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

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Hello.

Bartlomiej Zolnierkiewicz wrote:

From: Bartlomiej Zolnierkiewicz <bzolnier@xxxxxxxxx>
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@xxxxxxxxx>
Cc: Frans Pop <elendil@xxxxxxxxx>
Cc: "Andries E. Brouwer" <Andries.Brouwer@xxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@xxxxxxxxx>

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
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