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[v9,1/3] xfs: fix the calculation of length and end

Message ID 1675522718-88-2-git-send-email-ruansy.fnst@fujitsu.com (mailing list archive)
State New, archived
Headers show
Series mm, pmem, xfs: Introduce MF_MEM_REMOVE for unbind | expand

Commit Message

Shiyang Ruan Feb. 4, 2023, 2:58 p.m. UTC 
The end should be start + length - 1.  Also fix the calculation of the
length when seeking for intersection of notify range and device.

Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/xfs_notify_failure.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Comments

Matthew Wilcox (Oracle) Feb. 5, 2023, 11:42 a.m. UTC | #1 
On Sat, Feb 04, 2023 at 02:58:36PM +0000, Shiyang Ruan wrote:
> @@ -222,8 +222,8 @@ xfs_dax_notify_failure(
>  		len -= ddev_start - offset;
>  		offset = 0;
>  	}
> -	if (offset + len > ddev_end)
> -		len -= ddev_end - offset;
> +	if (offset + len - 1 > ddev_end)
> +		len -= offset + len - 1 - ddev_end;

This _looks_ wrong.  Are you sure it shouldn't be:

		len = ddev_end - offset + 1;
Shiyang Ruan Feb. 6, 2023, 6:45 a.m. UTC | #2 
在 2023/2/5 19:42, Matthew Wilcox 写道:
> On Sat, Feb 04, 2023 at 02:58:36PM +0000, Shiyang Ruan wrote:
>> @@ -222,8 +222,8 @@ xfs_dax_notify_failure(
>>   		len -= ddev_start - offset;
>>   		offset = 0;
>>   	}
>> -	if (offset + len > ddev_end)
>> -		len -= ddev_end - offset;
>> +	if (offset + len - 1 > ddev_end)
>> +		len -= offset + len - 1 - ddev_end;
> 
> This _looks_ wrong.  Are you sure it shouldn't be:
> 
> 		len = ddev_end - offset + 1;
> 

It is to make sure the range won't beyond the end of device.

But actually, both of us are rgiht.
   Mine: len -= offset + len - 1 - ddev_end;
      => len = len - (offset + len - 1 - ddev_end);
      => len = len - offset - len + 1 + ddev_end;
      => len = ddev_end - offset + 1;          --> Yours

I forgot to simplify it.  Will fix.


--
Thanks,
Ruan.
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Patch

diff --git a/fs/xfs/xfs_notify_failure.c b/fs/xfs/xfs_notify_failure.c
index c4078d0ec108..3830f908e215 100644
--- a/fs/xfs/xfs_notify_failure.c
+++ b/fs/xfs/xfs_notify_failure.c
@@ -114,7 +114,7 @@  xfs_dax_notify_ddev_failure(
 	int			error = 0;
 	xfs_fsblock_t		fsbno = XFS_DADDR_TO_FSB(mp, daddr);
 	xfs_agnumber_t		agno = XFS_FSB_TO_AGNO(mp, fsbno);
-	xfs_fsblock_t		end_fsbno = XFS_DADDR_TO_FSB(mp, daddr + bblen);
+	xfs_fsblock_t		end_fsbno = XFS_DADDR_TO_FSB(mp, daddr + bblen - 1);
 	xfs_agnumber_t		end_agno = XFS_FSB_TO_AGNO(mp, end_fsbno);
 
 	error = xfs_trans_alloc_empty(mp, &tp);
@@ -210,7 +210,7 @@  xfs_dax_notify_failure(
 	ddev_end = ddev_start + bdev_nr_bytes(mp->m_ddev_targp->bt_bdev) - 1;
 
 	/* Ignore the range out of filesystem area */
-	if (offset + len < ddev_start)
+	if (offset + len - 1 < ddev_start)
 		return -ENXIO;
 	if (offset > ddev_end)
 		return -ENXIO;
@@ -222,8 +222,8 @@  xfs_dax_notify_failure(
 		len -= ddev_start - offset;
 		offset = 0;
 	}
-	if (offset + len > ddev_end)
-		len -= ddev_end - offset;
+	if (offset + len - 1 > ddev_end)
+		len -= offset + len - 1 - ddev_end;
 
 	return xfs_dax_notify_ddev_failure(mp, BTOBB(offset), BTOBB(len),
 			mf_flags);