dm_block_t low_water_blocks;
struct pool_features requested_pf; /* Features requested during table load */
struct pool_features adjusted_pf; /* Features used after adjusting for constituent devices */
+ struct bio flush_bio;
};
/*
while ((bio = bio_list_pop(&bio_completions)))
bio_endio(bio);
- while ((bio = bio_list_pop(&bios)))
- generic_make_request(bio);
+ while ((bio = bio_list_pop(&bios))) {
+ /*
+ * The data device was flushed as part of metadata commit,
+ * so complete redundant flushes immediately.
+ */
+ if (bio->bi_opf & REQ_PREFLUSH)
+ bio_endio(bio);
+ else
+ generic_make_request(bio);
+ }
}
static void do_worker(struct work_struct *ws)
__pool_dec(pt->pool);
dm_put_device(ti, pt->metadata_dev);
dm_put_device(ti, pt->data_dev);
+ bio_uninit(&pt->flush_bio);
kfree(pt);
mutex_unlock(&dm_thin_pool_table.mutex);
dm_table_event(pool->ti->table);
}
+/*
+ * We need to flush the data device **before** committing the metadata.
+ *
+ * This ensures that the data blocks of any newly inserted mappings are
+ * properly written to non-volatile storage and won't be lost in case of a
+ * crash.
+ *
+ * Failure to do so can result in data corruption in the case of internal or
+ * external snapshots and in the case of newly provisioned blocks, when block
+ * zeroing is enabled.
+ */
+static int metadata_pre_commit_callback(void *context)
+{
+ struct pool_c *pt = context;
+ struct bio *flush_bio = &pt->flush_bio;
+
+ bio_reset(flush_bio);
+ bio_set_dev(flush_bio, pt->data_dev->bdev);
+ flush_bio->bi_opf = REQ_OP_WRITE | REQ_PREFLUSH;
+
+ return submit_bio_wait(flush_bio);
+}
+
static sector_t get_dev_size(struct block_device *bdev)
{
return i_size_read(bdev->bd_inode) >> SECTOR_SHIFT;
pt->data_dev = data_dev;
pt->low_water_blocks = low_water_blocks;
pt->adjusted_pf = pt->requested_pf = pf;
+ bio_init(&pt->flush_bio, NULL, 0);
ti->num_flush_bios = 1;
/*
if (r)
goto out_flags_changed;
+ dm_pool_register_pre_commit_callback(pt->pool->pmd,
+ metadata_pre_commit_callback,
+ pt);
+
pt->callbacks.congested_fn = pool_is_congested;
dm_table_add_target_callbacks(ti->table, &pt->callbacks);