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>
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. inode must already be locked. */
33 void bluesky_inode_update_ctime(BlueSkyInode *inode, gboolean update_mtime)
35 int64_t now = bluesky_get_current_time();
36 inode->change_count++;
42 /* Unfortunately a glib hash table is only guaranteed to be able to store
43 * 32-bit keys if we use the key directly. If we want 64-bit inode numbers,
44 * we'll have to allocate memory to store the 64-bit inumber, and use a pointer
45 * to it. Rather than allocate the memory for the key, we'll just include a
46 * pointer to the 64-bit inum stored in the inode itself, so that we don't need
47 * to do any more memory management. */
48 static guint bluesky_fs_key_hash_func(gconstpointer key)
50 uint64_t inum = *(const uint64_t *)key;
54 static gboolean bluesky_fs_key_equal_func(gconstpointer a, gconstpointer b)
56 uint64_t i1 = *(const uint64_t *)a;
57 uint64_t i2 = *(const uint64_t *)b;
61 /* Filesystem-level operations. A filesystem is like a directory tree that we
62 * are willing to export. */
63 BlueSkyFS *bluesky_new_fs(gchar *name)
65 BlueSkyFS *fs = g_new0(BlueSkyFS, 1);
66 fs->lock = g_mutex_new();
67 fs->name = g_strdup(name);
68 fs->inodes = g_hash_table_new(bluesky_fs_key_hash_func,
69 bluesky_fs_key_equal_func);
70 fs->next_inum = BLUESKY_ROOT_INUM + 1;
71 fs->store = bluesky_store_new("file");
76 /* Inode reference counting. */
77 void bluesky_inode_ref(BlueSkyInode *inode)
79 g_atomic_int_inc(&inode->refcount);
82 void bluesky_inode_unref(BlueSkyInode *inode)
84 if (g_atomic_int_dec_and_test(&inode->refcount)) {
85 g_error("Reference count for inode %"PRIu64" dropped to zero!\n",
90 /* Allocate a fresh inode number which has not been used before within a
91 * filesystem. fs must already be locked. */
92 uint64_t bluesky_fs_alloc_inode(BlueSkyFS *fs)
102 BlueSkyInode *bluesky_new_inode(uint64_t inum, BlueSkyFS *fs,
103 BlueSkyFileType type)
105 BlueSkyInode *i = g_new0(BlueSkyInode, 1);
107 i->lock = g_mutex_new();
114 case BLUESKY_REGULAR:
115 i->blocks = g_array_new(FALSE, TRUE, sizeof(BlueSkyBlock));
117 case BLUESKY_DIRECTORY:
118 i->dirents = g_sequence_new(bluesky_dirent_destroy);
119 i->dirhash = g_hash_table_new(g_str_hash, g_str_equal);
120 i->dirhash_folded = g_hash_table_new(g_str_hash, g_str_equal);
123 case BLUESKY_CHARACTER:
124 case BLUESKY_SYMLINK:
133 /* Retrieve an inode from the filesystem. Eventually this will be a cache and
134 * so we might need to go fetch the inode from elsewhere; for now all
135 * filesystem state is stored here. inode is returned locked with a reference
137 BlueSkyInode *bluesky_get_inode(BlueSkyFS *fs, uint64_t inum)
139 BlueSkyInode *inode = NULL;
141 g_mutex_lock(fs->lock);
142 inode = (BlueSkyInode *)g_hash_table_lookup(fs->inodes, &inum);
145 bluesky_inode_fetch(fs, inum);
146 inode = (BlueSkyInode *)g_hash_table_lookup(fs->inodes, &inum);
150 bluesky_inode_ref(inode);
153 g_mutex_unlock(fs->lock);
158 /* Insert an inode into the filesystem inode cache. fs should be locked. */
159 void bluesky_insert_inode(BlueSkyFS *fs, BlueSkyInode *inode)
161 g_hash_table_insert(fs->inodes, &inode->inum, inode);
164 /* Synchronize an inode to stable storage. */
165 void bluesky_inode_flush(BlueSkyFS *fs, BlueSkyInode *inode)
167 GString *buf = g_string_new("");
168 bluesky_serialize_inode(buf, inode);
170 gsize len = buf->len;
171 BlueSkyRCStr *data = bluesky_string_new(g_string_free(buf, FALSE), len);
174 sprintf(key, "inode-%016"PRIx64, inode->inum);
176 bluesky_store_put(fs->store, key, data);
179 /* Fetch an inode from stable storage. */
180 void bluesky_inode_fetch(BlueSkyFS *fs, uint64_t inum)
183 sprintf(key, "inode-%016"PRIx64, inum);
184 BlueSkyRCStr *data = bluesky_store_get(fs->store, key);
188 BlueSkyInode *inode = bluesky_deserialize_inode(fs, data->data);
190 bluesky_insert_inode(fs, inode);
191 g_print("Loaded inode %"PRIu64"\n", inum);