[PATCH 3/5] xfs: simplify tagged perag iteration

[PATCH 3/5] xfs: simplify tagged perag iteration

[Christoph Hellwig]

Pass the old perag structure to the tagged loop helpers so that they can
grab the old agno before releasing the reference.  This removes the need
to separately track the agno and the iterator macro, and thus also
obsoletes the for_each_perag_tag syntactic sugar.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/xfs_icache.c | 69 +++++++++++++++++++++------------------------
 fs/xfs/xfs_trace.h  |  4 +--
 2 files changed, 34 insertions(+), 39 deletions(-)

diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index ac604640d36229..4d71fbfe71299a 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -296,60 +296,63 @@ xfs_perag_clear_inode_tag(
  * Search from @first to find the next perag with the given tag set.
  */
 static struct xfs_perag *
-xfs_perag_get_tag(
+xfs_perag_get_next_tag(
 	struct xfs_mount	*mp,
-	xfs_agnumber_t		first,
+	struct xfs_perag	*pag,
 	unsigned int		tag)
 {
-	struct xfs_perag	*pag;
+	unsigned long		index = 0;
 	int			found;
 
+	if (pag) {
+		index = pag->pag_agno + 1;
+		xfs_perag_rele(pag);
+	}
+
 	rcu_read_lock();
 	found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
-					(void **)&pag, first, 1, tag);
+					(void **)&pag, index, 1, tag);
 	if (found <= 0) {
 		rcu_read_unlock();
 		return NULL;
 	}
-	trace_xfs_perag_get_tag(pag, _RET_IP_);
+	trace_xfs_perag_get_next_tag(pag, _RET_IP_);
 	atomic_inc(&pag->pag_ref);
 	rcu_read_unlock();
 	return pag;
 }
 
 /*
- * Search from @first to find the next perag with the given tag set.
+ * Find the next AG after @pag, or the first AG if @pag is NULL.
  */
 static struct xfs_perag *
-xfs_perag_grab_tag(
+xfs_perag_grab_next_tag(
 	struct xfs_mount	*mp,
-	xfs_agnumber_t		first,
+	struct xfs_perag	*pag,
 	int			tag)
 {
-	struct xfs_perag	*pag;
+	unsigned long		index = 0;
 	int			found;
 
+	if (pag) {
+		index = pag->pag_agno + 1;
+		xfs_perag_rele(pag);
+	}
+
 	rcu_read_lock();
 	found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
-					(void **)&pag, first, 1, tag);
+					(void **)&pag, index, 1, tag);
 	if (found <= 0) {
 		rcu_read_unlock();
 		return NULL;
 	}
-	trace_xfs_perag_grab_tag(pag, _RET_IP_);
+	trace_xfs_perag_grab_next_tag(pag, _RET_IP_);
 	if (!atomic_inc_not_zero(&pag->pag_active_ref))
 		pag = NULL;
 	rcu_read_unlock();
 	return pag;
 }
 
-#define for_each_perag_tag(mp, agno, pag, tag) \
-	for ((agno) = 0, (pag) = xfs_perag_grab_tag((mp), 0, (tag)); \
-		(pag) != NULL; \
-		(agno) = (pag)->pag_agno + 1, \
-		xfs_perag_rele(pag), \
-		(pag) = xfs_perag_grab_tag((mp), (agno), (tag)))
-
 /*
  * When we recycle a reclaimable inode, we need to re-initialise the VFS inode
  * part of the structure. This is made more complex by the fact we store
@@ -1077,15 +1080,11 @@ long
 xfs_reclaim_inodes_count(
 	struct xfs_mount	*mp)
 {
-	struct xfs_perag	*pag;
-	xfs_agnumber_t		ag = 0;
+	struct xfs_perag	*pag = NULL;
 	long			reclaimable = 0;
 
-	while ((pag = xfs_perag_get_tag(mp, ag, XFS_ICI_RECLAIM_TAG))) {
-		ag = pag->pag_agno + 1;
+	while ((pag = xfs_perag_get_next_tag(mp, pag, XFS_ICI_RECLAIM_TAG)))
 		reclaimable += pag->pag_ici_reclaimable;
-		xfs_perag_put(pag);
-	}
 	return reclaimable;
 }
 
@@ -1427,14 +1426,13 @@ void
 xfs_blockgc_start(
 	struct xfs_mount	*mp)
 {
-	struct xfs_perag	*pag;
-	xfs_agnumber_t		agno;
+	struct xfs_perag	*pag = NULL;
 
 	if (xfs_set_blockgc_enabled(mp))
 		return;
 
 	trace_xfs_blockgc_start(mp, __return_address);
-	for_each_perag_tag(mp, agno, pag, XFS_ICI_BLOCKGC_TAG)
+	while ((pag = xfs_perag_grab_next_tag(mp, pag, XFS_ICI_BLOCKGC_TAG)))
 		xfs_blockgc_queue(pag);
 }
 
@@ -1550,21 +1548,19 @@ int
 xfs_blockgc_flush_all(
 	struct xfs_mount	*mp)
 {
-	struct xfs_perag	*pag;
-	xfs_agnumber_t		agno;
+	struct xfs_perag	*pag = NULL;
 
 	trace_xfs_blockgc_flush_all(mp, __return_address);
 
 	/*
-	 * For each blockgc worker, move its queue time up to now.  If it
-	 * wasn't queued, it will not be requeued.  Then flush whatever's
-	 * left.
+	 * For each blockgc worker, move its queue time up to now.  If it wasn't
+	 * queued, it will not be requeued.  Then flush whatever is left.
 	 */
-	for_each_perag_tag(mp, agno, pag, XFS_ICI_BLOCKGC_TAG)
+	while ((pag = xfs_perag_grab_next_tag(mp, pag, XFS_ICI_BLOCKGC_TAG)))
 		mod_delayed_work(pag->pag_mount->m_blockgc_wq,
 				&pag->pag_blockgc_work, 0);
 
-	for_each_perag_tag(mp, agno, pag, XFS_ICI_BLOCKGC_TAG)
+	while ((pag = xfs_perag_grab_next_tag(mp, pag, XFS_ICI_BLOCKGC_TAG)))
 		flush_delayed_work(&pag->pag_blockgc_work);
 
 	return xfs_inodegc_flush(mp);
@@ -1810,12 +1806,11 @@ xfs_icwalk(
 	enum xfs_icwalk_goal	goal,
 	struct xfs_icwalk	*icw)
 {
-	struct xfs_perag	*pag;
+	struct xfs_perag	*pag = NULL;
 	int			error = 0;
 	int			last_error = 0;
-	xfs_agnumber_t		agno;
 
-	for_each_perag_tag(mp, agno, pag, goal) {
+	while ((pag = xfs_perag_grab_next_tag(mp, pag, goal))) {
 		error = xfs_icwalk_ag(pag, goal, icw);
 		if (error) {
 			last_error = error;
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 180ce697305a92..002d012ebd83cb 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -210,11 +210,11 @@ DEFINE_EVENT(xfs_perag_class, name,	\
 	TP_PROTO(struct xfs_perag *pag, unsigned long caller_ip), \
 	TP_ARGS(pag, caller_ip))
 DEFINE_PERAG_REF_EVENT(xfs_perag_get);
-DEFINE_PERAG_REF_EVENT(xfs_perag_get_tag);
+DEFINE_PERAG_REF_EVENT(xfs_perag_get_next_tag);
 DEFINE_PERAG_REF_EVENT(xfs_perag_hold);
 DEFINE_PERAG_REF_EVENT(xfs_perag_put);
 DEFINE_PERAG_REF_EVENT(xfs_perag_grab);
-DEFINE_PERAG_REF_EVENT(xfs_perag_grab_tag);
+DEFINE_PERAG_REF_EVENT(xfs_perag_grab_next_tag);
 DEFINE_PERAG_REF_EVENT(xfs_perag_rele);
 DEFINE_PERAG_REF_EVENT(xfs_perag_set_inode_tag);
 DEFINE_PERAG_REF_EVENT(xfs_perag_clear_inode_tag);
-- 
2.43.0

Re: [PATCH 3/5] xfs: simplify tagged perag iteration

[Darrick J. Wong]

On Wed, Aug 21, 2024 at 08:38:30AM +0200, Christoph Hellwig wrote:
> Pass the old perag structure to the tagged loop helpers so that they can
> grab the old agno before releasing the reference.  This removes the need
> to separately track the agno and the iterator macro, and thus also
> obsoletes the for_each_perag_tag syntactic sugar.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  fs/xfs/xfs_icache.c | 69 +++++++++++++++++++++------------------------
>  fs/xfs/xfs_trace.h  |  4 +--
>  2 files changed, 34 insertions(+), 39 deletions(-)
> 
> diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
> index ac604640d36229..4d71fbfe71299a 100644
> --- a/fs/xfs/xfs_icache.c
> +++ b/fs/xfs/xfs_icache.c
> @@ -296,60 +296,63 @@ xfs_perag_clear_inode_tag(
>   * Search from @first to find the next perag with the given tag set.
>   */
>  static struct xfs_perag *
> -xfs_perag_get_tag(
> +xfs_perag_get_next_tag(
>  	struct xfs_mount	*mp,
> -	xfs_agnumber_t		first,
> +	struct xfs_perag	*pag,
>  	unsigned int		tag)
>  {
> -	struct xfs_perag	*pag;
> +	unsigned long		index = 0;
>  	int			found;
>  
> +	if (pag) {
> +		index = pag->pag_agno + 1;
> +		xfs_perag_rele(pag);
> +	}

Please update the comment to reflect the replacement of @first with
@pag, and be sure to note that one starts the iteration by passing in
@pag == null, like you did below.

