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The linux bitset operators (test_bit, set_bit etc) work on arrays of "unsigned
long". dm-log uses such bitsets but treats them as arrays of uint32_t, only
allocating and zeroing a multiple of 4 bytes (as 'clean_bits' is a uint32_t).
The patch below fixes this problem.
The problem is specific to 64-bit big endian machines such as s390x or ppc-64
and can prevent pvmove terminating.
In the simplest case, if "region_count" were (say) 30, then
bitset_size (below) would be 4 and bitset_uint32_count would be 1.
Thus the memory for this butset, after allocation and zeroing would
be
0 0 0 0 X X X X
On a bigendian 64bit machine, bit 0 for this bitset is in the 8th
byte! (and every bit that dm-log would use would be in the X area).
0 0 0 0 X X X X
^
here
which hasn't been cleared properly.
As the dm-raid1 code only syncs and counts regions which have a 0 in the
'sync_bits' bitset, and only finishes when it has counted high enough, a large
number of 1's among those 'X's will cause the sync to not complete.
It is worth noting that the code uses the same bitsets for in-memory and
on-disk logs. As these bitsets are host-endian and host-sized, this means
that they cannot safely be moved between computers with
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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|---|---|---|
| .. | ||
| raid6test | ||
| bitmap.c | ||
| dm-bio-list.h | ||
| dm-bio-record.h | ||
| dm-crypt.c | ||
| dm-emc.c | ||
| dm-exception-store.c | ||
| dm-hw-handler.c | ||
| dm-hw-handler.h | ||
| dm-io.c | ||
| dm-io.h | ||
| dm-ioctl.c | ||
| dm-linear.c | ||
| dm-log.c | ||
| dm-log.h | ||
| dm-mpath.c | ||
| dm-mpath.h | ||
| dm-path-selector.c | ||
| dm-path-selector.h | ||
| dm-raid1.c | ||
| dm-round-robin.c | ||
| dm-snap.c | ||
| dm-snap.h | ||
| dm-stripe.c | ||
| dm-table.c | ||
| dm-target.c | ||
| dm-zero.c | ||
| dm.c | ||
| dm.h | ||
| faulty.c | ||
| Kconfig | ||
| kcopyd.c | ||
| kcopyd.h | ||
| linear.c | ||
| Makefile | ||
| md.c | ||
| mktables.c | ||
| multipath.c | ||
| raid0.c | ||
| raid1.c | ||
| raid5.c | ||
| raid6.h | ||
| raid6algos.c | ||
| raid6altivec.uc | ||
| raid6int.uc | ||
| raid6main.c | ||
| raid6mmx.c | ||
| raid6recov.c | ||
| raid6sse1.c | ||
| raid6sse2.c | ||
| raid6x86.h | ||
| raid10.c | ||
| unroll.pl | ||
| xor.c | ||