[PATCH v3 01/15] btrfs-progs: utils: Introduce queue_param helper function

[Naohiro Aota <naohiro.aota@wdc.com>]

Introduce the queue_param helper function to get a device request queue
parameter.  This helper will be used later to query information of a zoned
device.

Furthermore, rewrite is_ssd() using the helper function.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
[Naohiro] fixed error return value
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
---
 common/device-utils.c | 46 +++++++++++++++++++++++++++++++++++++++++++
 common/device-utils.h |  1 +
 mkfs/main.c           | 40 ++-----------------------------------
 3 files changed, 49 insertions(+), 38 deletions(-)

diff --git a/common/device-utils.c b/common/device-utils.c
index b03d62faaf21..7fa9386f4677 100644
--- a/common/device-utils.c
+++ b/common/device-utils.c
@@ -252,3 +252,49 @@ u64 get_partition_size(const char *dev)
 	return result;
 }
 
+/*
+ * Get a device request queue parameter.
+ */
+int queue_param(const char *file, const char *param, char *buf, size_t len)
+{
+	blkid_probe probe;
+	char wholedisk[PATH_MAX];
+	char sysfs_path[PATH_MAX];
+	dev_t devno;
+	int fd;
+	int ret;
+
+	probe = blkid_new_probe_from_filename(file);
+	if (!probe)
+		return 0;
+
+	/* Device number of this disk (possibly a partition) */
+	devno = blkid_probe_get_devno(probe);
+	if (!devno) {
+		blkid_free_probe(probe);
+		return 0;
+	}
+
+	/* Get whole disk name (not full path) for this devno */
+	ret = blkid_devno_to_wholedisk(devno,
+			wholedisk, sizeof(wholedisk), NULL);
+	if (ret) {
+		blkid_free_probe(probe);
+		return 0;
+	}
+
+	snprintf(sysfs_path, PATH_MAX, "/sys/block/%s/queue/%s",
+		 wholedisk, param);
+
+	blkid_free_probe(probe);
+
+	fd = open(sysfs_path, O_RDONLY);
+	if (fd < 0)
+		return 0;
+
+	len = read(fd, buf, len);
+	close(fd);
+
+	return len;
+}
+
diff --git a/common/device-utils.h b/common/device-utils.h
index 70d19cae3e50..d1799323d002 100644
--- a/common/device-utils.h
+++ b/common/device-utils.h
@@ -29,5 +29,6 @@ u64 disk_size(const char *path);
 u64 btrfs_device_size(int fd, struct stat *st);
 int btrfs_prepare_device(int fd, const char *file, u64 *block_count_ret,
 		u64 max_block_count, unsigned opflags);
+int queue_param(const char *file, const char *param, char *buf, size_t len);
 
 #endif
diff --git a/mkfs/main.c b/mkfs/main.c
index 971cb39534fd..948c84be5f39 100644
--- a/mkfs/main.c
+++ b/mkfs/main.c
@@ -426,49 +426,13 @@ static int zero_output_file(int out_fd, u64 size)
 
 static int is_ssd(const char *file)
 {
-	blkid_probe probe;
-	char wholedisk[PATH_MAX];
-	char sysfs_path[PATH_MAX];
-	dev_t devno;
-	int fd;
 	char rotational;
 	int ret;
 
-	probe = blkid_new_probe_from_filename(file);
-	if (!probe)
+	ret = queue_param(file, "rotational", &rotational, 1);
+	if (ret < 1)
 		return 0;
 
-	/* Device number of this disk (possibly a partition) */
-	devno = blkid_probe_get_devno(probe);
-	if (!devno) {
-		blkid_free_probe(probe);
-		return 0;
-	}
-
-	/* Get whole disk name (not full path) for this devno */
-	ret = blkid_devno_to_wholedisk(devno,
-			wholedisk, sizeof(wholedisk), NULL);
-	if (ret) {
-		blkid_free_probe(probe);
-		return 0;
-	}
-
-	snprintf(sysfs_path, PATH_MAX, "/sys/block/%s/queue/rotational",
-		 wholedisk);
-
-	blkid_free_probe(probe);
-
-	fd = open(sysfs_path, O_RDONLY);
-	if (fd < 0) {
-		return 0;
-	}
-
-	if (read(fd, &rotational, 1) < 1) {
-		close(fd);
-		return 0;
-	}
-	close(fd);
-
 	return rotational == '0';
 }
 
-- 
2.23.0