[Xen-devel] [PATCH V2 1/3] xen-blkfront: add BLKIF_OP_TRIM and backend type flags

[Li Dongyang <lidongyang@xxxxxxxxxx>]

This adds the BLKIF_OP_TRIM for blkfront and blkback, also 2 flags telling
us the type of the backend, used in blkback to determine what to do when we
see a trim request.
Part of the patch is just taken from Owen Smith, Thanks

Signed-off-by: Owen Smith <owen.smith@xxxxxxxxxx>
Signed-off-by: Li Dongyang <lidongyang@xxxxxxxxxx>
---
 include/xen/interface/io/blkif.h |   21 +++++++++++++++++++++
 1 files changed, 21 insertions(+), 0 deletions(-)

diff --git a/include/xen/interface/io/blkif.h b/include/xen/interface/io/blkif.h
index 3d5d6db..b92cf23 100644
--- a/include/xen/interface/io/blkif.h
+++ b/include/xen/interface/io/blkif.h
@@ -57,6 +57,19 @@ typedef uint64_t blkif_sector_t;
  * "feature-flush-cache" node!
  */
 #define BLKIF_OP_FLUSH_DISKCACHE   3
+
+/*
+ * Recognised only if "feature-trim" is present in backend xenbus info.
+ * The "feature-trim" node contains a boolean indicating whether barrier
+ * requests are likely to succeed or fail. Either way, a trim 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 trim requests.
+ * If a backend does not recognise BLKIF_OP_TRIM, it should *not*
+ * create the "feature-trim" node!
+ */
+#define BLKIF_OP_TRIM            5
+
 /*
  * Maximum scatter/gather segments per request.
  * This is carefully chosen so that sizeof(struct blkif_ring) <= PAGE_SIZE.
@@ -74,6 +87,11 @@ struct blkif_request_rw {
        } seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
 };
 
+struct blkif_request_trim {
+       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 +99,7 @@ struct blkif_request {
        uint64_t       id;           /* private guest value, echoed in resp  */
        union {
                struct blkif_request_rw rw;
+               struct blkif_request_trim trim;
        } u;
 };
 
@@ -109,6 +128,8 @@ DEFINE_RING_TYPES(blkif, struct blkif_request, struct 
blkif_response);
 #define VDISK_CDROM        0x1
 #define VDISK_REMOVABLE    0x2
 #define VDISK_READONLY     0x4
+#define VDISK_FILE_BACKEND 0x8
+#define VDISK_PHY_BACKEND  0x10
 
 /* Xen-defined major numbers for virtual disks, they look strangely
  * familiar */
-- 
1.7.6


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