kernel: devfs: Add callback to request block size

Add bsize() callback within the bdevsw structure. This returns the
number of blocks a block device supports at maximum. This result is *not*
in bytes.

Signed-off-by: Ian Moffett <ian@osmora.org>

3 files changed, 20 insertions, 1 deletions

diff --git a/sys/fs/devfs.c b/sys/fs/devfs.c
index 15a2864..1dfc10d 100644
--- a/sys/fs/devfs.c
+++ b/sys/fs/devfs.c
@@ -137,6 +137,8 @@ devfs_getattr(struct vop_getattr_args *args)
     struct vnode *vp;
     struct vattr *attr;
     struct devfs_node *dnp;
+    struct bdevsw *bdev;
+    size_t size = 0;
 
     vp = args->vp;
     if ((dnp = vp->data) == NULL) {
@@ -146,6 +148,13 @@ devfs_getattr(struct vop_getattr_args *args)
         return -EIO;
     }
 
+    if (dnp->is_block) {
+        bdev = dev_get(dnp->major, dnp->dev);
+        if (bdev->bsize != NULL) {
+            size = bdev->bsize(dnp->dev);
+        }
+    }
+
     /*
      * Set stat attributes from device node structure
      * found within vnode data.
@@ -154,7 +163,7 @@ devfs_getattr(struct vop_getattr_args *args)
      *      size is hardwired to 0.
      */
     attr->mode = dnp->mode;
-    attr->size = 0;
+    attr->size = size;
     return 0;
 }
 
diff --git a/sys/include/sys/device.h b/sys/include/sys/device.h
index f5f92ad..fcafdab 100644
--- a/sys/include/sys/device.h
+++ b/sys/include/sys/device.h
@@ -42,6 +42,7 @@ typedef uint8_t devmajor_t;
 /* Device operation typedefs */
 typedef int(*dev_read_t)(dev_t, struct sio_txn *, int);
 typedef int(*dev_write_t)(dev_t, struct sio_txn *, int);
+typedef int(*dev_bsize_t)(dev_t);
 
 struct cdevsw {
     int(*read)(dev_t dev, struct sio_txn *sio, int flags);
@@ -51,6 +52,7 @@ struct cdevsw {
 struct bdevsw {
     int(*read)(dev_t dev, struct sio_txn *sio, int flags);
     int(*write)(dev_t dev, struct sio_txn *sio, int flags);
+    int(*bsize)(dev_t dev);
 };
 
 void *dev_get(devmajor_t major, dev_t dev);
@@ -61,10 +63,12 @@ int dev_register(devmajor_t major, dev_t dev, void *devsw);
 
 int dev_noread(void);
 int dev_nowrite(void);
+int dev_nobsize(void);
 
 /* Device operation stubs */
 #define noread ((dev_read_t)dev_noread)
 #define nowrite ((dev_write_t)dev_nowrite)
+#define nobsize ((dev_bsize_t)dev_nobsize)
 
 #endif  /* _KERNEL */
 #endif  /* !_SYS_DEVICE_H_ */
diff --git a/sys/kern/kern_stub.c b/sys/kern/kern_stub.c
index 8603fd5..1a5fb0e 100644
--- a/sys/kern/kern_stub.c
+++ b/sys/kern/kern_stub.c
@@ -75,3 +75,9 @@ dev_nowrite(void)
 {
     return -ENOTSUP;
 }
+
+int
+dev_nobsize(void)
+{
+    return -ENOTSUP;
+}