Re: [PATCH V2 02/12] xfs: Rename MAXEXTNUM, MAXAEXTNUM to XFS_IFORK_EXTCNT_MAXS32, XFS_IFORK_EXTCNT_MAXS16

From: Chandan Babu R <chandanrlinux@gmail.com>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: linux-xfs@vger.kernel.org
Subject: Re: [PATCH V2 02/12] xfs: Rename MAXEXTNUM, MAXAEXTNUM to XFS_IFORK_EXTCNT_MAXS32, XFS_IFORK_EXTCNT_MAXS16
Date: Wed, 28 Jul 2021 08:45:36 +0530	[thread overview]
Message-ID: <87eebjw2lj.fsf@garuda> (raw)
In-Reply-To: <20210727220318.GN559212@magnolia>

On 28 Jul 2021 at 03:33, Darrick J. Wong wrote:
> On Tue, Jul 27, 2021 at 02:56:11PM -0700, Darrick J. Wong wrote:
>> On Mon, Jul 26, 2021 at 05:15:31PM +0530, Chandan Babu R wrote:
>> > In preparation for introducing larger extent count limits, this commit renames
>> > existing extent count limits based on their signedness and width.
>> > 
>> > Signed-off-by: Chandan Babu R <chandanrlinux@gmail.com>
>> > ---
>> >  fs/xfs/libxfs/xfs_bmap.c       | 4 ++--
>> >  fs/xfs/libxfs/xfs_format.h     | 8 ++++----
>> >  fs/xfs/libxfs/xfs_inode_buf.c  | 4 ++--
>> >  fs/xfs/libxfs/xfs_inode_fork.c | 3 ++-
>> >  fs/xfs/scrub/inode_repair.c    | 2 +-
>> >  5 files changed, 11 insertions(+), 10 deletions(-)
>> > 
>> > diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
>> > index f3c9a0ebb0a5..8f262405a5b5 100644
>> > --- a/fs/xfs/libxfs/xfs_bmap.c
>> > +++ b/fs/xfs/libxfs/xfs_bmap.c
>> > @@ -76,10 +76,10 @@ xfs_bmap_compute_maxlevels(
>> >  	 * available.
>> >  	 */
>> >  	if (whichfork == XFS_DATA_FORK) {
>> > -		maxleafents = MAXEXTNUM;
>> > +		maxleafents = XFS_IFORK_EXTCNT_MAXS32;
>> 
>> I'm not in love with these names, since they tell me roughly about the
>> size of the constant (which I could glean from the definition) but less
>> about when I would expect to find them.  How about:
>> 
>> #define XFS_MAX_DFORK_NEXTENTS    ((xfs_extnum_t) 0x7FFFFFFF)
>> #define XFS_MAX_AFORK_NEXTENTS    ((xfs_aextnum_t)0x00007FFF)
>
> Or, given that 'DFORK' already means 'ondisk fork', how about:
>
> XFS_MAX_DATA_NEXTENTS
> XFS_MAX_ATTR_NEXTENTS

Yes, I agree. These names are better. I will incorporate your suggestions
before posting V3.

