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>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/ide/ide-cd.c b/drivers/ide/ide-cd.c
index 0bfeb0c79d6e..690475b834de 100644
--- 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);