Dave,
On 08/26/2015 04:37 PM, Dave Chinner wrote:
On Wed, Aug 26, 2015 at 12:36:42PM -0500, rjohnston@xxxxxxx wrote:
The call to memset will segfault because the offset for the first
parameter is done twice. We are using pointer math to do the
calculation.
The first time is when calculating oldsize, the size of i2gseg_t
is accounted for.
oldsize = (numsegs - SEGPERHNK) * sizeof(i2gseg_t);
Then in the call to memset, oldsize is again multiplied by the size
of i2gmap_t.
memset(inomap.i2gmap + oldsize, ...)
i2gmap holds the used inodes in each chunk. When there are 2^31 chunk
entries, it could describe 2^31 (1 inode/chunk)- 2^40 (64 inodes/chunk).
With 100s of millions of inodes there are enough entries to wrap the
32 bit variable oldsize.
Switching to use array index notation instead of calculating the
pointer address twice ;) would resolve this issue. The unneeded
local variable oldsize can be removed as well.
Per your other comment I will add a bounds check after calculating numsegs:
if (numsegs < 0)
return -1;
The description above will change to:
Adding a bounds check (numsegs < 0) and switching to use array
index notation instead of calculating the pointer address twice ;)
would resolve this issue. The unneeded local variable oldsize
can be removed as well.
numsegs is used to calculate an array index, change it from a
signed int (intgen_t) to an unsigned (uint32_t).
I will remove the above description and leave it as is (intgen_t)
Description does not match code:
- intgen_t numsegs;
- intgen_t oldsize;
+ int32_t numsegs;
It's still a signed int here. And, really, just a plain old "int" is
fine here.
Cheers,
Dave.
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