2 * linux/fs/ext2/ialloc.c
4 * Copyright (C) 1992, 1993, 1994, 1995
5 * Remy Card (card@masi.ibp.fr)
6 * Laboratoire MASI - Institut Blaise Pascal
7 * Universite Pierre et Marie Curie (Paris VI)
9 * BSD ufs-inspired inode and directory allocation by
10 * Stephen Tweedie (sct@dcs.ed.ac.uk), 1993
11 * Big-endian to little-endian byte-swapping/bitmaps by
12 * David S. Miller (davem@caip.rutgers.edu), 1995
15 #include <linux/quotaops.h>
16 #include <linux/sched.h>
17 #include <linux/backing-dev.h>
18 #include <linux/buffer_head.h>
19 #include <linux/random.h>
25 * ialloc.c contains the inodes allocation and deallocation routines
29 * The free inodes are managed by bitmaps. A file system contains several
30 * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap
31 * block for inodes, N blocks for the inode table and data blocks.
33 * The file system contains group descriptors which are located after the
34 * super block. Each descriptor contains the number of the bitmap block and
35 * the free blocks count in the block.
40 * Read the inode allocation bitmap for a given block_group, reading
41 * into the specified slot in the superblock's bitmap cache.
43 * Return buffer_head of bitmap on success or NULL.
45 static struct buffer_head
*
46 read_inode_bitmap(struct super_block
* sb
, unsigned long block_group
)
48 struct ext2_group_desc
*desc
;
49 struct buffer_head
*bh
= NULL
;
51 desc
= ext2_get_group_desc(sb
, block_group
, NULL
);
55 bh
= sb_bread(sb
, le32_to_cpu(desc
->bg_inode_bitmap
));
57 ext2_error(sb
, "read_inode_bitmap",
58 "Cannot read inode bitmap - "
59 "block_group = %lu, inode_bitmap = %u",
60 block_group
, le32_to_cpu(desc
->bg_inode_bitmap
));
65 static void ext2_release_inode(struct super_block
*sb
, int group
, int dir
)
67 struct ext2_group_desc
* desc
;
68 struct buffer_head
*bh
;
70 desc
= ext2_get_group_desc(sb
, group
, &bh
);
72 ext2_error(sb
, "ext2_release_inode",
73 "can't get descriptor for group %d", group
);
77 spin_lock(sb_bgl_lock(EXT2_SB(sb
), group
));
78 le16_add_cpu(&desc
->bg_free_inodes_count
, 1);
80 le16_add_cpu(&desc
->bg_used_dirs_count
, -1);
81 spin_unlock(sb_bgl_lock(EXT2_SB(sb
), group
));
83 percpu_counter_dec(&EXT2_SB(sb
)->s_dirs_counter
);
84 mark_buffer_dirty(bh
);
88 * NOTE! When we get the inode, we're the only people
89 * that have access to it, and as such there are no
90 * race conditions we have to worry about. The inode
91 * is not on the hash-lists, and it cannot be reached
92 * through the filesystem because the directory entry
93 * has been deleted earlier.
95 * HOWEVER: we must make sure that we get no aliases,
96 * which means that we have to call "clear_inode()"
97 * _before_ we mark the inode not in use in the inode
98 * bitmaps. Otherwise a newly created file might use
99 * the same inode number (not actually the same pointer
100 * though), and then we'd have two inodes sharing the
101 * same inode number and space on the harddisk.
103 void ext2_free_inode (struct inode
* inode
)
105 struct super_block
* sb
= inode
->i_sb
;
108 struct buffer_head
*bitmap_bh
;
109 unsigned long block_group
;
111 struct ext2_super_block
* es
;
114 ext2_debug ("freeing inode %lu\n", ino
);
117 * Note: we must free any quota before locking the superblock,
118 * as writing the quota to disk may need the lock as well.
