Hi,
I emailed this a few weeks ago, but now took a little more
of an aggresive attack on the problem and found that from what I
can tell BMV_OF_PREALLOC is never set from the linux/fs/xfs kernel
calls. Indeed a
xfs]$ find . -type f -exec grep BMV_OF_PREALLOC {} \;
fails to see anything in the kernel code using that value.
in /usr/include/xfs_fs.h #line:133
/* bmv_oflags values - returned for for each non-header segment */
#define BMV_OF_PREALLOC 0x1 /* segment = unwritten pre-allocation */
and I had monstered my private xfs_bmap to output the
printf(" bmv_oflags=\"%lld\" ", map[i+1].bmv_oflags);
which are always == 0;
It seems that from line 5759 in fs/xfs/xfs_bmap.c
if ( prealloced
&& map[i].br_startblock == HOLESTARTBLOCK
&& out.bmv_offset + out.bmv_length == bmvend) {
/*
* came to hole at end of file
*/
goto unlock_and_return;
} else {
that just before the goto maybe
if( interface & BMV_IF_PREALLOC )
bmv->bmv_oflags |= BMV_OF_PREALLOC;
though I have not looked very deeply at the code, it definately
seems to be a bug that the oflags are not being set.
--
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