blob: fc7684554b1a9042f87c3918f669861a475ddae3 [file] [log] [blame]
Jaegeuk Kim0a8165d2012-11-29 13:28:09 +09001/*
Jaegeuk Kim39a53e02012-11-28 13:37:31 +09002 * fs/f2fs/node.h
3 *
4 * Copyright (c) 2012 Samsung Electronics Co., Ltd.
5 * http://www.samsung.com/
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11/* start node id of a node block dedicated to the given node id */
12#define START_NID(nid) ((nid / NAT_ENTRY_PER_BLOCK) * NAT_ENTRY_PER_BLOCK)
13
14/* node block offset on the NAT area dedicated to the given start node id */
15#define NAT_BLOCK_OFFSET(start_nid) (start_nid / NAT_ENTRY_PER_BLOCK)
16
Chao Yuea1a29a02015-10-12 17:08:48 +080017/* # of pages to perform synchronous readahead before building free nids */
Jaegeuk Kimad4edb82016-06-16 16:41:49 -070018#define FREE_NID_PAGES 8
19#define MAX_FREE_NIDS (NAT_ENTRY_PER_BLOCK * FREE_NID_PAGES)
Jaegeuk Kim39a53e02012-11-28 13:37:31 +090020
Jaegeuk Kimad4edb82016-06-16 16:41:49 -070021#define DEF_RA_NID_PAGES 0 /* # of nid pages to be readaheaded */
Chao Yuea1a29a02015-10-12 17:08:48 +080022
Jaegeuk Kim39a53e02012-11-28 13:37:31 +090023/* maximum readahead size for node during getting data blocks */
24#define MAX_RA_NODE 128
25
Jaegeuk Kimcdfc41c2014-03-19 13:31:37 +090026/* control the memory footprint threshold (10MB per 1GB ram) */
Jaegeuk Kim29710bc2016-06-02 15:26:27 -070027#define DEF_RAM_THRESHOLD 1
Jaegeuk Kimcdfc41c2014-03-19 13:31:37 +090028
Chao Yu7d768d22016-01-18 18:31:18 +080029/* control dirty nats ratio threshold (default: 10% over max nid count) */
30#define DEF_DIRTY_NAT_RATIO_THRESHOLD 10
Jaegeuk Kime589c2c2016-06-02 15:24:24 -070031/* control total # of nats */
32#define DEF_NAT_CACHE_THRESHOLD 100000
Chao Yu7d768d22016-01-18 18:31:18 +080033
Jaegeuk Kim39a53e02012-11-28 13:37:31 +090034/* vector size for gang look-up from nat cache that consists of radix tree */
35#define NATVEC_SIZE 64
Jaegeuk Kim7aed0d42015-01-07 10:47:57 -080036#define SETVEC_SIZE 32
Jaegeuk Kim39a53e02012-11-28 13:37:31 +090037
Jaegeuk Kim56ae6742013-03-31 12:47:20 +090038/* return value for read_node_page */
39#define LOCKED_PAGE 1
40
Chao Yu5c27f4e2014-12-18 17:37:21 +080041/* For flag in struct node_info */
42enum {
43 IS_CHECKPOINTED, /* is it checkpointed before? */
44 HAS_FSYNCED_INODE, /* is the inode fsynced before? */
45 HAS_LAST_FSYNC, /* has the latest node fsync mark? */
46 IS_DIRTY, /* this nat entry is dirty? */
47};
48
Jaegeuk Kim39a53e02012-11-28 13:37:31 +090049/*
50 * For node information
51 */
52struct node_info {
53 nid_t nid; /* node id */
54 nid_t ino; /* inode number of the node's owner */
55 block_t blk_addr; /* block address of the node */
56 unsigned char version; /* version of the node */
Chao Yu5c27f4e2014-12-18 17:37:21 +080057 unsigned char flag; /* for node information bits */
Jaegeuk Kim7ef35e32014-09-15 12:07:13 -070058};
59
Jaegeuk Kim39a53e02012-11-28 13:37:31 +090060struct nat_entry {
61 struct list_head list; /* for clean or dirty nat list */
Jaegeuk Kim39a53e02012-11-28 13:37:31 +090062 struct node_info ni; /* in-memory node information */
63};
64
65#define nat_get_nid(nat) (nat->ni.nid)
66#define nat_set_nid(nat, n) (nat->ni.nid = n)
67#define nat_get_blkaddr(nat) (nat->ni.blk_addr)
68#define nat_set_blkaddr(nat, b) (nat->ni.blk_addr = b)
69#define nat_get_ino(nat) (nat->ni.ino)
70#define nat_set_ino(nat, i) (nat->ni.ino = i)