--D

> +
>  	rcu_read_lock();
>  	found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
> -					(void **)&pag, first, 1, tag);
> +					(void **)&pag, index, 1, tag);
>  	if (found <= 0) {
>  		rcu_read_unlock();
>  		return NULL;
>  	}
> -	trace_xfs_perag_get_tag(pag, _RET_IP_);
> +	trace_xfs_perag_get_next_tag(pag, _RET_IP_);
>  	atomic_inc(&pag->pag_ref);
>  	rcu_read_unlock();
>  	return pag;
>  }
>  
>  /*
> - * Search from @first to find the next perag with the given tag set.
> + * Find the next AG after @pag, or the first AG if @pag is NULL.
>   */
>  static struct xfs_perag *
> -xfs_perag_grab_tag(
> +xfs_perag_grab_next_tag(
>  	struct xfs_mount	*mp,
> -	xfs_agnumber_t		first,
> +	struct xfs_perag	*pag,
>  	int			tag)
>  {
> -	struct xfs_perag	*pag;
> +	unsigned long		index = 0;
>  	int			found;
>  
> +	if (pag) {
> +		index = pag->pag_agno + 1;
> +		xfs_perag_rele(pag);
> +	}
> +
>  	rcu_read_lock();
>  	found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
> -					(void **)&pag, first, 1, tag);
> +					(void **)&pag, index, 1, tag);
>  	if (found <= 0) {
>  		rcu_read_unlock();
>  		return NULL;
>  	}
> -	trace_xfs_perag_grab_tag(pag, _RET_IP_);
> +	trace_xfs_perag_grab_next_tag(pag, _RET_IP_);
>  	if (!atomic_inc_not_zero(&pag->pag_active_ref))
>  		pag = NULL;
>  	rcu_read_unlock();
>  	return pag;
>  }
>  
> -#define for_each_perag_tag(mp, agno, pag, tag) \
> -	for ((agno) = 0, (pag) = xfs_perag_grab_tag((mp), 0, (tag)); \
> -		(pag) != NULL; \
> -		(agno) = (pag)->pag_agno + 1, \
> -		xfs_perag_rele(pag), \
> -		(pag) = xfs_perag_grab_tag((mp), (agno), (tag)))
> -
>  /*
>   * When we recycle a reclaimable inode, we need to re-initialise the VFS inode
>   * part of the structure. This is made more complex by the fact we store
> @@ -1077,15 +1080,11 @@ long
>  xfs_reclaim_inodes_count(
>  	struct xfs_mount	*mp)
>  {
> -	struct xfs_perag	*pag;
> -	xfs_agnumber_t		ag = 0;
> +	struct xfs_perag	*pag = NULL;
>  	long			reclaimable = 0;
>  
> -	while ((pag = xfs_perag_get_tag(mp, ag, XFS_ICI_RECLAIM_TAG))) {
> -		ag = pag->pag_agno + 1;
> +	while ((pag = xfs_perag_get_next_tag(mp, pag, XFS_ICI_RECLAIM_TAG)))
>  		reclaimable += pag->pag_ici_reclaimable;
> -		xfs_perag_put(pag);
> -	}
>  	return reclaimable;
>  }
>  
> @@ -1427,14 +1426,13 @@ void
>  xfs_blockgc_start(
>  	struct xfs_mount	*mp)
>  {
> -	struct xfs_perag	*pag;
> -	xfs_agnumber_t		agno;
> +	struct xfs_perag	*pag = NULL;
>  
>  	if (xfs_set_blockgc_enabled(mp))
>  		return;
>  
>  	trace_xfs_blockgc_start(mp, __return_address);
> -	for_each_perag_tag(mp, agno, pag, XFS_ICI_BLOCKGC_TAG)
> +	while ((pag = xfs_perag_grab_next_tag(mp, pag, XFS_ICI_BLOCKGC_TAG)))
>  		xfs_blockgc_queue(pag);
>  }
>  
> @@ -1550,21 +1548,19 @@ int
>  xfs_blockgc_flush_all(
>  	struct xfs_mount	*mp)
>  {
> -	struct xfs_perag	*pag;
> -	xfs_agnumber_t		agno;
> +	struct xfs_perag	*pag = NULL;
>  
>  	trace_xfs_blockgc_flush_all(mp, __return_address);
>  
>  	/*
> -	 * For each blockgc worker, move its queue time up to now.  If it
> -	 * wasn't queued, it will not be requeued.  Then flush whatever's
> -	 * left.
> +	 * For each blockgc worker, move its queue time up to now.  If it wasn't
> +	 * queued, it will not be requeued.  Then flush whatever is left.
>  	 */
> -	for_each_perag_tag(mp, agno, pag, XFS_ICI_BLOCKGC_TAG)
> +	while ((pag = xfs_perag_grab_next_tag(mp, pag, XFS_ICI_BLOCKGC_TAG)))
>  		mod_delayed_work(pag->pag_mount->m_blockgc_wq,
>  				&pag->pag_blockgc_work, 0);
>  
> -	for_each_perag_tag(mp, agno, pag, XFS_ICI_BLOCKGC_TAG)
> +	while ((pag = xfs_perag_grab_next_tag(mp, pag, XFS_ICI_BLOCKGC_TAG)))
>  		flush_delayed_work(&pag->pag_blockgc_work);
>  
>  	return xfs_inodegc_flush(mp);
> @@ -1810,12 +1806,11 @@ xfs_icwalk(
>  	enum xfs_icwalk_goal	goal,
>  	struct xfs_icwalk	*icw)
>  {
> -	struct xfs_perag	*pag;
> +	struct xfs_perag	*pag = NULL;
>  	int			error = 0;
>  	int			last_error = 0;
> -	xfs_agnumber_t		agno;
>  
> -	for_each_perag_tag(mp, agno, pag, goal) {
> +	while ((pag = xfs_perag_grab_next_tag(mp, pag, goal))) {
>  		error = xfs_icwalk_ag(pag, goal, icw);
>  		if (error) {
>  			last_error = error;
> diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
> index 180ce697305a92..002d012ebd83cb 100644
> --- a/fs/xfs/xfs_trace.h
> +++ b/fs/xfs/xfs_trace.h
> @@ -210,11 +210,11 @@ DEFINE_EVENT(xfs_perag_class, name,	\
>  	TP_PROTO(struct xfs_perag *pag, unsigned long caller_ip), \
>  	TP_ARGS(pag, caller_ip))
>  DEFINE_PERAG_REF_EVENT(xfs_perag_get);
> -DEFINE_PERAG_REF_EVENT(xfs_perag_get_tag);
> +DEFINE_PERAG_REF_EVENT(xfs_perag_get_next_tag);
>  DEFINE_PERAG_REF_EVENT(xfs_perag_hold);
>  DEFINE_PERAG_REF_EVENT(xfs_perag_put);
>  DEFINE_PERAG_REF_EVENT(xfs_perag_grab);
> -DEFINE_PERAG_REF_EVENT(xfs_perag_grab_tag);
> +DEFINE_PERAG_REF_EVENT(xfs_perag_grab_next_tag);
>  DEFINE_PERAG_REF_EVENT(xfs_perag_rele);
>  DEFINE_PERAG_REF_EVENT(xfs_perag_set_inode_tag);
>  DEFINE_PERAG_REF_EVENT(xfs_perag_clear_inode_tag);
> -- 
> 2.43.0
> 
> 

convert XFS perag lookup to xarrays v3

[Christoph Hellwig]

Hi all,

for a project with the pending RT group code in XFS that reuses the basic
perag concepts I'd much prefer to use xarrays over the old radix tree for
nicer iteration semantics.

