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Linux/fs/ext2/inode.c

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  1 /*
  2  *  linux/fs/ext2/inode.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  *  from
 10  *
 11  *  linux/fs/minix/inode.c
 12  *
 13  *  Copyright (C) 1991, 1992  Linus Torvalds
 14  *
 15  *  Goal-directed block allocation by Stephen Tweedie
 16  *      (sct@dcs.ed.ac.uk), 1993, 1998
 17  *  Big-endian to little-endian byte-swapping/bitmaps by
 18  *        David S. Miller (davem@caip.rutgers.edu), 1995
 19  *  64-bit file support on 64-bit platforms by Jakub Jelinek
 20  *      (jj@sunsite.ms.mff.cuni.cz)
 21  *
 22  *  Assorted race fixes, rewrite of ext2_get_block() by Al Viro, 2000
 23  */
 24 
 25 #include <linux/time.h>
 26 #include <linux/highuid.h>
 27 #include <linux/pagemap.h>
 28 #include <linux/quotaops.h>
 29 #include <linux/writeback.h>
 30 #include <linux/buffer_head.h>
 31 #include <linux/mpage.h>
 32 #include <linux/fiemap.h>
 33 #include <linux/namei.h>
 34 #include <linux/aio.h>
 35 #include "ext2.h"
 36 #include "acl.h"
 37 #include "xip.h"
 38 #include "xattr.h"
 39 
 40 static int __ext2_write_inode(struct inode *inode, int do_sync);
 41 
 42 /*
 43  * Test whether an inode is a fast symlink.
 44  */
 45 static inline int ext2_inode_is_fast_symlink(struct inode *inode)
 46 {
 47         int ea_blocks = EXT2_I(inode)->i_file_acl ?
 48                 (inode->i_sb->s_blocksize >> 9) : 0;
 49 
 50         return (S_ISLNK(inode->i_mode) &&
 51                 inode->i_blocks - ea_blocks == 0);
 52 }
 53 
 54 static void ext2_truncate_blocks(struct inode *inode, loff_t offset);
 55 
 56 static void ext2_write_failed(struct address_space *mapping, loff_t to)
 57 {
 58         struct inode *inode = mapping->host;
 59 
 60         if (to > inode->i_size) {
 61                 truncate_pagecache(inode, inode->i_size);
 62                 ext2_truncate_blocks(inode, inode->i_size);
 63         }
 64 }
 65 
 66 /*
 67  * Called at the last iput() if i_nlink is zero.
 68  */
 69 void ext2_evict_inode(struct inode * inode)
 70 {
 71         struct ext2_block_alloc_info *rsv;
 72         int want_delete = 0;
 73 
 74         if (!inode->i_nlink && !is_bad_inode(inode)) {
 75                 want_delete = 1;
 76                 dquot_initialize(inode);
 77         } else {
 78                 dquot_drop(inode);
 79         }
 80 
 81         truncate_inode_pages(&inode->i_data, 0);
 82 
 83         if (want_delete) {
 84                 sb_start_intwrite(inode->i_sb);
 85                 /* set dtime */
 86                 EXT2_I(inode)->i_dtime  = get_seconds();
 87                 mark_inode_dirty(inode);
 88                 __ext2_write_inode(inode, inode_needs_sync(inode));
 89                 /* truncate to 0 */
 90                 inode->i_size = 0;
 91                 if (inode->i_blocks)
 92                         ext2_truncate_blocks(inode, 0);
 93                 ext2_xattr_delete_inode(inode);
 94         }
 95 
 96         invalidate_inode_buffers(inode);
 97         clear_inode(inode);
 98 
 99         ext2_discard_reservation(inode);
100         rsv = EXT2_I(inode)->i_block_alloc_info;
101         EXT2_I(inode)->i_block_alloc_info = NULL;
102         if (unlikely(rsv))
103                 kfree(rsv);
104 
105         if (want_delete) {
106                 ext2_free_inode(inode);
107                 sb_end_intwrite(inode->i_sb);
108         }
109 }
110 
111 typedef struct {
112         __le32  *p;
113         __le32  key;
114         struct buffer_head *bh;
115 } Indirect;
116 
117 static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
118 {
119         p->key = *(p->p = v);
120         p->bh = bh;
121 }
122 
123 static inline int verify_chain(Indirect *from, Indirect *to)
124 {
125         while (from <= to && from->key == *from->p)
126                 from++;
127         return (from > to);
128 }
129 
130 /**
131  *      ext2_block_to_path - parse the block number into array of offsets
132  *      @inode: inode in question (we are only interested in its superblock)
133  *      @i_block: block number to be parsed
134  *      @offsets: array to store the offsets in
135  *      @boundary: set this non-zero if the referred-to block is likely to be
136  *             followed (on disk) by an indirect block.
137  *      To store the locations of file's data ext2 uses a data structure common
138  *      for UNIX filesystems - tree of pointers anchored in the inode, with
139  *      data blocks at leaves and indirect blocks in intermediate nodes.
140  *      This function translates the block number into path in that tree -
141  *      return value is the path length and @offsets[n] is the offset of
142  *      pointer to (n+1)th node in the nth one. If @block is out of range
143  *      (negative or too large) warning is printed and zero returned.
144  *
145  *      Note: function doesn't find node addresses, so no IO is needed. All
146  *      we need to know is the capacity of indirect blocks (taken from the
147  *      inode->i_sb).
148  */
149 
150 /*
151  * Portability note: the last comparison (check that we fit into triple
152  * indirect block) is spelled differently, because otherwise on an
153  * architecture with 32-bit longs and 8Kb pages we might get into trouble
154  * if our filesystem had 8Kb blocks. We might use long long, but that would
155  * kill us on x86. Oh, well, at least the sign propagation does not matter -
156  * i_block would have to be negative in the very beginning, so we would not
157  * get there at all.
158  */
159 
160 static int ext2_block_to_path(struct inode *inode,
161                         long i_block, int offsets[4], int *boundary)
162 {
163         int ptrs = EXT2_ADDR_PER_BLOCK(inode->i_sb);
164         int ptrs_bits = EXT2_ADDR_PER_BLOCK_BITS(inode->i_sb);
165         const long direct_blocks = EXT2_NDIR_BLOCKS,
166                 indirect_blocks = ptrs,
167                 double_blocks = (1 << (ptrs_bits * 2));
168         int n = 0;
169         int final = 0;
170 
171         if (i_block < 0) {
172                 ext2_msg(inode->i_sb, KERN_WARNING,
173                         "warning: %s: block < 0", __func__);
174         } else if (i_block < direct_blocks) {
175                 offsets[n++] = i_block;
176                 final = direct_blocks;
177         } else if ( (i_block -= direct_blocks) < indirect_blocks) {
178                 offsets[n++] = EXT2_IND_BLOCK;
179                 offsets[n++] = i_block;
180                 final = ptrs;
181         } else if ((i_block -= indirect_blocks) < double_blocks) {
182                 offsets[n++] = EXT2_DIND_BLOCK;
183                 offsets[n++] = i_block >> ptrs_bits;
184                 offsets[n++] = i_block & (ptrs - 1);
185                 final = ptrs;
186         } else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
187                 offsets[n++] = EXT2_TIND_BLOCK;
188                 offsets[n++] = i_block >> (ptrs_bits * 2);
189                 offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
190                 offsets[n++] = i_block & (ptrs - 1);
191                 final = ptrs;
192         } else {
193                 ext2_msg(inode->i_sb, KERN_WARNING,
194                         "warning: %s: block is too big", __func__);
195         }
196         if (boundary)
197                 *boundary = final - 1 - (i_block & (ptrs - 1));
198 
199         return n;
200 }
201 
202 /**
203  *      ext2_get_branch - read the chain of indirect blocks leading to data
204  *      @inode: inode in question
205  *      @depth: depth of the chain (1 - direct pointer, etc.)
