From patchwork Tue Nov 24 13:27:31 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 11928877 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=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 65765C825A6 for ; Tue, 24 Nov 2020 13:29:56 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A7E46206F9 for ; Tue, 24 Nov 2020 13:29:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="UXcIHkrY" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A7E46206F9 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 46B926B00F2; Tue, 24 Nov 2020 08:29:03 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 3D0336B00F3; Tue, 24 Nov 2020 08:29:03 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1A85C6B00F4; Tue, 24 Nov 2020 08:29:03 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id EDD896B00F2 for ; Tue, 24 Nov 2020 08:29:02 -0500 (EST) Received: from smtpin13.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id A86E68249980 for ; Tue, 24 Nov 2020 13:29:02 +0000 (UTC) X-FDA: 77519392524.13.brick18_100e5ec2736e Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin13.hostedemail.com (Postfix) with ESMTP id 84BB118140B67 for ; Tue, 24 Nov 2020 13:29:02 +0000 (UTC) X-HE-Tag: brick18_100e5ec2736e X-Filterd-Recvd-Size: 26522 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf05.hostedemail.com (Postfix) with ESMTP for ; Tue, 24 Nov 2020 13:29:01 +0000 (UTC) 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=GvPG4PqG1HoxFrUZUmZkM34iIp/y9TiIMmmO3FfXfkQ=; b=UXcIHkrYnPGd2/QIRLGaBVYf+e 0/rinjHWk+4qyNnPlWoC+vFKIiW+/w6eB6MPgLuRGHNzV/BlmKeWxR+fCkabLtgqmpqYLODQK2F4Y TNV7mRCk3eJkdhmhZPCMzdUwCutX6B9EFglaPZKsDWQFl7fSXBGZ9I3UcrwZKlFw7dpgRk0QLwtv5 MLnK//Qp55CbYNt+8EoXLU2Wm7uEH00ZYcOt9IXRofTnyRwQqly5MNRhYk7ruixE7JnGPXGi9thJO iHg6QY9r0szSId9BsqxORTDdqPs2FyUZ2xp2EAQjOmXy7towjAfqy+tmntGnikW8C482GmuaeKWWU 5ZTmEVnw==; Received: from [2001:4bb8:180:5443:c70:4a89:bc61:3] (helo=localhost) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1khYMz-0006bW-Ik; Tue, 24 Nov 2020 13:28:35 +0000 From: Christoph Hellwig To: Jens Axboe Cc: Tejun Heo , Josef Bacik , Konrad Rzeszutek Wilk , Coly Li , Mike Snitzer , Greg Kroah-Hartman , Jan Kara , Johannes Thumshirn , dm-devel@redhat.com, Richard Weinberger , Jan Kara , linux-block@vger.kernel.org, xen-devel@lists.xenproject.org, linux-bcache@vger.kernel.org, linux-mtd@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 25/45] block: reference struct block_device from struct hd_struct Date: Tue, 24 Nov 2020 14:27:31 +0100 Message-Id: <20201124132751.3747337-26-hch@lst.de> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201124132751.3747337-1-hch@lst.de> References: <20201124132751.3747337-1-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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: To simplify block device lookup and a few other upcoming areas, make sure that we always have a struct block_device available for each disk and each partition. The only downside of this is that each device and partition uses a little more memory. The upside will be that a lot of code can be simplified. With that all we need to look up the block device is to lookup the inode and do a few sanity checks on the gendisk, instead of the separate lookup for the gendisk. These checks are in a new RCU critical section and the disk is now freed using kfree_rcu(). As part of the change switch bdget() to only find existing block devices, given that we know that the block_device structure must be allocated at