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>
15 #include "bluesky-private.h"
17 /* Core filesystem. Different proxies, such as the NFSv3 one, interface to
18 * this, but the core actually tracks the data which is stored. So far we just
19 * implement an in-memory filesystem, but eventually this will be state which
20 * is persisted to the cloud. */
22 /* Return the current time, in microseconds since the epoch. */
23 int64_t bluesky_get_current_time()
26 g_get_current_time(&t);
27 return (int64_t)t.tv_sec * 1000000 + t.tv_usec;
30 /* Update an inode to indicate that a modification was made. This increases
31 * the change counter, updates the ctime to the current time, and optionally
32 * updates the mtime. This also makes the inode contents subject to writeback
33 * to storage in the future. inode must already be locked. */
34 void bluesky_inode_update_ctime(BlueSkyInode *inode, gboolean update_mtime)
36 int64_t now = bluesky_get_current_time();
37 inode->change_count++;
42 if (inode->change_time == 0)
43 inode->change_time = now;
46 if (bluesky_options.writethrough_cache)
47 bluesky_file_flush(inode, NULL);
50 g_mutex_lock(inode->fs->lock);
51 bluesky_list_unlink(&inode->fs->unlogged_list, inode->unlogged_list);
52 inode->unlogged_list = bluesky_list_prepend(&inode->fs->unlogged_list, inode);
53 bluesky_list_unlink(&inode->fs->accessed_list, inode->accessed_list);
54 inode->accessed_list = bluesky_list_prepend(&inode->fs->accessed_list, inode);
55 g_mutex_unlock(inode->fs->lock);
58 /* Unfortunately a glib hash table is only guaranteed to be able to store
59 * 32-bit keys if we use the key directly. If we want 64-bit inode numbers,
60 * we'll have to allocate memory to store the 64-bit inumber, and use a pointer
61 * to it. Rather than allocate the memory for the key, we'll just include a
62 * pointer to the 64-bit inum stored in the inode itself, so that we don't need
63 * to do any more memory management. */
64 static guint bluesky_fs_key_hash_func(gconstpointer key)
66 uint64_t inum = *(const uint64_t *)key;
70 static gboolean bluesky_fs_key_equal_func(gconstpointer a, gconstpointer b)
72 uint64_t i1 = *(const uint64_t *)a;
73 uint64_t i2 = *(const uint64_t *)b;
77 /* Filesystem-level operations. A filesystem is like a directory tree that we
78 * are willing to export. */
79 BlueSkyFS *bluesky_new_fs(gchar *name)
81 BlueSkyFS *fs = g_new0(BlueSkyFS, 1);
82 fs->lock = g_mutex_new();
83 fs->name = g_strdup(name);
84 fs->inodes = g_hash_table_new(bluesky_fs_key_hash_func,
85 bluesky_fs_key_equal_func);
86 fs->next_inum = BLUESKY_ROOT_INUM + 1;
87 fs->store = bluesky_store_new("file");
88 fs->flushd_lock = g_mutex_new();
89 fs->flushd_cond = g_cond_new();
90 fs->locations = g_hash_table_new(bluesky_cloudlog_hash,
91 bluesky_cloudlog_equal);
92 fs->inode_map = g_sequence_new(NULL);
94 fs->log_state = g_new0(BlueSkyCloudLogState, 1);
95 fs->log_state->data = g_string_new("");
100 BlueSkyFS *bluesky_init_fs(gchar *name, BlueSkyStore *store)
102 BlueSkyRCStr *data = bluesky_store_get(store, "superblock");
104 BlueSkyFS *fs = bluesky_deserialize_superblock(data->data);
107 fs->log = bluesky_log_new("journal");
109 g_print("Loaded filesystem superblock\n");
111 fs->name = g_strdup(name);
114 bluesky_string_unref(data);
117 g_print("Initializing fresh filesystem\n");
118 BlueSkyFS *fs = bluesky_new_fs(name);
120 fs->log = bluesky_log_new("journal");
123 BlueSkyInode *root = bluesky_new_inode(BLUESKY_ROOT_INUM, fs,
127 bluesky_insert_inode(fs, root);
128 bluesky_inode_update_ctime(root, TRUE);
130 bluesky_inode_do_sync(root);
131 bluesky_superblock_flush(fs);
136 /* Inode reference counting. */
137 void bluesky_inode_ref(BlueSkyInode *inode)
139 g_atomic_int_inc(&inode->refcount);
142 void bluesky_inode_unref(BlueSkyInode *inode)
144 if (g_atomic_int_dec_and_test(&inode->refcount)) {
145 if (bluesky_verbose) {
146 g_log("bluesky/inode", G_LOG_LEVEL_DEBUG,
