[PATCH 2/3] ocfs2: adjust enabling place for la window

From: Heming Zhao <heming.zhao@suse.com>
To: joseph.qi@linux.alibaba.com
Cc: Heming Zhao <heming.zhao@suse.com>,
	ocfs2-devel@lists.linux.dev, ailiop@suse.com
Subject: [PATCH 2/3] ocfs2: adjust enabling place for la window
Date: Wed, 27 Mar 2024 14:09:13 +0800	[thread overview]
Message-ID: <20240327060914.2583-3-heming.zhao@suse.com> (raw)
In-Reply-To: <20240327060914.2583-1-heming.zhao@suse.com>

After introducing gd->bg_contig_free_bits, the code path
'ocfs2_cluster_group_search() => ocfs2_local_alloc_seen_free_bits()'
becomes death when all the gd->bg_contig_free_bits are set to the
correct value. This patch relocates ocfs2_local_alloc_seen_free_bits()
to a more appropriate location. (The new place being
ocfs2_block_group_set_bits().)

In ocfs2_local_alloc_seen_free_bits(), the scope of the spin-lock has
been adjusted to reduce meaningless lock races. e.g: when userspace
creates & deletes 1 cluster_size files in parallel, acquiring the
spin-lock in ocfs2_local_alloc_seen_free_bits() is totally pointless and
impedes IO performance.

Signed-off-by: Heming Zhao <heming.zhao@suse.com>
---
 fs/ocfs2/localalloc.c | 15 ++++++++-------
 fs/ocfs2/suballoc.c   |  9 ++-------
 2 files changed, 10 insertions(+), 14 deletions(-)

diff --git a/fs/ocfs2/localalloc.c b/fs/ocfs2/localalloc.c
index c803c10dd97e..2391b96b8a3b 100644
--- a/fs/ocfs2/localalloc.c
+++ b/fs/ocfs2/localalloc.c
@@ -212,14 +212,15 @@ static inline int ocfs2_la_state_enabled(struct ocfs2_super *osb)
 void ocfs2_local_alloc_seen_free_bits(struct ocfs2_super *osb,
 				      unsigned int num_clusters)
 {
-	spin_lock(&osb->osb_lock);
-	if (osb->local_alloc_state == OCFS2_LA_DISABLED ||
-	    osb->local_alloc_state == OCFS2_LA_THROTTLED)
-		if (num_clusters >= osb->local_alloc_default_bits) {
+	if (num_clusters >= osb->local_alloc_default_bits) {
+		spin_lock(&osb->osb_lock);
+		if (osb->local_alloc_state == OCFS2_LA_DISABLED ||
+		    osb->local_alloc_state == OCFS2_LA_THROTTLED)
 			cancel_delayed_work(&osb->la_enable_wq);
-			osb->local_alloc_state = OCFS2_LA_ENABLED;
-		}
-	spin_unlock(&osb->osb_lock);
+
+		osb->local_alloc_state = OCFS2_LA_ENABLED;
+		spin_unlock(&osb->osb_lock);
+	}
 }
 
 void ocfs2_la_enable_worker(struct work_struct *work)
diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c
index 6fd67c8da9fe..4163554b0383 100644
--- a/fs/ocfs2/suballoc.c
+++ b/fs/ocfs2/suballoc.c
@@ -1374,6 +1374,7 @@ int ocfs2_block_group_set_bits(handle_t *handle,
 	int journal_type = OCFS2_JOURNAL_ACCESS_WRITE;
 	unsigned int start = bit_off + num_bits;
 	u16 contig_bits;
+	struct ocfs2_super *osb = OCFS2_SB(alloc_inode->i_sb);
 
 	/* All callers get the descriptor via
 	 * ocfs2_read_group_descriptor().  Any corruption is a code bug. */
@@ -1423,6 +1424,7 @@ int ocfs2_block_group_set_bits(handle_t *handle,
 		if (contig_bits > max_contig_bits)
 			max_contig_bits = contig_bits;
 		bg->bg_contig_free_bits = cpu_to_le16(max_contig_bits);
+		ocfs2_local_alloc_seen_free_bits(osb, max_contig_bits);
 	} else {
 		bg->bg_contig_free_bits = 0;
 	}
@@ -1589,13 +1591,6 @@ static int ocfs2_cluster_group_search(struct inode *inode,
 		 * of bits. */
 		if (min_bits <= res->sr_bits)
 			search = 0; /* success */
-		else if (res->sr_bits) {
-			/*
-			 * Don't show bits which we'll be returning
-			 * for allocation to the local alloc bitmap.
-			 */
-			ocfs2_local_alloc_seen_free_bits(osb, res->sr_bits);
-		}
 	}
 
 	return search;
-- 
2.35.3

