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Btrfs: add GPLv2
[deliverable/linux.git] / fs / btrfs / file.c
1 /*
2 * Copyright (C) 2007 Oracle. All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public
6 * License v2 as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public
14 * License along with this program; if not, write to the
15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16 * Boston, MA 021110-1307, USA.
17 */
18
19 #include <linux/module.h>
20 #include <linux/buffer_head.h>
21 #include <linux/fs.h>
22 #include <linux/pagemap.h>
23 #include <linux/highmem.h>
24 #include <linux/time.h>
25 #include <linux/init.h>
26 #include <linux/string.h>
27 #include <linux/smp_lock.h>
28 #include <linux/backing-dev.h>
29 #include <linux/mpage.h>
30 #include <linux/swap.h>
31 #include <linux/writeback.h>
32 #include <linux/statfs.h>
33 #include <linux/compat.h>
34 #include "ctree.h"
35 #include "disk-io.h"
36 #include "transaction.h"
37 #include "btrfs_inode.h"
38 #include "ioctl.h"
39 #include "print-tree.h"
40
41
42 static int btrfs_copy_from_user(loff_t pos, int num_pages, int write_bytes,
43 struct page **prepared_pages,
44 const char __user * buf)
45 {
46 long page_fault = 0;
47 int i;
48 int offset = pos & (PAGE_CACHE_SIZE - 1);
49
50 for (i = 0; i < num_pages && write_bytes > 0; i++, offset = 0) {
51 size_t count = min_t(size_t,
52 PAGE_CACHE_SIZE - offset, write_bytes);
53 struct page *page = prepared_pages[i];
54 fault_in_pages_readable(buf, count);
55
56 /* Copy data from userspace to the current page */
57 kmap(page);
58 page_fault = __copy_from_user(page_address(page) + offset,
59 buf, count);
60 /* Flush processor's dcache for this page */
61 flush_dcache_page(page);
62 kunmap(page);
63 buf += count;
64 write_bytes -= count;
65
66 if (page_fault)
67 break;
68 }
69 return page_fault ? -EFAULT : 0;
70 }
71
72 static void btrfs_drop_pages(struct page **pages, size_t num_pages)
73 {
74 size_t i;
75 for (i = 0; i < num_pages; i++) {
76 if (!pages[i])
77 break;
78 unlock_page(pages[i]);
79 mark_page_accessed(pages[i]);
80 page_cache_release(pages[i]);
81 }
82 }
83
84 static int dirty_and_release_pages(struct btrfs_trans_handle *trans,
85 struct btrfs_root *root,
86 struct file *file,
87 struct page **pages,
88 size_t num_pages,
89 loff_t pos,
90 size_t write_bytes)
91 {
92 int i;
93 int offset;
94 int err = 0;
95 int ret;
96 int this_write;
97 struct inode *inode = file->f_path.dentry->d_inode;
98 struct buffer_head *bh;
99 struct btrfs_file_extent_item *ei;
100
101 for (i = 0; i < num_pages; i++) {
102 offset = pos & (PAGE_CACHE_SIZE -1);
103 this_write = min((size_t)PAGE_CACHE_SIZE - offset, write_bytes);
104 /* FIXME, one block at a time */
105
106 mutex_lock(&root->fs_info->fs_mutex);
107 trans = btrfs_start_transaction(root, 1);
108 btrfs_set_trans_block_group(trans, inode);
109
110 bh = page_buffers(pages[i]);
111
112 if (buffer_mapped(bh) && bh->b_blocknr == 0) {
113 struct btrfs_key key;
114 struct btrfs_path *path;
115 char *ptr;
116 u32 datasize;
117
118 /* create an inline extent, and copy the data in */
119 path = btrfs_alloc_path();
120 BUG_ON(!path);
121 key.objectid = inode->i_ino;