This series converts the perag code to xarrays to keep them in sync and
throws in the use of kfree_rcu_mightsleep in the same area.

Changes since v2:
 - fix a comment (which gets removed in a later patch)

Changes since v1:
 - use xa_insert instead of reinventing it
 - split API changes into separate patches
 - simplify tagged iteration
 - use the proper xa_mark_t type for marks to make sparse happy

Diffstat:
 libxfs/xfs_ag.c |   94 +++++---------------------------------------------------
 libxfs/xfs_ag.h |   14 --------
 xfs_icache.c    |   85 +++++++++++++++++++++++++++++++++++---------------
 xfs_mount.h     |    3 -
 xfs_super.c     |    3 -
 xfs_trace.h     |    4 +-
 6 files changed, 72 insertions(+), 131 deletions(-)

[PATCH 1/5] xfs: use kfree_rcu_mightsleep to free the perag structures

[Christoph Hellwig]

Using the kfree_rcu_mightsleep is simpler and removes the need for a
rcu_head in the perag structure.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/libxfs/xfs_ag.c | 12 +-----------
 fs/xfs/libxfs/xfs_ag.h |  3 ---
 2 files changed, 1 insertion(+), 14 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_ag.c b/fs/xfs/libxfs/xfs_ag.c
index 7e80732cb54708..4b5a39a83f7aed 100644
--- a/fs/xfs/libxfs/xfs_ag.c
+++ b/fs/xfs/libxfs/xfs_ag.c
@@ -235,16 +235,6 @@ xfs_initialize_perag_data(
 	return error;
 }
 
-STATIC void
-__xfs_free_perag(
-	struct rcu_head	*head)
-{
-	struct xfs_perag *pag = container_of(head, struct xfs_perag, rcu_head);
-
-	ASSERT(!delayed_work_pending(&pag->pag_blockgc_work));
-	kfree(pag);
-}
-
 /*
  * Free up the per-ag resources associated with the mount structure.
  */
@@ -270,7 +260,7 @@ xfs_free_perag(
 		xfs_perag_rele(pag);
 		XFS_IS_CORRUPT(pag->pag_mount,
 				atomic_read(&pag->pag_active_ref) != 0);
-		call_rcu(&pag->rcu_head, __xfs_free_perag);
+		kfree_rcu_mightsleep(pag);
 	}
 }
 
diff --git a/fs/xfs/libxfs/xfs_ag.h b/fs/xfs/libxfs/xfs_ag.h
index 35de09a2516c70..d62c266c0b44d5 100644
--- a/fs/xfs/libxfs/xfs_ag.h
+++ b/fs/xfs/libxfs/xfs_ag.h
@@ -63,9 +63,6 @@ struct xfs_perag {
 	/* Blocks reserved for the reverse mapping btree. */
 	struct xfs_ag_resv	pag_rmapbt_resv;
 
-	/* for rcu-safe freeing */
-	struct rcu_head	rcu_head;
-
 	/* Precalculated geometry info */
 	xfs_agblock_t		block_count;
 	xfs_agblock_t		min_block;
-- 
2.43.0

[PATCH 2/5] xfs: move the tagged perag lookup helpers to xfs_icache.c

[Christoph Hellwig]

The tagged perag helpers are only used in xfs_icache.c in the kernel code
and not at all in xfsprogs.  Move them to xfs_icache.c in preparation for
switching to an xarray, for which I have no plan to implement the tagged
lookup functions for userspace.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/libxfs/xfs_ag.c | 51 -------------------------------------
 fs/xfs/libxfs/xfs_ag.h | 11 --------
 fs/xfs/xfs_icache.c    | 58 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 58 insertions(+), 62 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_ag.c b/fs/xfs/libxfs/xfs_ag.c
index 4b5a39a83f7aed..87f00f0180846f 100644
--- a/fs/xfs/libxfs/xfs_ag.c
+++ b/fs/xfs/libxfs/xfs_ag.c
@@ -56,31 +56,6 @@ xfs_perag_get(
 	return pag;
 }
 
-/*
- * search from @first to find the next perag with the given tag set.
- */
-struct xfs_perag *
-xfs_perag_get_tag(
-	struct xfs_mount	*mp,
-	xfs_agnumber_t		first,
-	unsigned int		tag)
-{
-	struct xfs_perag	*pag;
-	int			found;
-
-	rcu_read_lock();
-	found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
-					(void **)&pag, first, 1, tag);
-	if (found <= 0) {
-		rcu_read_unlock();
-		return NULL;
-	}
-	trace_xfs_perag_get_tag(pag, _RET_IP_);
-	atomic_inc(&pag->pag_ref);
-	rcu_read_unlock();
-	return pag;
-}
-
 /* Get a passive reference to the given perag. */
 struct xfs_perag *
 xfs_perag_hold(
@@ -127,32 +102,6 @@ xfs_perag_grab(
 	return pag;
 }
 
-/*
- * search from @first to find the next perag with the given tag set.
- */
-struct xfs_perag *
-xfs_perag_grab_tag(
-	struct xfs_mount	*mp,
-	xfs_agnumber_t		first,
-	int			tag)
-{
-	struct xfs_perag	*pag;
-	int			found;
-
-	rcu_read_lock();
-	found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
-					(void **)&pag, first, 1, tag);
-	if (found <= 0) {
-		rcu_read_unlock();
-		return NULL;
-	}
-	trace_xfs_perag_grab_tag(pag, _RET_IP_);
-	if (!atomic_inc_not_zero(&pag->pag_active_ref))
-		pag = NULL;
-	rcu_read_unlock();
-	return pag;
-}
-
 void
 xfs_perag_rele(
 	struct xfs_perag	*pag)
diff --git a/fs/xfs/libxfs/xfs_ag.h b/fs/xfs/libxfs/xfs_ag.h
index d62c266c0b44d5..d9cccd093b60e0 100644
--- a/fs/xfs/libxfs/xfs_ag.h
+++ b/fs/xfs/libxfs/xfs_ag.h
@@ -153,15 +153,11 @@ void xfs_free_perag(struct xfs_mount *mp);
 
 /* Passive AG references */
 struct xfs_perag *xfs_perag_get(struct xfs_mount *mp, xfs_agnumber_t agno);
-struct xfs_perag *xfs_perag_get_tag(struct xfs_mount *mp, xfs_agnumber_t agno,
-		unsigned int tag);
 struct xfs_perag *xfs_perag_hold(struct xfs_perag *pag);
 void xfs_perag_put(struct xfs_perag *pag);
 
 /* Active AG references */
 struct xfs_perag *xfs_perag_grab(struct xfs_mount *, xfs_agnumber_t);
-struct xfs_perag *xfs_perag_grab_tag(struct xfs_mount *, xfs_agnumber_t,
-				   int tag);
 void xfs_perag_rele(struct xfs_perag *pag);
 
 /*
@@ -263,13 +259,6 @@ xfs_perag_next(
 	(agno) = 0; \
 	for_each_perag_from((mp), (agno), (pag))
 
-#define for_each_perag_tag(mp, agno, pag, tag) \
-	for ((agno) = 0, (pag) = xfs_perag_grab_tag((mp), 0, (tag)); \
-		(pag) != NULL; \
-		(agno) = (pag)->pag_agno + 1, \
-		xfs_perag_rele(pag), \
-		(pag) = xfs_perag_grab_tag((mp), (agno), (tag)))
-
 static inline struct xfs_perag *
 xfs_perag_next_wrap(
 	struct xfs_perag	*pag,
diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index cf629302d48e74..ac604640d36229 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -292,6 +292,64 @@ xfs_perag_clear_inode_tag(
 	trace_xfs_perag_clear_inode_tag(pag, _RET_IP_);
 }
 
