3 files changed, 82 insertions, 15 deletions

diff --git a/sys/include/sys/disk.h b/sys/include/sys/disk.h
index 0570fe2..4ad068b 100644
--- a/sys/include/sys/disk.h
+++ b/sys/include/sys/disk.h
@@ -41,6 +41,8 @@
 #include <dev/dcdr/cache.h>
 #endif  /* _KERNEL */
 
+#define DISK_NAME_MAX 64
+
 /*
  * V_BSIZE is the virtual block size in bytes used
  * by the disk framework. The virtual block size is a
@@ -74,8 +76,9 @@ _Static_assert((V_BSIZE & 1) == 0, "V_BSIZE must be a power of two");
 #define DISK_PARAM_COOKIE  0xD1531001
 
 /* Valid disk operations */
-#define DISK_IO_READ    0x00
-#define DISK_IO_WRITE   0x01
+#define DISK_IO_READ    0x00    /* Read data from the disk */
+#define DISK_IO_WRITE   0x01    /* Write data to disk */
+#define DISK_IO_QUERY   0x02    /* Query disk information */
 
 /*
  * A disk identifier is a zero-based index into
@@ -95,18 +98,30 @@ typedef off_t blkoff_t;
 typedef uint8_t diskop_t;
 
 /*
+ * Describes basic disk information
+ *
+ * @block_size: Hardware block size
+ * @vblock_size: Virtual block size
+ * @n_block: Number of blocks total
+ */
+struct disk_info {
+    uint32_t block_size;
+    uint32_t vblock_size;
+    size_t n_block;
+};
+
+/*
  * The disk metadata structure contains information
  * describing the disk. It is used for Hyra's pbuf
  * (persistent buffers / sls) support. This structure
  * is to be stored at the very last sector of the drive.
  *
- * @root_blk: Disk offset to root block
- * @n_ublk: Number of usable user blocks
+ * @canary: Boot canary to verify persistent instance
+ * @info: Disk attributes
  */
-struct disk_meta {
-    char magic[6];
-    blkoff_t root_blk;
-    size_t n_ublk;
+struct disk_root {
+    uint32_t canary;
+    struct disk_info info;
 };
 
 /*
@@ -141,7 +156,7 @@ struct disk_param {
  * @res: Pointer to params to be initialized
  */
 __always_inline static inline void
-disk_param_init(uint8_t *buf, blkoff_t blk, size_t size, struct disk_param *res)
+disk_param_init(void *buf, blkoff_t blk, size_t size, struct disk_param *res)
 {
     if (res != NULL) {
         res->buf = buf;
@@ -156,10 +171,13 @@ disk_param_init(uint8_t *buf, blkoff_t blk, size_t size, struct disk_param *res)
  */
 #if !defined(_KERNEL)
 ssize_t __disk_io(diskid_t id, diskop_t op, const struct disk_param *param);
-ssize_t disk_write(diskid_t id, blkoff_t off, const void *buf, size_t len);
-ssize_t disk_read(diskid_t id, blkoff_t off, void *buf, size_t len);
 #endif  /* !_KERNEL */
 
+/* Common disk operations */
+int disk_query(diskid_t id, struct disk_info *res);
+ssize_t disk_read(diskid_t id, blkoff_t blk, void *buf, size_t len);
+ssize_t disk_write(diskid_t id, blkoff_t blk, const void *buf, size_t len);
+
 #if defined(_KERNEL)
 /*
  * Represents a block storage device
@@ -173,7 +191,7 @@ ssize_t disk_read(diskid_t id, blkoff_t off, void *buf, size_t len);
  * @link: TAILQ link
  */
 struct disk {
-    char name[NAME_MAX];
+    char name[DISK_NAME_MAX];
     uint32_t cookie;
     uint16_t bsize;
     dev_t dev;
@@ -185,9 +203,6 @@ struct disk {
 void *disk_buf_alloc(diskid_t id, size_t len);
 void disk_buf_free(void *p);
 
-ssize_t disk_read(diskid_t id, blkoff_t blk, void *buf, size_t len);
-ssize_t disk_write(diskid_t id, blkoff_t blk, const void *buf, size_t len);
-
 int disk_add(const char *name, dev_t dev, const struct bdevsw *bdev, int flags);
 int disk_get_id(diskid_t id, struct disk **res);
 
diff --git a/sys/kern/disk_engine.c b/sys/kern/disk_engine.c
index a49c15f..1061165 100644
--- a/sys/kern/disk_engine.c
+++ b/sys/kern/disk_engine.c
@@ -172,6 +172,18 @@ disk_mux_io(diskid_t id, diskop_t opcode, struct disk_param *u_param)
             param.size
         );
         break;
+    case DISK_IO_QUERY:
+        retval = disk_query(
+            id,
+            param.buf
+        );
+
+        /* Write back info to user program */
+        error = copyout(param.buf, param.u_buf, param.size);
+        if (error < 0) {
+            retval = error;
+        }
+        break;
     }
 
     disk_param_free(&param);
diff --git a/sys/kern/kern_disk.c b/sys/kern/kern_disk.c
index 5c09c81..a3fa05e 100644
--- a/sys/kern/kern_disk.c
+++ b/sys/kern/kern_disk.c
@@ -433,3 +433,43 @@ disk_write(diskid_t id, blkoff_t blk, const void *buf, size_t len)
     disk_buf_free(tmp);
     return retval;
 }
+
+/*
+ * Attempt to request attributes from a specific
+ * device.
+ *
+ * @id: ID of disk to query
+ * @res: Resulting information goes here
+ *
+ * This function returns zero on success, otherwise
+ * a less than zero value is returned.
+ */
+int
+disk_query(diskid_t id, struct disk_info *res)
+{
+    const struct bdevsw *bdev;
+    struct disk *dp;
+    int error;
+
+    if (res == NULL) {
+        return -EINVAL;
+    }
+
+    /* Attempt to grab the disk */
+    error = disk_get_id(id, &dp);
+    if (error < 0) {
+        pr_error("disk_query: bad disk ID %d\n", id);
+        return error;
+    }
+
+    bdev = dp->bdev;
+    if (__unlikely(bdev == NULL)) {
+        pr_error("disk_query: no bdev for disk %d\n", id);
+        return -EIO;
+    }
+
+    res->block_size = dp->bsize;
+    res->vblock_size = V_BSIZE;
+    res->n_block = bdev->bsize(dp->dev);
+    return 0;
+}