122 key.offset = pages[i]->index << PAGE_CACHE_SHIFT;
123 key.flags = 0;
124 btrfs_set_key_type(&key, BTRFS_EXTENT_DATA_KEY);
125 BUG_ON(write_bytes >= PAGE_CACHE_SIZE);
126 datasize = offset +
127 btrfs_file_extent_calc_inline_size(write_bytes);
128
129 ret = btrfs_insert_empty_item(trans, root, path, &key,
130 datasize);
131 BUG_ON(ret);
132 ei = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]),
133 path->slots[0], struct btrfs_file_extent_item);
134 btrfs_set_file_extent_generation(ei, trans->transid);
135 btrfs_set_file_extent_type(ei,
136 BTRFS_FILE_EXTENT_INLINE);
137 ptr = btrfs_file_extent_inline_start(ei);
138 btrfs_memcpy(root, path->nodes[0]->b_data,
139 ptr, bh->b_data, offset + write_bytes);
140 mark_buffer_dirty(path->nodes[0]);
141 btrfs_free_path(path);
142 } else if (buffer_mapped(bh)) {
143 /* csum the file data */
144 btrfs_csum_file_block(trans, root, inode->i_ino,
145 pages[i]->index << PAGE_CACHE_SHIFT,
146 kmap(pages[i]), PAGE_CACHE_SIZE);
147 kunmap(pages[i]);
148 }
149 SetPageChecked(pages[i]);
150 ret = btrfs_end_transaction(trans, root);
151 BUG_ON(ret);
152 mutex_unlock(&root->fs_info->fs_mutex);
153
154 ret = btrfs_commit_write(file, pages[i], offset,
155 offset + this_write);
156 pos += this_write;
157 if (ret) {
158 err = ret;
159 goto failed;
160 }
161 WARN_ON(this_write > write_bytes);
162 write_bytes -= this_write;
163 }
164 failed:
165 return err;
166 }
167
168 /*
169 * this is very complex, but the basic idea is to drop all extents
170 * in the range start - end. hint_block is filled in with a block number
171 * that would be a good hint to the block allocator for this file.
172 *
173 * If an extent intersects the range but is not entirely inside the range
174 * it is either truncated or split. Anything entirely inside the range
175 * is deleted from the tree.
176 */
177 int btrfs_drop_extents(struct btrfs_trans_handle *trans,
178 struct btrfs_root *root, struct inode *inode,
179 u64 start, u64 end, u64 *hint_block)
180 {
181 int ret;
182 struct btrfs_key key;
183 struct btrfs_leaf *leaf;
184 int slot;
185 struct btrfs_file_extent_item *extent;
186 u64 extent_end = 0;
187 int keep;
188 struct btrfs_file_extent_item old;
189 struct btrfs_path *path;
190 u64 search_start = start;
191 int bookend;
192 int found_type;
193 int found_extent;
194 int found_inline;
195
196 path = btrfs_alloc_path();
197 if (!path)
198 return -ENOMEM;
199 while(1) {
200 btrfs_release_path(root, path);
201 ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino,
202 search_start, -1);
203 if (ret < 0)
204 goto out;
205 if (ret > 0) {
206 if (path->slots[0] == 0) {
207 ret = 0;
208 goto out;
209 }
210 path->slots[0]--;
211 }
212 keep = 0;
213 bookend = 0;
214 found_extent = 0;
215 found_inline = 0;
216 extent = NULL;
217 leaf = btrfs_buffer_leaf(path->nodes[0]);
218 slot = path->slots[0];
219 btrfs_disk_key_to_cpu(&key, &leaf->items[slot].key);
220 if (key.offset >= end || key.objectid != inode->i_ino) {
221 ret = 0;
222 goto out;
223 }
224 if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY) {
225 ret = 0;
226 goto out;
227 }
228 extent = btrfs_item_ptr(leaf, slot,