206  *      @offsets: offsets of pointers in inode/indirect blocks
207  *      @chain: place to store the result
208  *      @err: here we store the error value
209  *
210  *      Function fills the array of triples <key, p, bh> and returns %NULL
211  *      if everything went OK or the pointer to the last filled triple
212  *      (incomplete one) otherwise. Upon the return chain[i].key contains
213  *      the number of (i+1)-th block in the chain (as it is stored in memory,
214  *      i.e. little-endian 32-bit), chain[i].p contains the address of that
215  *      number (it points into struct inode for i==0 and into the bh->b_data
216  *      for i>0) and chain[i].bh points to the buffer_head of i-th indirect
217  *      block for i>0 and NULL for i==0. In other words, it holds the block
218  *      numbers of the chain, addresses they were taken from (and where we can
219  *      verify that chain did not change) and buffer_heads hosting these
220  *      numbers.
221  *
222  *      Function stops when it stumbles upon zero pointer (absent block)
223  *              (pointer to last triple returned, *@err == 0)
224  *      or when it gets an IO error reading an indirect block
225  *              (ditto, *@err == -EIO)
226  *      or when it notices that chain had been changed while it was reading
227  *              (ditto, *@err == -EAGAIN)
228  *      or when it reads all @depth-1 indirect blocks successfully and finds
229  *      the whole chain, all way to the data (returns %NULL, *err == 0).
230  */
231 static Indirect *ext2_get_branch(struct inode *inode,
232                                  int depth,
233                                  int *offsets,
234                                  Indirect chain[4],
235                                  int *err)
236 {
237         struct super_block *sb = inode->i_sb;
238         Indirect *p = chain;
239         struct buffer_head *bh;
240 
241         *err = 0;
242         /* i_data is not going away, no lock needed */
243         add_chain (chain, NULL, EXT2_I(inode)->i_data + *offsets);
244         if (!p->key)
245                 goto no_block;
246         while (--depth) {
247                 bh = sb_bread(sb, le32_to_cpu(p->key));
248                 if (!bh)
249                         goto failure;
250                 read_lock(&EXT2_I(inode)->i_meta_lock);
251                 if (!verify_chain(chain, p))
252                         goto changed;
253                 add_chain(++p, bh, (__le32*)bh->b_data + *++offsets);
254                 read_unlock(&EXT2_I(inode)->i_meta_lock);
255                 if (!p->key)
256                         goto no_block;
257         }
258         return NULL;
259 
260 changed:
261         read_unlock(&EXT2_I(inode)->i_meta_lock);
262         brelse(bh);
263         *err = -EAGAIN;
264         goto no_block;
265 failure:
266         *err = -EIO;
267 no_block:
268         return p;
269 }
270 
271 /**
272  *      ext2_find_near - find a place for allocation with sufficient locality
273  *      @inode: owner
274  *      @ind: descriptor of indirect block.
275  *
276  *      This function returns the preferred place for block allocation.
277  *      It is used when heuristic for sequential allocation fails.
278  *      Rules are:
279  *        + if there is a block to the left of our position - allocate near it.
280  *        + if pointer will live in indirect block - allocate near that block.
281  *        + if pointer will live in inode - allocate in the same cylinder group.
282  *
283  * In the latter case we colour the starting block by the callers PID to
284  * prevent it from clashing with concurrent allocations for a different inode
285  * in the same block group.   The PID is used here so that functionally related
286  * files will be close-by on-disk.
287  *
288  *      Caller must make sure that @ind is valid and will stay that way.
289  */
290 
291 static ext2_fsblk_t ext2_find_near(struct inode *inode, Indirect *ind)
292 {
293         struct ext2_inode_info *ei = EXT2_I(inode);
294         __le32 *start = ind->bh ? (__le32 *) ind->bh->b_data : ei->i_data;
295         __le32 *p;
296         ext2_fsblk_t bg_start;
297         ext2_fsblk_t colour;
298 
299         /* Try to find previous block */
300         for (p = ind->p - 1; p >= start; p--)
301                 if (*p)
302                         return le32_to_cpu(*p);
303 
304         /* No such thing, so let's try location of indirect block */
305         if (ind->bh)
306                 return ind->bh->b_blocknr;
307 
308         /*
309          * It is going to be referred from inode itself? OK, just put it into
310          * the same cylinder group then.
311          */
312         bg_start = ext2_group_first_block_no(inode->i_sb, ei->i_block_group);
313         colour = (current->pid % 16) *
314                         (EXT2_BLOCKS_PER_GROUP(inode->i_sb) / 16);
315         return bg_start + colour;
316 }
317 
318 /**
319  *      ext2_find_goal - find a preferred place for allocation.
320  *      @inode: owner
321  *      @block:  block we want
322  *      @partial: pointer to the last triple within a chain
323  *
324  *      Returns preferred place for a block (the goal).
325  */
326 
327 static inline ext2_fsblk_t ext2_find_goal(struct inode *inode, long block,
328                                           Indirect *partial)
329 {
330         struct ext2_block_alloc_info *block_i;
331 
332         block_i = EXT2_I(inode)->i_block_alloc_info;
333 
334         /*
335          * try the heuristic for sequential allocation,
336          * failing that at least try to get decent locality.
337          */
338         if (block_i && (block == block_i->last_alloc_logical_block + 1)
339                 && (block_i->last_alloc_physical_block != 0)) {
340                 return block_i->last_alloc_physical_block + 1;
341         }
342 
343         return ext2_find_near(inode, partial);
344 }
345 
346 /**
347  *      ext2_blks_to_allocate: Look up the block map and count the number
348  *      of direct blocks need to be allocated for the given branch.
349  *
350  *      @branch: chain of indirect blocks
351  *      @k: number of blocks need for indirect blocks
352  *      @blks: number of data blocks to be mapped.
353  *      @blocks_to_boundary:  the offset in the indirect block
354  *
355  *      return the total number of blocks to be allocate, including the
356  *      direct and indirect blocks.
357  */
358 static int
359 ext2_blks_to_allocate(Indirect * branch, int k, unsigned long blks,
360                 int blocks_to_boundary)
361 {
362         unsigned long count = 0;
363 
364         /*
365          * Simple case, [t,d]Indirect block(s) has not allocated yet
366          * then it's clear blocks on that path have not allocated
367          */
368         if (k > 0) {
369                 /* right now don't hanel cross boundary allocation */
370                 if (blks < blocks_to_boundary + 1)
371                         count += blks;
372                 else
373                         count += blocks_to_boundary + 1;
374                 return count;
375         }
376 
377         count++;
378         while (count < blks && count <= blocks_to_boundary
379                 && le32_to_cpu(*(branch[0].p + count)) == 0) {
380                 count++;
381         }
382         return count;
383 }
384 
385 /**
386  *      ext2_alloc_blocks: multiple allocate blocks needed for a branch
387  *      @indirect_blks: the number of blocks need to allocate for indirect
388  *                      blocks
389  *
390  *      @new_blocks: on return it will store the new block numbers for
391  *      the indirect blocks(if needed) and the first direct block,
392  *      @blks:  on return it will store the total number of allocated
393  *              direct blocks
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  *      @num: depth of the chain (number of blocks to allocate)
452  *      @offsets: offsets (in the blocks) to store the pointers to next.
