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https://github.com/kdave/btrfs-progs
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Add btrfs-map-logical program to map and read logical block numbers
This allows us to figure out which physical byte offset on which device is the real location for a given logical block number. It can optionally read the block in and save it to a file for debugging analysis. Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Chris Mason
parent
6f3cf25a4e
commit
ab8fb4c995
6
Makefile
6
Makefile
@ -16,7 +16,8 @@ prefix ?= /usr/local
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bindir = $(prefix)/bin
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LIBS=-luuid
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progs = btrfsctl mkfs.btrfs btrfs-debug-tree btrfs-show btrfs-vol btrfsck
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progs = btrfsctl mkfs.btrfs btrfs-debug-tree btrfs-show btrfs-vol btrfsck \
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btrfs-map-logical
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# make C=1 to enable sparse
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ifdef C
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@ -56,6 +57,9 @@ btrfs-debug-tree: $(objects) debug-tree.o
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btrfstune: $(objects) btrfstune.o
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gcc $(CFLAGS) -o btrfstune $(objects) btrfstune.o $(LDFLAGS) $(LIBS)
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btrfs-map-logical: $(objects) btrfs-map-logical.o
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gcc $(CFLAGS) -o btrfs-map-logical $(objects) btrfs-map-logical.o $(LDFLAGS) $(LIBS)
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btrfs-image: $(objects) btrfs-image.o
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gcc $(CFLAGS) -o btrfs-image $(objects) btrfs-image.o -lpthread -lz $(LDFLAGS) $(LIBS)
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221
btrfs-map-logical.c
Normal file
221
btrfs-map-logical.c
Normal file
@ -0,0 +1,221 @@
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/*
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* Copyright (C) 2009 Oracle. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#define _XOPEN_SOURCE 500
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#define _GNU_SOURCE 1
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#include <stdio.h>
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#include <stdlib.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <getopt.h>
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#include "kerncompat.h"
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#include "ctree.h"
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#include "volumes.h"
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#include "disk-io.h"
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#include "print-tree.h"
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#include "transaction.h"
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#include "list.h"
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#include "version.h"
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/* we write the mirror info to stdout unless they are dumping the data
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* to stdout
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* */
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static FILE *info_file;
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struct extent_buffer *debug_read_block(struct btrfs_root *root, u64 bytenr,
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u32 blocksize, int copy)
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{
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int ret;
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int dev_nr;
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struct extent_buffer *eb;
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u64 length;
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struct btrfs_multi_bio *multi = NULL;
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struct btrfs_device *device;
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int num_copies;
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int mirror_num = 1;
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eb = btrfs_find_create_tree_block(root, bytenr, blocksize);
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if (!eb)
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return NULL;
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dev_nr = 0;
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length = blocksize;
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while (1) {
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ret = btrfs_map_block(&root->fs_info->mapping_tree, READ,
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eb->start, &length, &multi, mirror_num);
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BUG_ON(ret);
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device = multi->stripes[0].dev;
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eb->fd = device->fd;
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device->total_ios++;
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eb->dev_bytenr = multi->stripes[0].physical;
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fprintf(info_file, "mirror %d logical %Lu physical %Lu "
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"device %s\n", mirror_num, bytenr, eb->dev_bytenr,
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device->name);
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kfree(multi);
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if (!copy || mirror_num == copy)
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ret = read_extent_from_disk(eb);
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num_copies = btrfs_num_copies(&root->fs_info->mapping_tree,
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eb->start, eb->len);
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if (num_copies == 1)
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break;
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mirror_num++;
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if (mirror_num > num_copies)
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break;
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}
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return eb;
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}
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static void print_usage(void)
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{
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fprintf(stderr, "usage: btrfs-map-logical [options] mount_point\n");
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fprintf(stderr, "\t-l Logical extent to map\n");
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fprintf(stderr, "\t-c Copy of the extent to read (usually 1 or 2)\n");
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fprintf(stderr, "\t-o Output file to hold the extent\n");
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fprintf(stderr, "\t-s Number of bytes to read\n");
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exit(1);
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}
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static struct option long_options[] = {
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/* { "byte-count", 1, NULL, 'b' }, */
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{ "logical", 1, NULL, 'l' },
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{ "copy", 1, NULL, 'c' },
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{ "output", 1, NULL, 'c' },
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{ "bytes", 1, NULL, 'b' },
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{ 0, 0, 0, 0}
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};
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int main(int ac, char **av)
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{
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struct cache_tree root_cache;
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struct btrfs_root *root;
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struct extent_buffer *eb;
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char *dev;
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char *output_file = NULL;
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u64 logical = 0;
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int ret = 0;
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int option_index = 0;
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int copy = 0;
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u64 bytes = 0;
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int out_fd = 0;
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int err;
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while(1) {
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int c;
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c = getopt_long(ac, av, "l:c:o:b:", long_options,
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&option_index);
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if (c < 0)
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break;
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switch(c) {
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case 'l':
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logical = atoll(optarg);
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if (logical == 0) {
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fprintf(stderr,
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"invalid extent number\n");
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print_usage();
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}
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break;
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case 'c':
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copy = atoi(optarg);
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if (copy == 0) {
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fprintf(stderr,
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"invalid copy number\n");
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print_usage();
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}
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break;
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case 'b':
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bytes = atoll(optarg);
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if (bytes == 0) {
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fprintf(stderr,
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"invalid byte count\n");
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print_usage();
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}
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break;
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case 'o':
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output_file = strdup(optarg);
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break;
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default:
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print_usage();
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}
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}
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ac = ac - optind;
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if (ac == 0)
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print_usage();
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if (logical == 0)
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print_usage();
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if (copy < 0)
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print_usage();
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dev = av[optind];
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radix_tree_init();
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cache_tree_init(&root_cache);
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root = open_ctree(dev, 0, 0);
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if (!root) {
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fprintf(stderr, "Open ctree failed\n");
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exit(1);
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}
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if (output_file) {
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if (strcmp(output_file, "-") == 0) {
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out_fd = 1;
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info_file = stderr;
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} else {
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out_fd = open(output_file, O_RDWR | O_CREAT, 0600);
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if (out_fd < 0)
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goto close;
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err = ftruncate(out_fd, 0);
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if (err) {
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close(out_fd);
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goto close;
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}
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info_file = stdout;
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}
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}
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if (bytes == 0)
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bytes = root->sectorsize;
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bytes = (bytes + root->sectorsize - 1) / root->sectorsize;
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bytes *= root->sectorsize;
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while (bytes > 0) {
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eb = debug_read_block(root, logical, root->sectorsize, copy);
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if (eb && output_file) {
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err = write(out_fd, eb->data, eb->len);
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if (err < 0 || err != eb->len) {
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fprintf(stderr, "output file write failed\n");
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goto out_close_fd;
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}
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}
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free_extent_buffer(eb);
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logical += root->sectorsize;
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bytes -= root->sectorsize;
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}
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out_close_fd:
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if (output_file && out_fd != 1)
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close(out_fd);
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close:
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close_ctree(root);
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return ret;
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}
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