[PATCH 24/26] xfs: remove unusued old inode reclaim code

From: Dave Chinner <david@fromorbit.com>
To: linux-xfs@vger.kernel.org
Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org
Subject: [PATCH 24/26] xfs: remove unusued old inode reclaim code
Date: Wed,  9 Oct 2019 14:21:22 +1100	[thread overview]
Message-ID: <20191009032124.10541-25-david@fromorbit.com> (raw)
In-Reply-To: <20191009032124.10541-1-david@fromorbit.com>

From: Dave Chinner <dchinner@redhat.com>

We don't use the custom AG radix tree walker, the reclaim radix tree
tag, the reclaimable inode counters, etc, so remove the all now.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 fs/xfs/xfs_icache.c | 411 +-------------------------------------------
 fs/xfs/xfs_icache.h |   7 +-
 fs/xfs/xfs_mount.c  |   4 -
 fs/xfs/xfs_mount.h  |   3 -
 fs/xfs/xfs_super.c  |   5 +-
 5 files changed, 6 insertions(+), 424 deletions(-)

diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index ef9ef46cfe6c..a6de159c71c2 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -139,83 +139,6 @@ xfs_inode_free(
 	__xfs_inode_free(ip);
 }
 
-static void
-xfs_perag_set_reclaim_tag(
-	struct xfs_perag	*pag)
-{
-	struct xfs_mount	*mp = pag->pag_mount;
-
-	lockdep_assert_held(&pag->pag_ici_lock);
-	if (pag->pag_ici_reclaimable++)
-		return;
-
-	/* propagate the reclaim tag up into the perag radix tree */
-	spin_lock(&mp->m_perag_lock);
-	radix_tree_tag_set(&mp->m_perag_tree, pag->pag_agno,
-			   XFS_ICI_RECLAIM_TAG);
-	spin_unlock(&mp->m_perag_lock);
-
-	trace_xfs_perag_set_reclaim(mp, pag->pag_agno, -1, _RET_IP_);
-}
-
-static void
-xfs_perag_clear_reclaim_tag(
-	struct xfs_perag	*pag)
-{
-	struct xfs_mount	*mp = pag->pag_mount;
-
-	lockdep_assert_held(&pag->pag_ici_lock);
-	if (--pag->pag_ici_reclaimable)
-		return;
-
-	/* clear the reclaim tag from the perag radix tree */
-	spin_lock(&mp->m_perag_lock);
-	radix_tree_tag_clear(&mp->m_perag_tree, pag->pag_agno,
-			     XFS_ICI_RECLAIM_TAG);
-	spin_unlock(&mp->m_perag_lock);
-	trace_xfs_perag_clear_reclaim(mp, pag->pag_agno, -1, _RET_IP_);
-}
-
-
-/*
- * We set the inode flag atomically with the radix tree tag.
- * Once we get tag lookups on the radix tree, this inode flag
- * can go away.
- */
-void
-xfs_inode_set_reclaim_tag(
-	struct xfs_inode	*ip)
-{
-	struct xfs_mount	*mp = ip->i_mount;
-	struct xfs_perag	*pag;
-
-	pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino));
-	spin_lock(&pag->pag_ici_lock);
-	spin_lock(&ip->i_flags_lock);
-
-	radix_tree_tag_set(&pag->pag_ici_root, XFS_INO_TO_AGINO(mp, ip->i_ino),
-			   XFS_ICI_RECLAIM_TAG);
-	xfs_perag_set_reclaim_tag(pag);
-	__xfs_iflags_set(ip, XFS_IRECLAIMABLE);
-
-	list_lru_add(&mp->m_inode_lru, &VFS_I(ip)->i_lru);
-
-	spin_unlock(&ip->i_flags_lock);
-	spin_unlock(&pag->pag_ici_lock);
-	xfs_perag_put(pag);
-}
-
-STATIC void
-xfs_inode_clear_reclaim_tag(
-	struct xfs_perag	*pag,
-	xfs_ino_t		ino)
-{
-	radix_tree_tag_clear(&pag->pag_ici_root,
-			     XFS_INO_TO_AGINO(pag->pag_mount, ino),
-			     XFS_ICI_RECLAIM_TAG);
-	xfs_perag_clear_reclaim_tag(pag);
-}
-
 static void
 xfs_inew_wait(
 	struct xfs_inode	*ip)
@@ -397,18 +320,16 @@ xfs_iget_cache_hit(
 			goto out_error;
 		}
 
