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Re: [PATCH] xfs: fix the wrong new_size/rnew_size at xfs_iext_realloc_di

To: Jeff Liu <jeff.liu@xxxxxxxxxx>
Subject: Re: [PATCH] xfs: fix the wrong new_size/rnew_size at xfs_iext_realloc_direct()
From: Ben Myers <bpm@xxxxxxx>
Date: Tue, 1 Oct 2013 17:33:40 -0500
Cc: "xfs@xxxxxxxxxxx" <xfs@xxxxxxxxxxx>
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <523EA96B.3040904@xxxxxxxxxx>
References: <523EA96B.3040904@xxxxxxxxxx>
User-agent: Mutt/1.5.20 (2009-06-14)
On Sun, Sep 22, 2013 at 04:25:15PM +0800, Jeff Liu wrote:
> From: Jie Liu <jeff.liu@xxxxxxxxxx>
> 
> At xfs_iext_realloc_direct(), the new_size is changed by adding
> if_bytes if originally the extent records are stored at the inline
> extent buffer, and we have to switch from it to a direct extent
> list for those new allocated extents, this is wrong. e.g,
> 
> Create a file with three extents which was showing as following,
> 
> xfs_io -f -c "truncate 100m" /xfs/testme
> 
> for i in $(seq 0 5 10); do
>       offset=$(($i * $((1 << 20))))
>       xfs_io -c "pwrite $offset 1m" /xfs/testme
> done
> 
> Inline
> ------
> irec: if_bytes        bytes_diff      new_size
> 1st   0               16              16
> 2nd   16              16              32
> 
> Switching
> ---------                                             rnew_size
> 3rd   32              16              48 + 32 = 80    roundup=128
> 
> In this case, the desired value of new_size should be 48, and then
> it will be roundup to 64 and be assigned to rnew_size.
> 
> However, this issue has been covered by resetting the if_bytes to
> the new_size which is calculated at the begnning of xfs_iext_add()
> before leaving out this function, and in turn make the rnew_size
> correctly again. Hence, this can not be detected via xfstestes.
> 
> This patch fix above problem and revise the new_size comments at
> xfs_iext_realloc_direct() to make it more readable.  Also, fix the
> comments while switching from the inline extent buffer to a direct
> extent list to reflect this change.
> 
> Signed-off-by: Jie Liu <jeff.liu@xxxxxxxxxx>

Applied.

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