120 /* Quota is already initialized in iput() */
121 dquot_free_inode(inode
);
124 es
= EXT2_SB(sb
)->s_es
;
125 is_directory
= S_ISDIR(inode
->i_mode
);
127 if (ino
< EXT2_FIRST_INO(sb
) ||
128 ino
> le32_to_cpu(es
->s_inodes_count
)) {
129 ext2_error (sb
, "ext2_free_inode",
130 "reserved or nonexistent inode %lu", ino
);
133 block_group
= (ino
- 1) / EXT2_INODES_PER_GROUP(sb
);
134 bit
= (ino
- 1) % EXT2_INODES_PER_GROUP(sb
);
135 bitmap_bh
= read_inode_bitmap(sb
, block_group
);
139 /* Ok, now we can actually update the inode bitmaps.. */
140 if (!ext2_clear_bit_atomic(sb_bgl_lock(EXT2_SB(sb
), block_group
),
141 bit
, (void *) bitmap_bh
->b_data
))
142 ext2_error (sb
, "ext2_free_inode",
143 "bit already cleared for inode %lu", ino
);
145 ext2_release_inode(sb
, block_group
, is_directory
);
146 mark_buffer_dirty(bitmap_bh
);
147 if (sb
->s_flags
& MS_SYNCHRONOUS
)
148 sync_dirty_buffer(bitmap_bh
);
154 * We perform asynchronous prereading of the new inode's inode block when
155 * we create the inode, in the expectation that the inode will be written
156 * back soon. There are two reasons:
158 * - When creating a large number of files, the async prereads will be
159 * nicely merged into large reads
160 * - When writing out a large number of inodes, we don't need to keep on
161 * stalling the writes while we read the inode block.
163 * FIXME: ext2_get_group_desc() needs to be simplified.
165 static void ext2_preread_inode(struct inode
*inode
)
167 unsigned long block_group
;
168 unsigned long offset
;
170 struct ext2_group_desc
* gdp
;
171 struct backing_dev_info
*bdi
;
173 bdi
= inode
->i_mapping
->backing_dev_info
;
174 if (bdi_read_congested(bdi
))
176 if (bdi_write_congested(bdi
))
179 block_group
= (inode
->i_ino
- 1) / EXT2_INODES_PER_GROUP(inode
->i_sb
);
180 gdp
= ext2_get_group_desc(inode
->i_sb
, block_group
, NULL
);
185 * Figure out the offset within the block group inode table
187 offset
= ((inode
->i_ino
- 1) % EXT2_INODES_PER_GROUP(inode
->i_sb
)) *
188 EXT2_INODE_SIZE(inode
->i_sb
);
189 block
= le32_to_cpu(gdp
->bg_inode_table
) +
190 (offset
>> EXT2_BLOCK_SIZE_BITS(inode
->i_sb
));
191 sb_breadahead(inode
->i_sb
, block
);
195 * There are two policies for allocating an inode. If the new inode is
196 * a directory, then a forward search is made for a block group with both
197 * free space and a low directory-to-inode ratio; if that fails, then of
198 * the groups with above-average free space, that group with the fewest
199 * directories already is chosen.
201 * For other inodes, search forward from the parent directory\'s block
202 * group to find a free inode.
204 static int find_group_dir(struct super_block
*sb
, struct inode
*parent
)
206 int ngroups
= EXT2_SB(sb
)->s_groups_count
;
207 int avefreei
= ext2_count_free_inodes(sb
) / ngroups
;
208 struct ext2_group_desc
*desc
, *best_desc
= NULL
;
209 int group
, best_group
= -1;
211 for (group
= 0; group
< ngroups
; group
++) {
212 desc
= ext2_get_group_desc (sb
, group
, NULL
);
213 if (!desc
|| !desc
->bg_free_inodes_count
)
215 if (le16_to_cpu(desc
->bg_free_inodes_count
) < avefreei
)
218 (le16_to_cpu(desc
->bg_free_blocks_count
) >
219 le16_to_cpu(best_desc
->bg_free_blocks_count
))) {
231 * Orlov's allocator for directories.
233 * We always try to spread first-level directories.
235 * If there are blockgroups with both free inodes and free blocks counts
236 * not worse than average we return one with smallest directory count.
237 * Otherwise we simply return a random group.
239 * For the rest rules look so:
241 * It's OK to put directory into a group unless
242 * it has too many directories already (max_dirs) or
243 * it has too few free inodes left (min_inodes) or
244 * it has too few free blocks left (min_blocks) or
245 * it's already running too large debt (max_debt).
246 * Parent's group is preferred, if it doesn't satisfy these
247 * conditions we search cyclically through the rest. If none
248 * of the groups look good we just look for a group with more
249 * free inodes than average (starting at parent's group).
251 * Debt is incremented each time we allocate a directory and decremented
252 * when we allocate an inode, within 0--255.