-		spin_lock(&pag->pag_ici_lock);
-		spin_lock(&ip->i_flags_lock);
 
 		/*
 		 * Clear the per-lifetime state in the inode as we are now
 		 * effectively a new inode and need to return to the initial
 		 * state before reuse occurs.
 		 */
+		spin_lock(&ip->i_flags_lock);
 		ip->i_flags &= ~XFS_IRECLAIM_RESET_FLAGS;
 		ip->i_flags |= XFS_INEW;
 		list_lru_del(&mp->m_inode_lru, &inode->i_lru);
-		xfs_inode_clear_reclaim_tag(pag, ip->i_ino);
 		inode->i_state = I_NEW;
 		ip->i_sick = 0;
 		ip->i_checked = 0;
@@ -417,7 +338,6 @@ xfs_iget_cache_hit(
 		init_rwsem(&inode->i_rwsem);
 
 		spin_unlock(&ip->i_flags_lock);
-		spin_unlock(&pag->pag_ici_lock);
 	} else {
 		/* If the VFS inode is being torn down, pause and try again. */
 		if (!igrab(inode)) {
@@ -968,335 +888,6 @@ xfs_inode_ag_iterator_tag(
 	return last_error;
 }
 
-/*
- * Grab the inode for reclaim.
- *
- * Return false if we aren't going to reclaim it, true if it is a reclaim
- * candidate.
- *
- * If the inode is clean or unreclaimable, return 0 to tell the caller it does
- * not require flushing. Otherwise return the log item lsn of the inode so the
- * caller can determine it's inode flush target.  If we get the clean/dirty
- * state wrong then it will be sorted in xfs_reclaim_inode() once we have locks
- * held.
- */
-STATIC bool
-xfs_reclaim_inode_grab(
-	struct xfs_inode	*ip,
-	int			flags,
-	xfs_lsn_t		*lsn)
-{
-	ASSERT(rcu_read_lock_held());
-	*lsn = 0;
-
-	/* quick check for stale RCU freed inode */
-	if (!ip->i_ino)
-		return false;
-
-	/*
-	 * Do unlocked checks to see if the inode already is being flushed or in
-	 * reclaim to avoid lock traffic. If the inode is not clean, return the
-	 * it's position in the AIL for the caller to push to.
-	 */
-	if (!xfs_inode_clean(ip)) {
-		*lsn = ip->i_itemp->ili_item.li_lsn;
-		return false;
-	}
-
-	if (__xfs_iflags_test(ip, XFS_IFLOCK | XFS_IRECLAIM))
-		return false;
-
-	/*
-	 * The radix tree lock here protects a thread in xfs_iget from racing
-	 * with us starting reclaim on the inode.  Once we have the
-	 * XFS_IRECLAIM flag set it will not touch us.
-	 *
-	 * Due to RCU lookup, we may find inodes that have been freed and only
-	 * have XFS_IRECLAIM set.  Indeed, we may see reallocated inodes that
-	 * aren't candidates for reclaim at all, so we must check the
-	 * XFS_IRECLAIMABLE is set first before proceeding to reclaim.
-	 */
-	spin_lock(&ip->i_flags_lock);
-	if (!__xfs_iflags_test(ip, XFS_IRECLAIMABLE) ||
-	    __xfs_iflags_test(ip, XFS_IRECLAIM)) {
-		/* not a reclaim candidate. */
-		spin_unlock(&ip->i_flags_lock);
-		return false;
-	}
-	__xfs_iflags_set(ip, XFS_IRECLAIM);
-	spin_unlock(&ip->i_flags_lock);
-	return true;
-}
-
-/*
- * Inodes in different states need to be treated differently. The following
- * table lists the inode states and the reclaim actions necessary:
- *
- *	inode state	     iflush ret		required action
- *      ---------------      ----------         ---------------
- *	bad			-		reclaim
- *	shutdown		EIO		unpin and reclaim
- *	clean, unpinned		0		reclaim
- *	stale, unpinned		0		reclaim
- *	clean, pinned(*)	0		requeue
- *	stale, pinned		EAGAIN		requeue
- *	dirty, async		-		requeue
- *	dirty, sync		0		reclaim
- *
- * (*) dgc: I don't think the clean, pinned state is possible but it gets
- * handled anyway given the order of checks implemented.
- *
- * Also, because we get the flush lock first, we know that any inode that has
- * been flushed delwri has had the flush completed by the time we check that
- * the inode is clean.
- *
- * Note that because the inode is flushed delayed write by AIL pushing, the
- * flush lock may already be held here and waiting on it can result in very
- * long latencies.  Hence for sync reclaims, where we wait on the flush lock,
