+
+/* Retrieve an inode from the filesystem. Eventually this will be a cache and
+ * so we might need to go fetch the inode from elsewhere; for now all
+ * filesystem state is stored here. */
+BlueSkyInode *bluesky_get_inode(BlueSkyFS *fs, uint64_t inum)
+{
+ BlueSkyInode *inode = NULL;
+
+ g_mutex_lock(fs->lock);
+ inode = (BlueSkyInode *)g_hash_table_lookup(fs->inodes, &inum);
+ g_mutex_unlock(fs->lock);
+
+ return inode;
+}
+
+/* Insert an inode into the filesystem inode cache. */
+void bluesky_insert_inode(BlueSkyFS *fs, BlueSkyInode *inode)
+{
+ g_mutex_lock(fs->lock);
+ g_hash_table_insert(fs->inodes, &inode->inum, inode);
+ g_mutex_unlock(fs->lock);
+}
+
+/* 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)
+{
+ g_return_if_fail(i < inode->blocks->len);
+ BlueSkyBlock *block = &g_array_index(inode->blocks, BlueSkyBlock, i);
+
+ switch (block->type) {
+ case BLUESKY_BLOCK_ZERO:
+ block->data = g_malloc0(BLUESKY_BLOCK_SIZE);
+ break;
+ case BLUESKY_BLOCK_REF:
+ /* TODO: Pull in data first */
+ block->data = g_malloc0(BLUESKY_BLOCK_SIZE);
+ break;
+ case BLUESKY_BLOCK_CACHED:
+ case BLUESKY_BLOCK_DIRTY:
+ break;
+ }
+
+ block->type = BLUESKY_BLOCK_DIRTY;
+}
+
+/* Set the size of a file. This will truncate or extend the file as needed.
+ * Newly-allocated bytes are zeroed. */
+void bluesky_file_truncate(BlueSkyInode *inode, uint64_t size)
+{
+ g_return_if_fail(size <= BLUESKY_MAX_FILE_SIZE);
+
+ if (size == inode->size)
+ return;
+
+ uint64_t blocks = (size + BLUESKY_BLOCK_SIZE - 1) / 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
+ * zero blocks so we don't need to do any more work. */
+ g_array_set_size(inode->blocks, blocks);
+ } else if (blocks < inode->blocks->len) {
+ /* Delete blocks from a file. Must reclaim memory. */
+ for (guint i = inode->blocks->len; i < blocks; i++) {
+ BlueSkyBlock *b = &g_array_index(inode->blocks, BlueSkyBlock, i);
+ g_free(b->ref);
+ g_free(b->data);
+ }
+ g_array_set_size(inode->blocks, blocks);
+ }
+
+ /* If the file size is being decreased, ensure that any trailing data in
+ * the last block is zeroed. */
+ if (size < inode->size) {
+ BlueSkyBlock *b = &g_array_index(inode->blocks, BlueSkyBlock,
+ blocks - 1);
+ if (b->type != BLUESKY_BLOCK_ZERO) {
+ bluesky_block_touch(inode, blocks - 1);
+ int end_offset = size % BLUESKY_BLOCK_SIZE;
+ if (end_offset > 0) {
+ memset(&b->data[end_offset], 0,
+ BLUESKY_BLOCK_SIZE - end_offset);
+ }
+ }
+ }
+
+ inode->size = size;
+ bluesky_inode_update_ctime(inode, 1);
+}
+
+void bluesky_file_write(BlueSkyInode *inode, uint64_t offset,
+ const char *data, gint len)
+{
+ g_return_if_fail(inode->type == BLUESKY_REGULAR);
+ g_return_if_fail(offset < inode->size);
+ g_return_if_fail(len <= inode->size - offset);
+
+ if (len == 0)
+ return;
+
+ 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);
+ BlueSkyBlock *b = &g_array_index(inode->blocks, BlueSkyBlock,
+ block_num);
+ memcpy(&b->data[block_offset], data, bytes);
+ bluesky_block_flush(b);
+
+ offset += bytes;
+ data += bytes;
+ len -= bytes;
+ }
+
+ bluesky_inode_update_ctime(inode, 1);
+}
+
+void bluesky_file_read(BlueSkyInode *inode, uint64_t offset,
+ char *buf, gint len)
+{
+ g_return_if_fail(inode->type == BLUESKY_REGULAR);
+ g_return_if_fail(offset < inode->size);
+ g_return_if_fail(len <= inode->size - offset);
+
+ 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);
+
+ BlueSkyBlock *b = &g_array_index(inode->blocks, BlueSkyBlock,
+ block_num);
+ switch (b->type) {
+ case BLUESKY_BLOCK_ZERO:
+ memset(buf, 0, bytes);
+ break;
+ case BLUESKY_BLOCK_REF:
+ /* TODO: Pull in data first */
+ memset(buf, 0, bytes);
+ break;
+ case BLUESKY_BLOCK_CACHED:
+ case BLUESKY_BLOCK_DIRTY:
+ memcpy(buf, &b->data[block_offset], bytes);
+ break;
+ }
+
+ offset += bytes;
+ buf += bytes;
+ len -= bytes;
+ }
+}
+
+/* Write the given block to cloud-backed storage and mark it clean. */
+void bluesky_block_flush(BlueSkyBlock *block)
+{
+ if (block->type != BLUESKY_BLOCK_DIRTY)
+ return;
+
+ BlueSkyRCStr *data = bluesky_string_new(g_memdup(block->data,
+ BLUESKY_BLOCK_SIZE),
+ BLUESKY_BLOCK_SIZE);
+
+ GChecksum *csum = g_checksum_new(G_CHECKSUM_SHA256);
+ g_checksum_update(csum, data->data, data->len);
+ const gchar *name = g_checksum_get_string(csum);
+
+ g_print("Flushing block as %s\n", name);
+ //memstore_put(store, name, data);
+ g_free(block->ref);
+ block->ref = g_strdup(name);
+ block->type = BLUESKY_BLOCK_CACHED;
+
+ g_checksum_free(csum);
+ bluesky_string_unref(data);
+}