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>
20 /* Various options to tweak for performance benchmarking purposes. */
22 /* Perform all get/put operations synchronously. */
23 int synchronous_stores;
25 /* Write data in cache immediately after file is modified. */
26 int writethrough_cache;
28 /* Can inodes be fetched asynchronously? (Inode object is initially
29 * created in a pending state, and not unlocked until the data is actually
31 int sync_inode_fetches;
33 /* Should frontends handle requests serially or allow operations to proceed
38 extern BlueSkyOptions bluesky_options;
40 /* BlueSky status and error codes. Various frontends should translate these to
41 * the appropriate error code for whatever protocol they implement. */
43 BSTATUS_OK = 0, /* No error */
44 BSTATUS_IOERR, /* I/O error of some form */
45 BSTATUS_NOENT, /* File does not exist */
48 void bluesky_init(void);
50 gchar *bluesky_lowercase(const gchar *s);
52 /* Reference-counted blocks of memory, used for passing data in and out of
53 * storage backends and in other places. */
60 BlueSkyRCStr *bluesky_string_new(gpointer data, gsize len);
61 BlueSkyRCStr *bluesky_string_new_from_gstring(GString *s);
62 void bluesky_string_ref(BlueSkyRCStr *string);
63 void bluesky_string_unref(BlueSkyRCStr *string);
64 BlueSkyRCStr *bluesky_string_dup(BlueSkyRCStr *string);
65 void bluesky_string_resize(BlueSkyRCStr *string, gsize len);
67 /* Cryptographic operations. */
68 #define CRYPTO_BLOCK_SIZE 16 /* 128-bit AES */
69 #define CRYPTO_KEY_SIZE 16
71 void bluesky_crypt_init();
72 void bluesky_crypt_hash_key(const char *keystr, uint8_t *out);
73 void bluesky_crypt_random_bytes(guchar *buf, gint len);
74 BlueSkyRCStr *bluesky_crypt_encrypt(BlueSkyRCStr *in, const uint8_t *key);
75 BlueSkyRCStr *bluesky_crypt_decrypt(BlueSkyRCStr *in, const uint8_t *key);
77 /* Storage interface. This presents a key-value store abstraction, and can
78 * have multiple implementations: in-memory, on-disk, in-cloud. */
80 typedef struct _BlueSkyStore BlueSkyStore;
82 void bluesky_store_init();
83 BlueSkyStore *bluesky_store_new(const gchar *type);
84 void bluesky_store_free(BlueSkyStore *store);
85 BlueSkyRCStr *bluesky_store_get(BlueSkyStore *store, const gchar *key);
86 void bluesky_store_put(BlueSkyStore *store,
87 const gchar *key, BlueSkyRCStr *val);
89 /* File types. The numeric values are chosen to match with those used in
93 BLUESKY_DIRECTORY = 2,
95 BLUESKY_CHARACTER = 4,
100 /* Special types used only internally. */
101 BLUESKY_PENDING = 0, /* Inode being loaded; type not yet determined */
102 BLUESKY_INVALID = -1, /* Inode is invalid (failed to load) */
105 /* Filesystem state. Each filesystem which is exported is represented by a
106 * single bluesky_fs structure in memory. */
110 gchar *name; /* Descriptive name for the filesystem */
111 GHashTable *inodes; /* Cached inodes */
112 uint64_t next_inum; /* Next available inode for allocation */
117 /* Inode number of the root directory. */
118 #define BLUESKY_ROOT_INUM 1
120 /* Timestamp, measured in microseconds since the Unix epoch. */
121 typedef int64_t bluesky_time;
123 /* High-resolution timer, measured in nanoseconds. */
124 typedef int64_t bluesky_time_hires;
125 bluesky_time_hires bluesky_now_hires();
127 /* In-memory representation of an inode within a Blue Sky server. This
128 * corresponds roughly with information that is committed to persistent
129 * storage. Locking/refcounting rules:
130 * - To access or modify any data fields, the lock must be held. This
131 * includes file blocks.
132 * - One reference is held by the BlueSkyFS inode hash table. If that is the
133 * only reference (and the inode is unlocked), the inode is subject to
134 * dropping from the cache.
135 * - Any pending operations should hold extra references to the inode as
136 * appropriate to keep it available until the operation completes.
137 * - Locking dependency order is, when multiple locks are to be acquired, to
138 * acquire locks on parents in the filesystem tree before children.
139 * (TODO: What about rename when we acquire locks in unrelated parts of the
141 * - An inode should not be locked while the filesystem lock is already held,
142 * since some code may do an inode lookup (which acquires the filesystem
143 * lock) while a different inode is locked.
151 BlueSkyFileType type;
156 /* Rather than track an inode number and generation number, we will simply
157 * never re-use a fileid after a file is deleted. 64 bits should be enough
158 * that we don't exhaust the identifier space. */
161 /* change_count is increased with every operation which modifies the inode,
162 * and can be used to determine if cached data is still valid.