229 struct btrfs_file_extent_item);
230 found_type = btrfs_file_extent_type(extent);
231 if (found_type == BTRFS_FILE_EXTENT_REG) {
232 extent_end = key.offset +
233 (btrfs_file_extent_num_blocks(extent) <<
234 inode->i_blkbits);
235 found_extent = 1;
236 } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
237 found_inline = 1;
238 extent_end = key.offset +
239 btrfs_file_extent_inline_len(leaf->items + slot);
240 }
241
242 /* we found nothing we can drop */
243 if (!found_extent && !found_inline) {
244 ret = 0;
245 goto out;
246 }
247
248 /* we found nothing inside the range */
249 if (search_start >= extent_end) {
250 ret = 0;
251 goto out;
252 }
253
254 /* FIXME, there's only one inline extent allowed right now */
255 if (found_inline) {
256 u64 mask = root->blocksize - 1;
257 search_start = (extent_end + mask) & ~mask;
258 } else
259 search_start = extent_end;
260
261 if (end < extent_end && end >= key.offset) {
262 if (found_extent) {
263 u64 disk_blocknr =
264 btrfs_file_extent_disk_blocknr(extent);
265 u64 disk_num_blocks =
266 btrfs_file_extent_disk_num_blocks(extent);
267 memcpy(&old, extent, sizeof(old));
268 if (disk_blocknr != 0) {
269 ret = btrfs_inc_extent_ref(trans, root,
270 disk_blocknr, disk_num_blocks);
271 BUG_ON(ret);
272 }
273 }
274 WARN_ON(found_inline);
275 bookend = 1;
276 }
277
278 /* truncate existing extent */
279 if (start > key.offset) {
280 u64 new_num;
281 u64 old_num;
282 keep = 1;
283 WARN_ON(start & (root->blocksize - 1));
284 if (found_extent) {
285 new_num = (start - key.offset) >>
286 inode->i_blkbits;
287 old_num = btrfs_file_extent_num_blocks(extent);
288 *hint_block =
289 btrfs_file_extent_disk_blocknr(extent);
290 if (btrfs_file_extent_disk_blocknr(extent)) {
291 inode->i_blocks -=
292 (old_num - new_num) << 3;
293 }
294 btrfs_set_file_extent_num_blocks(extent,
295 new_num);
296 mark_buffer_dirty(path->nodes[0]);
297 } else {
298 WARN_ON(1);
299 }
300 }
301 /* delete the entire extent */
302 if (!keep) {
303 u64 disk_blocknr = 0;
304 u64 disk_num_blocks = 0;
305 u64 extent_num_blocks = 0;
306 if (found_extent) {
307 disk_blocknr =
308 btrfs_file_extent_disk_blocknr(extent);
309 disk_num_blocks =
310 btrfs_file_extent_disk_num_blocks(extent);
311 extent_num_blocks =
312 btrfs_file_extent_num_blocks(extent);
313 *hint_block =
314 btrfs_file_extent_disk_blocknr(extent);
315 }
316 ret = btrfs_del_item(trans, root, path);
317 BUG_ON(ret);
318 btrfs_release_path(root, path);
319 extent = NULL;
320 if (found_extent && disk_blocknr != 0) {
321 inode->i_blocks -= extent_num_blocks << 3;
322 ret = btrfs_free_extent(trans, root,
323 disk_blocknr,
324 disk_num_blocks, 0);
325 }
326
327 BUG_ON(ret);
328 if (!bookend && search_start >= end) {
329 ret = 0;
330 goto out;
331 }
332 if (!bookend)
333 continue;
334 }
335 /* create bookend, splitting the extent in two */
336 if (bookend && found_extent) {
337 struct btrfs_key ins;
338 ins.objectid = inode->i_ino;
339 ins.offset = end;
340 ins.flags = 0;
341 btrfs_set_key_type(&ins, BTRFS_EXTENT_DATA_KEY);
342
343 btrfs_release_path(root, path);
344 ret = btrfs_insert_empty_item(trans, root, path, &ins,
345 sizeof(*extent));
346 BUG_ON(ret);
