[PATCH v7 2/8] file-posix: introduce get_sysfs_str_val for device zoned model

[Sam Li]

Use sysfs attribute files to get the string value of device
zoned model. Then get_sysfs_zoned_model can convert it to
BlockZoneModel type in QEMU.

Signed-off-by: Sam Li <faithilikerun@gmail.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
---
 block/file-posix.c               | 93 ++++++++++++++++++--------------
 include/block/block_int-common.h |  3 ++
 2 files changed, 55 insertions(+), 41 deletions(-)

diff --git a/block/file-posix.c b/block/file-posix.c
index 48cd096624..c07ac4c697 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -1210,66 +1210,71 @@ static int hdev_get_max_hw_transfer(int fd, struct stat 
*st)
 #endif
 }
 
-static int hdev_get_max_segments(int fd, struct stat *st)
-{
+/*
+ * Convert the zoned attribute file in sysfs to internal value.
+ */
+static int get_sysfs_str_val(struct stat *st, const char *attribute,
+                             char **val) {
 #ifdef CONFIG_LINUX
-    char buf[32];
-    const char *end;
-    char *sysfspath = NULL;
+    g_autofree char *sysfspath = NULL;
     int ret;
-    int sysfd = -1;
-    long max_segments;
-
-    if (S_ISCHR(st->st_mode)) {
-        if (ioctl(fd, SG_GET_SG_TABLESIZE, &ret) == 0) {
-            return ret;
-        }
-        return -ENOTSUP;
-    }
+    size_t len;
 
     if (!S_ISBLK(st->st_mode)) {
         return -ENOTSUP;
     }
 
-    sysfspath = g_strdup_printf("/sys/dev/block/%u:%u/queue/max_segments",
-                                major(st->st_rdev), minor(st->st_rdev));
-    sysfd = open(sysfspath, O_RDONLY);
-    if (sysfd == -1) {
-        ret = -errno;
-        goto out;
+    sysfspath = g_strdup_printf("/sys/dev/block/%u:%u/queue/%s",
+                                major(st->st_rdev), minor(st->st_rdev),
+                                attribute);
+    ret = g_file_get_contents(sysfspath, val, &len, NULL);
+    if (ret == -1) {
+        return -ENOENT;
     }
-    do {
-        ret = read(sysfd, buf, sizeof(buf) - 1);
-    } while (ret == -1 && errno == EINTR);
+    return ret;
+#else
+    return -ENOTSUP;
+#endif
+}
+
+static int get_sysfs_zoned_model(struct stat *st, BlockZoneModel *zoned) {
+    g_autofree char *val = NULL;
+    int ret;
+
+    ret = get_sysfs_str_val(st, "zoned", &val);
     if (ret < 0) {
-        ret = -errno;
-        goto out;
-    } else if (ret == 0) {
-        ret = -EIO;
-        goto out;
+        return ret;
     }
-    buf[ret] = 0;
-    /* The file is ended with '\n', pass 'end' to accept that. */
-    ret = qemu_strtol(buf, &end, 10, &max_segments);
-    if (ret == 0 && end && *end == '\n') {
-        ret = max_segments;
+
+    if (strcmp(val, "host-managed") == 0) {
+        *zoned = BLK_Z_HM;
+    } else if (strcmp(val, "host-aware") == 0) {
+        *zoned = BLK_Z_HA;
+    } else if (strcmp(val, "none") == 0) {
+        *zoned = BLK_Z_NONE;
+    } else {
+        return -ENOTSUP;
     }
+    return 0;
+}
 
-out:
-    if (sysfd != -1) {
-        close(sysfd);
+static int hdev_get_max_segments(int fd, struct stat *st) {
+    int ret;
+    if (S_ISCHR(st->st_mode)) {
+        if (ioctl(fd, SG_GET_SG_TABLESIZE, &ret) == 0) {
+            return ret;
+        }
+        return -ENOTSUP;
     }
-    g_free(sysfspath);
-    return ret;
-#else
-    return -ENOTSUP;
-#endif
+    return get_sysfs_long_val(st, "max_segments");
 }
 
 static void raw_refresh_limits(BlockDriverState *bs, Error **errp)
 {
     BDRVRawState *s = bs->opaque;
     struct stat st;
+    int ret;
+    BlockZoneModel zoned;
 
     s->needs_alignment = raw_needs_alignment(bs);
     raw_probe_alignment(bs, s->fd, errp);
@@ -1307,6 +1312,12 @@ static void raw_refresh_limits(BlockDriverState *bs, 
Error **errp)
             bs->bl.max_hw_iov = ret;
         }
     }
+
+    ret = get_sysfs_zoned_model(s->fd, &st, &zoned);
+    if (ret < 0) {
+        zoned = BLK_Z_NONE;
+    }
+    bs->bl.zoned = zoned;
 }
 
 static int check_for_dasd(int fd)
diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h
index 8947abab76..7f7863cc9e 100644
--- a/include/block/block_int-common.h
+++ b/include/block/block_int-common.h
@@ -825,6 +825,9 @@ typedef struct BlockLimits {
 
     /* maximum number of iovec elements */
     int max_iov;
+
+    /* device zone model */
+    BlockZoneModel zoned;
 } BlockLimits;
 
 typedef struct BdrvOpBlocker BdrvOpBlocker;
-- 
2.37.1