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 /* Core filesystem. Different proxies, such as the NFSv3 one, interface to
16 * this, but the core actually tracks the data which is stored. So far we just
17 * implement an in-memory filesystem, but eventually this will be state which
18 * is persisted to the cloud. */
20 /* Return the current time, in microseconds since the epoch. */
21 int64_t bluesky_get_current_time()
24 g_get_current_time(&t);
25 return (int64_t)t.tv_sec * 1000000 + t.tv_usec;
28 /* Update an inode to indicate that a modification was made. This increases
29 * the change counter, updates the ctime to the current time, and optionally
30 * updates the mtime. */
31 void bluesky_inode_update_ctime(BlueSkyInode *inode, gboolean update_mtime)
33 int64_t now = bluesky_get_current_time();
34 inode->change_count++;
40 /* Unfortunately a glib hash table is only guaranteed to be able to store
41 * 32-bit keys if we use the key directly. If we want 64-bit inode numbers,
42 * we'll have to allocate memory to store the 64-bit inumber, and use a pointer
43 * to it. Rather than allocate the memory for the key, we'll just include a
44 * pointer to the 64-bit inum stored in the inode itself, so that we don't need
45 * to do any more memory management. */
46 static guint bluesky_fs_key_hash_func(gconstpointer key)
48 uint64_t inum = *(const uint64_t *)key;
52 static gboolean bluesky_fs_key_equal_func(gconstpointer a, gconstpointer b)
54 uint64_t i1 = *(const uint64_t *)a;
55 uint64_t i2 = *(const uint64_t *)b;
59 /* Filesystem-level operations. A filesystem is like a directory tree that we
60 * are willing to export. */
61 BlueSkyFS *bluesky_new_fs(gchar *name)
63 BlueSkyFS *fs = g_new0(BlueSkyFS, 1);
64 fs->lock = g_mutex_new();
65 fs->name = g_strdup(name);
66 fs->inodes = g_hash_table_new(bluesky_fs_key_hash_func,
67 bluesky_fs_key_equal_func);
68 fs->next_inum = BLUESKY_ROOT_INUM + 1;
69 fs->store = bluesky_store_new("file");
74 /* Inode reference counting. */
75 void bluesky_inode_ref(BlueSkyInode *inode)
77 g_atomic_int_inc(&inode->refcount);
80 void bluesky_inode_unref(BlueSkyInode *inode)
82 if (g_atomic_int_dec_and_test(&inode->refcount)) {
83 g_error("Reference count for inode %lld dropped to zero!\n",
88 /* Allocate a fresh inode number which has not been used before within a
90 uint64_t bluesky_fs_alloc_inode(BlueSkyFS *fs)
94 g_mutex_lock(fs->lock);
97 g_mutex_unlock(fs->lock);
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);
122 case BLUESKY_CHARACTER:
123 case BLUESKY_SYMLINK:
132 /* Retrieve an inode from the filesystem. Eventually this will be a cache and
133 * so we might need to go fetch the inode from elsewhere; for now all
134 * filesystem state is stored here. */
135 BlueSkyInode *bluesky_get_inode(BlueSkyFS *fs, uint64_t inum)
137 BlueSkyInode *inode = NULL;
139 g_mutex_lock(fs->lock);
140 inode = (BlueSkyInode *)g_hash_table_lookup(fs->inodes, &inum);
141 g_mutex_unlock(fs->lock);
146 /* Insert an inode into the filesystem inode cache. */
147 void bluesky_insert_inode(BlueSkyFS *fs, BlueSkyInode *inode)
149 g_mutex_lock(fs->lock);
150 g_hash_table_insert(fs->inodes, &inode->inum, inode);
151 g_mutex_unlock(fs->lock);