[Xen-devel] [PATCH V3 1/3] xen-blkback: add BLKIF_OP_TRIM and backend types

[Li Dongyang <lidongyang@xxxxxxxxxx>]

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

Signed-off-by: Owen Smith <owen.smith@xxxxxxxxxx>
Signed-off-by: Li Dongyang <lidongyang@xxxxxxxxxx>
---
 drivers/block/xen-blkback/common.h |   10 +++++++++-
 include/xen/interface/io/blkif.h   |   19 +++++++++++++++++++
 2 files changed, 28 insertions(+), 1 deletions(-)

diff --git a/drivers/block/xen-blkback/common.h 
b/drivers/block/xen-blkback/common.h
index 9e40b28..146d325 100644
--- a/drivers/block/xen-blkback/common.h
+++ b/drivers/block/xen-blkback/common.h
@@ -113,6 +113,11 @@ enum blkif_protocol {
        BLKIF_PROTOCOL_X86_64 = 3,
 };
 
+enum blkif_backend_type {
+       BLKIF_BACKEND_PHY  = 1,
+       BLKIF_BACKEND_FILE = 2,
+};
+
 struct xen_vbd {
        /* What the domain refers to this vbd as. */
        blkif_vdev_t            handle;
@@ -138,6 +143,7 @@ struct xen_blkif {
        unsigned int            irq;
        /* Comms information. */
        enum blkif_protocol     blk_protocol;
+       enum blkif_backend_type blk_backend_type;
        union blkif_back_rings  blk_rings;
        struct vm_struct        *blk_ring_area;
        /* The VBD attached to this interface. */
@@ -159,8 +165,10 @@ struct xen_blkif {
        int                     st_wr_req;
        int                     st_oo_req;
        int                     st_f_req;
+       int                     st_tr_req;
        int                     st_rd_sect;
        int                     st_wr_sect;
+       int                     st_tr_sect;
 
        wait_queue_head_t       waiting_to_free;
 
@@ -182,7 +190,7 @@ struct xen_blkif {
 
 struct phys_req {
        unsigned short          dev;
-       unsigned short          nr_sects;
+       blkif_sector_t          nr_sects;
        struct block_device     *bdev;
        blkif_sector_t          sector_number;
 };
diff --git a/include/xen/interface/io/blkif.h b/include/xen/interface/io/blkif.h
index 3d5d6db..43762dd 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 trim
+ * 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;
 };
 
-- 
1.7.6


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