453  *      @branch: place to store the chain in.
454  *
455  *      This function allocates @num blocks, zeroes out all but the last one,
456  *      links them into chain and (if we are synchronous) writes them to disk.
457  *      In other words, it prepares a branch that can be spliced onto the
458  *      inode. It stores the information about that chain in the branch[], in
459  *      the same format as ext2_get_branch() would do. We are calling it after
460  *      we had read the existing part of chain and partial points to the last
461  *      triple of that (one with zero ->key). Upon the exit we have the same
462  *      picture as after the successful ext2_get_block(), except that in one
463  *      place chain is disconnected - *branch->p is still zero (we did not
464  *      set the last link), but branch->key contains the number that should
465  *      be placed into *branch->p to fill that gap.
466  *
467  *      If allocation fails we free all blocks we've allocated (and forget
468  *      their buffer_heads) and return the error value the from failed
469  *      ext2_alloc_block() (normally -ENOSPC). Otherwise we set the chain
470  *      as described above and return 0.
471  */
472 
473 static int ext2_alloc_branch(struct inode *inode,
474                         int indirect_blks, int *blks, ext2_fsblk_t goal,
475                         int *offsets, Indirect *branch)
476 {
477         int blocksize = inode->i_sb->s_blocksize;
478         int i, n = 0;
479         int err = 0;
480         struct buffer_head *bh;
481         int num;
482         ext2_fsblk_t new_blocks[4];
483         ext2_fsblk_t current_block;
484 
485         num = ext2_alloc_blocks(inode, goal, indirect_blks,
486                                 *blks, new_blocks, &err);
487         if (err)
488                 return err;
489 
490         branch[0].key = cpu_to_le32(new_blocks[0]);
491         /*
492          * metadata blocks and data blocks are allocated.
493          */
494         for (n = 1; n <= indirect_blks;  n++) {
495                 /*
496                  * Get buffer_head for parent block, zero it out
497                  * and set the pointer to new one, then send
498                  * parent to disk.
499                  */
500                 bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
501                 if (unlikely(!bh)) {
502                         err = -ENOMEM;
503                         goto failed;
504                 }
505                 branch[n].bh = bh;
506                 lock_buffer(bh);
507                 memset(bh->b_data, 0, blocksize);
508                 branch[n].p = (__le32 *) bh->b_data + offsets[n];
509                 branch[n].key = cpu_to_le32(new_blocks[n]);
510                 *branch[n].p = branch[n].key;
511                 if ( n == indirect_blks) {
512                         current_block = new_blocks[n];
513                         /*
514                          * End of chain, update the last new metablock of
515                          * the chain to point to the new allocated
516                          * data blocks numbers
517                          */
518                         for (i=1; i < num; i++)
519                                 *(branch[n].p + i) = cpu_to_le32(++current_block);
520                 }
521                 set_buffer_uptodate(bh);
522                 unlock_buffer(bh);
523                 mark_buffer_dirty_inode(bh, inode);
524                 /* We used to sync bh here if IS_SYNC(inode).
525                  * But we now rely upon generic_write_sync()
526                  * and b_inode_buffers.  But not for directories.
527                  */
528                 if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
529                         sync_dirty_buffer(bh);
530         }
531         *blks = num;
532         return err;
533 
534 failed:
535         for (i = 1; i < n; i++)
536                 bforget(branch[i].bh);
537         for (i = 0; i < indirect_blks; i++)
538                 ext2_free_blocks(inode, new_blocks[i], 1);
539         ext2_free_blocks(inode, new_blocks[i], num);
540         return err;
541 }
542 
543 /**
544  * ext2_splice_branch - splice the allocated branch onto inode.
545  * @inode: owner
546  * @block: (logical) number of block we are adding
547  * @where: location of missing link
548  * @num:   number of indirect blocks we are adding
549  * @blks:  number of direct blocks we are adding
550  *
551  * This function fills the missing link and does all housekeeping needed in
552  * inode (->i_blocks, etc.). In case of success we end up with the full
553  * chain to new block and return 0.
554  */
555 static void ext2_splice_branch(struct inode *inode,
556                         long block, Indirect *where, int num, int blks)
557 {
558         int i;
559         struct ext2_block_alloc_info *block_i;
560         ext2_fsblk_t current_block;
561 
562         block_i = EXT2_I(inode)->i_block_alloc_info;
563 
564         /* XXX LOCKING probably should have i_meta_lock ?*/
565         /* That's it */
566 
567         *where->p = where->key;
568 
569         /*
570          * Update the host buffer_head or inode to point to more just allocated
571          * direct blocks blocks
572          */
573         if (num == 0 && blks > 1) {
574                 current_block = le32_to_cpu(where->key) + 1;
575                 for (i = 1; i < blks; i++)
576                         *(where->p + i ) = cpu_to_le32(current_block++);
577         }
578 
579         /*
580          * update the most recently allocated logical & physical block
581          * in i_block_alloc_info, to assist find the proper goal block for next
582          * allocation
583          */
584         if (block_i) {
585                 block_i->last_alloc_logical_block = block + blks - 1;
586                 block_i->last_alloc_physical_block =
587                                 le32_to_cpu(where[num].key) + blks - 1;
588         }
589 
590         /* We are done with atomic stuff, now do the rest of housekeeping */
591 
592         /* had we spliced it onto indirect block? */
593         if (where->bh)
594                 mark_buffer_dirty_inode(where->bh, inode);
595 
596         inode->i_ctime = CURRENT_TIME_SEC;
597         mark_inode_dirty(inode);
598 }
599 
600 /*
601  * Allocation strategy is simple: if we have to allocate something, we will
602  * have to go the whole way to leaf. So let's do it before attaching anything
603  * to tree, set linkage between the newborn blocks, write them if sync is
604  * required, recheck the path, free and repeat if check fails, otherwise
605  * set the last missing link (that will protect us from any truncate-generated
606  * removals - all blocks on the path are immune now) and possibly force the
607  * write on the parent block.
608  * That has a nice additional property: no special recovery from the failed
609  * allocations is needed - we simply release blocks and do not touch anything
610  * reachable from inode.
611  *
612  * `handle' can be NULL if create == 0.
613  *
614  * return > 0, # of blocks mapped or allocated.
615  * return = 0, if plain lookup failed.
616  * return < 0, error case.
617  */
618 static int ext2_get_blocks(struct inode *inode,
619                            sector_t iblock, unsigned long maxblocks,
620                            struct buffer_head *bh_result,
621                            int create)
622 {
623         int err = -EIO;
624         int offsets[4];
625         Indirect chain[4];
626         Indirect *partial;
627         ext2_fsblk_t goal;
628         int indirect_blks;
629         int blocks_to_boundary = 0;
630         int depth;
631         struct ext2_inode_info *ei = EXT2_I(inode);
632         int count = 0;
633         ext2_fsblk_t first_block = 0;
634 
635         BUG_ON(maxblocks == 0);
636 
637         depth = ext2_block_to_path(inode,iblock,offsets,&blocks_to_boundary);
638 
639         if (depth == 0)
640                 return (err);
641 
642         partial = ext2_get_branch(inode, depth, offsets, chain, &err);
643         /* Simplest case - block found, no allocation needed */
644         if (!partial) {
645                 first_block = le32_to_cpu(chain[depth - 1].key);
646                 clear_buffer_new(bh_result); /* What's this do? */
647                 count++;
648                 /*map more blocks*/
649                 while (count < maxblocks && count <= blocks_to_boundary) {
650                         ext2_fsblk_t blk;
651 
652                         if (!verify_chain(chain, chain + depth - 1)) {
653                                 /*
654                                  * Indirect block might be removed by
655                                  * truncate while we were reading it.
