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Re: [PATCH v4] xfs: probe data buffer from page cache for unwritten exte

To: jeff.liu@xxxxxxxxxx
Subject: Re: [PATCH v4] xfs: probe data buffer from page cache for unwritten extents
From: Mark Tinguely <tinguely@xxxxxxx>
Date: Fri, 20 Jul 2012 13:46:30 -0500
Cc: xfs@xxxxxxxxxxx
In-reply-to: <50091696.4000903@xxxxxxxxxx>
References: <50091696.4000903@xxxxxxxxxx>
User-agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:9.0) Gecko/20120122 Thunderbird/9.0
On 07/20/12 03:28, Jeff Liu wrote:
Hi All,

According to Mark and Christoph's comments for v3, except optimizing 
xfs_seek_data() with unwritten extents
probing, the xfs_seek_hole() is also refined to that in this version.



Just some feedback.

Test program fragment:

        ret = do_fallocate(fd, 512*1024, 256*1024, 0);
        if (ret < 0)
                goto out;
        pwrite(fd, buf, 4096, 1024*516);
        lseek(fd, 800*1024, SEEK_SET);
        ret = write(fd, buf, bufsz);
        if (ret < 0)
                goto out;

Output:

HOLE/DATA at 512K 786432 / 528384   <- undiscovered hole here
HOLE/DATA at 516K 786432 / 528384   <- okay, data but we should
                                        return next page as hole.
HOLE/DATA at 520K 532480 / 819200   <- hole is discovered because
                                       there is no trailing data

--Mark.

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