linux-kernel - [PATCH] block: hide badblocks attribute by default

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Message-ID: <149332958627.40858.3562179022452904734.stgit@dwillia2-desk3.amr.corp.intel.com>
Date:   Thu, 27 Apr 2017 14:46:26 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     axboe@...com
Cc:     linux-block@...r.kernel.org,
        Vishal Verma <vishal.l.verma@...el.com>,
        Christoph Hellwig <hch@....de>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] block: hide badblocks attribute by default

Commit 99e6608c9e74 "block: Add badblock management for gendisks"
allowed for drivers like pmem and software-raid to advertise a list of
bad media areas. However, it inadvertently added a 'badblocks' to all
block devices. Lets clean this up by having the 'badblocks' attribute
not be visible when the driver has not populated a 'struct badblocks'
instance in the gendisk.

Cc: Jens Axboe <axboe@...com>
Cc: Christoph Hellwig <hch@....de>
Cc: Martin K. Petersen <martin.petersen@...cle.com>
Reported-by: Vishal Verma <vishal.l.verma@...el.com>
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
---
 block/genhd.c |   11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/block/genhd.c b/block/genhd.c
index a9c516a8b37d..12acd48e1210 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1060,8 +1060,19 @@ static struct attribute *disk_attrs[] = {
 	NULL
 };
 
+static umode_t disk_visible(struct kobject *kobj, struct attribute *a, int n)
+{
+	struct device *dev = container_of(kobj, typeof(*dev), kobj);
+	struct gendisk *disk = dev_to_disk(dev);
+
+	if (a == &dev_attr_badblocks.attr && !disk->bb)
+		return 0;
+	return a->mode;
+}
+
 static struct attribute_group disk_attr_group = {
 	.attrs = disk_attrs,
+	.is_visible = disk_visible,
 };
 
 static const struct attribute_group *disk_attr_groups[] = {