71#define nat_get_version(nat) (nat->ni.version)
72#define nat_set_version(nat, v) (nat->ni.version = v)
73
Jaegeuk Kim39a53e02012-11-28 13:37:31 +090074#define inc_node_version(version) (++version)
75
Chao Yu5c27f4e2014-12-18 17:37:21 +080076static inline void copy_node_info(struct node_info *dst,
77 struct node_info *src)
78{
79 dst->nid = src->nid;
80 dst->ino = src->ino;
81 dst->blk_addr = src->blk_addr;
82 dst->version = src->version;
83 /* should not copy flag here */
84}
85
Jaegeuk Kim7ef35e32014-09-15 12:07:13 -070086static inline void set_nat_flag(struct nat_entry *ne,
87 unsigned int type, bool set)
88{
89 unsigned char mask = 0x01 << type;
90 if (set)
Chao Yu5c27f4e2014-12-18 17:37:21 +080091 ne->ni.flag |= mask;
Jaegeuk Kim7ef35e32014-09-15 12:07:13 -070092 else
Chao Yu5c27f4e2014-12-18 17:37:21 +080093 ne->ni.flag &= ~mask;
Jaegeuk Kim7ef35e32014-09-15 12:07:13 -070094}
95
96static inline bool get_nat_flag(struct nat_entry *ne, unsigned int type)
97{
98 unsigned char mask = 0x01 << type;
Chao Yu5c27f4e2014-12-18 17:37:21 +080099 return ne->ni.flag & mask;
Jaegeuk Kim7ef35e32014-09-15 12:07:13 -0700100}
101
Jaegeuk Kim88bd02c2014-09-15 14:50:48 -0700102static inline void nat_reset_flag(struct nat_entry *ne)
103{
104 /* these states can be set only after checkpoint was done */
105 set_nat_flag(ne, IS_CHECKPOINTED, true);
106 set_nat_flag(ne, HAS_FSYNCED_INODE, false);
107 set_nat_flag(ne, HAS_LAST_FSYNC, true);
108}
109
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900110static inline void node_info_from_raw_nat(struct node_info *ni,
111 struct f2fs_nat_entry *raw_ne)
112{
113 ni->ino = le32_to_cpu(raw_ne->ino);
114 ni->blk_addr = le32_to_cpu(raw_ne->block_addr);
115 ni->version = raw_ne->version;
116}
117
Chao Yu94dac222014-04-17 10:51:05 +0800118static inline void raw_nat_from_node_info(struct f2fs_nat_entry *raw_ne,
119 struct node_info *ni)
120{
121 raw_ne->ino = cpu_to_le32(ni->ino);
122 raw_ne->block_addr = cpu_to_le32(ni->blk_addr);
123 raw_ne->version = ni->version;
124}
125
Chao Yu7d768d22016-01-18 18:31:18 +0800126static inline bool excess_dirty_nats(struct f2fs_sb_info *sbi)
127{
128 return NM_I(sbi)->dirty_nat_cnt >= NM_I(sbi)->max_nid *
Chao Yu2304cb02016-01-18 18:32:58 +0800129 NM_I(sbi)->dirty_nats_ratio / 100;
Chao Yu7d768d22016-01-18 18:31:18 +0800130}
131
Jaegeuk Kime589c2c2016-06-02 15:24:24 -0700132static inline bool excess_cached_nats(struct f2fs_sb_info *sbi)
133{
134 return NM_I(sbi)->nat_cnt >= DEF_NAT_CACHE_THRESHOLD;
135}
136
Jaegeuk Kim6fb03f32014-04-16 10:47:06 +0900137enum mem_type {
Jaegeuk Kimcdfc41c2014-03-19 13:31:37 +0900138 FREE_NIDS, /* indicates the free nid list */
Jaegeuk Kim6fb03f32014-04-16 10:47:06 +0900139 NAT_ENTRIES, /* indicates the cached nat entry */
Jaegeuk Kima1257022015-10-08 10:40:07 -0700140 DIRTY_DENTS, /* indicates dirty dentry pages */
Jaegeuk Kime5e7ea32014-11-06 15:24:46 -0800141 INO_ENTRIES, /* indicates inode entries */
Chao Yu13054c52015-02-05 17:52:58 +0800142 EXTENT_CACHE, /* indicates extent cache */
Jaegeuk Kim1e843712014-12-09 06:08:59 -0800143 BASE_CHECK, /* check kernel status */
Jaegeuk Kimcdfc41c2014-03-19 13:31:37 +0900144};
145
Chao Yuaec71382014-06-24 09:18:20 +0800146struct nat_entry_set {
Jaegeuk Kim309cc2b2014-09-22 11:40:48 -0700147 struct list_head set_list; /* link with other nat sets */
