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Linux/fs/ext4/ialloc.c

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  1 /*
  2  *  linux/fs/ext4/ialloc.c
  3  *
  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)
  8  *
  9  *  BSD ufs-inspired inode and directory allocation by
 10  *  Stephen Tweedie (sct@redhat.com), 1993
 11  *  Big-endian to little-endian byte-swapping/bitmaps by
 12  *        David S. Miller (davem@caip.rutgers.edu), 1995
 13  */
 14 
 15 #include <linux/time.h>
 16 #include <linux/fs.h>
 17 #include <linux/jbd2.h>
 18 #include <linux/stat.h>
 19 #include <linux/string.h>
 20 #include <linux/quotaops.h>
 21 #include <linux/buffer_head.h>
 22 #include <linux/random.h>
 23 #include <linux/bitops.h>
 24 #include <linux/blkdev.h>
 25 #include <asm/byteorder.h>
 26 
 27 #include "ext4.h"
 28 #include "ext4_jbd2.h"
 29 #include "xattr.h"
 30 #include "acl.h"
 31 
 32 #include <trace/events/ext4.h>
 33 
 34 /*
 35  * ialloc.c contains the inodes allocation and deallocation routines
 36  */
 37 
 38 /*
 39  * The free inodes are managed by bitmaps.  A file system contains several
 40  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
 41  * block for inodes, N blocks for the inode table and data blocks.
 42  *
 43  * The file system contains group descriptors which are located after the
 44  * super block.  Each descriptor contains the number of the bitmap block and
 45  * the free blocks count in the block.
 46  */
 47 
 48 /*
 49  * To avoid calling the atomic setbit hundreds or thousands of times, we only
 50  * need to use it within a single byte (to ensure we get endianness right).
 51  * We can use memset for the rest of the bitmap as there are no other users.
 52  */
 53 void ext4_mark_bitmap_end(int start_bit, int end_bit, char *bitmap)
 54 {
 55         int i;
 56 
 57         if (start_bit >= end_bit)
 58                 return;
 59 
 60         ext4_debug("mark end bits +%d through +%d used\n", start_bit, end_bit);
 61         for (i = start_bit; i < ((start_bit + 7) & ~7UL); i++)
 62                 ext4_set_bit(i, bitmap);
 63         if (i < end_bit)
 64                 memset(bitmap + (i >> 3), 0xff, (end_bit - i) >> 3);
 65 }
 66 
 67 /* Initializes an uninitialized inode bitmap */
 68 static unsigned ext4_init_inode_bitmap(struct super_block *sb,
 69                                        struct buffer_head *bh,
 70                                        ext4_group_t block_group,
 71                                        struct ext4_group_desc *gdp)
 72 {
 73         struct ext4_group_info *grp;
 74         J_ASSERT_BH(bh, buffer_locked(bh));
 75 
 76         /* If checksum is bad mark all blocks and inodes use to prevent
 77          * allocation, essentially implementing a per-group read-only flag. */
 78         if (!ext4_group_desc_csum_verify(sb, block_group, gdp)) {
 79                 ext4_error(sb, "Checksum bad for group %u", block_group);
 80                 grp = ext4_get_group_info(sb, block_group);
 81                 set_bit(EXT4_GROUP_INFO_BBITMAP_CORRUPT_BIT, &grp->bb_state);
 82                 set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);
 83                 return 0;
 84         }
 85 
 86         memset(bh->b_data, 0, (EXT4_INODES_PER_GROUP(sb) + 7) / 8);
 87         ext4_mark_bitmap_end(EXT4_INODES_PER_GROUP(sb), sb->s_blocksize * 8,
 88                         bh->b_data);
 89         ext4_inode_bitmap_csum_set(sb, block_group, gdp, bh,
 90                                    EXT4_INODES_PER_GROUP(sb) / 8);
 91         ext4_group_desc_csum_set(sb, block_group, gdp);
 92 
 93         return EXT4_INODES_PER_GROUP(sb);
 94 }
 95 
 96 void ext4_end_bitmap_read(struct buffer_head *bh, int uptodate)
 97 {
 98         if (uptodate) {
 99                 set_buffer_uptodate(bh);
100                 set_bitmap_uptodate(bh);
101         }
102         unlock_buffer(bh);
103         put_bh(bh);
104 }
105 
106 /*
107  * Read the inode allocation bitmap for a given block_group, reading
108  * into the specified slot in the superblock's bitmap cache.
109  *
110  * Return buffer_head of bitmap on success or NULL.
111  */
112 static struct buffer_head *
113 ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
114 {
115         struct ext4_group_desc *desc;
116         struct buffer_head *bh = NULL;
117         ext4_fsblk_t bitmap_blk;
118         struct ext4_group_info *grp;
119 
120         desc = ext4_get_group_desc(sb, block_group, NULL);
121         if (!desc)
122                 return NULL;
123 
124         bitmap_blk = ext4_inode_bitmap(sb, desc);
125         bh = sb_getblk(sb, bitmap_blk);
126         if (unlikely(!bh)) {
127                 ext4_error(sb, "Cannot read inode bitmap - "
128                             "block_group = %u, inode_bitmap = %llu",
129                             block_group, bitmap_blk);
130                 return NULL;
131         }
132         if (bitmap_uptodate(bh))
133                 goto verify;
134 
135         lock_buffer(bh);
136         if (bitmap_uptodate(bh)) {
137                 unlock_buffer(bh);
138                 goto verify;
139         }
140 
141         ext4_lock_group(sb, block_group);
142         if (desc->bg_flags & cpu_to_le16(EXT4_BG_INODE_UNINIT)) {
143                 ext4_init_inode_bitmap(sb, bh, block_group, desc);
144                 set_bitmap_uptodate(bh);
145                 set_buffer_uptodate(bh);
146                 set_buffer_verified(bh);
147                 ext4_unlock_group(sb, block_group);
148                 unlock_buffer(bh);
149                 return bh;
150         }
151         ext4_unlock_group(sb, block_group);
152 
153         if (buffer_uptodate(bh)) {
154                 /*
155                  * if not uninit if bh is uptodate,
156                  * bitmap is also uptodate
157                  */
158                 set_bitmap_uptodate(bh);
159                 unlock_buffer(bh);
160                 goto verify;
161         }
162         /*
163          * submit the buffer_head for reading
164          */
165         trace_ext4_load_inode_bitmap(sb, block_group);
166         bh->b_end_io = ext4_end_bitmap_read;
167         get_bh(bh);
168         submit_bh(READ | REQ_META | REQ_PRIO, bh);
169         wait_on_buffer(bh);
170         if (!buffer_uptodate(bh)) {
171                 put_bh(bh);
172                 ext4_error(sb, "Cannot read inode bitmap - "
173                            "block_group = %u, inode_bitmap = %llu",
174                            block_group, bitmap_blk);
175                 return NULL;
176         }
177 
178 verify:
179         ext4_lock_group(sb, block_group);
180         if (!buffer_verified(bh) &&
181             !ext4_inode_bitmap_csum_verify(sb, block_group, desc, bh,
182                                            EXT4_INODES_PER_GROUP(sb) / 8)) {
183                 ext4_unlock_group(sb, block_group);
184                 put_bh(bh);
185                 ext4_error(sb, "Corrupt inode bitmap - block_group = %u, "
186                            "inode_bitmap = %llu", block_group, bitmap_blk);
187                 grp = ext4_get_group_info(sb, block_group);
188                 set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);
189                 return NULL;
190         }
191         ext4_unlock_group(sb, block_group);
192         set_buffer_verified(bh);
193         return bh;
194 }
195 
196 /*
197  * NOTE! When we get the inode, we're the only people
198  * that have access to it, and as such there are no
199  * race conditions we have to worry about. The inode
200  * is not on the hash-lists, and it cannot be reached
201  * through the filesystem because the directory entry
202  * has been deleted earlier.