163 * change_commit is the value of change_count when the inode was last
164 * committed to stable storage. */
165 uint64_t change_count, change_commit;
167 /* Timestamp for controlling when modified data is flushed to stable
168 * storage. When an inode is first modified from a clean state, this is
169 * set to the current time. If the inode is clean, it is set to zero. */
172 /* Last access time to this inode, for controlling cache evictions. */
175 /* Additional state for tracking cache writeback status. */
176 uint64_t change_pending; /* change_count version currently being committed to storage */
178 int64_t atime; /* Microseconds since the Unix epoch */
181 int64_t ntime; /* "new time": time object was created */
183 /* File-specific fields */
187 /* Directory-specific fields */
188 GSequence *dirents; /* List of entries for READDIR */
189 GHashTable *dirhash; /* Hash table by name for LOOKUP */
190 GHashTable *dirhash_folded; /* As above, but case-folded */
191 uint64_t parent_inum; /* inode for ".."; 0 if the root directory */
193 /* Symlink-specific fields */
194 gchar *symlink_contents;
197 /* A directory entry. The name is UTF-8 and is a freshly-allocated string.
198 * Each directory entry is listed in two indices: dirents is indexed by cookie
199 * and dirhash by name. The cookie is a randomly-assigned 32-bit value, unique
200 * within the directory, that remains unchanged until the entry is deleted. It
201 * is used to provide a stable key for restarting a READDIR call. */
204 gchar *name_folded; /* Name, folded for case-insensitive lookup */
209 /* File data is divided into fixed-size blocks (except the last block which may
210 * be short?). These blocks are backed by storage in a key/value store, but
211 * may also be dirty if modifications have been made in-memory that have not
213 #define BLUESKY_BLOCK_SIZE 32768ULL
214 #define BLUESKY_MAX_FILE_SIZE (BLUESKY_BLOCK_SIZE << 24)
216 BLUESKY_BLOCK_ZERO = 0, /* Data is all zeroes, not explicitly stored */
217 BLUESKY_BLOCK_REF = 1, /* Reference to key/value store, not cached */
218 BLUESKY_BLOCK_CACHED = 2, /* Data is cached in memory, clean */
219 BLUESKY_BLOCK_DIRTY = 3, /* Data needs to be committed to store */
223 BlueSkyBlockType type;
224 gchar *ref; /* Name of data block in the backing store */
225 BlueSkyRCStr *data; /* Pointer to data in memory if cached */
228 BlueSkyFS *bluesky_init_fs(gchar *name, BlueSkyStore *store);
229 void bluesky_superblock_flush(BlueSkyFS *fs);
231 int64_t bluesky_get_current_time();
232 void bluesky_inode_update_ctime(BlueSkyInode *inode, gboolean update_mtime);
233 uint64_t bluesky_fs_alloc_inode(BlueSkyFS *fs);
234 void bluesky_init_inode(BlueSkyInode *i, BlueSkyFileType type);
235 BlueSkyInode *bluesky_new_inode(uint64_t inum, BlueSkyFS *fs, BlueSkyFileType type);
237 BlueSkyInode *bluesky_get_inode(BlueSkyFS *fs, uint64_t inum);
238 void bluesky_inode_ref(BlueSkyInode *inode);
239 void bluesky_inode_unref(BlueSkyInode *inode);
240 void bluesky_insert_inode(BlueSkyFS *fs, BlueSkyInode *inode);
242 void bluesky_dirent_destroy(gpointer dirent);
243 uint64_t bluesky_directory_lookup(BlueSkyInode *inode, gchar *name);
244 uint64_t bluesky_directory_ilookup(BlueSkyInode *inode, gchar *name);
245 BlueSkyDirent *bluesky_directory_read(BlueSkyInode *dir, uint32_t cookie);
246 gboolean bluesky_directory_insert(BlueSkyInode *dir, const gchar *name,
248 void bluesky_directory_dump(BlueSkyInode *dir);
250 void bluesky_file_truncate(BlueSkyInode *inode, uint64_t size);
251 void bluesky_file_write(BlueSkyInode *inode, uint64_t offset,
252 const char *data, gint len);
253 void bluesky_file_read(BlueSkyInode *inode, uint64_t offset,
254 char *buf, gint len);
256 void bluesky_inode_flush(BlueSkyFS *fs, BlueSkyInode *inode);
257 void bluesky_inode_fetch(BlueSkyFS *fs, uint64_t inum);
259 gint bluesky_dirent_compare(gconstpointer a, gconstpointer b,
262 void bluesky_flushd_invoke(BlueSkyFS *fs);
263 void bluesky_inode_do_sync(BlueSkyInode *inode);
265 void bluesky_debug_dump(BlueSkyFS *fs);