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virtio_blk: Add 'serial' attribute to virtio-blk devices (v2)

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Create a new attribute for virtio-blk devices that will fetch the serial number
of the block device.  This attribute can be used by udev to create disk/by-id
symlinks for devices that don't have a UUID (filesystem) associated with them.

ATA_IDENTIFY strings are special in that they can be up to 20 chars long
and aren't required to be nul-terminated.  The buffer is also zero-padded
meaning that if the serial is 19 chars or less that we get a nul-terminated
string.  When copying this value into a string buffer, we must be careful to
copy up to the nul (if it present) and only 20 if it is longer and not to
attempt to nul terminate; this isn't needed.

Changes since v1:
- Added BUILD_BUG_ON() for PAGE_SIZE check
- Removed min() since BUILD_BUG_ON() handles the check
- Replaced serial_sysfs() by copying id directly to buffer

Signed-off-by: Ryan Harper <ryanh@us.ibm.com>
Signed-off-by: john cooper <john.cooper@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Ryan Harper 2010-06-23 22:19:57 -05:00 committed by Rusty Russell
parent 10bc310c27
commit a5eb9e4ff1
1 changed files with 28 additions and 0 deletions
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28
drivers/block/virtio_blk.c
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@ -281,6 +281,27 @@ static int index_to_minor(int index)
return index << PART_BITS;
}
static ssize_t virtblk_serial_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct gendisk *disk = dev_to_disk(dev);
int err;
/* sysfs gives us a PAGE_SIZE buffer */
BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES);
buf[VIRTIO_BLK_ID_BYTES] = '\0';
err = virtblk_get_id(disk, buf);
if (!err)
return strlen(buf);
if (err == -EIO) /* Unsupported? Make it empty. */
return 0;
return err;
}
DEVICE_ATTR(serial, S_IRUGO, virtblk_serial_show, NULL);
static int __devinit virtblk_probe(struct virtio_device *vdev)
{
struct virtio_blk *vblk;
@ -465,8 +486,15 @@ static int __devinit virtblk_probe(struct virtio_device *vdev)
add_disk(vblk->disk);
err = device_create_file(disk_to_dev(vblk->disk), &dev_attr_serial);
if (err)
goto out_del_disk;
return 0;
out_del_disk:
del_gendisk(vblk->disk);
blk_cleanup_queue(vblk->disk->queue);
out_put_disk:
put_disk(vblk->disk);
out_mempool: