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1 // SPDX-License-Identifier: GPL-2.0
3 * linux/fs/ext2/ialloc.c
5 * Copyright (C) 1992, 1993, 1994, 1995
6 * Remy Card (card@masi.ibp.fr)
7 * Laboratoire MASI - Institut Blaise Pascal
8 * Universite Pierre et Marie Curie (Paris VI)
10 * BSD ufs-inspired inode and directory allocation by
11 * Stephen Tweedie (sct@dcs.ed.ac.uk), 1993
12 * Big-endian to little-endian byte-swapping/bitmaps by
13 * David S. Miller (davem@caip.rutgers.edu), 1995
16 #include <linux/quotaops.h>
17 #include <linux/sched.h>
18 #include <linux/backing-dev.h>
19 #include <linux/buffer_head.h>
20 #include <linux/random.h>
26 * ialloc.c contains the inodes allocation and deallocation routines
30 * The free inodes are managed by bitmaps. A file system contains several
31 * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap
32 * block for inodes, N blocks for the inode table and data blocks.
34 * The file system contains group descriptors which are located after the
35 * super block. Each descriptor contains the number of the bitmap block and
36 * the free blocks count in the block.
41 * Read the inode allocation bitmap for a given block_group, reading
42 * into the specified slot in the superblock's bitmap cache.
44 * Return buffer_head of bitmap on success or NULL.
46 static struct buffer_head
*
47 read_inode_bitmap(struct super_block
* sb
, unsigned long block_group
)
49 struct ext2_group_desc
*desc
;
50 struct buffer_head
*bh
= NULL
;
52 desc
= ext2_get_group_desc(sb
, block_group
, NULL
);
56 bh
= sb_bread(sb
, le32_to_cpu(desc
->bg_inode_bitmap
));
58 ext2_error(sb
, "read_inode_bitmap",
59 "Cannot read inode bitmap - "
60 "block_group = %lu, inode_bitmap = %u",
61 block_group
, le32_to_cpu(desc
->bg_inode_bitmap
));
66 static void ext2_release_inode(struct super_block
*sb
, int group
, int dir
)
68 struct ext2_group_desc
* desc
;
69 struct buffer_head
*bh
;
71 desc
= ext2_get_group_desc(sb
, group
, &bh
);
73 ext2_error(sb
, "ext2_release_inode",
74 "can't get descriptor for group %d", group
);
78 spin_lock(sb_bgl_lock(EXT2_SB(sb
), group
));
79 le16_add_cpu(&desc
->bg_free_inodes_count
, 1);
81 le16_add_cpu(&desc
->bg_used_dirs_count
, -1);
82 spin_unlock(sb_bgl_lock(EXT2_SB(sb
), group
));
84 percpu_counter_dec(&EXT2_SB(sb
)->s_dirs_counter
);
85 mark_buffer_dirty(bh
);
89 * NOTE! When we get the inode, we're the only people
90 * that have access to it, and as such there are no
91 * race conditions we have to worry about. The inode
92 * is not on the hash-lists, and it cannot be reached
93 * through the filesystem because the directory entry
94 * has been deleted earlier.
96 * HOWEVER: we must make sure that we get no aliases,
97 * which means that we have to call "clear_inode()"
98 * _before_ we mark the inode not in use in the inode
99 * bitmaps. Otherwise a newly created file might use
100 * the same inode number (not actually the same pointer
101 * though), and then we'd have two inodes sharing the
102 * same inode number and space on the harddisk.
104 void ext2_free_inode (struct inode
* inode
)
106 struct super_block
* sb
= inode
->i_sb
;
109 struct buffer_head
*bitmap_bh
;
110 unsigned long block_group
;
112 struct ext2_super_block
* es
;
115 ext2_debug ("freeing inode %lu\n", ino
);
118 * Note: we must free any quota before locking the superblock,
119 * as writing the quota to disk may need the lock as well.