203  *
204  * HOWEVER: we must make sure that we get no aliases,
205  * which means that we have to call "clear_inode()"
206  * _before_ we mark the inode not in use in the inode
207  * bitmaps. Otherwise a newly created file might use
208  * the same inode number (not actually the same pointer
209  * though), and then we'd have two inodes sharing the
210  * same inode number and space on the harddisk.
211  */
212 void ext4_free_inode(handle_t *handle, struct inode *inode)
213 {
214         struct super_block *sb = inode->i_sb;
215         int is_directory;
216         unsigned long ino;
217         struct buffer_head *bitmap_bh = NULL;
218         struct buffer_head *bh2;
219         ext4_group_t block_group;
220         unsigned long bit;
221         struct ext4_group_desc *gdp;
222         struct ext4_super_block *es;
223         struct ext4_sb_info *sbi;
224         int fatal = 0, err, count, cleared;
225         struct ext4_group_info *grp;
226 
227         if (!sb) {
228                 printk(KERN_ERR "EXT4-fs: %s:%d: inode on "
229                        "nonexistent device\n", __func__, __LINE__);
230                 return;
231         }
232         if (atomic_read(&inode->i_count) > 1) {
233                 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: count=%d",
234                          __func__, __LINE__, inode->i_ino,
235                          atomic_read(&inode->i_count));
236                 return;
237         }
238         if (inode->i_nlink) {
239                 ext4_msg(sb, KERN_ERR, "%s:%d: inode #%lu: nlink=%d\n",
240                          __func__, __LINE__, inode->i_ino, inode->i_nlink);
241                 return;
242         }
243         sbi = EXT4_SB(sb);
244 
245         ino = inode->i_ino;
246         ext4_debug("freeing inode %lu\n", ino);
247         trace_ext4_free_inode(inode);
248 
249         /*
250          * Note: we must free any quota before locking the superblock,
251          * as writing the quota to disk may need the lock as well.
252          */
253         dquot_initialize(inode);
254         ext4_xattr_delete_inode(handle, inode);
255         dquot_free_inode(inode);
256         dquot_drop(inode);
257 
258         is_directory = S_ISDIR(inode->i_mode);
259 
260         /* Do this BEFORE marking the inode not in use or returning an error */
261         ext4_clear_inode(inode);
262 
263         es = EXT4_SB(sb)->s_es;
264         if (ino < EXT4_FIRST_INO(sb) || ino > le32_to_cpu(es->s_inodes_count)) {
265                 ext4_error(sb, "reserved or nonexistent inode %lu", ino);
266                 goto error_return;
267         }
268         block_group = (ino - 1) / EXT4_INODES_PER_GROUP(sb);
269         bit = (ino - 1) % EXT4_INODES_PER_GROUP(sb);
270         bitmap_bh = ext4_read_inode_bitmap(sb, block_group);
271         /* Don't bother if the inode bitmap is corrupt. */
272         grp = ext4_get_group_info(sb, block_group);
273         if (unlikely(EXT4_MB_GRP_IBITMAP_CORRUPT(grp)) || !bitmap_bh)
274                 goto error_return;
275 
276         BUFFER_TRACE(bitmap_bh, "get_write_access");
277         fatal = ext4_journal_get_write_access(handle, bitmap_bh);
278         if (fatal)
279                 goto error_return;
280 
281         fatal = -ESRCH;
282         gdp = ext4_get_group_desc(sb, block_group, &bh2);
283         if (gdp) {
284                 BUFFER_TRACE(bh2, "get_write_access");
285                 fatal = ext4_journal_get_write_access(handle, bh2);
286         }
287         ext4_lock_group(sb, block_group);
288         cleared = ext4_test_and_clear_bit(bit, bitmap_bh->b_data);
289         if (fatal || !cleared) {
290                 ext4_unlock_group(sb, block_group);
291                 goto out;
292         }
293 
294         count = ext4_free_inodes_count(sb, gdp) + 1;
295         ext4_free_inodes_set(sb, gdp, count);
296         if (is_directory) {
297                 count = ext4_used_dirs_count(sb, gdp) - 1;
298                 ext4_used_dirs_set(sb, gdp, count);
299                 percpu_counter_dec(&sbi->s_dirs_counter);
300         }
301         ext4_inode_bitmap_csum_set(sb, block_group, gdp, bitmap_bh,
302                                    EXT4_INODES_PER_GROUP(sb) / 8);
303         ext4_group_desc_csum_set(sb, block_group, gdp);
304         ext4_unlock_group(sb, block_group);
305 
306         percpu_counter_inc(&sbi->s_freeinodes_counter);
307         if (sbi->s_log_groups_per_flex) {
308                 ext4_group_t f = ext4_flex_group(sbi, block_group);
309 
310                 atomic_inc(&sbi->s_flex_groups[f].free_inodes);
311                 if (is_directory)
312                         atomic_dec(&sbi->s_flex_groups[f].used_dirs);
313         }
314         BUFFER_TRACE(bh2, "call ext4_handle_dirty_metadata");
315         fatal = ext4_handle_dirty_metadata(handle, NULL, bh2);
316 out:
317         if (cleared) {
318                 BUFFER_TRACE(bitmap_bh, "call ext4_handle_dirty_metadata");
319                 err = ext4_handle_dirty_metadata(handle, NULL, bitmap_bh);
320                 if (!fatal)
321                         fatal = err;
322         } else {
323                 ext4_error(sb, "bit already cleared for inode %lu", ino);
324                 set_bit(EXT4_GROUP_INFO_IBITMAP_CORRUPT_BIT, &grp->bb_state);
325         }
326 
327 error_return:
328         brelse(bitmap_bh);
329         ext4_std_error(sb, fatal);
330 }
331 
332 struct orlov_stats {
333         __u64 free_clusters;
334         __u32 free_inodes;
335         __u32 used_dirs;
336 };
337 
338 /*
339  * Helper function for Orlov's allocator; returns critical information
340  * for a particular block group or flex_bg.  If flex_size is 1, then g
341  * is a block group number; otherwise it is flex_bg number.