656                                  * Handling of that case: forget what we've
657                                  * got now, go to reread.
658                                  */
659                                 err = -EAGAIN;
660                                 count = 0;
661                                 break;
662                         }
663                         blk = le32_to_cpu(*(chain[depth-1].p + count));
664                         if (blk == first_block + count)
665                                 count++;
666                         else
667                                 break;
668                 }
669                 if (err != -EAGAIN)
670                         goto got_it;
671         }
672 
673         /* Next simple case - plain lookup or failed read of indirect block */
674         if (!create || err == -EIO)
675                 goto cleanup;
676 
677         mutex_lock(&ei->truncate_mutex);
678         /*
679          * If the indirect block is missing while we are reading
680          * the chain(ext2_get_branch() returns -EAGAIN err), or
681          * if the chain has been changed after we grab the semaphore,
682          * (either because another process truncated this branch, or
683          * another get_block allocated this branch) re-grab the chain to see if
684          * the request block has been allocated or not.
685          *
686          * Since we already block the truncate/other get_block
687          * at this point, we will have the current copy of the chain when we
688          * splice the branch into the tree.
689          */
690         if (err == -EAGAIN || !verify_chain(chain, partial)) {
691                 while (partial > chain) {
692                         brelse(partial->bh);
693                         partial--;
694                 }
695                 partial = ext2_get_branch(inode, depth, offsets, chain, &err);
696                 if (!partial) {
697                         count++;
698                         mutex_unlock(&ei->truncate_mutex);
699                         if (err)
700                                 goto cleanup;
701                         clear_buffer_new(bh_result);
702                         goto got_it;
703                 }
704         }
705 
706         /*
707          * Okay, we need to do block allocation.  Lazily initialize the block
708          * allocation info here if necessary
709         */
710         if (S_ISREG(inode->i_mode) && (!ei->i_block_alloc_info))
711                 ext2_init_block_alloc_info(inode);
712 
713         goal = ext2_find_goal(inode, iblock, partial);
714 
715         /* the number of blocks need to allocate for [d,t]indirect blocks */
716         indirect_blks = (chain + depth) - partial - 1;
717         /*
718          * Next look up the indirect map to count the totoal number of
719          * direct blocks to allocate for this branch.
720          */
721         count = ext2_blks_to_allocate(partial, indirect_blks,
722                                         maxblocks, blocks_to_boundary);
723         /*
724          * XXX ???? Block out ext2_truncate while we alter the tree
725          */
726         err = ext2_alloc_branch(inode, indirect_blks, &count, goal,
727                                 offsets + (partial - chain), partial);
728 
729         if (err) {
730                 mutex_unlock(&ei->truncate_mutex);
731                 goto cleanup;
732         }
733 
734         if (ext2_use_xip(inode->i_sb)) {
735                 /*
736                  * we need to clear the block
737                  */
738                 err = ext2_clear_xip_target (inode,
739                         le32_to_cpu(chain[depth-1].key));
740                 if (err) {
741                         mutex_unlock(&ei->truncate_mutex);
742                         goto cleanup;
743                 }
744         }
745 
746         ext2_splice_branch(inode, iblock, partial, indirect_blks, count);
747         mutex_unlock(&ei->truncate_mutex);
748         set_buffer_new(bh_result);
749 got_it:
750         map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key));
751         if (count > blocks_to_boundary)
752                 set_buffer_boundary(bh_result);
753         err = count;
754         /* Clean up and exit */
755         partial = chain + depth - 1;    /* the whole chain */
756 cleanup:
757         while (partial > chain) {
758                 brelse(partial->bh);
759                 partial--;
760         }
761         return err;
762 }
763 
764 int ext2_get_block(struct inode *inode, sector_t iblock, struct buffer_head *bh_result, int create)
765 {
766         unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
767         int ret = ext2_get_blocks(inode, iblock, max_blocks,
768                               bh_result, create);
769         if (ret > 0) {
770                 bh_result->b_size = (ret << inode->i_blkbits);
771                 ret = 0;
772         }
773         return ret;
774 
775 }
776 
777 int ext2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
778                 u64 start, u64 len)
779 {
780         return generic_block_fiemap(inode, fieinfo, start, len,
781                                     ext2_get_block);
782 }
783 
784 static int ext2_writepage(struct page *page, struct writeback_control *wbc)
785 {
786         return block_write_full_page(page, ext2_get_block, wbc);
787 }
788 
789 static int ext2_readpage(struct file *file, struct page *page)
790 {
791         return mpage_readpage(page, ext2_get_block);
792 }
793 
794 static int
795 ext2_readpages(struct file *file, struct address_space *mapping,
796                 struct list_head *pages, unsigned nr_pages)
797 {
798         return mpage_readpages(mapping, pages, nr_pages, ext2_get_block);
799 }
800 
801 static int
802 ext2_write_begin(struct file *file, struct address_space *mapping,
803                 loff_t pos, unsigned len, unsigned flags,
804                 struct page **pagep, void **fsdata)
805 {
806         int ret;
807 
808         ret = block_write_begin(mapping, pos, len, flags, pagep,
809                                 ext2_get_block);
810         if (ret < 0)
811                 ext2_write_failed(mapping, pos + len);
812         return ret;
813 }
814 
815 static int ext2_write_end(struct file *file, struct address_space *mapping,
816                         loff_t pos, unsigned len, unsigned copied,
817                         struct page *page, void *fsdata)
818 {
819         int ret;
820 
821         ret = generic_write_end(file, mapping, pos, len, copied, page, fsdata);
822         if (ret < len)
823                 ext2_write_failed(mapping, pos + len);
824         return ret;
825 }
826 
827 static int
828 ext2_nobh_write_begin(struct file *file, struct address_space *mapping,
829                 loff_t pos, unsigned len, unsigned flags,
830                 struct page **pagep, void **fsdata)
831 {
832         int ret;
833 
834         ret = nobh_write_begin(mapping, pos, len, flags, pagep, fsdata,
835                                ext2_get_block);
836         if (ret < 0)
837                 ext2_write_failed(mapping, pos + len);
838         return ret;
839 }
840 
841 static int ext2_nobh_writepage(struct page *page,
842                         struct writeback_control *wbc)
843 {
844         return nobh_writepage(page, ext2_get_block, wbc);
845 }
846 
847 static sector_t ext2_bmap(struct address_space *mapping, sector_t block)
848 {
849         return generic_block_bmap(mapping,block,ext2_get_block);
850 }
851 
852 static ssize_t
853 ext2_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
854                         loff_t offset, unsigned long nr_segs)
855 {
856         struct file *file = iocb->ki_filp;
857         struct address_space *mapping = file->f_mapping;
858         struct inode *inode = mapping->host;
859         ssize_t ret;
860 
861         ret = blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs,
862                                  ext2_get_block);
863         if (ret < 0 && (rw & WRITE))
864                 ext2_write_failed(mapping, offset + iov_length(iov, nr_segs));
865         return ret;
866 }
867 
868 static int
869 ext2_writepages(struct address_space *mapping, struct writeback_control *wbc)
870 {
871         return mpage_writepages(mapping, wbc, ext2_get_block);
872 }
873 
874 const struct address_space_operations ext2_aops = {
875         .readpage               = ext2_readpage,
876         .readpages              = ext2_readpages,
877         .writepage              = ext2_writepage,
878         .write_begin            = ext2_write_begin,
879         .write_end              = ext2_write_end,
880         .bmap                   = ext2_bmap,
881         .direct_IO              = ext2_direct_IO,
882         .writepages             = ext2_writepages,
883         .migratepage            = buffer_migrate_page,
884         .is_partially_uptodate  = block_is_partially_uptodate,
885         .error_remove_page      = generic_error_remove_page,
886 };
887 
888 const struct address_space_operations ext2_aops_xip = {
889         .bmap                   = ext2_bmap,
890         .get_xip_mem            = ext2_get_xip_mem,
891 };
892 
893 const struct address_space_operations ext2_nobh_aops = {
894         .readpage               = ext2_readpage,
895         .readpages              = ext2_readpages,
896         .writepage              = ext2_nobh_writepage,
897         .write_begin            = ext2_nobh_write_begin,
898         .write_end              = nobh_write_end,
899         .bmap                   = ext2_bmap,
900         .direct_IO              = ext2_direct_IO,
901         .writepages             = ext2_writepages,
902         .migratepage            = buffer_migrate_page,
903         .error_remove_page      = generic_error_remove_page,
904 };
905 
906 /*
907  * Probably it should be a library function... search for first non-zero word
908  * or memcmp with zero_page, whatever is better for particular architecture.