probe / partition scan time. Signed-off-by: Christoph Hellwig --- block/blk.h | 2 +- block/genhd.c | 212 ++++------------------------------------ block/partitions/core.c | 29 +++--- fs/block_dev.c | 171 ++++++++++++++++++-------------- include/linux/blkdev.h | 2 + include/linux/genhd.h | 6 +- 6 files changed, 140 insertions(+), 282 deletions(-) diff --git a/block/blk.h b/block/blk.h index dfab98465db9a5..c4839abcfa27eb 100644 --- a/block/blk.h +++ b/block/blk.h @@ -352,7 +352,6 @@ struct hd_struct *disk_map_sector_rcu(struct gendisk *disk, sector_t sector); int blk_alloc_devt(struct hd_struct *part, dev_t *devt); void blk_free_devt(dev_t devt); -void blk_invalidate_devt(dev_t devt); char *disk_name(struct gendisk *hd, int partno, char *buf); #define ADDPART_FLAG_NONE 0 #define ADDPART_FLAG_RAID 1 @@ -384,6 +383,7 @@ static inline void hd_free_part(struct hd_struct *part) { free_percpu(part->dkstats); kfree(part->info); + bdput(part->bdev); percpu_ref_exit(&part->ref); } diff --git a/block/genhd.c b/block/genhd.c index f46e89226fdf91..16c6b13242105b 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -27,17 +27,9 @@ static struct kobject *block_depr; -static DEFINE_XARRAY(bdev_map); -static DEFINE_MUTEX(bdev_map_lock); - /* for extended dynamic devt allocation, currently only one major is used */ #define NR_EXT_DEVT (1 << MINORBITS) - -/* For extended devt allocation. ext_devt_lock prevents look up - * results from going away underneath its user. - */ -static DEFINE_SPINLOCK(ext_devt_lock); -static DEFINE_IDR(ext_devt_idr); +static DEFINE_IDA(ext_devt_ida); static void disk_check_events(struct disk_events *ev, unsigned int *clearing_ptr); @@ -580,14 +572,7 @@ int blk_alloc_devt(struct hd_struct *part, dev_t *devt) return 0; } - /* allocate ext devt */ - idr_preload(GFP_KERNEL); - - spin_lock_bh(&ext_devt_lock); - idx = idr_alloc(&ext_devt_idr, part, 0, NR_EXT_DEVT, GFP_NOWAIT); - spin_unlock_bh(&ext_devt_lock); - - idr_preload_end(); + idx = ida_alloc_range(&ext_devt_ida, 0, NR_EXT_DEVT, GFP_KERNEL); if (idx < 0) return idx == -ENOSPC ? -EBUSY : idx; @@ -606,26 +591,8 @@ int blk_alloc_devt(struct hd_struct *part, dev_t *devt) */ void blk_free_devt(dev_t devt) { - if (devt == MKDEV(0, 0)) - return; - - if (MAJOR(devt) == BLOCK_EXT_MAJOR) { - spin_lock_bh(&ext_devt_lock); - idr_remove(&ext_devt_idr, blk_mangle_minor(MINOR(devt))); - spin_unlock_bh(&ext_devt_lock); - } -} - -/* - * We invalidate devt by assigning NULL pointer for devt in idr. - */ -void blk_invalidate_devt(dev_t devt) -{ - if (MAJOR(devt) == BLOCK_EXT_MAJOR) { - spin_lock_bh(&ext_devt_lock); - idr_replace(&ext_devt_idr, NULL, blk_mangle_minor(MINOR(devt))); - spin_unlock_bh(&ext_devt_lock); - } + if (MAJOR(devt) == BLOCK_EXT_MAJOR) + ida_free(&ext_devt_ida, blk_mangle_minor(MINOR(devt))); } static char *bdevt_str(dev_t devt, char *buf) @@ -640,28 +607,6 @@ static char *bdevt_str(dev_t devt, char *buf) return buf; } -static void blk_register_region(struct gendisk *disk) -{ - int i; - - mutex_lock(&bdev_map_lock); - 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); -} - -static void blk_unregister_region(struct gendisk *disk) -{ - int i; - - mutex_lock(&bdev_map_lock); - for (i = 0; i < disk->minors; i++) - xa_erase(&bdev_map, disk_devt(disk) + i); - mutex_unlock(&bdev_map_lock); -} - static void disk_scan_partitions(struct gendisk *disk) { struct block_device *bdev; @@ -805,7 +750,7 @@ 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); + bdev_add(disk->part0.bdev, devt); } register_disk(parent, disk, groups); if (register_queue) @@ -886,11 +831,8 @@ void del_gendisk(struct gendisk *disk) blk_integrity_del(disk); disk_del_events(disk); - /* - * Block lookups of the disk until all bdevs are unhashed and the - * disk is marked as dead (GENHD_FL_UP cleared). - */ - down_write(&disk->lookup_sem); + disk->flags &= ~GENHD_FL_UP; + /* invalidate stuff */ disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY | DISK_PITER_REVERSE); @@ -902,8 +844,6 @@ void del_gendisk(struct gendisk *disk) invalidate_partition(disk, 0); set_capacity(disk, 0); - disk->flags &= ~GENHD_FL_UP; - up_write(&disk->lookup_sem); if (!(disk->flags & GENHD_FL_HIDDEN)) { sysfs_remove_link(&disk_to_dev(disk)->kobj, "bdi"); @@ -916,16 +856,6 @@ void del_gendisk(struct gendisk *disk) } blk_unregister_queue(disk); - - if (!(disk->flags & GENHD_FL_HIDDEN)) - 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 - * use-after-free issues. Note that the device number stays - * "in-use" until we really free the gendisk. - */ - blk_invalidate_devt(disk_devt(disk)); kobject_put(disk->part0.holder_dir); kobject_put(disk->slave_dir); @@ -964,7 +894,7 @@ static ssize_t disk_badblocks_store(struct device *dev, return badblocks_store(disk->bb, page, len, 0); } -static void request_gendisk_module(dev_t devt) +void blk_request_module(dev_t devt) { unsigned int major = MAJOR(devt); struct blk_major_name **n; @@ -984,84 +914,6 @@ static void request_gendisk_module(dev_t devt) request_module("block-major-%d", MAJOR(devt)); } -static bool get_disk_and_module(struct gendisk *disk) -{ - struct module *owner; - - 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); - return false; - } - return true; - -} - -/** - * get_gendisk - get partitioning information for a given device - * @devt: device to get partitioning information for - * @partno: returned partition index - * - * This function gets the structure containing partitioning - * information for the given device @devt. - * - * Context: can sleep - */ -struct gendisk *get_gendisk(dev_t devt, int *partno) -{ - struct gendisk *disk = NULL; - - might_sleep(); - - if (MAJOR(devt) != BLOCK_EXT_MAJOR) { - 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; - - spin_lock_bh(&ext_devt_lock); - part = idr_find(&ext_devt_idr, blk_mangle_minor(MINOR(devt))); - if (part && get_disk_and_module(part_to_disk(part))) { - *partno = part->partno; - disk = part_to_disk(part); - } - spin_unlock_bh(&ext_devt_lock); - } - - if (!disk) - return NULL; - - /* - * Synchronize with del_gendisk() to not return disk that is being - * destroyed. - */ - down_read(&disk->lookup_sem); - if (unlikely((disk->flags & GENHD_FL_HIDDEN) || - !(disk->flags & GENHD_FL_UP))) { - up_read(&disk->lookup_sem); - put_disk_and_module(disk); - disk = NULL; - } else { - up_read(&disk->lookup_sem); - } - return disk; -} - /** * bdget_disk - do bdget() by gendisk and partition number * @disk: gendisk of interest @@ -1559,11 +1411,6 @@ int disk_expand_part_tbl(struct gendisk *disk, int partno) * * This function releases all allocated resources of the gendisk. * - * The struct gendisk refcount is incremented with get_gendisk() or - * get_disk_and_module(), and its refcount is decremented with - * put_disk_and_module() or put_disk(). Once the refcount reaches 0 this - * function is called. - * * Drivers which used __device_add_disk() have a gendisk with a request_queue * assigned. Since the request_queue sits on top of the gendisk