Hi Stefan,
On 2012-10-19 09:18, Stefan Behrens wrote:
> Just a small program to print the fields of a super block.
>
> Signed-off-by: Stefan Behrens <sbehrens@xxxxxxxxxxxxxxxx>
> ---
[...]
> +
> +
> +static void print_usage(void)
> +{
> + fprintf(stderr, "usage: btrfs-show-super [-i super_mirror] dev\n");
> + fprintf(stderr, "\tThe super_mirror number is between 0 and %d.\n",
> + BTRFS_SUPER_MIRROR_MAX - 1);
What about adding a flag '-a' to show all the superblocks ?
> + fprintf(stderr, "%s\n", BTRFS_BUILD_VERSION);
> +}
> +
[...]
> +static void dump_superblock(struct btrfs_super_block *sb)
> +{
> + printf("bytenr\t%llu\n", (unsigned long long)btrfs_super_bytenr(sb));
> + printf("flags\t0x%llx\n", (unsigned long long)btrfs_super_flags(sb));
> + printf("magic \t0x%llx (little endian)\n",
> + (unsigned long long)sb->magic);
I suggest to print if magic matches or not. The same if csum matches or
not. This help to understand if the superblock is valid or not.
> + btrfs_print_id("fsid\t", sb->fsid, BTRFS_FSID_SIZE);
Please, use the uuid_unparse() function, so the output is like the other
btrfs tools. Be aware that the libuuid is already linked.
> + btrfs_print_id("label\t", (u8 *)sb->label, BTRFS_LABEL_SIZE);
Does make sense to output the label as hex digits ? I prefer the ascii
value, in order to avoid garbage I suggest something like:
#include <ctype.h>
char *p;
for( p= sb->label ; *p ; p++ ) putchar(isprint(*p) ? *p : '_' );
> + printf("generation\t%llu\n",
> + (unsigned long long)btrfs_super_generation(sb));
> + printf("root\t%llu\n", (unsigned long long)btrfs_super_root(sb));
> + printf("sys_array_size\t%llu\n",
> + (unsigned long long)btrfs_super_sys_array_size(sb));
[...]
> + printf("dev_item.generation\t%llu\n", (unsigned long long)
> + btrfs_stack_device_generation(&sb->dev_item));
Could you please add also the sb->dev_item.uuid and sb->dev_item.fsid
fields ?
Moreover I suggest to align every value to the right. For example a my
test shows:
bytenr 65536
flags 0x1
magic 0x4d5f53665248425f (little endian)
fsid 1A:FD:C9:5D:3C:27:43:90:A2:C8:7A:F6:87:C8:82:B1
label
00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00
generation 4
root 4214784
sys_array_size 97
chunk_root_generation 2
root_level 0
chunk_root 139264
chunk_root_level 0
log_root 0
log_root_transid 0
log_root_level 0
total_bytes 1073741824
[...]
I think that it could be more readable as
bytenr 65536
flags 0x1
magic 0x4d5f53665248425f (little endian)
generation 4
root 4214784
sys_array_size 97
chunk_root_generation 2
root_level 0
chunk_root 139264
chunk_root_level 0
log_root 0
log_root_transid 0
log_root_level 0
total_bytes 1073741824
In order to avoid to check every space, I suggest to change every printf
from
> + printf("dev_item.type\t%llu\n", (unsigned long long)
> + btrfs_stack_device_type(&sb->dev_item));
to
printf("%-50s%20llu\n",
"dev_item.type",
(unsigned long long)btrfs_stack_device_type(&sb->dev_item));
BR
G.Baroncelli
--
gpg @keyserver.linux.it: Goffredo Baroncelli (kreijackATinwind.it>
Key fingerprint BBF5 1610 0B64 DAC6 5F7D 17B2 0EDA 9B37 8B82 E0B5
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