Chao Yuaec71382014-06-24 09:18:20 +0800148 struct list_head entry_list; /* link with dirty nat entries */
Jaegeuk Kim309cc2b2014-09-22 11:40:48 -0700149 nid_t set; /* set number*/
Chao Yuaec71382014-06-24 09:18:20 +0800150 unsigned int entry_cnt; /* the # of nat entries in set */
151};
152
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900153/*
154 * For free nid mangement
155 */
156enum nid_state {
157 NID_NEW, /* newly added to free nid list */
158 NID_ALLOC /* it is allocated */
159};
160
161struct free_nid {
162 struct list_head list; /* for free node id list */
163 nid_t nid; /* node id */
164 int state; /* in use or not: NID_NEW or NID_ALLOC */
165};
166
Jaegeuk Kim120c2cb2014-10-03 15:12:42 -0700167static inline void next_free_nid(struct f2fs_sb_info *sbi, nid_t *nid)
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900168{
169 struct f2fs_nm_info *nm_i = NM_I(sbi);
170 struct free_nid *fnid;
171
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900172 spin_lock(&nm_i->free_nid_list_lock);
Huang Yingc6e48932014-09-12 19:21:11 +0800173 if (nm_i->fcnt <= 0) {
174 spin_unlock(&nm_i->free_nid_list_lock);
Jaegeuk Kim120c2cb2014-10-03 15:12:42 -0700175 return;
Huang Yingc6e48932014-09-12 19:21:11 +0800176 }
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900177 fnid = list_entry(nm_i->free_nid_list.next, struct free_nid, list);
178 *nid = fnid->nid;
179 spin_unlock(&nm_i->free_nid_list_lock);
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900180}
181
182/*
183 * inline functions
184 */
185static inline void get_nat_bitmap(struct f2fs_sb_info *sbi, void *addr)
186{
187 struct f2fs_nm_info *nm_i = NM_I(sbi);
188 memcpy(addr, nm_i->nat_bitmap, nm_i->bitmap_size);
189}
190
191static inline pgoff_t current_nat_addr(struct f2fs_sb_info *sbi, nid_t start)
192{
193 struct f2fs_nm_info *nm_i = NM_I(sbi);
194 pgoff_t block_off;
195 pgoff_t block_addr;
196 int seg_off;
197
198 block_off = NAT_BLOCK_OFFSET(start);
199 seg_off = block_off >> sbi->log_blocks_per_seg;
200
201 block_addr = (pgoff_t)(nm_i->nat_blkaddr +
202 (seg_off << sbi->log_blocks_per_seg << 1) +
Chao Yu3519e3f2015-12-01 11:56:52 +0800203 (block_off & (sbi->blocks_per_seg - 1)));
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900204
205 if (f2fs_test_bit(block_off, nm_i->nat_bitmap))
206 block_addr += sbi->blocks_per_seg;
207
208 return block_addr;
209}
210
211static inline pgoff_t next_nat_addr(struct f2fs_sb_info *sbi,
212 pgoff_t block_addr)
213{
214 struct f2fs_nm_info *nm_i = NM_I(sbi);
215
216 block_addr -= nm_i->nat_blkaddr;
217 if ((block_addr >> sbi->log_blocks_per_seg) % 2)
218 block_addr -= sbi->blocks_per_seg;
219 else
220 block_addr += sbi->blocks_per_seg;
221
222 return block_addr + nm_i->nat_blkaddr;
223}
224
225static inline void set_to_next_nat(struct f2fs_nm_info *nm_i, nid_t start_nid)
226{
227 unsigned int block_off = NAT_BLOCK_OFFSET(start_nid);
228
Gu Zhengc6ac4c02014-10-20 17:45:50 +0800229 f2fs_change_bit(block_off, nm_i->nat_bitmap);
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900230}
231
232static inline void fill_node_footer(struct page *page, nid_t nid,
233 nid_t ino, unsigned int ofs, bool reset)
234{
Gu Zheng45590712013-07-15 17:57:38 +0800235 struct f2fs_node *rn = F2FS_NODE(page);
Jaegeuk Kim09eb4832014-12-23 16:26:31 -0800236 unsigned int old_flag = 0;
237
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900238 if (reset)