342  */
343 static void get_orlov_stats(struct super_block *sb, ext4_group_t g,
344                             int flex_size, struct orlov_stats *stats)
345 {
346         struct ext4_group_desc *desc;
347         struct flex_groups *flex_group = EXT4_SB(sb)->s_flex_groups;
348 
349         if (flex_size > 1) {
350                 stats->free_inodes = atomic_read(&flex_group[g].free_inodes);
351                 stats->free_clusters = atomic64_read(&flex_group[g].free_clusters);
352                 stats->used_dirs = atomic_read(&flex_group[g].used_dirs);
353                 return;
354         }
355 
356         desc = ext4_get_group_desc(sb, g, NULL);
357         if (desc) {
358                 stats->free_inodes = ext4_free_inodes_count(sb, desc);
359                 stats->free_clusters = ext4_free_group_clusters(sb, desc);
360                 stats->used_dirs = ext4_used_dirs_count(sb, desc);
361         } else {
362                 stats->free_inodes = 0;
363                 stats->free_clusters = 0;
364                 stats->used_dirs = 0;
365         }
366 }
367 
368 /*
369  * Orlov's allocator for directories.
370  *
371  * We always try to spread first-level directories.
372  *
373  * If there are blockgroups with both free inodes and free blocks counts
374  * not worse than average we return one with smallest directory count.
375  * Otherwise we simply return a random group.
376  *
377  * For the rest rules look so:
378  *
379  * It's OK to put directory into a group unless
380  * it has too many directories already (max_dirs) or
381  * it has too few free inodes left (min_inodes) or
382  * it has too few free blocks left (min_blocks) or
383  * Parent's group is preferred, if it doesn't satisfy these
384  * conditions we search cyclically through the rest. If none
385  * of the groups look good we just look for a group with more
386  * free inodes than average (starting at parent's group).
387  */
388 
389 static int find_group_orlov(struct super_block *sb, struct inode *parent,
390                             ext4_group_t *group, umode_t mode,
391                             const struct qstr *qstr)
392 {
393         ext4_group_t parent_group = EXT4_I(parent)->i_block_group;
394         struct ext4_sb_info *sbi = EXT4_SB(sb);
395         ext4_group_t real_ngroups = ext4_get_groups_count(sb);
396         int inodes_per_group = EXT4_INODES_PER_GROUP(sb);
397         unsigned int freei, avefreei, grp_free;
398         ext4_fsblk_t freeb, avefreec;
399         unsigned int ndirs;
400         int max_dirs, min_inodes;
401         ext4_grpblk_t min_clusters;
402         ext4_group_t i, grp, g, ngroups;
403         struct ext4_group_desc *desc;
404         struct orlov_stats stats;
405         int flex_size = ext4_flex_bg_size(sbi);
406         struct dx_hash_info hinfo;
407 
408         ngroups = real_ngroups;
409         if (flex_size > 1) {
410                 ngroups = (real_ngroups + flex_size - 1) >>
411                         sbi->s_log_groups_per_flex;
412                 parent_group >>= sbi->s_log_groups_per_flex;
413         }
414 
415         freei = percpu_counter_read_positive(&sbi->s_freeinodes_counter);
416         avefreei = freei / ngroups;
417         freeb = EXT4_C2B(sbi,
418                 percpu_counter_read_positive(&sbi->s_freeclusters_counter));
419         avefreec = freeb;
420         do_div(avefreec, ngroups);
421         ndirs = percpu_counter_read_positive(&sbi->s_dirs_counter);
422 
423         if (S_ISDIR(mode) &&
424             ((parent == sb->s_root->d_inode) ||
425              (ext4_test_inode_flag(parent, EXT4_INODE_TOPDIR)))) {
426                 int best_ndir = inodes_per_group;
427                 int ret = -1;
428 
429                 if (qstr) {
430                         hinfo.hash_version = DX_HASH_HALF_MD4;
431                         hinfo.seed = sbi->s_hash_seed;
432                         ext4fs_dirhash(qstr->name, qstr->len, &hinfo);
433                         grp = hinfo.hash;
434                 } else
435                         grp = prandom_u32();
436                 parent_group = (unsigned)grp % ngroups;
437                 for (i = 0; i < ngroups; i++) {
438                         g = (parent_group + i) % ngroups;
439                         get_orlov_stats(sb, g, flex_size, &stats);
440                         if (!stats.free_inodes)
441                                 continue;
442                         if (stats.used_dirs >= best_ndir)
443                                 continue;
444                         if (stats.free_inodes < avefreei)
445                                 continue;
446                         if (stats.free_clusters < avefreec)
447                                 continue;
448                         grp = g;
449                         ret = 0;
450                         best_ndir = stats.used_dirs;
451                 }
452                 if (ret)
453                         goto fallback;
454         found_flex_bg:
455                 if (flex_size == 1) {
456                         *group = grp;
457                         return 0;
458                 }
459 
460                 /*
461                  * We pack inodes at the beginning of the flexgroup's
462                  * inode tables.  Block allocation decisions will do
463                  * something similar, although regular files will
464                  * start at 2nd block group of the flexgroup.  See
465                  * ext4_ext_find_goal() and ext4_find_near().
