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 /* Maximum number of threads to use in any particular thread pool, or -1 for no
42 extern int bluesky_max_threads;
44 /* BlueSky status and error codes. Various frontends should translate these to
45 * the appropriate error code for whatever protocol they implement. */
47 BSTATUS_OK = 0, /* No error */
48 BSTATUS_IOERR, /* I/O error of some form */
49 BSTATUS_NOENT, /* File does not exist */
52 void bluesky_init(void);
54 gchar *bluesky_lowercase(const gchar *s);
56 /* Reference-counted blocks of memory, used for passing data in and out of
57 * storage backends and in other places. */
64 BlueSkyRCStr *bluesky_string_new(gpointer data, gsize len);
65 BlueSkyRCStr *bluesky_string_new_from_gstring(GString *s);
66 void bluesky_string_ref(BlueSkyRCStr *string);
67 void bluesky_string_unref(BlueSkyRCStr *string);
68 BlueSkyRCStr *bluesky_string_dup(BlueSkyRCStr *string);
69 void bluesky_string_resize(BlueSkyRCStr *string, gsize len);
71 /* Cryptographic operations. */
72 #define CRYPTO_BLOCK_SIZE 16 /* 128-bit AES */
73 #define CRYPTO_KEY_SIZE 16
75 void bluesky_crypt_init();
76 void bluesky_crypt_hash_key(const char *keystr, uint8_t *out);
77 void bluesky_crypt_random_bytes(guchar *buf, gint len);
78 BlueSkyRCStr *bluesky_crypt_encrypt(BlueSkyRCStr *in, const uint8_t *key);
79 BlueSkyRCStr *bluesky_crypt_decrypt(BlueSkyRCStr *in, const uint8_t *key);
81 /* Storage interface. This presents a key-value store abstraction, and can
82 * have multiple implementations: in-memory, on-disk, in-cloud. */
84 typedef struct _BlueSkyStore BlueSkyStore;
86 void bluesky_store_init();
87 BlueSkyStore *bluesky_store_new(const gchar *type);
88 void bluesky_store_free(BlueSkyStore *store);
89 BlueSkyRCStr *bluesky_store_get(BlueSkyStore *store, const gchar *key);
90 void bluesky_store_put(BlueSkyStore *store,
91 const gchar *key, BlueSkyRCStr *val);
93 /* File types. The numeric values are chosen to match with those used in
97 BLUESKY_DIRECTORY = 2,
99 BLUESKY_CHARACTER = 4,
104 /* Special types used only internally. */
105 BLUESKY_PENDING = 0, /* Inode being loaded; type not yet determined */
106 BLUESKY_INVALID = -1, /* Inode is invalid (failed to load) */
109 /* Filesystem state. Each filesystem which is exported is represented by a
110 * single bluesky_fs structure in memory. */
114 gchar *name; /* Descriptive name for the filesystem */
115 GHashTable *inodes; /* Cached inodes */
116 uint64_t next_inum; /* Next available inode for allocation */
120 /* Accounting for memory used for caches. Space is measured in blocks, not
121 * bytes. We track both total data in the caches and dirty data (total
122 * data includes dirty data). Updates to these variables must be made
124 gint cache_total, cache_dirty;
126 /* Linked list of inodes, sorted by access/modification times for cache
127 * management. Editing these lists is protected by the filesystem lock; to
128 * avoid deadlock do not attempt to take any other locks while the FS lock
129 * is held for list editing purposes. Items at the head of the list are
130 * most recently accessed/modified. */
131 GList dirty_list, accessed_list;
134 /* Inode number of the root directory. */
135 #define BLUESKY_ROOT_INUM 1
137 /* Timestamp, measured in microseconds since the Unix epoch. */
138 typedef int64_t bluesky_time;
140 /* High-resolution timer, measured in nanoseconds. */
141 typedef int64_t bluesky_time_hires;
142 bluesky_time_hires bluesky_now_hires();
144 /* In-memory representation of an inode within a Blue Sky server. This
145 * corresponds roughly with information that is committed to persistent
146 * storage. Locking/refcounting rules:
147 * - To access or modify any data fields, the lock must be held. This
148 * includes file blocks.
149 * - One reference is held by the BlueSkyFS inode hash table. If that is the
150 * only reference (and the inode is unlocked), the inode is subject to
151 * dropping from the cache.
152 * - Any pending operations should hold extra references to the inode as
153 * appropriate to keep it available until the operation completes.
154 * - Locking dependency order is, when multiple locks are to be acquired, to
155 * acquire locks on parents in the filesystem tree before children.
156 * (TODO: What about rename when we acquire locks in unrelated parts of the
158 * - An inode should not be locked while the filesystem lock is already held,
159 * since some code may do an inode lookup (which acquires the filesystem
160 * lock) while a different inode is locked.
168 BlueSkyFileType type;
173 /* Rather than track an inode number and generation number, we will simply
174 * never re-use a fileid after a file is deleted. 64 bits should be enough
175 * that we don't exhaust the identifier space. */
178 /* change_count is increased with every operation which modifies the inode,
179 * and can be used to determine if cached data is still valid.
