3 files changed, 41 insertions, 2 deletions

diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index 6957350e122..9de31bc98c8 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -131,6 +131,7 @@ struct hd_struct {
 #define GENHD_FL_EXT_DEVT                       64 /* allow extended devt */
 #define GENHD_FL_NATIVE_CAPACITY                128
 #define GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE     256
+#define GENHD_FL_NO_PART_SCAN                   512
 
 enum {
         DISK_EVENT_MEDIA_CHANGE                 = 1 << 0, /* media changed */
@@ -238,9 +239,10 @@ static inline int disk_max_parts(struct gendisk *disk)
         return disk->minors;
 }
 
-static inline bool disk_partitionable(struct gendisk *disk)
+static inline bool disk_part_scan_enabled(struct gendisk *disk)
 {
-        return disk_max_parts(disk) > 1;
+        return disk_max_parts(disk) > 1 &&
+                !(disk->flags & GENHD_FL_NO_PART_SCAN);
 }
 
 static inline dev_t disk_devt(struct gendisk *disk)
diff --git a/include/linux/loop.h b/include/linux/loop.h
index a0688068911..11a41a8f08e 100644
--- a/include/linux/loop.h
+++ b/include/linux/loop.h
@@ -74,6 +74,7 @@ struct loop_device {
 enum {
         LO_FLAGS_READ_ONLY      = 1,
         LO_FLAGS_AUTOCLEAR      = 4,
+        LO_FLAGS_PARTSCAN       = 8,
 };
 
 #include <asm/posix_types.h>    /* for __kernel_old_dev_t */
diff --git a/include/xen/interface/io/blkif.h b/include/xen/interface/io/blkif.h
index 3d5d6db864f..9324488f23f 100644
--- a/include/xen/interface/io/blkif.h
+++ b/include/xen/interface/io/blkif.h
@@ -57,6 +57,36 @@ typedef uint64_t blkif_sector_t;
  * "feature-flush-cache" node!
  */
 #define BLKIF_OP_FLUSH_DISKCACHE   3
+
+/*
+ * Recognised only if "feature-discard" is present in backend xenbus info.
+ * The "feature-discard" node contains a boolean indicating whether trim
+ * (ATA) or unmap (SCSI) - conviently called discard requests are likely
+ * to succeed or fail. Either way, a discard request
+ * may fail at any time with BLKIF_RSP_EOPNOTSUPP if it is unsupported by
+ * the underlying block-device hardware. The boolean simply indicates whether
+ * or not it is worthwhile for the frontend to attempt discard requests.
+ * If a backend does not recognise BLKIF_OP_DISCARD, it should *not*
+ * create the "feature-discard" node!
+ *
+ * Discard operation is a request for the underlying block device to mark
+ * extents to be erased. However, discard does not guarantee that the blocks
+ * will be erased from the device - it is just a hint to the device
+ * controller that these blocks are no longer in use. What the device
+ * controller does with that information is left to the controller.
+ * Discard operations are passed with sector_number as the
+ * sector index to begin discard operations at and nr_sectors as the number of
+ * sectors to be discarded. The specified sectors should be discarded if the
+ * underlying block device supports trim (ATA) or unmap (SCSI) operations,
+ * or a BLKIF_RSP_EOPNOTSUPP  should be returned.
+ * More information about trim/unmap operations at:
+ * http://t13.org/Documents/UploadedDocuments/docs2008/
+ *     e07154r6-Data_Set_Management_Proposal_for_ATA-ACS2.doc
+ * http://www.seagate.com/staticfiles/support/disc/manuals/
+ *     Interface%20manuals/100293068c.pdf
+ */
+#define BLKIF_OP_DISCARD           5
+
 /*
  * Maximum scatter/gather segments per request.
  * This is carefully chosen so that sizeof(struct blkif_ring) <= PAGE_SIZE.
@@ -74,6 +104,11 @@ struct blkif_request_rw {
         } seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
 };
 
+struct blkif_request_discard {
+        blkif_sector_t sector_number;
+        uint64_t nr_sectors;
+};
+
 struct blkif_request {
         uint8_t        operation;    /* BLKIF_OP_???                         */
         uint8_t        nr_segments;  /* number of segments                   */
@@ -81,6 +116,7 @@ struct blkif_request {
         uint64_t       id;           /* private guest value, echoed in resp  */
         union {
                 struct blkif_request_rw rw;
+                struct blkif_request_discard discard;
         } u;
 };