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Linux/fs/ext2/inode.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  *  linux/fs/ext2/inode.c
  4  *
  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)
  9  *
 10  *  from
 11  *
 12  *  linux/fs/minix/inode.c
 13  *
 14  *  Copyright (C) 1991, 1992  Linus Torvalds
 15  *
 16  *  Goal-directed block allocation by Stephen Tweedie
 17  *      (sct@dcs.ed.ac.uk), 1993, 1998
 18  *  Big-endian to little-endian byte-swapping/bitmaps by
 19  *        David S. Miller (davem@caip.rutgers.edu), 1995
 20  *  64-bit file support on 64-bit platforms by Jakub Jelinek
 21  *      (jj@sunsite.ms.mff.cuni.cz)
 22  *
 23  *  Assorted race fixes, rewrite of ext2_get_block() by Al Viro, 2000
 24  */
 25 
 26 #include <linux/time.h>
 27 #include <linux/highuid.h>
 28 #include <linux/pagemap.h>
 29 #include <linux/dax.h>
 30 #include <linux/blkdev.h>
 31 #include <linux/quotaops.h>
 32 #include <linux/writeback.h>
 33 #include <linux/buffer_head.h>
 34 #include <linux/mpage.h>
 35 #include <linux/fiemap.h>
 36 #include <linux/iomap.h>
 37 #include <linux/namei.h>
 38 #include <linux/uio.h>
 39 #include "ext2.h"
 40 #include "acl.h"
 41 #include "xattr.h"
 42 
 43 static int __ext2_write_inode(struct inode *inode, int do_sync);
 44 
 45 /*
 46  * Test whether an inode is a fast symlink.
 47  */
 48 static inline int ext2_inode_is_fast_symlink(struct inode *inode)
 49 {
 50         int ea_blocks = EXT2_I(inode)->i_file_acl ?
 51                 (inode->i_sb->s_blocksize >> 9) : 0;
 52 
 53         return (S_ISLNK(inode->i_mode) &&
 54                 inode->i_blocks - ea_blocks == 0);
 55 }
 56 
 57 static void ext2_truncate_blocks(struct inode *inode, loff_t offset);
 58 
 59 static void ext2_write_failed(struct address_space *mapping, loff_t to)
 60 {
 61         struct inode *inode = mapping->host;
 62 
 63         if (to > inode->i_size) {
 64                 truncate_pagecache(inode, inode->i_size);
 65                 ext2_truncate_blocks(inode, inode->i_size);
 66         }
 67 }
 68 
 69 /*
 70  * Called at the last iput() if i_nlink is zero.
 71  */
 72 void ext2_evict_inode(struct inode * inode)
 73 {
 74         struct ext2_block_alloc_info *rsv;
 75         int want_delete = 0;
 76 
 77         if (!inode->i_nlink && !is_bad_inode(inode)) {
 78                 want_delete = 1;
 79                 dquot_initialize(inode);
 80         } else {
 81                 dquot_drop(inode);
 82         }
 83 
 84         truncate_inode_pages_final(&inode->i_data);
 85 
 86         if (want_delete) {
 87                 sb_start_intwrite(inode->i_sb);
 88                 /* set dtime */
 89                 EXT2_I(inode)->i_dtime  = ktime_get_real_seconds();
 90                 mark_inode_dirty(inode);
 91                 __ext2_write_inode(inode, inode_needs_sync(inode));
 92                 /* truncate to 0 */
 93                 inode->i_size = 0;
 94                 if (inode->i_blocks)
 95                         ext2_truncate_blocks(inode, 0);
 96                 ext2_xattr_delete_inode(inode);
 97         }
 98 
 99         invalidate_inode_buffers(inode);
100         clear_inode(inode);
101 
102         ext2_discard_reservation(inode);
103         rsv = EXT2_I(inode)->i_block_alloc_info;
104         EXT2_I(inode)->i_block_alloc_info = NULL;
105         if (unlikely(rsv))
106                 kfree(rsv);
107 
108         if (want_delete) {
109                 ext2_free_inode(inode);
110                 sb_end_intwrite(inode->i_sb);
111         }
112 }
113 
114 typedef struct {
115         __le32  *p;
116         __le32  key;
117         struct buffer_head *bh;
118 } Indirect;
119 
120 static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
121 {
122         p->key = *(p->p = v);
123         p->bh = bh;
124 }
125 
126 static inline int verify_chain(Indirect *from, Indirect *to)
127 {
128         while (from <= to && from->key == *from->p)
129                 from++;
130         return (from > to);
131 }
132 
133 /**
134  *      ext2_block_to_path - parse the block number into array of offsets
135  *      @inode: inode in question (we are only interested in its superblock)
136  *      @i_block: block number to be parsed
137  *      @offsets: array to store the offsets in
138  *      @boundary: set this non-zero if the referred-to block is likely to be
139  *             followed (on disk) by an indirect block.
140  *      To store the locations of file's data ext2 uses a data structure common
141  *      for UNIX filesystems - tree of pointers anchored in the inode, with
142  *      data blocks at leaves and indirect blocks in intermediate nodes.
143  *      This function translates the block number into path in that tree -
144  *      return value is the path length and @offsets[n] is the offset of
145  *      pointer to (n+1)th node in the nth one. If @block is out of range
146  *      (negative or too large) warning is printed and zero returned.
147  *
148  *      Note: function doesn't find node addresses, so no IO is needed. All
149  *      we need to know is the capacity of indirect blocks (taken from the
150  *      inode->i_sb).
151  */
152 
153 /*
154  * Portability note: the last comparison (check that we fit into triple
155  * indirect block) is spelled differently, because otherwise on an
156  * architecture with 32-bit longs and 8Kb pages we might get into trouble
157  * if our filesystem had 8Kb blocks. We might use long long, but that would
158  * kill us on x86. Oh, well, at least the sign propagation does not matter -
159  * i_block would have to be negative in the very beginning, so we would not
160  * get there at all.
161  */
162 
163 static int ext2_block_to_path(struct inode *inode,
164                         long i_block, int offsets[4], int *boundary)
165 {
166         int ptrs = EXT2_ADDR_PER_BLOCK(inode->i_sb);
167         int ptrs_bits = EXT2_ADDR_PER_BLOCK_BITS(inode->i_sb);
168         const long direct_blocks = EXT2_NDIR_BLOCKS,
169                 indirect_blocks = ptrs,
170                 double_blocks = (1 << (ptrs_bits * 2));
171         int n = 0;
172         int final = 0;
173 
174         if (i_block < 0) {
175                 ext2_msg(inode->i_sb, KERN_WARNING,
176                         "warning: %s: block < 0", __func__);
177         } else if (i_block < direct_blocks) {
178                 offsets[n++] = i_block;
179                 final = direct_blocks;
180         } else if ( (i_block -= direct_blocks) < indirect_blocks) {
181                 offsets[n++] = EXT2_IND_BLOCK;
182                 offsets[n++] = i_block;
183                 final = ptrs;
184         } else if ((i_block -= indirect_blocks) < double_blocks) {
185                 offsets[n++] = EXT2_DIND_BLOCK;
186                 offsets[n++] = i_block >> ptrs_bits;
187                 offsets[n++] = i_block & (ptrs - 1);
188                 final = ptrs;
189         } else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
190                 offsets[n++] = EXT2_TIND_BLOCK;
191                 offsets[n++] = i_block >> (ptrs_bits * 2);
192                 offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
193                 offsets[n++] = i_block & (ptrs - 1);
194                 final = ptrs;
195         } else {
196                 ext2_msg(inode->i_sb, KERN_WARNING,
197                         "warning: %s: block is too big", __func__);
198         }
199         if (boundary)
200                 *boundary = final - 1 - (i_block & (ptrs - 1));
201 
202         return n;
203 }
204 
205 /**
206  *      ext2_get_branch - read the chain of indirect blocks leading to data
207  *      @inode: inode in question
208  *      @depth: depth of the chain (1 - direct pointer, etc.)