121 /* Quota is already initialized in iput() */
122 dquot_free_inode(inode
);
125 es
= EXT2_SB(sb
)->s_es
;
126 is_directory
= S_ISDIR(inode
->i_mode
);
128 if (ino
< EXT2_FIRST_INO(sb
) ||
129 ino
> le32_to_cpu(es
->s_inodes_count
)) {
130 ext2_error (sb
, "ext2_free_inode",
131 "reserved or nonexistent inode %lu", ino
);
134 block_group
= (ino
- 1) / EXT2_INODES_PER_GROUP(sb
);
135 bit
= (ino
- 1) % EXT2_INODES_PER_GROUP(sb
);
136 bitmap_bh
= read_inode_bitmap(sb
, block_group
);
140 /* Ok, now we can actually update the inode bitmaps.. */
141 if (!ext2_clear_bit_atomic(sb_bgl_lock(EXT2_SB(sb
), block_group
),
142 bit
, (void *) bitmap_bh
->b_data
))
143 ext2_error (sb
, "ext2_free_inode",
144 "bit already cleared for inode %lu", ino
);
146 ext2_release_inode(sb
, block_group
, is_directory
);
147 mark_buffer_dirty(bitmap_bh
);
148 if (sb
->s_flags
& SB_SYNCHRONOUS
)
149 sync_dirty_buffer(bitmap_bh
);
155 * We perform asynchronous prereading of the new inode's inode block when
156 * we create the inode, in the expectation that the inode will be written
157 * back soon. There are two reasons:
159 * - When creating a large number of files, the async prereads will be
160 * nicely merged into large reads
161 * - When writing out a large number of inodes, we don't need to keep on
162 * stalling the writes while we read the inode block.
164 * FIXME: ext2_get_group_desc() needs to be simplified.
166 static void ext2_preread_inode(struct inode
*inode
)
168 unsigned long block_group
;
169 unsigned long offset
;
171 struct ext2_group_desc
* gdp
;
172 struct backing_dev_info
*bdi
;
174 bdi
= inode_to_bdi(inode
);
175 if (bdi_read_congested(bdi
))
177 if (bdi_write_congested(bdi
))
180 block_group
= (inode
->i_ino
- 1) / EXT2_INODES_PER_GROUP(inode
->i_sb
);
181 gdp
= ext2_get_group_desc(inode
->i_sb
, block_group
, NULL
);
186 * Figure out the offset within the block group inode table
188 offset
= ((inode
->i_ino
- 1) % EXT2_INODES_PER_GROUP(inode
->i_sb
)) *
189 EXT2_INODE_SIZE(inode
->i_sb
);
190 block
= le32_to_cpu(gdp
->bg_inode_table
) +
191 (offset
>> EXT2_BLOCK_SIZE_BITS(inode
->i_sb
));
192 sb_breadahead(inode
->i_sb
, block
);
196 * There are two policies for allocating an inode. If the new inode is
197 * a directory, then a forward search is made for a block group with both
198 * free space and a low directory-to-inode ratio; if that fails, then of
199 * the groups with above-average free space, that group with the fewest
200 * directories already is chosen.
202 * For other inodes, search forward from the parent directory\'s block
203 * group to find a free inode.
205 static int find_group_dir(struct super_block
*sb
, struct inode
*parent
)
207 int ngroups
= EXT2_SB(sb
)->s_groups_count
;
208 int avefreei
= ext2_count_free_inodes(sb
) / ngroups
;
209 struct ext2_group_desc
*desc
, *best_desc
= NULL
;
210 int group
, best_group
= -1;
212 for (group
= 0; group
< ngroups
; group
++) {
213 desc
= ext2_get_group_desc (sb
, group
, NULL
);
214 if (!desc
|| !desc
->bg_free_inodes_count
)
216 if (le16_to_cpu(desc
->bg_free_inodes_count
) < avefreei
)
219 (le16_to_cpu(desc
->bg_free_blocks_count
) >
220 le16_to_cpu(best_desc
->bg_free_blocks_count
))) {
232 * Orlov's allocator for directories.
234 * We always try to spread first-level directories.
236 * If there are blockgroups with both free inodes and free blocks counts
237 * not worse than average we return one with smallest directory count.
238 * Otherwise we simply return a random group.
240 * For the rest rules look so:
242 * It's OK to put directory into a group unless
243 * it has too many directories already (max_dirs) or
244 * it has too few free inodes left (min_inodes) or
245 * it has too few free blocks left (min_blocks) or
246 * it's already running too large debt (max_debt).
247 * Parent's group is preferred, if it doesn't satisfy these
248 * conditions we search cyclically through the rest. If none
249 * of the groups look good we just look for a group with more
250 * free inodes than average (starting at parent's group).