180 * change_commit is the value of change_count when the inode was last
181 * committed to stable storage. */
182 uint64_t change_count, change_commit;
184 /* Timestamp for controlling when modified data is flushed to stable
185 * storage. When an inode is first modified from a clean state, this is
186 * set to the current time. If the inode is clean, it is set to zero. */
189 /* Last access time to this inode, for controlling cache evictions. */
192 /* Additional state for tracking cache writeback status. */
193 uint64_t change_pending; /* change_count version currently being committed to storage */
195 /* Pointers to the linked-list elements for this inode in the accessed and
196 * dirty linked lists. We re-use the GList structure, using ->next to
197 * point to the head of the list and ->prev to point to the tail. The data
198 * element is unused. */
199 GList *accessed_list, *dirty_list;
201 int64_t atime; /* Microseconds since the Unix epoch */
204 int64_t ntime; /* "new time": time object was created */
206 /* File-specific fields */
210 /* Directory-specific fields */
211 GSequence *dirents; /* List of entries for READDIR */
212 GHashTable *dirhash; /* Hash table by name for LOOKUP */
213 GHashTable *dirhash_folded; /* As above, but case-folded */
214 uint64_t parent_inum; /* inode for ".."; 0 if the root directory */
216 /* Symlink-specific fields */
217 gchar *symlink_contents;
220 /* A directory entry. The name is UTF-8 and is a freshly-allocated string.
221 * Each directory entry is listed in two indices: dirents is indexed by cookie
222 * and dirhash by name. The cookie is a randomly-assigned 32-bit value, unique
223 * within the directory, that remains unchanged until the entry is deleted. It
224 * is used to provide a stable key for restarting a READDIR call. */
227 gchar *name_folded; /* Name, folded for case-insensitive lookup */
232 /* File data is divided into fixed-size blocks (except the last block which may
233 * be short?). These blocks are backed by storage in a key/value store, but
234 * may also be dirty if modifications have been made in-memory that have not
236 #define BLUESKY_BLOCK_SIZE 32768ULL
237 #define BLUESKY_MAX_FILE_SIZE (BLUESKY_BLOCK_SIZE << 24)
239 BLUESKY_BLOCK_ZERO = 0, /* Data is all zeroes, not explicitly stored */
240 BLUESKY_BLOCK_REF = 1, /* Reference to key/value store, not cached */
241 BLUESKY_BLOCK_CACHED = 2, /* Data is cached in memory, clean */
242 BLUESKY_BLOCK_DIRTY = 3, /* Data needs to be committed to store */
246 BlueSkyBlockType type;
247 gchar *ref; /* Name of data block in the backing store */
248 BlueSkyRCStr *data; /* Pointer to data in memory if cached */
251 BlueSkyFS *bluesky_init_fs(gchar *name, BlueSkyStore *store);
252 void bluesky_superblock_flush(BlueSkyFS *fs);
254 int64_t bluesky_get_current_time();
255 void bluesky_inode_update_ctime(BlueSkyInode *inode, gboolean update_mtime);
256 uint64_t bluesky_fs_alloc_inode(BlueSkyFS *fs);
257 void bluesky_init_inode(BlueSkyInode *i, BlueSkyFileType type);
258 BlueSkyInode *bluesky_new_inode(uint64_t inum, BlueSkyFS *fs, BlueSkyFileType type);
260 BlueSkyInode *bluesky_get_inode(BlueSkyFS *fs, uint64_t inum);
261 void bluesky_inode_ref(BlueSkyInode *inode);
262 void bluesky_inode_unref(BlueSkyInode *inode);
263 void bluesky_insert_inode(BlueSkyFS *fs, BlueSkyInode *inode);
265 void bluesky_dirent_destroy(gpointer dirent);
266 uint64_t bluesky_directory_lookup(BlueSkyInode *inode, gchar *name);
267 uint64_t bluesky_directory_ilookup(BlueSkyInode *inode, gchar *name);
268 BlueSkyDirent *bluesky_directory_read(BlueSkyInode *dir, uint32_t cookie);
269 gboolean bluesky_directory_insert(BlueSkyInode *dir, const gchar *name,
271 void bluesky_directory_dump(BlueSkyInode *dir);
273 void bluesky_file_truncate(BlueSkyInode *inode, uint64_t size);
274 void bluesky_file_write(BlueSkyInode *inode, uint64_t offset,
275 const char *data, gint len);
276 void bluesky_file_read(BlueSkyInode *inode, uint64_t offset,
277 char *buf, gint len);
279 void bluesky_inode_flush(BlueSkyFS *fs, BlueSkyInode *inode);
280 void bluesky_inode_fetch(BlueSkyFS *fs, uint64_t inum);
282 gint bluesky_dirent_compare(gconstpointer a, gconstpointer b,
285 void bluesky_flushd_invoke(BlueSkyFS *fs);
286 void bluesky_inode_do_sync(BlueSkyInode *inode);
288 void bluesky_debug_dump(BlueSkyFS *fs);