From: Christoph Hellwig <hch@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH] xfs: reset buffer pointers before freeing them
Date: Mon, 11 Apr 2011 20:09:39 -0400 [thread overview]
Message-ID: <20110412000939.GC29358@infradead.org> (raw)
In-Reply-To: <1302491405-2290-1-git-send-email-david@fromorbit.com>
> error = xlog_bread_noalign(log, ealign, sectbb, bp);
> - if (error)
> - break;
>
> - error = XFS_BUF_SET_PTR(bp, offset, bufblks);
> + /* must reset buffer pointer even on error */
> + error2 = XFS_BUF_SET_PTR(bp, offset, bufblks);
This seems to be incorrect both in the original and your version.
>From all that I can see XFS_BUF_SET_PTR wants a byte count while bufblks
is a sector count, e.g. this should be:
error2 = XFS_BUF_SET_PTR(bp, offset, BBTOB(bufblks);
While at I think this mess with the buffer virtual mapping, read into it
and set it back mess needs to go into a single helper instead of beeing
duplicated three times. By having named arguments with proper types
bugs like the existing one above should also be much more obvious to
spot.
As a follow on patch to that I think we could also get rid of all the
vmap manipultions entirely, and just specify and I/O offset and length
manually. The only thing required for that is a number of pages
to skip at the beggining of the buffer from the log recovery code to
_xfs_buf_ioapply, either by passing it down procedurally, or by adding
a new filed to struct xfs_buf. In fact just relaxing the b_offset
semantics to allow offsets larger than a page only in the I/O path would
do it, but I'm not sure that version helps long-term maintenance.
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next prev parent reply other threads:[~2011-04-12 0:06 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-11 3:10 [PATCH] xfs: reset buffer pointers before freeing them Dave Chinner
2011-04-12 0:09 ` Christoph Hellwig [this message]
2011-04-12 11:00 ` Dave Chinner
2011-04-12 13:45 ` Dave Chinner
2011-04-12 16:22 ` Christoph Hellwig
2011-04-12 22:50 ` Dave Chinner
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