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: handling of directories. */
17 void bluesky_dirent_destroy(gpointer data)
19 BlueSkyDirent *dirent = (BlueSkyDirent *)data;
21 g_free(dirent->name_folded);
25 gint bluesky_dirent_compare(gconstpointer a, gconstpointer b,
28 uint32_t hash1 = ((const BlueSkyDirent *)a)->cookie;
29 uint32_t hash2 = ((const BlueSkyDirent *)b)->cookie;
33 else if (hash1 > hash2)
39 /* Perform a lookup for a file name within a directory. Returns the inode
40 * number if found, or 0 if not (0 is never a valid inode number). Should be
41 * called with the inode lock already held. */
42 uint64_t bluesky_directory_lookup(BlueSkyInode *inode, gchar *name)
44 g_return_val_if_fail(inode->type == BLUESKY_DIRECTORY, 0);
45 g_return_val_if_fail(inode->dirhash != NULL, 0);
47 BlueSkyDirent *d = g_hash_table_lookup(inode->dirhash, name);
54 /* Case-insensitive lookup. */
55 uint64_t bluesky_directory_ilookup(BlueSkyInode *inode, gchar *name)
57 g_return_val_if_fail(inode->type == BLUESKY_DIRECTORY, 0);
58 g_return_val_if_fail(inode->dirhash_folded != NULL, 0);
60 name = bluesky_lowercase(name);
61 BlueSkyDirent *d = g_hash_table_lookup(inode->dirhash_folded, name);
70 /* Insert a new entry into a directory. Should be called with the inode lock
72 gboolean bluesky_directory_insert(BlueSkyInode *dir, gchar *name, uint64_t inum)
74 g_return_val_if_fail(dir->type == BLUESKY_DIRECTORY, FALSE);
76 /* Check that no entry with the given name already exists. */
77 if (g_hash_table_lookup(dir->dirhash, name) != NULL)
80 BlueSkyDirent *d = g_new(BlueSkyDirent, 1);
81 d->name = g_strdup(name);
82 d->name_folded = bluesky_lowercase(name);
85 GSequence *dirents = dir->dirents;
87 /* Pick an unused cookie value for the directory at random. Restrict
88 * ourselves to positive 32-bit values (even if treated as signed), and
89 * keep the first four slots free. */
92 d->cookie = g_random_int() & 0x7fffffff;
93 } while (d->cookie < 4);
95 /* If the directory is empty, we can't possibly have a collision, so
96 * just go with the first key chosen. */
97 if (g_sequence_get_length(dirents) == 0)
100 /* Otherwise, try looking up the generated cookie. If we do not find a
101 * match, we can use this cookie value, otherwise we need to generate a
102 * new one and try again. Because of the check above for an empty
103 * directory, we know that the lookup will return something so no need
104 * to worry about NULL. */
105 GSequenceIter *i = g_sequence_search(dir->dirents, d,
106 bluesky_dirent_compare, NULL);
107 i = g_sequence_iter_prev(i);
108 if (((BlueSkyDirent *)g_sequence_get(i))->cookie != d->cookie)
112 /* Add the directory entry to both indices. */
113 g_sequence_insert_sorted(dirents, d, bluesky_dirent_compare, NULL);
114 g_hash_table_insert(dir->dirhash, d->name, d);
115 g_hash_table_insert(dir->dirhash_folded, d->name_folded, d);
117 bluesky_inode_update_ctime(dir, 1);
118 bluesky_inode_flush(dir->fs, dir);
123 /* Remove an from a directory. Should be called with the inode lock already
125 gboolean bluesky_directory_remove(BlueSkyInode *dir, gchar *name)
127 g_return_val_if_fail(dir->type == BLUESKY_DIRECTORY, FALSE);
129 BlueSkyDirent *d = g_hash_table_lookup(dir->dirhash, name);
134 g_hash_table_remove(dir->dirhash, d->name);
135 g_hash_table_remove(dir->dirhash_folded, d->name_folded);
137 GSequenceIter *i = g_sequence_search(dir->dirents, d,
138 bluesky_dirent_compare, NULL);
139 i = g_sequence_iter_prev(i);
141 /* Assertion check, this ought to succeed */
142 g_return_val_if_fail(g_sequence_get(i) == d, FALSE);
144 g_sequence_remove(i);
146 bluesky_inode_update_ctime(dir, 1);
147 bluesky_inode_flush(dir->fs, dir);
152 /* Dump the contents of a directory to stdout. Debugging only. */
153 void bluesky_directory_dump(BlueSkyInode *dir)
155 g_print("Directory dump:\n");
157 GSequenceIter *i = g_sequence_get_begin_iter(dir->dirents);
159 while (!g_sequence_iter_is_end(i)) {
160 BlueSkyDirent *d = g_sequence_get(i);
161 g_print(" 0x%08x [inum=%"PRIu64"] %s\n",
162 d->cookie, d->inum, d->name);
163 i = g_sequence_iter_next(i);