KERNEL); - if (!base) - panic("cannot allocate bdev_map"); - - base->dev = 1; - base->range = ~0 ; - for (i = 0; i < 255; i++) - bdev_map[i] = base; -} - static int __init genhd_device_init(void) { int error; @@ -1343,7 +1240,6 @@ static int __init genhd_device_init(void) error = class_register(&block_class); if (unlikely(error)) return error; - bdev_map_init(); blk_dev_init(); register_blkdev(BLOCK_EXT_MAJOR, "blkext"); @@ -1892,35 +1788,6 @@ struct gendisk *__alloc_disk_node(int minors, int node_id) } EXPORT_SYMBOL(__alloc_disk_node); -/** - * get_disk_and_module - increments the gendisk and gendisk fops module refcount - * @disk: the struct gendisk to increment the refcount for - * - * This increments the refcount for the struct gendisk, and the gendisk's - * fops module owner. - * - * Context: Any context. - */ -struct kobject *get_disk_and_module(struct gendisk *disk) -{ - struct module *owner; - struct kobject *kobj; - - if (!disk->fops) - return NULL; - owner = disk->fops->owner; - if (owner && !try_module_get(owner)) - return NULL; - kobj = kobject_get_unless_zero(&disk_to_dev(disk)->kobj); - if (kobj == NULL) { - module_put(owner); - return NULL; - } - return kobj; - -} -EXPORT_SYMBOL(get_disk_and_module); - /** * put_disk - decrements the gendisk refcount * @disk: the struct gendisk to decrement the refcount for @@ -1957,7 +1824,6 @@ void put_disk_and_module(struct gendisk *disk) module_put(owner); } } -EXPORT_SYMBOL(put_disk_and_module); static void set_disk_ro_uevent(struct gendisk *gd, int ro) { diff --git a/include/linux/genhd.h b/include/linux/genhd.h index 14b1bc7dea21d8..77c3489991f42e 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -340,15 +340,8 @@ int blk_add_partitions(struct gendisk *disk, struct block_device *bdev); int blk_drop_partitions(struct block_device *bdev); extern struct gendisk *__alloc_disk_node(int minors, int node_id); -extern struct kobject *get_disk_and_module(struct gendisk *disk); extern void put_disk(struct gendisk *disk); extern void put_disk_and_module(struct gendisk *disk); -extern void blk_register_region(dev_t devt, unsigned long range, - struct module *module, - struct kobject *(*probe)(dev_t, int *, void *), - int (*lock)(dev_t, void *), - void *data); -extern void blk_unregister_region(dev_t devt, unsigned long range); #define alloc_disk_node(minors, node_id) \ ({ \