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From: Eric Sandeen <sandeen@redhat.com>
To: xfs-oss <xfs@oss.sgi.com>
Subject: [PATCH] xfs: remove pointless pointer increment in xfs_dir2_block_compact()
Date: Wed, 09 Apr 2014 15:30:49 -0500	[thread overview]
Message-ID: <5345ADF9.2030402@redhat.com> (raw)

xfs_dir2_block_compact() is passed a pointer to *blp, and
advances it locally - but nobody uses the pointer (locally)
after that.

This behavior came about as part of prior refactoring,

20f7e9f xfs: factor dir2 block read operations

and looking at the code as it was before, it seems quite clear
that this change introduced a bug; the pre-refactoring code
expects blp to be modified after compaction.
And indeed it did; see this commit which fixed it:

37f1356 xfs: recalculate leaf entry pointer after compacting a dir2 block

So the bug was introduced & resolved in the 3.8 cycle.

Whoops.  Well, it's fixed now, and mystery solved; just remove
the now-pointless local increment of the blp pointer.

(I guess we should have run clang earlier!)

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---

diff --git a/fs/xfs/xfs_dir2_block.c b/fs/xfs/xfs_dir2_block.c
index 4f6a38c..5259939 100644
--- a/fs/xfs/xfs_dir2_block.c
+++ b/fs/xfs/xfs_dir2_block.c
@@ -319,7 +319,6 @@ xfs_dir2_block_compact(
 		(xfs_dir2_data_aoff_t)((char *)blp - (char *)hdr),
 		(xfs_dir2_data_aoff_t)((be32_to_cpu(btp->stale) - 1) * sizeof(*blp)),
 		needlog, &needscan);
-	blp += be32_to_cpu(btp->stale) - 1;
 	btp->stale = cpu_to_be32(1);
 	/*
 	 * If we now need to rebuild the bestfree map, do so.

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             reply	other threads:[~2014-04-09 20:30 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-04-09 20:30 Eric Sandeen [this message]
2014-04-09 21:34 ` [PATCH] xfs: remove pointless pointer increment in xfs_dir2_block_compact() Mark Tinguely
2014-04-09 21:35   ` Eric Sandeen

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