466                  */
467                 grp *= flex_size;
468                 for (i = 0; i < flex_size; i++) {
469                         if (grp+i >= real_ngroups)
470                                 break;
471                         desc = ext4_get_group_desc(sb, grp+i, NULL);
472                         if (desc && ext4_free_inodes_count(sb, desc)) {
473                                 *group = grp+i;
474                                 return 0;
475                         }
476                 }
477                 goto fallback;
478         }
479 
480         max_dirs = ndirs / ngroups + inodes_per_group / 16;
481         min_inodes = avefreei - inodes_per_group*flex_size / 4;
482         if (min_inodes < 1)
483                 min_inodes = 1;
484         min_clusters = avefreec - EXT4_CLUSTERS_PER_GROUP(sb)*flex_size / 4;
485 
486         /*
487          * Start looking in the flex group where we last allocated an
488          * inode for this parent directory
489          */
490         if (EXT4_I(parent)->i_last_alloc_group != ~0) {
491                 parent_group = EXT4_I(parent)->i_last_alloc_group;
492                 if (flex_size > 1)
493                         parent_group >>= sbi->s_log_groups_per_flex;
494         }
495 
496         for (i = 0; i < ngroups; i++) {
497                 grp = (parent_group + i) % ngroups;
498                 get_orlov_stats(sb, grp, flex_size, &stats);
499                 if (stats.used_dirs >= max_dirs)
500                         continue;
501                 if (stats.free_inodes < min_inodes)
502                         continue;
503                 if (stats.free_clusters < min_clusters)
504                         continue;
505                 goto found_flex_bg;
506         }
507 
508 fallback:
509         ngroups = real_ngroups;
510         avefreei = freei / ngroups;
511 fallback_retry:
512         parent_group = EXT4_I(parent)->i_block_group;
513         for (i = 0; i < ngroups; i++) {
514                 grp = (parent_group + i) % ngroups;
515                 desc = ext4_get_group_desc(sb, grp, NULL);
516                 if (desc) {
517                         grp_free = ext4_free_inodes_count(sb, desc);
518                         if (grp_free && grp_free >= avefreei) {
519                                 *group = grp;
520                                 return 0;
521                         }
522                 }
523         }
524 
525         if (avefreei) {
526                 /*
527                  * The free-inodes counter is approximate, and for really small
528                  * filesystems the above test can fail to find any blockgroups
529                  */
530                 avefreei = 0;
531                 goto fallback_retry;
532         }
533 
534         return -1;
535 }
536 
537 static int find_group_other(struct super_block *sb, struct inode *parent,
538                             ext4_group_t *group, umode_t mode)
539 {
540         ext4_group_t parent_group = EXT4_I(parent)->i_block_group;
541         ext4_group_t i, last, ngroups = ext4_get_groups_count(sb);
542         struct ext4_group_desc *desc;
543         int flex_size = ext4_flex_bg_size(EXT4_SB(sb));
544 
545         /*
546          * Try to place the inode is the same flex group as its
547          * parent.  If we can't find space, use the Orlov algorithm to
548          * find another flex group, and store that information in the
549          * parent directory's inode information so that use that flex
550          * group for future allocations.
551          */
552         if (flex_size > 1) {
553                 int retry = 0;
554 
555         try_again:
556                 parent_group &= ~(flex_size-1);
557                 last = parent_group + flex_size;
558                 if (last > ngroups)
559                         last = ngroups;
560                 for  (i = parent_group; i < last; i++) {
561                         desc = ext4_get_group_desc(sb, i, NULL);
562                         if (desc && ext4_free_inodes_count(sb, desc)) {
563                                 *group = i;
564                                 return 0;
565                         }
566                 }
567                 if (!retry && EXT4_I(parent)->i_last_alloc_group != ~0) {
568                         retry = 1;
569                         parent_group = EXT4_I(parent)->i_last_alloc_group;
570                         goto try_again;
571                 }
572                 /*
573                  * If this didn't work, use the Orlov search algorithm
574                  * to find a new flex group; we pass in the mode to
575                  * avoid the topdir algorithms.
576                  */
577                 *group = parent_group + flex_size;
578                 if (*group > ngroups)
579                         *group = 0;
580                 return find_group_orlov(sb, parent, group, mode, NULL);
581         }
582 
583         /*
584          * Try to place the inode in its parent directory
585          */
586         *group = parent_group;
587         desc = ext4_get_group_desc(sb, *group, NULL);
588         if (desc && ext4_free_inodes_count(sb, desc) &&
589             ext4_free_group_clusters(sb, desc))
590                 return 0;
591 
592         /*
593          * We're going to place this inode in a different blockgroup from its
594          * parent.  We want to cause files in a common directory to all land in
595          * the same blockgroup.  But we want files which are in a different
596          * directory which shares a blockgroup with our parent to land in a
597          * different blockgroup.
598          *
599          * So add our directory's i_ino into the starting point for the hash.
600          */
601         *group = (*group + parent->i_ino) % ngroups;
602 
603         /*
604          * Use a quadratic hash to find a group with a free inode and some free
605          * blocks.
606          */
607         for (i = 1; i < ngroups; i <<= 1) {
608                 *group += i;
609                 if (*group >= ngroups)
610                         *group -= ngroups;
611                 desc = ext4_get_group_desc(sb, *group, NULL);
612                 if (desc && ext4_free_inodes_count(sb, desc) &&
613                     ext4_free_group_clusters(sb, desc))
614                         return 0;
615         }
616 
617         /*
618          * That failed: try linear search for a free inode, even if that group
619          * has no free blocks.
620          */
621         *group = parent_group;
622         for (i = 0; i < ngroups; i++) {
623                 if (++*group >= ngroups)
624                         *group = 0;
625                 desc = ext4_get_group_desc(sb, *group, NULL);
626                 if (desc && ext4_free_inodes_count(sb, desc))
627                         return 0;
628         }
629 
630         return -1;
631 }
632 
633 /*
634  * In no journal mode, if an inode has recently been deleted, we want
635  * to avoid reusing it until we're reasonably sure the inode table
636  * block has been written back to disk.  (Yes, these values are
637  * somewhat arbitrary...)
638  */
639 #define RECENTCY_MIN    5
640 #define RECENTCY_DIRTY  30
641 
642 static int recently_deleted(struct super_block *sb, ext4_group_t group, int ino)
643 {
644         struct ext4_group_desc  *gdp;
645         struct ext4_inode       *raw_inode;
646         struct buffer_head      *bh;
647         unsigned long           dtime, now;
648         int     inodes_per_block = EXT4_SB(sb)->s_inodes_per_block;
649         int     offset, ret = 0, recentcy = RECENTCY_MIN;
650 
651         gdp = ext4_get_group_desc(sb, group, NULL);
652         if (unlikely(!gdp))
653                 return 0;
654 
655         bh = sb_getblk(sb, ext4_inode_table(sb, gdp) +
656                        (ino / inodes_per_block));
657         if (unlikely(!bh) || !buffer_uptodate(bh))
658                 /*
659                  * If the block is not in the buffer cache, then it
660                  * must have been written out.
