From: Owen Smith <owen.smith@xxxxxxxxxx>
Patches xen.git, on branch xen/next-2.6.32
Trim operation is a request for the underlying block device to mark
extents to be erased. Add the operation code and ring data structure
to the interface, and a stub response to the blkback device.
Trim operations are passed with sector_number as the sector index to
begin trim operations at and nr_sectors as the number of sectors to
be trimmed. The specified sectors should be trimmed if the underlying
block device supports trim operations, or a BLKIF_RSP_EOPNOTSUPP should
be returned. More information about trim operations at;
http://t13.org/Documents/UploadedDocuments/docs2008/
e07154r6-Data_Set_Management_Proposal_for_ATA-ACS2.doc
Signed-off-by: Owen Smith <owen.smith@xxxxxxxxxx>
---
drivers/xen/blkback/blkback.c | 7 +++++++
include/xen/interface/io/blkif.h | 17 +++++++++++++++++
2 files changed, 24 insertions(+), 0 deletions(-)
diff --git a/drivers/xen/blkback/blkback.c b/drivers/xen/blkback/blkback.c
index b45b21f..03cb8f6 100644
--- a/drivers/xen/blkback/blkback.c
+++ b/drivers/xen/blkback/blkback.c
@@ -367,6 +367,13 @@ static int do_block_io_op(blkif_t *blkif)
blkif->st_wr_req++;
dispatch_rw_block_io(blkif, &req, pending_req);
break;
+ case BLKIF_OP_TRIM:
+ /* respond with BLKIF_RSP_EOPNOTSUPP to reduce logging
+ * from default case */
+ make_response(blkif, req.id, req.operation,
+ BLKIF_RSP_EOPNOTSUPP);
+ free_req(pending_req);
+ break;
default:
/* A good sign something is wrong: sleep for a while to
* avoid excessive CPU consumption by a bad guest. */
diff --git a/include/xen/interface/io/blkif.h b/include/xen/interface/io/blkif.h
index 61e523a..2ae8840 100644
--- a/include/xen/interface/io/blkif.h
+++ b/include/xen/interface/io/blkif.h
@@ -43,6 +43,17 @@ typedef uint64_t blkif_sector_t;
* create the "feature-barrier" node!
*/
#define BLKIF_OP_WRITE_BARRIER 2
+/*
+ * 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.
@@ -61,6 +72,11 @@ 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 */
@@ -68,6 +84,7 @@ struct blkif_request {
uint64_t id; /* private guest value, echoed in resp */
union {
struct blkif_request_rw rw;
+ struct blkif_request_trim trim;
} u;
};
--
1.5.6.5
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