commit 263b53767a3df33f392262f539bfb35ec578f5e5
Author: Eric Sandeen <sandeen@redhat.com>
Date: Thu Nov 13 10:02:22 2014 +1100
xfs_copy: simplify first_agbno calculation
After ffe9a9a xfsprogs: xfs_copy: fix data corruption of target,
xfs_copy started hitting an ASSERT for a 4k sector / 4k blocksize
filesystem:
# dd if=/dev/zero of=test.img bs=1M count=1024
# mkfs.xfs -s size=4096 test.img
# xfs_copy test.img xfs.img
xfs_copy: xfs_copy.c:720: main: Assertion `((((((xfs_daddr_t)(3 << (mp)->m_sectbb_log)) + 1) * (1<<9)) + first_residue) % source_blocksize) == 0' failed.
Aborted
I started digging through all the calculations below, and realized
that in the end, all it wants is the first filesystem block after
the AG header. XFS_AGFL_BLOCK(mp) + 1 suffices for this purpose;
rip out the rest which seems overly complex and apparently bug-prone.
I tested this by creating a 4g filesystem with combinations of
sector & block size between 512 and 4k, copying in /lib/modules,
running an xfs_copy of that, and running repair against the copy;
it all looks good. It took a long time, but I will create a
simpler/shorter xfstest based on this.
Reported-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
diff --git a/copy/xfs_copy.c b/copy/xfs_copy.c
index 7ce5ec9..279527c 100644
--- a/copy/xfs_copy.c
+++ b/copy/xfs_copy.c
@@ -475,7 +475,7 @@ main(int argc, char **argv)
int open_flags;
xfs_off_t pos, end_pos;
size_t length;
- int c, first_residue, tmp_residue;
+ int c;
__uint64_t size, sizeb;
__uint64_t numblocks = 0;
int wblocks = 0;
@@ -697,27 +697,13 @@ main(int argc, char **argv)
ASSERT(source_blocksize % source_sectorsize == 0);
ASSERT(source_sectorsize % BBSIZE == 0);
- if (source_blocksize > source_sectorsize) {
- /* get number of leftover sectors in last block of ag header */
-
- tmp_residue = ((XFS_AGFL_DADDR(mp) + 1) * BBSIZE)
- % source_blocksize;
- first_residue = (tmp_residue == 0) ? 0 :
- source_blocksize - tmp_residue;
- ASSERT(first_residue % source_sectorsize == 0);
- } else if (source_blocksize == source_sectorsize) {
- first_residue = 0;
- } else {
+ if (source_blocksize < source_sectorsize) {
do_log(_("Error: filesystem block size is smaller than the"
" disk sectorsize.\nAborting XFS copy now.\n"));
exit(1);
}
- first_agbno = (((XFS_AGFL_DADDR(mp) + 1) * BBSIZE)
- + first_residue) / source_blocksize;
- ASSERT(first_agbno != 0);
- ASSERT(((((XFS_AGFL_DADDR(mp) + 1) * BBSIZE)
- + first_residue) % source_blocksize) == 0);
+ first_agbno = XFS_AGFL_BLOCK(mp) + 1;
/* now open targets */