1/*
2 * Copyright 2000 by Hans Reiser, licensing governed by reiserfs/README
3 */
4
5#include <linux/string.h>
6#include <linux/time.h>
7#include <linux/uuid.h>
8#include "reiserfs.h"
9
10/* find where objectid map starts */
11#define objectid_map(s,rs) (old_format_only (s) ? \
12                         (__le32 *)((struct reiserfs_super_block_v1 *)(rs) + 1) :\
13			 (__le32 *)((rs) + 1))
14
15#ifdef CONFIG_REISERFS_CHECK
16
17static void check_objectid_map(struct super_block *s, __le32 * map)
18{
19	if (le32_to_cpu(map[0]) != 1)
20		reiserfs_panic(s, "vs-15010", "map corrupted: %lx",
21			       (long unsigned int)le32_to_cpu(map[0]));
22
23	/* FIXME: add something else here */
24}
25
26#else
27static void check_objectid_map(struct super_block *s, __le32 * map)
28{;
29}
30#endif
31
32/*
33 * When we allocate objectids we allocate the first unused objectid.
34 * Each sequence of objectids in use (the odd sequences) is followed
35 * by a sequence of objectids not in use (the even sequences).  We
36 * only need to record the last objectid in each of these sequences
37 * (both the odd and even sequences) in order to fully define the
38 * boundaries of the sequences.  A consequence of allocating the first
39 * objectid not in use is that under most conditions this scheme is
40 * extremely compact.  The exception is immediately after a sequence
41 * of operations which deletes a large number of objects of
42 * non-sequential objectids, and even then it will become compact
43 * again as soon as more objects are created.  Note that many
44 * interesting optimizations of layout could result from complicating
45 * objectid assignment, but we have deferred making them for now.
46 */
47
48/* get unique object identifier */
49__u32 reiserfs_get_unused_objectid(struct reiserfs_transaction_handle *th)
50{
51	struct super_block *s = th->t_super;
52	struct reiserfs_super_block *rs = SB_DISK_SUPER_BLOCK(s);
53	__le32 *map = objectid_map(s, rs);
54	__u32 unused_objectid;
55
56	BUG_ON(!th->t_trans_id);
57
58	check_objectid_map(s, map);
59
60	reiserfs_prepare_for_journal(s, SB_BUFFER_WITH_SB(s), 1);
61	/* comment needed -Hans */
62	unused_objectid = le32_to_cpu(map[1]);
63	if (unused_objectid == U32_MAX) {
64		reiserfs_warning(s, "reiserfs-15100", "no more object ids");
65		reiserfs_restore_prepared_buffer(s, SB_BUFFER_WITH_SB(s));
66		return 0;
67	}
68
69	/*
70	 * This incrementation allocates the first unused objectid. That
71	 * is to say, the first entry on the objectid map is the first
72	 * unused objectid, and by incrementing it we use it.  See below
73	 * where we check to see if we eliminated a sequence of unused
74	 * objectids....
75	 */
76	map[1] = cpu_to_le32(unused_objectid + 1);
77
78	/*
79	 * Now we check to see if we eliminated the last remaining member of
80	 * the first even sequence (and can eliminate the sequence by
81	 * eliminating its last objectid from oids), and can collapse the
82	 * first two odd sequences into one sequence.  If so, then the net
83	 * result is to eliminate a pair of objectids from oids.  We do this
84	 * by shifting the entire map to the left.
85	 */
86	if (sb_oid_cursize(rs) > 2 && map[1] == map[2]) {
87		memmove(map + 1, map + 3,
88			(sb_oid_cursize(rs) - 3) * sizeof(__u32));
89		set_sb_oid_cursize(rs, sb_oid_cursize(rs) - 2);
90	}
91
92	journal_mark_dirty(th, SB_BUFFER_WITH_SB(s));
93	return unused_objectid;
94}
95
96/* makes object identifier unused */
97void reiserfs_release_objectid(struct reiserfs_transaction_handle *th,
98			       __u32 objectid_to_release)
99{
100	struct super_block *s = th->t_super;
101	struct reiserfs_super_block *rs = SB_DISK_SUPER_BLOCK(s);
102	__le32 *map = objectid_map(s, rs);
103	int i = 0;
104
105	BUG_ON(!th->t_trans_id);
106	/*return; */
107	check_objectid_map(s, map);
108
109	reiserfs_prepare_for_journal(s, SB_BUFFER_WITH_SB(s), 1);
110	journal_mark_dirty(th, SB_BUFFER_WITH_SB(s));
111
112	/*
113	 * start at the beginning of the objectid map (i = 0) and go to
114	 * the end of it (i = disk_sb->s_oid_cursize).  Linear search is
115	 * what we use, though it is possible that binary search would be
116	 * more efficient after performing lots of deletions (which is
117	 * when oids is large.)  We only check even i's.
