e2image: add -n option to show what blocks would have been written

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/misc/e2image.8.in b/misc/e2image.8.in
index cdf63bf..71ada46 100644 (file)
--- a/misc/e2image.8.in
+++ b/misc/e2image.8.in
@@ -8,7 +8,7 @@ e2image \- Save critical ext2/ext3/ext4 filesystem metadata to a file
 .SH SYNOPSIS
 .B e2image
 [
-.B \-acfprsIQ
+.B \-acfnprsIQ
 ]
 [
 .B \-o
@@ -218,7 +218,10 @@ option which cause e2image to try reading a block from the destination
 to see if it is identical to the block which
 .B e2image
 is about to copy.  If the block is already the same, the write can be
-skipped.
+skipped.  The
+.B \-n
+option will cause all of the writes to be no-ops, and print the blocks
+that would have been written.
 .PP
 .SH OFFSETS
 Normally a filesystem starts at the beginning of a partition, and

diff --git a/misc/e2image.c b/misc/e2image.c
index 7394df5..36c7265 100644 (file)
--- a/misc/e2image.c
+++ b/misc/e2image.c
@@ -49,6 +49,7 @@ extern int optind;
 #include "nls-enable.h"
 
 #define QCOW_OFLAG_COPIED     (1LL << 63)
+#define NO_BLK ((blk64_t) -1)
 
 /* Image types */
 #define E2IMAGE_RAW    1
@@ -64,6 +65,7 @@ static const char * program_name = "e2image";
 static char * device_name = NULL;
 static char all_data;
 static char output_is_blk;
+static char nop_flag;
 /* writing to blk device: don't skip zeroed blocks */
 static blk64_t source_offset, dest_offset;
 static char move_mode;
@@ -96,7 +98,7 @@ static int get_bits_from_size(size_t size)
 
 static void usage(void)
 {
-       fprintf(stderr, _("Usage: %s [-acfprsIQ] [-o src_offset] "
+       fprintf(stderr, _("Usage: %s [-acfnprsIQ] [-o src_offset] "
                          "[-O dest_offset] \\\n\tdevice image_file\n"),
                program_name);
        exit (1);
@@ -164,7 +166,11 @@ static void generic_write(int fd, void *buf, int blocksize, blk64_t block)
                        exit(1);
                }
        }
-
+       if (nop_flag) {
+               printf("Writing block %llu\n", (unsigned long long) block);
+               seek_relative(fd, blocksize);
+               return;
+       }
        count = write(fd, buf, blocksize);
        if (count != blocksize) {
                if (count == -1)
@@ -207,7 +213,7 @@ static void write_header(int fd, void *hdr, int hdr_size, int wrt_size)
        if (hdr)
                memcpy(header_buf, hdr, hdr_size);
 
-       generic_write(fd, header_buf, wrt_size, 0);
+       generic_write(fd, header_buf, wrt_size, NO_BLK);
 
        ext2fs_free_mem(&header_buf);
 }
@@ -714,13 +720,13 @@ more_blocks:
 
                if (ftruncate64(fd, offset) < 0) {
                        seek_relative(fd, -1);
-                       generic_write(fd, zero_buf, 1, -1);
+                       generic_write(fd, zero_buf, 1, NO_BLK);
                }
        }
 #else
        if (sparse && !distance) {
                seek_relative(fd, sparse-1);
-               generic_write(fd, zero_buf, 1, -1);
+               generic_write(fd, zero_buf, 1, NO_BLK);
        }
 #endif
        ext2fs_free_mem(&zero_buf);
@@ -985,7 +991,8 @@ static void flush_l2_cache(struct ext2_qcow2_image *image)
                        seek = table->offset;
                }
 
-               generic_write(fd, (char *)table->data, image->cluster_size , 0);
+               generic_write(fd, (char *)table->data, image->cluster_size,
+                             NO_BLK);
                put_used_table(image, &table);
                seek += image->cluster_size;
        }
@@ -1071,7 +1078,7 @@ static int update_refcount(int fd, struct ext2_qcow2_image *img,
                seek_set(fd, ref->refcount_block_offset);
 
                generic_write(fd, (char *)ref->refcount_block,
-                             img->cluster_size, 0);
+                             img->cluster_size, NO_BLK);
                memset(ref->refcount_block, 0, img->cluster_size);
 
                ref->refcount_table[ref->refcount_table_index] =
@@ -1102,10 +1109,11 @@ static int sync_refcount(int fd, struct ext2_qcow2_image *img)
                ext2fs_cpu_to_be64(ref->refcount_block_offset);
        seek_set(fd, ref->refcount_table_offset);
        generic_write(fd, (char *)ref->refcount_table,
-               ref->refcount_table_clusters << img->cluster_bits, 0);
+               ref->refcount_table_clusters << img->cluster_bits, NO_BLK);
 
        seek_set(fd, ref->refcount_block_offset);
-       generic_write(fd, (char *)ref->refcount_block, img->cluster_size, 0);
+       generic_write(fd, (char *)ref->refcount_block, img->cluster_size,
+                     NO_BLK);
        return 0;
 }
 
@@ -1192,7 +1200,7 @@ static void output_qcow2_meta_data_blocks(ext2_filsys fs, int fd)
                                }
                        }
 
-                       generic_write(fd, buf, fs->blocksize, 0);
+                       generic_write(fd, buf, fs->blocksize, blk);
 
                        if (add_l2_item(img, blk, offset,
                                        offset + img->cluster_size)) {
@@ -1223,7 +1231,7 @@ static void output_qcow2_meta_data_blocks(ext2_filsys fs, int fd)
        /* Write l1_table*/
        seek_set(fd, img->l1_offset);
        size = img->l1_size * sizeof(__u64);
-       generic_write(fd, (char *)img->l1_table, size, 0);
+       generic_write(fd, (char *)img->l1_table, size, NO_BLK);
 
        ext2fs_free_mem(&buf);
        free_qcow2_image(img);
@@ -1446,7 +1454,7 @@ int main (int argc, char ** argv)
        if (argc && *argv)
                program_name = *argv;
        add_error_table(&et_ext2_error_table);
-       while ((c = getopt(argc, argv, "rsIQafo:O:pc")) != EOF)
+       while ((c = getopt(argc, argv, "nrsIQafo:O:pc")) != EOF)
                switch (c) {
                case 'I':
                        flags |= E2IMAGE_INSTALL_FLAG;
@@ -1470,6 +1478,9 @@ int main (int argc, char ** argv)
                case 'f':
                        ignore_rw_mount = 1;
                        break;
+               case 'n':
+                       nop_flag = 1;
+                       break;
                case 'o':
                        source_offset = strtoull(optarg, NULL, 0);
                        break;