>
> ?
>
> --D
>
>> 
>> and when we get to the iext64 feature (or whatever we end up calling it)
>> then we can define new ones:
>> 
>> #define XFS_MAX_DFORK_NEXTENTS64  ((xfs_extnum_t) 0xFFFFFFFFFFFF)
>> #define XFS_MAX_AFORK_NEXTENTS64  ((xfs_aextnum_t)0x0000FFFFFFFF)
>> 
>> or something like that.
>> 
>> >  		sz = xfs_bmdr_space_calc(MINDBTPTRS);
>> >  	} else {
>> > -		maxleafents = MAXAEXTNUM;
>> > +		maxleafents = XFS_IFORK_EXTCNT_MAXS16;
>> >  		sz = xfs_bmdr_space_calc(MINABTPTRS);
>> >  	}
>> >  	maxrootrecs = xfs_bmdr_maxrecs(sz, 0);
>> > diff --git a/fs/xfs/libxfs/xfs_format.h b/fs/xfs/libxfs/xfs_format.h
>> > index 37cca918d2ba..920e3f9c418f 100644
>> > --- a/fs/xfs/libxfs/xfs_format.h
>> > +++ b/fs/xfs/libxfs/xfs_format.h
>> > @@ -1110,11 +1110,11 @@ enum xfs_dinode_fmt {
>> >  	{ XFS_DINODE_FMT_UUID,		"uuid" }
>> >  
>> >  /*
>> > - * Max values for extlen, extnum, aextnum.
>> > + * Max values for extlen and disk inode's extent counters.
>> >   */
>> > -#define	MAXEXTLEN	((uint32_t)0x001fffff)	/* 21 bits */
>> 
>> As for MAXEXTLEN... would you mind tacking a new patch on the end to fix
>> its definition as well?  It /really/ ought to be based on the disk
>> format definitions and not open-coded.
>> 
>> #define XFS_MAX_EXTLEN		((xfs_extlen_t)(1 << BMBT_BLOCKCOUNT_BITLEN) - 1)
>> 
>> --D
>> 
>> > -#define	MAXEXTNUM	((int32_t)0x7fffffff)	/* signed int */
>> > -#define	MAXAEXTNUM	((int16_t)0x7fff)	/* signed short */
>> > +#define	MAXEXTLEN		((uint32_t)0x1fffff) /* 21 bits */
>> > +#define XFS_IFORK_EXTCNT_MAXS32 ((int32_t)0x7fffffff)  /* Signed 32-bits */
>> > +#define XFS_IFORK_EXTCNT_MAXS16 ((int16_t)0x7fff)      /* Signed 16-bits */
>> >  
>> >  /*
>> >   * Inode minimum and maximum sizes.
>> > diff --git a/fs/xfs/libxfs/xfs_inode_buf.c b/fs/xfs/libxfs/xfs_inode_buf.c
>> > index 5625df1ddd95..66d13e8fa420 100644
>> > --- a/fs/xfs/libxfs/xfs_inode_buf.c
>> > +++ b/fs/xfs/libxfs/xfs_inode_buf.c
>> > @@ -365,9 +365,9 @@ xfs_dinode_verify_fork(
>> >  		break;
>> >  	case XFS_DINODE_FMT_BTREE:
>> >  		if (whichfork == XFS_ATTR_FORK) {
>> > -			if (di_nextents > MAXAEXTNUM)
>> > +			if (di_nextents > XFS_IFORK_EXTCNT_MAXS16)
>> >  				return __this_address;
>> > -		} else if (di_nextents > MAXEXTNUM) {
>> > +		} else if (di_nextents > XFS_IFORK_EXTCNT_MAXS32) {
>> >  			return __this_address;
>> >  		}
>> >  		break;
>> > diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
>> > index 801a6f7dbd0c..6f4b14d3d381 100644
>> > --- a/fs/xfs/libxfs/xfs_inode_fork.c
>> > +++ b/fs/xfs/libxfs/xfs_inode_fork.c
>> > @@ -736,7 +736,8 @@ xfs_iext_count_may_overflow(
>> >  	if (whichfork == XFS_COW_FORK)
>> >  		return 0;
>> >  
>> > -	max_exts = (whichfork == XFS_ATTR_FORK) ? MAXAEXTNUM : MAXEXTNUM;
>> > +	max_exts = (whichfork == XFS_ATTR_FORK) ?
>> > +		XFS_IFORK_EXTCNT_MAXS16 : XFS_IFORK_EXTCNT_MAXS32;
>> >  
>> >  	if (XFS_TEST_ERROR(false, ip->i_mount, XFS_ERRTAG_REDUCE_MAX_IEXTENTS))
>> >  		max_exts = 10;
>> > diff --git a/fs/xfs/scrub/inode_repair.c b/fs/xfs/scrub/inode_repair.c
>> > index a80cd633fe59..c44f8d06939b 100644
>> > --- a/fs/xfs/scrub/inode_repair.c
>> > +++ b/fs/xfs/scrub/inode_repair.c
>> > @@ -1198,7 +1198,7 @@ xrep_inode_blockcounts(
>> >  			return error;
>> >  		if (count >= sc->mp->m_sb.sb_dblocks)
>> >  			return -EFSCORRUPTED;
>> > -		if (nextents >= MAXAEXTNUM)
>> > +		if (nextents >= XFS_IFORK_EXTCNT_MAXS16)
>> >  			return -EFSCORRUPTED;
>> >  		ifp->if_nextents = nextents;
>> >  	} else {
>> > -- 
>> > 2.30.2
>> > 

-- 
chandan