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 /* Unfortunately a glib hash table is only guaranteed to be able to store
47 * 32-bit keys if we use the key directly. If we want 64-bit inode numbers,
48 * we'll have to allocate memory to store the 64-bit inumber, and use a pointer
49 * to it. Rather than allocate the memory for the key, we'll just include a
50 * pointer to the 64-bit inum stored in the inode itself, so that we don't need
51 * to do any more memory management. */
52 static guint bluesky_fs_key_hash_func(gconstpointer key)
54 uint64_t inum = *(const uint64_t *)key;
58 static gboolean bluesky_fs_key_equal_func(gconstpointer a, gconstpointer b)
60 uint64_t i1 = *(const uint64_t *)a;
61 uint64_t i2 = *(const uint64_t *)b;
65 /* Filesystem-level operations. A filesystem is like a directory tree that we
66 * are willing to export. */
67 BlueSkyFS *bluesky_new_fs(gchar *name)
69 BlueSkyFS *fs = g_new0(BlueSkyFS, 1);
70 fs->lock = g_mutex_new();
71 fs->name = g_strdup(name);
72 fs->inodes = g_hash_table_new(bluesky_fs_key_hash_func,
73 bluesky_fs_key_equal_func);
74 fs->next_inum = BLUESKY_ROOT_INUM + 1;
75 fs->store = bluesky_store_new("file");
80 BlueSkyFS *bluesky_init_fs(gchar *name, BlueSkyStore *store)
82 BlueSkyRCStr *data = bluesky_store_get(store, "superblock");
84 BlueSkyFS *fs = bluesky_deserialize_superblock(data->data);
87 g_print("Loaded filesystem superblock\n");
89 fs->name = g_strdup(name);
94 g_print("Initializing fresh filesystem\n");
95 BlueSkyFS *fs = bluesky_new_fs(name);
98 BlueSkyInode *root = bluesky_new_inode(BLUESKY_ROOT_INUM, fs,
102 bluesky_insert_inode(fs, root);
104 bluesky_inode_flush(fs, root);
105 bluesky_superblock_flush(fs);
110 /* Inode reference counting. */
111 void bluesky_inode_ref(BlueSkyInode *inode)
113 g_atomic_int_inc(&inode->refcount);
116 void bluesky_inode_unref(BlueSkyInode *inode)
118 if (g_atomic_int_dec_and_test(&inode->refcount)) {
119 g_error("Reference count for inode %"PRIu64" dropped to zero!\n",
124 /* Allocate a fresh inode number which has not been used before within a
125 * filesystem. fs must already be locked. */
126 uint64_t bluesky_fs_alloc_inode(BlueSkyFS *fs)
130 inum = fs->next_inum;
133 bluesky_superblock_flush(fs);
138 BlueSkyInode *bluesky_new_inode(uint64_t inum, BlueSkyFS *fs,
139 BlueSkyFileType type)
141 BlueSkyInode *i = g_new0(BlueSkyInode, 1);
143 i->lock = g_mutex_new();
150 case BLUESKY_REGULAR:
151 i->blocks = g_array_new(FALSE, TRUE, sizeof(BlueSkyBlock));
153 case BLUESKY_DIRECTORY:
154 i->dirents = g_sequence_new(bluesky_dirent_destroy);
155 i->dirhash = g_hash_table_new(g_str_hash, g_str_equal);
156 i->dirhash_folded = g_hash_table_new(g_str_hash, g_str_equal);
159 case BLUESKY_CHARACTER:
160 case BLUESKY_SYMLINK:
169 /* Retrieve an inode from the filesystem. Eventually this will be a cache and
170 * so we might need to go fetch the inode from elsewhere; for now all
171 * filesystem state is stored here. inode is returned locked with a reference
173 BlueSkyInode *bluesky_get_inode(BlueSkyFS *fs, uint64_t inum)
175 BlueSkyInode *inode = NULL;
181 g_mutex_lock(fs->lock);
182 inode = (BlueSkyInode *)g_hash_table_lookup(fs->inodes, &inum);
185 bluesky_inode_fetch(fs, inum);
186 inode = (BlueSkyInode *)g_hash_table_lookup(fs->inodes, &inum);
190 bluesky_inode_ref(inode);
193 g_mutex_unlock(fs->lock);
198 /* Insert an inode into the filesystem inode cache. fs should be locked. */
199 void bluesky_insert_inode(BlueSkyFS *fs, BlueSkyInode *inode)
201 g_hash_table_insert(fs->inodes, &inode->inum, inode);
204 /* Deprecated: Synchronize an inode to stable storage. */
205 void bluesky_inode_flush(BlueSkyFS *fs, BlueSkyInode *inode)
207 GString *buf = g_string_new("");
208 bluesky_serialize_inode(buf, inode);
209 BlueSkyRCStr *data = bluesky_string_new_from_gstring(buf);
212 sprintf(key, "inode-%016"PRIx64, inode->inum);
214 BlueSkyStoreAsync *async = bluesky_store_async_new(fs->store);
215 async->op = STORE_OP_PUT;
216 async->key = g_strdup(key);
218 bluesky_store_async_submit(async);
219 bluesky_store_async_unref(async);
222 /* Start writeback of an inode and all associated data. */
223 void bluesky_inode_start_sync(BlueSkyInode *inode, BlueSkyStoreAsync *barrier)
225 BlueSkyFS *fs = inode->fs;
227 GString *buf = g_string_new("");
228 bluesky_serialize_inode(buf, inode);
229 BlueSkyRCStr *data = bluesky_string_new_from_gstring(buf);
231 if (inode->type == BLUESKY_REGULAR)
232 bluesky_file_flush(inode, barrier);
235 sprintf(key, "inode-%016"PRIx64, inode->inum);
237 BlueSkyStoreAsync *async = bluesky_store_async_new(fs->store);
238 async->op = STORE_OP_PUT;
239 async->key = g_strdup(key);
241 bluesky_store_async_submit(async);
243 bluesky_store_add_barrier(barrier, async);
244 bluesky_store_async_unref(async);
247 /* Fetch an inode from stable storage. */
248 void bluesky_inode_fetch(BlueSkyFS *fs, uint64_t inum)
251 sprintf(key, "inode-%016"PRIx64, inum);
252 BlueSkyRCStr *data = bluesky_store_get(fs->store, key);
256 BlueSkyInode *inode = bluesky_deserialize_inode(fs, data->data);
258 bluesky_insert_inode(fs, inode);
262 /* Synchronize filesystem superblock to stable storage. */
263 void bluesky_superblock_flush(BlueSkyFS *fs)
265 GString *buf = g_string_new("");
266 bluesky_serialize_superblock(buf, fs);
267 BlueSkyRCStr *data = bluesky_string_new_from_gstring(buf);
269 BlueSkyStoreAsync *async = bluesky_store_async_new(fs->store);
270 async->op = STORE_OP_PUT;
271 async->key = g_strdup("superblock");
273 bluesky_store_async_submit(async);
274 bluesky_store_async_unref(async);
276 bluesky_store_sync(fs->store);