661                  */
662                 goto out;
663 
664         offset = (ino % inodes_per_block) * EXT4_INODE_SIZE(sb);
665         raw_inode = (struct ext4_inode *) (bh->b_data + offset);
666         dtime = le32_to_cpu(raw_inode->i_dtime);
667         now = get_seconds();
668         if (buffer_dirty(bh))
669                 recentcy += RECENTCY_DIRTY;
670 
671         if (dtime && (dtime < now) && (now < dtime + recentcy))
672                 ret = 1;
673 out:
674         brelse(bh);
675         return ret;
676 }
677 
678 /*
679  * There are two policies for allocating an inode.  If the new inode is
680  * a directory, then a forward search is made for a block group with both
681  * free space and a low directory-to-inode ratio; if that fails, then of
682  * the groups with above-average free space, that group with the fewest
683  * directories already is chosen.
684  *
685  * For other inodes, search forward from the parent directory's block
686  * group to find a free inode.
687  */
688 struct inode *__ext4_new_inode(handle_t *handle, struct inode *dir,
689                                umode_t mode, const struct qstr *qstr,
690                                __u32 goal, uid_t *owner, int handle_type,
691                                unsigned int line_no, int nblocks)
692 {
693         struct super_block *sb;
694         struct buffer_head *inode_bitmap_bh = NULL;
695         struct buffer_head *group_desc_bh;
696         ext4_group_t ngroups, group = 0;
697         unsigned long ino = 0;
698         struct inode *inode;
699         struct ext4_group_desc *gdp = NULL;
700         struct ext4_inode_info *ei;
701         struct ext4_sb_info *sbi;
702         int ret2, err = 0;
703         struct inode *ret;
704         ext4_group_t i;
705         ext4_group_t flex_group;
706         struct ext4_group_info *grp;
707 
708         /* Cannot create files in a deleted directory */
709         if (!dir || !dir->i_nlink)
710                 return ERR_PTR(-EPERM);
711 
712         sb = dir->i_sb;
713         ngroups = ext4_get_groups_count(sb);
714         trace_ext4_request_inode(dir, mode);
715         inode = new_inode(sb);
716         if (!inode)
717                 return ERR_PTR(-ENOMEM);
718         ei = EXT4_I(inode);
719         sbi = EXT4_SB(sb);
720 
721         /*
722          * Initalize owners and quota early so that we don't have to account
723          * for quota initialization worst case in standard inode creating
724          * transaction
725          */
726         if (owner) {
727                 inode->i_mode = mode;
728                 i_uid_write(inode, owner[0]);
729                 i_gid_write(inode, owner[1]);
730         } else if (test_opt(sb, GRPID)) {
731                 inode->i_mode = mode;
732                 inode->i_uid = current_fsuid();
733                 inode->i_gid = dir->i_gid;
734         } else
735                 inode_init_owner(inode, dir, mode);
736         dquot_initialize(inode);
737 
738         if (!goal)
739                 goal = sbi->s_inode_goal;
740 
741         if (goal && goal <= le32_to_cpu(sbi->s_es->s_inodes_count)) {
742                 group = (goal - 1) / EXT4_INODES_PER_GROUP(sb);
743                 ino = (goal - 1) % EXT4_INODES_PER_GROUP(sb);
744                 ret2 = 0;
745                 goto got_group;
746         }
747 
748         if (S_ISDIR(mode))
749                 ret2 = find_group_orlov(sb, dir, &group, mode, qstr);
750         else
751                 ret2 = find_group_other(sb, dir, &group, mode);
752 
753 got_group:
754         EXT4_I(dir)->i_last_alloc_group = group;
755         err = -ENOSPC;
756         if (ret2 == -1)
757                 goto out;
758 
759         /*
760          * Normally we will only go through one pass of this loop,
761          * unless we get unlucky and it turns out the group we selected
762          * had its last inode grabbed by someone else.
763          */
764         for (i = 0; i < ngroups; i++, ino = 0) {
765                 err = -EIO;
766 
767                 gdp = ext4_get_group_desc(sb, group, &group_desc_bh);
768                 if (!gdp)
769                         goto out;
770 
771                 /*
772                  * Check free inodes count before loading bitmap.
773                  */
774                 if (ext4_free_inodes_count(sb, gdp) == 0) {
775                         if (++group == ngroups)
776                                 group = 0;
777                         continue;
778                 }
779 
780                 grp = ext4_get_group_info(sb, group);
781                 /* Skip groups with already-known suspicious inode tables */
782                 if (EXT4_MB_GRP_IBITMAP_CORRUPT(grp)) {
783                         if (++group == ngroups)
784                                 group = 0;
785                         continue;
786                 }
787 
788                 brelse(inode_bitmap_bh);
789                 inode_bitmap_bh = ext4_read_inode_bitmap(sb, group);
790                 /* Skip groups with suspicious inode tables */
791                 if (EXT4_MB_GRP_IBITMAP_CORRUPT(grp) || !inode_bitmap_bh) {
792                         if (++group == ngroups)
793                                 group = 0;
794                         continue;
795                 }
796 
797 repeat_in_this_group:
798                 ino = ext4_find_next_zero_bit((unsigned long *)
799                                               inode_bitmap_bh->b_data,
800                                               EXT4_INODES_PER_GROUP(sb), ino);
801                 if (ino >= EXT4_INODES_PER_GROUP(sb))
802                         goto next_group;
803                 if (group == 0 && (ino+1) < EXT4_FIRST_INO(sb)) {
804                         ext4_error(sb, "reserved inode found cleared - "
805                                    "inode=%lu", ino + 1);
806                         continue;
807                 }
808                 if ((EXT4_SB(sb)->s_journal == NULL) &&
809                     recently_deleted(sb, group, ino)) {
810                         ino++;
811                         goto next_inode;
812                 }
813                 if (!handle) {
814                         BUG_ON(nblocks <= 0);
815                         handle = __ext4_journal_start_sb(dir->i_sb, line_no,
816                                                          handle_type, nblocks,
817                                                          0);
818                         if (IS_ERR(handle)) {
819                                 err = PTR_ERR(handle);
820                                 ext4_std_error(sb, err);
821                                 goto out;
822                         }
823                 }
824                 BUFFER_TRACE(inode_bitmap_bh, "get_write_access");
825                 err = ext4_journal_get_write_access(handle, inode_bitmap_bh);
826                 if (err) {
827                         ext4_std_error(sb, err);
