Matteo Frigo <athena@xxxxxxxx> writes:
> Well, I don't really know anything about this topic, so I may be
> completely off the mark, but dm-raid1.c:mirror_map() does indeed return
> EWOULDBLOCK, and EWOULDBLOCK is #define'd to be EAGAIN, so it seems to
> me that dm-raid1 does indeed return EAGAIN for "rw == READA" (which I
> assume is read-ahead) if the "region is not in-sync":
>
> /*
> * If region is not in-sync queue the bio.
> */
> if (!r || (r == -EWOULDBLOCK)) {
> if (rw == READA)
> return -EWOULDBLOCK;
>
> queue_bio(ms, bio, rw);
> return DM_MAPIO_SUBMITTED;
> }
Dave (and others),
do you have any suggestion on what should be done to fix this bug?
I have tried returning -EIO instead of -EWOULDBLOCK, but xfs does not
like that. dm-zero.c:zero_map() appears to return -EIO too, so this is
another potential issue.
I have verified that removing the READA special case, treating READA
like READ, fixes the problem:
if(0) if (rw == READA)
return -EWOULDBLOCK;
Of course this "fix" throws away the baby with the bath water.
I am willing to write and submit a patch, but I would appreciate
directions as to what the correct protocol between xfs and dm is
supposed to be.
Regards,
MF
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