diff options
Diffstat (limited to 'fs/btrfs/file.c')
-rw-r--r-- | fs/btrfs/file.c | 449 |
1 files changed, 409 insertions, 40 deletions
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 5caf285c6e4..9ab1bed8811 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -39,6 +39,7 @@ #include "tree-log.h" #include "locking.h" #include "compat.h" +#include "volumes.h" /* * when auto defrag is enabled we @@ -458,14 +459,15 @@ int btrfs_dirty_pages(struct btrfs_root *root, struct inode *inode, * this drops all the extents in the cache that intersect the range * [start, end]. Existing extents are split as required. */ -int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end, - int skip_pinned) +void btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end, + int skip_pinned) { struct extent_map *em; struct extent_map *split = NULL; struct extent_map *split2 = NULL; struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree; u64 len = end - start + 1; + u64 gen; int ret; int testend = 1; unsigned long flags; @@ -477,11 +479,14 @@ int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end, testend = 0; } while (1) { + int no_splits = 0; + if (!split) split = alloc_extent_map(); if (!split2) split2 = alloc_extent_map(); - BUG_ON(!split || !split2); /* -ENOMEM */ + if (!split || !split2) + no_splits = 1; write_lock(&em_tree->lock); em = lookup_extent_mapping(em_tree, start, len); @@ -490,6 +495,7 @@ int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end, break; } flags = em->flags; + gen = em->generation; if (skip_pinned && test_bit(EXTENT_FLAG_PINNED, &em->flags)) { if (testend && em->start + em->len >= start + len) { free_extent_map(em); @@ -506,6 +512,8 @@ int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end, compressed = test_bit(EXTENT_FLAG_COMPRESSED, &em->flags); clear_bit(EXTENT_FLAG_PINNED, &em->flags); remove_extent_mapping(em_tree, em); + if (no_splits) + goto next; if (em->block_start < EXTENT_MAP_LAST_BYTE && em->start < start) { @@ -518,12 +526,13 @@ int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end, split->block_len = em->block_len; else split->block_len = split->len; - + split->generation = gen; split->bdev = em->bdev; split->flags = flags; split->compress_type = em->compress_type; ret = add_extent_mapping(em_tree, split); BUG_ON(ret); /* Logic error */ + list_move(&split->list, &em_tree->modified_extents); free_extent_map(split); split = split2; split2 = NULL; @@ -537,6 +546,7 @@ int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end, split->bdev = em->bdev; split->flags = flags; split->compress_type = em->compress_type; + split->generation = gen; if (compressed) { split->block_len = em->block_len; @@ -550,9 +560,11 @@ int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end, ret = add_extent_mapping(em_tree, split); BUG_ON(ret); /* Logic error */ + list_move(&split->list, &em_tree->modified_extents); free_extent_map(split); split = NULL; } +next: write_unlock(&em_tree->lock); /* once for us */ @@ -564,7 +576,6 @@ int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end, free_extent_map(split); if (split2) free_extent_map(split2); - return 0; } /* @@ -576,13 +587,13 @@ int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end, * it is either truncated or split. Anything entirely inside the range * is deleted from the tree. */ -int btrfs_drop_extents(struct btrfs_trans_handle *trans, struct inode *inode, - u64 start, u64 end, u64 *hint_byte, int drop_cache) +int __btrfs_drop_extents(struct btrfs_trans_handle *trans, + struct btrfs_root *root, struct inode *inode, + struct btrfs_path *path, u64 start, u64 end, + u64 *drop_end, int drop_cache) { - struct btrfs_root *root = BTRFS_I(inode)->root; struct extent_buffer *leaf; struct btrfs_file_extent_item *fi; - struct btrfs_path *path; struct btrfs_key key; struct btrfs_key new_key; u64 ino = btrfs_ino(inode); @@ -597,14 +608,12 @@ int btrfs_drop_extents(struct btrfs_trans_handle *trans, struct inode *inode, int recow; int ret; int modify_tree = -1; + int update_refs = (root->ref_cows || root == root->fs_info->tree_root); + int found = 0; if (drop_cache) btrfs_drop_extent_cache(inode, start, end - 1, 0); - path = btrfs_alloc_path(); - if (!path) - return -ENOMEM; - if (start >= BTRFS_I(inode)->disk_i_size) modify_tree = 0; @@ -666,6 +675,7 @@ next_slot: goto next_slot; } + found = 1; search_start = max(key.offset, start); if (recow || !modify_tree) { modify_tree = -1; @@ -707,14 +717,13 @@ next_slot: extent_end - start); btrfs_mark_buffer_dirty(leaf); - if (disk_bytenr > 0) { + if (update_refs && disk_bytenr > 0) { ret = btrfs_inc_extent_ref(trans, root, disk_bytenr, num_bytes, 0, root->root_key.objectid, new_key.objectid, start - extent_offset, 0); BUG_ON(ret); /* -ENOMEM */ - *hint_byte = disk_bytenr; } key.offset = start; } @@ -734,10 +743,8 @@ next_slot: btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - end); btrfs_mark_buffer_dirty(leaf); - if (disk_bytenr > 0) { + if (update_refs && disk_bytenr > 0) inode_sub_bytes(inode, end - key.offset); - *hint_byte = disk_bytenr; - } break; } @@ -753,10 +760,8 @@ next_slot: btrfs_set_file_extent_num_bytes(leaf, fi, start - key.offset); btrfs_mark_buffer_dirty(leaf); - if (disk_bytenr > 0) { + if (update_refs && disk_bytenr > 0) inode_sub_bytes(inode, extent_end - start); - *hint_byte = disk_bytenr; - } if (end == extent_end) break; @@ -777,12 +782,13 @@ next_slot: del_nr++; } - if (extent_type == BTRFS_FILE_EXTENT_INLINE) { + if (update_refs && + extent_type == BTRFS_FILE_EXTENT_INLINE) { inode_sub_bytes(inode, extent_end - key.offset); extent_end = ALIGN(extent_end, root->sectorsize); - } else if (disk_bytenr > 0) { + } else if (update_refs && disk_bytenr > 0) { ret = btrfs_free_extent(trans, root, disk_bytenr, num_bytes, 0, root->root_key.objectid, @@ -791,7 +797,6 @@ next_slot: BUG_ON(ret); /* -ENOMEM */ inode_sub_bytes(inode, extent_end - key.offset); - *hint_byte = disk_bytenr; } if (end == extent_end) @@ -806,7 +811,7 @@ next_slot: del_nr); if (ret) { btrfs_abort_transaction(trans, root, ret); - goto out; + break; } del_nr = 0; @@ -825,7 +830,24 @@ next_slot: btrfs_abort_transaction(trans, root, ret); } -out: + if (drop_end) + *drop_end = found ? min(end, extent_end) : end; + btrfs_release_path(path); + return ret; +} + +int btrfs_drop_extents(struct btrfs_trans_handle *trans, + struct btrfs_root *root, struct inode *inode, u64 start, + u64 end, int drop_cache) +{ + struct btrfs_path *path; + int ret; + + path = btrfs_alloc_path(); + if (!path) + return -ENOMEM; + ret = __btrfs_drop_extents(trans, root, inode, path, start, end, NULL, + drop_cache); btrfs_free_path(path); return ret; } @@ -892,8 +914,6 @@ int btrfs_mark_extent_written(struct btrfs_trans_handle *trans, int ret; u64 ino = btrfs_ino(inode); - btrfs_drop_extent_cache(inode, start, end - 1, 0); - path = btrfs_alloc_path(); if (!path) return -ENOMEM; @@ -935,12 +955,16 @@ again: btrfs_set_item_key_safe(trans, root, path, &new_key); fi = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item); + btrfs_set_file_extent_generation(leaf, fi, + trans->transid); btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - end); btrfs_set_file_extent_offset(leaf, fi, end - orig_offset); fi = btrfs_item_ptr(leaf, path->slots[0] - 1, struct btrfs_file_extent_item); + btrfs_set_file_extent_generation(leaf, fi, + trans->transid); btrfs_set_file_extent_num_bytes(leaf, fi, end - other_start); btrfs_mark_buffer_dirty(leaf); @@ -958,12 +982,16 @@ again: struct btrfs_file_extent_item); btrfs_set_file_extent_num_bytes(leaf, fi, start - key.offset); + btrfs_set_file_extent_generation(leaf, fi, + trans->transid); path->slots[0]++; new_key.offset = start; btrfs_set_item_key_safe(trans, root, path, &new_key); fi = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item); + btrfs_set_file_extent_generation(leaf, fi, + trans->transid); btrfs_set_file_extent_num_bytes(leaf, fi, other_end - start); btrfs_set_file_extent_offset(leaf, fi, @@ -991,12 +1019,14 @@ again: leaf = path->nodes[0]; fi = btrfs_item_ptr(leaf, path->slots[0] - 1, struct btrfs_file_extent_item); + btrfs_set_file_extent_generation(leaf, fi, trans->transid); btrfs_set_file_extent_num_bytes(leaf, fi, split - key.offset); fi = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item); + btrfs_set_file_extent_generation(leaf, fi, trans->transid); btrfs_set_file_extent_offset(leaf, fi, split - orig_offset); btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - split); @@ -1056,12 +1086,14 @@ again: struct btrfs_file_extent_item); btrfs_set_file_extent_type(leaf, fi, BTRFS_FILE_EXTENT_REG); + btrfs_set_file_extent_generation(leaf, fi, trans->transid); btrfs_mark_buffer_dirty(leaf); } else { fi = btrfs_item_ptr(leaf, del_slot - 1, struct btrfs_file_extent_item); btrfs_set_file_extent_type(leaf, fi, BTRFS_FILE_EXTENT_REG); + btrfs_set_file_extent_generation(leaf, fi, trans->transid); btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - key.offset); btrfs_mark_buffer_dirty(leaf); @@ -1173,8 +1205,8 @@ again: clear_extent_bit(&BTRFS_I(inode)->io_tree, start_pos, last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC | - EXTENT_DO_ACCOUNTING, 0, 0, &cached_state, - GFP_NOFS); + EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG, + 0, 0, &cached_state, GFP_NOFS); unlock_extent_cached(&BTRFS_I(inode)->io_tree, start_pos, last_pos - 1, &cached_state, GFP_NOFS); @@ -1514,16 +1546,24 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync) trace_btrfs_sync_file(file, datasync); + /* + * We write the dirty pages in the range and wait until they complete + * out of the ->i_mutex. If so, we can flush the dirty pages by + * multi-task, and make the performance up. + */ + ret = filemap_write_and_wait_range(inode->i_mapping, start, end); + if (ret) + return ret; + mutex_lock(&inode->i_mutex); /* - * we wait first, since the writeback may change the inode, also wait - * ordered range does a filemape_write_and_wait_range which is why we - * don't do it above like other file systems. + * We flush the dirty pages again to avoid some dirty pages in the + * range being left. */ - root->log_batch++; + atomic_inc(&root->log_batch); btrfs_wait_ordered_range(inode, start, end); - root->log_batch++; + atomic_inc(&root->log_batch); /* * check the transaction that last modified this inode @@ -1544,6 +1584,14 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync) BTRFS_I(inode)->last_trans <= root->fs_info->last_trans_committed) { BTRFS_I(inode)->last_trans = 0; + + /* + * We'v had everything committed since the last time we were + * modified so clear this flag in case it was set for whatever + * reason, it's no longer relevant. + */ + clear_bit(BTRFS_INODE_NEEDS_FULL_SYNC, + &BTRFS_I(inode)->runtime_flags); mutex_unlock(&inode->i_mutex); goto out; } @@ -1599,6 +1647,7 @@ out: static const struct vm_operations_struct btrfs_file_vm_ops = { .fault = filemap_fault, .page_mkwrite = btrfs_page_mkwrite, + .remap_pages = generic_file_remap_pages, }; static int btrfs_file_mmap(struct file *filp, struct vm_area_struct *vma) @@ -1610,11 +1659,328 @@ static int btrfs_file_mmap(struct file *filp, struct vm_area_struct *vma) file_accessed(filp); vma->vm_ops = &btrfs_file_vm_ops; - vma->vm_flags |= VM_CAN_NONLINEAR; return 0; } +static int hole_mergeable(struct inode *inode, struct extent_buffer *leaf, + int slot, u64 start, u64 end) +{ + struct btrfs_file_extent_item *fi; + struct btrfs_key key; + + if (slot < 0 || slot >= btrfs_header_nritems(leaf)) + return 0; + + btrfs_item_key_to_cpu(leaf, &key, slot); + if (key.objectid != btrfs_ino(inode) || + key.type != BTRFS_EXTENT_DATA_KEY) + return 0; + + fi = btrfs_item_ptr(leaf, slot, struct btrfs_file_extent_item); + + if (btrfs_file_extent_type(leaf, fi) != BTRFS_FILE_EXTENT_REG) + return 0; + + if (btrfs_file_extent_disk_bytenr(leaf, fi)) + return 0; + + if (key.offset == end) + return 1; + if (key.offset + btrfs_file_extent_num_bytes(leaf, fi) == start) + return 1; + return 0; +} + +static int fill_holes(struct btrfs_trans_handle *trans, struct inode *inode, + struct btrfs_path *path, u64 offset, u64 end) +{ + struct btrfs_root *root = BTRFS_I(inode)->root; + struct extent_buffer *leaf; + struct btrfs_file_extent_item *fi; + struct extent_map *hole_em; + struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree; + struct btrfs_key key; + int ret; + + key.objectid = btrfs_ino(inode); + key.type = BTRFS_EXTENT_DATA_KEY; + key.offset = offset; + + + ret = btrfs_search_slot(trans, root, &key, path, 0, 1); + if (ret < 0) + return ret; + BUG_ON(!ret); + + leaf = path->nodes[0]; + if (hole_mergeable(inode, leaf, path->slots[0]-1, offset, end)) { + u64 num_bytes; + + path->slots[0]--; + fi = btrfs_item_ptr(leaf, path->slots[0], + struct btrfs_file_extent_item); + num_bytes = btrfs_file_extent_num_bytes(leaf, fi) + + end - offset; + btrfs_set_file_extent_num_bytes(leaf, fi, num_bytes); + btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes); + btrfs_set_file_extent_offset(leaf, fi, 0); + btrfs_mark_buffer_dirty(leaf); + goto out; + } + + if (hole_mergeable(inode, leaf, path->slots[0]+1, offset, end)) { + u64 num_bytes; + + path->slots[0]++; + key.offset = offset; + btrfs_set_item_key_safe(trans, root, path, &key); + fi = btrfs_item_ptr(leaf, path->slots[0], + struct btrfs_file_extent_item); + num_bytes = btrfs_file_extent_num_bytes(leaf, fi) + end - + offset; + btrfs_set_file_extent_num_bytes(leaf, fi, num_bytes); + btrfs_set_file_extent_ram_bytes(leaf, fi, num_bytes); + btrfs_set_file_extent_offset(leaf, fi, 