828                         goto out;
829                 }
830                 ext4_lock_group(sb, group);
831                 ret2 = ext4_test_and_set_bit(ino, inode_bitmap_bh->b_data);
832                 ext4_unlock_group(sb, group);
833                 ino++;          /* the inode bitmap is zero-based */
834                 if (!ret2)
835                         goto got; /* we grabbed the inode! */
836 next_inode:
837                 if (ino < EXT4_INODES_PER_GROUP(sb))
838                         goto repeat_in_this_group;
839 next_group:
840                 if (++group == ngroups)
841                         group = 0;
842         }
843         err = -ENOSPC;
844         goto out;
845 
846 got:
847         BUFFER_TRACE(inode_bitmap_bh, "call ext4_handle_dirty_metadata");
848         err = ext4_handle_dirty_metadata(handle, NULL, inode_bitmap_bh);
849         if (err) {
850                 ext4_std_error(sb, err);
851                 goto out;
852         }
853 
854         BUFFER_TRACE(group_desc_bh, "get_write_access");
855         err = ext4_journal_get_write_access(handle, group_desc_bh);
856         if (err) {
857                 ext4_std_error(sb, err);
858                 goto out;
859         }
860 
861         /* We may have to initialize the block bitmap if it isn't already */
862         if (ext4_has_group_desc_csum(sb) &&
863             gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
864                 struct buffer_head *block_bitmap_bh;
865 
866                 block_bitmap_bh = ext4_read_block_bitmap(sb, group);
867                 if (!block_bitmap_bh) {
868                         err = -EIO;
869                         goto out;
870                 }
871                 BUFFER_TRACE(block_bitmap_bh, "get block bitmap access");
872                 err = ext4_journal_get_write_access(handle, block_bitmap_bh);
873                 if (err) {
874                         brelse(block_bitmap_bh);
875                         ext4_std_error(sb, err);
876                         goto out;
877                 }
878 
879                 BUFFER_TRACE(block_bitmap_bh, "dirty block bitmap");
880                 err = ext4_handle_dirty_metadata(handle, NULL, block_bitmap_bh);
881 
882                 /* recheck and clear flag under lock if we still need to */
883                 ext4_lock_group(sb, group);
884                 if (gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
885                         gdp->bg_flags &= cpu_to_le16(~EXT4_BG_BLOCK_UNINIT);
886                         ext4_free_group_clusters_set(sb, gdp,
887                                 ext4_free_clusters_after_init(sb, group, gdp));
888                         ext4_block_bitmap_csum_set(sb, group, gdp,
889                                                    block_bitmap_bh);
890                         ext4_group_desc_csum_set(sb, group, gdp);
891                 }
892                 ext4_unlock_group(sb, group);
893                 brelse(block_bitmap_bh);
894 
895                 if (err) {
896                         ext4_std_error(sb, err);
897                         goto out;
898                 }
899         }
900 
901         /* Update the relevant bg descriptor fields */
902         if (ext4_has_group_desc_csum(sb)) {
903                 int free;
904                 struct ext4_group_info *grp = ext4_get_group_info(sb, group);
905 
906                 down_read(&grp->alloc_sem); /* protect vs itable lazyinit */
907                 ext4_lock_group(sb, group); /* while we modify the bg desc */
908                 free = EXT4_INODES_PER_GROUP(sb) -
909                         ext4_itable_unused_count(sb, gdp);
910                 if (gdp->bg_flags & cpu_to_le16(EXT4_BG_INODE_UNINIT)) {
911                         gdp->bg_flags &= cpu_to_le16(~EXT4_BG_INODE_UNINIT);
912                         free = 0;
913                 }
914                 /*
915                  * Check the relative inode number against the last used
916                  * relative inode number in this group. if it is greater
917                  * we need to update the bg_itable_unused count
918                  */
919                 if (ino > free)
920                         ext4_itable_unused_set(sb, gdp,
921                                         (EXT4_INODES_PER_GROUP(sb) - ino));
922                 up_read(&grp->alloc_sem);
923         } else {
924                 ext4_lock_group(sb, group);
925         }
926 
927         ext4_free_inodes_set(sb, gdp, ext4_free_inodes_count(sb, gdp) - 1);
928         if (S_ISDIR(mode)) {
929                 ext4_used_dirs_set(sb, gdp, ext4_used_dirs_count(sb, gdp) + 1);
930                 if (sbi->s_log_groups_per_flex) {
931                         ext4_group_t f = ext4_flex_group(sbi, group);
932 
933                         atomic_inc(&sbi->s_flex_groups[f].used_dirs);
934                 }
935         }
936         if (ext4_has_group_desc_csum(sb)) {
937                 ext4_inode_bitmap_csum_set(sb, group, gdp, inode_bitmap_bh,
938                                            EXT4_INODES_PER_GROUP(sb) / 8);
939                 ext4_group_desc_csum_set(sb, group, gdp);
940         }
941         ext4_unlock_group(sb, group);
942 
943         BUFFER_TRACE(group_desc_bh, "call ext4_handle_dirty_metadata");
944         err = ext4_handle_dirty_metadata(handle, NULL, group_desc_bh);
945         if (err) {
946                 ext4_std_error(sb, err);
947                 goto out;
948         }
949 
950         percpu_counter_dec(&sbi->s_freeinodes_counter);
951         if (S_ISDIR(mode))
952                 percpu_counter_inc(&sbi->s_dirs_counter);
953 
954         if (sbi->s_log_groups_per_flex) {
955                 flex_group = ext4_flex_group(sbi, group);
956                 atomic_dec(&sbi->s_flex_groups[flex_group].free_inodes);
957         }
958 
959         inode->i_ino = ino + group * EXT4_INODES_PER_GROUP(sb);
960         /* This is the optimal IO size (for stat), not the fs block size */
961         inode->i_blocks = 0;
962         inode->i_mtime = inode->i_atime = inode->i_ctime = ei->i_crtime =
963                                                        ext4_current_time(inode);
964 
965         memset(ei->i_data, 0, sizeof(ei->i_data));
966         ei->i_dir_start_lookup = 0;
967         ei->i_disksize = 0;
968 
969         /* Don't inherit extent flag from directory, amongst others. */
970         ei->i_flags =
971                 ext4_mask_flags(mode, EXT4_I(dir)->i_flags & EXT4_FL_INHERITED);
972         ei->i_file_acl = 0;
973         ei->i_dtime = 0;
974         ei->i_block_group = group;
975         ei->i_last_alloc_group = ~0;
976 
977         ext4_set_inode_flags(inode);
978         if (IS_DIRSYNC(inode))
979                 ext4_handle_sync(handle);
980         if (insert_inode_locked(inode) < 0) {
981                 /*
982                  * Likely a bitmap corruption causing inode to be allocated
983                  * twice.