+/*
+ * Search from @first to find the next perag with the given tag set.
+ */
+static struct xfs_perag *
+xfs_perag_get_tag(
+	struct xfs_mount	*mp,
+	xfs_agnumber_t		first,
+	unsigned int		tag)
+{
+	struct xfs_perag	*pag;
+	int			found;
+
+	rcu_read_lock();
+	found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
+					(void **)&pag, first, 1, tag);
+	if (found <= 0) {
+		rcu_read_unlock();
+		return NULL;
+	}
+	trace_xfs_perag_get_tag(pag, _RET_IP_);
+	atomic_inc(&pag->pag_ref);
+	rcu_read_unlock();
+	return pag;
+}
+
+/*
+ * Search from @first to find the next perag with the given tag set.
+ */
+static struct xfs_perag *
+xfs_perag_grab_tag(
+	struct xfs_mount	*mp,
+	xfs_agnumber_t		first,
+	int			tag)
+{
+	struct xfs_perag	*pag;
+	int			found;
+
+	rcu_read_lock();
+	found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
+					(void **)&pag, first, 1, tag);
+	if (found <= 0) {
+		rcu_read_unlock();
+		return NULL;
+	}
+	trace_xfs_perag_grab_tag(pag, _RET_IP_);
+	if (!atomic_inc_not_zero(&pag->pag_active_ref))
+		pag = NULL;
+	rcu_read_unlock();
+	return pag;
+}
+
+#define for_each_perag_tag(mp, agno, pag, tag) \
+	for ((agno) = 0, (pag) = xfs_perag_grab_tag((mp), 0, (tag)); \
+		(pag) != NULL; \
+		(agno) = (pag)->pag_agno + 1, \
+		xfs_perag_rele(pag), \
+		(pag) = xfs_perag_grab_tag((mp), (agno), (tag)))
+
 /*
  * When we recycle a reclaimable inode, we need to re-initialise the VFS inode
  * part of the structure. This is made more complex by the fact we store
-- 
2.43.0

[PATCH 3/5] xfs: simplify tagged perag iteration

[Christoph Hellwig]

Pass the old perag structure to the tagged loop helpers so that they can
grab the old agno before releasing the reference.  This removes the need
to separately track the agno and the iterator macro, and thus also
obsoletes the for_each_perag_tag syntactic sugar.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/xfs_icache.c | 71 +++++++++++++++++++++------------------------
 fs/xfs/xfs_trace.h  |  4 +--
 2 files changed, 35 insertions(+), 40 deletions(-)

diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index ac604640d36229..573743b1841fe7 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -293,63 +293,66 @@ xfs_perag_clear_inode_tag(
 }
 
 /*
- * Search from @first to find the next perag with the given tag set.
+ * Find the next AG after @pag, or the first AG if @pag is NULL.
  */
 static struct xfs_perag *
-xfs_perag_get_tag(
+xfs_perag_get_next_tag(
 	struct xfs_mount	*mp,
-	xfs_agnumber_t		first,
+	struct xfs_perag	*pag,
 	unsigned int		tag)
 {
-	struct xfs_perag	*pag;
+	unsigned long		index = 0;
 	int			found;
 
+	if (pag) {
+		index = pag->pag_agno + 1;
+		xfs_perag_rele(pag);
+	}
+
 	rcu_read_lock();
 	found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
-					(void **)&pag, first, 1, tag);
+					(void **)&pag, index, 1, tag);
 	if (found <= 0) {
 		rcu_read_unlock();
 		return NULL;
 	}
-	trace_xfs_perag_get_tag(pag, _RET_IP_);
+	trace_xfs_perag_get_next_tag(pag, _RET_IP_);
 	atomic_inc(&pag->pag_ref);
 	rcu_read_unlock();
 	return pag;
 }
 
 /*
- * Search from @first to find the next perag with the given tag set.
+ * Find the next AG after @pag, or the first AG if @pag is NULL.
  */
 static struct xfs_perag *
-xfs_perag_grab_tag(
+xfs_perag_grab_next_tag(
 	struct xfs_mount	*mp,
-	xfs_agnumber_t		first,
+	struct xfs_perag	*pag,
 	int			tag)
 {
-	struct xfs_perag	*pag;
+	unsigned long		index = 0;
 	int			found;
 
+	if (pag) {
+		index = pag->pag_agno + 1;
+		xfs_perag_rele(pag);
+	}
+
 	rcu_read_lock();
 	found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
-					(void **)&pag, first, 1, tag);
+					(void **)&pag, index, 1, tag);
 	if (found <= 0) {
 		rcu_read_unlock();
 		return NULL;
 	}
-	trace_xfs_perag_grab_tag(pag, _RET_IP_);
+	trace_xfs_perag_grab_next_tag(pag, _RET_IP_);
 	if (!atomic_inc_not_zero(&pag->pag_active_ref))
 		pag = NULL;
 	rcu_read_unlock();
 	return pag;
 }
 
-#define for_each_perag_tag(mp, agno, pag, tag) \
-	for ((agno) = 0, (pag) = xfs_perag_grab_tag((mp), 0, (tag)); \
-		(pag) != NULL; \
-		(agno) = (pag)->pag_agno + 1, \
-		xfs_perag_rele(pag), \
-		(pag) = xfs_perag_grab_tag((mp), (agno), (tag)))
-
 /*
  * When we recycle a reclaimable inode, we need to re-initialise the VFS inode
  * part of the structure. This is made more complex by the fact we store
@@ -1077,15 +1080,11 @@ long
 xfs_reclaim_inodes_count(
 	struct xfs_mount	*mp)
 {
-	struct xfs_perag	*pag;
-	xfs_agnumber_t		ag = 0;
+	struct xfs_perag	*pag = NULL;
 	long			reclaimable = 0;
 
-	while ((pag = xfs_perag_get_tag(mp, ag, XFS_ICI_RECLAIM_TAG))) {
-		ag = pag->pag_agno + 1;
+	while ((pag = xfs_perag_get_next_tag(mp, pag, XFS_ICI_RECLAIM_TAG)))
 		reclaimable += pag->pag_ici_reclaimable;
-		xfs_perag_put(pag);
-	}
 	return reclaimable;
 }
 
@@ -1427,14 +1426,13 @@ void
 xfs_blockgc_start(
 	struct xfs_mount	*mp)
 {
-	struct xfs_perag	*pag;
-	xfs_agnumber_t		agno;
+	struct xfs_perag	*pag = NULL;
 
 	if (xfs_set_blockgc_enabled(mp))
 		return;
 
 	trace_xfs_blockgc_start(mp, __return_address);
-	for_each_perag_tag(mp, agno, pag, XFS_ICI_BLOCKGC_TAG)
+	while ((pag = xfs_perag_grab_next_tag(mp, pag, XFS_ICI_BLOCKGC_TAG)))
 		xfs_blockgc_queue(pag);
 }
 
@@ -1550,21 +1548,19 @@ int
 xfs_blockgc_flush_all(
 	struct xfs_mount	*mp)
 {
-	struct xfs_perag	*pag;
-	xfs_agnumber_t		agno;
+	struct xfs_perag	*pag = NULL;
 
 	trace_xfs_blockgc_flush_all(mp, __return_address);
 
 	/*
-	 * For each blockgc worker, move its queue time up to now.  If it
-	 * wasn't queued, it will not be requeued.  Then flush whatever's
-	 * left.
+	 * For each blockgc worker, move its queue time up to now.  If it wasn't
+	 * queued, it will not be requeued.  Then flush whatever is left.
 	 */
-	for_each_perag_tag(mp, agno, pag, XFS_ICI_BLOCKGC_TAG)
+	while ((pag = xfs_perag_grab_next_tag(mp, pag, XFS_ICI_BLOCKGC_TAG)))
 		mod_delayed_work(pag->pag_mount->m_blockgc_wq,
 				&pag->pag_blockgc_work, 0);
 
-	for_each_perag_tag(mp, agno, pag, XFS_ICI_BLOCKGC_TAG)
+	while ((pag = xfs_perag_grab_next_tag(mp, pag, XFS_ICI_BLOCKGC_TAG)))
 		flush_delayed_work(&pag->pag_blockgc_work);
 
 	return xfs_inodegc_flush(mp);
@@ -1810,12 +1806,11 @@ xfs_icwalk(
 	enum xfs_icwalk_goal	goal,
 	struct xfs_icwalk	*icw)
 {
-	struct xfs_perag	*pag;
+	struct xfs_perag	*pag = NULL;
 	int			error = 0;
 	int			last_error = 0;
-	xfs_agnumber_t		agno;
 
-	for_each_perag_tag(mp, agno, pag, goal) {
+	while ((pag = xfs_perag_grab_next_tag(mp, pag, goal))) {
 		error = xfs_icwalk_ag(pag, goal, icw);
 		if (error) {
 			last_error = error;
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 180ce697305a92..002d012ebd83cb 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -210,11 +210,11 @@ DEFINE_EVENT(xfs_perag_class, name,	\
 	TP_PROTO(struct xfs_perag *pag, unsigned long caller_ip), \
 	TP_ARGS(pag, caller_ip))
 DEFINE_PERAG_REF_EVENT(xfs_perag_get);
-DEFINE_PERAG_REF_EVENT(xfs_perag_get_tag);
+DEFINE_PERAG_REF_EVENT(xfs_perag_get_next_tag);
 DEFINE_PERAG_REF_EVENT(xfs_perag_hold);
 DEFINE_PERAG_REF_EVENT(xfs_perag_put);
 DEFINE_PERAG_REF_EVENT(xfs_perag_grab);
-DEFINE_PERAG_REF_EVENT(xfs_perag_grab_tag);
+DEFINE_PERAG_REF_EVENT(xfs_perag_grab_next_tag);
 DEFINE_PERAG_REF_EVENT(xfs_perag_rele);
 DEFINE_PERAG_REF_EVENT(xfs_perag_set_inode_tag);
 DEFINE_PERAG_REF_EVENT(xfs_perag_clear_inode_tag);
-- 
2.43.0