- * the caller should push the AIL first before trying to reclaim inodes to
- * minimise the amount of time spent waiting.  For background relaim, we only
- * bother to reclaim clean inodes anyway.
- *
- * Hence the order of actions after gaining the locks should be:
- *	bad		=> reclaim
- *	shutdown	=> unpin and reclaim
- *	pinned, async	=> requeue
- *	pinned, sync	=> unpin
- *	stale		=> reclaim
- *	clean		=> reclaim
- *	dirty, async	=> requeue
- *	dirty, sync	=> flush, wait and reclaim
- *
- * Returns true if the inode was reclaimed, false otherwise.
- */
-STATIC bool
-xfs_reclaim_inode(
-	struct xfs_inode	*ip,
-	struct xfs_perag	*pag,
-	xfs_lsn_t		*lsn)
-{
-	xfs_ino_t		ino;
-
-	*lsn = 0;
-
-	/*
-	 * Don't try to flush the inode if another inode in this cluster has
-	 * already flushed it after we did the initial checks in
-	 * xfs_reclaim_inode_grab().
-	 */
-	if (!xfs_ilock_nowait(ip, XFS_ILOCK_EXCL))
-		goto out;
-	if (!xfs_iflock_nowait(ip))
-		goto out_unlock;
-
-	/* If we are in shutdown, we don't care about blocking. */
-	if (XFS_FORCED_SHUTDOWN(ip->i_mount)) {
-		xfs_iunpin_wait(ip);
-		/* xfs_iflush_abort() drops the flush lock */
-		xfs_iflush_abort(ip, false);
-		goto reclaim;
-	}
-
-	/*
-	 * If it is pinned, we don't have an LSN we can push the AIL to - just
-	 * an LSN that we can push the CIL with. We don't want to block doing
-	 * that, so we'll just skip over this one without triggering writeback
-	 * for now.
-	 */
-	if (xfs_ipincount(ip))
-		goto out_ifunlock;
-
-	/*
-	 * Dirty inode we didn't catch, skip it.
-	 */
-	if (!xfs_inode_clean(ip) && !xfs_iflags_test(ip, XFS_ISTALE)) {
-		*lsn = ip->i_itemp->ili_item.li_lsn;
-		goto out_ifunlock;
-	}
-
-	/*
-	 * It's clean, we have it locked, we can now drop the flush lock
-	 * and reclaim it.
-	 */
-	xfs_ifunlock(ip);
-
-reclaim:
-	ASSERT(!xfs_isiflocked(ip));
-	ASSERT(xfs_inode_clean(ip) || xfs_iflags_test(ip, XFS_ISTALE));
-	ASSERT(ip->i_ino != 0);
-
-	/*
-	 * Because we use RCU freeing we need to ensure the inode always appears
-	 * to be reclaimed with an invalid inode number when in the free state.
-	 * We do this as early as possible under the ILOCK so that
-	 * xfs_iflush_cluster() and xfs_ifree_cluster() can be guaranteed to
-	 * detect races with us here. By doing this, we guarantee that once
-	 * xfs_iflush_cluster() or xfs_ifree_cluster() has locked XFS_ILOCK that
-	 * it will see either a valid inode that will serialise correctly, or it
-	 * will see an invalid inode that it can skip.
-	 */
-	spin_lock(&ip->i_flags_lock);
-	ino = ip->i_ino; /* for radix_tree_delete */
-	ip->i_flags = XFS_IRECLAIM;
-	ip->i_ino = 0;
-
-	/* XXX: temporary until lru based reclaim */
-	list_lru_del(&pag->pag_mount->m_inode_lru, &VFS_I(ip)->i_lru);
-	spin_unlock(&ip->i_flags_lock);
-
-	xfs_iunlock(ip, XFS_ILOCK_EXCL);
-
-	XFS_STATS_INC(ip->i_mount, xs_ig_reclaims);
-	/*
-	 * 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.
-	 */
-	spin_lock(&pag->pag_ici_lock);
-	if (!radix_tree_delete(&pag->pag_ici_root,
-				XFS_INO_TO_AGINO(ip->i_mount, ino)))
-		ASSERT(0);
-	xfs_perag_clear_reclaim_tag(pag);
-	spin_unlock(&pag->pag_ici_lock);
-
-	/*
-	 * Here we do an (almost) spurious inode lock in order to coordinate
-	 * with inode cache radix tree lookups.  This is because the lookup
-	 * can reference the inodes in the cache without taking references.
-	 *
-	 * We make that OK here by ensuring that we wait until the inode is
-	 * unlocked after the lookup before we go ahead and free it.
-	 */
-	xfs_ilock(ip, XFS_ILOCK_EXCL);
-	xfs_qm_dqdetach(ip);
-	xfs_iunlock(ip, XFS_ILOCK_EXCL);
-
-	__xfs_inode_free(ip);
-	return true;
-
-out_ifunlock:
-	xfs_ifunlock(ip);
-out_unlock:
-	xfs_iunlock(ip, XFS_ILOCK_EXCL);