209  *      @offsets: offsets of pointers in inode/indirect blocks
210  *      @chain: place to store the result
211  *      @err: here we store the error value
212  *
213  *      Function fills the array of triples <key, p, bh> and returns %NULL
214  *      if everything went OK or the pointer to the last filled triple
215  *      (incomplete one) otherwise. Upon the return chain[i].key contains
216  *      the number of (i+1)-th block in the chain (as it is stored in memory,
217  *      i.e. little-endian 32-bit), chain[i].p contains the address of that
218  *      number (it points into struct inode for i==0 and into the bh->b_data
219  *      for i>0) and chain[i].bh points to the buffer_head of i-th indirect
220  *      block for i>0 and NULL for i==0. In other words, it holds the block
221  *      numbers of the chain, addresses they were taken from (and where we can
222  *      verify that chain did not change) and buffer_heads hosting these
223  *      numbers.
224  *
225  *      Function stops when it stumbles upon zero pointer (absent block)
226  *              (pointer to last triple returned, *@err == 0)
227  *      or when it gets an IO error reading an indirect block
228  *              (ditto, *@err == -EIO)
229  *      or when it notices that chain had been changed while it was reading
230  *              (ditto, *@err == -EAGAIN)
231  *      or when it reads all @depth-1 indirect blocks successfully and finds
232  *      the whole chain, all way to the data (returns %NULL, *err == 0).
233  */
234 static Indirect *ext2_get_branch(struct inode *inode,
235                                  int depth,
236                                  int *offsets,
237                                  Indirect chain[4],
238                                  int *err)
239 {
240         struct super_block *sb = inode->i_sb;
241         Indirect *p = chain;
242         struct buffer_head *bh;
243 
244         *err = 0;
245         /* i_data is not going away, no lock needed */
246         add_chain (chain, NULL, EXT2_I(inode)->i_data + *offsets);
247         if (!p->key)
248                 goto no_block;
249         while (--depth) {
250                 bh = sb_bread(sb, le32_to_cpu(p->key));
251                 if (!bh)
252                         goto failure;
253                 read_lock(&EXT2_I(inode)->i_meta_lock);
254                 if (!verify_chain(chain, p))
255                         goto changed;
256                 add_chain(++p, bh, (__le32*)bh->b_data + *++offsets);
257                 read_unlock(&EXT2_I(inode)->i_meta_lock);
258                 if (!p->key)
259                         goto no_block;
260         }
261         return NULL;
262 
263 changed:
264         read_unlock(&EXT2_I(inode)->i_meta_lock);
265         brelse(bh);
266         *err = -EAGAIN;
267         goto no_block;
268 failure:
269         *err = -EIO;
270 no_block:
271         return p;
272 }
273 
274 /**
275  *      ext2_find_near - find a place for allocation with sufficient locality
276  *      @inode: owner
277  *      @ind: descriptor of indirect block.
278  *
279  *      This function returns the preferred place for block allocation.
280  *      It is used when heuristic for sequential allocation fails.
281  *      Rules are:
282  *        + if there is a block to the left of our position - allocate near it.
283  *        + if pointer will live in indirect block - allocate near that block.
284  *        + if pointer will live in inode - allocate in the same cylinder group.
285  *
286  * In the latter case we colour the starting block by the callers PID to
287  * prevent it from clashing with concurrent allocations for a different inode
288  * in the same block group.   The PID is used here so that functionally related
289  * files will be close-by on-disk.
290  *
291  *      Caller must make sure that @ind is valid and will stay that way.
292  */
293 
294 static ext2_fsblk_t ext2_find_near(struct inode *inode, Indirect *ind)
295 {
296         struct ext2_inode_info *ei = EXT2_I(inode);
297         __le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
298         __le32 *p;
299         ext2_fsblk_t bg_start;
300         ext2_fsblk_t colour;
301 
302         /* Try to find previous block */
303         for (p = ind->p - 1; p >= start; p--)
304                 if (*p)
305                         return le32_to_cpu(*p);
306 
307         /* No such thing, so let's try location of indirect block */
308         if (ind->bh)
309                 return ind->bh->b_blocknr;
310 
311         /*
312          * It is going to be referred from inode itself? OK, just put it into
313          * the same cylinder group then.
314          */
315         bg_start = ext2_group_first_block_no(inode->i_sb, ei->i_block_group);
316         colour = (current->pid % 16) *
317                         (EXT2_BLOCKS_PER_GROUP(inode->i_sb) / 16);
318         return bg_start + colour;
319 }
320 
321 /**
322  *      ext2_find_goal - find a preferred place for allocation.
323  *      @inode: owner
324  *      @block:  block we want
325  *      @partial: pointer to the last triple within a chain
326  *
327  *      Returns preferred place for a block (the goal).
328  */
329 
330 static inline ext2_fsblk_t ext2_find_goal(struct inode *inode, long block,
331                                           Indirect *partial)
332 {
333         struct ext2_block_alloc_info *block_i;
334 
335         block_i = EXT2_I(inode)->i_block_alloc_info;
336 
337         /*
338          * try the heuristic for sequential allocation,
339          * failing that at least try to get decent locality.
340          */
341         if (block_i && (block == block_i->last_alloc_logical_block + 1)
342                 && (block_i->last_alloc_physical_block != 0)) {
343                 return block_i->last_alloc_physical_block + 1;
344         }
345 
346         return ext2_find_near(inode, partial);
347 }
348 
349 /**
350  *      ext2_blks_to_allocate: Look up the block map and count the number
351  *      of direct blocks need to be allocated for the given branch.
352  *
353  *      @branch: chain of indirect blocks
354  *      @k: number of blocks need for indirect blocks
355  *      @blks: number of data blocks to be mapped.
356  *      @blocks_to_boundary:  the offset in the indirect block
357  *
358  *      return the number of direct blocks to allocate.
359  */
360 static int
361 ext2_blks_to_allocate(Indirect * branch, int k, unsigned long blks,
362                 int blocks_to_boundary)
363 {
364         unsigned long count = 0;
365 
366         /*
367          * Simple case, [t,d]Indirect block(s) has not allocated yet
368          * then it's clear blocks on that path have not allocated
369          */
370         if (k > 0) {
371                 /* right now don't hanel cross boundary allocation */
372                 if (blks < blocks_to_boundary + 1)
373                         count += blks;
374                 else
375                         count += blocks_to_boundary + 1;
376                 return count;
377         }
378 
379         count++;
380         while (count < blks && count <= blocks_to_boundary
381                 && le32_to_cpu(*(branch[0].p + count)) == 0) {
382                 count++;
383         }
384         return count;
385 }
386 
387 /**
388  *      ext2_alloc_blocks: multiple allocate blocks needed for a branch
389  *      @indirect_blks: the number of blocks need to allocate for indirect
390  *                      blocks
391  *      @blks: the number of blocks need to allocate for direct blocks
392  *      @new_blocks: on return it will store the new block numbers for
393  *      the indirect blocks(if needed) and the first direct block,
394  */
395 static int ext2_alloc_blocks(struct inode *inode,
396                         ext2_fsblk_t goal, int indirect_blks, int blks,
397                         ext2_fsblk_t new_blocks[4], int *err)
398 {
399         int target, i;
400         unsigned long count = 0;
401         int index = 0;
402         ext2_fsblk_t current_block = 0;
403         int ret = 0;
404 
405         /*
406          * Here we try to allocate the requested multiple blocks at once,
407          * on a best-effort basis.
408          * To build a branch, we should allocate blocks for
409          * the indirect blocks(if not allocated yet), and at least
410          * the first direct block of this branch.  That's the
411          * minimum number of blocks need to allocate(required)
412          */
413         target = blks + indirect_blks;
414 
415         while (1) {
416                 count = target;
417                 /* allocating blocks for indirect blocks and direct blocks */
418                 current_block = ext2_new_blocks(inode,goal,&count,err);
419                 if (*err)
420                         goto failed_out;
421 
422                 target -= count;
423                 /* allocate blocks for indirect blocks */
424                 while (index < indirect_blks && count) {
425                         new_blocks[index++] = current_block++;
426                         count--;
427                 }
428 
429                 if (count > 0)
430                         break;
431         }
432 
433         /* save the new block number for the first direct block */
434         new_blocks[index] = current_block;
435 
436         /* total number of blocks allocated for direct blocks */
437         ret = count;
438         *err = 0;
439         return ret;
440 failed_out:
441         for (i = 0; i <index; i++)
442                 ext2_free_blocks(inode, new_blocks[i], 1);
443         if (index)
444                 mark_inode_dirty(inode);
445         return ret;
446 }
447 
448 /**
449  *      ext2_alloc_branch - allocate and set up a chain of blocks.
450  *      @inode: owner
451  *      @indirect_blks: depth of the chain (number of blocks to allocate)
452  *      @blks: number of allocated direct blocks
453  *      @goal: preferred place for allocation
454  *      @offsets: offsets (in the blocks) to store the pointers to next.
455  *      @branch: place to store the chain in.
456  *
457  *      This function allocates @num blocks, zeroes out all but the last one,
458  *      links them into chain and (if we are synchronous) writes them to disk.
459  *      In other words, it prepares a branch that can be spliced onto the
460  *      inode. It stores the information about that chain in the branch[], in
461  *      the same format as ext2_get_branch() would do. We are calling it after
462  *      we had read the existing part of chain and partial points to the last
463  *      triple of that (one with zero ->key). Upon the exit we have the same
464  *      picture as after the successful ext2_get_block(), except that in one
465  *      place chain is disconnected - *branch->p is still zero (we did not
466  *      set the last link), but branch->key contains the number that should
467  *      be placed into *branch->p to fill that gap.
468  *
469  *      If allocation fails we free all blocks we've allocated (and forget
470  *      their buffer_heads) and return the error value the from failed
471  *      ext2_alloc_block() (normally -ENOSPC). Otherwise we set the chain
472  *      as described above and return 0.
473  */
474 
475 static int ext2_alloc_branch(struct inode *inode,
476                         int indirect_blks, int *blks, ext2_fsblk_t goal,
477                         int *offsets, Indirect *branch)
478 {
479         int blocksize = inode->i_sb->s_blocksize;
480         int i, n = 0;
481         int err = 0;
482         struct buffer_head *bh;
483         int num;
484         ext2_fsblk_t new_blocks[4];
485         ext2_fsblk_t current_block;
486 
487         num = ext2_alloc_blocks(inode, goal, indirect_blks,
488                                 *blks, new_blocks, &err);
489         if (err)
490                 return err;
491 
492         branch[0].key = cpu_to_le32(new_blocks[0]);
493         /*
494          * metadata blocks and data blocks are allocated.
495          */
496         for (n = 1; n <= indirect_blks;  n++) {
497                 /*
498                  * Get buffer_head for parent block, zero it out
499                  * and set the pointer to new one, then send
500                  * parent to disk.
501                  */
502                 bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
503                 if (unlikely(!bh)) {
504                         err = -ENOMEM;
505                         goto failed;
506                 }
507                 branch[n].bh = bh;
508                 lock_buffer(bh);
509                 memset(bh->b_data, 0, blocksize);
510                 branch[n].p = (__le32 *) bh->b_data + offsets[n];
511                 branch[n].key = cpu_to_le32(new_blocks[n]);
512                 *branch[n].p = branch[n].key;
513                 if ( n == indirect_blks) {
514                         current_block = new_blocks[n];
515                         /*
516                          * End of chain, update the last new metablock of
517                          * the chain to point to the new allocated
518                          * data blocks numbers
519                          */
520                         for (i=1; i < num; i++)
521                                 *(branch[n].p + i) = cpu_to_le32(++current_block);
522                 }
523                 set_buffer_uptodate(bh);
524                 unlock_buffer(bh);
525                 mark_buffer_dirty_inode(bh, inode);
526                 /* We used to sync bh here if IS_SYNC(inode).
527                  * But we now rely upon generic_write_sync()
528                  * and b_inode_buffers.  But not for directories.
529                  */
530                 if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
531                         sync_dirty_buffer(bh);
532         }
533         *blks = num;
534         return err;
535 
536 failed:
537         for (i = 1; i < n; i++)
538                 bforget(branch[i].bh);
539         for (i = 0; i < indirect_blks; i++)
540                 ext2_free_blocks(inode, new_blocks[i], 1);
541         ext2_free_blocks(inode, new_blocks[i], num);
542         return err;
543 }
544 
545 /**
546  * ext2_splice_branch - splice the allocated branch onto inode.
547  * @inode: owner
548  * @block: (logical) number of block we are adding
549  * @where: location of missing link
550  * @num:   number of indirect blocks we are adding
551  * @blks:  number of direct blocks we are adding
552  *
553  * This function fills the missing link and does all housekeeping needed in
554  * inode (->i_blocks, etc.). In case of success we end up with the full
555  * chain to new block and return 0.
556  */
557 static void ext2_splice_branch(struct inode *inode,
558                         long block, Indirect *where, int num, int blks)
559 {
560         int i;
561         struct ext2_block_alloc_info *block_i;
562         ext2_fsblk_t current_block;
563 
564         block_i = EXT2_I(inode)->i_block_alloc_info;
565 
566         /* XXX LOCKING probably should have i_meta_lock ?*/
567         /* That's it */
568 
569         *where->p = where->key;
570 
571         /*
572          * Update the host buffer_head or inode to point to more just allocated
573          * direct blocks blocks
574          */
575         if (num == 0 && blks > 1) {
576                 current_block = le32_to_cpu(where->key) + 1;
577                 for (i = 1; i < blks; i++)
578                         *(where->p + i ) = cpu_to_le32(current_block++);
579         }
580 
581         /*
582          * update the most recently allocated logical & physical block
583          * in i_block_alloc_info, to assist find the proper goal block for next
584          * allocation
585          */
586         if (block_i) {
587                 block_i->last_alloc_logical_block = block + blks - 1;
588                 block_i->last_alloc_physical_block =
589                                 le32_to_cpu(where[num].key) + blks - 1;
590         }
591 
592         /* We are done with atomic stuff, now do the rest of housekeeping */
593 
594         /* had we spliced it onto indirect block? */
595         if (where->bh)
596                 mark_buffer_dirty_inode(where->bh, inode);
597 
598         inode->i_ctime = current_time(inode);
599         mark_inode_dirty(inode);
600 }
601 
602 /*
603  * Allocation strategy is simple: if we have to allocate something, we will
604  * have to go the whole way to leaf. So let's do it before attaching anything
605  * to tree, set linkage between the newborn blocks, write them if sync is
606  * required, recheck the path, free and repeat if check fails, otherwise
607  * set the last missing link (that will protect us from any truncate-generated
608  * removals - all blocks on the path are immune now) and possibly force the
609  * write on the parent block.
610  * That has a nice additional property: no special recovery from the failed
611  * allocations is needed - we simply release blocks and do not touch anything
612  * reachable from inode.
613  *
614  * `handle' can be NULL if create == 0.
615  *
616  * return > 0, # of blocks mapped or allocated.
617  * return = 0, if plain lookup failed.
618  * return < 0, error case.
619  */
620 static int ext2_get_blocks(struct inode *inode,
621                            sector_t iblock, unsigned long maxblocks,
622                            u32 *bno, bool *new, bool *boundary,
623                            int create)
624 {
625         int err;
626         int offsets[4];
627         Indirect chain[4];
628         Indirect *partial;
629         ext2_fsblk_t goal;
630         int indirect_blks;
631         int blocks_to_boundary = 0;
632         int depth;
633         struct ext2_inode_info *ei = EXT2_I(inode);
634         int count = 0;
635         ext2_fsblk_t first_block = 0;
636 
637         BUG_ON(maxblocks == 0);
638 
639         depth = ext2_block_to_path(inode,iblock,offsets,&blocks_to_boundary);
640 
641         if (depth == 0)
642                 return -EIO;
643 
644         partial = ext2_get_branch(inode, depth, offsets, chain, &err);
645         /* Simplest case - block found, no allocation needed */
646         if (!partial) {
647                 first_block = le32_to_cpu(chain[depth - 1].key);
648                 count++;
649                 /*map more blocks*/
650                 while (count < maxblocks && count <= blocks_to_boundary) {
651                         ext2_fsblk_t blk;
652 
653                         if (!verify_chain(chain, chain + depth - 1)) {
654                                 /*
655                                  * Indirect block might be removed by
656                                  * truncate while we were reading it.
657                                  * Handling of that case: forget what we've
658                                  * got now, go to reread.
659                                  */
660                                 err = -EAGAIN;
661                                 count = 0;
662                                 partial = chain + depth - 1;
663                                 break;
664                         }
665                         blk = le32_to_cpu(*(chain[depth-1].p + count));
666                         if (blk == first_block + count)
667                                 count++;
668                         else
669                                 break;
670                 }
671                 if (err != -EAGAIN)
672                         goto got_it;
673         }
674 
675         /* Next simple case - plain lookup or failed read of indirect block */
676         if (!create || err == -EIO)
677                 goto cleanup;
678 
679         mutex_lock(&ei->truncate_mutex);
680         /*
681          * If the indirect block is missing while we are reading
682          * the chain(ext2_get_branch() returns -EAGAIN err), or
683          * if the chain has been changed after we grab the semaphore,
684          * (either because another process truncated this branch, or
685          * another get_block allocated this branch) re-grab the chain to see if
686          * the request block has been allocated or not.
