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

["Darrick J. Wong" <djwong@kernel.org>]

On Mon, Aug 23, 2021 at 12:47:43PM +0530, Chandan Babu R wrote:
> On 23 Aug 2021 at 09:48, Chandan Babu R wrote:
> > On 28 Jul 2021 at 08:45, Chandan Babu R wrote:
> >> 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.
> >>
> >
> > Using XFS_MAX_[ATTR|DATA]_NEXTENTS won't be feasible later in the patch series
> > since the maximum extent count for the two inode forks depend on whether
> > XFS_SB_FEAT_INCOMPAT_NREXT64 feature bit is set or not. With the incompat
> > feature bit set, extent counts for attr and data forks can have maximum values
> > of (2^32 - 1) and (2^48 - 1) respectively. With the incompat feature bit not
> > set, extent counts for attr and data forks can have maximum values of (2^15 -
> > 1) and (2^31 - 1) respectively.
> >
> > Also, xfs_iext_max_nextents() (an inline function introduced in the next patch
> > in this series) abstracts away the logic of determining the maximum extent
> > count for an inode fork.
> 
> I think introducing xfs_iext_max_nextents() before renaming the max extent
> counter macros would reduce proliferation of XFS_IFORK_EXTCNT_MAX* macros
> across the source code. If you are ok with it, I will reorder the current
> patch and the next patch.

Sounds good to me. :)

--D

> -- 
> chandan