147 "Reference count for inode %"PRIu64" dropped to zero.",
151 /* Sanity check: Is the inode clean? */
152 if (inode->change_commit < inode->change_count
153 || inode->accessed_list != NULL
154 || inode->unlogged_list != NULL
155 || inode->dirty_list != NULL) {
156 g_warning("Dropping inode which is not clean (commit %"PRIi64" < change %"PRIi64"; accessed_list = %p; dirty_list = %p)\n", inode->change_commit, inode->change_count, inode->accessed_list, inode->dirty_list);
159 /* These shouldn't be needed, but in case the above warning fires and
160 * we delete the inode anyway, we ought to be sure the inode is not on
162 g_mutex_lock(inode->fs->lock);
163 bluesky_list_unlink(&inode->fs->accessed_list, inode->accessed_list);
164 bluesky_list_unlink(&inode->fs->dirty_list, inode->dirty_list);
165 bluesky_list_unlink(&inode->fs->unlogged_list, inode->unlogged_list);
166 g_mutex_unlock(inode->fs->lock);
168 /* Free file type specific data. It should be an error for there to be
169 * dirty data to commit when the reference count has reaches zero. */
170 switch (inode->type) {
171 case BLUESKY_REGULAR:
172 for (int i = 0; i < inode->blocks->len; i++) {
173 BlueSkyBlock *b = &g_array_index(inode->blocks,
175 if (b->type == BLUESKY_BLOCK_DIRTY) {
176 g_error("Deleting an inode with dirty file data!");
178 bluesky_cloudlog_unref(b->ref);
179 bluesky_string_unref(b->dirty);
181 g_array_unref(inode->blocks);
184 case BLUESKY_DIRECTORY:
185 g_hash_table_destroy(inode->dirhash);
186 g_hash_table_destroy(inode->dirhash_folded);
187 g_sequence_free(inode->dirents);
190 case BLUESKY_SYMLINK:
191 g_free(inode->symlink_contents);
198 g_mutex_free(inode->lock);
204 /* Allocate a fresh inode number which has not been used before within a
205 * filesystem. fs must already be locked. */
206 uint64_t bluesky_fs_alloc_inode(BlueSkyFS *fs)
210 inum = fs->next_inum;
213 bluesky_superblock_flush(fs);
218 /* Perform type-specification initialization of an inode. Normally performed
219 * in bluesky_new_inode, but can be separated if an inode is created first,
220 * then deserialized. */
221 void bluesky_init_inode(BlueSkyInode *i, BlueSkyFileType type)
226 case BLUESKY_REGULAR:
227 i->blocks = g_array_new(FALSE, TRUE, sizeof(BlueSkyBlock));
229 case BLUESKY_DIRECTORY:
230 i->dirents = g_sequence_new(bluesky_dirent_destroy);
231 i->dirhash = g_hash_table_new(g_str_hash, g_str_equal);
232 i->dirhash_folded = g_hash_table_new(g_str_hash, g_str_equal);
239 BlueSkyInode *bluesky_new_inode(uint64_t inum, BlueSkyFS *fs,
240 BlueSkyFileType type)
242 BlueSkyInode *i = g_new0(BlueSkyInode, 1);
244 i->lock = g_mutex_new();
249 bluesky_init_inode(i, type);
254 /* Retrieve an inode from the filesystem. Eventually this will be a cache and
255 * so we might need to go fetch the inode from elsewhere; for now all
256 * filesystem state is stored here. inode is returned with a reference held
258 BlueSkyInode *bluesky_get_inode(BlueSkyFS *fs, uint64_t inum)
260 BlueSkyInode *inode = NULL;
266 g_mutex_lock(fs->lock);
267 inode = (BlueSkyInode *)g_hash_table_lookup(fs->inodes, &inum);
270 bluesky_inode_fetch(fs, inum);
271 inode = (BlueSkyInode *)g_hash_table_lookup(fs->inodes, &inum);
275 bluesky_inode_ref(inode);
277 /* FIXME: We assume we can atomically update the in-memory access time
279 inode->access_time = bluesky_get_current_time();
282 g_mutex_unlock(fs->lock);
287 /* Insert an inode into the filesystem inode cache. fs should be locked. */
288 void bluesky_insert_inode(BlueSkyFS *fs, BlueSkyInode *inode)
290 g_hash_table_insert(fs->inodes, &inode->inum, inode);
293 /* Start writeback of an inode and all associated data. */
294 void bluesky_inode_start_sync(BlueSkyInode *inode)
296 GList *log_items = NULL;
298 if (inode->type == BLUESKY_REGULAR)
299 bluesky_file_flush(inode, &log_items);
301 BlueSkyCloudLog *cloudlog = bluesky_serialize_inode(inode);
303 bluesky_cloudlog_unref(inode->committed_item);