687          *
688          * Since we already block the truncate/other get_block
689          * at this point, we will have the current copy of the chain when we
690          * splice the branch into the tree.
691          */
692         if (err == -EAGAIN || !verify_chain(chain, partial)) {
693                 while (partial > chain) {
694                         brelse(partial->bh);
695                         partial--;
696                 }
697                 partial = ext2_get_branch(inode, depth, offsets, chain, &err);
698                 if (!partial) {
699                         count++;
700                         mutex_unlock(&ei->truncate_mutex);
701                         goto got_it;
702                 }
703 
704                 if (err) {
705                         mutex_unlock(&ei->truncate_mutex);
706                         goto cleanup;
707                 }
708         }
709 
710         /*
711          * Okay, we need to do block allocation.  Lazily initialize the block
712          * allocation info here if necessary
713         */
714         if (S_ISREG(inode->i_mode) && (!ei->i_block_alloc_info))
715                 ext2_init_block_alloc_info(inode);
716 
717         goal = ext2_find_goal(inode, iblock, partial);
718 
719         /* the number of blocks need to allocate for [d,t]indirect blocks */
720         indirect_blks = (chain + depth) - partial - 1;
721         /*
722          * Next look up the indirect map to count the total number of
723          * direct blocks to allocate for this branch.
724          */
725         count = ext2_blks_to_allocate(partial, indirect_blks,
726                                         maxblocks, blocks_to_boundary);
727         /*
728          * XXX ???? Block out ext2_truncate while we alter the tree
729          */
730         err = ext2_alloc_branch(inode, indirect_blks, &count, goal,
731                                 offsets + (partial - chain), partial);
732 
733         if (err) {
734                 mutex_unlock(&ei->truncate_mutex);
735                 goto cleanup;
736         }
737 
738         if (IS_DAX(inode)) {
739                 /*
740                  * We must unmap blocks before zeroing so that writeback cannot
741                  * overwrite zeros with stale data from block device page cache.
742                  */
743                 clean_bdev_aliases(inode->i_sb->s_bdev,
744                                    le32_to_cpu(chain[depth-1].key),
745                                    count);
746                 /*
747                  * block must be initialised before we put it in the tree
748                  * so that it's not found by another thread before it's
749                  * initialised
750                  */
751                 err = sb_issue_zeroout(inode->i_sb,
752                                 le32_to_cpu(chain[depth-1].key), count,
753                                 GFP_NOFS);
754                 if (err) {
755                         mutex_unlock(&ei->truncate_mutex);
756                         goto cleanup;
757                 }
758         }
759         *new = true;
760 
761         ext2_splice_branch(inode, iblock, partial, indirect_blks, count);
762         mutex_unlock(&ei->truncate_mutex);
763 got_it:
764         if (count > blocks_to_boundary)
765                 *boundary = true;
766         err = count;
767         /* Clean up and exit */
768         partial = chain + depth - 1;    /* the whole chain */
769 cleanup:
770         while (partial > chain) {
771                 brelse(partial->bh);
772                 partial--;
773         }
774         if (err > 0)
775                 *bno = le32_to_cpu(chain[depth-1].key);
776         return err;
777 }
778 
779 int ext2_get_block(struct inode *inode, sector_t iblock,
780                 struct buffer_head *bh_result, int create)
781 {
782         unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
783         bool new = false, boundary = false;
784         u32 bno;
785         int ret;
786 
787         ret = ext2_get_blocks(inode, iblock, max_blocks, &bno, &new, &boundary,
788                         create);
789         if (ret <= 0)
790                 return ret;
791 
792         map_bh(bh_result, inode->i_sb, bno);
793         bh_result->b_size = (ret << inode->i_blkbits);
794         if (new)
795                 set_buffer_new(bh_result);
796         if (boundary)
797                 set_buffer_boundary(bh_result);
798         return 0;
799 
800 }
801 
802 #ifdef CONFIG_FS_DAX
803 static int ext2_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
804                 unsigned flags, struct iomap *iomap, struct iomap *srcmap)
805 {
806         unsigned int blkbits = inode->i_blkbits;
807         unsigned long first_block = offset >> blkbits;
808         unsigned long max_blocks = (length + (1 << blkbits) - 1) >> blkbits;
809         struct ext2_sb_info *sbi = EXT2_SB(inode->i_sb);
810         bool new = false, boundary = false;
811         u32 bno;
812         int ret;
813 
814         ret = ext2_get_blocks(inode, first_block, max_blocks,
815                         &bno, &new, &boundary, flags & IOMAP_WRITE);
816         if (ret < 0)
817                 return ret;
818 
819         iomap->flags = 0;
820         iomap->bdev = inode->i_sb->s_bdev;
821         iomap->offset = (u64)first_block << blkbits;
822         iomap->dax_dev = sbi->s_daxdev;
823 
824         if (ret == 0) {
825                 iomap->type = IOMAP_HOLE;
826                 iomap->addr = IOMAP_NULL_ADDR;
827                 iomap->length = 1 << blkbits;
828         } else {
829                 iomap->type = IOMAP_MAPPED;
830                 iomap->addr = (u64)bno << blkbits;
831                 iomap->length = (u64)ret << blkbits;
832                 iomap->flags |= IOMAP_F_MERGED;
833         }
834 
835         if (new)
836                 iomap->flags |= IOMAP_F_NEW;
837         return 0;
838 }
839 
840 static int
841 ext2_iomap_end(struct inode *inode, loff_t offset, loff_t length,
842                 ssize_t written, unsigned flags, struct iomap *iomap)
843 {
844         if (iomap->type == IOMAP_MAPPED &&
845             written < length &&
846             (flags & IOMAP_WRITE))
847                 ext2_write_failed(inode->i_mapping, offset + length);
848         return 0;
849 }
850 
851 const struct iomap_ops ext2_iomap_ops = {
852         .iomap_begin            = ext2_iomap_begin,
853         .iomap_end              = ext2_iomap_end,
854 };
855 #else
856 /* Define empty ops for !CONFIG_FS_DAX case to avoid ugly ifdefs */
857 const struct iomap_ops ext2_iomap_ops;
858 #endif /* CONFIG_FS_DAX */
859 
860 int ext2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
861                 u64 start, u64 len)
862 {
863         return generic_block_fiemap(inode, fieinfo, start, len,
864                                     ext2_get_block);
865 }
866 
867 static int ext2_writepage(struct page *page, struct writeback_control *wbc)
868 {
869         return block_write_full_page(page, ext2_get_block, wbc);
870 }
871 
872 static int ext2_readpage(struct file *file, struct page *page)
873 {
874         return mpage_readpage(page, ext2_get_block);
875 }
876 
877 static void ext2_readahead(struct readahead_control *rac)
878 {
879         mpage_readahead(rac, ext2_get_block);
880 }
881 
882 static int
883 ext2_write_begin(struct file *file, struct address_space *mapping,
884                 loff_t pos, unsigned len, unsigned flags,
885                 struct page **pagep, void **fsdata)
886 {
887         int ret;
888 
889         ret = block_write_begin(mapping, pos, len, flags, pagep,
890                                 ext2_get_block);
891         if (ret < 0)
892                 ext2_write_failed(mapping, pos + len);
893         return ret;
894 }
895 
896 static int ext2_write_end(struct file *file, struct address_space *mapping,
897                         loff_t pos, unsigned len, unsigned copied,
898                         struct page *page, void *fsdata)
899 {
900         int ret;
901 
902         ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
903         if (ret < len)
904                 ext2_write_failed(mapping, pos + len);
905         return ret;
906 }
907 
908 static int
909 ext2_nobh_write_begin(struct file *file, struct address_space *mapping,
910                 loff_t pos, unsigned len, unsigned flags,
911                 struct page **pagep, void **fsdata)
912 {
913         int ret;
914 
915         ret = nobh_write_begin(mapping, pos, len, flags, pagep, fsdata,
916                                ext2_get_block);
917         if (ret < 0)
918                 ext2_write_failed(mapping, pos + len);
919         return ret;
920 }
921 
922 static int ext2_nobh_writepage(struct page *page,
923                         struct writeback_control *wbc)
924 {
925         return nobh_writepage(page, ext2_get_block, wbc);
926 }
927 
928 static sector_t ext2_bmap(struct address_space *mapping, sector_t block)
929 {
930         return generic_block_bmap(mapping,block,ext2_get_block);
