linux-kernel - [PATCH 0/6] dcache/namei fixes for lustre

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Date:   Wed, 02 Aug 2017 13:06:18 +1000
From:   NeilBrown <neilb@...e.com>
To:     Oleg Drokin <oleg.drokin@...el.com>,
        Greg Kroah-Hartman <greg@...ah.com>,
        Andreas Dilger <andreas.dilger@...el.com>
Cc:     Lustre Development List <lustre-devel@...ts.lustre.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH 0/6] dcache/namei fixes for lustre

This series is a revised version of two patches I sent
previously (one of which was sadly broken).
That patch has been broken into multiple parts for easy
review.  The other is included unchanged as the last of
this series.

I was drawn to look at this code due to the tests on
DCACHE_DISCONNECTED which are often wrong, and it turns out
they are used wrongly in lustre too.  Fixing one led to some
clean-up.  Fixing the other is straight forward.

A particular change here from the previous posting is
the first patch which tests for DCACHE_PAR_LOOKUP in ll_dcompare().
Without this patch, two threads can be looking up the same
name in a given directory in parallel.  This parallelism lead
to my concerns about needing improved locking in ll_splice_alias().
Instead of improving the locking, I now avoid the need for it
by fixing ll_dcompare.

This code passes basic "smoke tests".

Note that the cast to "struct dentry *" in the first patch is because
we have a "const struct dentry *" but d_in_lookup() requires a
pointer to a non-const structure.  I'll send a separate patch to
change d_in_lookup().

---

NeilBrown (6):
      staging: lustre: llite: handle DCACHE_PAR_LOOKUP in ll_dcompare
      staging: lustre: llite: use d_splice_alias for directories.
      staging: lustre: llite: remove directory-specific code from ll_find_alias()
      staging: lluste: llite: simplify ll_find_alias()
      staging: lustre: llite: refine ll_find_alias based on d_exact_alias
      staging: lustre: llite: fix incorrect DCACHE_DISCONNECTED test

 drivers/staging/lustre/lustre/llite/dcache.c       |   10 +++
 .../staging/lustre/lustre/llite/llite_internal.h   |    2 -
 drivers/staging/lustre/lustre/llite/namei.c        |   60 ++++++++++----------
 3 files changed, 40 insertions(+), 32 deletions(-)

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