Changeset d5a720cf in mainline

Timestamp:

2008-11-02T19:28:38Z (16 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

a6d97fb9

Parents:

6132b59

Message:

Implementation of block_put().

File:

• uspace/lib/libblock/libblock.c (modified) (2 diffs)

uspace/lib/libblock/libblock.c

@@ -275 +275 @@
 
         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;
 }
@@ -437 +378 @@
 }
 
+/** 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;
 }