931 }
932 
933 static ssize_t
934 ext2_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
935 {
936         struct file *file = iocb->ki_filp;
937         struct address_space *mapping = file->f_mapping;
938         struct inode *inode = mapping->host;
939         size_t count = iov_iter_count(iter);
940         loff_t offset = iocb->ki_pos;
941         ssize_t ret;
942 
943         ret = blockdev_direct_IO(iocb, inode, iter, ext2_get_block);
944         if (ret < 0 && iov_iter_rw(iter) == WRITE)
945                 ext2_write_failed(mapping, offset + count);
946         return ret;
947 }
948 
949 static int
950 ext2_writepages(struct address_space *mapping, struct writeback_control *wbc)
951 {
952         return mpage_writepages(mapping, wbc, ext2_get_block);
953 }
954 
955 static int
956 ext2_dax_writepages(struct address_space *mapping, struct writeback_control *wbc)
957 {
958         struct ext2_sb_info *sbi = EXT2_SB(mapping->host->i_sb);
959 
960         return dax_writeback_mapping_range(mapping, sbi->s_daxdev, wbc);
961 }
962 
963 const struct address_space_operations ext2_aops = {
964         .readpage               = ext2_readpage,
965         .readahead              = ext2_readahead,
966         .writepage              = ext2_writepage,
967         .write_begin            = ext2_write_begin,
968         .write_end              = ext2_write_end,
969         .bmap                   = ext2_bmap,
970         .direct_IO              = ext2_direct_IO,
971         .writepages             = ext2_writepages,
972         .migratepage            = buffer_migrate_page,
973         .is_partially_uptodate  = block_is_partially_uptodate,
974         .error_remove_page      = generic_error_remove_page,
975 };
976 
977 const struct address_space_operations ext2_nobh_aops = {
978         .readpage               = ext2_readpage,
979         .readahead              = ext2_readahead,
980         .writepage              = ext2_nobh_writepage,
981         .write_begin            = ext2_nobh_write_begin,
982         .write_end              = nobh_write_end,
983         .bmap                   = ext2_bmap,
984         .direct_IO              = ext2_direct_IO,
985         .writepages             = ext2_writepages,
986         .migratepage            = buffer_migrate_page,
987         .error_remove_page      = generic_error_remove_page,
988 };
989 
990 static const struct address_space_operations ext2_dax_aops = {
991         .writepages             = ext2_dax_writepages,
992         .direct_IO              = noop_direct_IO,
993         .set_page_dirty         = noop_set_page_dirty,
994         .invalidatepage         = noop_invalidatepage,
995 };
996 
997 /*
998  * Probably it should be a library function... search for first non-zero word
999  * or memcmp with zero_page, whatever is better for particular architecture.
1000  * Linus?
1001  */
1002 static inline int all_zeroes(__le32 *p, __le32 *q)
1003 {
1004         while (p < q)
1005                 if (*p++)
1006                         return 0;
1007         return 1;
1008 }
1009 
1010 /**
1011  *      ext2_find_shared - find the indirect blocks for partial truncation.
1012  *      @inode:   inode in question
1013  *      @depth:   depth of the affected branch
1014  *      @offsets: offsets of pointers in that branch (see ext2_block_to_path)
1015  *      @chain:   place to store the pointers to partial indirect blocks
1016  *      @top:     place to the (detached) top of branch
1017  *
1018  *      This is a helper function used by ext2_truncate().
1019  *
1020  *      When we do truncate() we may have to clean the ends of several indirect
1021  *      blocks but leave the blocks themselves alive. Block is partially
1022  *      truncated if some data below the new i_size is referred from it (and
1023  *      it is on the path to the first completely truncated data block, indeed).
1024  *      We have to free the top of that path along with everything to the right
1025  *      of the path. Since no allocation past the truncation point is possible
1026  *      until ext2_truncate() finishes, we may safely do the latter, but top
1027  *      of branch may require special attention - pageout below the truncation
1028  *      point might try to populate it.
1029  *
1030  *      We atomically detach the top of branch from the tree, store the block
1031  *      number of its root in *@top, pointers to buffer_heads of partially
1032  *      truncated blocks - in @chain[].bh and pointers to their last elements
1033  *      that should not be removed - in @chain[].p. Return value is the pointer
1034  *      to last filled element of @chain.
1035  *
1036  *      The work left to caller to do the actual freeing of subtrees:
1037  *              a) free the subtree starting from *@top
1038  *              b) free the subtrees whose roots are stored in
1039  *                      (@chain[i].p+1 .. end of @chain[i].bh->b_data)
1040  *              c) free the subtrees growing from the inode past the @chain[0].p
1041  *                      (no partially truncated stuff there).
1042  */
1043 
1044 static Indirect *ext2_find_shared(struct inode *inode,
1045                                 int depth,
1046                                 int offsets[4],
1047                                 Indirect chain[4],
1048                                 __le32 *top)
1049 {
1050         Indirect *partial, *p;
1051         int k, err;
1052 
1053         *top = 0;
1054         for (k = depth; k > 1 && !offsets[k-1]; k--)
1055                 ;
1056         partial = ext2_get_branch(inode, k, offsets, chain, &err);
1057         if (!partial)
1058                 partial = chain + k-1;
1059         /*
1060          * If the branch acquired continuation since we've looked at it -
1061          * fine, it should all survive and (new) top doesn't belong to us.
1062          */
1063         write_lock(&EXT2_I(inode)->i_meta_lock);
1064         if (!partial->key && *partial->p) {
1065                 write_unlock(&EXT2_I(inode)->i_meta_lock);
1066                 goto no_top;
1067         }
1068         for (p=partial; p>chain && all_zeroes((__le32*)p->bh->b_data,p->p); p--)
1069                 ;
1070         /*
1071          * OK, we've found the last block that must survive. The rest of our
1072          * branch should be detached before unlocking. However, if that rest
1073          * of branch is all ours and does not grow immediately from the inode
1074          * it's easier to cheat and just decrement partial->p.
1075          */
1076         if (p == chain + k - 1 && p > chain) {
1077                 p->p--;
1078         } else {
1079                 *top = *p->p;
1080                 *p->p = 0;
1081         }
1082         write_unlock(&EXT2_I(inode)->i_meta_lock);
1083 
1084         while(partial > p)
1085         {
1086                 brelse(partial->bh);
1087                 partial--;
1088         }
1089 no_top:
1090         return partial;
1091 }
1092 
1093 /**
1094  *      ext2_free_data - free a list of data blocks
1095  *      @inode: inode we are dealing with
1096  *      @p:     array of block numbers
1097  *      @q:     points immediately past the end of array
1098  *
1099  *      We are freeing all blocks referred from that array (numbers are
1100  *      stored as little-endian 32-bit) and updating @inode->i_blocks
1101  *      appropriately.
1102  */
1103 static inline void ext2_free_data(struct inode *inode, __le32 *p, __le32 *q)
1104 {
1105         unsigned long block_to_free = 0, count = 0;
1106         unsigned long nr;
1107 
1108         for ( ; p < q ; p++) {
1109                 nr = le32_to_cpu(*p);
1110                 if (nr) {
1111                         *p = 0;
1112                         /* accumulate blocks to free if they're contiguous */
1113                         if (count == 0)
1114                                 goto free_this;
1115                         else if (block_to_free == nr - count)
1116                                 count++;
1117                         else {
1118                                 ext2_free_blocks (inode, block_to_free, count);
1119                                 mark_inode_dirty(inode);
1120                         free_this:
1121                                 block_to_free = nr;
1122                                 count = 1;
1123                         }
1124                 }
1125         }
1126         if (count > 0) {
1127                 ext2_free_blocks (inode, block_to_free, count);
1128                 mark_inode_dirty(inode);
1129         }
1130 }
1131 
1132 /**
1133  *      ext2_free_branches - free an array of branches
1134  *      @inode: inode we are dealing with
1135  *      @p:     array of block numbers
1136  *      @q:     pointer immediately past the end of array
1137  *      @depth: depth of the branches to free
1138  *
1139  *      We are freeing all blocks referred from these branches (numbers are
1140  *      stored as little-endian 32-bit) and updating @inode->i_blocks
1141  *      appropriately.
