dm-bufio.c (f1615bbe9be4def59c3b3eaddb60722efeed16c2) dm-bufio.c (743162013d40ca612b4cb53d3a200dff2d9ab26e)
1/*
2 * Copyright (C) 2009-2011 Red Hat, Inc.
3 *
4 * Author: Mikulas Patocka <mpatocka@redhat.com>
5 *
6 * This file is released under the GPL.
7 */
8

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610 smp_mb__before_atomic();
611 clear_bit(B_WRITING, &b->state);
612 smp_mb__after_atomic();
613
614 wake_up_bit(&b->state, B_WRITING);
615}
616
617/*
1/*
2 * Copyright (C) 2009-2011 Red Hat, Inc.
3 *
4 * Author: Mikulas Patocka <mpatocka@redhat.com>
5 *
6 * This file is released under the GPL.
7 */
8

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610 smp_mb__before_atomic();
611 clear_bit(B_WRITING, &b->state);
612 smp_mb__after_atomic();
613
614 wake_up_bit(&b->state, B_WRITING);
615}
616
617/*
618 * This function is called when wait_on_bit is actually waiting.
619 */
620static int do_io_schedule(void *word)
621{
622 io_schedule();
623
624 return 0;
625}
626
627/*
628 * Initiate a write on a dirty buffer, but don't wait for it.
629 *
630 * - If the buffer is not dirty, exit.
631 * - If there some previous write going on, wait for it to finish (we can't
632 * have two writes on the same buffer simultaneously).
633 * - Submit our write and don't wait on it. We set B_WRITING indicating
634 * that there is a write in progress.
635 */
636static void __write_dirty_buffer(struct dm_buffer *b,
637 struct list_head *write_list)
638{
639 if (!test_bit(B_DIRTY, &b->state))
640 return;
641
642 clear_bit(B_DIRTY, &b->state);
618 * Initiate a write on a dirty buffer, but don't wait for it.
619 *
620 * - If the buffer is not dirty, exit.
621 * - If there some previous write going on, wait for it to finish (we can't
622 * have two writes on the same buffer simultaneously).
623 * - Submit our write and don't wait on it. We set B_WRITING indicating
624 * that there is a write in progress.
625 */
626static void __write_dirty_buffer(struct dm_buffer *b,
627 struct list_head *write_list)
628{
629 if (!test_bit(B_DIRTY, &b->state))
630 return;
631
632 clear_bit(B_DIRTY, &b->state);
643 wait_on_bit_lock(&b->state, B_WRITING,
644 do_io_schedule, TASK_UNINTERRUPTIBLE);
633 wait_on_bit_lock_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE);
645
646 if (!write_list)
647 submit_io(b, WRITE, b->block, write_endio);
648 else
649 list_add_tail(&b->write_list, write_list);
650}
651
652static void __flush_write_list(struct list_head *write_list)

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670 */
671static void __make_buffer_clean(struct dm_buffer *b)
672{
673 BUG_ON(b->hold_count);
674
675 if (!b->state) /* fast case */
676 return;
677
634
635 if (!write_list)
636 submit_io(b, WRITE, b->block, write_endio);
637 else
638 list_add_tail(&b->write_list, write_list);
639}
640
641static void __flush_write_list(struct list_head *write_list)

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659 */
660static void __make_buffer_clean(struct dm_buffer *b)
661{
662 BUG_ON(b->hold_count);
663
664 if (!b->state) /* fast case */
665 return;
666
678 wait_on_bit(&b->state, B_READING, do_io_schedule, TASK_UNINTERRUPTIBLE);
667 wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE);
679 __write_dirty_buffer(b, NULL);
668 __write_dirty_buffer(b, NULL);
680 wait_on_bit(&b->state, B_WRITING, do_io_schedule, TASK_UNINTERRUPTIBLE);
669 wait_on_bit_io(&b->state, B_WRITING, TASK_UNINTERRUPTIBLE);
681}
682
683/*
684 * Find some buffer that is not held by anybody, clean it, unlink it and
685 * return it.
686 */
687static struct dm_buffer *__get_unclaimed_buffer(struct dm_bufio_client *c)
688{

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1025 __flush_write_list(&write_list);
1026
1027 if (!b)
1028 return b;
1029
1030 if (need_submit)
1031 submit_io(b, READ, b->block, read_endio);
1032
670}
671
672/*
673 * Find some buffer that is not held by anybody, clean it, unlink it and
674 * return it.
675 */
676static struct dm_buffer *__get_unclaimed_buffer(struct dm_bufio_client *c)
677{

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1014 __flush_write_list(&write_list);
1015
1016 if (!b)
1017 return b;
1018
1019 if (need_submit)
1020 submit_io(b, READ, b->block, read_endio);
1021
1033 wait_on_bit(&b->state, B_READING, do_io_schedule, TASK_UNINTERRUPTIBLE);
1022 wait_on_bit_io(&b->state, B_READING, TASK_UNINTERRUPTIBLE);
1034
1035 if (b->read_error) {
1036 int error = b->read_error;
1037
1038 dm_bufio_release(b);
1039
1040 return ERR_PTR(error);
1041 }

