From: Dave Chinner <david@fromorbit.com>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Allison Collins <allison.henderson@oracle.com>,
linux-xfs <linux-xfs@vger.kernel.org>
Subject: Re: [PATCH v7 03/19] xfs: Add xfs_has_attr and subroutines
Date: Tue, 25 Feb 2020 17:26:12 +1100 [thread overview]
Message-ID: <20200225062612.GE10776@dread.disaster.area> (raw)
In-Reply-To: <CAOQ4uxiUVy3OfFsqx_KyirE6pD0XvnzNEehn7Vv4cxXw8kTSjQ@mail.gmail.com>
On Sun, Feb 23, 2020 at 02:20:32PM +0200, Amir Goldstein wrote:
> On Sun, Feb 23, 2020 at 4:07 AM Allison Collins
> <allison.henderson@oracle.com> wrote:
> >
> > From: Allison Henderson <allison.henderson@oracle.com>
> >
> > This patch adds a new functions to check for the existence of an attribute.
> > Subroutines are also added to handle the cases of leaf blocks, nodes or shortform.
> > Common code that appears in existing attr add and remove functions have been
> > factored out to help reduce the appearance of duplicated code. We will need these
> > routines later for delayed attributes since delayed operations cannot return error
> > codes.
> >
> > Signed-off-by: Allison Collins <allison.henderson@oracle.com>
> > ---
> > fs/xfs/libxfs/xfs_attr.c | 171 ++++++++++++++++++++++++++++--------------
> > fs/xfs/libxfs/xfs_attr.h | 1 +
> > fs/xfs/libxfs/xfs_attr_leaf.c | 111 +++++++++++++++++----------
> > fs/xfs/libxfs/xfs_attr_leaf.h | 3 +
> > 4 files changed, 188 insertions(+), 98 deletions(-)
> >
> > diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> > index 9acdb23..2255060 100644
> > --- a/fs/xfs/libxfs/xfs_attr.c
> > +++ b/fs/xfs/libxfs/xfs_attr.c
> > @@ -46,6 +46,7 @@ STATIC int xfs_attr_shortform_addname(xfs_da_args_t *args);
> > STATIC int xfs_attr_leaf_get(xfs_da_args_t *args);
> > STATIC int xfs_attr_leaf_addname(xfs_da_args_t *args);
> > STATIC int xfs_attr_leaf_removename(xfs_da_args_t *args);
> > +STATIC int xfs_attr_leaf_hasname(struct xfs_da_args *args, struct xfs_buf **bp);
> >
> > /*
> > * Internal routines when attribute list is more than one block.
> > @@ -53,6 +54,8 @@ STATIC int xfs_attr_leaf_removename(xfs_da_args_t *args);
> > STATIC int xfs_attr_node_get(xfs_da_args_t *args);
> > STATIC int xfs_attr_node_addname(xfs_da_args_t *args);
> > STATIC int xfs_attr_node_removename(xfs_da_args_t *args);
> > +STATIC int xfs_attr_node_hasname(xfs_da_args_t *args,
> > + struct xfs_da_state **state);
> > STATIC int xfs_attr_fillstate(xfs_da_state_t *state);
> > STATIC int xfs_attr_refillstate(xfs_da_state_t *state);
> >
> > @@ -310,6 +313,37 @@ xfs_attr_set_args(
> > }
> >
> > /*
> > + * Return EEXIST if attr is found, or ENOATTR if not
>
> This is a very silly return value for a function named has_attr in my taste.
> I realize you inherited this interface from xfs_attr3_leaf_lookup_int(), but
> IMO this change looks like a very good opportunity to change that internal
> API:
tl;dr Cleaning up this API is work for another patchset.
>
> xfs_has_attr?
>
> 0: NO
> 1: YES (or stay with the syscall standard of -ENOATTR)
> <0: error
While I agree with your sentiment, Amir, the API you suggest is an
anti-pattern. We've been removing ternary return value APIs like
this from XFS and replacing them with an explicit error return value
and an operational return parameter like so:
error = xfs_has_attr(&exists)
if (error)
return error;
if (!exists && REPLACE) {
error = -ENOATTR;
goto out_error_release;
}
if (exists && CREATE) {
error = -EEXIST;
goto out_error_release;
}
.....
out_error_release:
xfs_trans_brelse(args->trans, bp);
return error;
This allows us to separate out fatal metadata fetch and parsing
errors from the operational logic that is run on the status returned
from a successful function call.
IMO, this sort of API change needs to be driven right down into
the internal functions that generate ENOATTR/EEXIST in the first
place. Otherwise all we are doing here is forcing the new code to
translate ENOATTR/EEXIST to some intermediate error code that the
higher layer code then has to convert back to ENOATTR/EEXIST so that
it's callers function properly.