255 #define INODE_COST 64
256 #define BLOCK_COST 256
258 static int find_group_orlov(struct super_block
*sb
, struct inode
*parent
)
260 int parent_group
= EXT2_I(parent
)->i_block_group
;
261 struct ext2_sb_info
*sbi
= EXT2_SB(sb
);
262 struct ext2_super_block
*es
= sbi
->s_es
;
263 int ngroups
= sbi
->s_groups_count
;
264 int inodes_per_group
= EXT2_INODES_PER_GROUP(sb
);
271 int max_debt
, max_dirs
, min_blocks
, min_inodes
;
273 struct ext2_group_desc
*desc
;
275 freei
= percpu_counter_read_positive(&sbi
->s_freeinodes_counter
);
276 avefreei
= freei
/ ngroups
;
277 free_blocks
= percpu_counter_read_positive(&sbi
->s_freeblocks_counter
);
278 avefreeb
= free_blocks
/ ngroups
;
279 ndirs
= percpu_counter_read_positive(&sbi
->s_dirs_counter
);
281 if ((parent
== sb
->s_root
->d_inode
) ||
282 (EXT2_I(parent
)->i_flags
& EXT2_TOPDIR_FL
)) {
283 struct ext2_group_desc
*best_desc
= NULL
;
284 int best_ndir
= inodes_per_group
;
287 group
= prandom_u32();
288 parent_group
= (unsigned)group
% ngroups
;
289 for (i
= 0; i
< ngroups
; i
++) {
290 group
= (parent_group
+ i
) % ngroups
;
291 desc
= ext2_get_group_desc (sb
, group
, NULL
);
292 if (!desc
|| !desc
->bg_free_inodes_count
)
294 if (le16_to_cpu(desc
->bg_used_dirs_count
) >= best_ndir
)
296 if (le16_to_cpu(desc
->bg_free_inodes_count
) < avefreei
)
298 if (le16_to_cpu(desc
->bg_free_blocks_count
) < avefreeb
)
301 best_ndir
= le16_to_cpu(desc
->bg_used_dirs_count
);
304 if (best_group
>= 0) {
313 ndirs
= 1; /* percpu_counters are approximate... */
315 blocks_per_dir
= (le32_to_cpu(es
->s_blocks_count
)-free_blocks
) / ndirs
;
317 max_dirs
= ndirs
/ ngroups
+ inodes_per_group
/ 16;
318 min_inodes
= avefreei
- inodes_per_group
/ 4;
319 min_blocks
= avefreeb
- EXT2_BLOCKS_PER_GROUP(sb
) / 4;
321 max_debt
= EXT2_BLOCKS_PER_GROUP(sb
) / max(blocks_per_dir
, BLOCK_COST
);
322 if (max_debt
* INODE_COST
> inodes_per_group
)
323 max_debt
= inodes_per_group
/ INODE_COST
;
329 for (i
= 0; i
< ngroups
; i
++) {
330 group
= (parent_group
+ i
) % ngroups
;
331 desc
= ext2_get_group_desc (sb
, group
, NULL
);
332 if (!desc
|| !desc
->bg_free_inodes_count
)
334 if (sbi
->s_debts
[group
] >= max_debt
)
336 if (le16_to_cpu(desc
->bg_used_dirs_count
) >= max_dirs
)
338 if (le16_to_cpu(desc
->bg_free_inodes_count
) < min_inodes
)
340 if (le16_to_cpu(desc
->bg_free_blocks_count
) < min_blocks
)
346 for (i
= 0; i
< ngroups
; i
++) {
347 group
= (parent_group
+ i
) % ngroups
;
348 desc
= ext2_get_group_desc (sb
, group
, NULL
);
349 if (!desc
|| !desc
->bg_free_inodes_count
)
351 if (le16_to_cpu(desc
->bg_free_inodes_count
) >= avefreei
)
357 * The free-inodes counter is approximate, and for really small
358 * filesystems the above test can fail to find any blockgroups
370 static int find_group_other(struct super_block
*sb
, struct inode
*parent
)
372 int parent_group
= EXT2_I(parent
)->i_block_group
;
373 int ngroups
= EXT2_SB(sb
)->s_groups_count
;
374 struct ext2_group_desc
*desc
;
378 * Try to place the inode in its parent directory
380 group
= parent_group
;
381 desc
= ext2_get_group_desc (sb
, group
, NULL
);
382 if (desc
&& le16_to_cpu(desc
->bg_free_inodes_count
) &&
383 le16_to_cpu(desc
->bg_free_blocks_count
))
387 * We're going to place this inode in a different blockgroup from its
388 * parent. We want to cause files in a common directory to all land in
389 * the same blockgroup. But we want files which are in a different
390 * directory which shares a blockgroup with our parent to land in a
391 * different blockgroup.