252 * Debt is incremented each time we allocate a directory and decremented
253 * when we allocate an inode, within 0--255.
256 #define INODE_COST 64
257 #define BLOCK_COST 256
259 static int find_group_orlov(struct super_block
*sb
, struct inode
*parent
)
261 int parent_group
= EXT2_I(parent
)->i_block_group
;
262 struct ext2_sb_info
*sbi
= EXT2_SB(sb
);
263 struct ext2_super_block
*es
= sbi
->s_es
;
264 int ngroups
= sbi
->s_groups_count
;
265 int inodes_per_group
= EXT2_INODES_PER_GROUP(sb
);
272 int max_debt
, max_dirs
, min_blocks
, min_inodes
;
274 struct ext2_group_desc
*desc
;
276 freei
= percpu_counter_read_positive(&sbi
->s_freeinodes_counter
);
277 avefreei
= freei
/ ngroups
;
278 free_blocks
= percpu_counter_read_positive(&sbi
->s_freeblocks_counter
);
279 avefreeb
= free_blocks
/ ngroups
;
280 ndirs
= percpu_counter_read_positive(&sbi
->s_dirs_counter
);
282 if ((parent
== d_inode(sb
->s_root
)) ||
283 (EXT2_I(parent
)->i_flags
& EXT2_TOPDIR_FL
)) {
284 struct ext2_group_desc
*best_desc
= NULL
;
285 int best_ndir
= inodes_per_group
;
288 group
= prandom_u32();
289 parent_group
= (unsigned)group
% ngroups
;
290 for (i
= 0; i
< ngroups
; i
++) {
291 group
= (parent_group
+ i
) % ngroups
;
292 desc
= ext2_get_group_desc (sb
, group
, NULL
);
293 if (!desc
|| !desc
->bg_free_inodes_count
)
295 if (le16_to_cpu(desc
->bg_used_dirs_count
) >= best_ndir
)
297 if (le16_to_cpu(desc
->bg_free_inodes_count
) < avefreei
)
299 if (le16_to_cpu(desc
->bg_free_blocks_count
) < avefreeb
)
302 best_ndir
= le16_to_cpu(desc
->bg_used_dirs_count
);
305 if (best_group
>= 0) {
314 ndirs
= 1; /* percpu_counters are approximate... */
316 blocks_per_dir
= (le32_to_cpu(es
->s_blocks_count
)-free_blocks
) / ndirs
;
318 max_dirs
= ndirs
/ ngroups
+ inodes_per_group
/ 16;
319 min_inodes
= avefreei
- inodes_per_group
/ 4;
320 min_blocks
= avefreeb
- EXT2_BLOCKS_PER_GROUP(sb
) / 4;
322 max_debt
= EXT2_BLOCKS_PER_GROUP(sb
) / max(blocks_per_dir
, BLOCK_COST
);
323 if (max_debt
* INODE_COST
> inodes_per_group
)
324 max_debt
= inodes_per_group
/ INODE_COST
;
330 for (i
= 0; i
< ngroups
; i
++) {
331 group
= (parent_group
+ i
) % ngroups
;
332 desc
= ext2_get_group_desc (sb
, group
, NULL
);
333 if (!desc
|| !desc
->bg_free_inodes_count
)
335 if (sbi
->s_debts
[group
] >= max_debt
)
337 if (le16_to_cpu(desc
->bg_used_dirs_count
) >= max_dirs
)
339 if (le16_to_cpu(desc
->bg_free_inodes_count
) < min_inodes
)
341 if (le16_to_cpu(desc
->bg_free_blocks_count
) < min_blocks
)
347 for (i
= 0; i
< ngroups
; i
++) {
348 group
= (parent_group
+ i
) % ngroups
;
349 desc
= ext2_get_group_desc (sb
, group
, NULL
);
350 if (!desc
|| !desc
->bg_free_inodes_count
)
352 if (le16_to_cpu(desc
->bg_free_inodes_count
) >= avefreei
)
358 * The free-inodes counter is approximate, and for really small
359 * filesystems the above test can fail to find any blockgroups
371 static int find_group_other(struct super_block
*sb
, struct inode
*parent
)
373 int parent_group
= EXT2_I(parent
)->i_block_group
;
374 int ngroups
= EXT2_SB(sb
)->s_groups_count
;
375 struct ext2_group_desc
*desc
;
379 * Try to place the inode in its parent directory
381 group
= parent_group
;
382 desc
= ext2_get_group_desc (sb
, group
, NULL
);
383 if (desc
&& le16_to_cpu(desc
->bg_free_inodes_count
) &&
384 le16_to_cpu(desc
->bg_free_blocks_count
))
388 * We're going to place this inode in a different blockgroup from its
389 * parent. We want to cause files in a common directory to all land in
390 * the same blockgroup. But we want files which are in a different
391 * directory which shares a blockgroup with our parent to land in a
392 * different blockgroup.