-out:
-	xfs_iflags_clear(ip, XFS_IRECLAIM);
-	return false;
-}
-
-/*
- * Walk the AGs and reclaim the inodes in them. Even if the filesystem is
- * corrupted, we still want to try to reclaim all the inodes. If we don't,
- * then a shut down during filesystem unmount reclaim walk leak all the
- * unreclaimed inodes.
- *
- * Return the number of inodes freed.
- */
-int
-xfs_reclaim_inodes_ag(
-	struct xfs_mount	*mp,
-	int			flags,
-	int			nr_to_scan)
-{
-	struct xfs_perag	*pag;
-	xfs_agnumber_t		ag;
-	xfs_lsn_t		lsn, lowest_lsn = NULLCOMMITLSN;
-	long			freed = 0;
-
-	ag = 0;
-	while ((pag = xfs_perag_get_tag(mp, ag, XFS_ICI_RECLAIM_TAG))) {
-		unsigned long	first_index = 0;
-		int		done = 0;
-		int		nr_found = 0;
-
-		ag = pag->pag_agno + 1;
-		do {
-			struct xfs_inode *batch[XFS_LOOKUP_BATCH];
-			int	i;
-
-			mutex_lock(&pag->pag_ici_reclaim_lock);
-			first_index = pag->pag_ici_reclaim_cursor;
-
-			rcu_read_lock();
-			nr_found = radix_tree_gang_lookup_tag(
-					&pag->pag_ici_root,
-					(void **)batch, first_index,
-					XFS_LOOKUP_BATCH,
-					XFS_ICI_RECLAIM_TAG);
-			if (!nr_found) {
-				done = 1;
-				rcu_read_unlock();
-				break;
-			}
-
-			/*
-			 * Grab the inodes before we drop the lock. if we found
-			 * nothing, nr == 0 and the loop will be skipped.
-			 */
-			for (i = 0; i < nr_found; i++) {
-				struct xfs_inode *ip = batch[i];
-
-				if (done ||
-				    !xfs_reclaim_inode_grab(ip, flags, &lsn))
-					batch[i] = NULL;
-
-				if (lsn && XFS_LSN_CMP(lsn, lowest_lsn) < 0)
-					lowest_lsn = lsn;
-
-				/*
-				 * Update the index for the next lookup. Catch
-				 * overflows into the next AG range which can
-				 * occur if we have inodes in the last block of
-				 * the AG and we are currently pointing to the
-				 * last inode.
-				 *
-				 * Because we may see inodes that are from the
-				 * wrong AG due to RCU freeing and
-				 * reallocation, only update the index if it
-				 * lies in this AG. It was a race that lead us
-				 * to see this inode, so another lookup from
-				 * the same index will not find it again.
-				 */
-				if (XFS_INO_TO_AGNO(mp, ip->i_ino) !=
-								pag->pag_agno)
-					continue;
-				first_index = XFS_INO_TO_AGINO(mp, ip->i_ino + 1);
-				if (first_index < XFS_INO_TO_AGINO(mp, ip->i_ino))
-					done = 1;
-			}
-
-			/* unlock now we've grabbed the inodes. */
-			rcu_read_unlock();
-			if (!done)
-				pag->pag_ici_reclaim_cursor = first_index;
-			else
-				pag->pag_ici_reclaim_cursor = 0;
-			mutex_unlock(&pag->pag_ici_reclaim_lock);
-
-			for (i = 0; i < nr_found; i++) {
-				if (!batch[i])
-					continue;
-				if (xfs_reclaim_inode(batch[i], pag, &lsn))
-					freed++;
-				if (lsn && XFS_LSN_CMP(lsn, lowest_lsn) < 0)
-					lowest_lsn = lsn;
-			}
-
-			nr_to_scan -= XFS_LOOKUP_BATCH;
-			cond_resched();
-
-		} while (nr_found && !done && nr_to_scan > 0);
-
-		xfs_perag_put(pag);
-	}
-
-	if ((flags & SYNC_WAIT) && lowest_lsn != NULLCOMMITLSN)
-		xfs_ail_push_sync(mp->m_ail, lowest_lsn);
-
-	return freed;
-}
-
 enum lru_status
 xfs_inode_reclaim_isolate(
 	struct list_head	*item,
diff --git a/fs/xfs/xfs_icache.h b/fs/xfs/xfs_icache.h
index dadc69a30f33..0b4d06691275 100644
--- a/fs/xfs/xfs_icache.h
+++ b/fs/xfs/xfs_icache.h
@@ -25,9 +25,8 @@ struct xfs_eofblocks {
  */
 #define XFS_ICI_NO_TAG		(-1)	/* special flag for an untagged lookup
 					   in xfs_inode_ag_iterator */
-#define XFS_ICI_RECLAIM_TAG	0	/* inode is to be reclaimed */
-#define XFS_ICI_EOFBLOCKS_TAG	1	/* inode has blocks beyond EOF */
-#define XFS_ICI_COWBLOCKS_TAG	2	/* inode can have cow blocks to gc */
+#define XFS_ICI_EOFBLOCKS_TAG	0	/* inode has blocks beyond EOF */
+#define XFS_ICI_COWBLOCKS_TAG	1	/* inode can have cow blocks to gc */
 