347 extent = btrfs_item_ptr(
348 btrfs_buffer_leaf(path->nodes[0]),
349 path->slots[0],
350 struct btrfs_file_extent_item);
351 btrfs_set_file_extent_disk_blocknr(extent,
352 btrfs_file_extent_disk_blocknr(&old));
353 btrfs_set_file_extent_disk_num_blocks(extent,
354 btrfs_file_extent_disk_num_blocks(&old));
355
356 btrfs_set_file_extent_offset(extent,
357 btrfs_file_extent_offset(&old) +
358 ((end - key.offset) >> inode->i_blkbits));
359 WARN_ON(btrfs_file_extent_num_blocks(&old) <
360 (extent_end - end) >> inode->i_blkbits);
361 btrfs_set_file_extent_num_blocks(extent,
362 (extent_end - end) >> inode->i_blkbits);
363
364 btrfs_set_file_extent_type(extent,
365 BTRFS_FILE_EXTENT_REG);
366 btrfs_set_file_extent_generation(extent,
367 btrfs_file_extent_generation(&old));
368 btrfs_mark_buffer_dirty(path->nodes[0]);
369 if (btrfs_file_extent_disk_blocknr(&old) != 0) {
370 inode->i_blocks +=
371 btrfs_file_extent_num_blocks(extent) << 3;
372 }
373 ret = 0;
374 goto out;
375 }
376 }
377 out:
378 btrfs_free_path(path);
379 return ret;
380 }
381
382 /*
383 * this gets pages into the page cache and locks them down
384 */
385 static int prepare_pages(struct btrfs_root *root,
386 struct file *file,
387 struct page **pages,
388 size_t num_pages,
389 loff_t pos,
390 unsigned long first_index,
391 unsigned long last_index,
392 size_t write_bytes,
393 u64 alloc_extent_start)
394 {
395 int i;
396 unsigned long index = pos >> PAGE_CACHE_SHIFT;
397 struct inode *inode = file->f_path.dentry->d_inode;
398 int offset;
399 int err = 0;
400 int this_write;
401 struct buffer_head *bh;
402 struct buffer_head *head;
403 loff_t isize = i_size_read(inode);
404
405 memset(pages, 0, num_pages * sizeof(struct page *));
406
407 for (i = 0; i < num_pages; i++) {
408 pages[i] = grab_cache_page(inode->i_mapping, index + i);
409 if (!pages[i]) {
410 err = -ENOMEM;
411 goto failed_release;
412 }
413 cancel_dirty_page(pages[i], PAGE_CACHE_SIZE);
414 wait_on_page_writeback(pages[i]);
415 offset = pos & (PAGE_CACHE_SIZE -1);
416 this_write = min((size_t)PAGE_CACHE_SIZE - offset, write_bytes);
417 if (!page_has_buffers(pages[i])) {
418 create_empty_buffers(pages[i],
419 root->fs_info->sb->s_blocksize,
420 (1 << BH_Uptodate));
421 }
422 head = page_buffers(pages[i]);
423 bh = head;
424 do {
425 err = btrfs_map_bh_to_logical(root, bh,
426 alloc_extent_start);
427 BUG_ON(err);
428 if (err)
429 goto failed_truncate;
430 bh = bh->b_this_page;
431 if (alloc_extent_start)
432 alloc_extent_start++;
433 } while (bh != head);
434 pos += this_write;
435 WARN_ON(this_write > write_bytes);
436 write_bytes -= this_write;
437 }
438 return 0;
439
440 failed_release:
441 btrfs_drop_pages(pages, num_pages);
442 return err;
443
444 failed_truncate:
445 btrfs_drop_pages(pages, num_pages);
446 if (pos > isize)
447 vmtruncate(inode, isize);
448 return err;
449 }
450
451 static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
452 size_t count, loff_t *ppos)
453 {
454 loff_t pos;
455 size_t num_written = 0;
456 int err = 0;
457 int ret = 0;
458 struct inode *inode = file->f_path.dentry->d_inode;
459 struct btrfs_root *root = BTRFS_I(inode)->root;
460 struct page *pages[8];