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1204
1205 BUG_ON(test_bit(B_READING, &b->state));
1206
1207 if (test_bit(B_WRITING, &b->state)) {
1208 if (buffers_processed < c->n_buffers[LIST_DIRTY]) {
1209 dropped_lock = 1;
1210 b->hold_count++;
1211 dm_bufio_unlock(c);
1023
1024 if (b->read_error) {
1025 int error = b->read_error;
1026
1027 dm_bufio_release(b);
1028
1029 return ERR_PTR(error);
1030 }

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1193
1194 BUG_ON(test_bit(B_READING, &b->state));
1195
1196 if (test_bit(B_WRITING, &b->state)) {
1197 if (buffers_processed < c->n_buffers[LIST_DIRTY]) {
1198 dropped_lock = 1;
1199 b->hold_count++;
1200 dm_bufio_unlock(c);
1212 wait_on_bit(&b->state, B_WRITING,
1213 do_io_schedule,
1214 TASK_UNINTERRUPTIBLE);
1201 wait_on_bit_io(&b->state, B_WRITING,
1202 TASK_UNINTERRUPTIBLE);
1215 dm_bufio_lock(c);
1216 b->hold_count--;
1217 } else
1203 dm_bufio_lock(c);
1204 b->hold_count--;
1205 } else
1218 wait_on_bit(&b->state, B_WRITING,
1219 do_io_schedule,
1220 TASK_UNINTERRUPTIBLE);
1206 wait_on_bit_io(&b->state, B_WRITING,
1207 TASK_UNINTERRUPTIBLE);
1221 }
1222
1223 if (!test_bit(B_DIRTY, &b->state) &&
1224 !test_bit(B_WRITING, &b->state))
1225 __relink_lru(b, LIST_CLEAN);
1226
1227 dm_bufio_cond_resched();
1228

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1316 __free_buffer_wake(new);
1317 }
1318
1319 BUG_ON(!b->hold_count);
1320 BUG_ON(test_bit(B_READING, &b->state));
1321
1322 __write_dirty_buffer(b, NULL);
1323 if (b->hold_count == 1) {
1208 }
1209
1210 if (!test_bit(B_DIRTY, &b->state) &&
1211 !test_bit(B_WRITING, &b->state))
1212 __relink_lru(b, LIST_CLEAN);
1213
1214 dm_bufio_cond_resched();
1215

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1303 __free_buffer_wake(new);
1304 }
1305
1306 BUG_ON(!b->hold_count);
1307 BUG_ON(test_bit(B_READING, &b->state));
1308
1309 __write_dirty_buffer(b, NULL);
1310 if (b->hold_count == 1) {
1324 wait_on_bit(&b->state, B_WRITING,
1325 do_io_schedule, TASK_UNINTERRUPTIBLE);
1311 wait_on_bit_io(&b->state, B_WRITING,
1312 TASK_UNINTERRUPTIBLE);
1326 set_bit(B_DIRTY, &b->state);
1327 __unlink_buffer(b);
1328 __link_buffer(b, new_block, LIST_DIRTY);
1329 } else {
1330 sector_t old_block;
1313 set_bit(B_DIRTY, &b->state);
1314 __unlink_buffer(b);
1315 __link_buffer(b, new_block, LIST_DIRTY);
1316 } else {
1317 sector_t old_block;
1331 wait_on_bit_lock(&b->state, B_WRITING,
1332 do_io_schedule, TASK_UNINTERRUPTIBLE);
1318 wait_on_bit_lock_io(&b->state, B_WRITING,
1319 TASK_UNINTERRUPTIBLE);
1333 /*
1334 * Relink buffer to "new_block" so that write_callback
1335 * sees "new_block" as a block number.
1336 * After the write, link the buffer back to old_block.
1337 * All this must be done in bufio lock, so that block number
1338 * change isn't visible to other threads.
1339 */
1340 old_block = b->block;
1341 __unlink_buffer(b);
1342 __link_buffer(b, new_block, b->list_mode);
1343 submit_io(b, WRITE, new_block, write_endio);
1320 /*
1321 * Relink buffer to "new_block" so that write_callback
1322 * sees "new_block" as a block number.
1323 * After the write, link the buffer back to old_block.
1324 * All this must be done in bufio lock, so that block number
1325 * change isn't visible to other threads.
1326 */
1327 old_block = b->block;
1328 __unlink_buffer(b);
1329 __link_buffer(b, new_block, b->list_mode);
1330 submit_io(b, WRITE, new_block, write_endio);
1344 wait_on_bit(&b->state, B_WRITING,
1345 do_io_schedule, TASK_UNINTERRUPTIBLE);
1331 wait_on_bit_io(&b->state, B_WRITING,
1332 TASK_UNINTERRUPTIBLE);
1346 __unlink_buffer(b);
1347 __link_buffer(b, old_block, b->list_mode);
1348 }
1349
1350 dm_bufio_unlock(c);
1351 dm_bufio_release(b);
1352}
1353EXPORT_SYMBOL_GPL(dm_bufio_release_move);

--- 514 unchanged lines hidden --- 		1333 __unlink_buffer(b);
1334 __link_buffer(b, old_block, b->list_mode);
1335 }
1336
1337 dm_bufio_unlock(c);
1338 dm_bufio_release(b);
1339}
1340EXPORT_SYMBOL_GPL(dm_bufio_release_move);

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