/* * helper function for csum removal, this expects the * key to describe the csum pointed to by the path, and it expects * the csum to overlap the range [bytenr, len] * * The csum should not be entirely contained in the range and the * range should not be entirely contained in the csum. * * This calls btrfs_truncate_item with the correct args based on the * overlap, and fixes up the key as required. */ static noinline int truncate_one_csum(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, struct btrfs_key *key, u64 bytenr, u64 len) { struct extent_buffer *leaf; u16 csum_size = btrfs_super_csum_size(&root->fs_info->super_copy); u64 csum_end; u64 end_byte = bytenr + len; u32 blocksize = root->sectorsize; int ret; leaf = path->nodes[0]; csum_end = btrfs_item_size_nr(leaf, path->slots[0]) / csum_size; csum_end *= root->sectorsize; csum_end += key->offset; if (key->offset < bytenr && csum_end <= end_byte) { /* * [ bytenr - len ] * [ ] * [csum ] * A simple truncate off the end of the item */ u32 new_size = (bytenr - key->offset) / blocksize; new_size *= csum_size; ret = btrfs_truncate_item(trans, root, path, new_size, 1); BUG_ON(ret); } else if (key->offset >= bytenr && csum_end > end_byte && end_byte > key->offset) { /* * [ bytenr - len ] * [ ] * [csum ] * we need to truncate from the beginning of the csum */ u32 new_size = (csum_end - end_byte) / blocksize; new_size *= csum_size; ret = btrfs_truncate_item(trans, root, path, new_size, 0); BUG_ON(ret); key->offset = end_byte; ret = btrfs_set_item_key_safe(trans, root, path, key); BUG_ON(ret); } else { BUG(); } return 0; }
/* * this is very complex, but the basic idea is to drop all extents * in the range start - end. hint_block is filled in with a block number * that would be a good hint to the block allocator for this file. * * If an extent intersects the range but is not entirely inside the range * 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) { 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 search_start = start; u64 disk_bytenr = 0; u64 num_bytes = 0; u64 extent_offset = 0; u64 extent_end = 0; int del_nr = 0; int del_slot = 0; int extent_type; int recow; int ret; if (drop_cache) btrfs_drop_extent_cache(inode, start, end - 1, 0); path = btrfs_alloc_path(); if (!path) return -ENOMEM; while (1) { recow = 0; ret = btrfs_lookup_file_extent(trans, root, path, inode->i_ino, search_start, -1); if (ret < 0) break; if (ret > 0 && path->slots[0] > 0 && search_start == start) { leaf = path->nodes[0]; btrfs_item_key_to_cpu(leaf, &key, path->slots[0] - 1); if (key.objectid == inode->i_ino && key.type == BTRFS_EXTENT_DATA_KEY) path->slots[0]--; } ret = 0; next_slot: leaf = path->nodes[0]; if (path->slots[0] >= btrfs_header_nritems(leaf)) { BUG_ON(del_nr > 0); ret = btrfs_next_leaf(root, path); if (ret < 0) break; if (ret > 0) { ret = 0; break; } leaf = path->nodes[0]; recow = 1; } btrfs_item_key_to_cpu(leaf, &key, path->slots[0]); if (key.objectid > inode->i_ino || key.type > BTRFS_EXTENT_DATA_KEY || key.offset >= end) break; fi = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item); extent_type = btrfs_file_extent_type(leaf, fi); if (extent_type == BTRFS_FILE_EXTENT_REG || extent_type == BTRFS_FILE_EXTENT_PREALLOC) { disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi); num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi); extent_offset = btrfs_file_extent_offset(leaf, fi); extent_end = key.offset + btrfs_file_extent_num_bytes(leaf, fi); } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) { extent_end = key.offset + btrfs_file_extent_inline_len(leaf, fi); } else { WARN_ON(1); extent_end = search_start; } if (extent_end <= search_start) { path->slots[0]++; goto next_slot; } search_start = max(key.offset, start); if (recow) { btrfs_release_path(root, path); continue; } /* * | - range to drop - | * | -------- extent -------- | */ if (start > key.offset && end < extent_end) { BUG_ON(del_nr > 0); BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE); memcpy(&new_key, &key, sizeof(new_key)); new_key.offset = start; ret = btrfs_duplicate_item(trans, root, path, &new_key); if (ret == -EAGAIN) { btrfs_release_path(root, path); continue; } if (ret < 0) break; leaf = path->nodes[0]; fi = btrfs_item_ptr(leaf, path->slots[0] - 1, struct btrfs_file_extent_item); btrfs_set_file_extent_num_bytes(leaf, fi, start - key.offset); fi = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item); extent_offset += start - key.offset; btrfs_set_file_extent_offset(leaf, fi, extent_offset); btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - start); btrfs_mark_buffer_dirty(leaf); if (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); BUG_ON(ret); *hint_byte = disk_bytenr; } key.offset = start; } /* * | ---- range to drop ----- | * | -------- extent -------- | */ if (start <= key.offset && end < extent_end) { BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE); memcpy(&new_key, &key, sizeof(new_key)); new_key.offset = end; btrfs_set_item_key_safe(trans, root, path, &new_key); extent_offset += end - key.offset; btrfs_set_file_extent_offset(leaf, fi, extent_offset); btrfs_set_file_extent_num_bytes(leaf, fi, extent_end - end); btrfs_mark_buffer_dirty(leaf); if (disk_bytenr > 0) { inode_sub_bytes(inode, end - key.offset); *hint_byte = disk_bytenr; } break; } search_start = extent_end; /* * | ---- range to drop ----- | * | -------- extent -------- | */ if (start > key.offset && end >= extent_end) { BUG_ON(del_nr > 0); BUG_ON(extent_type == BTRFS_FILE_EXTENT_INLINE); btrfs_set_file_extent_num_bytes(leaf, fi, start - key.offset); btrfs_mark_buffer_dirty(leaf); if (disk_bytenr > 0) { inode_sub_bytes(inode, extent_end - start); *hint_byte = disk_bytenr; } if (end == extent_end) break; path->slots[0]++; goto next_slot; } /* * | ---- range to drop ----- | * | ------ extent ------ | */ if (start <= key.offset && end >= extent_end) { if (del_nr == 0) { del_slot = path->slots[0]; del_nr = 1; } else { BUG_ON(del_slot + del_nr != path->slots[0]); del_nr++; } if (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) { ret = btrfs_free_extent(trans, root, disk_bytenr, num_bytes, 0, root->root_key.objectid, key.objectid, key.offset - extent_offset); BUG_ON(ret); inode_sub_bytes(inode, extent_end - key.offset); *hint_byte = disk_bytenr; } if (end == extent_end) break; if (path->slots[0] + 1 < btrfs_header_nritems(leaf)) { path->slots[0]++; goto next_slot; } ret = btrfs_del_items(trans, root, path, del_slot, del_nr); BUG_ON(ret); del_nr = 0; del_slot = 0; btrfs_release_path(root, path); continue; } BUG_ON(1); }