461 struct page *pinned[2];
462 unsigned long first_index;
463 unsigned long last_index;
464 u64 start_pos;
465 u64 num_blocks;
466 u64 alloc_extent_start;
467 u64 hint_block;
468 struct btrfs_trans_handle *trans;
469 struct btrfs_key ins;
470 pinned[0] = NULL;
471 pinned[1] = NULL;
472 if (file->f_flags & O_DIRECT)
473 return -EINVAL;
474 pos = *ppos;
475 vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
476 current->backing_dev_info = inode->i_mapping->backing_dev_info;
477 err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
478 if (err)
479 goto out;
480 if (count == 0)
481 goto out;
482 err = remove_suid(file->f_path.dentry);
483 if (err)
484 goto out;
485 file_update_time(file);
486
487 start_pos = pos & ~((u64)PAGE_CACHE_SIZE - 1);
488 num_blocks = (count + pos - start_pos + root->blocksize - 1) >>
489 inode->i_blkbits;
490
491 mutex_lock(&inode->i_mutex);
492 first_index = pos >> PAGE_CACHE_SHIFT;
493 last_index = (pos + count) >> PAGE_CACHE_SHIFT;
494
495 /*
496 * there are lots of better ways to do this, but this code
497 * makes sure the first and last page in the file range are
498 * up to date and ready for cow
499 */
500 if ((pos & (PAGE_CACHE_SIZE - 1))) {
501 pinned[0] = grab_cache_page(inode->i_mapping, first_index);
502 if (!PageUptodate(pinned[0])) {
503 ret = mpage_readpage(pinned[0], btrfs_get_block);
504 BUG_ON(ret);
505 wait_on_page_locked(pinned[0]);
506 } else {
507 unlock_page(pinned[0]);
508 }
509 }
510 if ((pos + count) & (PAGE_CACHE_SIZE - 1)) {
511 pinned[1] = grab_cache_page(inode->i_mapping, last_index);
512 if (!PageUptodate(pinned[1])) {
513 ret = mpage_readpage(pinned[1], btrfs_get_block);
514 BUG_ON(ret);
515 wait_on_page_locked(pinned[1]);
516 } else {
517 unlock_page(pinned[1]);
518 }
519 }
520
521 mutex_lock(&root->fs_info->fs_mutex);
522 trans = btrfs_start_transaction(root, 1);
523 if (!trans) {
524 err = -ENOMEM;
525 mutex_unlock(&root->fs_info->fs_mutex);
526 goto out_unlock;
527 }
528 btrfs_set_trans_block_group(trans, inode);
529 /* FIXME blocksize != 4096 */
530 inode->i_blocks += num_blocks << 3;
531 hint_block = 0;
532
533 /* FIXME...EIEIO, ENOSPC and more */
534
535 /* step one, delete the existing extents in this range */
536 if (start_pos < inode->i_size) {
537 /* FIXME blocksize != pagesize */
538 ret = btrfs_drop_extents(trans, root, inode,
539 start_pos,
540 (pos + count + root->blocksize -1) &
541 ~((u64)root->blocksize - 1),
542 &hint_block);
543 BUG_ON(ret);
544 }
545
546 /* insert any holes we need to create */
547 if (inode->i_size < start_pos) {
548 u64 last_pos_in_file;
549 u64 hole_size;
550 u64 mask = root->blocksize - 1;
551 last_pos_in_file = (inode->i_size + mask) & ~mask;
552 hole_size = (start_pos - last_pos_in_file + mask) & ~mask;
553 hole_size >>= inode->i_blkbits;
554 if (last_pos_in_file < start_pos) {
555 ret = btrfs_insert_file_extent(trans, root,
556 inode->i_ino,
557 last_pos_in_file,
558 0, 0, hole_size);
559 }
560 BUG_ON(ret);
561 }
562
563 /*
564 * either allocate an extent for the new bytes or setup the key
565 * to show we are doing inline data in the extent
566 */
567 if (inode->i_size >= PAGE_CACHE_SIZE || pos + count < inode->i_size ||