909  * Linus?
910  */
911 static inline int all_zeroes(__le32 *p, __le32 *q)
912 {
913         while (p < q)
914                 if (*p++)
915                         return 0;
916         return 1;
917 }
918 
919 /**
920  *      ext2_find_shared - find the indirect blocks for partial truncation.
921  *      @inode:   inode in question
922  *      @depth:   depth of the affected branch
923  *      @offsets: offsets of pointers in that branch (see ext2_block_to_path)
924  *      @chain:   place to store the pointers to partial indirect blocks
925  *      @top:     place to the (detached) top of branch
926  *
927  *      This is a helper function used by ext2_truncate().
928  *
929  *      When we do truncate() we may have to clean the ends of several indirect
930  *      blocks but leave the blocks themselves alive. Block is partially
931  *      truncated if some data below the new i_size is referred from it (and
932  *      it is on the path to the first completely truncated data block, indeed).
933  *      We have to free the top of that path along with everything to the right
934  *      of the path. Since no allocation past the truncation point is possible
935  *      until ext2_truncate() finishes, we may safely do the latter, but top
936  *      of branch may require special attention - pageout below the truncation
937  *      point might try to populate it.
938  *
939  *      We atomically detach the top of branch from the tree, store the block
940  *      number of its root in *@top, pointers to buffer_heads of partially
941  *      truncated blocks - in @chain[].bh and pointers to their last elements
942  *      that should not be removed - in @chain[].p. Return value is the pointer
943  *      to last filled element of @chain.
944  *
945  *      The work left to caller to do the actual freeing of subtrees:
946  *              a) free the subtree starting from *@top
947  *              b) free the subtrees whose roots are stored in
948  *                      (@chain[i].p+1 .. end of @chain[i].bh->b_data)
949  *              c) free the subtrees growing from the inode past the @chain[0].p
950  *                      (no partially truncated stuff there).
951  */
952 
953 static Indirect *ext2_find_shared(struct inode *inode,
954                                 int depth,
955                                 int offsets[4],
956                                 Indirect chain[4],
957                                 __le32 *top)
958 {
959         Indirect *partial, *p;
960         int k, err;
961 
962         *top = 0;
963         for (k = depth; k > 1 && !offsets[k-1]; k--)
964                 ;
965         partial = ext2_get_branch(inode, k, offsets, chain, &err);
966         if (!partial)
967                 partial = chain + k-1;
968         /*
969          * If the branch acquired continuation since we've looked at it -
970          * fine, it should all survive and (new) top doesn't belong to us.
971          */
972         write_lock(&EXT2_I(inode)->i_meta_lock);
973         if (!partial->key && *partial->p) {
974                 write_unlock(&EXT2_I(inode)->i_meta_lock);
975                 goto no_top;
976         }
977         for (p=partial; p>chain && all_zeroes((__le32*)p->bh->b_data,p->p); p--)
978                 ;
979         /*
980          * OK, we've found the last block that must survive. The rest of our
981          * branch should be detached before unlocking. However, if that rest
982          * of branch is all ours and does not grow immediately from the inode
983          * it's easier to cheat and just decrement partial->p.
984          */
985         if (p == chain + k - 1 && p > chain) {
986                 p->p--;
987         } else {
988                 *top = *p->p;
989                 *p->p = 0;
990         }
991         write_unlock(&EXT2_I(inode)->i_meta_lock);
992 
993         while(partial > p)
994         {
995                 brelse(partial->bh);
996                 partial--;
997         }
998 no_top:
999         return partial;
1000 }
1001 
1002 /**
1003  *      ext2_free_data - free a list of data blocks
1004  *      @inode: inode we are dealing with
1005  *      @p:     array of block numbers
1006  *      @q:     points immediately past the end of array
1007  *
1008  *      We are freeing all blocks referred from that array (numbers are
1009  *      stored as little-endian 32-bit) and updating @inode->i_blocks
1010  *      appropriately.
1011  */
1012 static inline void ext2_free_data(struct inode *inode, __le32 *p, __le32 *q)
1013 {
1014         unsigned long block_to_free = 0, count = 0;
1015         unsigned long nr;
1016 
1017         for ( ; p < q ; p++) {
1018                 nr = le32_to_cpu(*p);
1019                 if (nr) {
1020                         *p = 0;
1021                         /* accumulate blocks to free if they're contiguous */
1022                         if (count == 0)
1023                                 goto free_this;
1024                         else if (block_to_free == nr - count)
1025                                 count++;
1026                         else {
1027                                 ext2_free_blocks (inode, block_to_free, count);
1028                                 mark_inode_dirty(inode);
1029                         free_this:
1030                                 block_to_free = nr;
1031                                 count = 1;
1032                         }
1033                 }
1034         }
1035         if (count > 0) {
1036                 ext2_free_blocks (inode, block_to_free, count);
1037                 mark_inode_dirty(inode);
1038         }
1039 }
1040 
1041 /**
1042  *      ext2_free_branches - free an array of branches
1043  *      @inode: inode we are dealing with
1044  *      @p:     array of block numbers
1045  *      @q:     pointer immediately past the end of array
1046  *      @depth: depth of the branches to free
1047  *
1048  *      We are freeing all blocks referred from these branches (numbers are
1049  *      stored as little-endian 32-bit) and updating @inode->i_blocks
1050  *      appropriately.
1051  */
1052 static void ext2_free_branches(struct inode *inode, __le32 *p, __le32 *q, int depth)
1053 {
1054         struct buffer_head * bh;
1055         unsigned long nr;
1056 
1057         if (depth--) {
1058                 int addr_per_block = EXT2_ADDR_PER_BLOCK(inode->i_sb);
1059                 for ( ; p < q ; p++) {
1060                         nr = le32_to_cpu(*p);
1061                         if (!nr)
1062                                 continue;
1063                         *p = 0;
1064                         bh = sb_bread(inode->i_sb, nr);
1065                         /*
1066                          * A read failure? Report error and clear slot
1067                          * (should be rare).