239 memset(rn, 0, sizeof(*rn));
Jaegeuk Kim09eb4832014-12-23 16:26:31 -0800240 else
241 old_flag = le32_to_cpu(rn->footer.flag);
242
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900243 rn->footer.nid = cpu_to_le32(nid);
244 rn->footer.ino = cpu_to_le32(ino);
Jaegeuk Kim09eb4832014-12-23 16:26:31 -0800245
246 /* should remain old flag bits such as COLD_BIT_SHIFT */
247 rn->footer.flag = cpu_to_le32((ofs << OFFSET_BIT_SHIFT) |
248 (old_flag & OFFSET_BIT_MASK));
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900249}
250
251static inline void copy_node_footer(struct page *dst, struct page *src)
252{
Gu Zheng45590712013-07-15 17:57:38 +0800253 struct f2fs_node *src_rn = F2FS_NODE(src);
254 struct f2fs_node *dst_rn = F2FS_NODE(dst);
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900255 memcpy(&dst_rn->footer, &src_rn->footer, sizeof(struct node_footer));
256}
257
258static inline void fill_node_footer_blkaddr(struct page *page, block_t blkaddr)
259{
Jaegeuk Kim40813632014-09-02 15:31:18 -0700260 struct f2fs_checkpoint *ckpt = F2FS_CKPT(F2FS_P_SB(page));
Gu Zheng45590712013-07-15 17:57:38 +0800261 struct f2fs_node *rn = F2FS_NODE(page);
262
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900263 rn->footer.cp_ver = ckpt->checkpoint_ver;
Jaegeuk Kim25ca9232012-11-28 16:12:41 +0900264 rn->footer.next_blkaddr = cpu_to_le32(blkaddr);
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900265}
266
267static inline nid_t ino_of_node(struct page *node_page)
268{
Gu Zheng45590712013-07-15 17:57:38 +0800269 struct f2fs_node *rn = F2FS_NODE(node_page);
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900270 return le32_to_cpu(rn->footer.ino);
271}
272
273static inline nid_t nid_of_node(struct page *node_page)
274{
Gu Zheng45590712013-07-15 17:57:38 +0800275 struct f2fs_node *rn = F2FS_NODE(node_page);
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900276 return le32_to_cpu(rn->footer.nid);
277}
278
279static inline unsigned int ofs_of_node(struct page *node_page)
280{
Gu Zheng45590712013-07-15 17:57:38 +0800281 struct f2fs_node *rn = F2FS_NODE(node_page);
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900282 unsigned flag = le32_to_cpu(rn->footer.flag);
283 return flag >> OFFSET_BIT_SHIFT;
284}
285
286static inline unsigned long long cpver_of_node(struct page *node_page)
287{
Gu Zheng45590712013-07-15 17:57:38 +0800288 struct f2fs_node *rn = F2FS_NODE(node_page);
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900289 return le64_to_cpu(rn->footer.cp_ver);
290}
291
292static inline block_t next_blkaddr_of_node(struct page *node_page)
293{
Gu Zheng45590712013-07-15 17:57:38 +0800294 struct f2fs_node *rn = F2FS_NODE(node_page);
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900295 return le32_to_cpu(rn->footer.next_blkaddr);
296}
297
298/*
299 * f2fs assigns the following node offsets described as (num).
300 * N = NIDS_PER_BLOCK
301 *
302 * Inode block (0)
303 * |- direct node (1)
304 * |- direct node (2)
305 * |- indirect node (3)
306 * | `- direct node (4 => 4 + N - 1)
307 * |- indirect node (4 + N)
308 * | `- direct node (5 + N => 5 + 2N - 1)
309 * `- double indirect node (5 + 2N)
310 * `- indirect node (6 + 2N)
Chao Yu4f4124d2013-12-21 18:02:14 +0800311 * `- direct node
312 * ......
313 * `- indirect node ((6 + 2N) + x(N + 1))
314 * `- direct node
315 * ......