568 pos + count - start_pos > BTRFS_MAX_INLINE_DATA_SIZE(root)) {
569 ret = btrfs_alloc_extent(trans, root, inode->i_ino,
570 num_blocks, hint_block, (u64)-1,
571 &ins, 1);
572 BUG_ON(ret);
573 ret = btrfs_insert_file_extent(trans, root, inode->i_ino,
574 start_pos, ins.objectid, ins.offset,
575 ins.offset);
576 BUG_ON(ret);
577 } else {
578 ins.offset = 0;
579 ins.objectid = 0;
580 }
581 BUG_ON(ret);
582 alloc_extent_start = ins.objectid;
583 ret = btrfs_end_transaction(trans, root);
584 mutex_unlock(&root->fs_info->fs_mutex);
585
586 while(count > 0) {
587 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
588 size_t write_bytes = min(count,
589 (size_t)PAGE_CACHE_SIZE - offset);
590 size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
591 PAGE_CACHE_SHIFT;
592
593 memset(pages, 0, sizeof(pages));
594 ret = prepare_pages(root, file, pages, num_pages,
595 pos, first_index, last_index,
596 write_bytes, alloc_extent_start);
597 BUG_ON(ret);
598
599 /* FIXME blocks != pagesize */
600 if (alloc_extent_start)
601 alloc_extent_start += num_pages;
602 ret = btrfs_copy_from_user(pos, num_pages,
603 write_bytes, pages, buf);
604 BUG_ON(ret);
605
606 ret = dirty_and_release_pages(NULL, root, file, pages,
607 num_pages, pos, write_bytes);
608 BUG_ON(ret);
609 btrfs_drop_pages(pages, num_pages);
610
611 buf += write_bytes;
612 count -= write_bytes;
613 pos += write_bytes;
614 num_written += write_bytes;
615
616 balance_dirty_pages_ratelimited(inode->i_mapping);
617 btrfs_btree_balance_dirty(root);
618 cond_resched();
619 }
620 out_unlock:
621 mutex_unlock(&inode->i_mutex);
622 out:
623 if (pinned[0])
624 page_cache_release(pinned[0]);
625 if (pinned[1])
626 page_cache_release(pinned[1]);
627 *ppos = pos;
628 current->backing_dev_info = NULL;
629 mark_inode_dirty(inode);
630 return num_written ? num_written : err;
631 }
632
633 /*
634 * FIXME, do this by stuffing the csum we want in the info hanging off
635 * page->private. For now, verify file csums on read
636 */
637 static int btrfs_read_actor(read_descriptor_t *desc, struct page *page,
638 unsigned long offset, unsigned long size)
639 {
640 char *kaddr;
641 unsigned long left, count = desc->count;
642 struct inode *inode = page->mapping->host;
643
644 if (size > count)
645 size = count;
646
647 if (!PageChecked(page)) {
648 /* FIXME, do it per block */
649 struct btrfs_root *root = BTRFS_I(inode)->root;
650 int ret;
651 struct buffer_head *bh;
652
653 if (page_has_buffers(page)) {
654 bh = page_buffers(page);
655 if (!buffer_mapped(bh)) {
656 SetPageChecked(page);
657 goto checked;
658 }
659 }
660
661 ret = btrfs_csum_verify_file_block(root,
662 page->mapping->host->i_ino,
663 page->index << PAGE_CACHE_SHIFT,
664 kmap(page), PAGE_CACHE_SIZE);
665 if (ret) {
666 if (ret != -ENOENT) {
667 printk("failed to verify ino %lu page %lu ret %d\n",
668 page->mapping->host->i_ino,
669 page->index, ret);
670 memset(page_address(page), 1, PAGE_CACHE_SIZE);
671 flush_dcache_page(page);
672 }
673 }
674 SetPageChecked(page);
675 kunmap(page);
676 }
677 checked:
678 /*
679 * Faults on the destination of a read are common, so do it before
680 * taking the kmap.
