From 517bf3c306bad4fe0da631f90ae2ec40924dee2b Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Thu, 2 Nov 2017 21:29:52 +0300 Subject: block: don't look at the struct device dev_t in disk_devt The hidden gendisks introduced in the next patch need to keep the dev field in their struct device empty so that udev won't try to create block device nodes for them. To support that rewrite disk_devt to look at the major and first_minor fields in the gendisk itself instead of looking into the struct device. Signed-off-by: Christoph Hellwig Reviewed-by: Johannes Thumshirn Reviewed-by: Hannes Reinecke Signed-off-by: Jens Axboe --- block/genhd.c | 4 ---- 1 file changed, 4 deletions(-) (limited to 'block/genhd.c') diff --git a/block/genhd.c b/block/genhd.c index dd305c65ffb05..1174d24e405ee 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -649,10 +649,6 @@ void device_add_disk(struct device *parent, struct gendisk *disk) return; } disk_to_dev(disk)->devt = devt; - - /* ->major and ->first_minor aren't supposed to be - * dereferenced from here on, but set them just in case. - */ disk->major = MAJOR(devt); disk->first_minor = MINOR(devt); -- cgit v1.2.3 From 8ddcd653257c18a669fcb75ee42c37054908e0d6 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Thu, 2 Nov 2017 21:29:53 +0300 Subject: block: introduce GENHD_FL_HIDDEN With this flag a driver can create a gendisk that can be used for I/O submission inside the kernel, but which is not registered as user facing block device. This will be useful for the NVMe multipath implementation. Signed-off-by: Christoph Hellwig Signed-off-by: Jens Axboe --- block/genhd.c | 68 +++++++++++++++++++++++++++++++++++++-------------- include/linux/genhd.h | 1 + 2 files changed, 51 insertions(+), 18 deletions(-) (limited to 'block/genhd.c') diff --git a/block/genhd.c b/block/genhd.c index 1174d24e405ee..835e907e6e015 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -585,6 +585,11 @@ static void register_disk(struct device *parent, struct gendisk *disk) */ pm_runtime_set_memalloc_noio(ddev, true); + if (disk->flags & GENHD_FL_HIDDEN) { + dev_set_uevent_suppress(ddev, 0); + return; + } + disk->part0.holder_dir = kobject_create_and_add("holders", &ddev->kobj); disk->slave_dir = kobject_create_and_add("slaves", &ddev->kobj); @@ -616,6 +621,11 @@ exit: while ((part = disk_part_iter_next(&piter))) kobject_uevent(&part_to_dev(part)->kobj, KOBJ_ADD); disk_part_iter_exit(&piter); + + err = sysfs_create_link(&ddev->kobj, + &disk->queue->backing_dev_info->dev->kobj, + "bdi"); + WARN_ON(err); } /** @@ -630,7 +640,6 @@ exit: */ void device_add_disk(struct device *parent, struct gendisk *disk) { - struct backing_dev_info *bdi; dev_t devt; int retval; @@ -639,7 +648,8 @@ void device_add_disk(struct device *parent, struct gendisk *disk) * parameters make sense. */ WARN_ON(disk->minors && !(disk->major || disk->first_minor)); - WARN_ON(!disk->minors && !(disk->flags & GENHD_FL_EXT_DEVT)); + WARN_ON(!disk->minors && + !