flashbench: implement erase operation using BLKDISCARD

Erasing blocks has a huge impact on timing, we need to test this.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

3 files changed, 55 insertions, 21 deletions

diff --git a/dev.c b/dev.c
index 4cb4a3a..319003a 100644
--- a/dev.c
+++ b/dev.c
@@ -4,6 +4,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/time.h>
+#include <sys/ioctl.h>
 #include <unistd.h>
 #include <stdlib.h>
 #include <stdio.h>
@@ -17,6 +18,8 @@
 #include <getopt.h>
 #include <stdbool.h>
 
+#include <linux/fs.h>
+
 #include "dev.h"
 
 #define MAX_BUFSIZE (64 * 1024 * 1024)
@@ -83,6 +86,25 @@ long long time_write(struct device *dev, off_t pos, size_t size, enum writebuf w
 	return get_ns() - now;
 }
 
+long long time_erase(struct device *dev, off_t pos, size_t size)
+{
+	long long now = get_ns();
+	ssize_t ret;
+	unsigned long long args[2] = { size, pos % dev->size };
+
+	if (size > MAX_BUFSIZE)
+		return -ENOMEM;
+
+	ret = ioctl(dev->fd, BLKDISCARD, &args);
+
+	if (ret) {
+		perror("time_erase");
+		return 0;
+	}
+
+	return get_ns() - now;
+}
+
 static void set_rtprio(void)
 {
 	int ret;
@@ -97,7 +119,7 @@ static void set_rtprio(void)
 
 int setup_dev(struct device *dev, const char *filename)
 {
-	int i, err;
+	int err;
 	void *p;
 	set_rtprio();
 
diff --git a/dev.h b/dev.h
index 865a7c8..9d30197 100644
--- a/dev.h
+++ b/dev.h
@@ -22,4 +22,6 @@ long long time_write(struct device *dev, off_t pos, size_t size, enum writebuf w
 
 long long time_read(struct device *dev, off_t pos, size_t size);
 
+long long time_erase(struct device *dev, off_t pos, size_t size);
+
 #endif /* FLASHBENCH_DEV_H */
diff --git a/vm.c b/vm.c
index e51e5e3..e65770c 100644
--- a/vm.c
+++ b/vm.c
@@ -172,24 +172,34 @@ static struct operation *do_read(struct operation *op, struct device *dev,
 	return op+1;
 }
 
-static struct operation *do_write(struct operation *op, struct device *dev,
+static struct operation *do_write_zero(struct operation *op, struct device *dev,
 		 off_t off, off_t max, size_t len)
 {
-	enum writebuf writebuf;
-	switch (op->code) {
-	case O_WRITE_ZERO:
-		writebuf = WBUF_ZERO;
-		break;
-	case O_WRITE_ONE:
-		writebuf = WBUF_ONE;
-		break;
-	case O_WRITE_RAND:
-		writebuf = WBUF_RAND;
-		break;
-	default:
-		return NULL;
-	}
-	op->result.l = time_write(dev, off, len, writebuf);
+	op->result.l = time_write(dev, off, len, WBUF_ZERO);
+	op->r_type = R_NS;
+	return op+1;
+}
+
+static struct operation *do_write_one(struct operation *op, struct device *dev,
+		 off_t off, off_t max, size_t len)
+{
+	op->result.l = time_write(dev, off, len, WBUF_ONE);
+	op->r_type = R_NS;
+	return op+1;
+}
+
+static struct operation *do_write_rand(struct operation *op, struct device *dev,
+		 off_t off, off_t max, size_t len)
+{
+	op->result.l = time_write(dev, off, len, WBUF_RAND);
+	op->r_type = R_NS;
+	return op+1;
+}
+
+static struct operation *do_erase(struct operation *op, struct device *dev,
+		 off_t off, off_t max, size_t len)
+{
+	op->result.l = time_erase(dev, off, len);
 	op->r_type = R_NS;
 	return op+1;
 }
@@ -688,10 +698,10 @@ static struct operation *drop(struct operation *op, struct device *dev,
 static struct syntax syntax[] = {
 	{ O_END,	"END",		nop,		},
 	{ O_READ,	"READ",		do_read,	},
-	{ O_WRITE_ZERO,	"WRITE_ZERO",	do_write,	},
-	{ O_WRITE_ONE,	"WRITE_ONE",	do_write,	},
-	{ O_WRITE_RAND,	"WRITE_RAND",	do_write,	},
-	{ O_ERASE,	"ERASE",	nop,		},
+	{ O_WRITE_ZERO,	"WRITE_ZERO",	do_write_zero,	},
+	{ O_WRITE_ONE,	"WRITE_ONE",	do_write_one,	},
+	{ O_WRITE_RAND,	"WRITE_RAND",	do_write_rand,	},
+	{ O_ERASE,	"ERASE",	do_erase,	},
 	{ O_LENGTH,	"LENGTH",	length_or_offs	},
 	{ O_OFFSET,	"OFFSET",	length_or_offs,	},