1068                          */ 
1069                         if (!bh) {
1070                                 ext2_error(inode->i_sb, "ext2_free_branches",
1071                                         "Read failure, inode=%ld, block=%ld",
1072                                         inode->i_ino, nr);
1073                                 continue;
1074                         }
1075                         ext2_free_branches(inode,
1076                                            (__le32*)bh->b_data,
1077                                            (__le32*)bh->b_data + addr_per_block,
1078                                            depth);
1079                         bforget(bh);
1080                         ext2_free_blocks(inode, nr, 1);
1081                         mark_inode_dirty(inode);
1082                 }
1083         } else
1084                 ext2_free_data(inode, p, q);
1085 }
1086 
1087 static void __ext2_truncate_blocks(struct inode *inode, loff_t offset)
1088 {
1089         __le32 *i_data = EXT2_I(inode)->i_data;
1090         struct ext2_inode_info *ei = EXT2_I(inode);
1091         int addr_per_block = EXT2_ADDR_PER_BLOCK(inode->i_sb);
1092         int offsets[4];
1093         Indirect chain[4];
1094         Indirect *partial;
1095         __le32 nr = 0;
1096         int n;
1097         long iblock;
1098         unsigned blocksize;
1099         blocksize = inode->i_sb->s_blocksize;
1100         iblock = (offset + blocksize-1) >> EXT2_BLOCK_SIZE_BITS(inode->i_sb);
1101 
1102         n = ext2_block_to_path(inode, iblock, offsets, NULL);
1103         if (n == 0)
1104                 return;
1105 
1106         /*
1107          * From here we block out all ext2_get_block() callers who want to
1108          * modify the block allocation tree.
1109          */
1110         mutex_lock(&ei->truncate_mutex);
1111 
1112         if (n == 1) {
1113                 ext2_free_data(inode, i_data+offsets[0],
1114                                         i_data + EXT2_NDIR_BLOCKS);
1115                 goto do_indirects;
1116         }
1117 
1118         partial = ext2_find_shared(inode, n, offsets, chain, &nr);
1119         /* Kill the top of shared branch (already detached) */
1120         if (nr) {
1121                 if (partial == chain)
1122                         mark_inode_dirty(inode);
1123                 else
1124                         mark_buffer_dirty_inode(partial->bh, inode);
1125                 ext2_free_branches(inode, &nr, &nr+1, (chain+n-1) - partial);
1126         }
1127         /* Clear the ends of indirect blocks on the shared branch */
1128         while (partial > chain) {
1129                 ext2_free_branches(inode,
1130                                    partial->p + 1,
1131                                    (__le32*)partial->bh->b_data+addr_per_block,
1132                                    (chain+n-1) - partial);
1133                 mark_buffer_dirty_inode(partial->bh, inode);
1134                 brelse (partial->bh);
1135                 partial--;
1136         }
1137 do_indirects:
1138         /* Kill the remaining (whole) subtrees */
1139         switch (offsets[0]) {
1140                 default:
1141                         nr = i_data[EXT2_IND_BLOCK];
1142                         if (nr) {
1143                                 i_data[EXT2_IND_BLOCK] = 0;
1144                                 mark_inode_dirty(inode);
1145                                 ext2_free_branches(inode, &nr, &nr+1, 1);
1146                         }
1147                 case EXT2_IND_BLOCK:
1148                         nr = i_data[EXT2_DIND_BLOCK];
1149                         if (nr) {
1150                                 i_data[EXT2_DIND_BLOCK] = 0;
1151                                 mark_inode_dirty(inode);
1152                                 ext2_free_branches(inode, &nr, &nr+1, 2);
1153                         }
1154                 case EXT2_DIND_BLOCK:
1155                         nr = i_data[EXT2_TIND_BLOCK];
1156                         if (nr) {
1157                                 i_data[EXT2_TIND_BLOCK] = 0;
1158                                 mark_inode_dirty(inode);
1159                                 ext2_free_branches(inode, &nr, &nr+1, 3);
1160                         }
1161                 case EXT2_TIND_BLOCK:
1162                         ;
1163         }
1164 
1165         ext2_discard_reservation(inode);
1166 
1167         mutex_unlock(&ei->truncate_mutex);
1168 }
1169 
1170 static void ext2_truncate_blocks(struct inode *inode, loff_t offset)
1171 {
1172         /*
1173          * XXX: it seems like a bug here that we don't allow
1174          * IS_APPEND inode to have blocks-past-i_size trimmed off.
1175          * review and fix this.
1176          *
1177          * Also would be nice to be able to handle IO errors and such,
1178          * but that's probably too much to ask.
1179          */
1180         if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
1181             S_ISLNK(inode->i_mode)))
1182                 return;
1183         if (ext2_inode_is_fast_symlink(inode))
1184                 return;
1185         if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
1186                 return;
1187         __ext2_truncate_blocks(inode, offset);
1188 }
1189 
1190 static int ext2_setsize(struct inode *inode, loff_t newsize)
1191 {
1192         int error;
1193 
1194         if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
1195             S_ISLNK(inode->i_mode)))
1196                 return -EINVAL;
1197         if (ext2_inode_is_fast_symlink(inode))
1198                 return -EINVAL;
1199         if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
1200                 return -EPERM;
1201 
1202         inode_dio_wait(inode);
1203 
1204         if (mapping_is_xip(inode->i_mapping))
1205                 error = xip_truncate_page(inode->i_mapping, newsize);
1206         else if (test_opt(inode->i_sb, NOBH))
1207                 error = nobh_truncate_page(inode->i_mapping,
1208                                 newsize, ext2_get_block);
1209         else
1210                 error = block_truncate_page(inode->i_mapping,
1211                                 newsize, ext2_get_block);
1212         if (error)
1213                 return error;
1214 
1215         truncate_setsize(inode, newsize);
1216         __ext2_truncate_blocks(inode, newsize);
1217 
1218         inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
1219         if (inode_needs_sync(inode)) {
1220                 sync_mapping_buffers(inode->i_mapping);
1221                 sync_inode_metadata(inode, 1);
1222         } else {
