Introduce a new function: btrfs_read_one_data_csum(), to read out a csum for a sectorsize.
This is quite useful for read out data csum so we don't need to do it using open code. Signed-off-by: Qu Wenruo <[email protected]> --- Makefile.in | 2 +- csum.c | 96 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ctree.h | 3 ++ 3 files changed, 100 insertions(+), 1 deletion(-) create mode 100644 csum.c diff --git a/Makefile.in b/Makefile.in index c3f0eeda..bb619bfe 100644 --- a/Makefile.in +++ b/Makefile.in @@ -99,7 +99,7 @@ objects = ctree.o disk-io.o kernel-lib/radix-tree.o extent-tree.o print-tree.o \ qgroup.o free-space-cache.o kernel-lib/list_sort.o props.o \ ulist.o qgroup-verify.o backref.o string-table.o task-utils.o \ inode.o file.o find-root.o free-space-tree.o help.o send-dump.o \ - kernel-lib/tables.o kernel-lib/raid56.o + kernel-lib/tables.o kernel-lib/raid56.o csum.o cmds_objects = cmds-subvolume.o cmds-filesystem.o cmds-device.o cmds-scrub.o \ cmds-inspect.o cmds-balance.o cmds-send.o cmds-receive.o \ cmds-quota.o cmds-qgroup.o cmds-replace.o cmds-check.o \ diff --git a/csum.c b/csum.c new file mode 100644 index 00000000..53195eaf --- /dev/null +++ b/csum.c @@ -0,0 +1,96 @@ +/* + * Copyright (C) 2016 Fujitsu. All rights reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public + * License v2 as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + * + * You should have received a copy of the GNU General Public + * License along with this program; if not, write to the + * Free Software Foundation, Inc., 59 Temple Place - Suite 330, + * Boston, MA 021110-1307, USA. + */ + +#include "ctree.h" +#include "utils.h" +/* + * TODO: + * 1) Add write support for csum + * So we can write new data extents and add csum into csum tree + * 2) Add csum range search function + * So we don't need to search csum tree in a per-sectorsize loop. + */ + +int btrfs_read_one_data_csum(struct btrfs_fs_info *fs_info, u64 bytenr, + void *csum_ret) +{ + struct btrfs_path *path; + struct btrfs_key key; + struct btrfs_root *csum_root = fs_info->csum_root; + u32 item_offset; + u32 item_size; + u32 final_offset; + u32 sectorsize = fs_info->tree_root->sectorsize; + u16 csum_size = btrfs_super_csum_size(fs_info->super_copy); + int ret; + + if (!csum_ret) { + error("wrong parameter for %s", __func__); + return -EINVAL; + } + path = btrfs_alloc_path(); + if (!path) + return -ENOMEM; + + key.objectid = BTRFS_EXTENT_CSUM_OBJECTID; + key.type = BTRFS_EXTENT_CSUM_KEY; + key.offset = bytenr; + + ret = btrfs_search_slot(NULL, csum_root, &key, path, 0, 0); + if (ret < 0) + goto out; + if (ret == 0) { + btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]); + if (!IS_ALIGNED(key.offset, sectorsize)) { + error("csum item bytenr %llu is not aligned to %u", + key.offset, sectorsize); + ret = -EIO; + goto out; + } + u32 offset = btrfs_item_ptr_offset(path->nodes[0], + path->slots[0]); + + read_extent_buffer(path->nodes[0], csum_ret, offset, csum_size); + goto out; + } + ret = btrfs_previous_item(csum_root, path, BTRFS_EXTENT_CSUM_OBJECTID, + BTRFS_EXTENT_CSUM_KEY); + if (ret) + goto out; + btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]); + if (!IS_ALIGNED(key.offset, sectorsize)) { + error("csum item bytenr %llu is not aligned to %u", + key.offset, sectorsize); + ret = -EIO; + goto out; + } + item_offset = btrfs_item_ptr_offset(path->nodes[0], path->slots[0]); + item_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]); + if (key.offset + item_size / csum_size * sectorsize <= bytenr) { + ret = 1; + goto out; + } + + final_offset = (bytenr - key.offset) / sectorsize * csum_size + + item_offset; + read_extent_buffer(path->nodes[0], csum_ret, final_offset, csum_size); + ret = 0; +out: + btrfs_free_path(path); + return ret; +}; diff --git a/ctree.h b/ctree.h index dd02ef86..506b107e 100644 --- a/ctree.h +++ b/ctree.h @@ -2798,4 +2798,7 @@ int btrfs_get_extent(struct btrfs_trans_handle *trans, int btrfs_punch_hole(struct btrfs_trans_handle *trans, struct btrfs_root *root, u64 ino, u64 offset, u64 len); +/* csum.c */ +int btrfs_read_one_data_csum(struct btrfs_fs_info *fs_info, u64 bytenr, + void *csum_ret); #endif -- 2.11.0 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
