[PATCH 02/12] btrfs-progs: utils: Introduce queue_param

[Naohiro Aota]

Introduce the queue_param function to get a device request queue
parameter and this function to test if the device is an SSD in
is_ssd().

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

diff --git a/mkfs/main.c b/mkfs/main.c
index b442e6e40c37..93c0b71c864e 100644
--- a/mkfs/main.c
+++ b/mkfs/main.c
@@ -404,49 +404,13 @@ 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';
 }
 
diff --git a/utils.c b/utils.c
index c6cdc8f01dc1..7d5a1f3b7f8d 100644
--- a/utils.c
+++ b/utils.c
@@ -65,6 +65,52 @@ static unsigned short rand_seed[3];
 
 struct btrfs_config bconf;
 
+/*
+ * 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;
+}
+
 /*
  * Discard the given range in one go
  */
diff --git a/utils.h b/utils.h
index 7c5eb798557d..47321f62c8e0 100644
--- a/utils.h
+++ b/utils.h
@@ -121,6 +121,7 @@ int get_label(const char *btrfs_dev, char *label);
 int set_label(const char *btrfs_dev, const char *label);
 
 char *__strncpy_null(char *dest, const char *src, size_t n);
+int queue_param(const char *file, const char *param, char *buf, size_t len);
 int is_block_device(const char *file);
 int is_mount_point(const char *file);
 int is_path_exist(const char *file);
-- 
2.21.0