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 /* Reference-counted blocks of memory, used for passing data in and out of
16 * storage backends and in other places. */
23 BlueSkyRCStr *bluesky_string_new(gpointer data, gsize len);
24 void bluesky_string_ref(BlueSkyRCStr *string);
25 void bluesky_string_unref(BlueSkyRCStr *string);
26 BlueSkyRCStr *bluesky_string_dup(BlueSkyRCStr *string);
28 /* File types. The numeric values are chosen to match with those used in
32 BLUESKY_DIRECTORY = 2,
34 BLUESKY_CHARACTER = 4,
40 /* Filesystem state. Each filesystem which is exported is represented by a
41 * single bluesky_fs structure in memory. */
45 gchar *name; /* Descriptive name for the filesystem */
46 GHashTable *inodes; /* Cached inodes */
47 uint64_t next_inum; /* Next available inode for allocation */
50 /* Inode number of the root directory. */
51 #define BLUESKY_ROOT_INUM 1
53 /* Timestamp, measured in microseconds since the Unix epoch. */
54 typedef int64_t bluesky_time;
56 /* In-memory representation of an inode within a Blue Sky server. This
57 * corresponds roughly with information that is committed to persistent
60 gint refcnt; /* May be accessed atomically without lock */
68 /* Rather than track an inode number and generation number, we will simply
69 * never re-use a fileid after a file is deleted. 64 bits should be enough
70 * that we don't exhaust the identifier space. */
73 uint64_t change_count; /* Incremented each with each change made */
74 int64_t atime; /* Microseconds since the Unix epoch */
77 int64_t ntime; /* "new time": time object was created */
79 /* File-specific fields */
83 /* Directory-specific fields */
84 GSequence *dirents; /* List of entries for READDIR */
85 GHashTable *dirhash; /* Hash table by name for LOOKUP */
86 uint64_t parent_inum; /* inode for ".."; 0 if the root directory */
89 /* A directory entry. The name is UTF-8 and is a freshly-allocated string.
90 * Each directory entry is listed in two indices: dirents is indexed by cookie
91 * and dirhash by name. The cookie is a randomly-assigned 32-bit value, unique
92 * within the directory, that remains unchanged until the entry is deleted. It
93 * is used to provide a stable key for restarting a READDIR call. */
100 /* File data is divided into fixed-size blocks (except the last block which may
101 * be short?). These blocks are backed by storage in a key/value store, but
102 * may also be dirty if modifications have been made in-memory that have not
104 #define BLUESKY_BLOCK_SIZE 32768ULL
105 #define BLUESKY_MAX_FILE_SIZE (BLUESKY_BLOCK_SIZE << 24)
107 BLUESKY_BLOCK_ZERO = 0, /* Data is all zeroes, not explicitly stored */
108 BLUESKY_BLOCK_REF = 1, /* Reference to key/value store, not cached */
109 BLUESKY_BLOCK_CACHED = 2, /* Data is cached in memory, clean */
110 BLUESKY_BLOCK_DIRTY = 3, /* Data needs to be committed to store */
114 BlueSkyBlockType type;
115 gchar *ref; /* Name of data block in the backing store */
116 gchar *data; /* Pointer to data in memory */
119 BlueSkyFS *bluesky_new_fs(gchar *name);
120 int64_t bluesky_get_current_time();
121 void bluesky_inode_update_ctime(BlueSkyInode *inode, gboolean update_mtime);
122 uint64_t bluesky_fs_alloc_inode(BlueSkyFS *fs);
123 BlueSkyInode *bluesky_new_inode(uint64_t inum, BlueSkyFileType type);
125 BlueSkyInode *bluesky_get_inode(BlueSkyFS *fs, uint64_t inum);
126 void bluesky_insert_inode(BlueSkyFS *fs, BlueSkyInode *inode);
128 void bluesky_dirent_destroy(gpointer dirent);
129 uint64_t bluesky_directory_hash(gchar *name);
130 uint64_t bluesky_directory_lookup(BlueSkyInode *inode, gchar *name);
131 gboolean bluesky_directory_insert(BlueSkyInode *dir, gchar *name,
133 void bluesky_directory_dump(BlueSkyInode *dir);
135 void bluesky_block_touch(BlueSkyInode *inode, uint64_t i);
136 void bluesky_block_flush(BlueSkyBlock *block);
137 void bluesky_file_truncate(BlueSkyInode *inode, uint64_t size);
138 void bluesky_file_write(BlueSkyInode *inode, uint64_t offset,
139 const char *data, gint len);
140 void bluesky_file_read(BlueSkyInode *inode, uint64_t offset,
141 char *buf, gint len);