From: Dave Chinner <david@fromorbit.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: linux-xfs@vger.kernel.org, linux-mm@kvack.org,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 23/26] xfs: reclaim inodes from the LRU
Date: Thu, 31 Oct 2019 10:25:38 +1100 [thread overview]
Message-ID: <20191030232538.GR4614@dread.disaster.area> (raw)
In-Reply-To: <20191011105618.GE12811@infradead.org>
On Fri, Oct 11, 2019 at 03:56:18AM -0700, Christoph Hellwig wrote:
> > +++ b/fs/xfs/xfs_icache.c
> > @@ -1193,7 +1193,7 @@ xfs_reclaim_inode(
> > *
> > * Return the number of inodes freed.
> > */
> > -STATIC int
> > +int
> > xfs_reclaim_inodes_ag(
> > struct xfs_mount *mp,
> > int flags,
>
> This looks odd. This function actually is unused now. I think you
> want to fold in the patch that removes it instead of this little hack
> to make the compiler happy.
I think it might have been a stray.
>
> > - xfs_reclaim_inodes_ag(mp, SYNC_WAIT, INT_MAX);
> > + struct xfs_ireclaim_args *ra = arg;
> > + struct inode *inode = container_of(item, struct inode, i_lru);
> > + struct xfs_inode *ip = XFS_I(inode);
>
> Whitespace damage, and a line > 80 chars.
Fixed.
>
> > +out_ifunlock:
> > + xfs_ifunlock(ip);
>
> This error path will instantly deadlock, given that xfs_ifunlock takes
> i_flags_lock through xfs_iflags_clear, and we already hold it here.
Good catch. Clearly it's hard to hit a flush locked inode here...
> > + /*
> > + * Remove the inode from the per-AG radix tree.
> > + *
> > + * Because radix_tree_delete won't complain even if the item was never
> > + * added to the tree assert that it's been there before to catch
> > + * problems with the inode life time early on.
> > + */
> > + pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ino));
> > + spin_lock(&pag->pag_ici_lock);
> > + if (!radix_tree_delete(&pag->pag_ici_root, XFS_INO_TO_AGINO(mp, ino)))
> > + ASSERT(0);
>
> Well, it "complains" by returning NULL instead of the entry. So I think
> that comment could use some updates or simply be removed.
Removed.
>
> > +void
> > +xfs_dispose_inodes(
> > + struct list_head *freeable)
> > +{
> > + while (!list_empty(freeable)) {
> > + struct inode *inode;
> > +
> > + inode = list_first_entry(freeable, struct inode, i_lru);
>
> This could use list_first_entry_or_null in the while loop, or not.
> Or list_pop_entry if we had it, but Linus hates that :)
Changed to use list_first_entry_or_null().
>
> > +xfs_reclaim_inodes(
> > + struct xfs_mount *mp)
> > +{
> > + while (list_lru_count(&mp->m_inode_lru)) {
> > + struct xfs_ireclaim_args ra;
> > + long freed, to_free;
> > +
> > + INIT_LIST_HEAD(&ra.freeable);
> > + ra.lowest_lsn = NULLCOMMITLSN;
> > + to_free = list_lru_count(&mp->m_inode_lru);
>
> Do we want a helper to initialize the xfs_ireclaim_args? That would
> solve the "issue" of not initializing dirty_skipped in a few users
> and make it a little easier to use.
Done.
> > +
> > + freed = list_lru_walk(&mp->m_inode_lru, xfs_inode_reclaim_isolate,
>
> Line > 80 chars.
Fixed.
> > +static inline int __xfs_iflock_nowait(struct xfs_inode *ip)
> > +{
> > + if (ip->i_flags & XFS_IFLOCK)
> > + return false;
> > + ip->i_flags |= XFS_IFLOCK;
> > + return true;
> > +}
>
> I wonder if simply open coding this would be simpler, given how magic
> xfs_inode_reclaim_isolate already is, and given that we really shouldn't
> use this helper anywhere else.
Well, I kind of just added an __xfs_ifunlock() wrapper to pair with
it because of the deadlock you caught above. I've added
lockdep_assert_held() to both of them to indicate the context in
which they should be used. While it's special case, I really would
like to keep the internals of flush locking code together as much as
possible.
Longer term (i.e. a future patchset), I really want to clean up how
we use the i_flags_lock and the i_flags bits. At the time the iflags
wrappers made sense, but now we have as many open coded flags as we
do wrapped. And in many of these cases I think we'd be better off
using bitops for them (e.g. bitops for the flush lock bit make these
new helpers go away), and the i_flags_lock can be removed and
replaced by the VFS inode i_lock for operations that require an
internal spinlock to serialise...