(disk->flags & (GENHD_FL_EXT_DEVT | GENHD_FL_HIDDEN))); disk->flags |= GENHD_FL_UP; @@ -648,18 +658,26 @@ void device_add_disk(struct device *parent, struct gendisk *disk) WARN_ON(1); return; } - disk_to_dev(disk)->devt = devt; disk->major = MAJOR(devt); disk->first_minor = MINOR(devt); disk_alloc_events(disk); - /* Register BDI before referencing it from bdev */ - bdi = disk->queue->backing_dev_info; - bdi_register_owner(bdi, disk_to_dev(disk)); - - blk_register_region(disk_devt(disk), disk->minors, NULL, - exact_match, exact_lock, disk); + if (disk->flags & GENHD_FL_HIDDEN) { + /* + * Don't let hidden disks show up in /proc/partitions, + * and don't bother scanning for partitions either. + */ + disk->flags |= GENHD_FL_SUPPRESS_PARTITION_INFO; + disk->flags |= GENHD_FL_NO_PART_SCAN; + } else { + /* Register BDI before referencing it from bdev */ + disk_to_dev(disk)->devt = devt; + bdi_register_owner(disk->queue->backing_dev_info, + disk_to_dev(disk)); + blk_register_region(disk_devt(disk), disk->minors, NULL, + exact_match, exact_lock, disk); + } register_disk(parent, disk); blk_register_queue(disk); @@ -669,10 +687,6 @@ void device_add_disk(struct device *parent, struct gendisk *disk) */ WARN_ON_ONCE(!blk_get_queue(disk->queue)); - retval = sysfs_create_link(&disk_to_dev(disk)->kobj, &bdi->dev->kobj, - "bdi"); - WARN_ON(retval); - disk_add_events(disk); blk_integrity_add(disk); } @@ -701,7 +715,8 @@ void del_gendisk(struct gendisk *disk) set_capacity(disk, 0); disk->flags &= ~GENHD_FL_UP; - sysfs_remove_link(&disk_to_dev(disk)->kobj, "bdi"); + if (!(disk->flags & GENHD_FL_HIDDEN)) + sysfs_remove_link(&disk_to_dev(disk)->kobj, "bdi"); if (disk->queue) { /* * Unregister bdi before releasing device numbers (as they can @@ -712,13 +727,15 @@ void del_gendisk(struct gendisk *disk) } else { WARN_ON(1); } - blk_unregister_region(disk_devt(disk), disk->minors); + + if (!(disk->flags & GENHD_FL_HIDDEN)) { + blk_unregister_region(disk_devt(disk), disk->minors); + kobject_put(disk->part0.holder_dir); + kobject_put(disk->slave_dir); + } part_stat_set_all(&disk->part0, 0); disk->part0.stamp = 0; - - kobject_put(disk->part0.holder_dir); - kobject_put(disk->slave_dir); if (!sysfs_deprecated) sysfs_remove_link(block_depr, dev_name(disk_to_dev(disk))); pm_runtime_set_memalloc_noio(disk_to_dev(disk), false); @@ -781,6 +798,10 @@ struct gendisk *get_gendisk(dev_t devt, int *partno) spin_unlock_bh(&ext_devt_lock); } + if (unlikely(disk->flags & GENHD_FL_HIDDEN)) { + put_disk(disk); + disk = NULL; + } return disk; } EXPORT_SYMBOL(get_gendisk); @@ -1024,6 +1045,15 @@ static ssize_t disk_removable_show(struct device *dev, (disk->flags & GENHD_FL_REMOVABLE ? 1 : 0)); } +static ssize_t disk_hidden_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct gendisk *disk = dev_to_disk(dev); + + return sprintf(buf, "%d\n", + (disk->flags & GENHD_FL_HIDDEN ? 1 : 0)); +} + static ssize_t disk_ro_show(struct device *dev, struct device_attribute *attr, char *buf) { @@ -1061,6 +1091,7 @@ static ssize_t disk_discard_alignment_show(struct device *dev, static DEVICE_ATTR(range, S_IRUGO, disk_range_show, NULL); static DEVICE_ATTR(ext_range, S_IRUGO, disk_ext_range_show, NULL); static DEVICE_ATTR(removable, S_IRUGO, disk_removable_show, NULL); +static DEVICE_ATTR(hidden, S_IRUGO, disk_hidden_show, NULL); static DEVICE_ATTR(ro, S_IRUGO, disk_ro_show, NULL); static DEVICE_ATTR(size, S_IRUGO, part_size_show, NULL); static DEVICE_ATTR(alignment_offset, S_IRUGO, disk_alignment_offset_show, NULL); @@ -1085,6 +1116,7 @@ static struct attribute *disk_attrs[] = { &dev_attr_range.attr, &dev_attr_ext_range.attr, &dev_attr_removable.attr, + &dev_attr_hidden.attr, &dev_attr_ro.attr, &dev_attr_size.attr, &dev_attr_alignment_offset.attr, diff --git a/include/linux/genhd.h b/include/linux/genhd.h index 5c0ed5db33c2d..93aae3476f58b 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -140,6 +140,7 @@ struct hd_struct { #define GENHD_FL_NATIVE_CAPACITY 128 #define GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE 256 #define GENHD_FL_NO_PART_SCAN 512 +#define GENHD_FL_HIDDEN 1024 enum { DISK_EVENT_MEDIA_CHANGE = 1 << 0, /* media changed */ -- cgit v1.2.3 From 17eac0996341cfd28b4093554e662fd82aa1c237 Mon Sep 17 00:00:00 2001 From: Hannes Reinecke Date: Thu, 9 Nov 2017 17:57:06 +0100 Subject: block: create 'slaves' and 'holders' entries for hidden gendisks When creating nvme multipath devices we should populate the 'slaves' and 'holders' directorys properly to aid userspace topology detection. Signed-off-by: Hannes Reinecke [hch: split from a larger patch] Reviewed-by: Keith Busch Reviewed-by: Martin K. Petersen Signed-off-by: Christoph Hellwig Signed-off-by: Jens Axboe --- block/genhd.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) (limited to 'block/genhd.c') diff --git a/block/genhd.c b/block/genhd.c index 835e907e6e015..3de1671631bfd 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -585,14 +585,14 @@ static void register_disk(struct device *parent, struct gendisk *disk) */ pm_runtime_set_memalloc_noio(ddev, true); + disk->part0.holder_dir = kobject_create_and_add("holders", &ddev->kobj); + disk->slave_dir = kobject_create_and_add("slaves", &ddev->kobj); + if (disk->flags & GENHD_FL_HIDDEN) { dev_set_uevent_suppress(ddev, 0); return; } - disk->part0.holder_dir = kobject_create_and_add("holders", &ddev->kobj); - disk->slave_dir = kobject_create_and_add("slaves", &ddev->kobj); - /* No minors to use for partitions */ if (!disk_part_scan_enabled(disk)) goto exit; @@ -728,11 +728,11 @@ void del_gendisk(struct gendisk *disk) WARN_ON(1); } - if (!(disk->flags & GENHD_FL_HIDDEN)) { + if (!(disk->flags & GENHD_FL_HIDDEN)) blk_unregister_region(disk_devt(disk), disk->minors); - kobject_put(disk->part0.holder_dir); - kobject_put(disk->slave_dir); - } + + kobject_put(disk->part0.holder_dir); + kobject_put(disk->slave_dir); part_stat_set_all(&disk->part0, 0); disk->part0.stamp = 0; -- cgit v1.2.3 From f0fba398fec65ff5a2e1bf8ae62718ec0450abaf Mon Sep 17 00:00:00 2001 From: Colin Ian King Date: Mon, 6 Nov 2017 17:53:53 +0000 Subject: block: avoid null pointer dereference on null disk It is possible that the pointer disk can be null and hence we can get a null pointer deference when accessing disk->flags. Add a null pointer check to avoid the dereference. Detected by CoverityScan, CID#1461133 ("Explicit null dereferenced") Fixes: 8ddcd653257c ("block: introduce GENHD_FL_HIDDEN") Reviewed-by: Christoph Hellwig Signed-off-by: Colin Ian King Signed-off-by: Jens Axboe --- block/genhd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'block/genhd.c') diff --git a/block/genhd.c b/block/genhd.c index 3de1671631bfd..997e598f3b86e 100644 --- a/block/genhd.c +++ b/block/genhd.c @@ -798,7 +798,7 @@ struct gendisk *get_gendisk(dev_t devt, int *partno) spin_unlock_bh(&ext_devt_lock); } - if (unlikely(disk->flags & GENHD_FL_HIDDEN)) { + if (disk && unlikely(disk->flags & GENHD_FL_HIDDEN)) { put_disk(disk); disk = NULL; } -- cgit v1.2.3