0); + btrfs_mark_buffer_dirty(leaf); + goto out; + } + btrfs_release_path(path); + + ret = btrfs_insert_file_extent(trans, root, btrfs_ino(inode), offset, + 0, 0, end - offset, 0, end - offset, + 0, 0, 0); + if (ret) + return ret; + +out: + btrfs_release_path(path); + + hole_em = alloc_extent_map(); + if (!hole_em) { + btrfs_drop_extent_cache(inode, offset, end - 1, 0); + set_bit(BTRFS_INODE_NEEDS_FULL_SYNC, + &BTRFS_I(inode)->runtime_flags); + } else { + hole_em->start = offset; + hole_em->len = end - offset; + hole_em->orig_start = offset; + + hole_em->block_start = EXTENT_MAP_HOLE; + hole_em->block_len = 0; + hole_em->bdev = root->fs_info->fs_devices->latest_bdev; + hole_em->compress_type = BTRFS_COMPRESS_NONE; + hole_em->generation = trans->transid; + + do { + btrfs_drop_extent_cache(inode, offset, end - 1, 0); + write_lock(&em_tree->lock); + ret = add_extent_mapping(em_tree, hole_em); + if (!ret) + list_move(&hole_em->list, + &em_tree->modified_extents); + write_unlock(&em_tree->lock); + } while (ret == -EEXIST); + free_extent_map(hole_em); + if (ret) + set_bit(BTRFS_INODE_NEEDS_FULL_SYNC, + &BTRFS_I(inode)->runtime_flags); + } + + return 0; +} + +static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len) +{ + struct btrfs_root *root = BTRFS_I(inode)->root; + struct extent_state *cached_state = NULL; + struct btrfs_path *path; + struct btrfs_block_rsv *rsv; + struct btrfs_trans_handle *trans; + u64 mask = BTRFS_I(inode)->root->sectorsize - 1; + u64 lockstart = (offset + mask) & ~mask; + u64 lockend = ((offset + len) & ~mask) - 1; + u64 cur_offset = lockstart; + u64 min_size = btrfs_calc_trunc_metadata_size(root, 1); + u64 drop_end; + unsigned long nr; + int ret = 0; + int err = 0; + bool same_page = (offset >> PAGE_CACHE_SHIFT) == + ((offset + len) >> PAGE_CACHE_SHIFT); + + btrfs_wait_ordered_range(inode, offset, len); + + mutex_lock(&inode->i_mutex); + if (offset >= inode->i_size) { + mutex_unlock(&inode->i_mutex); + return 0; + } + + /* + * Only do this if we are in the same page and we aren't doing the + * entire page. + */ + if (same_page && len < PAGE_CACHE_SIZE) { + ret = btrfs_truncate_page(inode, offset, len, 0); + mutex_unlock(&inode->i_mutex); + return ret; + } + + /* zero back part of the first page */ + ret = btrfs_truncate_page(inode, offset, 0, 0); + if (ret) { + mutex_unlock(&inode->i_mutex); + return ret; + } + + /* zero the front end of the last page */ + ret = btrfs_truncate_page(inode, offset + len, 0, 1); + if (ret) { + mutex_unlock(&inode->i_mutex); + return ret; + } + + if (lockend < lockstart) { + mutex_unlock(&inode->i_mutex); + return 0; + } + + while (1) { + struct btrfs_ordered_extent *ordered; + + truncate_pagecache_range(inode, lockstart, lockend); + + lock_extent_bits(&BTRFS_I(inode)->io_tree, lockstart, lockend, + 0, &cached_state); + ordered = btrfs_lookup_first_ordered_extent(inode, lockend); + + /* + * We need to make sure we have no ordered extents in this range + * and nobody raced in and read a page in this range, if we did + * we need to try again. + */ + if ((!ordered || + (ordered->file_offset + ordered->len < lockstart || + ordered->file_offset > lockend)) && + !test_range_bit(&BTRFS_I(inode)->io_tree, lockstart, + lockend, EXTENT_UPTODATE, 0, + cached_state)) { + if (ordered) + btrfs_put_ordered_extent(ordered); + break; + } + if (ordered) + btrfs_put_ordered_extent(ordered); + unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, + lockend, &cached_state, GFP_NOFS); + btrfs_wait_ordered_range(inode, lockstart, + lockend - lockstart + 1); + } + + path = btrfs_alloc_path(); + if (!path) { + ret = -ENOMEM; + goto out; + } + + rsv = btrfs_alloc_block_rsv(root, BTRFS_BLOCK_RSV_TEMP); + if (!rsv) { + ret = -ENOMEM; + goto out_free; + } + rsv->size = btrfs_calc_trunc_metadata_size(root, 1); + rsv->failfast = 1; + + /* + * 1 - update the inode + * 1 - removing the extents in the range + * 1 - adding the hole extent + */ + trans = btrfs_start_transaction(root, 3); + if (IS_ERR(trans)) { + err = PTR_ERR(trans); + goto out_free; + } + + ret = btrfs_block_rsv_migrate(&root->fs_info->trans_block_rsv, rsv, + min_size); + BUG_ON(ret); + trans->block_rsv = rsv; + + while (cur_offset < lockend) { + ret = __btrfs_drop_extents(trans, root, inode, path, + cur_offset, lockend + 1, + &drop_end, 1); + if (ret != -ENOSPC) + break; + + trans->block_rsv = &root->fs_info->trans_block_rsv; + + ret = fill_holes(trans, inode, path, cur_offset, drop_end); + if (ret) { + err = ret; + break; + } + + cur_offset = drop_end; + + ret = btrfs_update_inode(trans, root, inode); + if (ret) { + err = ret; + break; + } + + nr = trans->blocks_used; + btrfs_end_transaction(trans, root); + btrfs_btree_balance_dirty(root, nr); + + trans = btrfs_start_transaction(root, 3); + if (IS_ERR(trans)) { + ret = PTR_ERR(trans); + trans = NULL; + break; + } + + ret = btrfs_block_rsv_migrate(&root->fs_info->trans_block_rsv, + rsv, min_size); + BUG_ON(ret); /* shouldn't happen */ + trans->block_rsv = rsv; + } + + if (ret) { + err = ret; + goto out_trans; + } + + trans->block_rsv = &root->fs_info->trans_block_rsv; + ret = fill_holes(trans, inode, path, cur_offset, drop_end); + if (ret) { + err = ret; + goto out_trans; + } + +out_trans: + if (!trans) + goto out_free; + + trans->block_rsv = &root->fs_info->trans_block_rsv; + ret = btrfs_update_inode(trans, root, inode); + nr = trans->blocks_used; + btrfs_end_transaction(trans, root); + btrfs_btree_balance_dirty(root, nr); +out_free: + btrfs_free_path(path); + btrfs_free_block_rsv(root, rsv); +out: + unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend, + &cached_state, GFP_NOFS); + mutex_unlock(&inode->i_mutex); + if (ret && !err) + err = ret; + return err; +} + static long btrfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len) { @@ -1633,15 +1999,18 @@ static long btrfs_fallocate(struct file *file, int mode, alloc_start = offset & ~mask; alloc_end = (offset + len + mask) & ~mask; - /* We only support the FALLOC_FL_KEEP_SIZE mode */ - if (mode & ~FALLOC_FL_KEEP_SIZE) + /* Make sure we aren't being give some crap mode */ + if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE)) return -EOPNOTSUPP; + if (mode & FALLOC_FL_PUNCH_HOLE) + return btrfs_punch_hole(inode, offset, len); + /* * Make sure we have enough space before we do the * allocation. */ - ret = btrfs_check_data_free_space(inode, len); + ret = btrfs_check_data_free_space(inode, alloc_end - alloc_start + 1); if (ret) return ret; @@ -1748,7 +2117,7 @@ static long btrfs_fallocate(struct file *file, int mode, out: mutex_unlock(&inode->i_mutex); /* Let go of our reservation. */ - btrfs_free_reserved_data_space(inode, len); + btrfs_free_reserved_data_space(inode, alloc_end - alloc_start + 1); return ret; } |