Eric Sandeen
2014-May-14 02:03 UTC
[PATCH] btrfs-show-super: don't try to print not-superblocks
If we point btrfs-show-super at a not-btrfs-device and
try to print all superblocks, bad things are apt to happen:
superblock: bytenr=274877906944, device=/dev/sdc2
---------------------------------------------------------
btrfs-show-super: ctree.h:1984: btrfs_super_csum_size: Assertion `!(t >=
(sizeof(btrfs_csum_sizes) / sizeof((btrfs_csum_sizes)[0])))' failed.
csum 0xAborted
Don't try to print superblocks that don't look like superblocks,
and add an "-f" (force) option to try anyway, if the user
really wants to give it a shot.
Fix some spelling & capitalization while we're at it.
The manpage says that if any problem happens, 1 will
be returned, but that's already not true today LOL, so
I didn't bother to make it true when we detect bad
sb magic, either...
I figure it's worth continuing and trying all superblocks
in case just one has a corrupt magic.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---
diff --git a/btrfs-show-super.c b/btrfs-show-super.c
index d4df0ac..023f099 100644
--- a/btrfs-show-super.c
+++ b/btrfs-show-super.c
@@ -40,16 +40,17 @@
static void print_usage(void);
static void dump_superblock(struct btrfs_super_block *sb);
int main(int argc, char **argv);
-static int load_and_dump_sb(char *, int fd, u64 sb_bytenr);
+static int load_and_dump_sb(char *, int fd, u64 sb_bytenr, int force);
static void print_usage(void)
{
fprintf(stderr,
- "usage: btrfs-show-super [-i super_mirror|-a] dev [dev..]\n");
+ "usage: btrfs-show-super [-i super_mirror|-a] [-f] dev [dev..]\n");
fprintf(stderr, "\tThe super_mirror number is between 0 and %d.\n",
BTRFS_SUPER_MIRROR_MAX - 1);
- fprintf(stderr, "\tIf -a is passed all the superblocks are
showed.\n");
+ fprintf(stderr, "\tIf -a is passed all the superblocks are
shown.\n");
+ fprintf(stderr, "\tPass -f to attempt to dump superblocks with bad
magic.\n");
fprintf(stderr, "%s\n", BTRFS_BUILD_VERSION);
}
@@ -60,10 +61,11 @@ int main(int argc, char **argv)
char *filename;
int fd = -1;
int i;
+ int force = 0;
u64 arg;
u64 sb_bytenr = btrfs_sb_offset(0);
- while ((opt = getopt(argc, argv, "ai:")) != -1) {
+ while ((opt = getopt(argc, argv, "afi:")) != -1) {
switch (opt) {
case 'i':
arg = arg_strtou64(optarg);
@@ -81,6 +83,10 @@ int main(int argc, char **argv)
all = 1;
break;
+ case 'f':
+ force = 1;
+ break;
+
default:
print_usage();
exit(1);
@@ -104,7 +110,8 @@ int main(int argc, char **argv)
int idx;
for (idx = 0; idx < BTRFS_SUPER_MIRROR_MAX; idx++) {
sb_bytenr = btrfs_sb_offset(idx);
- if (load_and_dump_sb(filename, fd, sb_bytenr)) {
+ if (load_and_dump_sb(filename, fd,
+ sb_bytenr, force)) {
close(fd);
exit(1);
}
@@ -112,7 +119,7 @@ int main(int argc, char **argv)
putchar('\n');
}
} else {
- load_and_dump_sb(filename, fd, sb_bytenr);
+ load_and_dump_sb(filename, fd, sb_bytenr, force);
putchar('\n');
}
close(fd);
@@ -121,7 +128,7 @@ int main(int argc, char **argv)
exit(0);
}
-static int load_and_dump_sb(char *filename, int fd, u64 sb_bytenr)
+static int load_and_dump_sb(char *filename, int fd, u64 sb_bytenr, int force)
{
u8 super_block_data[BTRFS_SUPER_INFO_SIZE];
struct btrfs_super_block *sb;
@@ -146,7 +153,12 @@ static int load_and_dump_sb(char *filename, int fd, u64
sb_bytenr)
}
printf("superblock: bytenr=%llu, device=%s\n", sb_bytenr, filename);
printf("---------------------------------------------------------\n");
- dump_superblock(sb);
+ if (btrfs_super_magic(sb) != BTRFS_MAGIC && !force) {
+ fprintf(stderr,
+ "ERROR: bad magic on superblock on %s at %llu\n",
+ filename, (unsigned long long)sb_bytenr);
+ } else
+ dump_superblock(sb);
return 0;
}
diff --git a/man/btrfs-show-super.8.in b/man/btrfs-show-super.8.in
index 3fe8bde..582649a 100644
--- a/man/btrfs-show-super.8.in
+++ b/man/btrfs-show-super.8.in
@@ -10,9 +10,11 @@ first superblock will be printed out.
\fIOptions\fP
.IP "\fB-a\fP" 5
-print all the superblock information, if this option is given,
'\fB-i\fP' option will be ignored.
+Print all the superblock information, if this option is given,
'\fB-i\fP' option will be ignored.
+.IP "\fB-f\fP" 5
+Attempt to print the superblock even if no superblock magic is found. May end
badly.
.IP "\fB-i \fI<super_mirror>\fP" 5
-specify which mirror to print out. \fI<super_mirror>\fP is between 0 and
2. if several '\fB-i \fI<super_mirror>\fP'\fR are given, only the
last one is valid.
+Specify which mirror to print out. \fI<super_mirror>\fP is between 0 and
2. If several '\fB-i \fI<super_mirror>\fP'\fR are given, only the
last one is valid.
.SH EXIT CODE
\fBbtrfs-show-super\fR will return 0 exit code if no error happened.
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