1 /* Blue Sky: File Systems in the Cloud
3 * Copyright (C) 2009 The Regents of the University of California
4 * Written by Michael Vrable <mvrable@cs.ucsd.edu>
14 #include "bluesky-private.h"
16 /* Core filesystem: handling of regular files and caching of file data. */
18 /* Mark a given block dirty and make sure that data is faulted in so that it
19 * can be written to. */
20 void bluesky_block_touch(BlueSkyInode *inode, uint64_t i)
22 g_return_if_fail(i < inode->blocks->len);
23 BlueSkyBlock *block = &g_array_index(inode->blocks, BlueSkyBlock, i);
26 if (i < inode->blocks->len - 1) {
27 block_len = BLUESKY_BLOCK_SIZE;
29 block_len = inode->size - i * BLUESKY_BLOCK_SIZE;
32 switch (block->type) {
33 case BLUESKY_BLOCK_ZERO:
34 g_print("Allocating zero block of size %zd\n", block_len);
35 block->data = bluesky_string_new(g_malloc0(block_len), block_len);
37 case BLUESKY_BLOCK_REF:
38 bluesky_block_fetch(inode->fs, block);
39 g_assert(block->type == BLUESKY_BLOCK_CACHED);
41 case BLUESKY_BLOCK_CACHED:
42 case BLUESKY_BLOCK_DIRTY:
43 block->data = bluesky_string_dup(block->data);
47 block->type = BLUESKY_BLOCK_DIRTY;
50 /* Set the size of a file. This will truncate or extend the file as needed.
51 * Newly-allocated bytes are zeroed. */
52 void bluesky_file_truncate(BlueSkyInode *inode, uint64_t size)
54 g_return_if_fail(size <= BLUESKY_MAX_FILE_SIZE);
56 if (size == inode->size)
59 g_print("Truncating file to %"PRIi64" bytes\n", size);
61 uint64_t blocks = (size + BLUESKY_BLOCK_SIZE - 1) / BLUESKY_BLOCK_SIZE;
63 if (blocks > inode->blocks->len) {
64 /* Need to add new blocks to the end of a file. New block structures
65 * are automatically zeroed, which initializes them to be pointers to
66 * zero blocks so we don't need to do any more work. */
67 g_array_set_size(inode->blocks, blocks);
68 } else if (blocks < inode->blocks->len) {
69 /* Delete blocks from a file. Must reclaim memory. */
70 for (guint i = inode->blocks->len; i < blocks; i++) {
71 BlueSkyBlock *b = &g_array_index(inode->blocks, BlueSkyBlock, i);
73 bluesky_string_unref(b->data);
75 g_array_set_size(inode->blocks, blocks);
78 /* Ensure the last block of the file is properly sized. If the block is
79 * extended, newly-added bytes must be zeroed. */
81 BlueSkyBlock *b = &g_array_index(inode->blocks, BlueSkyBlock,
84 if (b->type != BLUESKY_BLOCK_ZERO) {
85 bluesky_block_touch(inode, blocks - 1);
86 gsize old_size = b->data->len;
87 gsize new_size = size - (blocks - 1) * BLUESKY_BLOCK_SIZE;
89 bluesky_string_resize(b->data, new_size);
91 if (new_size > old_size) {
92 memset(&b->data->data[old_size], 0, new_size - old_size);
98 bluesky_inode_update_ctime(inode, 1);
101 void bluesky_file_write(BlueSkyInode *inode, uint64_t offset,
102 const char *data, gint len)
104 g_print("Write %d bytes at offset %"PRIi64"\n", len, offset);
106 g_return_if_fail(inode->type == BLUESKY_REGULAR);
107 g_return_if_fail(offset < inode->size);
108 g_return_if_fail(len <= inode->size - offset);
114 uint64_t block_num = offset / BLUESKY_BLOCK_SIZE;
115 gint block_offset = offset % BLUESKY_BLOCK_SIZE;
116 gint bytes = MIN(BLUESKY_BLOCK_SIZE - block_offset, len);
118 bluesky_block_touch(inode, block_num);
119 BlueSkyBlock *b = &g_array_index(inode->blocks, BlueSkyBlock,
121 memcpy(&b->data->data[block_offset], data, bytes);
122 bluesky_block_flush(inode->fs, b);
129 bluesky_inode_update_ctime(inode, 1);
130 bluesky_inode_flush(inode->fs, inode);
133 void bluesky_file_read(BlueSkyInode *inode, uint64_t offset,
136 g_print("Read %d bytes at offset %"PRIi64"\n", len, offset);
138 if (len == 0 && offset <= inode->size)
141 g_return_if_fail(inode->type == BLUESKY_REGULAR);
142 g_return_if_fail(offset < inode->size);
143 g_return_if_fail(len <= inode->size - offset);
146 uint64_t block_num = offset / BLUESKY_BLOCK_SIZE;
147 gint block_offset = offset % BLUESKY_BLOCK_SIZE;
148 gint bytes = MIN(BLUESKY_BLOCK_SIZE - block_offset, len);
150 BlueSkyBlock *b = &g_array_index(inode->blocks, BlueSkyBlock,
153 case BLUESKY_BLOCK_ZERO:
154 memset(buf, 0, bytes);
156 case BLUESKY_BLOCK_REF:
157 bluesky_block_fetch(inode->fs, b);
159 case BLUESKY_BLOCK_CACHED:
160 case BLUESKY_BLOCK_DIRTY:
161 memcpy(buf, &b->data->data[block_offset], bytes);
171 /* Read the given block from cloud-backed storage if the data is not already
173 void bluesky_block_fetch(BlueSkyFS *fs, BlueSkyBlock *block)
175 if (block->type != BLUESKY_BLOCK_REF)
178 BlueSkyRCStr *string = bluesky_store_get(fs->store, block->ref);
180 bluesky_string_unref(block->data);
181 block->data = string;
182 block->type = BLUESKY_BLOCK_CACHED;
185 /* Write the given block to cloud-backed storage and mark it clean. */
186 void bluesky_block_flush(BlueSkyFS *fs, BlueSkyBlock *block)
188 if (block->type != BLUESKY_BLOCK_DIRTY)
191 BlueSkyRCStr *data = block->data;
193 GChecksum *csum = g_checksum_new(G_CHECKSUM_SHA256);
194 g_checksum_update(csum, data->data, data->len);
195 gchar *name = g_strdup(g_checksum_get_string(csum));
197 /* Store the file data asynchronously, and don't bother waiting for a
199 BlueSkyStoreAsync *async = bluesky_store_async_new(fs->store);
200 async->op = STORE_OP_PUT;
201 async->key = g_strdup(name);
202 bluesky_string_ref(data);
204 bluesky_store_async_submit(async);
205 bluesky_store_async_unref(async);
210 /* block->type = BLUESKY_BLOCK_CACHED; */
211 bluesky_string_unref(block->data);
213 block->type = BLUESKY_BLOCK_REF;
215 g_checksum_free(csum);
216 //bluesky_string_unref(data);
219 /* Flush all blocks in a file to stable storage. */
220 void bluesky_file_flush(BlueSkyInode *inode)
222 g_return_if_fail(inode->type == BLUESKY_REGULAR);
224 for (int i = 0; i < inode->blocks->len; i++) {
225 BlueSkyBlock *b = &g_array_index(inode->blocks, BlueSkyBlock, i);
226 bluesky_block_flush(inode->fs, b);