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 /* File types. The numeric values are chosen to match with those used in
19 BLUESKY_DIRECTORY = 2,
21 BLUESKY_CHARACTER = 4,
27 /* Filesystem state. Each filesystem which is exported is represented by a
28 * single bluesky_fs structure in memory. */
32 gchar *name; /* Descriptive name for the filesystem */
33 GHashTable *inodes; /* Cached inodes */
34 uint64_t next_inum; /* Next available inode for allocation */
37 /* Inode number of the root directory. */
38 #define BLUESKY_ROOT_INUM 1
40 /* Timestamp, measured in microseconds since the Unix epoch. */
41 typedef int64_t bluesky_time;
43 /* In-memory representation of an inode within a Blue Sky server. This
44 * corresponds roughly with information that is committed to persistent
47 gint refcnt; /* May be accessed atomically without lock */
55 /* Rather than track an inode number and generation number, we will simply
56 * never re-use a fileid after a file is deleted. 64 bits should be enough
57 * that we don't exhaust the identifier space. */
60 uint64_t change_count; /* Incremented each with each change made */
61 int64_t atime; /* Microseconds since the Unix epoch */
64 int64_t ntime; /* "new time": time object was created */
66 /* File-specific fields */
70 /* Directory-specific fields */
71 GSequence *dirents; /* List of entries for READDIR */
72 GHashTable *dirhash; /* Hash table by name for LOOKUP */
73 uint64_t parent_inum; /* inode for ".."; 0 if the root directory */
76 /* A directory entry. The name is UTF-8 and is a freshly-allocated string.
77 * Each directory entry is listed in two indices: dirents is indexed by cookie
78 * and dirhash by name. The cookie is a randomly-assigned 32-bit value, unique
79 * within the directory, that remains unchanged until the entry is deleted. It
80 * is used to provide a stable key for restarting a READDIR call. */
87 /* File data is divided into fixed-size blocks (except the last block which may
88 * be short?). These blocks are backed by storage in a key/value store, but
89 * may also be dirty if modifications have been made in-memory that have not
91 #define BLUESKY_BLOCK_SIZE 32768ULL
92 #define BLUESKY_MAX_FILE_SIZE (BLUESKY_BLOCK_SIZE << 24)
94 BLUESKY_BLOCK_ZERO = 0, /* Data is all zeroes, not explicitly stored */
95 BLUESKY_BLOCK_REF = 1, /* Reference to key/value store, not cached */
96 BLUESKY_BLOCK_CACHED = 2, /* Data is cached in memory, clean */
97 BLUESKY_BLOCK_DIRTY = 3, /* Data needs to be committed to store */
101 BlueSkyBlockType type;
102 gchar *ref; /* Name of data block in the backing store */
103 gchar *data; /* Pointer to data in memory */
106 BlueSkyFS *bluesky_new_fs(gchar *name);
107 int64_t bluesky_get_current_time();
108 void bluesky_inode_update_ctime(BlueSkyInode *inode, gboolean update_mtime);
109 uint64_t bluesky_fs_alloc_inode(BlueSkyFS *fs);
110 BlueSkyInode *bluesky_new_inode(uint64_t inum, BlueSkyFileType type);
112 BlueSkyInode *bluesky_get_inode(BlueSkyFS *fs, uint64_t inum);
113 void bluesky_insert_inode(BlueSkyFS *fs, BlueSkyInode *inode);
115 void bluesky_dirent_destroy(gpointer dirent);
116 uint64_t bluesky_directory_hash(gchar *name);
117 uint64_t bluesky_directory_lookup(BlueSkyInode *inode, gchar *name);
118 gboolean bluesky_directory_insert(BlueSkyInode *dir, gchar *name,
120 void bluesky_directory_dump(BlueSkyInode *dir);
122 void bluesky_file_truncate(BlueSkyInode *inode, uint64_t size);