for these * drivers we also call blk_put_queue() for them, and we expect the @@ -1585,7 +1432,7 @@ static void disk_release(struct device *dev) hd_free_part(&disk->part0); if (disk->queue) blk_put_queue(disk->queue); - kfree(disk); + kfree_rcu(disk, rcu); } struct class block_class = { .name = "block", @@ -1748,16 +1595,17 @@ struct gendisk *__alloc_disk_node(int minors, int node_id) if (!disk) return NULL; + disk->part0.bdev = bdev_alloc(disk, 0); + if (!disk->part0.bdev) + goto out_free_disk; + disk->part0.dkstats = alloc_percpu(struct disk_stats); if (!disk->part0.dkstats) - goto out_free_disk; + goto out_bdput; - init_rwsem(&disk->lookup_sem); disk->node_id = node_id; - if (disk_expand_part_tbl(disk, 0)) { - free_percpu(disk->part0.dkstats); - goto out_free_disk; - } + if (disk_expand_part_tbl(disk, 0)) + goto out_free_bdstats; ptbl = rcu_dereference_protected(disk->part_tbl, 1); rcu_assign_pointer(ptbl->part[0], &disk->part0); @@ -1773,7 +1621,7 @@ struct gendisk *__alloc_disk_node(int minors, int node_id) */ hd_sects_seq_init(&disk->part0); if (hd_ref_init(&disk->part0)) - goto out_free_part0; + goto out_free_bdstats; disk->minors = minors; rand_initialize_disk(disk); @@ -1782,8 +1630,10 @@ struct gendisk *__alloc_disk_node(int minors, int node_id) device_initialize(disk_to_dev(disk)); return disk; -out_free_part0: - hd_free_part(&disk->part0); +out_free_bdstats: + free_percpu(disk->part0.dkstats); +out_bdput: + bdput(disk->part0.bdev); out_free_disk: kfree(disk); return NULL; @@ -1807,26 +1657,6 @@ void put_disk(struct gendisk *disk) } EXPORT_SYMBOL(put_disk); -/** - * put_disk_and_module - decrements the module and gendisk refcount - * @disk: the struct gendisk to decrement the refcount for - * - * This is a counterpart of get_disk_and_module() and thus also of - * get_gendisk(). - * - * Context: Any context, but the last reference must not be dropped from - * atomic context. - */ -void put_disk_and_module(struct gendisk *disk) -{ - if (disk) { - struct module *owner = disk->fops->owner; - - put_disk(disk); - module_put(owner); - } -} - static void set_disk_ro_uevent(struct gendisk *gd, int ro) { char event[] = "DISK_RO=1"; diff --git a/block/partitions/core.c b/block/partitions/core.c index a02e224115943d..508b46da53eee5 100644 --- a/block/partitions/core.c +++ b/block/partitions/core.c @@ -340,12 +340,11 @@ void delete_partition(struct hd_struct *part) device_del(part_to_dev(part)); /* - * Remove gendisk pointer from idr so that it cannot be looked up - * while RCU period before freeing gendisk is running to prevent - * use-after-free issues. Note that the device number stays - * "in-use" until we really free the gendisk. + * Remove the block device from the inode hash, so that it cannot be + * looked up while waiting for the RCU grace period. */ - blk_invalidate_devt(part_devt(part)); + remove_inode_hash(part->bdev->bd_inode); + percpu_ref_kill(&part->ref); } @@ -368,6 +367,7 @@ static struct hd_struct *add_partition(struct gendisk *disk, int partno, dev_t devt = MKDEV(0, 0); struct device *ddev = disk_to_dev(disk); struct device *pdev; + struct block_device *bdev; struct disk_part_tbl *ptbl; const char *dname; int err; @@ -402,11 +402,15 @@ static struct hd_struct *add_partition(struct gendisk *disk, int partno, if (!p) return ERR_PTR(-EBUSY); + err = -ENOMEM; p->dkstats = alloc_percpu(struct disk_stats); - if (!p->dkstats) { - err = -ENOMEM; + if (!p->dkstats) goto out_free; - } + + bdev = bdev_alloc(disk, partno); + if (!bdev) + goto out_free_stats; + p->bdev = bdev; hd_sects_seq_init(p); pdev = part_to_dev(p); @@ -420,10 +424,8 @@ static struct hd_struct *add_partition(struct gendisk *disk, int partno, struct partition_meta_info *pinfo; pinfo = kzalloc_node(sizeof(*pinfo), GFP_KERNEL, disk->node_id); - if (!pinfo) { - err = -ENOMEM; - goto out_free_stats; - } + if (!pinfo) + goto out_bdput; memcpy(pinfo, info, sizeof(*info)); p->info = pinfo; } @@ -470,6 +472,7 @@ static struct hd_struct *add_partition(struct gendisk *disk, int partno, } /* everything is up and running, commence */ + bdev_add(bdev, devt); rcu_assign_pointer(ptbl->part[partno], p); /* suppress uevent if the disk suppresses it */ @@ -479,6 +482,8 @@ static struct hd_struct *add_partition(struct gendisk *disk, int partno, out_free_info: kfree(p->info); +out_bdput: + bdput(bdev); out_free_stats: free_percpu(p->dkstats); out_free: diff --git a/fs/block_dev.c b/fs/block_dev.c index c0d1e8248ffe23..b9ee8fe5acd570 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -863,31 +863,45 @@ void __init bdev_cache_init(void) blockdev_superblock = bd_mnt->mnt_sb; /* For writeback */ } -static struct block_device *bdget(dev_t dev) +struct block_device *bdev_alloc(struct gendisk *disk, u8 partno) { struct block_device *bdev; struct inode *inode; - inode = iget_locked(blockdev_superblock, dev); + inode = new_inode(blockdev_superblock); if (!inode) return NULL; + inode->i_mode = S_IFBLK; + inode->i_rdev = 0; + inode->i_data.a_ops = &def_blk_aops; + + bdev = I_BDEV(inode); + spin_lock_init(&bdev->bd_size_lock); + bdev->bd_disk = disk; + bdev->bd_partno = partno; + bdev->bd_contains = NULL; + bdev->bd_super = NULL; + bdev->bd_inode = inode; + bdev->bd_part_count = 0; + return bdev; +} - bdev = &BDEV_I(inode)->bdev; +void bdev_add(struct block_device *bdev, dev_t dev) +{ + bdev->bd_dev = dev; + bdev->bd_inode->i_rdev = dev; + bdev->bd_inode->i_ino = dev; + insert_inode_hash(bdev->bd_inode); +} - if (inode->i_state & I_NEW) { - spin_lock_init(&bdev->bd_size_lock); - bdev->bd_contains = NULL; - bdev->bd_super = NULL; - bdev->bd_inode = inode; - bdev->bd_part_count = 0; - bdev->bd_dev = dev; - inode->i_mode = S_IFBLK; - inode->i_rdev = dev; - inode->i_data.a_ops = &def_blk_aops; - mapping_set_gfp_mask(&inode->i_data, GFP_USER); - unlock_new_inode(inode); - } - return bdev; +static struct block_device *bdget(dev_t dev) +{ + struct inode *inode; + + inode = ilookup(blockdev_superblock, dev); + if (!inode) + return NULL; + return &BDEV_I(inode)->bdev; } /** @@ -1000,27 +1014,6 @@ int bd_prepare_to_claim(struct block_device *bdev, struct block_device *whole, } EXPORT_SYMBOL_GPL(bd_prepare_to_claim); /* only for the loop driver */ -static struct gendisk *bdev_get_gendisk(struct block_device *bdev, int *partno) -{ - struct gendisk *disk = get_gendisk(bdev->bd_dev, partno); - - if (!disk) - return NULL; - /* - * Now that we hold gendisk reference we make sure bdev we looked up is - * not stale. If it is, it means device got removed and created before - * we looked up gendisk and we fail open in such case. Associating - * unhashed bdev with newly created gendisk could lead to two bdevs - * (and thus two independent caches) being associated with one device - * which is bad. - */ - if (inode_unhashed(bdev->bd_inode)) { - put_disk_and_module(disk); - return NULL; - } - return disk; -} - static void bd_clear_claiming(struct block_device *whole, void *holder) { lockdep_assert_held(&bdev_lock); @@ -1343,19 +1336,17 @@ EXPORT_SYMBOL_GPL(bdev_disk_changed); * mutex_lock(part->bd_mutex) * mutex_lock_nested(whole->bd_mutex, 1) */ -static int __blkdev_get(struct block_device *bdev, struct gendisk *disk, - int partno, fmode_t mode) +static int __blkdev_get(struct block_device *bdev, fmode_t mode) { + struct gendisk *disk = bdev->bd_disk; int ret; if (!bdev->bd_openers) { - bdev->bd_disk = disk; bdev->bd_contains = bdev; - bdev->bd_partno = partno; - if (!partno) { + if (!bdev->bd_partno) { ret = -ENXIO; - bdev->bd_part = disk_get_part(disk, partno); + bdev->bd_part = disk_get_part(disk, 0); if (!bdev->bd_part) goto out_clear; @@ -1384,7 +1375,7 @@ static int __blkdev_get(struct block_device *bdev, struct gendisk *disk, struct block_device *whole = bdget_disk(disk, 0); mutex_lock_nested(&whole->bd_mutex, 1); - ret = __blkdev_get(whole, disk, 0, mode); + ret = __blkdev_get(whole, mode); if (ret) { mutex_unlock(&whole->bd_mutex); bdput(whole); @@ -1394,9 +1385,8 @@ static int __blkdev_get(struct block_device *bdev, struct gendisk *disk, mutex_unlock(&whole->bd_mutex); bdev->bd_contains = whole; - bdev->bd_part = disk_get_part(disk, partno); - if (!(disk->flags & GENHD_FL_UP) || - !bdev->bd_part || !bdev->bd_part->nr_sects) { + bdev->bd_part = disk_get_part(disk, bdev->bd_partno); + if (!bdev->bd_part || !bdev->bd_part->nr_sects) { __blkdev_put(whole, mode, 1); ret = -ENXIO; goto out_clear; @@ -1425,12 +1415,46 @@ static int __blkdev_get(struct block_device *bdev, struct gendisk *disk, out_clear: disk_put_part(bdev->bd_part); - bdev->bd_disk = NULL; bdev->bd_part = NULL; bdev->bd_contains = NULL; return ret; } +static struct block_device *get_bdev_disk_and_module(dev_t dev) +{ + struct block_device *bdev = NULL; + struct gendisk *disk = NULL; + + rcu_read_lock(); + bdev = bdget(dev); + if (!bdev) { + rcu_read_unlock(); + blk_request_module(dev); + rcu_read_lock(); + + bdev = bdget(dev); + } + if (!bdev) + goto fail; + + if (!kobject_get_unless_zero(&disk_to_dev(bdev->bd_disk)->kobj)) + goto fail; + disk = bdev->bd_disk; + if ((disk->flags & (GENHD_FL_UP | GENHD_FL_HIDDEN)) != GENHD_FL_UP) + goto fail; + if (!try_module_get(bdev->bd_disk->fops->owner)) + goto fail; + rcu_read_unlock(); + return bdev; +fail: + rcu_read_unlock(); + if (disk) + put_disk(disk); + if (bdev) + bdput(bdev); + return NULL; +} + /** * blkdev_get_by_dev - open a block device by device number * @dev: device number of block device to open @@ -1458,7 +1482,6 @@ struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder) bool unblock_events = true; struct block_device *bdev; struct gendisk *disk; - int partno; int ret; ret = devcgroup_check_permission(DEVCG_DEV_BLOCK, @@ -1468,19 +1491,15 @@ struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder) if (ret) return ERR_PTR(ret); - bdev = bdget(dev); - if (!bdev) - return ERR_PTR(-ENOMEM); - /* * If we lost a race with 'disk' being deleted, try again. See md.c. */ retry: - ret = -ENXIO; - disk = bdev_get_gendisk(bdev, &partno); - if (!disk) - goto bdput; - + bdev = get_bdev_disk_and_module(dev); + if (!bdev) + return ERR_PTR(-ENXIO); + disk = bdev->bd_disk; + if (mode & FMODE_EXCL) { WARN_ON_ONCE(!holder); @@ -1496,12 +1515,10 @@ struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder) disk_block_events(disk); mutex_lock(&bdev->bd_mutex); - ret =__blkdev_get(bdev, disk, partno, mode); - if (!