From: Peter Chubb <peter@chubb.wattle.id.au>
To: David Mansfield <lkml@dm.cobite.com>,
akpm@zip.com.au, torvalds@transmeta.com
Cc: linux-kernel@vger.kernel.org
Subject: [BUG] Compile failure (gcc 2.96 bug?). 2.5.42 raid0.c
Date: Tue, 15 Oct 2002 10:18:14 +1000 [thread overview]
Message-ID: <15787.24262.280423.570957@wombat.chubb.wattle.id.au> (raw)
In-Reply-To: <540557597@toto.iv>
>>>>> "David" == David Mansfield <lkml@dm.cobite.com> writes:
David> Trying to compile 2.5.42 I encountered the following error,
David> which looks a lot like a GCC bug. I did a 'make mrproper; make
David> oldconfig; make bzImage' and it still failed.
(lots of gcc internal structure dump deleted here)
Yes it's a GCC optimiser bug. I'm surprised I didn't see it: I tried
a whole heap of different compilers on that code, and had problems
only on the earlier similar code in raid0_run().
I didn't try redhat's compilers (I run debian) but didn't expect the
behaviour to be that different.
Anyway, please apply this patch (which also fixes the chunk overlap
problems).
diff -Nur --exclude=SCCS --exclude=BitKeeper --exclude=ChangeSet linux-2.5-import/drivers/md/raid0.c linux-2.5-mdfix/drivers/md/raid0.c
--- linux-2.5-import/drivers/md/raid0.c Mon Oct 14 10:32:35 2002
+++ linux-2.5-mdfix/drivers/md/raid0.c Tue Oct 15 10:03:07 2002
@@ -162,6 +162,29 @@
return 1;
}
+/**
+ * raid0_mergeable_bvec -- tell bio layer if a two requests can be merged
+ * @q: request queue
+ * @bio: the buffer head that's been built up so far
+ * @biovec: the request that could be merged to it.
+ *
+ * Return 1 if the merge is not permitted (because the
+ * result would cross a chunk boundary), 0 otherwise.
+ */
+static int raid0_mergeable_bvec(request_queue_t *q, struct bio *bio, struct bio_vec *biovec)
+{
+ mddev_t *mddev = q->queuedata;
+ sector_t block;
+ unsigned int chunk_size;
+ unsigned int bio_sz;
+
+ chunk_size = mddev->chunk_size >> 10;
+ block = bio->bi_sector >> 1;
+ bio_sz = (bio->bi_size + biovec->bv_len) >> 10;
+
+ return chunk_size < ((block & (chunk_size - 1)) + bio_sz);
+}
+
static int raid0_run (mddev_t *mddev)
{
unsigned cur=0, i=0, nb_zone;
@@ -233,6 +256,8 @@
conf->hash_table[i++].zone1 = conf->strip_zone + cur;
size -= (conf->smallest->size - zone0_size);
}
+ blk_queue_max_sectors(&mddev->queue, mddev->chunk_size >> 9);
+ blk_queue_merge_bvec(&mddev->queue, raid0_mergeable_bvec);
return 0;
out_free_zone_conf:
@@ -262,13 +287,6 @@
return 0;
}
-/*
- * FIXME - We assume some things here :
- * - requested buffers NEVER bigger than chunk size,
- * - requested buffers NEVER cross stripes limits.
- * Of course, those facts may not be valid anymore (and surely won't...)
- * Hey guys, there's some work out there ;-)
- */
static int raid0_make_request (request_queue_t *q, struct bio *bio)
{
mddev_t *mddev = q->queuedata;
@@ -286,13 +304,16 @@
{
+#if __GNUC__ < 3
+ volatile
+#endif
sector_t x = block;
sector_div(x, (unsigned long)conf->smallest->size);
hash = conf->hash_table + x;
}
- /* Sanity check */
- if (chunk_size < (block & (chunk_size - 1)) + (bio->bi_size >> 10))
+ /* Sanity check -- queue functions should prevent this happening */
+ if (unlikely(chunk_size < (block & (chunk_size - 1)) + (bio->bi_size >> 10)))
goto bad_map;
if (!hash)
next parent reply other threads:[~2002-10-15 0:13 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <540557597@toto.iv>
2002-10-15 0:18 ` Peter Chubb [this message]
2002-10-14 20:27 [BUG] Compile failure (gcc 2.96 bug?). 2.5.42 raid0.c David Mansfield
2002-10-14 20:54 ` Arjan van de Ven
2002-10-14 21:11 ` Arjan van de Ven
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=15787.24262.280423.570957@wombat.chubb.wattle.id.au \
--to=peter@chubb.wattle.id.au \
--cc=akpm@zip.com.au \
--cc=linux-kernel@vger.kernel.org \
--cc=lkml@dm.cobite.com \
--cc=torvalds@transmeta.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.