984                  */
985                 err = -EIO;
986                 ext4_error(sb, "failed to insert inode %lu: doubly allocated?",
987                            inode->i_ino);
988                 goto out;
989         }
990         spin_lock(&sbi->s_next_gen_lock);
991         inode->i_generation = sbi->s_next_generation++;
992         spin_unlock(&sbi->s_next_gen_lock);
993 
994         /* Precompute checksum seed for inode metadata */
995         if (ext4_has_metadata_csum(sb)) {
996                 __u32 csum;
997                 __le32 inum = cpu_to_le32(inode->i_ino);
998                 __le32 gen = cpu_to_le32(inode->i_generation);
999                 csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&inum,
1000                                    sizeof(inum));
1001                 ei->i_csum_seed = ext4_chksum(sbi, csum, (__u8 *)&gen,
1002                                               sizeof(gen));
1003         }
1004 
1005         ext4_clear_state_flags(ei); /* Only relevant on 32-bit archs */
1006         ext4_set_inode_state(inode, EXT4_STATE_NEW);
1007 
1008         ei->i_extra_isize = EXT4_SB(sb)->s_want_extra_isize;
1009 
1010         ei->i_inline_off = 0;
1011         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_INLINE_DATA))
1012                 ext4_set_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA);
1013 
1014         ret = inode;
1015         err = dquot_alloc_inode(inode);
1016         if (err)
1017                 goto fail_drop;
1018 
1019         err = ext4_init_acl(handle, inode, dir);
1020         if (err)
1021                 goto fail_free_drop;
1022 
1023         err = ext4_init_security(handle, inode, dir, qstr);
1024         if (err)
1025                 goto fail_free_drop;
1026 
1027         if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS)) {
1028                 /* set extent flag only for directory, file and normal symlink*/
1029                 if (S_ISDIR(mode) || S_ISREG(mode) || S_ISLNK(mode)) {
1030                         ext4_set_inode_flag(inode, EXT4_INODE_EXTENTS);
1031                         ext4_ext_tree_init(handle, inode);
1032                 }
1033         }
1034 
1035         if (ext4_handle_valid(handle)) {
1036                 ei->i_sync_tid = handle->h_transaction->t_tid;
1037                 ei->i_datasync_tid = handle->h_transaction->t_tid;
1038         }
1039 
1040         err = ext4_mark_inode_dirty(handle, inode);
1041         if (err) {
1042                 ext4_std_error(sb, err);
1043                 goto fail_free_drop;
1044         }
1045 
1046         ext4_debug("allocating inode %lu\n", inode->i_ino);
1047         trace_ext4_allocate_inode(inode, dir, mode);
1048         brelse(inode_bitmap_bh);
1049         return ret;
1050 
1051 fail_free_drop:
1052         dquot_free_inode(inode);
1053 fail_drop:
1054         clear_nlink(inode);
1055         unlock_new_inode(inode);
1056 out:
1057         dquot_drop(inode);
1058         inode->i_flags |= S_NOQUOTA;
1059         iput(inode);
1060         brelse(inode_bitmap_bh);
1061         return ERR_PTR(err);
1062 }
1063 
1064 /* Verify that we are loading a valid orphan from disk */
1065 struct inode *ext4_orphan_get(struct super_block *sb, unsigned long ino)
1066 {
1067         unsigned long max_ino = le32_to_cpu(EXT4_SB(sb)->s_es->s_inodes_count);
1068         ext4_group_t block_group;
1069         int bit;
1070         struct buffer_head *bitmap_bh;
1071         struct inode *inode = NULL;
1072         long err = -EIO;
1073 
1074         /* Error cases - e2fsck has already cleaned up for us */
1075         if (ino > max_ino) {
1076                 ext4_warning(sb, "bad orphan ino %lu!  e2fsck was run?", ino);
1077                 goto error;
1078         }
1079 
1080         block_group = (ino - 1) / EXT4_INODES_PER_GROUP(sb);
1081         bit = (ino - 1) % EXT4_INODES_PER_GROUP(sb);
1082         bitmap_bh = ext4_read_inode_bitmap(sb, block_group);
1083         if (!bitmap_bh) {
1084                 ext4_warning(sb, "inode bitmap error for orphan %lu", ino);
1085                 goto error;
1086         }
1087 
1088         /* Having the inode bit set should be a 100% indicator that this
1089          * is a valid orphan (no e2fsck run on fs).  Orphans also include
1090          * inodes that were being truncated, so we can't check i_nlink==0.
1091          */
1092         if (!ext4_test_bit(bit, bitmap_bh->b_data))
1093                 goto bad_orphan;
1094 
1095         inode = ext4_iget(sb, ino);
1096         if (IS_ERR(inode))
1097                 goto iget_failed;
1098 
1099         /*
1100          * If the orphans has i_nlinks > 0 then it should be able to
1101          * be truncated, otherwise it won't be removed from the orphan
1102          * list during processing and an infinite loop will result.
1103          * Similarly, it must not be a bad inode.
1104          */
1105         if ((inode->i_nlink && !ext4_can_truncate(inode)) ||
1106             is_bad_inode(inode))
1107                 goto bad_orphan;
1108 
1109         if (NEXT_ORPHAN(inode) > max_ino)
1110                 goto bad_orphan;
1111         brelse(bitmap_bh);
1112         return inode;
1113 
1114 iget_failed:
1115         err = PTR_ERR(inode);
1116         inode = NULL;
1117 bad_orphan:
1118         ext4_warning(sb, "bad orphan inode %lu!  e2fsck was run?", ino);
1119         printk(KERN_WARNING "ext4_test_bit(bit=%d, block=%llu) = %d\n",
1120                bit, (unsigned long long)bitmap_bh->b_blocknr,
1121                ext4_test_bit(bit, bitmap_bh->b_data));
1122         printk(KERN_WARNING "inode=%p\n", inode);
1123         if (inode) {
1124                 printk(KERN_WARNING "is_bad_inode(inode)=%d\n",
1125                        is_bad_inode(inode));
1126                 printk(KERN_WARNING "NEXT_ORPHAN(inode)=%u\n",
1127                        NEXT_ORPHAN(inode));
1128                 printk(KERN_WARNING "max_ino=%lu\n", max_ino);
1129                 printk(KERN_WARNING "i_nlink=%u\n", inode->i_nlink);
1130                 /* Avoid freeing blocks if we got a bad deleted inode */
1131                 if (inode->i_nlink == 0)
1132                         inode->i_blocks = 0;
1133                 iput(inode);
1134         }
1135         brelse(bitmap_bh);
1136 error:
1137         return ERR_PTR(err);
1138 }
1139 
1140 unsigned long ext4_count_free_inodes(struct super_block *sb)
1141 {
1142         unsigned long desc_count;
1143         struct ext4_group_desc *gdp;
1144         ext4_group_t i, ngroups = ext4_get_groups_count(sb);
1145 #ifdef EXT4FS_DEBUG