(mode & FMODE_EXCL)) { - ; /* nothing to do here */ - } else if (ret) { - bd_abort_claiming(bdev, claiming, holder); - } else { + ret =__blkdev_get(bdev, mode); + if (ret) + goto abort_claiming; + if (mode & FMODE_EXCL) { bd_finish_claiming(bdev, claiming, holder); /* @@ -1521,21 +1538,25 @@ struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder) if (unblock_events) disk_unblock_events(disk); + if (mode & FMODE_EXCL) + bdput(claiming); + return bdev; +abort_claiming: + if (mode & FMODE_EXCL) + bd_abort_claiming(bdev, claiming, holder); + mutex_unlock(&bdev->bd_mutex); + disk_unblock_events(disk); put_claiming: if (mode & FMODE_EXCL) bdput(claiming); put_disk: - if (ret) - put_disk_and_module(disk); + module_put(disk->fops->owner); + put_disk(disk); + bdput(bdev); if (ret == -ERESTARTSYS) goto retry; -bdput: - if (ret) { - bdput(bdev); - return ERR_PTR(ret); - } - return bdev; + return ERR_PTR(ret); } EXPORT_SYMBOL(blkdev_get_by_dev); @@ -1637,7 +1658,6 @@ static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part) disk_put_part(bdev->bd_part); bdev->bd_part = NULL; - bdev->bd_disk = NULL; if (bdev_is_partition(bdev)) victim = bdev->bd_contains; bdev->bd_contains = NULL; @@ -1698,7 +1718,8 @@ void blkdev_put(struct block_device *bdev, fmode_t mode) mutex_unlock(&bdev->bd_mutex); __blkdev_put(bdev, mode, 0); - put_disk_and_module(disk); + module_put(disk->fops->owner); + put_disk(disk); } EXPORT_SYMBOL(blkdev_put); diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index bdd7339bcda462..48e5a8393cd793 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -1994,6 +1994,8 @@ void bd_abort_claiming(struct block_device *bdev, struct block_device *whole, void *holder); void blkdev_put(struct block_device *bdev, fmode_t mode); +struct block_device *bdev_alloc(struct gendisk *disk, u8 partno); +void bdev_add(struct block_device *bdev, dev_t dev); struct block_device *I_BDEV(struct inode *inode); struct block_device *bdget_part(struct hd_struct *part); struct block_device *bdgrab(struct block_device *bdev); diff --git a/include/linux/genhd.h b/include/linux/genhd.h index ca5e356084c353..d068e46f9086ae 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -65,6 +65,7 @@ struct hd_struct { struct disk_stats __percpu *dkstats; struct percpu_ref ref; + struct block_device *bdev; struct device __dev; struct kobject *holder_dir; int policy, partno; @@ -193,7 +194,6 @@ struct gendisk { int flags; unsigned long state; #define GD_NEED_PART_SCAN 0 - struct rw_semaphore lookup_sem; struct kobject *slave_dir; struct timer_rand_state *random; @@ -207,6 +207,7 @@ struct gendisk { #endif int node_id; struct badblocks *bb; + struct rcu_head rcu; struct lockdep_map lockdep_map; }; @@ -300,7 +301,6 @@ static inline void add_disk_no_queue_reg(struct gendisk *disk) } extern void del_gendisk(struct gendisk *gp); -extern struct gendisk *get_gendisk(dev_t dev, int *partno); extern struct block_device *bdget_disk(struct gendisk *disk, int partno); extern void set_disk_ro(struct gendisk *disk, int flag); @@ -338,7 +338,6 @@ int blk_drop_partitions(struct block_device *bdev); extern struct gendisk *__alloc_disk_node(int minors, int node_id); extern void put_disk(struct gendisk *disk); -extern void put_disk_and_module(struct gendisk *disk); #define alloc_disk_node(minors, node_id) \ ({ \ @@ -389,6 +388,7 @@ static inline void bd_unlink_disk_holder(struct block_device *bdev, #endif /* CONFIG_SYSFS */ dev_t blk_lookup_devt(const char *name, int partno); +void blk_request_module(dev_t devt); #ifdef CONFIG_BLOCK void printk_all_partitions(void); #else /* CONFIG_BLOCK */