394 * So add our directory's i_ino into the starting point for the hash.
396 group
= (group
+ parent
->i_ino
) % ngroups
;
399 * Use a quadratic hash to find a group with a free inode and some
402 for (i
= 1; i
< ngroups
; i
<<= 1) {
404 if (group
>= ngroups
)
406 desc
= ext2_get_group_desc (sb
, group
, NULL
);
407 if (desc
&& le16_to_cpu(desc
->bg_free_inodes_count
) &&
408 le16_to_cpu(desc
->bg_free_blocks_count
))
413 * That failed: try linear search for a free inode, even if that group
414 * has no free blocks.
416 group
= parent_group
;
417 for (i
= 0; i
< ngroups
; i
++) {
418 if (++group
>= ngroups
)
420 desc
= ext2_get_group_desc (sb
, group
, NULL
);
421 if (desc
&& le16_to_cpu(desc
->bg_free_inodes_count
))
431 struct inode
*ext2_new_inode(struct inode
*dir
, umode_t mode
,
432 const struct qstr
*qstr
)
434 struct super_block
*sb
;
435 struct buffer_head
*bitmap_bh
= NULL
;
436 struct buffer_head
*bh2
;
439 struct inode
* inode
;
440 struct ext2_group_desc
*gdp
;
441 struct ext2_super_block
*es
;
442 struct ext2_inode_info
*ei
;
443 struct ext2_sb_info
*sbi
;
447 inode
= new_inode(sb
);
449 return ERR_PTR(-ENOMEM
);
455 if (test_opt(sb
, OLDALLOC
))
456 group
= find_group_dir(sb
, dir
);
458 group
= find_group_orlov(sb
, dir
);
460 group
= find_group_other(sb
, dir
);
467 for (i
= 0; i
< sbi
->s_groups_count
; i
++) {
468 gdp
= ext2_get_group_desc(sb
, group
, &bh2
);
470 if (++group
== sbi
->s_groups_count
)
475 bitmap_bh
= read_inode_bitmap(sb
, group
);
482 repeat_in_this_group
:
483 ino
= ext2_find_next_zero_bit((unsigned long *)bitmap_bh
->b_data
,
484 EXT2_INODES_PER_GROUP(sb
), ino
);
485 if (ino
>= EXT2_INODES_PER_GROUP(sb
)) {
487 * Rare race: find_group_xx() decided that there were
488 * free inodes in this group, but by the time we tried
489 * to allocate one, they're all gone. This can also
490 * occur because the counters which find_group_orlov()
491 * uses are approximate. So just go and search the
494 if (++group
== sbi
->s_groups_count
)
498 if (ext2_set_bit_atomic(sb_bgl_lock(sbi
, group
),
499 ino
, bitmap_bh
->b_data
)) {
500 /* we lost this inode */
501 if (++ino
>= EXT2_INODES_PER_GROUP(sb
)) {
502 /* this group is exhausted, try next group */
503 if (++group
== sbi
->s_groups_count
)
507 /* try to find free inode in the same group */
508 goto repeat_in_this_group
;
514 * Scanned all blockgroups.