[PATCH 4/5] xfs: convert perag lookup to xarray

[Christoph Hellwig]

Convert the perag lookup from the legacy radix tree to the xarray,
which allows for much nicer iteration and bulk lookup semantics.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/libxfs/xfs_ag.c | 31 +++++++-------------------
 fs/xfs/xfs_icache.c    | 50 +++++++++++++++++++++---------------------
 fs/xfs/xfs_mount.h     |  3 +--
 fs/xfs/xfs_super.c     |  3 +--
 4 files changed, 35 insertions(+), 52 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_ag.c b/fs/xfs/libxfs/xfs_ag.c
index 87f00f0180846f..5f0494702e0b55 100644
--- a/fs/xfs/libxfs/xfs_ag.c
+++ b/fs/xfs/libxfs/xfs_ag.c
@@ -46,7 +46,7 @@ xfs_perag_get(
 	struct xfs_perag	*pag;
 
 	rcu_read_lock();
-	pag = radix_tree_lookup(&mp->m_perag_tree, agno);
+	pag = xa_load(&mp->m_perags, agno);
 	if (pag) {
 		trace_xfs_perag_get(pag, _RET_IP_);
 		ASSERT(atomic_read(&pag->pag_ref) >= 0);
@@ -92,7 +92,7 @@ xfs_perag_grab(
 	struct xfs_perag	*pag;
 
 	rcu_read_lock();
-	pag = radix_tree_lookup(&mp->m_perag_tree, agno);
+	pag = xa_load(&mp->m_perags, agno);
 	if (pag) {
 		trace_xfs_perag_grab(pag, _RET_IP_);
 		if (!atomic_inc_not_zero(&pag->pag_active_ref))
@@ -195,9 +195,7 @@ xfs_free_perag(
 	xfs_agnumber_t		agno;
 
 	for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
-		spin_lock(&mp->m_perag_lock);
-		pag = radix_tree_delete(&mp->m_perag_tree, agno);
-		spin_unlock(&mp->m_perag_lock);
+		pag = xa_erase(&mp->m_perags, agno);
 		ASSERT(pag);
 		XFS_IS_CORRUPT(pag->pag_mount, atomic_read(&pag->pag_ref) != 0);
 		xfs_defer_drain_free(&pag->pag_intents_drain);
@@ -286,9 +284,7 @@ xfs_free_unused_perag_range(
 	xfs_agnumber_t		index;
 
 	for (index = agstart; index < agend; index++) {
-		spin_lock(&mp->m_perag_lock);
-		pag = radix_tree_delete(&mp->m_perag_tree, index);
-		spin_unlock(&mp->m_perag_lock);
+		pag = xa_erase(&mp->m_perags, index);
 		if (!pag)
 			break;
 		xfs_buf_cache_destroy(&pag->pag_bcache);
@@ -329,20 +325,11 @@ xfs_initialize_perag(
 		pag->pag_agno = index;
 		pag->pag_mount = mp;
 
-		error = radix_tree_preload(GFP_KERNEL | __GFP_RETRY_MAYFAIL);
-		if (error)
-			goto out_free_pag;
-
-		spin_lock(&mp->m_perag_lock);
-		if (radix_tree_insert(&mp->m_perag_tree, index, pag)) {
-			WARN_ON_ONCE(1);
-			spin_unlock(&mp->m_perag_lock);
-			radix_tree_preload_end();
-			error = -EEXIST;
+		error = xa_insert(&mp->m_perags, index, pag, GFP_KERNEL);
+		if (error) {
+			WARN_ON_ONCE(error == -EBUSY);
 			goto out_free_pag;
 		}
-		spin_unlock(&mp->m_perag_lock);
-		radix_tree_preload_end();
 
 #ifdef __KERNEL__
 		/* Place kernel structure only init below this point. */
@@ -390,9 +377,7 @@ xfs_initialize_perag(
 
 out_remove_pag:
 	xfs_defer_drain_free(&pag->pag_intents_drain);
-	spin_lock(&mp->m_perag_lock);
-	radix_tree_delete(&mp->m_perag_tree, index);
-	spin_unlock(&mp->m_perag_lock);
+	pag = xa_erase(&mp->m_perags, index);
 out_free_pag:
 	kfree(pag);
 out_unwind_new_pags:
diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index 573743b1841fe7..7ee32056897d58 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -65,6 +65,18 @@ static int xfs_icwalk_ag(struct xfs_perag *pag,
 					 XFS_ICWALK_FLAG_RECLAIM_SICK | \
 					 XFS_ICWALK_FLAG_UNION)
 
+/* Marks for the perag xarray */
+#define XFS_PERAG_RECLAIM_MARK	XA_MARK_0
+#define XFS_PERAG_BLOCKGC_MARK	XA_MARK_1
+
+static inline xa_mark_t ici_tag_to_mark(unsigned int tag)
+{
+	if (tag == XFS_ICI_RECLAIM_TAG)
+		return XFS_PERAG_RECLAIM_MARK;
+	ASSERT(tag == XFS_ICI_BLOCKGC_TAG);
+	return XFS_PERAG_BLOCKGC_MARK;
+}
+
 /*
  * Allocate and initialise an xfs_inode.
  */
@@ -191,7 +203,7 @@ xfs_reclaim_work_queue(
 {
 
 	rcu_read_lock();
-	if (radix_tree_tagged(&mp->m_perag_tree, XFS_ICI_RECLAIM_TAG)) {
+	if (xa_marked(&mp->m_perags, XFS_PERAG_RECLAIM_MARK)) {
 		queue_delayed_work(mp->m_reclaim_workqueue, &mp->m_reclaim_work,
 			msecs_to_jiffies(xfs_syncd_centisecs / 6 * 10));
 	}
@@ -241,9 +253,7 @@ xfs_perag_set_inode_tag(
 		return;
 
 	/* propagate the tag up into the perag radix tree */
-	spin_lock(&mp->m_perag_lock);
-	radix_tree_tag_set(&mp->m_perag_tree, pag->pag_agno, tag);
-	spin_unlock(&mp->m_perag_lock);
+	xa_set_mark(&mp->m_perags, pag->pag_agno, ici_tag_to_mark(tag));
 
 	/* start background work */
 	switch (tag) {
@@ -285,9 +295,7 @@ xfs_perag_clear_inode_tag(
 		return;
 
 	/* clear the tag from the perag radix tree */
-	spin_lock(&mp->m_perag_lock);
-	radix_tree_tag_clear(&mp->m_perag_tree, pag->pag_agno, tag);
-	spin_unlock(&mp->m_perag_lock);
+	xa_clear_mark(&mp->m_perags, pag->pag_agno, ici_tag_to_mark(tag));
 
 	trace_xfs_perag_clear_inode_tag(pag, _RET_IP_);
 }
@@ -302,7 +310,6 @@ xfs_perag_get_next_tag(
 	unsigned int		tag)
 {
 	unsigned long		index = 0;
-	int			found;
 
 	if (pag) {
 		index = pag->pag_agno + 1;
@@ -310,14 +317,11 @@ xfs_perag_get_next_tag(
 	}
 
 	rcu_read_lock();
-	found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
-					(void **)&pag, index, 1, tag);
-	if (found <= 0) {
-		rcu_read_unlock();
-		return NULL;
+	pag = xa_find(&mp->m_perags, &index, ULONG_MAX, ici_tag_to_mark(tag));
+	if (pag) {
+		trace_xfs_perag_get_next_tag(pag, _RET_IP_);
+		atomic_inc(&pag->pag_ref);
 	}
-	trace_xfs_perag_get_next_tag(pag, _RET_IP_);
-	atomic_inc(&pag->pag_ref);
 	rcu_read_unlock();
 	return pag;
 }
@@ -332,7 +336,6 @@ xfs_perag_grab_next_tag(
 	int			tag)
 {
 	unsigned long		index = 0;
-	int			found;
 
 	if (pag) {
 		index = pag->pag_agno + 1;
@@ -340,15 +343,12 @@ xfs_perag_grab_next_tag(
 	}
 
 	rcu_read_lock();
-	found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
-					(void **)&pag, index, 1, tag);
-	if (found <= 0) {
-		rcu_read_unlock();
-		return NULL;
+	pag = xa_find(&mp->m_perags, &index, ULONG_MAX, ici_tag_to_mark(tag));
+	if (pag) {
+		trace_xfs_perag_grab_next_tag(pag, _RET_IP_);
+		if (!atomic_inc_not_zero(&pag->pag_active_ref))
+			pag = NULL;
 	}
-	trace_xfs_perag_grab_next_tag(pag, _RET_IP_);
-	if (!atomic_inc_not_zero(&pag->pag_active_ref))
-		pag = NULL;
 	rcu_read_unlock();
 	return pag;
 }
@@ -1038,7 +1038,7 @@ xfs_reclaim_inodes(
 	if (xfs_want_reclaim_sick(mp))
 		icw.icw_flags |= XFS_ICWALK_FLAG_RECLAIM_SICK;
 
