在 2024/8/27 11:23, Dave Chinner 写道:
On Thu, Aug 22, 2024 at 05:49:12PM -0700, Darrick J. Wong wrote:
On Wed, Aug 21, 2024 at 06:44:12PM +0800, liuhuan01@xxxxxxxxxx wrote:
From: liuh <liuhuan01@xxxxxxxxxx>
Recently, I was testing xfstests. When I run xfs/350 case, it always generate coredump during the process.
xfs_db -c "sb 0" -c "p agblocks" /dev/loop1
System will generate signal SIGFPE corrupt the process. And the stack as follow:
corrupt at: (*bpp)->b_pag = xfs_perag_get(btp->bt_mount, xfs_daddr_to_agno(btp->bt_mount, blkno)); in function libxfs_getbuf_flags
#0 libxfs_getbuf_flags
#1 libxfs_getbuf_flags
#2 libxfs_buf_read_map
#3 libxfs_buf_read
#4 libxfs_mount
#5 init
#6 main
The coredump was caused by the corrupt superblock metadata: (mp)->m_sb.sb_agblocks, it was 0.
In this case, user cannot run in expert mode also.
Never check (mp)->m_sb.sb_agblocks before use it cause this issue.
Make sure (mp)->m_sb.sb_agblocks > 0 before libxfs_mount to prevent corruption and leave a message.
Signed-off-by: liuh <liuhuan01@xxxxxxxxxx>
---
db/init.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/db/init.c b/db/init.c
index cea25ae5..2d3295ba 100644
--- a/db/init.c
+++ b/db/init.c
@@ -129,6 +129,13 @@ init(
}
}
+ if (unlikely(sbp->sb_agblocks == 0)) {
+ fprintf(stderr,
+ _("%s: device %s agblocks unexpected\n"),
+ progname, x.data.name);
+ exit(1);
What if we set sb_agblocks to 1 and let the debugger continue?
Yeah, I'd prefer that xfs_db will operate on a corrupt filesystem and
maybe crash unexpectedly than to refuse to allow any diagnosis of
the corrupt filesystem.
xfs_db is a debug and forensic analysis tool. Having it crash
because it didn't handle some corruption entirely corectly isn't
something that we should be particularly worried about...
-Dave.
I agree with both of you, xfs_db is just a debugger tool.
But for the above case, xfs_db can do nothing, even do a simple view on
primary superblock.
The user all knowns is that xfs_db goto corrupt, but don't know what's
cause the problem.
If set sb_agblocks to 1, xfs_db can going to work to view on primary
superblock,
but can't relay on it to view more information.
Maybe left a warning message and set sb_agblocks to 1 and let debugger
continue is better.
Thanks.
