[RFC v5 03/11] file-posix: introduce get_sysfs_long_val for the long sysfs attribute

[Sam Li]

Use sysfs attribute files to get the long value of zoned device
information.

Signed-off-by: Sam Li <faithilikerun@gmail.com>
---
 block/file-posix.c | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/block/file-posix.c b/block/file-posix.c
index 48cd096624..bcf898f0cb 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -1210,15 +1210,19 @@ static int hdev_get_max_hw_transfer(int fd, struct stat 
*st)
 #endif
 }
 
-static int hdev_get_max_segments(int fd, struct stat *st)
-{
+/*
+ * Get zoned device information (chunk_sectors, zoned_append_max_bytes,
+ * max_open_zones, max_active_zones) through sysfs attribute files.
+ */
+static long get_sysfs_long_val(int fd, struct stat *st,
+                               const char *attribute) {
 #ifdef CONFIG_LINUX
     char buf[32];
     const char *end;
     char *sysfspath = NULL;
     int ret;
     int sysfd = -1;
-    long max_segments;
+    long val;
 
     if (S_ISCHR(st->st_mode)) {
         if (ioctl(fd, SG_GET_SG_TABLESIZE, &ret) == 0) {
@@ -1231,8 +1235,9 @@ static int hdev_get_max_segments(int fd, struct stat *st)
         return -ENOTSUP;
     }
 
-    sysfspath = g_strdup_printf("/sys/dev/block/%u:%u/queue/max_segments",
-                                major(st->st_rdev), minor(st->st_rdev));
+    sysfspath = g_strdup_printf("/sys/dev/block/%u:%u/queue/%s",
+                                major(st->st_rdev), minor(st->st_rdev),
+                                attribute);
     sysfd = open(sysfspath, O_RDONLY);
     if (sysfd == -1) {
         ret = -errno;
@@ -1250,9 +1255,9 @@ static int hdev_get_max_segments(int fd, struct stat *st)
     }
     buf[ret] = 0;
     /* The file is ended with '\n', pass 'end' to accept that. */
-    ret = qemu_strtol(buf, &end, 10, &max_segments);
+    ret = qemu_strtol(buf, &end, 10, &val);
     if (ret == 0 && end && *end == '\n') {
-        ret = max_segments;
+        ret = val;
     }
 
 out:
@@ -1266,6 +1271,10 @@ out:
 #endif
 }
 
+static int hdev_get_max_segments(int fd, struct stat *st) {
+    return get_sysfs_long_val(fd, st, "max_segments");
+}
+
 static void raw_refresh_limits(BlockDriverState *bs, Error **errp)
 {
     BDRVRawState *s = bs->opaque;
-- 
2.37.1