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
next prev parent reply other threads:[~2019-10-30 23:25 UTC|newest]
Thread overview: 87+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-09 3:20 [PATCH V2 00/26] mm, xfs: non-blocking inode reclaim Dave Chinner
2019-10-09 3:20 ` [PATCH 01/26] xfs: Lower CIL flush limit for large logs Dave Chinner
2019-10-11 12:39 ` Brian Foster
2019-10-30 17:08 ` Darrick J. Wong
2019-10-09 3:21 ` [PATCH 02/26] xfs: Throttle commits on delayed background CIL push Dave Chinner
2019-10-11 12:38 ` Brian Foster
2019-10-09 3:21 ` [PATCH 03/26] xfs: don't allow log IO to be throttled Dave Chinner
2019-10-11 9:35 ` Christoph Hellwig
2019-10-11 12:39 ` Brian Foster
2019-10-30 17:14 ` Darrick J. Wong
2019-10-09 3:21 ` [PATCH 04/26] xfs: Improve metadata buffer reclaim accountability Dave Chinner
2019-10-11 12:39 ` Brian Foster
2019-10-11 12:57 ` Christoph Hellwig
2019-10-11 23:14 ` Dave Chinner
2019-10-11 23:13 ` Dave Chinner
2019-10-12 12:05 ` Brian Foster
2019-10-13 3:14 ` Dave Chinner
2019-10-14 13:05 ` Brian Foster
2019-10-30 17:25 ` Darrick J. Wong
2019-10-30 21:43 ` Dave Chinner
2019-10-31 3:06 ` Darrick J. Wong
2019-10-31 20:50 ` Dave Chinner
2019-10-31 21:05 ` Darrick J. Wong
2019-10-31 21:22 ` Christoph Hellwig
2019-11-03 21:26 ` Dave Chinner
2019-11-04 23:08 ` Darrick J. Wong
2019-10-09 3:21 ` [PATCH 05/26] xfs: correctly acount for reclaimable slabs Dave Chinner
2019-10-11 12:39 ` Brian Foster
2019-10-30 17:16 ` Darrick J. Wong
2019-10-09 3:21 ` [PATCH 06/26] xfs: synchronous AIL pushing Dave Chinner
2019-10-11 9:42 ` Christoph Hellwig
2019-10-11 12:40 ` Brian Foster
2019-10-11 23:15 ` Dave Chinner
2019-10-09 3:21 ` [PATCH 07/26] xfs: tail updates only need to occur when LSN changes Dave Chinner
2019-10-11 9:50 ` Christoph Hellwig
2019-10-11 12:40 ` Brian Foster
2019-10-09 3:21 ` [PATCH 08/26] mm: directed shrinker work deferral Dave Chinner
2019-10-14 8:46 ` Christoph Hellwig
2019-10-14 13:06 ` Brian Foster
2019-10-18 7:59 ` Dave Chinner
2019-10-09 3:21 ` [PATCH 09/26] shrinkers: use defer_work for GFP_NOFS sensitive shrinkers Dave Chinner
2019-10-09 3:21 ` [PATCH 10/26] mm: factor shrinker work calculations Dave Chinner
2019-10-09 3:21 ` [PATCH 11/26] shrinker: defer work only to kswapd Dave Chinner
2019-10-09 3:21 ` [PATCH 12/26] shrinker: clean up variable types and tracepoints Dave Chinner
2019-10-09 3:21 ` [PATCH 13/26] mm: reclaim_state records pages reclaimed, not slabs Dave Chinner
2019-10-09 3:21 ` [PATCH 14/26] mm: back off direct reclaim on excessive shrinker deferral Dave Chinner
2019-10-11 16:21 ` Matthew Wilcox
2019-10-11 23:20 ` Dave Chinner
2019-10-09 3:21 ` [PATCH 15/26] mm: kswapd backoff for shrinkers Dave Chinner
2019-10-09 3:21 ` [PATCH 16/26] xfs: synchronous AIL pushing Dave Chinner
2019-10-11 10:18 ` Christoph Hellwig
2019-10-11 15:29 ` Brian Foster
2019-10-11 23:27 ` Dave Chinner
2019-10-12 12:08 ` Brian Foster
2019-10-09 3:21 ` [PATCH 17/26] xfs: don't block kswapd in inode reclaim Dave Chinner
2019-10-11 15:29 ` Brian Foster
2019-10-09 3:21 ` [PATCH 18/26] xfs: reduce kswapd blocking on inode locking Dave Chinner
2019-10-11 10:29 ` Christoph Hellwig
2019-10-09 3:21 ` [PATCH 19/26] xfs: kill background reclaim work Dave Chinner
2019-10-11 10:31 ` Christoph Hellwig
2019-10-09 3:21 ` [PATCH 20/26] xfs: use AIL pushing for inode reclaim IO Dave Chinner
2019-10-11 17:38 ` Brian Foster
2019-10-09 3:21 ` [PATCH 21/26] xfs: remove mode from xfs_reclaim_inodes() Dave Chinner
2019-10-11 10:39 ` Christoph Hellwig
2019-10-14 13:07 ` Brian Foster
2019-10-09 3:21 ` [PATCH 22/26] xfs: track reclaimable inodes using a LRU list Dave Chinner
2019-10-11 10:42 ` Christoph Hellwig
2019-10-14 13:07 ` Brian Foster
2019-10-09 3:21 ` [PATCH 23/26] xfs: reclaim inodes from the LRU Dave Chinner
2019-10-11 10:56 ` Christoph Hellwig
2019-10-30 23:25 ` Dave Chinner [this message]
2019-10-09 3:21 ` [PATCH 24/26] xfs: remove unusued old inode reclaim code Dave Chinner
2019-10-09 3:21 ` [PATCH 25/26] xfs: rework unreferenced inode lookups Dave Chinner
2019-10-11 12:55 ` Christoph Hellwig
2019-10-11 13:39 ` Peter Zijlstra
2019-10-11 23:38 ` Dave Chinner
2019-10-14 13:07 ` Brian Foster
2019-10-17 1:24 ` Dave Chinner
2019-10-17 7:57 ` Brian Foster
2019-10-18 20:29 ` Dave Chinner
2019-10-09 3:21 ` [PATCH 26/26] xfs: use xfs_ail_push_all_sync in xfs_reclaim_inodes Dave Chinner
2019-10-11 9:55 ` Christoph Hellwig
2019-10-09 7:06 ` [PATCH V2 00/26] mm, xfs: non-blocking inode reclaim Christoph Hellwig
2019-10-11 19:03 ` Josef Bacik
2019-10-11 23:48 ` Dave Chinner
2019-10-12 0:19 ` Josef Bacik
2019-10-12 0:48 ` Dave Chinner
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