1146         struct ext4_super_block *es;
1147         unsigned long bitmap_count, x;
1148         struct buffer_head *bitmap_bh = NULL;
1149 
1150         es = EXT4_SB(sb)->s_es;
1151         desc_count = 0;
1152         bitmap_count = 0;
1153         gdp = NULL;
1154         for (i = 0; i < ngroups; i++) {
1155                 gdp = ext4_get_group_desc(sb, i, NULL);
1156                 if (!gdp)
1157                         continue;
1158                 desc_count += ext4_free_inodes_count(sb, gdp);
1159                 brelse(bitmap_bh);
1160                 bitmap_bh = ext4_read_inode_bitmap(sb, i);
1161                 if (!bitmap_bh)
1162                         continue;
1163 
1164                 x = ext4_count_free(bitmap_bh->b_data,
1165                                     EXT4_INODES_PER_GROUP(sb) / 8);
1166                 printk(KERN_DEBUG "group %lu: stored = %d, counted = %lu\n",
1167                         (unsigned long) i, ext4_free_inodes_count(sb, gdp), x);
1168                 bitmap_count += x;
1169         }
1170         brelse(bitmap_bh);
1171         printk(KERN_DEBUG "ext4_count_free_inodes: "
1172                "stored = %u, computed = %lu, %lu\n",
1173                le32_to_cpu(es->s_free_inodes_count), desc_count, bitmap_count);
1174         return desc_count;
1175 #else
1176         desc_count = 0;
1177         for (i = 0; i < ngroups; i++) {
1178                 gdp = ext4_get_group_desc(sb, i, NULL);
1179                 if (!gdp)
1180                         continue;
1181                 desc_count += ext4_free_inodes_count(sb, gdp);
1182                 cond_resched();
1183         }
1184         return desc_count;
1185 #endif
1186 }
1187 
1188 /* Called at mount-time, super-block is locked */
1189 unsigned long ext4_count_dirs(struct super_block * sb)
1190 {
1191         unsigned long count = 0;
1192         ext4_group_t i, ngroups = ext4_get_groups_count(sb);
1193 
1194         for (i = 0; i < ngroups; i++) {
1195                 struct ext4_group_desc *gdp = ext4_get_group_desc(sb, i, NULL);
1196                 if (!gdp)
1197                         continue;
1198                 count += ext4_used_dirs_count(sb, gdp);
1199         }
1200         return count;
1201 }
1202 
1203 /*
1204  * Zeroes not yet zeroed inode table - just write zeroes through the whole
1205  * inode table. Must be called without any spinlock held. The only place
1206  * where it is called from on active part of filesystem is ext4lazyinit
1207  * thread, so we do not need any special locks, however we have to prevent
1208  * inode allocation from the current group, so we take alloc_sem lock, to
1209  * block ext4_new_inode() until we are finished.
1210  */
1211 int ext4_init_inode_table(struct super_block *sb, ext4_group_t group,
1212                                  int barrier)
1213 {
1214         struct ext4_group_info *grp = ext4_get_group_info(sb, group);
1215         struct ext4_sb_info *sbi = EXT4_SB(sb);
1216         struct ext4_group_desc *gdp = NULL;
1217         struct buffer_head *group_desc_bh;
1218         handle_t *handle;
1219         ext4_fsblk_t blk;
1220         int num, ret = 0, used_blks = 0;
1221 
1222         /* This should not happen, but just to be sure check this */
1223         if (sb->s_flags & MS_RDONLY) {
1224                 ret = 1;
1225                 goto out;
1226         }
1227 
1228         gdp = ext4_get_group_desc(sb, group, &group_desc_bh);
1229         if (!gdp)
1230                 goto out;
1231 
1232         /*
1233          * We do not need to lock this, because we are the only one
1234          * handling this flag.
1235          */
1236         if (gdp->bg_flags & cpu_to_le16(EXT4_BG_INODE_ZEROED))
1237                 goto out;
1238 
1239         handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
1240         if (IS_ERR(handle)) {
1241                 ret = PTR_ERR(handle);
1242                 goto out;
1243         }
1244 
1245         down_write(&grp->alloc_sem);
1246         /*
1247          * If inode bitmap was already initialized there may be some
1248          * used inodes so we need to skip blocks with used inodes in
1249          * inode table.
1250          */
1251         if (!(gdp->bg_flags & cpu_to_le16(EXT4_BG_INODE_UNINIT)))
1252                 used_blks = DIV_ROUND_UP((EXT4_INODES_PER_GROUP(sb) -
1253                             ext4_itable_unused_count(sb, gdp)),
1254                             sbi->s_inodes_per_block);
1255 
1256         if ((used_blks < 0) || (used_blks > sbi->s_itb_per_group)) {
1257                 ext4_error(sb, "Something is wrong with group %u: "
1258                            "used itable blocks: %d; "
1259                            "itable unused count: %u",
1260                            group, used_blks,
1261                            ext4_itable_unused_count(sb, gdp));
1262                 ret = 1;
1263                 goto err_out;
1264         }
1265 
1266         blk = ext4_inode_table(sb, gdp) + used_blks;
1267         num = sbi->s_itb_per_group - used_blks;
1268 
1269         BUFFER_TRACE(group_desc_bh, "get_write_access");
1270         ret = ext4_journal_get_write_access(handle,
1271                                             group_desc_bh);
1272         if (ret)
1273                 goto err_out;
1274 
1275         /*
1276          * Skip zeroout if the inode table is full. But we set the ZEROED
1277          * flag anyway, because obviously, when it is full it does not need
1278          * further zeroing.
1279          */
1280         if (unlikely(num == 0))
1281                 goto skip_zeroout;
1282 
1283         ext4_debug("going to zero out inode table in group %d\n",
1284                    group);
1285         ret = sb_issue_zeroout(sb, blk, num, GFP_NOFS);
1286         if (ret < 0)
1287                 goto err_out;
1288         if (barrier)
1289                 blkdev_issue_flush(sb->s_bdev, GFP_NOFS, NULL);
1290 
1291 skip_zeroout:
1292         ext4_lock_group(sb, group);
1293         gdp->bg_flags |= cpu_to_le16(EXT4_BG_INODE_ZEROED);
1294         ext4_group_desc_csum_set(sb, group, gdp);
1295         ext4_unlock_group(sb, group);
1296 
1297         BUFFER_TRACE(group_desc_bh,
1298                      "call ext4_handle_dirty_metadata");
1299         ret = ext4_handle_dirty_metadata(handle, NULL,
1300                                          group_desc_bh);
1301 
1302 err_out:
1303         up_write(&grp->alloc_sem);
1304         ext4_journal_stop(handle);
1305 out:
1306         return ret;
1307 }
1308 

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