519 mark_buffer_dirty(bitmap_bh
);
520 if (sb
->s_flags
& SB_SYNCHRONOUS
)
521 sync_dirty_buffer(bitmap_bh
);
524 ino
+= group
* EXT2_INODES_PER_GROUP(sb
) + 1;
525 if (ino
< EXT2_FIRST_INO(sb
) || ino
> le32_to_cpu(es
->s_inodes_count
)) {
526 ext2_error (sb
, "ext2_new_inode",
527 "reserved inode or inode > inodes count - "
528 "block_group = %d,inode=%lu", group
,
529 (unsigned long) ino
);
534 percpu_counter_add(&sbi
->s_freeinodes_counter
, -1);
536 percpu_counter_inc(&sbi
->s_dirs_counter
);
538 spin_lock(sb_bgl_lock(sbi
, group
));
539 le16_add_cpu(&gdp
->bg_free_inodes_count
, -1);
541 if (sbi
->s_debts
[group
] < 255)
542 sbi
->s_debts
[group
]++;
543 le16_add_cpu(&gdp
->bg_used_dirs_count
, 1);
545 if (sbi
->s_debts
[group
])
546 sbi
->s_debts
[group
]--;
548 spin_unlock(sb_bgl_lock(sbi
, group
));
550 mark_buffer_dirty(bh2
);
551 if (test_opt(sb
, GRPID
)) {
552 inode
->i_mode
= mode
;
553 inode
->i_uid
= current_fsuid();
554 inode
->i_gid
= dir
->i_gid
;
556 inode_init_owner(inode
, dir
, mode
);
560 inode
->i_mtime
= inode
->i_atime
= inode
->i_ctime
= current_time(inode
);
561 memset(ei
->i_data
, 0, sizeof(ei
->i_data
));
563 ext2_mask_flags(mode
, EXT2_I(dir
)->i_flags
& EXT2_FL_INHERITED
);
570 ei
->i_block_alloc_info
= NULL
;
571 ei
->i_block_group
= group
;
572 ei
->i_dir_start_lookup
= 0;
573 ei
->i_state
= EXT2_STATE_NEW
;
574 ext2_set_inode_flags(inode
);
575 spin_lock(&sbi
->s_next_gen_lock
);
576 inode
->i_generation
= sbi
->s_next_generation
++;
577 spin_unlock(&sbi
->s_next_gen_lock
);
578 if (insert_inode_locked(inode
) < 0) {
579 ext2_error(sb
, "ext2_new_inode",
580 "inode number already in use - inode=%lu",
581 (unsigned long) ino
);
586 err
= dquot_initialize(inode
);
590 err
= dquot_alloc_inode(inode
);
594 err
= ext2_init_acl(inode
, dir
);
598 err
= ext2_init_security(inode
, dir
, qstr
);
602 mark_inode_dirty(inode
);
603 ext2_debug("allocating inode %lu\n", inode
->i_ino
);
604 ext2_preread_inode(inode
);
608 dquot_free_inode(inode
);
612 inode
->i_flags
|= S_NOQUOTA
;
614 unlock_new_inode(inode
);
619 make_bad_inode(inode
);
624 unsigned long ext2_count_free_inodes (struct super_block
* sb
)
626 struct ext2_group_desc
*desc
;
627 unsigned long desc_count
= 0;
631 struct ext2_super_block
*es
;
632 unsigned long bitmap_count
= 0;
633 struct buffer_head
*bitmap_bh
= NULL
;
635 es
= EXT2_SB(sb
)->s_es
;
636 for (i
= 0; i
< EXT2_SB(sb
)->s_groups_count
; i
++) {
639 desc
= ext2_get_group_desc (sb
, i
, NULL
);
642 desc_count
+= le16_to_cpu(desc
->bg_free_inodes_count
);
644 bitmap_bh
= read_inode_bitmap(sb
, i
);
648 x
= ext2_count_free(bitmap_bh
, EXT2_INODES_PER_GROUP(sb
) / 8);
649 printk("group %d: stored = %d, counted = %u\n",
650 i
, le16_to_cpu(desc
->bg_free_inodes_count
), x
);
654 printk("ext2_count_free_inodes: stored = %lu, computed = %lu, %lu\n",
656 percpu_counter_read(&EXT2_SB(sb
)->s_freeinodes_counter
),
657 desc_count
, bitmap_count
);
660 for (i
= 0; i
< EXT2_SB(sb
)->s_groups_count
; i
++) {
661 desc
= ext2_get_group_desc (sb
, i
, NULL
);
664 desc_count
+= le16_to_cpu(desc
->bg_free_inodes_count
);
670 /* Called at mount-time, super-block is locked */
671 unsigned long ext2_count_dirs (struct super_block
* sb
)
673 unsigned long count
= 0;
676 for (i
= 0; i
< EXT2_SB(sb
)->s_groups_count
; i
++) {
677 struct ext2_group_desc
*gdp
= ext2_get_group_desc (sb
, i
, NULL
);
680 count
+= le16_to_cpu(gdp
->bg_used_dirs_count
);