304 inode->committed_item = cloudlog;
306 bluesky_cloudlog_sync(cloudlog);
307 bluesky_cloudlog_ref(cloudlog);
308 log_items = g_list_prepend(log_items, cloudlog);
310 /* Wait for all log items to be committed to disk. */
311 bluesky_log_finish_all(log_items);
313 /* Mark the inode as clean */
314 inode->change_commit = inode->change_count;
315 inode->change_time = 0;
316 g_mutex_lock(inode->fs->lock);
317 bluesky_list_unlink(&inode->fs->unlogged_list, inode->unlogged_list);
318 inode->unlogged_list = NULL;
320 /* Since a new version of the inode has been written to the log, also
321 * schedule a future flush of the new data to cloud storage. */
322 bluesky_list_unlink(&inode->fs->dirty_list, inode->dirty_list);
323 inode->dirty_list = bluesky_list_prepend(&inode->fs->dirty_list, inode);
324 inode->change_cloud = inode->change_count;
326 g_mutex_unlock(inode->fs->lock);
329 /* Write back an inode and all associated data and wait for completion. Inode
330 * should already be locked. */
331 void bluesky_inode_do_sync(BlueSkyInode *inode)
333 if (bluesky_verbose) {
334 g_log("bluesky/inode", G_LOG_LEVEL_DEBUG,
335 "Synchronous writeback for inode %"PRIu64"...", inode->inum);
337 bluesky_inode_start_sync(inode);
338 if (bluesky_verbose) {
339 g_log("bluesky/inode", G_LOG_LEVEL_DEBUG,
340 "Writeback for inode %"PRIu64" complete", inode->inum);
344 static void complete_inode_fetch(BlueSkyStoreAsync *async, BlueSkyInode *inode)
346 if (bluesky_verbose) {
347 g_log("bluesky/inode", G_LOG_LEVEL_DEBUG,
348 "Completing fetch of inode %"PRIu64"...", inode->inum);
351 if (async->result != 0
352 || !bluesky_deserialize_inode(inode, async->data->data))
354 if (bluesky_verbose) {
355 g_log("bluesky/inode", G_LOG_LEVEL_DEBUG,
356 " failed to load inode, cleaning up");
358 g_mutex_lock(inode->fs->lock);
359 g_hash_table_remove(inode->fs->inodes, &inode->inum);
360 bluesky_list_unlink(&inode->fs->accessed_list, inode->accessed_list);
361 inode->accessed_list = NULL;
362 g_mutex_unlock(inode->fs->lock);
363 bluesky_inode_unref(inode);
366 inode->access_time = bluesky_get_current_time();
367 g_mutex_lock(inode->fs->lock);
368 bluesky_list_unlink(&inode->fs->accessed_list, inode->accessed_list);
369 inode->accessed_list = bluesky_list_prepend(&inode->fs->accessed_list, inode);
370 g_mutex_unlock(inode->fs->lock);
372 g_mutex_unlock(inode->lock);
373 bluesky_inode_unref(inode);
376 /* Fetch an inode from stable storage. The fetch can be performed
377 * asynchronously: the in-memory inode is allocated, but not filled with data
378 * immediately. It is kept locked until it has been filled in, so any users
379 * should try to acquire the lock on the inode before accessing any data. The
380 * fs lock must be held. */
381 void bluesky_inode_fetch(BlueSkyFS *fs, uint64_t inum)
384 sprintf(key, "inode-%016"PRIx64, inum);
386 BlueSkyInode *inode = bluesky_new_inode(inum, fs, BLUESKY_PENDING);
387 inode->change_count = 0;
388 bluesky_inode_ref(inode); // Extra ref held by fetching process
389 g_mutex_lock(inode->lock);
390 bluesky_insert_inode(fs, inode);
392 BlueSkyStoreAsync *async = bluesky_store_async_new(fs->store);
393 async->op = STORE_OP_GET;
394 async->key = g_strdup(key);
396 bluesky_store_async_add_notifier(async, (GFunc)complete_inode_fetch, inode);
397 bluesky_store_async_submit(async);
399 if (bluesky_options.sync_inode_fetches) {
400 bluesky_store_async_wait(async);
403 bluesky_store_async_unref(async);
406 /* Synchronize filesystem superblock to stable storage. */
407 void bluesky_superblock_flush(BlueSkyFS *fs)
410 GString *buf = g_string_new("");
411 bluesky_serialize_superblock(buf, fs);
412 BlueSkyRCStr *data = bluesky_string_new_from_gstring(buf);
414 BlueSkyStoreAsync *async = bluesky_store_async_new(fs->store);
415 async->op = STORE_OP_PUT;
416 async->key = g_strdup("superblock");
418 bluesky_store_async_submit(async);
419 bluesky_store_async_unref(async);
421 //bluesky_store_sync(fs->store);