1223                 mark_inode_dirty(inode);
1224         }
1225 
1226         return 0;
1227 }
1228 
1229 static struct ext2_inode *ext2_get_inode(struct super_block *sb, ino_t ino,
1230                                         struct buffer_head **p)
1231 {
1232         struct buffer_head * bh;
1233         unsigned long block_group;
1234         unsigned long block;
1235         unsigned long offset;
1236         struct ext2_group_desc * gdp;
1237 
1238         *p = NULL;
1239         if ((ino != EXT2_ROOT_INO && ino < EXT2_FIRST_INO(sb)) ||
1240             ino > le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count))
1241                 goto Einval;
1242 
1243         block_group = (ino - 1) / EXT2_INODES_PER_GROUP(sb);
1244         gdp = ext2_get_group_desc(sb, block_group, NULL);
1245         if (!gdp)
1246                 goto Egdp;
1247         /*
1248          * Figure out the offset within the block group inode table
1249          */
1250         offset = ((ino - 1) % EXT2_INODES_PER_GROUP(sb)) * EXT2_INODE_SIZE(sb);
1251         block = le32_to_cpu(gdp->bg_inode_table) +
1252                 (offset >> EXT2_BLOCK_SIZE_BITS(sb));
1253         if (!(bh = sb_bread(sb, block)))
1254                 goto Eio;
1255 
1256         *p = bh;
1257         offset &= (EXT2_BLOCK_SIZE(sb) - 1);
1258         return (struct ext2_inode *) (bh->b_data + offset);
1259 
1260 Einval:
1261         ext2_error(sb, "ext2_get_inode", "bad inode number: %lu",
1262                    (unsigned long) ino);
1263         return ERR_PTR(-EINVAL);
1264 Eio:
1265         ext2_error(sb, "ext2_get_inode",
1266                    "unable to read inode block - inode=%lu, block=%lu",
1267                    (unsigned long) ino, block);
1268 Egdp:
1269         return ERR_PTR(-EIO);
1270 }
1271 
1272 void ext2_set_inode_flags(struct inode *inode)
1273 {
1274         unsigned int flags = EXT2_I(inode)->i_flags;
1275 
1276         inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);
1277         if (flags & EXT2_SYNC_FL)
1278                 inode->i_flags |= S_SYNC;
1279         if (flags & EXT2_APPEND_FL)
1280                 inode->i_flags |= S_APPEND;
1281         if (flags & EXT2_IMMUTABLE_FL)
1282                 inode->i_flags |= S_IMMUTABLE;
1283         if (flags & EXT2_NOATIME_FL)
1284                 inode->i_flags |= S_NOATIME;
1285         if (flags & EXT2_DIRSYNC_FL)
1286                 inode->i_flags |= S_DIRSYNC;
1287 }
1288 
1289 /* Propagate flags from i_flags to EXT2_I(inode)->i_flags */
1290 void ext2_get_inode_flags(struct ext2_inode_info *ei)
1291 {
1292         unsigned int flags = ei->vfs_inode.i_flags;
1293 
1294         ei->i_flags &= ~(EXT2_SYNC_FL|EXT2_APPEND_FL|
1295                         EXT2_IMMUTABLE_FL|EXT2_NOATIME_FL|EXT2_DIRSYNC_FL);
1296         if (flags & S_SYNC)
1297                 ei->i_flags |= EXT2_SYNC_FL;
1298         if (flags & S_APPEND)
1299                 ei->i_flags |= EXT2_APPEND_FL;
1300         if (flags & S_IMMUTABLE)
1301                 ei->i_flags |= EXT2_IMMUTABLE_FL;
1302         if (flags & S_NOATIME)
1303                 ei->i_flags |= EXT2_NOATIME_FL;
1304         if (flags & S_DIRSYNC)
1305                 ei->i_flags |= EXT2_DIRSYNC_FL;
1306 }
1307 
1308 struct inode *ext2_iget (struct super_block *sb, unsigned long ino)
1309 {
1310         struct ext2_inode_info *ei;
1311         struct buffer_head * bh;
1312         struct ext2_inode *raw_inode;
1313         struct inode *inode;
1314         long ret = -EIO;
1315         int n;
1316         uid_t i_uid;
1317         gid_t i_gid;
1318 
1319         inode = iget_locked(sb, ino);
1320         if (!inode)
1321                 return ERR_PTR(-ENOMEM);
1322         if (!(inode->i_state & I_NEW))
1323                 return inode;
1324 
1325         ei = EXT2_I(inode);
1326         ei->i_block_alloc_info = NULL;
1327 
1328         raw_inode = ext2_get_inode(inode->i_sb, ino, &bh);
1329         if (IS_ERR(raw_inode)) {
1330                 ret = PTR_ERR(raw_inode);
1331                 goto bad_inode;
1332         }
1333 
1334         inode->i_mode = le16_to_cpu(raw_inode->i_mode);
1335         i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
1336         i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
1337         if (!(test_opt (inode->i_sb, NO_UID32))) {
1338                 i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
1339                 i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
1340         }
1341         i_uid_write(inode, i_uid);
1342         i_gid_write(inode, i_gid);
1343         set_nlink(inode, le16_to_cpu(raw_inode->i_links_count));
1344         inode->i_size = le32_to_cpu(raw_inode->i_size);
1345         inode->i_atime.tv_sec = (signed)le32_to_cpu(raw_inode->i_atime);
1346         inode->i_ctime.tv_sec = (signed)le32_to_cpu(raw_inode->i_ctime);
1347         inode->i_mtime.tv_sec = (signed)le32_to_cpu(raw_inode->i_mtime);
1348         inode->i_atime.tv_nsec = inode->i_mtime.tv_nsec = inode->i_ctime.tv_nsec = 0;
1349         ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
1350         /* We now have enough fields to check if the inode was active or not.
1351          * This is needed because nfsd might try to access dead inodes
1352          * the test is that same one that e2fsck uses
1353          * NeilBrown 1999oct15
1354          */
1355         if (inode->i_nlink == 0 && (inode->i_mode == 0 || ei->i_dtime)) {
1356                 /* this inode is deleted */
1357                 brelse (bh);
1358                 ret = -ESTALE;
1359                 goto bad_inode;
1360         }
1361         inode->i_blocks = le32_to_cpu(raw_inode->i_blocks);
1362         ei->i_flags = le32_to_cpu(raw_inode->i_flags);
1363         ei->i_faddr = le32_to_cpu(raw_inode->i_faddr);
1364         ei->i_frag_no = raw_inode->i_frag;
1365         ei->i_frag_size = raw_inode->i_fsize;
1366         ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl);
1367         ei->i_dir_acl = 0;
1368         if (S_ISREG(inode->i_mode))
1369                 inode->i_size |= ((__u64)le32_to_cpu(raw_inode->i_size_high)) << 32;
1370         else
1371                 ei->i_dir_acl = le32_to_cpu(raw_inode->i_dir_acl);
1372         ei->i_dtime = 0;
1373         inode->i_generation = le32_to_cpu(raw_inode->i_generation);
1374         ei->i_state = 0;
1375         ei->i_block_group = (ino - 1) / EXT2_INODES_PER_GROUP(inode->i_sb);
1376         ei->i_dir_start_lookup = 0;
1377 
1378         /*
1379          * NOTE! The in-memory inode i_data array is in little-endian order
1380          * even on big-endian machines: we do NOT byteswap the block numbers!
