* Copyright (C) 2009 The Regents of the University of California
* Written by Michael Vrable <mvrable@cs.ucsd.edu>
*
- * TODO: Licensing
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
*/
#include <stdint.h>
/* Core filesystem: handling of regular files and caching of file data. */
/* Mark a given block dirty and make sure that data is faulted in so that it
- * can be written to. */
-void bluesky_block_touch(BlueSkyInode *inode, uint64_t i)
+ * can be written to.
+ *
+ * If preserve is set to false, this is a hint that the block is about to be
+ * entirely overwritten. In this case, a dirty block is made available but any
+ * prior contents might be lost. A value of preserve = TRUE is always safe. */
+void bluesky_block_touch(BlueSkyInode *inode, uint64_t i, gboolean preserve)
{
g_return_if_fail(i < inode->blocks->len);
BlueSkyBlock *block = &g_array_index(inode->blocks, BlueSkyBlock, i);
block->dirty = bluesky_string_new(g_malloc0(block_len), block_len);
break;
case BLUESKY_BLOCK_REF:
- // FIXME: locking on the cloudlog?
- bluesky_block_fetch(inode, block, NULL);
- bluesky_string_ref(block->ref->data);
- block->dirty = bluesky_string_dup(block->ref->data);
+ if (preserve) {
+ // FIXME: locking on the cloudlog?
+ bluesky_block_fetch(inode, block, NULL);
+ bluesky_string_ref(block->ref->data);
+ block->dirty = bluesky_string_dup(block->ref->data);
+ } else {
+ block->dirty = bluesky_string_new(g_malloc0(block_len), block_len);
+ }
break;
case BLUESKY_BLOCK_DIRTY:
block->dirty = bluesky_string_dup(block->dirty);
uint64_t blocks = (size + BLUESKY_BLOCK_SIZE - 1) / BLUESKY_BLOCK_SIZE;
+ /* Calculate number of bytes in the last block of the file */
+ int lastblock_old, lastblock_new;
+ lastblock_old = inode->size % BLUESKY_BLOCK_SIZE;
+ if (lastblock_old == 0 && inode->size > 0)
+ lastblock_old = BLUESKY_BLOCK_SIZE;
+ lastblock_new = size % BLUESKY_BLOCK_SIZE;
+ if (lastblock_new == 0 && size > 0)
+ lastblock_new = BLUESKY_BLOCK_SIZE;
+
if (blocks > inode->blocks->len) {
/* Need to add new blocks to the end of a file. New block structures
* are automatically zeroed, which initializes them to be pointers to
inode->blocks->len - 1);
if (b->type != BLUESKY_BLOCK_ZERO
- && (b->type == BLUESKY_BLOCK_REF
- || b->dirty->len < BLUESKY_BLOCK_SIZE)) {
- bluesky_block_touch(inode, inode->blocks->len - 1);
+ && lastblock_old < BLUESKY_BLOCK_SIZE) {
+ bluesky_block_touch(inode, inode->blocks->len - 1, TRUE);
gsize old_size = b->dirty->len;
+ if (lastblock_old != old_size) {
+ fprintf(stderr,
+ "Warning: last block size = %zd, expected %d\n",
+ old_size, lastblock_old);
+ }
bluesky_string_resize(b->dirty, BLUESKY_BLOCK_SIZE);
memset(&b->dirty->data[old_size], 0,
BLUESKY_BLOCK_SIZE - old_size);
BlueSkyBlock *b = &g_array_index(inode->blocks, BlueSkyBlock,
blocks - 1);
- if (b->type != BLUESKY_BLOCK_ZERO) {
- bluesky_block_touch(inode, blocks - 1);
+ gboolean need_resize = TRUE;
+ if (b->type == BLUESKY_BLOCK_ZERO)
+ need_resize = FALSE;
+ else if (size < inode->size && lastblock_new == BLUESKY_BLOCK_SIZE)
+ need_resize = FALSE;
+
+ if (need_resize) {
+ bluesky_block_touch(inode, blocks - 1, TRUE);
gsize old_size = b->dirty->len;
gsize new_size = size - (blocks - 1) * BLUESKY_BLOCK_SIZE;
if (len == 0)
return;
- // TODO: Optimization: If we are entirely overwriting a block we don't need
- // to fetch it frm storage first.
while (len > 0) {
uint64_t block_num = offset / BLUESKY_BLOCK_SIZE;
gint block_offset = offset % BLUESKY_BLOCK_SIZE;
gint bytes = MIN(BLUESKY_BLOCK_SIZE - block_offset, len);
- bluesky_block_touch(inode, block_num);
+ gboolean preserve = TRUE;
+ gsize block_size = BLUESKY_BLOCK_SIZE;
+ if (block_num == inode->blocks->len - 1) {
+ block_size = inode->size - block_num * BLUESKY_BLOCK_SIZE;
+ }
+ if (block_offset == 0 && bytes == block_size) {
+ preserve = FALSE;
+ }
+ bluesky_block_touch(inode, block_num, preserve);
BlueSkyBlock *b = &g_array_index(inode->blocks, BlueSkyBlock,
block_num);
memcpy(&b->dirty->data[block_offset], data, bytes);
projects / bluesky.git / blobdiff