393 * So add our directory's i_ino into the starting point for the hash.
395 group
= (group
+ parent
->i_ino
) % ngroups
;
398 * Use a quadratic hash to find a group with a free inode and some
401 for (i
= 1; i
< ngroups
; i
<<= 1) {
403 if (group
>= ngroups
)
405 desc
= ext2_get_group_desc (sb
, group
, NULL
);
406 if (desc
&& le16_to_cpu(desc
->bg_free_inodes_count
) &&
407 le16_to_cpu(desc
->bg_free_blocks_count
))
412 * That failed: try linear search for a free inode, even if that group
413 * has no free blocks.
415 group
= parent_group
;
416 for (i
= 0; i
< ngroups
; i
++) {
417 if (++group
>= ngroups
)
419 desc
= ext2_get_group_desc (sb
, group
, NULL
);
420 if (desc
&& le16_to_cpu(desc
->bg_free_inodes_count
))
430 struct inode
*ext2_new_inode(struct inode
*dir
, umode_t mode
,
431 const struct qstr
*qstr
)
433 struct super_block
*sb
;
434 struct buffer_head
*bitmap_bh
= NULL
;
435 struct buffer_head
*bh2
;
438 struct inode
* inode
;
439 struct ext2_group_desc
*gdp
;
440 struct ext2_super_block
*es
;
441 struct ext2_inode_info
*ei
;
442 struct ext2_sb_info
*sbi
;
446 inode
= new_inode(sb
);
448 return ERR_PTR(-ENOMEM
);
454 if (test_opt(sb
, OLDALLOC
))
455 group
= find_group_dir(sb
, dir
);
457 group
= find_group_orlov(sb
, dir
);
459 group
= find_group_other(sb
, dir
);
466 for (i
= 0; i
< sbi
->s_groups_count
; i
++) {
467 gdp
= ext2_get_group_desc(sb
, group
, &bh2
);
469 bitmap_bh
= read_inode_bitmap(sb
, group
);
476 repeat_in_this_group
:
477 ino
= ext2_find_next_zero_bit((unsigned long *)bitmap_bh
->b_data
,
478 EXT2_INODES_PER_GROUP(sb
), ino
);
479 if (ino
>= EXT2_INODES_PER_GROUP(sb
)) {
481 * Rare race: find_group_xx() decided that there were
482 * free inodes in this group, but by the time we tried
483 * to allocate one, they're all gone. This can also
484 * occur because the counters which find_group_orlov()
485 * uses are approximate. So just go and search the
488 if (++group
== sbi
->s_groups_count
)
492 if (ext2_set_bit_atomic(sb_bgl_lock(sbi
, group
),
493 ino
, bitmap_bh
->b_data
)) {
494 /* we lost this inode */
495 if (++ino
>= EXT2_INODES_PER_GROUP(sb
)) {
496 /* this group is exhausted, try next group */
497 if (++group
== sbi
->s_groups_count
)
501 /* try to find free inode in the same group */
502 goto repeat_in_this_group
;
508 * Scanned all blockgroups.