1381          */
1382         for (n = 0; n < EXT2_N_BLOCKS; n++)
1383                 ei->i_data[n] = raw_inode->i_block[n];
1384 
1385         if (S_ISREG(inode->i_mode)) {
1386                 inode->i_op = &ext2_file_inode_operations;
1387                 if (ext2_use_xip(inode->i_sb)) {
1388                         inode->i_mapping->a_ops = &ext2_aops_xip;
1389                         inode->i_fop = &ext2_xip_file_operations;
1390                 } else if (test_opt(inode->i_sb, NOBH)) {
1391                         inode->i_mapping->a_ops = &ext2_nobh_aops;
1392                         inode->i_fop = &ext2_file_operations;
1393                 } else {
1394                         inode->i_mapping->a_ops = &ext2_aops;
1395                         inode->i_fop = &ext2_file_operations;
1396                 }
1397         } else if (S_ISDIR(inode->i_mode)) {
1398                 inode->i_op = &ext2_dir_inode_operations;
1399                 inode->i_fop = &ext2_dir_operations;
1400                 if (test_opt(inode->i_sb, NOBH))
1401                         inode->i_mapping->a_ops = &ext2_nobh_aops;
1402                 else
1403                         inode->i_mapping->a_ops = &ext2_aops;
1404         } else if (S_ISLNK(inode->i_mode)) {
1405                 if (ext2_inode_is_fast_symlink(inode)) {
1406                         inode->i_op = &ext2_fast_symlink_inode_operations;
1407                         nd_terminate_link(ei->i_data, inode->i_size,
1408                                 sizeof(ei->i_data) - 1);
1409                 } else {
1410                         inode->i_op = &ext2_symlink_inode_operations;
1411                         if (test_opt(inode->i_sb, NOBH))
1412                                 inode->i_mapping->a_ops = &ext2_nobh_aops;
1413                         else
1414                                 inode->i_mapping->a_ops = &ext2_aops;
1415                 }
1416         } else {
1417                 inode->i_op = &ext2_special_inode_operations;
1418                 if (raw_inode->i_block[0])
1419                         init_special_inode(inode, inode->i_mode,
1420                            old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
1421                 else 
1422                         init_special_inode(inode, inode->i_mode,
1423                            new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
1424         }
1425         brelse (bh);
1426         ext2_set_inode_flags(inode);
1427         unlock_new_inode(inode);
1428         return inode;
1429         
1430 bad_inode:
1431         iget_failed(inode);
1432         return ERR_PTR(ret);
1433 }
1434 
1435 static int __ext2_write_inode(struct inode *inode, int do_sync)
1436 {
1437         struct ext2_inode_info *ei = EXT2_I(inode);
1438         struct super_block *sb = inode->i_sb;
1439         ino_t ino = inode->i_ino;
1440         uid_t uid = i_uid_read(inode);
1441         gid_t gid = i_gid_read(inode);
1442         struct buffer_head * bh;
1443         struct ext2_inode * raw_inode = ext2_get_inode(sb, ino, &bh);
1444         int n;
1445         int err = 0;
1446 
1447         if (IS_ERR(raw_inode))
1448                 return -EIO;
1449 
1450         /* For fields not not tracking in the in-memory inode,
1451          * initialise them to zero for new inodes. */
1452         if (ei->i_state & EXT2_STATE_NEW)
1453                 memset(raw_inode, 0, EXT2_SB(sb)->s_inode_size);
1454 
1455         ext2_get_inode_flags(ei);
1456         raw_inode->i_mode = cpu_to_le16(inode->i_mode);
1457         if (!(test_opt(sb, NO_UID32))) {
1458                 raw_inode->i_uid_low = cpu_to_le16(low_16_bits(uid));
1459                 raw_inode->i_gid_low = cpu_to_le16(low_16_bits(gid));
1460 /*
1461  * Fix up interoperability with old kernels. Otherwise, old inodes get
1462  * re-used with the upper 16 bits of the uid/gid intact
1463  */
1464                 if (!ei->i_dtime) {
1465                         raw_inode->i_uid_high = cpu_to_le16(high_16_bits(uid));
1466                         raw_inode->i_gid_high = cpu_to_le16(high_16_bits(gid));
1467                 } else {
1468                         raw_inode->i_uid_high = 0;
1469                         raw_inode->i_gid_high = 0;
1470                 }
1471         } else {
1472                 raw_inode->i_uid_low = cpu_to_le16(fs_high2lowuid(uid));
1473                 raw_inode->i_gid_low = cpu_to_le16(fs_high2lowgid(gid));
1474                 raw_inode->i_uid_high = 0;
1475                 raw_inode->i_gid_high = 0;
1476         }
1477         raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
1478         raw_inode->i_size = cpu_to_le32(inode->i_size);
1479         raw_inode->i_atime = cpu_to_le32(inode->i_atime.tv_sec);
1480         raw_inode->i_ctime = cpu_to_le32(inode->i_ctime.tv_sec);
1481         raw_inode->i_mtime = cpu_to_le32(inode->i_mtime.tv_sec);
1482 
1483         raw_inode->i_blocks = cpu_to_le32(inode->i_blocks);
1484         raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
1485         raw_inode->i_flags = cpu_to_le32(ei->i_flags);
1486         raw_inode->i_faddr = cpu_to_le32(ei->i_faddr);
1487         raw_inode->i_frag = ei->i_frag_no;
1488         raw_inode->i_fsize = ei->i_frag_size;
1489         raw_inode->i_file_acl = cpu_to_le32(ei->i_file_acl);
1490         if (!S_ISREG(inode->i_mode))
1491                 raw_inode->i_dir_acl = cpu_to_le32(ei->i_dir_acl);
1492         else {
1493                 raw_inode->i_size_high = cpu_to_le32(inode->i_size >> 32);
1494                 if (inode->i_size > 0x7fffffffULL) {
1495                         if (!EXT2_HAS_RO_COMPAT_FEATURE(sb,
1496                                         EXT2_FEATURE_RO_COMPAT_LARGE_FILE) ||
1497                             EXT2_SB(sb)->s_es->s_rev_level ==
1498                                         cpu_to_le32(EXT2_GOOD_OLD_REV)) {
1499                                /* If this is the first large file
1500                                 * created, add a flag to the superblock.
1501                                 */
1502                                 spin_lock(&EXT2_SB(sb)->s_lock);
1503                                 ext2_update_dynamic_rev(sb);
1504                                 EXT2_SET_RO_COMPAT_FEATURE(sb,
1505                                         EXT2_FEATURE_RO_COMPAT_LARGE_FILE);
1506                                 spin_unlock(&EXT2_SB(sb)->s_lock);
1507                                 ext2_write_super(sb);
1508                         }
1509                 }
1510         }
1511         
1512         raw_inode->i_generation = cpu_to_le32(inode->i_generation);
1513         if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
1514                 if (old_valid_dev(inode->i_rdev)) {
1515                         raw_inode->i_block[0] =
1516                                 cpu_to_le32(old_encode_dev(inode->i_rdev));
1517                         raw_inode->i_block[1] = 0;
1518                 } else {
1519                         raw_inode->i_block[0] = 0;
1520                         raw_inode->i_block[1] =
1521                                 cpu_to_le32(new_encode_dev(inode->i_rdev));
1522                         raw_inode->i_block[2] = 0;
1523                 }
1524         } else for (n = 0; n < EXT2_N_BLOCKS; n++)
1525                 raw_inode->i_block[n] = ei->i_data[n];
1526         mark_buffer_dirty(bh);
1527         if (do_sync) {
1528                 sync_dirty_buffer(bh);
1529                 if (buffer_req(bh) && !buffer_uptodate(bh)) {
1530                         printk ("IO error syncing ext2 inode [%s:%08lx]\n",
1531                                 sb->s_id, (unsigned long) ino);
1532                         err = -EIO;
1533                 }
1534         }
1535         ei->i_state &= ~EXT2_STATE_NEW;
1536         brelse (bh);
1537         return err;
1538 }
1539 
1540 int ext2_write_inode(struct inode *inode, struct writeback_control *wbc)
1541 {
1542         return __ext2_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL);
1543 }
1544 
1545 int ext2_setattr(struct dentry *dentry, struct iattr *iattr)
1546 {
1547         struct inode *inode = dentry->d_inode;
1548         int error;
1549 
1550         error = inode_change_ok(inode, iattr);
1551         if (error)
1552                 return error;
1553 
1554         if (is_quota_modification(inode, iattr))
1555                 dquot_initialize(inode);
1556         if ((iattr->ia_valid & ATTR_UID && !uid_eq(iattr->ia_uid, inode->i_uid)) ||
1557             (iattr->ia_valid & ATTR_GID && !gid_eq(iattr->ia_gid, inode->i_gid))) {
1558                 error = dquot_transfer(inode, iattr);
1559                 if (error)
1560                         return error;
1561         }
1562         if (iattr->ia_valid & ATTR_SIZE && iattr->ia_size != inode->i_size) {
1563                 error = ext2_setsize(inode, iattr->ia_size);
1564                 if (error)
1565                         return error;
1566         }
1567         setattr_copy(inode, iattr);
1568         if (iattr->ia_valid & ATTR_MODE)
1569                 error = ext2_acl_chmod(inode);
1570         mark_inode_dirty(inode);
1571 
1572         return error;
1573 }
1574 

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