-	while (radix_tree_tagged(&mp->m_perag_tree, XFS_ICI_RECLAIM_TAG)) {
+	while (xa_marked(&mp->m_perags, XFS_PERAG_RECLAIM_MARK)) {
 		xfs_ail_push_all_sync(mp->m_ail);
 		xfs_icwalk(mp, XFS_ICWALK_RECLAIM, &icw);
 	}
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index d0567dfbc0368d..dce2d832e1e6d1 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -208,8 +208,7 @@ typedef struct xfs_mount {
 	 */
 	atomic64_t		m_allocbt_blks;
 
-	struct radix_tree_root	m_perag_tree;	/* per-ag accounting info */
-	spinlock_t		m_perag_lock;	/* lock for m_perag_tree */
+	struct xarray		m_perags;	/* per-ag accounting info */
 	uint64_t		m_resblks;	/* total reserved blocks */
 	uint64_t		m_resblks_avail;/* available reserved blocks */
 	uint64_t		m_resblks_save;	/* reserved blks @ remount,ro */
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 27e9f749c4c7fc..c41b543f2e9121 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -2009,8 +2009,7 @@ static int xfs_init_fs_context(
 		return -ENOMEM;
 
 	spin_lock_init(&mp->m_sb_lock);
-	INIT_RADIX_TREE(&mp->m_perag_tree, GFP_ATOMIC);
-	spin_lock_init(&mp->m_perag_lock);
+	xa_init(&mp->m_perags);
 	mutex_init(&mp->m_growlock);
 	INIT_WORK(&mp->m_flush_inodes_work, xfs_flush_inodes_worker);
 	INIT_DELAYED_WORK(&mp->m_reclaim_work, xfs_reclaim_worker);
-- 
2.43.0

[PATCH 5/5] xfs: use xas_for_each_marked in xfs_reclaim_inodes_count

[Christoph Hellwig]

xfs_reclaim_inodes_count iterates over all AGs to sum up the reclaimable
inodes counts.  There is no point in grabbing a reference to the them or
unlock the RCU critical section for each iteration, so switch to the
more efficient xas_for_each_marked iterator.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/xfs_icache.c | 36 ++++++++----------------------------
 fs/xfs/xfs_trace.h  |  2 +-
 2 files changed, 9 insertions(+), 29 deletions(-)

diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index 7ee32056897d58..d36dbaba660013 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -300,32 +300,6 @@ xfs_perag_clear_inode_tag(
 	trace_xfs_perag_clear_inode_tag(pag, _RET_IP_);
 }
 
-/*
- * Find the next AG after @pag, or the first AG if @pag is NULL.
- */
-static struct xfs_perag *
-xfs_perag_get_next_tag(
-	struct xfs_mount	*mp,
-	struct xfs_perag	*pag,
-	unsigned int		tag)
-{
-	unsigned long		index = 0;
-
-	if (pag) {
-		index = pag->pag_agno + 1;
-		xfs_perag_rele(pag);
-	}
-
-	rcu_read_lock();
-	pag = xa_find(&mp->m_perags, &index, ULONG_MAX, ici_tag_to_mark(tag));
-	if (pag) {
-		trace_xfs_perag_get_next_tag(pag, _RET_IP_);
-		atomic_inc(&pag->pag_ref);
-	}
-	rcu_read_unlock();
-	return pag;
-}
-
 /*
  * Find the next AG after @pag, or the first AG if @pag is NULL.
  */
@@ -1080,11 +1054,17 @@ long
 xfs_reclaim_inodes_count(
 	struct xfs_mount	*mp)
 {
-	struct xfs_perag	*pag = NULL;
+	XA_STATE		(xas, &mp->m_perags, 0);
 	long			reclaimable = 0;
+	struct xfs_perag	*pag;
 
-	while ((pag = xfs_perag_get_next_tag(mp, pag, XFS_ICI_RECLAIM_TAG)))
+	rcu_read_lock();
+	xas_for_each_marked(&xas, pag, ULONG_MAX, XFS_PERAG_RECLAIM_MARK) {
+		trace_xfs_reclaim_inodes_count(pag, _THIS_IP_);
 		reclaimable += pag->pag_ici_reclaimable;
+	}
+	rcu_read_unlock();
+
 	return reclaimable;
 }
 
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index 002d012ebd83cb..d73c0a49d9dc29 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -210,7 +210,6 @@ DEFINE_EVENT(xfs_perag_class, name,	\
 	TP_PROTO(struct xfs_perag *pag, unsigned long caller_ip), \
 	TP_ARGS(pag, caller_ip))
 DEFINE_PERAG_REF_EVENT(xfs_perag_get);
-DEFINE_PERAG_REF_EVENT(xfs_perag_get_next_tag);
 DEFINE_PERAG_REF_EVENT(xfs_perag_hold);
 DEFINE_PERAG_REF_EVENT(xfs_perag_put);
 DEFINE_PERAG_REF_EVENT(xfs_perag_grab);
@@ -218,6 +217,7 @@ DEFINE_PERAG_REF_EVENT(xfs_perag_grab_next_tag);
 DEFINE_PERAG_REF_EVENT(xfs_perag_rele);
 DEFINE_PERAG_REF_EVENT(xfs_perag_set_inode_tag);
 DEFINE_PERAG_REF_EVENT(xfs_perag_clear_inode_tag);
+DEFINE_PERAG_REF_EVENT(xfs_reclaim_inodes_count);
 
 TRACE_EVENT(xfs_inodegc_worker,
 	TP_PROTO(struct xfs_mount *mp, unsigned int shrinker_hits),
-- 
2.43.0

Re: [PATCH 1/5] xfs: use kfree_rcu_mightsleep to free the perag structures

[Darrick J. Wong]

On Thu, Aug 29, 2024 at 07:08:37AM +0300, Christoph Hellwig wrote:
> Using the kfree_rcu_mightsleep is simpler and removes the need for a
> rcu_head in the perag structure.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Looks good to me!
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
>  fs/xfs/libxfs/xfs_ag.c | 12 +-----------
>  fs/xfs/libxfs/xfs_ag.h |  3 ---
>  2 files changed, 1 insertion(+), 14 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_ag.c b/fs/xfs/libxfs/xfs_ag.c
> index 7e80732cb54708..4b5a39a83f7aed 100644
> --- a/fs/xfs/libxfs/xfs_ag.c
> +++ b/fs/xfs/libxfs/xfs_ag.c
> @@ -235,16 +235,6 @@ xfs_initialize_perag_data(
>  	return error;
>  }
>  
> -STATIC void
> -__xfs_free_perag(
> -	struct rcu_head	*head)
> -{
> -	struct xfs_perag *pag = container_of(head, struct xfs_perag, rcu_head);
> -
> -	ASSERT(!delayed_work_pending(&pag->pag_blockgc_work));
> -	kfree(pag);
> -}
> -
>  /*
>   * Free up the per-ag resources associated with the mount structure.
>   */
> @@ -270,7 +260,7 @@ xfs_free_perag(
>  		xfs_perag_rele(pag);
>  		XFS_IS_CORRUPT(pag->pag_mount,
>  				atomic_read(&pag->pag_active_ref) != 0);
> -		call_rcu(&pag->rcu_head, __xfs_free_perag);
> +		kfree_rcu_mightsleep(pag);
>  	}
>  }
>  
> diff --git a/fs/xfs/libxfs/xfs_ag.h b/fs/xfs/libxfs/xfs_ag.h
> index 35de09a2516c70..d62c266c0b44d5 100644
> --- a/fs/xfs/libxfs/xfs_ag.h
> +++ b/fs/xfs/libxfs/xfs_ag.h
> @@ -63,9 +63,6 @@ struct xfs_perag {
>  	/* Blocks reserved for the reverse mapping btree. */
>  	struct xfs_ag_resv	pag_rmapbt_resv;
>  
> -	/* for rcu-safe freeing */
> -	struct rcu_head	rcu_head;
> -
>  	/* Precalculated geometry info */
>  	xfs_agblock_t		block_count;
>  	xfs_agblock_t		min_block;
> -- 
> 2.43.0
> 
> 