118	 */
119	while (i < sb_oid_cursize(rs)) {
120		if (objectid_to_release == le32_to_cpu(map[i])) {
121			/* This incrementation unallocates the objectid. */
122			le32_add_cpu(&map[i], 1);
123
124			/*
125			 * Did we unallocate the last member of an
126			 * odd sequence, and can shrink oids?
127			 */
128			if (map[i] == map[i + 1]) {
129				/* shrink objectid map */
130				memmove(map + i, map + i + 2,
131					(sb_oid_cursize(rs) - i -
132					 2) * sizeof(__u32));
133				set_sb_oid_cursize(rs, sb_oid_cursize(rs) - 2);
134
135				RFALSE(sb_oid_cursize(rs) < 2 ||
136				       sb_oid_cursize(rs) > sb_oid_maxsize(rs),
137				       "vs-15005: objectid map corrupted cur_size == %d (max == %d)",
138				       sb_oid_cursize(rs), sb_oid_maxsize(rs));
139			}
140			return;
141		}
142
143		if (objectid_to_release > le32_to_cpu(map[i]) &&
144		    objectid_to_release < le32_to_cpu(map[i + 1])) {
145			/* size of objectid map is not changed */
146			if (objectid_to_release + 1 == le32_to_cpu(map[i + 1])) {
147				le32_add_cpu(&map[i + 1], -1);
148				return;
149			}
150
151			/*
152			 * JDM comparing two little-endian values for
153			 * equality -- safe
154			 */
155			/*
156			 * objectid map must be expanded, but
157			 * there is no space
158			 */
159			if (sb_oid_cursize(rs) == sb_oid_maxsize(rs)) {
160				PROC_INFO_INC(s, leaked_oid);
161				return;
162			}
163
164			/* expand the objectid map */
165			memmove(map + i + 3, map + i + 1,
166				(sb_oid_cursize(rs) - i - 1) * sizeof(__u32));
167			map[i + 1] = cpu_to_le32(objectid_to_release);
168			map[i + 2] = cpu_to_le32(objectid_to_release + 1);
169			set_sb_oid_cursize(rs, sb_oid_cursize(rs) + 2);
170			return;
171		}
172		i += 2;
173	}
174
175	reiserfs_error(s, "vs-15011", "tried to free free object id (%lu)",
176		       (long unsigned)objectid_to_release);
177}
178
179int reiserfs_convert_objectid_map_v1(struct super_block *s)
180{
181	struct reiserfs_super_block *disk_sb = SB_DISK_SUPER_BLOCK(s);
182	int cur_size = sb_oid_cursize(disk_sb);
183	int new_size = (s->s_blocksize - SB_SIZE) / sizeof(__u32) / 2 * 2;
184	int old_max = sb_oid_maxsize(disk_sb);
185	struct reiserfs_super_block_v1 *disk_sb_v1;
186	__le32 *objectid_map;
187	int i;
188
189	disk_sb_v1 =
190	    (struct reiserfs_super_block_v1 *)(SB_BUFFER_WITH_SB(s)->b_data);
191	objectid_map = (__le32 *) (disk_sb_v1 + 1);
192
193	if (cur_size > new_size) {
194		/*
195		 * mark everyone used that was listed as free at
196		 * the end of the objectid map
197		 */
198		objectid_map[new_size - 1] = objectid_map[cur_size - 1];
199		set_sb_oid_cursize(disk_sb, new_size);
200	}
201	/* move the smaller objectid map past the end of the new super */
202	for (i = new_size - 1; i >= 0; i--) {
203		objectid_map[i + (old_max - new_size)] = objectid_map[i];
204	}
205
206	/* set the max size so we don't overflow later */
207	set_sb_oid_maxsize(disk_sb, new_size);
208
209	/* Zero out label and generate random UUID */
210	memset(disk_sb->s_label, 0, sizeof(disk_sb->s_label));
211	generate_random_uuid(disk_sb->s_uuid);
212
213	/* finally, zero out the unused chunk of the new super */
214	memset(disk_sb->s_unused, 0, sizeof(disk_sb->s_unused));
215	return 0;
216}
217