513 mark_buffer_dirty(bitmap_bh
);
514 if (sb
->s_flags
& MS_SYNCHRONOUS
)
515 sync_dirty_buffer(bitmap_bh
);
518 ino
+= group
* EXT2_INODES_PER_GROUP(sb
) + 1;
519 if (ino
< EXT2_FIRST_INO(sb
) || ino
> le32_to_cpu(es
->s_inodes_count
)) {
520 ext2_error (sb
, "ext2_new_inode",
521 "reserved inode or inode > inodes count - "
522 "block_group = %d,inode=%lu", group
,
523 (unsigned long) ino
);
528 percpu_counter_add(&sbi
->s_freeinodes_counter
, -1);
530 percpu_counter_inc(&sbi
->s_dirs_counter
);
532 spin_lock(sb_bgl_lock(sbi
, group
));
533 le16_add_cpu(&gdp
->bg_free_inodes_count
, -1);
535 if (sbi
->s_debts
[group
] < 255)
536 sbi
->s_debts
[group
]++;
537 le16_add_cpu(&gdp
->bg_used_dirs_count
, 1);
539 if (sbi
->s_debts
[group
])
540 sbi
->s_debts
[group
]--;
542 spin_unlock(sb_bgl_lock(sbi
, group
));
544 mark_buffer_dirty(bh2
);
545 if (test_opt(sb
, GRPID
)) {
546 inode
->i_mode
= mode
;
547 inode
->i_uid
= current_fsuid();
548 inode
->i_gid
= dir
->i_gid
;
550 inode_init_owner(inode
, dir
, mode
);
554 inode
->i_mtime
= inode
->i_atime
= inode
->i_ctime
= CURRENT_TIME_SEC
;
555 memset(ei
->i_data
, 0, sizeof(ei
->i_data
));
557 ext2_mask_flags(mode
, EXT2_I(dir
)->i_flags
& EXT2_FL_INHERITED
);
564 ei
->i_block_alloc_info
= NULL
;
565 ei
->i_block_group
= group
;
566 ei
->i_dir_start_lookup
= 0;
567 ei
->i_state
= EXT2_STATE_NEW
;
568 ext2_set_inode_flags(inode
);
569 spin_lock(&sbi
->s_next_gen_lock
);
570 inode
->i_generation
= sbi
->s_next_generation
++;
571 spin_unlock(&sbi
->s_next_gen_lock
);
572 if (insert_inode_locked(inode
) < 0) {
573 ext2_error(sb
, "ext2_new_inode",
574 "inode number already in use - inode=%lu",
575 (unsigned long) ino
);
580 dquot_initialize(inode
);
581 err
= dquot_alloc_inode(inode
);
585 err
= ext2_init_acl(inode
, dir
);
589 err
= ext2_init_security(inode
, dir
, qstr
);
593 mark_inode_dirty(inode
);
594 ext2_debug("allocating inode %lu\n", inode
->i_ino
);
595 ext2_preread_inode(inode
);
599 dquot_free_inode(inode
);
603 inode
->i_flags
|= S_NOQUOTA
;
605 unlock_new_inode(inode
);
610 make_bad_inode(inode
);
615 unsigned long ext2_count_free_inodes (struct super_block
* sb
)
617 struct ext2_group_desc
*desc
;
618 unsigned long desc_count
= 0;
622 struct ext2_super_block
*es
;
623 unsigned long bitmap_count
= 0;
624 struct buffer_head
*bitmap_bh
= NULL
;
626 es
= EXT2_SB(sb
)->s_es
;
627 for (i
= 0; i
< EXT2_SB(sb
)->s_groups_count
; i
++) {
630 desc
= ext2_get_group_desc (sb
, i
, NULL
);
633 desc_count
+= le16_to_cpu(desc
->bg_free_inodes_count
);
635 bitmap_bh
= read_inode_bitmap(sb
, i
);
639 x
= ext2_count_free(bitmap_bh
, EXT2_INODES_PER_GROUP(sb
) / 8);
640 printk("group %d: stored = %d, counted = %u\n",
641 i
, le16_to_cpu(desc
->bg_free_inodes_count
), x
);
645 printk("ext2_count_free_inodes: stored = %lu, computed = %lu, %lu\n",
647 percpu_counter_read(&EXT2_SB(sb
)->s_freeinodes_counter
),
648 desc_count
, bitmap_count
);
651 for (i
= 0; i
< EXT2_SB(sb
)->s_groups_count
; i
++) {
652 desc
= ext2_get_group_desc (sb
, i
, NULL
);
655 desc_count
+= le16_to_cpu(desc
->bg_free_inodes_count
);
661 /* Called at mount-time, super-block is locked */
662 unsigned long ext2_count_dirs (struct super_block
* sb
)
664 unsigned long count
= 0;
667 for (i
= 0; i
< EXT2_SB(sb
)->s_groups_count
; i
++) {
668 struct ext2_group_desc
*gdp
= ext2_get_group_desc (sb
, i
, NULL
);
671 count
+= le16_to_cpu(gdp
->bg_used_dirs_count
);