1142  */
1143 static void ext2_free_branches(struct inode *inode, __le32 *p, __le32 *q, int depth)
1144 {
1145         struct buffer_head * bh;
1146         unsigned long nr;
1147 
1148         if (depth--) {
1149                 int addr_per_block = EXT2_ADDR_PER_BLOCK(inode->i_sb);
1150                 for ( ; p < q ; p++) {
1151                         nr = le32_to_cpu(*p);
1152                         if (!nr)
1153                                 continue;
1154                         *p = 0;
1155                         bh = sb_bread(inode->i_sb, nr);
1156                         /*
1157                          * A read failure? Report error and clear slot
1158                          * (should be rare).
1159                          */ 
1160                         if (!bh) {
1161                                 ext2_error(inode->i_sb, "ext2_free_branches",
1162                                         "Read failure, inode=%ld, block=%ld",
1163                                         inode->i_ino, nr);
1164                                 continue;
1165                         }
1166                         ext2_free_branches(inode,
1167                                            (__le32*)bh->b_data,
1168                                            (__le32*)bh->b_data + addr_per_block,
1169                                            depth);
1170                         bforget(bh);
1171                         ext2_free_blocks(inode, nr, 1);
1172                         mark_inode_dirty(inode);
1173                 }
1174         } else
1175                 ext2_free_data(inode, p, q);
1176 }
1177 
1178 /* dax_sem must be held when calling this function */
1179 static void __ext2_truncate_blocks(struct inode *inode, loff_t offset)
1180 {
1181         __le32 *i_data = EXT2_I(inode)->i_data;
1182         struct ext2_inode_info *ei = EXT2_I(inode);
1183         int addr_per_block = EXT2_ADDR_PER_BLOCK(inode->i_sb);
1184         int offsets[4];
1185         Indirect chain[4];
1186         Indirect *partial;
1187         __le32 nr = 0;
1188         int n;
1189         long iblock;
1190         unsigned blocksize;
1191         blocksize = inode->i_sb->s_blocksize;
1192         iblock = (offset + blocksize-1) >> EXT2_BLOCK_SIZE_BITS(inode->i_sb);
1193 
1194 #ifdef CONFIG_FS_DAX
1195         WARN_ON(!rwsem_is_locked(&ei->dax_sem));
1196 #endif
1197 
1198         n = ext2_block_to_path(inode, iblock, offsets, NULL);
1199         if (n == 0)
1200                 return;
1201 
1202         /*
1203          * From here we block out all ext2_get_block() callers who want to
1204          * modify the block allocation tree.
1205          */
1206         mutex_lock(&ei->truncate_mutex);
1207 
1208         if (n == 1) {
1209                 ext2_free_data(inode, i_data+offsets[0],
1210                                         i_data + EXT2_NDIR_BLOCKS);
1211                 goto do_indirects;
1212         }
1213 
1214         partial = ext2_find_shared(inode, n, offsets, chain, &nr);
1215         /* Kill the top of shared branch (already detached) */
1216         if (nr) {
1217                 if (partial == chain)
1218                         mark_inode_dirty(inode);
1219                 else
1220                         mark_buffer_dirty_inode(partial->bh, inode);
1221                 ext2_free_branches(inode, &nr, &nr+1, (chain+n-1) - partial);
1222         }
1223         /* Clear the ends of indirect blocks on the shared branch */
1224         while (partial > chain) {
1225                 ext2_free_branches(inode,
1226                                    partial->p + 1,
1227                                    (__le32*)partial->bh->b_data+addr_per_block,
1228                                    (chain+n-1) - partial);
1229                 mark_buffer_dirty_inode(partial->bh, inode);
1230                 brelse (partial->bh);
1231                 partial--;
1232         }
1233 do_indirects:
1234         /* Kill the remaining (whole) subtrees */
1235         switch (offsets[0]) {
1236                 default:
1237                         nr = i_data[EXT2_IND_BLOCK];
1238                         if (nr) {
1239                                 i_data[EXT2_IND_BLOCK] = 0;
1240                                 mark_inode_dirty(inode);
1241                                 ext2_free_branches(inode, &nr, &nr+1, 1);
1242                         }
1243                         fallthrough;
1244                 case EXT2_IND_BLOCK:
1245                         nr = i_data[EXT2_DIND_BLOCK];
1246                         if (nr) {
1247                                 i_data[EXT2_DIND_BLOCK] = 0;
1248                                 mark_inode_dirty(inode);
1249                                 ext2_free_branches(inode, &nr, &nr+1, 2);
1250                         }
1251                         fallthrough;
1252                 case EXT2_DIND_BLOCK:
1253                         nr = i_data[EXT2_TIND_BLOCK];
1254                         if (nr) {
1255                                 i_data[EXT2_TIND_BLOCK] = 0;
1256                                 mark_inode_dirty(inode);
1257                                 ext2_free_branches(inode, &nr, &nr+1, 3);
1258                         }
1259                         break;
1260                 case EXT2_TIND_BLOCK:
1261                         ;
1262         }
1263 
1264         ext2_discard_reservation(inode);
1265 
1266         mutex_unlock(&ei->truncate_mutex);
1267 }
1268 
1269 static void ext2_truncate_blocks(struct inode *inode, loff_t offset)
1270 {
1271         if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
1272             S_ISLNK(inode->i_mode)))
1273                 return;
1274         if (ext2_inode_is_fast_symlink(inode))
1275                 return;
1276 
1277         dax_sem_down_write(EXT2_I(inode));
1278         __ext2_truncate_blocks(inode, offset);
1279         dax_sem_up_write(EXT2_I(inode));
1280 }
1281 
1282 static int ext2_setsize(struct inode *inode, loff_t newsize)
1283 {
1284         int error;
1285 
1286         if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
1287             S_ISLNK(inode->i_mode)))
1288                 return -EINVAL;
1289         if (ext2_inode_is_fast_symlink(inode))
1290                 return -EINVAL;
1291         if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
1292                 return -EPERM;
1293 
1294         inode_dio_wait(inode);
1295 
1296         if (IS_DAX(inode)) {
1297                 error = iomap_zero_range(inode, newsize,
1298                                          PAGE_ALIGN(newsize) - newsize, NULL,
1299                                          &ext2_iomap_ops);
1300         } else if (test_opt(inode->i_sb, NOBH))
1301                 error = nobh_truncate_page(inode->i_mapping,
1302                                 newsize, ext2_get_block);
1303         else
1304                 error = block_truncate_page(inode->i_mapping,
1305                                 newsize, ext2_get_block);
1306         if (error)
1307                 return error;
1308 
1309         dax_sem_down_write(EXT2_I(inode));
1310         truncate_setsize(inode, newsize);
1311         __ext2_truncate_blocks(inode, newsize);
1312         dax_sem_up_write(EXT2_I(inode));