Hence I don't think chagning this API just for this new function
makes the code simpler or easier to maintain. And I don't really
think changing the entire API is in the scope of this work. Hence,
even though I don't like the API, I think it is fine to be retained
for this patchset.
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2020-02-25 6:26 UTC|newest]
Thread overview: 135+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-23 2:05 [PATCH v7 00/19] xfs: Delayed Ready Attrs Allison Collins
2020-02-23 2:05 ` [PATCH v7 01/19] xfs: Replace attribute parameters with struct xfs_name Allison Collins
2020-02-23 9:34 ` Amir Goldstein
2020-02-23 16:03 ` Allison Collins
2020-02-25 0:49 ` Dave Chinner
2020-02-24 12:08 ` Chandan Rajendra
2020-02-24 16:25 ` Allison Collins
2020-02-24 13:06 ` Brian Foster
2020-02-24 16:25 ` Allison Collins
2020-02-23 2:05 ` [PATCH v7 02/19] xfs: Embed struct xfs_name in xfs_da_args Allison Collins
2020-02-23 11:54 ` Amir Goldstein
2020-02-23 16:51 ` Allison Collins
2020-02-24 6:50 ` Amir Goldstein
2020-02-24 7:36 ` Allison Collins
2020-02-24 7:43 ` Amir Goldstein
2020-02-25 0:57 ` Dave Chinner
2020-02-25 2:00 ` Allison Collins
2020-02-25 4:06 ` Dave Chinner
2020-02-25 4:19 ` Allison Collins
2020-02-25 4:27 ` Darrick J. Wong
2020-02-25 6:07 ` Allison Collins
2020-02-25 6:30 ` Dave Chinner
2020-02-25 17:21 ` Christoph Hellwig
2020-02-25 6:56 ` Chandan Rajendra
2020-02-25 23:26 ` Allison Collins
2020-02-23 2:05 ` [PATCH v7 03/19] xfs: Add xfs_has_attr and subroutines Allison Collins
2020-02-23 12:20 ` Amir Goldstein
2020-02-23 17:28 ` Allison Collins
2020-02-24 6:58 ` Amir Goldstein
2020-02-25 6:26 ` Dave Chinner [this message]
2020-02-25 6:43 ` Amir Goldstein
2020-02-25 22:27 ` Dave Chinner
2020-02-24 13:08 ` Brian Foster
2020-02-24 21:18 ` Allison Collins
2020-02-25 13:25 ` Brian Foster
2020-02-26 2:31 ` Allison Collins
2020-02-25 9:49 ` Chandan Rajendra
2020-02-25 10:15 ` Chandan Rajendra
2020-02-26 2:19 ` Allison Collins
2020-02-26 2:18 ` Allison Collins
2020-02-23 2:05 ` [PATCH v7 04/19] xfs: Check for -ENOATTR or -EEXIST Allison Collins
2020-02-23 12:25 ` Amir Goldstein
2020-02-23 17:33 ` Allison Collins
2020-02-24 13:08 ` Brian Foster
2020-02-24 21:18 ` Allison Collins
2020-02-23 2:05 ` [PATCH v7 05/19] xfs: Factor out new helper functions xfs_attr_rmtval_set Allison Collins
2020-02-25 12:53 ` Chandan Rajendra
2020-02-26 2:20 ` Allison Collins
2020-02-23 2:05 ` [PATCH v7 06/19] xfs: Factor out trans handling in xfs_attr3_leaf_flipflags Allison Collins
2020-02-23 12:30 ` Amir Goldstein
2020-02-23 17:36 ` Allison Collins
2020-02-28 4:56 ` Chandan Rajendra
2020-02-23 2:05 ` [PATCH v7 07/19] xfs: Factor out xfs_attr_leaf_addname helper Allison Collins
2020-02-23 12:42 ` Amir Goldstein
2020-02-23 18:38 ` Allison Collins
2020-02-24 6:38 ` Amir Goldstein
2020-02-24 7:09 ` Allison Collins
2020-02-24 7:27 ` Amir Goldstein
2020-02-25 6:42 ` Dave Chinner
2020-02-25 13:26 ` Brian Foster
2020-02-25 23:26 ` Allison Collins
2020-02-28 6:51 ` Chandan Rajendra
2020-02-23 2:06 ` [PATCH v7 08/19] xfs: Refactor xfs_attr_try_sf_addname Allison Collins
2020-02-23 13:04 ` Amir Goldstein
