WebSVN – HelenOS – Diff – //trunk/uspace/lib/libblock/libblock.c

     devcon->cache = cache;
     return EOK;
+}
-/** Read data from a block device.
- *
- * @param dev_handle    Device handle of the block device.
- * @param bufpos    Pointer to the first unread valid offset within the
- *          communication buffer.
- * @param buflen    Pointer to the number of unread bytes that are ready in
- *          the communication buffer.
- * @param pos       Device position to be read.
- * @param dst       Destination buffer.
- * @param size      Size of the destination buffer.
- * @param block_size    Block size to be used for the transfer.
- *
- * @return      EOK on success or a negative return code on failure.
- */
-int
-block_read(int dev_handle, off_t *bufpos, size_t *buflen, off_t *pos, void *dst,
-    size_t size, size_t block_size)
-{
-    off_t offset = 0;
-    size_t left = size;
-    devcon_t *devcon = devcon_search(dev_handle);
-    assert(devcon);
-    while (left > 0) {
-        size_t rd;
-        if (*bufpos + left < *buflen)
-            rd = left;
-        else
-            rd = *buflen - *bufpos;
-        if (rd > 0) {
-            /*
-             * Copy the contents of the communication buffer to the
-             * destination buffer.
-             */
-            memcpy(dst + offset, devcon->com_area + *bufpos, rd);
-            offset += rd;
-            *bufpos += rd;
-            *pos += rd;
-            left -= rd;
-        }
-        if (*bufpos == *buflen) {
-            /* Refill the communication buffer with a new block. */
-            ipcarg_t retval;
-            int rc = async_req_2_1(devcon->dev_phone, RD_READ_BLOCK,
-                *pos / block_size, block_size, &retval);
-            if ((rc != EOK) || (retval != EOK))
-                return (rc != EOK ? rc : retval);
-            *bufpos = 0;
-            *buflen = block_size;
-        }
-    }
-    return EOK;
-}
 static bool cache_can_grow(cache_t *cache)
+{
     return true;
+}
     futex_up(&cache->lock);
     return b;
+}
+/** Release a reference to a block.
+ *
+ * If the last reference is dropped, the block is put on the free list.  If the
+ * last reference is dropped and the block is dirty, it is first synced with the
+ * block device.
+ *
+ * @param block     Block of which a reference is to be released.
+ */
 void block_put(block_t *block)
+{
+    devcon_t *devcon = devcon_search(block->dev_handle);
+    cache_t *cache;
+    assert(devcon);
+    assert(devcon->cache);
+    cache = devcon->cache;
+    futex_down(&cache->lock);
+    futex_down(&block->lock);
+    if (!--block->refcnt) {
+        /*
+         * Last reference to the block was dropped, put the block on the
+         * free list.
+         */
+        list_append(&block->free_link, &cache->free_head);
+        /* Unlock the cache, but not the block. */
+        futex_up(&cache->lock);
+        if (block->dirty) {
+            /*
+             * The block is dirty and there is no one using it
+             * at the moment, write it back to the device.
+             */
+            /* TODO: block_write() */
+            block->dirty = false;
+        }
+    } else {
+        futex_up(&cache->lock);
+    }
+    futex_up(&block->lock);
+}
+/** Read data from a block device.
+ *
+ * @param dev_handle    Device handle of the block device.
+ * @param bufpos    Pointer to the first unread valid offset within the
+ *          communication buffer.
+ * @param buflen    Pointer to the number of unread bytes that are ready in
+ *          the communication buffer.
+ * @param pos       Device position to be read.
+ * @param dst       Destination buffer.
+ * @param size      Size of the destination buffer.
+ * @param block_size    Block size to be used for the transfer.
+ *
+ * @return      EOK on success or a negative return code on failure.
+ */
+int
+block_read(int dev_handle, off_t *bufpos, size_t *buflen, off_t *pos, void *dst,
+    size_t size, size_t block_size)
+{
+    off_t offset = 0;
+    size_t left = size;
+    devcon_t *devcon = devcon_search(dev_handle);
+    assert(devcon);
+    while (left > 0) {
+        size_t rd;
+        if (*bufpos + left < *buflen)
+            rd = left;
+        else
+            rd = *buflen - *bufpos;
+        if (rd > 0) {
+            /*
+             * Copy the contents of the communication buffer to the
+             * destination buffer.
+             */
+            memcpy(dst + offset, devcon->com_area + *bufpos, rd);
+            offset += rd;
+            *bufpos += rd;
+            *pos += rd;
+            left -= rd;
+        }
+        if (*bufpos == *buflen) {
+            /* Refill the communication buffer with a new block. */
+            ipcarg_t retval;
+            int rc = async_req_2_1(devcon->dev_phone, RD_READ_BLOCK,
+                *pos / block_size, block_size, &retval);
+            if ((rc != EOK) || (retval != EOK))
+                return (rc != EOK ? rc : retval);
+            *bufpos = 0;
+            *buflen = block_size;
+        }
+    }
+    return EOK;
+}
 /** @}
  */

Subversion Repositories HelenOS

(root)//trunk/uspace/lib/libblock/libblock.c – Rev 3542 → 3543