linux-kernel - Re: [PATCH 10/13] xfs: Unmap blocks according to forcealign

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Date: Mon, 24 Jun 2024 16:12:48 +0100
From: John Garry <john.g.garry@...cle.com>
To: "Darrick J. Wong" <djwong@...nel.org>
Cc: chandan.babu@...cle.com, dchinner@...hat.com, hch@....de,
        viro@...iv.linux.org.uk, brauner@...nel.org, jack@...e.cz,
        linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, catherine.hoang@...cle.com,
        martin.petersen@...cle.com
Subject: Re: [PATCH 10/13] xfs: Unmap blocks according to forcealign

On 21/06/2024 20:12, Darrick J. Wong wrote:
> On Fri, Jun 21, 2024 at 10:05:37AM +0000, John Garry wrote:
>> For when forcealign is enabled, blocks in an inode need to be unmapped
>> according to extent alignment, like what is already done for rtvol.
>>
>> Signed-off-by: John Garry <john.g.garry@...cle.com>
>> ---
>>   fs/xfs/libxfs/xfs_bmap.c | 38 +++++++++++++++++++++++++++++++++-----
>>   1 file changed, 33 insertions(+), 5 deletions(-)
>>
>> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
>> index c9cf138e13c4..ebeb2969b289 100644
>> --- a/fs/xfs/libxfs/xfs_bmap.c
>> +++ b/fs/xfs/libxfs/xfs_bmap.c
>> @@ -5380,6 +5380,25 @@ xfs_bmap_del_extent_real(
>>   	return 0;
>>   }
>>   
>> +static xfs_extlen_t
>> +xfs_bunmapi_align(
>> +	struct xfs_inode	*ip,
>> +	xfs_fsblock_t		bno)
>> +{
>> +	struct xfs_mount	*mp = ip->i_mount;
>> +	xfs_agblock_t		agbno;
>> +
>> +	if (xfs_inode_has_forcealign(ip)) {
>> +		if (is_power_of_2(ip->i_extsize))
>> +			return bno & (ip->i_extsize - 1);
>> +
>> +		agbno = XFS_FSB_TO_AGBNO(mp, bno);
>> +		return do_div(agbno, ip->i_extsize);
> 
> Huh.  The inode verifier allows realtime forcealign files, but this code
> will not handle that properly.  Either don't allow realtime files, or
> make this handle them correctly:

ok, so XFS_FSB_TO_AGBNO() is not always suitable

> 
> 	if (XFS_IS_REALTIME_INODE(ip)) {
> 		if (xfs_inode_has_forcealign(ip))
> 			return offset_in_block(bno, ip->i_extsize);
> 		return xfs_rtb_to_rtxoff(ip->i_mount, bno);
> 	} else if (xfs_inode_has_forcealign(ip)) {
> 		xfs_agblock_t	agbno = XFS_FSB_TO_AGBNO(mp, bno);
> 
> 		return offset_in_block(agbno, ip->i_extsize);
> 	}
> 
> 	return 1; /* or assert, or whatever */
> 
>> +	}
>> +	ASSERT(XFS_IS_REALTIME_INODE(ip));
>> +	return xfs_rtb_to_rtxoff(ip->i_mount, bno);
>> +}
>> +
>>   /*
>>    * Unmap (remove) blocks from a file.
>>    * If nexts is nonzero then the number of extents to remove is limited to
>> @@ -5402,6 +5421,7 @@ __xfs_bunmapi(
>>   	struct xfs_bmbt_irec	got;		/* current extent record */
>>   	struct xfs_ifork	*ifp;		/* inode fork pointer */
>>   	int			isrt;		/* freeing in rt area */
>> +	int			isforcealign;	/* freeing for inode with forcealign */
>>   	int			logflags;	/* transaction logging flags */
>>   	xfs_extlen_t		mod;		/* rt extent offset */
>>   	struct xfs_mount	*mp = ip->i_mount;
>> @@ -5439,6 +5459,8 @@ __xfs_bunmapi(
>>   	}
>>   	XFS_STATS_INC(mp, xs_blk_unmap);
>>   	isrt = xfs_ifork_is_realtime(ip, whichfork);
>> +	isforcealign = (whichfork != XFS_ATTR_FORK) &&
>> +			xfs_inode_has_forcealign(ip);
>>   	end = start + len;
>>   
>>   	if (!xfs_iext_lookup_extent_before(ip, ifp, &end, &icur, &got)) {
>> @@ -5490,11 +5512,10 @@ __xfs_bunmapi(
>>   		if (del.br_startoff + del.br_blockcount > end + 1)
>>   			del.br_blockcount = end + 1 - del.br_startoff;
>>   
>> -		if (!isrt || (flags & XFS_BMAPI_REMAP))
>> +		if ((!isrt && !isforcealign) || (flags & XFS_BMAPI_REMAP))
>>   			goto delete;
>>   
>> -		mod = xfs_rtb_to_rtxoff(mp,
>> -				del.br_startblock + del.br_blockcount);
>> +		mod = xfs_bunmapi_align(ip, del.br_startblock + del.br_blockcount);
>>   		if (mod) {
>>   			/*
>>   			 * Realtime extent not lined up at the end.
> 
> "Not aligned to allocation unit on the end." ?

ok

> 
>> @@ -5542,9 +5563,16 @@ __xfs_bunmapi(
>>   			goto nodelete;
>>   		}
>>   
>> -		mod = xfs_rtb_to_rtxoff(mp, del.br_startblock);
>> +		mod = xfs_bunmapi_align(ip, del.br_startblock);
>>   		if (mod) {
>> -			xfs_extlen_t off = mp->m_sb.sb_rextsize - mod;
>> +			xfs_extlen_t off;
>> +
>> +			if (isforcealign) {
>> +				off = ip->i_extsize - mod;
>> +			} else {
>> +				ASSERT(isrt);
>> +				off = mp->m_sb.sb_rextsize - mod;
>> +			}
>>   
>>   			/*
>>   			 * Realtime extent is lined up at the end but not
> 
> Same here -- now this code is handling more than just rt extents.
> 

ok

Thanks!