Changeset 1d8cdb1 in mainline for uspace/lib/libblock/libblock.c

Timestamp:

2008-11-18T20:28:17Z (16 years ago)

Author:

Jakub Jermar <jakub@…>

Branches:

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

Children:

18c485a

Parents:

26fa0f9f

Message:

Avoid unnecessary block reads in block_get().

File:

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

uspace/lib/libblock/libblock.c

@@ -297 +297 @@
  * @param dev_handle            Device handle of the block device.
  * @param boff                  Block offset.
+ * @param flags                 If BLOCK_FLAGS_NOREAD is specified, block_get()
+ *                              will not read the contents of the block from the
+ *                              device.
  *
  * @return                      Block structure.
  */
-block_t *block_get(dev_handle_t dev_handle, bn_t boff)
+block_t *block_get(dev_handle_t dev_handle, bn_t boff, int flags)
 {
         devcon_t *devcon;
@@ -386 +389 @@
                         abort();        /* TODO: block_write() */
                 }
-                /*
-                 * The block contains old or no data. We need to read the new
-                 * contents from the device.
-                 */
-                rc = block_read(dev_handle, &bufpos, &buflen, &pos, b->data,
-                    cache->block_size, cache->block_size);
-                assert(rc == EOK);
+                if (!(flags & BLOCK_FLAGS_NOREAD)) {
+                        /*
+                         * The block contains old or no data. We need to read
+                         * the new contents from the device.
+                         */
+                        rc = block_read(dev_handle, &bufpos, &buflen, &pos,
+                            b->data, cache->block_size, cache->block_size);
+                        assert(rc == EOK);
+                }
 
                 futex_up(&b->lock);