Re: [PATCH 3/5] xfs: simplify tagged perag iteration

[Darrick J. Wong]

On Thu, Aug 29, 2024 at 07:08:39AM +0300, Christoph Hellwig wrote:
> Pass the old perag structure to the tagged loop helpers so that they can
> grab the old agno before releasing the reference.  This removes the need
> to separately track the agno and the iterator macro, and thus also
> obsoletes the for_each_perag_tag syntactic sugar.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

I like this change!
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
>  fs/xfs/xfs_icache.c | 71 +++++++++++++++++++++------------------------
>  fs/xfs/xfs_trace.h  |  4 +--
>  2 files changed, 35 insertions(+), 40 deletions(-)
> 
> diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
> index ac604640d36229..573743b1841fe7 100644
> --- a/fs/xfs/xfs_icache.c
> +++ b/fs/xfs/xfs_icache.c
> @@ -293,63 +293,66 @@ xfs_perag_clear_inode_tag(
>  }
>  
>  /*
> - * Search from @first to find the next perag with the given tag set.
> + * Find the next AG after @pag, or the first AG if @pag is NULL.
>   */
>  static struct xfs_perag *
> -xfs_perag_get_tag(
> +xfs_perag_get_next_tag(
>  	struct xfs_mount	*mp,
> -	xfs_agnumber_t		first,
> +	struct xfs_perag	*pag,
>  	unsigned int		tag)
>  {
> -	struct xfs_perag	*pag;
> +	unsigned long		index = 0;
>  	int			found;
>  
> +	if (pag) {
> +		index = pag->pag_agno + 1;
> +		xfs_perag_rele(pag);
> +	}
> +
>  	rcu_read_lock();
>  	found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
> -					(void **)&pag, first, 1, tag);
> +					(void **)&pag, index, 1, tag);
>  	if (found <= 0) {
>  		rcu_read_unlock();
>  		return NULL;
>  	}
> -	trace_xfs_perag_get_tag(pag, _RET_IP_);
> +	trace_xfs_perag_get_next_tag(pag, _RET_IP_);
>  	atomic_inc(&pag->pag_ref);
>  	rcu_read_unlock();
>  	return pag;
>  }
>  
>  /*
> - * Search from @first to find the next perag with the given tag set.
> + * Find the next AG after @pag, or the first AG if @pag is NULL.
>   */
>  static struct xfs_perag *
> -xfs_perag_grab_tag(
> +xfs_perag_grab_next_tag(
>  	struct xfs_mount	*mp,
> -	xfs_agnumber_t		first,
> +	struct xfs_perag	*pag,
>  	int			tag)
>  {
> -	struct xfs_perag	*pag;
> +	unsigned long		index = 0;
>  	int			found;
>  
> +	if (pag) {
> +		index = pag->pag_agno + 1;
> +		xfs_perag_rele(pag);
> +	}
> +
>  	rcu_read_lock();
>  	found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
> -					(void **)&pag, first, 1, tag);
> +					(void **)&pag, index, 1, tag);
>  	if (found <= 0) {
>  		rcu_read_unlock();
>  		return NULL;
>  	}
> -	trace_xfs_perag_grab_tag(pag, _RET_IP_);
> +	trace_xfs_perag_grab_next_tag(pag, _RET_IP_);
>  	if (!atomic_inc_not_zero(&pag->pag_active_ref))
>  		pag = NULL;
>  	rcu_read_unlock();
>  	return pag;
>  }
>  
> -#define for_each_perag_tag(mp, agno, pag, tag) \
> -	for ((agno) = 0, (pag) = xfs_perag_grab_tag((mp), 0, (tag)); \
> -		(pag) != NULL; \
> -		(agno) = (pag)->pag_agno + 1, \
> -		xfs_perag_rele(pag), \
> -		(pag) = xfs_perag_grab_tag((mp), (agno), (tag)))
> -
>  /*
>   * When we recycle a reclaimable inode, we need to re-initialise the VFS inode
>   * part of the structure. This is made more complex by the fact we store
> @@ -1077,15 +1080,11 @@ long
>  xfs_reclaim_inodes_count(
>  	struct xfs_mount	*mp)
>  {
> -	struct xfs_perag	*pag;
> -	xfs_agnumber_t		ag = 0;
> +	struct xfs_perag	*pag = NULL;
>  	long			reclaimable = 0;
>  
> -	while ((pag = xfs_perag_get_tag(mp, ag, XFS_ICI_RECLAIM_TAG))) {
> -		ag = pag->pag_agno + 1;
> +	while ((pag = xfs_perag_get_next_tag(mp, pag, XFS_ICI_RECLAIM_TAG)))
>  		reclaimable += pag->pag_ici_reclaimable;
> -		xfs_perag_put(pag);
> -	}
>  	return reclaimable;
>  }
>  
> @@ -1427,14 +1426,13 @@ void
>  xfs_blockgc_start(
>  	struct xfs_mount	*mp)
>  {
> -	struct xfs_perag	*pag;
> -	xfs_agnumber_t		agno;
> +	struct xfs_perag	*pag = NULL;
>  
>  	if (xfs_set_blockgc_enabled(mp))
>  		return;
>  
>  	trace_xfs_blockgc_start(mp, __return_address);
> -	for_each_perag_tag(mp, agno, pag, XFS_ICI_BLOCKGC_TAG)
> +	while ((pag = xfs_perag_grab_next_tag(mp, pag, XFS_ICI_BLOCKGC_TAG)))
>  		xfs_blockgc_queue(pag);
>  }
>  
> @@ -1550,21 +1548,19 @@ int
>  xfs_blockgc_flush_all(
>  	struct xfs_mount	*mp)
>  {
> -	struct xfs_perag	*pag;
> -	xfs_agnumber_t		agno;
> +	struct xfs_perag	*pag = NULL;
>  
>  	trace_xfs_blockgc_flush_all(mp, __return_address);
>  
>  	/*
> -	 * For each blockgc worker, move its queue time up to now.  If it
> -	 * wasn't queued, it will not be requeued.  Then flush whatever's
> -	 * left.
> +	 * For each blockgc worker, move its queue time up to now.  If it wasn't
> +	 * queued, it will not be requeued.  Then flush whatever is left.
>  	 */
> -	for_each_perag_tag(mp, agno, pag, XFS_ICI_BLOCKGC_TAG)
> +	while ((pag = xfs_perag_grab_next_tag(mp, pag, XFS_ICI_BLOCKGC_TAG)))
>  		mod_delayed_work(pag->pag_mount->m_blockgc_wq,
>  				&pag->pag_blockgc_work, 0);
>  
> -	for_each_perag_tag(mp, agno, pag, XFS_ICI_BLOCKGC_TAG)
> +	while ((pag = xfs_perag_grab_next_tag(mp, pag, XFS_ICI_BLOCKGC_TAG)))
>  		flush_delayed_work(&pag->pag_blockgc_work);
>  
>  	return xfs_inodegc_flush(mp);
> @@ -1810,12 +1806,11 @@ xfs_icwalk(
>  	enum xfs_icwalk_goal	goal,
>  	struct xfs_icwalk	*icw)
>  {
> -	struct xfs_perag	*pag;
> +	struct xfs_perag	*pag = NULL;
>  	int			error = 0;
>  	int			last_error = 0;
> -	xfs_agnumber_t		agno;
>  
> -	for_each_perag_tag(mp, agno, pag, goal) {
> +	while ((pag = xfs_perag_grab_next_tag(mp, pag, goal))) {
>  		error = xfs_icwalk_ag(pag, goal, icw);
>  		if (error) {
>  			last_error = error;
> diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
> index 180ce697305a92..002d012ebd83cb 100644
> --- a/fs/xfs/xfs_trace.h
> +++ b/fs/xfs/xfs_trace.h
> @@ -210,11 +210,11 @@ DEFINE_EVENT(xfs_perag_class, name,	\
>  	TP_PROTO(struct xfs_perag *pag, unsigned long caller_ip), \
>  	TP_ARGS(pag, caller_ip))
>  DEFINE_PERAG_REF_EVENT(xfs_perag_get);
> -DEFINE_PERAG_REF_EVENT(xfs_perag_get_tag);
> +DEFINE_PERAG_REF_EVENT(xfs_perag_get_next_tag);
>  DEFINE_PERAG_REF_EVENT(xfs_perag_hold);
>  DEFINE_PERAG_REF_EVENT(xfs_perag_put);
>  DEFINE_PERAG_REF_EVENT(xfs_perag_grab);
> -DEFINE_PERAG_REF_EVENT(xfs_perag_grab_tag);
> +DEFINE_PERAG_REF_EVENT(xfs_perag_grab_next_tag);
>  DEFINE_PERAG_REF_EVENT(xfs_perag_rele);
>  DEFINE_PERAG_REF_EVENT(xfs_perag_set_inode_tag);
>  DEFINE_PERAG_REF_EVENT(xfs_perag_clear_inode_tag);
> -- 
> 2.43.0
> 
> 