1313 
1314         inode->i_mtime = inode->i_ctime = current_time(inode);
1315         if (inode_needs_sync(inode)) {
1316                 sync_mapping_buffers(inode->i_mapping);
1317                 sync_inode_metadata(inode, 1);
1318         } else {
1319                 mark_inode_dirty(inode);
1320         }
1321 
1322         return 0;
1323 }
1324 
1325 static struct ext2_inode *ext2_get_inode(struct super_block *sb, ino_t ino,
1326                                         struct buffer_head **p)
1327 {
1328         struct buffer_head * bh;
1329         unsigned long block_group;
1330         unsigned long block;
1331         unsigned long offset;
1332         struct ext2_group_desc * gdp;
1333 
1334         *p = NULL;
1335         if ((ino != EXT2_ROOT_INO && ino < EXT2_FIRST_INO(sb)) ||
1336             ino > le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count))
1337                 goto Einval;
1338 
1339         block_group = (ino - 1) / EXT2_INODES_PER_GROUP(sb);
1340         gdp = ext2_get_group_desc(sb, block_group, NULL);
1341         if (!gdp)
1342                 goto Egdp;
1343         /*
1344          * Figure out the offset within the block group inode table
1345          */
1346         offset = ((ino - 1) % EXT2_INODES_PER_GROUP(sb)) * EXT2_INODE_SIZE(sb);
1347         block = le32_to_cpu(gdp->bg_inode_table) +
1348                 (offset >> EXT2_BLOCK_SIZE_BITS(sb));
1349         if (!(bh = sb_bread(sb, block)))
1350                 goto Eio;
1351 
1352         *p = bh;
1353         offset &= (EXT2_BLOCK_SIZE(sb) - 1);
1354         return (struct ext2_inode *) (bh->b_data + offset);
1355 
1356 Einval:
1357         ext2_error(sb, "ext2_get_inode", "bad inode number: %lu",
1358                    (unsigned long) ino);
1359         return ERR_PTR(-EINVAL);
1360 Eio:
1361         ext2_error(sb, "ext2_get_inode",
1362                    "unable to read inode block - inode=%lu, block=%lu",
1363                    (unsigned long) ino, block);
1364 Egdp:
1365         return ERR_PTR(-EIO);
1366 }
1367 
1368 void ext2_set_inode_flags(struct inode *inode)
1369 {
1370         unsigned int flags = EXT2_I(inode)->i_flags;
1371 
1372         inode->i_flags &= ~(S_SYNC | S_APPEND | S_IMMUTABLE | S_NOATIME |
1373                                 S_DIRSYNC | S_DAX);
1374         if (flags & EXT2_SYNC_FL)
1375                 inode->i_flags |= S_SYNC;
1376         if (flags & EXT2_APPEND_FL)
1377                 inode->i_flags |= S_APPEND;
1378         if (flags & EXT2_IMMUTABLE_FL)
1379                 inode->i_flags |= S_IMMUTABLE;
1380         if (flags & EXT2_NOATIME_FL)
1381                 inode->i_flags |= S_NOATIME;
1382         if (flags & EXT2_DIRSYNC_FL)
1383                 inode->i_flags |= S_DIRSYNC;
1384         if (test_opt(inode->i_sb, DAX) && S_ISREG(inode->i_mode))
1385                 inode->i_flags |= S_DAX;
1386 }
1387 
1388 void ext2_set_file_ops(struct inode *inode)
1389 {
1390         inode->i_op = &ext2_file_inode_operations;
1391         inode->i_fop = &ext2_file_operations;
1392         if (IS_DAX(inode))
1393                 inode->i_mapping->a_ops = &ext2_dax_aops;
1394         else if (test_opt(inode->i_sb, NOBH))
1395                 inode->i_mapping->a_ops = &ext2_nobh_aops;
1396         else
1397                 inode->i_mapping->a_ops = &ext2_aops;
1398 }
1399 
1400 struct inode *ext2_iget (struct super_block *sb, unsigned long ino)
1401 {
1402         struct ext2_inode_info *ei;
1403         struct buffer_head * bh = NULL;
1404         struct ext2_inode *raw_inode;
1405         struct inode *inode;
1406         long ret = -EIO;
1407         int n;
1408         uid_t i_uid;
1409         gid_t i_gid;
1410 
1411         inode = iget_locked(sb, ino);
1412         if (!inode)
1413                 return ERR_PTR(-ENOMEM);
1414         if (!(inode->i_state & I_NEW))
1415                 return inode;
1416 
1417         ei = EXT2_I(inode);
1418         ei->i_block_alloc_info = NULL;
1419 
1420         raw_inode = ext2_get_inode(inode->i_sb, ino, &bh);
1421         if (IS_ERR(raw_inode)) {
1422                 ret = PTR_ERR(raw_inode);
1423                 goto bad_inode;
1424         }
1425 
1426         inode->i_mode = le16_to_cpu(raw_inode->i_mode);
1427         i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
1428         i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
1429         if (!(test_opt (inode->i_sb, NO_UID32))) {
1430                 i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
1431                 i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
1432         }
1433         i_uid_write(inode, i_uid);
1434         i_gid_write(inode, i_gid);
1435         set_nlink(inode, le16_to_cpu(raw_inode->i_links_count));
1436         inode->i_size = le32_to_cpu(raw_inode->i_size);
1437         inode->i_atime.tv_sec = (signed)le32_to_cpu(raw_inode->i_atime);
1438         inode->i_ctime.tv_sec = (signed)le32_to_cpu(raw_inode->i_ctime);
1439         inode->i_mtime.tv_sec = (signed)le32_to_cpu(raw_inode->i_mtime);
1440         inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0;
1441         ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
1442         /* We now have enough fields to check if the inode was active or not.
1443          * This is needed because nfsd might try to access dead inodes
1444          * the test is that same one that e2fsck uses
1445          * NeilBrown 1999oct15
1446          */
1447         if (inode->i_nlink == 0 && (inode->i_mode == 0 || ei->i_dtime)) {
1448                 /* this inode is deleted */
1449                 ret = -ESTALE;
1450                 goto bad_inode;
1451         }
1452         inode->i_blocks = le32_to_cpu(raw_inode->i_blocks);
1453         ei->i_flags = le32_to_cpu(raw_inode->i_flags);
1454         ext2_set_inode_flags(inode);
1455         ei->i_faddr = le32_to_cpu(raw_inode->i_faddr);
1456         ei->i_frag_no = raw_inode->i_frag;
1457         ei->i_frag_size = raw_inode->i_fsize;
1458         ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl);
1459         ei->i_dir_acl = 0;
1460 
1461         if (ei->i_file_acl &&
1462             !ext2_data_block_valid(EXT2_SB(sb), ei->i_file_acl, 1)) {
1463                 ext2_error(sb, "ext2_iget", "bad extended attribute block %u",
1464                            ei->i_file_acl);
1465                 ret = -EFSCORRUPTED;
1466                 goto bad_inode;
1467         }
1468 
1469         if (S_ISREG(inode->i_mode))
1470                 inode->i_size |= ((__u64)le32_to_cpu(raw_inode->i_size_high)) << 32;
1471         else
1472                 ei->i_dir_acl = le32_to_cpu(raw_inode->i_dir_acl);
1473         if (i_size_read(inode) < 0) {
1474                 ret = -EFSCORRUPTED;
1475                 goto bad_inode;
1476         }
1477         ei->i_dtime = 0;
1478         inode->i_generation = le32_to_cpu(raw_inode->i_generation);
1479         ei->i_state = 0;
1480         ei->i_block_group = (ino - 1) / EXT2_INODES_PER_GROUP(inode->i_sb);
1481         ei->i_dir_start_lookup = 0;
1482 
1483         /*
1484          * NOTE! The in-memory inode i_data array is in little-endian order
1485          * even on big-endian machines: we do NOT byteswap the block numbers!