2020-02-23 17:51 ` Allison Collins
2020-02-24 13:08 ` Brian Foster
2020-02-24 21:19 ` Allison Collins
2020-02-28 7:42 ` Chandan Rajendra
2020-02-28 18:14 ` Allison Collins
2020-02-23 2:06 ` [PATCH v7 09/19] xfs: Factor out trans roll from xfs_attr3_leaf_setflag Allison Collins
2020-02-28 7:59 ` Chandan Rajendra
2020-02-23 2:06 ` [PATCH v7 10/19] xfs: Factor out xfs_attr_rmtval_invalidate Allison Collins
2020-02-28 10:42 ` Chandan Rajendra
2020-02-23 2:06 ` [PATCH v7 11/19] xfs: Factor out trans roll in xfs_attr3_leaf_clearflag Allison Collins
2020-02-28 10:56 ` Chandan Rajendra
2020-02-23 2:06 ` [PATCH v7 12/19] xfs: Add helper function xfs_attr_rmtval_unmap Allison Collins
2020-02-24 13:40 ` Brian Foster
2020-02-24 21:44 ` Allison Collins
2020-02-25 13:27 ` Brian Foster
2020-02-26 3:29 ` Allison Collins
2020-02-26 13:47 ` Brian Foster
2020-02-25 7:21 ` Dave Chinner
2020-02-25 23:27 ` Allison Collins
2020-02-28 14:22 ` Chandan Rajendra
2020-02-23 2:06 ` [PATCH v7 13/19] xfs: Add delay ready attr remove routines Allison Collins
2020-02-24 15:25 ` Brian Foster
2020-02-24 17:03 ` Brian Foster
2020-02-24 23:14 ` Allison Collins
2020-02-24 23:56 ` Darrick J. Wong
2020-02-25 13:34 ` Brian Foster
2020-02-26 5:36 ` Allison Collins
2020-02-26 13:48 ` Brian Foster
2020-02-26 19:23 ` Allison Collins
2020-02-25 8:57 ` Dave Chinner
2020-02-26 0:57 ` Allison Collins
2020-02-26 22:34 ` Dave Chinner
2020-02-27 4:18 ` Allison Collins
2020-03-03 5:03 ` Chandan Rajendra
2020-03-03 5:40 ` Allison Collins
2020-02-23 2:06 ` [PATCH v7 14/19] xfs: Add delay ready attr set routines Allison Collins
2020-03-03 13:41 ` Chandan Rajendra
2020-03-03 17:07 ` Allison Collins
2020-02-23 2:06 ` [PATCH v7 15/19] xfs: Add helper function xfs_attr_node_shrink Allison Collins
2020-02-23 13:22 ` Amir Goldstein
2020-02-23 18:41 ` Allison Collins
2020-02-25 9:05 ` Dave Chinner
2020-02-26 1:48 ` Allison Collins
2020-02-23 2:06 ` [PATCH v7 16/19] xfs: Simplify xfs_attr_set_iter Allison Collins
2020-02-23 13:26 ` Amir Goldstein
2020-02-23 18:42 ` Allison Collins
2020-02-25 9:21 ` Dave Chinner
2020-02-26 2:13 ` Allison Collins
2020-02-26 22:39 ` Dave Chinner
2020-03-04 4:30 ` Chandan Rajendra
2020-03-04 17:04 ` Allison Collins
2020-03-05 3:39 ` Chandan Rajendra
2020-02-23 2:06 ` [PATCH v7 17/19] xfs: Add helper function xfs_attr_leaf_mark_incomplete Allison Collins
2020-02-23 13:47 ` Amir Goldstein
2020-02-23 18:43 ` Allison Collins
2020-02-25 9:31 ` Dave Chinner
2020-02-26 2:17 ` Allison Collins
2020-03-04 4:37 ` Chandan Rajendra
2020-02-23 2:06 ` [PATCH v7 18/19] xfs: Add remote block helper functions Allison Collins
2020-02-23 13:45 ` Amir Goldstein
2020-03-04 4:59 ` Chandan Rajendra
2020-02-23 2:06 ` [PATCH v7 19/19] xfs: Remove xfs_attr_rmtval_remove Allison Collins
2020-02-23 13:54 ` Amir Goldstein
2020-02-23 18:50 ` Allison Collins
2020-02-23 7:55 ` [PATCH v7 00/19] xfs: Delayed Ready Attrs Amir Goldstein
2020-02-23 16:02 ` Allison Collins
2020-02-24 6:30 ` Amir Goldstein
2020-02-24 16:23 ` Allison Collins
2020-02-25 5:53 ` Amir Goldstein
2020-02-24 8:31 ` Chandan Rajendra
2020-02-25 9:52 ` Dave Chinner
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