[SCSI] sd: tell the user when a disk's capacity is adjusted

This patch (as1188) combines the tests for decrementing a drive's
reported capacity and expands the comment.  It also adds an
informational message to the system log, informing the user when the
reported value has been changed.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 15 insertions, 11 deletions

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 4970ae4a62d6..e744ee40be69 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1383,18 +1383,22 @@ repeat:
                 sd_read_protection_type(sdkp, buffer);
         }       
 
-        /* Some devices return the total number of sectors, not the
-         * highest sector number.  Make the necessary adjustment. */
-        if (sdp->fix_capacity) {
+        /* Some devices are known to return the total number of blocks,
+         * not the highest block number.  Some devices have versions
+         * which do this and others which do not.  Some devices we might
+         * suspect of doing this but we don't know for certain.
+         *
+         * If we know the reported capacity is wrong, decrement it.  If
+         * we can only guess, then assume the number of blocks is even
+         * (usually true but not always) and err on the side of lowering
+         * the capacity.
+         */
+        if (sdp->fix_capacity ||
+            (sdp->guess_capacity && (sdkp->capacity & 0x01))) {
+                sd_printk(KERN_INFO, sdkp, "Adjusting the sector count "
+                                "from its reported value: %llu\n",
+                                (unsigned long long) sdkp->capacity);
                 --sdkp->capacity;
-
-        /* Some devices have version which report the correct sizes
-         * and others which do not. We guess size according to a heuristic
-         * and err on the side of lowering the capacity. */
-        } else {
-                if (sdp->guess_capacity)
-                        if (sdkp->capacity & 0x01) /* odd sizes are odd */
-                                --sdkp->capacity;
         }
 
 got_data: