From: Ira Weiny <ira.weiny@intel.com>
To: Dave Chinner <david@fromorbit.com>
Cc: linux-kernel@vger.kernel.org,
Alexander Viro <viro@zeniv.linux.org.uk>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
Dan Williams <dan.j.williams@intel.com>,
Christoph Hellwig <hch@lst.de>,
"Theodore Y. Ts'o" <tytso@mit.edu>, Jan Kara <jack@suse.cz>,
linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH V4 02/13] fs/xfs: Clarify lockdep dependency for xfs_isilocked()
Date: Fri, 21 Feb 2020 15:00:44 -0800 [thread overview]
Message-ID: <20200221230043.GA6762@iweiny-DESK2.sc.intel.com> (raw)
In-Reply-To: <20200221013451.GU10776@dread.disaster.area>
On Fri, Feb 21, 2020 at 12:34:51PM +1100, Dave Chinner wrote:
> On Thu, Feb 20, 2020 at 04:41:23PM -0800, ira.weiny@intel.com wrote:
> > From: Ira Weiny <ira.weiny@intel.com>
> >
> > xfs_isilocked() can't work fully without CONFIG_LOCKDEP. However,
> > making xfs_isilocked() dependant on CONFIG_LOCKDEP is not feasible
> > because it is used for more than the i_rwsem. Therefore a short-circuit
> > was provided via debug_locks. However, this caused confusion while
> > working through the xfs locking.
> >
> > Rather than use debug_locks as a flag specify this clearly using
> > IS_ENABLED(CONFIG_LOCKDEP).
> >
> > Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> >
> > ---
> > Changes from V3:
> > Reordered to be a "pre-cleanup" patch
> >
> > Changes from V2:
> > This patch is new for V3
> > ---
> > fs/xfs/xfs_inode.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> > index c5077e6326c7..35df324875db 100644
> > --- a/fs/xfs/xfs_inode.c
> > +++ b/fs/xfs/xfs_inode.c
> > @@ -364,7 +364,7 @@ xfs_isilocked(
> >
> > if (lock_flags & (XFS_IOLOCK_EXCL|XFS_IOLOCK_SHARED)) {
> > if (!(lock_flags & XFS_IOLOCK_SHARED))
> > - return !debug_locks ||
> > + return !IS_ENABLED(CONFIG_LOCKDEP) ||
> > lockdep_is_held_type(&VFS_I(ip)->i_rwsem, 0);
>
> This breaks expected lockdep behaviour.
>
> We need to use debug_locks here because lockdep turns off lock
> checking via debug_locks when lockdep encounters a locking
> inconsistency. We only want to know about the first locking
> problem, not spew cascading lock problems over and over once we
> already know there is a locking problem.
Ah... ok... Seems like that should be part of the lockdep interface...
I'll drop the patch for now,
Ira
>
> IOWs, checking debug_locks is required here for the same reason it
> is used in lockdep_assert_held_{read/write}(). essentially we are
> open coding lockdep_assert_held_write() here because this function
> is only called from within ASSERT() statements and we don't want
> multiple WARN/BUGs being issued when this triggers....
>
> Cheers,
>
> Dave.
> --
> Dave Chinner
> david@fromorbit.com
next prev parent reply other threads:[~2020-02-21 23:00 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-21 0:41 [PATCH V4 00/13] Enable per-file/per-directory DAX operations V4 ira.weiny
2020-02-21 0:41 ` [PATCH V4 01/13] fs/xfs: Remove unnecessary initialization of i_rwsem ira.weiny
2020-02-21 1:26 ` Dave Chinner
2020-02-27 17:52 ` Ira Weiny
2020-02-21 0:41 ` [PATCH V4 02/13] fs/xfs: Clarify lockdep dependency for xfs_isilocked() ira.weiny
2020-02-21 1:34 ` Dave Chinner
2020-02-21 23:00 ` Ira Weiny [this message]
2020-02-21 0:41 ` [PATCH V4 03/13] fs: Remove unneeded IS_DAX() check ira.weiny
2020-02-21 1:42 ` Dave Chinner
2020-02-21 23:04 ` Ira Weiny
2020-02-21 17:42 ` Christoph Hellwig
2020-02-21 0:41 ` [PATCH V4 04/13] fs/stat: Define DAX statx attribute ira.weiny
2020-02-21 0:41 ` [PATCH V4 05/13] fs/xfs: Isolate the physical DAX flag from enabled ira.weiny
2020-02-21 0:41 ` [PATCH V4 06/13] fs/xfs: Create function xfs_inode_enable_dax() ira.weiny
2020-02-22 0:28 ` Darrick J. Wong
2020-02-23 15:07 ` Ira Weiny
2020-02-21 0:41 ` [PATCH V4 07/13] fs: Add locking for a dynamic address space operations state ira.weiny
2020-02-21 17:44 ` Christoph Hellwig
2020-02-21 22:44 ` Dave Chinner
2020-02-21 23:26 ` Dan Williams
2020-02-24 17:56 ` Christoph Hellwig
2020-02-25 0:09 ` Dave Chinner
2020-02-25 17:36 ` Christoph Hellwig
2020-02-25 19:37 ` Jeff Moyer
2020-02-26 9:28 ` Jonathan Halliday
2020-02-26 11:31 ` Jan Kara
2020-02-26 11:56 ` Jonathan Halliday
2020-02-26 16:10 ` Ira Weiny
2020-02-26 16:46 ` Dan Williams
2020-02-26 17:20 ` Jan Kara
2020-02-26 17:54 ` Dan Williams
2020-02-25 21:03 ` Ira Weiny
2020-02-26 11:17 ` Jan Kara
2020-02-26 15:57 ` Ira Weiny
2020-02-22 0:33 ` Darrick J. Wong
2020-02-23 15:03 ` Ira Weiny
2020-02-21 0:41 ` [PATCH V4 08/13] fs: Prevent DAX state change if file is mmap'ed ira.weiny
2020-02-21 0:41 ` [PATCH V4 09/13] fs/xfs: Add write aops lock to xfs layer ira.weiny
2020-02-22 0:31 ` Darrick J. Wong
2020-02-23 15:04 ` Ira Weiny
2020-02-24 0:34 ` Dave Chinner
2020-02-24 19:57 ` Ira Weiny
2020-02-24 22:32 ` Dave Chinner
2020-02-25 21:12 ` Ira Weiny
2020-02-25 22:59 ` Dave Chinner
2020-02-26 18:02 ` Ira Weiny
2020-02-21 0:41 ` [PATCH V4 10/13] fs/xfs: Clean up locking in dax invalidate ira.weiny
2020-02-21 17:45 ` Christoph Hellwig
2020-02-21 18:06 ` Ira Weiny
2020-02-21 0:41 ` [PATCH V4 11/13] fs/xfs: Allow toggle of effective DAX flag ira.weiny
2020-02-21 0:41 ` [PATCH V4 12/13] fs/xfs: Remove xfs_diflags_to_linux() ira.weiny
2020-02-21 0:41 ` [PATCH V4 13/13] Documentation/dax: Update Usage section ira.weiny
2020-02-26 22:48 ` [PATCH V4 00/13] Enable per-file/per-directory DAX operations V4 Jeff Moyer
2020-02-27 2:43 ` Ira Weiny
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200221230043.GA6762@iweiny-DESK2.sc.intel.com \
--to=ira.weiny@intel.com \
--cc=dan.j.williams@intel.com \
--cc=darrick.wong@oracle.com \
--cc=david@fromorbit.com \
--cc=hch@lst.de \
--cc=jack@suse.cz \
--cc=linux-ext4@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-xfs@vger.kernel.org \
--cc=tytso@mit.edu \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).