ide-cd: document capacity hack

Just copy the comment from drivers/scsi/sr.c::sr_done()
(from which the capacity hack has been originated).

Cc: Borislav Petkov <petkovbb@gmail.com>
Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

diff --git a/drivers/ide/ide-cd.c b/drivers/ide/ide-cd.c
index 0bfeb0c79d6e8e172cdbb5fd3af9a9df084351c5..690475b834deff18c251ca1bf294d049a50451dc 100644 (file)
--- a/drivers/ide/ide-cd.c
+++ b/drivers/ide/ide-cd.c
@@ -194,6 +194,14 @@ static void cdrom_analyze_sense_data(ide_drive_t *drive,
                        bio_sectors = max(bio_sectors(failed_command->bio), 4U);
                        sector &= ~(bio_sectors - 1);
 
+                       /*
+                        * The SCSI specification allows for the value
+                        * returned by READ CAPACITY to be up to 75 2K
+                        * sectors past the last readable block.
+                        * Therefore, if we hit a medium error within the
+                        * last 75 2K sectors, we decrease the saved size
+                        * value.
+                        */
                        if (sector < get_capacity(info->disk) &&
                            drive->probed_capacity - sector < 4 * 75)
                                set_capacity(info->disk, sector);