Neil Brown wrote:
On Sunday July 17, mjt@xxxxxxxxxx wrote:
[]
Note chunk size is never used on linear array. The
only usage of chunk_size member is in /proc/mdstat,
as "rounding" parameter (linear.c) - looks like it
should be removed too.
This statement isn't entirely true, though it took me a little while
to remind myself exactly how linear.c does use chunk_size.
linear_run in linear.c uses rdev->size for each devices.
in md.c rdev->size is set by a call to calc_dev_size()
calc_dev_size *does* use chunk_size (if it is non-zero)
Aha.
Well, in that case, the whole stuff around that check should
be reviewed. At least, all the various raid levels should
have device size to be at least PAGE_SIZE (as checked in the
code fragment surrounded by this if() statement).
BTW, I don't really know how we got zero chunksize in the
superblock in the first place. It was evms who screwed up
3-components linear array somehow (which worked before),
and, since I for one know nothing about evms, we tried to
assemble it with mdadm, which failed due to this very check
in kernel. So we were forced to re-create the array to
work around this in-kernel check (since for linear array
recreate operation is safe and leaves the data intact).
So maybe the whole issue is moot: how often do you see
an array with zero chunk-size?
Thanks.
/mjt
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