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Date: Sun, 30 Aug 2020 08:24:32 +0200 From: Christoph Hellwig <hch@....de> To: Jens Axboe <axboe@...nel.dk> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, "Rafael J. Wysocki" <rafael@...nel.org>, Denis Efremov <efremov@...ux.com>, "David S. Miller" <davem@...emloft.net>, Song Liu <song@...nel.org>, Al Viro <viro@...iv.linux.org.uk>, linux-block@...r.kernel.org, linux-kernel@...r.kernel.org, linux-ide@...r.kernel.org, linux-raid@...r.kernel.org, linux-scsi@...r.kernel.org, linux-m68k@...ts.linux-m68k.org Subject: [PATCH 06/19] block: add an optional probe callback to major_names Add a callback to the major_names array that allows a driver to override how to probe for dev_t that doesn't currently have a gendisk registered. This will help separating the lookup of the gendisk by dev_t vs probe action for a not currently registered dev_t. Signed-off-by: Christoph Hellwig <hch@....de> --- block/genhd.c | 21 ++++++++++++++++++--- include/linux/genhd.h | 5 ++++- 2 files changed, 22 insertions(+), 4 deletions(-) diff --git a/block/genhd.c b/block/genhd.c index 00164304317cfa..4cbeff3ec1ef5a 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -402,6 +402,7 @@ static struct blk_major_name { struct blk_major_name *next; int major; char name[16]; + void (*probe)(dev_t devt); } *major_names[BLKDEV_MAJOR_HASH_SIZE]; static DEFINE_MUTEX(major_names_lock); @@ -444,7 +445,8 @@ void blkdev_show(struct seq_file *seqf, off_t offset) * See Documentation/admin-guide/devices.txt for the list of allocated * major numbers. */ -int register_blkdev(unsigned int major, const char *name) +int __register_blkdev(unsigned int major, const char *name, + void (*probe)(dev_t devt)) { struct blk_major_name **n, *p; int index, ret = 0; @@ -483,6 +485,7 @@ int register_blkdev(unsigned int major, const char *name) } p->major = major; + p->probe = probe; strlcpy(p->name, name, sizeof(p->name)); p->next = NULL; index = major_to_index(major); @@ -505,8 +508,7 @@ int register_blkdev(unsigned int major, const char *name) mutex_unlock(&major_names_lock); return ret; } - -EXPORT_SYMBOL(register_blkdev); +EXPORT_SYMBOL(__register_blkdev); void unregister_blkdev(unsigned int major, const char *name) { @@ -1037,6 +1039,19 @@ static ssize_t disk_badblocks_store(struct device *dev, static void request_gendisk_module(dev_t devt) { + unsigned int major = MAJOR(devt); + struct blk_major_name **n; + + mutex_lock(&major_names_lock); + for (n = &major_names[major_to_index(major)]; *n; n = &(*n)->next) { + if ((*n)->major == major && (*n)->probe) { + (*n)->probe(devt); + mutex_unlock(&major_names_lock); + return; + } + } + mutex_unlock(&major_names_lock); + if (request_module("block-major-%d-%d", MAJOR(devt), MINOR(devt)) > 0) /* Make old-style 2.4 aliases work */ request_module("block-major-%d", MAJOR(devt)); diff --git a/include/linux/genhd.h b/include/linux/genhd.h index 4ab853461dff25..c0bde190a3dd0c 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -369,7 +369,10 @@ extern void blk_unregister_region(dev_t devt, unsigned long range); #define alloc_disk(minors) alloc_disk_node(minors, NUMA_NO_NODE) -int register_blkdev(unsigned int major, const char *name); +int __register_blkdev(unsigned int major, const char *name, + void (*probe)(dev_t devt)); +#define register_blkdev(major, name) \ + __register_blkdev(major, name, NULL) void unregister_blkdev(unsigned int major, const char *name); int revalidate_disk(struct gendisk *disk); -- 2.28.0
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