 /*
  * Flags for xfs_iget()
@@ -60,8 +59,6 @@ enum lru_status xfs_inode_reclaim_isolate(struct list_head *item,
 void xfs_dispose_inodes(struct list_head *freeable);
 void xfs_reclaim_inodes(struct xfs_mount *mp);
 
-void xfs_inode_set_reclaim_tag(struct xfs_inode *ip);
-
 void xfs_inode_set_eofblocks_tag(struct xfs_inode *ip);
 void xfs_inode_clear_eofblocks_tag(struct xfs_inode *ip);
 int xfs_icache_free_eofblocks(struct xfs_mount *, struct xfs_eofblocks *);
diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 3a38fe7c4f8d..32c6bc186c14 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -148,7 +148,6 @@ xfs_free_perag(
 		ASSERT(atomic_read(&pag->pag_ref) == 0);
 		xfs_iunlink_destroy(pag);
 		xfs_buf_hash_destroy(pag);
-		mutex_destroy(&pag->pag_ici_reclaim_lock);
 		call_rcu(&pag->rcu_head, __xfs_free_perag);
 	}
 }
@@ -200,7 +199,6 @@ xfs_initialize_perag(
 		pag->pag_agno = index;
 		pag->pag_mount = mp;
 		spin_lock_init(&pag->pag_ici_lock);
-		mutex_init(&pag->pag_ici_reclaim_lock);
 		INIT_RADIX_TREE(&pag->pag_ici_root, GFP_ATOMIC);
 		if (xfs_buf_hash_init(pag))
 			goto out_free_pag;
@@ -242,7 +240,6 @@ xfs_initialize_perag(
 out_hash_destroy:
 	xfs_buf_hash_destroy(pag);
 out_free_pag:
-	mutex_destroy(&pag->pag_ici_reclaim_lock);
 	kmem_free(pag);
 out_unwind_new_pags:
 	/* unwind any prior newly initialized pags */
@@ -252,7 +249,6 @@ xfs_initialize_perag(
 			break;
 		xfs_buf_hash_destroy(pag);
 		xfs_iunlink_destroy(pag);
-		mutex_destroy(&pag->pag_ici_reclaim_lock);
 		kmem_free(pag);
 	}
 	return error;
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index f1e4c2eae984..ef63357da7af 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -383,9 +383,6 @@ typedef struct xfs_perag {
 