1486          */
1487         for (n = 0; n < EXT2_N_BLOCKS; n++)
1488                 ei->i_data[n] = raw_inode->i_block[n];
1489 
1490         if (S_ISREG(inode->i_mode)) {
1491                 ext2_set_file_ops(inode);
1492         } else if (S_ISDIR(inode->i_mode)) {
1493                 inode->i_op = &ext2_dir_inode_operations;
1494                 inode->i_fop = &ext2_dir_operations;
1495                 if (test_opt(inode->i_sb, NOBH))
1496                         inode->i_mapping->a_ops = &ext2_nobh_aops;
1497                 else
1498                         inode->i_mapping->a_ops = &ext2_aops;
1499         } else if (S_ISLNK(inode->i_mode)) {
1500                 if (ext2_inode_is_fast_symlink(inode)) {
1501                         inode->i_link = (char *)ei->i_data;
1502                         inode->i_op = &ext2_fast_symlink_inode_operations;
1503                         nd_terminate_link(ei->i_data, inode->i_size,
1504                                 sizeof(ei->i_data) - 1);
1505                 } else {
1506                         inode->i_op = &ext2_symlink_inode_operations;
1507                         inode_nohighmem(inode);
1508                         if (test_opt(inode->i_sb, NOBH))
1509                                 inode->i_mapping->a_ops = &ext2_nobh_aops;
1510                         else
1511                                 inode->i_mapping->a_ops = &ext2_aops;
1512                 }
1513         } else {
1514                 inode->i_op = &ext2_special_inode_operations;
1515                 if (raw_inode->i_block[0])
1516                         init_special_inode(inode, inode->i_mode,
1517                            old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
1518                 else 
1519                         init_special_inode(inode, inode->i_mode,
1520                            new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
1521         }
1522         brelse (bh);
1523         unlock_new_inode(inode);
1524         return inode;
1525         
1526 bad_inode:
1527         brelse(bh);
1528         iget_failed(inode);
1529         return ERR_PTR(ret);
1530 }
1531 
1532 static int __ext2_write_inode(struct inode *inode, int do_sync)
1533 {
1534         struct ext2_inode_info *ei = EXT2_I(inode);
1535         struct super_block *sb = inode->i_sb;
1536         ino_t ino = inode->i_ino;
1537         uid_t uid = i_uid_read(inode);
1538         gid_t gid = i_gid_read(inode);
1539         struct buffer_head * bh;
1540         struct ext2_inode * raw_inode = ext2_get_inode(sb, ino, &bh);
1541         int n;
1542         int err = 0;
1543 
1544         if (IS_ERR(raw_inode))
1545                 return -EIO;
1546 
1547         /* For fields not not tracking in the in-memory inode,
1548          * initialise them to zero for new inodes. */
1549         if (ei->i_state & EXT2_STATE_NEW)
1550                 memset(raw_inode, 0, EXT2_SB(sb)->s_inode_size);
1551 
1552         raw_inode->i_mode = cpu_to_le16(inode->i_mode);
1553         if (!(test_opt(sb, NO_UID32))) {
1554                 raw_inode->i_uid_low = cpu_to_le16(low_16_bits(uid));
1555                 raw_inode->i_gid_low = cpu_to_le16(low_16_bits(gid));
1556 /*
1557  * Fix up interoperability with old kernels. Otherwise, old inodes get
1558  * re-used with the upper 16 bits of the uid/gid intact
1559  */
1560                 if (!ei->i_dtime) {
1561                         raw_inode->i_uid_high = cpu_to_le16(high_16_bits(uid));
1562                         raw_inode->i_gid_high = cpu_to_le16(high_16_bits(gid));
1563                 } else {
1564                         raw_inode->i_uid_high = 0;
1565                         raw_inode->i_gid_high = 0;
1566                 }
1567         } else {
1568                 raw_inode->i_uid_low = cpu_to_le16(fs_high2lowuid(uid));
1569                 raw_inode->i_gid_low = cpu_to_le16(fs_high2lowgid(gid));
1570                 raw_inode->i_uid_high = 0;
1571                 raw_inode->i_gid_high = 0;
1572         }
1573         raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
1574         raw_inode->i_size = cpu_to_le32(inode->i_size);
1575         raw_inode->i_atime = cpu_to_le32(inode->i_atime.tv_sec);
1576         raw_inode->i_ctime = cpu_to_le32(inode->i_ctime.tv_sec);
1577         raw_inode->i_mtime = cpu_to_le32(inode->i_mtime.tv_sec);
1578 
1579         raw_inode->i_blocks = cpu_to_le32(inode->i_blocks);
1580         raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
1581         raw_inode->i_flags = cpu_to_le32(ei->i_flags);
1582         raw_inode->i_faddr = cpu_to_le32(ei->i_faddr);
1583         raw_inode->i_frag = ei->i_frag_no;
1584         raw_inode->i_fsize = ei->i_frag_size;
1585         raw_inode->i_file_acl = cpu_to_le32(ei->i_file_acl);
1586         if (!S_ISREG(inode->i_mode))
1587                 raw_inode->i_dir_acl = cpu_to_le32(ei->i_dir_acl);
1588         else {
1589                 raw_inode->i_size_high = cpu_to_le32(inode->i_size >> 32);
1590                 if (inode->i_size > 0x7fffffffULL) {
1591                         if (!EXT2_HAS_RO_COMPAT_FEATURE(sb,
1592                                         EXT2_FEATURE_RO_COMPAT_LARGE_FILE) ||
1593                             EXT2_SB(sb)->s_es->s_rev_level ==
1594                                         cpu_to_le32(EXT2_GOOD_OLD_REV)) {
1595                                /* If this is the first large file
1596                                 * created, add a flag to the superblock.
1597                                 */
1598                                 spin_lock(&EXT2_SB(sb)->s_lock);
1599                                 ext2_update_dynamic_rev(sb);
1600                                 EXT2_SET_RO_COMPAT_FEATURE(sb,
1601                                         EXT2_FEATURE_RO_COMPAT_LARGE_FILE);
1602                                 spin_unlock(&EXT2_SB(sb)->s_lock);
1603                                 ext2_sync_super(sb, EXT2_SB(sb)->s_es, 1);
1604                         }
1605                 }
1606         }
1607         
1608         raw_inode->i_generation = cpu_to_le32(inode->i_generation);
1609         if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
1610                 if (old_valid_dev(inode->i_rdev)) {
1611                         raw_inode->i_block[0] =
1612                                 cpu_to_le32(old_encode_dev(inode->i_rdev));
1613                         raw_inode->i_block[1] = 0;
1614                 } else {
1615                         raw_inode->i_block[0] = 0;
1616                         raw_inode->i_block[1] =
1617                                 cpu_to_le32(new_encode_dev(inode->i_rdev));
1618                         raw_inode->i_block[2] = 0;
1619                 }
1620         } else for (n = 0; n < EXT2_N_BLOCKS; n++)
1621                 raw_inode->i_block[n] = ei->i_data[n];
1622         mark_buffer_dirty(bh);
1623         if (do_sync) {
1624                 sync_dirty_buffer(bh);
1625                 if (buffer_req(bh) && !buffer_uptodate(bh)) {
1626                         printk ("IO error syncing ext2 inode [%s:%08lx]\n",
1627                                 sb->s_id, (unsigned long) ino);
1628                         err = -EIO;
1629                 }
1630         }
1631         ei->i_state &= ~EXT2_STATE_NEW;
1632         brelse (bh);
1633         return err;
1634 }
1635 
1636 int ext2_write_inode(struct inode *inode, struct writeback_control *wbc)
1637 {
1638         return __ext2_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
1639 }
1640 
1641 int ext2_getattr(struct user_namespace *mnt_userns, const struct path *path,
1642                  struct kstat *stat, u32 request_mask, unsigned int query_flags)
1643 {
1644         struct inode *inode = d_inode(path->dentry);
1645         struct ext2_inode_info *ei = EXT2_I(inode);
1646         unsigned int flags;
1647 
1648         flags = ei->i_flags & EXT2_FL_USER_VISIBLE;
1649         if (flags & EXT2_APPEND_FL)
1650                 stat->attributes |= STATX_ATTR_APPEND;
1651         if (flags & EXT2_COMPR_FL)
1652                 stat->attributes |= STATX_ATTR_COMPRESSED;
1653         if (flags & EXT2_IMMUTABLE_FL)
1654                 stat->attributes |= STATX_ATTR_IMMUTABLE;
1655         if (flags & EXT2_NODUMP_FL)
1656                 stat->attributes |= STATX_ATTR_NODUMP;
1657         stat->attributes_mask |= (STATX_ATTR_APPEND |
1658                         STATX_ATTR_COMPRESSED |
1659                         STATX_ATTR_ENCRYPTED |
1660                         STATX_ATTR_IMMUTABLE |
1661                         STATX_ATTR_NODUMP);
1662 
1663         generic_fillattr(&init_user_ns, inode, stat);
1664         return 0;
1665 }
1666 
1667 int ext2_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
1668                  struct iattr *iattr)
1669 {
1670         struct inode *inode = d_inode(dentry);
1671         int error;
1672 
1673         error = setattr_prepare(&init_user_ns, dentry, iattr);
1674         if (error)
1675                 return error;
1676 
1677         if (is_quota_modification(inode, iattr)) {
1678                 error = dquot_initialize(inode);
1679                 if (error)
1680                         return error;
1681         }
1682         if ((iattr->ia_valid & ATTR_UID && !uid_eq(iattr->ia_uid, inode->i_uid)) ||
1683             (iattr->ia_valid & ATTR_GID && !gid_eq(iattr->ia_gid, inode->i_gid))) {
1684                 error = dquot_transfer(inode, iattr);
1685                 if (error)
1686                         return error;
1687         }
1688         if (iattr->ia_valid & ATTR_SIZE && iattr->ia_size != inode->i_size) {
1689                 error = ext2_setsize(inode, iattr->ia_size);
1690                 if (error)
1691                         return error;
1692         }
1693         setattr_copy(&init_user_ns, inode, iattr);
1694         if (iattr->ia_valid & ATTR_MODE)
1695                 error = posix_acl_chmod(&init_user_ns, inode, inode->i_mode);
1696         mark_inode_dirty(inode);
1697 
1698         return error;
1699 }
1700 

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