Re: [PATCH 2/5] xfs: move the tagged perag lookup helpers to xfs_icache.c

[Darrick J. Wong]

On Thu, Aug 29, 2024 at 07:08:38AM +0300, Christoph Hellwig wrote:
> The tagged perag helpers are only used in xfs_icache.c in the kernel code
> and not at all in xfsprogs.  Move them to xfs_icache.c in preparation for
> switching to an xarray, for which I have no plan to implement the tagged
> lookup functions for userspace.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Not thrilled about this, but I won't hold up the rest of the
conversion...
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> ---
>  fs/xfs/libxfs/xfs_ag.c | 51 -------------------------------------
>  fs/xfs/libxfs/xfs_ag.h | 11 --------
>  fs/xfs/xfs_icache.c    | 58 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 58 insertions(+), 62 deletions(-)
> 
> diff --git a/fs/xfs/libxfs/xfs_ag.c b/fs/xfs/libxfs/xfs_ag.c
> index 4b5a39a83f7aed..87f00f0180846f 100644
> --- a/fs/xfs/libxfs/xfs_ag.c
> +++ b/fs/xfs/libxfs/xfs_ag.c
> @@ -56,31 +56,6 @@ xfs_perag_get(
>  	return pag;
>  }
>  
> -/*
> - * search from @first to find the next perag with the given tag set.
> - */
> -struct xfs_perag *
> -xfs_perag_get_tag(
> -	struct xfs_mount	*mp,
> -	xfs_agnumber_t		first,
> -	unsigned int		tag)
> -{
> -	struct xfs_perag	*pag;
> -	int			found;
> -
> -	rcu_read_lock();
> -	found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
> -					(void **)&pag, first, 1, tag);
> -	if (found <= 0) {
> -		rcu_read_unlock();
> -		return NULL;
> -	}
> -	trace_xfs_perag_get_tag(pag, _RET_IP_);
> -	atomic_inc(&pag->pag_ref);
> -	rcu_read_unlock();
> -	return pag;
> -}
> -
>  /* Get a passive reference to the given perag. */
>  struct xfs_perag *
>  xfs_perag_hold(
> @@ -127,32 +102,6 @@ xfs_perag_grab(
>  	return pag;
>  }
>  
> -/*
> - * search from @first to find the next perag with the given tag set.
> - */
> -struct xfs_perag *
> -xfs_perag_grab_tag(
> -	struct xfs_mount	*mp,
> -	xfs_agnumber_t		first,
> -	int			tag)
> -{
> -	struct xfs_perag	*pag;
> -	int			found;
> -
> -	rcu_read_lock();
> -	found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
> -					(void **)&pag, first, 1, tag);
> -	if (found <= 0) {
> -		rcu_read_unlock();
> -		return NULL;
> -	}
> -	trace_xfs_perag_grab_tag(pag, _RET_IP_);
> -	if (!atomic_inc_not_zero(&pag->pag_active_ref))
> -		pag = NULL;
> -	rcu_read_unlock();
> -	return pag;
> -}
> -
>  void
>  xfs_perag_rele(
>  	struct xfs_perag	*pag)
> diff --git a/fs/xfs/libxfs/xfs_ag.h b/fs/xfs/libxfs/xfs_ag.h
> index d62c266c0b44d5..d9cccd093b60e0 100644
> --- a/fs/xfs/libxfs/xfs_ag.h
> +++ b/fs/xfs/libxfs/xfs_ag.h
> @@ -153,15 +153,11 @@ void xfs_free_perag(struct xfs_mount *mp);
>  
>  /* Passive AG references */
>  struct xfs_perag *xfs_perag_get(struct xfs_mount *mp, xfs_agnumber_t agno);
> -struct xfs_perag *xfs_perag_get_tag(struct xfs_mount *mp, xfs_agnumber_t agno,
> -		unsigned int tag);
>  struct xfs_perag *xfs_perag_hold(struct xfs_perag *pag);
>  void xfs_perag_put(struct xfs_perag *pag);
>  
>  /* Active AG references */
>  struct xfs_perag *xfs_perag_grab(struct xfs_mount *, xfs_agnumber_t);
> -struct xfs_perag *xfs_perag_grab_tag(struct xfs_mount *, xfs_agnumber_t,
> -				   int tag);
>  void xfs_perag_rele(struct xfs_perag *pag);
>  
>  /*
> @@ -263,13 +259,6 @@ xfs_perag_next(
>  	(agno) = 0; \
>  	for_each_perag_from((mp), (agno), (pag))
>  
> -#define for_each_perag_tag(mp, agno, pag, tag) \
> -	for ((agno) = 0, (pag) = xfs_perag_grab_tag((mp), 0, (tag)); \
> -		(pag) != NULL; \
> -		(agno) = (pag)->pag_agno + 1, \
> -		xfs_perag_rele(pag), \
> -		(pag) = xfs_perag_grab_tag((mp), (agno), (tag)))
> -
>  static inline struct xfs_perag *
>  xfs_perag_next_wrap(
>  	struct xfs_perag	*pag,
> diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
> index cf629302d48e74..ac604640d36229 100644
> --- a/fs/xfs/xfs_icache.c
> +++ b/fs/xfs/xfs_icache.c
> @@ -292,6 +292,64 @@ xfs_perag_clear_inode_tag(
>  	trace_xfs_perag_clear_inode_tag(pag, _RET_IP_);
>  }
>  
> +/*
> + * Search from @first to find the next perag with the given tag set.
> + */
> +static struct xfs_perag *
> +xfs_perag_get_tag(
> +	struct xfs_mount	*mp,
> +	xfs_agnumber_t		first,
> +	unsigned int		tag)
> +{
> +	struct xfs_perag	*pag;
> +	int			found;
> +
> +	rcu_read_lock();
> +	found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
> +					(void **)&pag, first, 1, tag);
> +	if (found <= 0) {
> +		rcu_read_unlock();
> +		return NULL;
> +	}
> +	trace_xfs_perag_get_tag(pag, _RET_IP_);
> +	atomic_inc(&pag->pag_ref);
> +	rcu_read_unlock();
> +	return pag;
> +}
> +
> +/*
> + * Search from @first to find the next perag with the given tag set.
> + */
> +static struct xfs_perag *
> +xfs_perag_grab_tag(
> +	struct xfs_mount	*mp,
> +	xfs_agnumber_t		first,
> +	int			tag)
> +{
> +	struct xfs_perag	*pag;
> +	int			found;
> +
> +	rcu_read_lock();
> +	found = radix_tree_gang_lookup_tag(&mp->m_perag_tree,
> +					(void **)&pag, first, 1, tag);
> +	if (found <= 0) {
> +		rcu_read_unlock();
> +		return NULL;
> +	}
> +	trace_xfs_perag_grab_tag(pag, _RET_IP_);
> +	if (!atomic_inc_not_zero(&pag->pag_active_ref))
> +		pag = NULL;
> +	rcu_read_unlock();
> +	return pag;
> +}
> +
> +#define for_each_perag_tag(mp, agno, pag, tag) \
> +	for ((agno) = 0, (pag) = xfs_perag_grab_tag((mp), 0, (tag)); \
> +		(pag) != NULL; \
> +		(agno) = (pag)->pag_agno + 1, \
> +		xfs_perag_rele(pag), \
> +		(pag) = xfs_perag_grab_tag((mp), (agno), (tag)))
> +
>  /*
>   * When we recycle a reclaimable inode, we need to re-initialise the VFS inode
>   * part of the structure. This is made more complex by the fact we store
> -- 
> 2.43.0
> 
>