316 * `- indirect node ((6 + 2N) + (N - 1)(N + 1))
317 * `- direct node
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900318 */
319static inline bool IS_DNODE(struct page *node_page)
320{
321 unsigned int ofs = ofs_of_node(node_page);
Jaegeuk Kimdbe6a5f2013-08-09 08:14:06 +0900322
Chao Yu4bc8e9b2014-03-17 16:35:06 +0800323 if (f2fs_has_xattr_block(ofs))
Jaegeuk Kimdbe6a5f2013-08-09 08:14:06 +0900324 return false;
325
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900326 if (ofs == 3 || ofs == 4 + NIDS_PER_BLOCK ||
327 ofs == 5 + 2 * NIDS_PER_BLOCK)
328 return false;
329 if (ofs >= 6 + 2 * NIDS_PER_BLOCK) {
330 ofs -= 6 + 2 * NIDS_PER_BLOCK;
Zhihui Zhang33151012013-04-07 12:57:04 -0400331 if (!((long int)ofs % (NIDS_PER_BLOCK + 1)))
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900332 return false;
333 }
334 return true;
335}
336
Jaegeuk Kim12719ae2016-01-07 13:23:12 -0800337static inline int set_nid(struct page *p, int off, nid_t nid, bool i)
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900338{
Gu Zheng45590712013-07-15 17:57:38 +0800339 struct f2fs_node *rn = F2FS_NODE(p);
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900340
Jaegeuk Kimfec1d652016-01-20 23:43:51 +0800341 f2fs_wait_on_page_writeback(p, NODE, true);
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900342
343 if (i)
344 rn->i.i_nid[off - NODE_DIR1_BLOCK] = cpu_to_le32(nid);
345 else
346 rn->in.nid[off] = cpu_to_le32(nid);
Jaegeuk Kim12719ae2016-01-07 13:23:12 -0800347 return set_page_dirty(p);
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900348}
349
350static inline nid_t get_nid(struct page *p, int off, bool i)
351{
Gu Zheng45590712013-07-15 17:57:38 +0800352 struct f2fs_node *rn = F2FS_NODE(p);
353
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900354 if (i)
355 return le32_to_cpu(rn->i.i_nid[off - NODE_DIR1_BLOCK]);
356 return le32_to_cpu(rn->in.nid[off]);
357}
358
359/*
360 * Coldness identification:
361 * - Mark cold files in f2fs_inode_info
362 * - Mark cold node blocks in their node footer
363 * - Mark cold data pages in page cache
364 */
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900365static inline int is_cold_data(struct page *page)
366{
367 return PageChecked(page);
368}
369
370static inline void set_cold_data(struct page *page)
371{
372 SetPageChecked(page);
373}
374
375static inline void clear_cold_data(struct page *page)
376{
377 ClearPageChecked(page);
378}
379
Namjae Jeona06a2412013-05-23 22:58:40 +0900380static inline int is_node(struct page *page, int type)
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900381{
Gu Zheng45590712013-07-15 17:57:38 +0800382 struct f2fs_node *rn = F2FS_NODE(page);
Namjae Jeona06a2412013-05-23 22:58:40 +0900383 return le32_to_cpu(rn->footer.flag) & (1 << type);
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900384}
385
Namjae Jeona06a2412013-05-23 22:58:40 +0900386#define is_cold_node(page) is_node(page, COLD_BIT_SHIFT)
387#define is_fsync_dnode(page) is_node(page, FSYNC_BIT_SHIFT)
388#define is_dent_dnode(page) is_node(page, DENT_BIT_SHIFT)
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900389
Jaegeuk Kim2049d4f2016-01-25 05:57:05 -0800390static inline int is_inline_node(struct page *page)
391{
392 return PageChecked(page);
393}
394
395static inline void set_inline_node(struct page *page)
396{
397 SetPageChecked(page);
398}
399
400static inline void clear_inline_node(struct page *page)
401{
402 ClearPageChecked(page);
403}
404
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900405static inline void set_cold_node(struct inode *inode, struct page *page)
406{
Gu Zheng45590712013-07-15 17:57:38 +0800407 struct f2fs_node *rn = F2FS_NODE(page);
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900408 unsigned int flag = le32_to_cpu(rn->footer.flag);
409
410 if (S_ISDIR(inode->i_mode))
411 flag &= ~(0x1 << COLD_BIT_SHIFT);
412 else
413 flag |= (0x1 << COLD_BIT_SHIFT);
414 rn->footer.flag = cpu_to_le32(flag);
415}
416
Namjae Jeona06a2412013-05-23 22:58:40 +0900417static inline void set_mark(struct page *page, int mark, int type)
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900418{
Gu Zheng45590712013-07-15 17:57:38 +0800419 struct f2fs_node *rn = F2FS_NODE(page);
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900420 unsigned int flag = le32_to_cpu(rn->footer.flag);
421 if (mark)
Namjae Jeona06a2412013-05-23 22:58:40 +0900422 flag |= (0x1 << type);
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900423 else
Namjae Jeona06a2412013-05-23 22:58:40 +0900424 flag &= ~(0x1 << type);
Jaegeuk Kim39a53e02012-11-28 13:37:31 +0900425 rn->footer.flag = cpu_to_le32(flag);
426}
Namjae Jeona06a2412013-05-23 22:58:40 +0900427#define set_dentry_mark(page, mark) set_mark(page, mark, DENT_BIT_SHIFT)
428#define set_fsync_mark(page, mark) set_mark(page, mark, FSYNC_BIT_SHIFT)