dm: storage: change DISCARD to synchronous mode

conghuic23 · wenlingz · commit ca925f0dd4ba · 2019-01-23T12:56:47.000+08:00
For virtio-blk, when the backend is a regular file, the discard and is implemented by fallocate(), but this function will not wait for the discard command handled by disk. So, add fdatasync to make sure the DISCARD is executed synchronously. Tracked-On: #2395 Signed-off-by: Conghui Chen <conghui.chen@intel.com> Acked-by: Wang Yu <yu1.wang@intel.com>
diff --git a/devicemodel/hw/block_if.c b/devicemodel/hw/block_if.c
@@ -313,6 +313,8 @@ blockif_process_discard(struct blockif_ctxt *bc, struct blockif_req *br)
 			 */
 			err = fallocate(bc->fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
 				arg[i][0], arg[i][1]);
+			if (!err)
+				err = fdatasync(bc->fd);
 		}
 		if (err) {
 			WPRINTF(("Failed to discard offset=%ld nbytes=%ld err code: %d\n",

Original file line number	Diff line number	Diff line change
`@@ -313,6 +313,8 @@ blockif_process_discard(struct blockif_ctxt bc, struct blockif_req br)`
`313`	`313`	`*/`
`314`	`314`	`err = fallocate(bc->fd, FALLOC_FL_PUNCH_HOLE \| FALLOC_FL_KEEP_SIZE,`
`315`	`315`	`arg[i][0], arg[i][1]);`
	`316`	`+ if (!err)`
	`317`	`+ err = fdatasync(bc->fd);`
`316`	`318`	`}`
`317`	`319`	`if (err) {`
`318`	`320`	`WPRINTF(("Failed to discard offset=%ld nbytes=%ld err code: %d\n",`