681 */
682 if (!fault_in_pages_writeable(desc->arg.buf, size)) {
683 kaddr = kmap_atomic(page, KM_USER0);
684 left = __copy_to_user_inatomic(desc->arg.buf,
685 kaddr + offset, size);
686 kunmap_atomic(kaddr, KM_USER0);
687 if (left == 0)
688 goto success;
689 }
690
691 /* Do it the slow way */
692 kaddr = kmap(page);
693 left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
694 kunmap(page);
695
696 if (left) {
697 size -= left;
698 desc->error = -EFAULT;
699 }
700 success:
701 desc->count = count - size;
702 desc->written += size;
703 desc->arg.buf += size;
704 return size;
705 }
706
707 /**
708 * btrfs_file_aio_read - filesystem read routine, with a mod to csum verify
709 * @iocb: kernel I/O control block
710 * @iov: io vector request
711 * @nr_segs: number of segments in the iovec
712 * @pos: current file position
713 */
714 static ssize_t btrfs_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
715 unsigned long nr_segs, loff_t pos)
716 {
717 struct file *filp = iocb->ki_filp;
718 ssize_t retval;
719 unsigned long seg;
720 size_t count;
721 loff_t *ppos = &iocb->ki_pos;
722
723 count = 0;
724 for (seg = 0; seg < nr_segs; seg++) {
725 const struct iovec *iv = &iov[seg];
726
727 /*
728 * If any segment has a negative length, or the cumulative
729 * length ever wraps negative then return -EINVAL.
730 */
731 count += iv->iov_len;
732 if (unlikely((ssize_t)(count|iv->iov_len) < 0))
733 return -EINVAL;
734 if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len))
735 continue;
736 if (seg == 0)
737 return -EFAULT;
738 nr_segs = seg;
739 count -= iv->iov_len; /* This segment is no good */
740 break;
741 }
742 retval = 0;
743 if (count) {
744 for (seg = 0; seg < nr_segs; seg++) {
745 read_descriptor_t desc;
746
747 desc.written = 0;
748 desc.arg.buf = iov[seg].iov_base;
749 desc.count = iov[seg].iov_len;
750 if (desc.count == 0)
751 continue;
752 desc.error = 0;
753 do_generic_file_read(filp, ppos, &desc,
754 btrfs_read_actor);
755 retval += desc.written;
756 if (desc.error) {
757 retval = retval ?: desc.error;
758 break;
759 }
760 }
761 }
762 return retval;
763 }
764
765 static int btrfs_sync_file(struct file *file,
766 struct dentry *dentry, int datasync)
767 {
768 struct inode *inode = dentry->d_inode;
769 struct btrfs_root *root = BTRFS_I(inode)->root;
770 int ret;
771 struct btrfs_trans_handle *trans;
772
773 /*
774 * FIXME, use inode generation number to check if we can skip the
775 * commit
776 */
777 mutex_lock(&root->fs_info->fs_mutex);
778 trans = btrfs_start_transaction(root, 1);
779 if (!trans) {
780 ret = -ENOMEM;
781 goto out;
782 }
783 ret = btrfs_commit_transaction(trans, root);
784 mutex_unlock(&root->fs_info->fs_mutex);
785 out:
786 return ret > 0 ? EIO : ret;
787 }
788
789 struct file_operations btrfs_file_operations = {
790 .llseek = generic_file_llseek,
791 .read = do_sync_read,
792 .aio_read = btrfs_file_aio_read,
793 .write = btrfs_file_write,
794 .mmap = generic_file_mmap,
795 .open = generic_file_open,
796 .ioctl = btrfs_ioctl,
797 .fsync = btrfs_sync_file,
798 #ifdef CONFIG_COMPAT
799 .compat_ioctl = btrfs_compat_ioctl,
800 #endif
801 };
802
Linux kernel - Deliverables
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