 	spinlock_t	pag_ici_lock;	/* incore inode cache lock */
 	struct radix_tree_root pag_ici_root;	/* incore inode cache root */
-	int		pag_ici_reclaimable;	/* reclaimable inodes */
-	struct mutex	pag_ici_reclaim_lock;	/* serialisation point */
-	unsigned long	pag_ici_reclaim_cursor;	/* reclaim restart point */
 
 	/* buffer cache index */
 	spinlock_t	pag_buf_lock;	/* lock for pag_buf_hash */
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 3dfddd3a443b..a706862994c8 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -945,7 +945,6 @@ xfs_fs_destroy_inode(
 	spin_lock(&ip->i_flags_lock);
 	ASSERT_ALWAYS(!__xfs_iflags_test(ip, XFS_IRECLAIMABLE));
 	ASSERT_ALWAYS(!__xfs_iflags_test(ip, XFS_IRECLAIM));
-	spin_unlock(&ip->i_flags_lock);
 
 	/*
 	 * We always use background reclaim here because even if the
@@ -954,7 +953,9 @@ xfs_fs_destroy_inode(
 	 * this more efficiently than we can here, so simply let background
 	 * reclaim tear down all inodes.
 	 */
-	xfs_inode_set_reclaim_tag(ip);
+	__xfs_iflags_set(ip, XFS_IRECLAIMABLE);
+	list_lru_add(&mp->m_inode_lru, &VFS_I(ip)->i_lru);
+	spin_unlock(&ip->i_flags_lock);
 }
 
 static void
-- 
2.23.0.rc1

