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From: Jan Kara <jack@suse.cz>
To: xfs@oss.sgi.com
Cc: Jan Kara <jack@suse.cz>
Subject: [PATCH] xfs: Fix rounding in xfs_alloc_fix_len()
Date: Wed,  4 Jun 2014 11:48:13 +0200	[thread overview]
Message-ID: <1401875293-16227-1-git-send-email-jack@suse.cz> (raw)

Rounding in xfs_alloc_fix_len() is wrong. As the comment states, the
result should be a number of a form (k*prod+mod) however due to sign
mistake the result is different. As a result allocations on raid arrays
could be misaligned in some cases.

This also seems to fix occasional assertion failure:
	XFS_WANT_CORRUPTED_GOTO(rlen <= flen, error0)
in xfs_alloc_ag_vextent_size().

Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/xfs/xfs_alloc.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/fs/xfs/xfs_alloc.c b/fs/xfs/xfs_alloc.c
index c1cf6a336a72..6a0281b16451 100644
--- a/fs/xfs/xfs_alloc.c
+++ b/fs/xfs/xfs_alloc.c
@@ -257,14 +257,12 @@ xfs_alloc_fix_len(
 	k = rlen % args->prod;
 	if (k == args->mod)
 		return;
-	if (k > args->mod) {
-		if ((int)(rlen = rlen - k - args->mod) < (int)args->minlen)
-			return;
-	} else {
-		if ((int)(rlen = rlen - args->prod - (args->mod - k)) <
-		    (int)args->minlen)
-			return;
-	}
+	if (k > args->mod)
+		rlen = rlen - (k - args->mod);
+	else
+		rlen = rlen - args->prod + (args->mod - k);
+	if ((int)rlen < (int)args->minlen)
+		return;
 	ASSERT(rlen >= args->minlen);
 	ASSERT(rlen <= args->maxlen);
 	args->len = rlen;
-- 
1.8.1.4

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             reply	other threads:[~2014-06-04  9:48 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-06-04  9:48 Jan Kara [this message]
2014-06-04 13:35 ` [PATCH] xfs: Fix rounding in xfs_alloc_fix_len() Brian Foster
2014-06-04 15:10   ` Jan Kara
2014-06-04 15:54     ` Brian Foster

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