Re: [PATCH 3/4] ide-gd: implement block device ->set_capacity method

Sergei Shtylyov
2009-06-02T18:54:48Z

Hello.

Bartlomiej Zolnierkiewicz wrote:

>>From: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
>>Subject: [PATCH] ide-gd: implement block device ->set_capacity method

>>* Use ->probed_capacity to store native device capacity for ATA disks.

>>* Add ->set_capacity method to struct ide_disk_ops.

>>* Implement disk device ->set_capacity method for ATA disks.

>>* Implement block device ->set_capacity method.

>>Together with the previous patch adding ->set_capacity block device
>>method this allows automatic disabling of Host Protected Area (HPA)
>>if any partitions overlapping HPA are detected.

>>Cc: Robert Hancock <hancockrwd@gmail.com>
>>Cc: Frans Pop <elendil@planet.nl>
>>Cc: "Andries E. Brouwer" <Andries.Brouwer@cwi.nl>
>>Cc: Al Viro <viro@zeniv.linux.org.uk>
>>Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

> v2 interdiff

> v2:
> * Check if LBA and HPA are supported in ide_disk_set_capacity().

> * According to the spec the SET MAX ADDRESS command shall be
> immediately preceded by a READ NATIVE MAX ADDRESS command.

> * Add ide_disk_hpa_{get_native,set}_capacity() helpers.

One of them seem to me pretty useless...

> diff -u b/drivers/ide/ide-disk.c b/drivers/ide/ide-disk.c
> --- b/drivers/ide/ide-disk.c
> +++ b/drivers/ide/ide-disk.c
> @@ -302,14 +302,12 @@
> { NULL, NULL }
> };
>
> -static void idedisk_check_hpa(ide_drive_t *drive)
> +static u64 ide_disk_hpa_get_native_capacity(ide_drive_t *drive, int lba48)

Frankly speaking, I don't see what you've bought with factoring out this
function...

> {
> - unsigned long long capacity, set_max;
> - int lba48 = ata_id_lba48_enabled(drive->id);
> + u64 capacity, set_max;
>
> capacity = drive->capacity64;
> -
> - set_max = idedisk_read_native_max_address(drive, lba48);
> + set_max = idedisk_read_native_max_address(drive, lba48);
>
> if (ide_in_drive_list(drive->id, hpa_list)) {
> /*
> @@ -320,6 +318,26 @@
> set_max--;
> }
>
> + return set_max;
> +}
> +
> +static u64 ide_disk_hpa_set_capacity(ide_drive_t *drive, u64 set_max, int lba48)
> +{
> + set_max = idedisk_set_max_address(drive, set_max, lba48);
> + if (set_max)
> + drive->capacity64 = set_max;
> +
> + return set_max;
> +}
> +
> +static void idedisk_check_hpa(ide_drive_t *drive)
> +{
> + u64 capacity, set_max;
> + int lba48 = ata_id_lba48_enabled(drive->id);
> +
> + capacity = drive->capacity64;
> + set_max = ide_disk_hpa_get_native_capacity(drive, lba48);
> +
> if (set_max <= capacity)
> return;
>
> @@ -332,13 +350,10 @@
> capacity, sectors_to_MB(capacity),
> set_max, sectors_to_MB(set_max));
>
> - set_max = idedisk_set_max_address(drive, set_max, lba48);
> -
> - if (set_max) {
> - drive->capacity64 = set_max;
> + set_max = ide_disk_hpa_set_capacity(drive, set_max, lba48);
> + if (set_max)
> printk(KERN_INFO "%s: Host Protected Area disabled.\n",
> drive->name);
> - }
> }
>
> static int ide_disk_get_capacity(ide_drive_t *drive)
> @@ -399,12 +414,25 @@
> static u64 ide_disk_set_capacity(ide_drive_t *drive, u64 capacity)
> {
> u64 set = min(capacity, drive->probed_capacity);
> - int lba48 = ata_id_lba48_enabled(drive->id);
> -
> - capacity = idedisk_set_max_address(drive, set, lba48);
> - if (capacity)
> - drive->capacity64 = capacity;
> + u16 *id = drive->id;
> + int lba48 = ata_id_lba48_enabled(id);
>
> + if ((drive->dev_flags & IDE_DFLAG_LBA) == 0 ||
> + ata_id_hpa_enabled(id) == 0)
> + goto out;
> +
> + /*
> + * according to the spec the SET MAX ADDRESS command shall be
> + * immediately preceded by a READ NATIVE MAX ADDRESS command
> + */
> + capacity = ide_disk_hpa_get_native_capacity(drive, lba48);

Might as well just call idedisk_read_native_max_address() -- we don't
need to lookup hpa_list[] if we're only checking whether we can read native
max address or not afterwards:

> + if (capacity == 0)
> + goto out;
> +
> + set = ide_disk_hpa_set_capacity(drive, set, lba48);
> + if (set)
> + return set;

Why bother doing that again if the function itself does such check and
sets drive->capacity64 to the returned value on success? It should be as
simple as:

ide_disk_hpa_set_capacity(drive, set, lba48);

> +out:
> return drive->capacity64;
> }

Label/gotos unnecessary in this case -- we have *return*...

MBR, Sergei