On Thu, Dec 14, 2017 at 06:07:31PM -0800, Darrick J. Wong wrote:
<snip>
> +void
> +clonerange_f(
> + int opno,
> + long r)
> +{
<snip>
> + /* Calculate offsets */
> + len = (random() % FILELEN_MAX) + 1;
> + len &= ~(stat1.st_blksize - 1);
> + if (len == 0)
> + len = stat1.st_blksize;
> + if (len > stat1.st_size)
> + len = stat1.st_size;
> +
> + lr = ((__int64_t)random() << 32) + random();
> + if (stat1.st_size == len)
> + off1 = 0;
> + else
> + off1 = (off64_t)(lr % MIN(stat1.st_size - len, MAXFSIZE));
> + off1 %= maxfsize;
> + off1 &= ~(stat1.st_blksize - 1);
> +
> + /*
> + * If srcfile == destfile, randomly generate destination ranges
> + * until we find one that doesn't overlap the source range.
> + */
> + do {
> + lr = ((__int64_t)random() << 32) + random();
> + off2 = (off64_t)(lr % MIN(stat2.st_size + (1024 * 1024), MAXFSIZE));
> + off2 %= maxfsize;
> + off2 &= ~(stat2.st_blksize - 1);
> + } while (stat1.st_ino == stat2.st_ino && llabs(off2 - off1) < len);
I started seeing hangs in generic/013 on cephfs. After spending some
time looking, I found that this loops forever. And the reason seems to
be that stat1.st_blksize is too big for this filesystem (4M) -- when
doing:
off1 &= ~(stat1.st_blksize - 1);
off1 (and off2) will both end up with 0. Does this make sense? Would
something like:
- off1 &= ~(stat1.st_blksize - 1);
+ if (stat1.st_blksize <= stat1.st_size)
+ off1 &= ~(stat1.st_blksize - 1);
be acceptable? (and a similar change for off2, of course.)
Cheers,
--
Luís
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