[PATCH 36/52] fuse: Kick worker when free memory drops below 20% of total ranges

[Vivek Goyal <vgoyal@xxxxxxxxxx>]

Kick worker to free up some memory when number of free ranges drops below
20% of total free ranges at the time of initialization.

Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
---
 fs/fuse/file.c   | 11 ++++++++++-
 fs/fuse/fuse_i.h |  9 +++++++++
 fs/fuse/inode.c  |  1 +
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 13db83d105ff..1f172d372eeb 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -186,6 +186,7 @@ static void fuse_link_write_file(struct file *file)
 
 static struct fuse_dax_mapping *alloc_dax_mapping(struct fuse_conn *fc)
 {
+	unsigned long free_threshold;
 	struct fuse_dax_mapping *dmap = NULL;
 
 	spin_lock(&fc->lock);
@@ -193,7 +194,7 @@ static struct fuse_dax_mapping *alloc_dax_mapping(struct fuse_conn *fc)
 	/* TODO: Add logic to try to free up memory if wait is allowed */
 	if (fc->nr_free_ranges <= 0) {
 		spin_unlock(&fc->lock);
-		return NULL;
+		goto out_kick;
 	}
 
 	WARN_ON(list_empty(&fc->free_ranges));
@@ -204,6 +205,14 @@ static struct fuse_dax_mapping *alloc_dax_mapping(struct fuse_conn *fc)
 	list_del_init(&dmap->list);
 	fc->nr_free_ranges--;
 	spin_unlock(&fc->lock);
+
+out_kick:
+	/* If number of free ranges are below threshold, start reclaim */
+	free_threshold = (fc->nr_ranges * FUSE_DAX_RECLAIM_THRESHOLD)/100;
+	if (free_threshold > 0 && fc->nr_free_ranges < free_threshold) {
+		pr_debug("fuse: Kicking dax memory reclaim worker. nr_free_ranges=0x%ld nr_total_ranges=%ld\n", fc->nr_free_ranges, fc->nr_ranges);
+		queue_delayed_work(system_long_wq, &fc->dax_free_work, 0);
+	}
 	return dmap;
 }
 
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 383deaf0ecf1..bbefa7c11078 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -53,6 +53,13 @@
 /* Number of ranges reclaimer will try to free in one invocation */
 #define FUSE_DAX_RECLAIM_CHUNK		(10)
 
+/*
+ * Dax memory reclaim threshold in percetage of total ranges. When free
+ * number of free ranges drops below this threshold, reclaim can trigger
+ * Default is 20%
+ * */
+#define FUSE_DAX_RECLAIM_THRESHOLD	(20)
+
 /** List of active connections */
 extern struct list_head fuse_conn_list;
 
@@ -885,6 +892,8 @@ struct fuse_conn {
 	 */
 	unsigned long nr_free_ranges;
 	struct list_head free_ranges;
+
+	unsigned long nr_ranges;
 };
 
 static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 44f7bc44e319..d31acb97eede 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -675,6 +675,7 @@ static int fuse_dax_mem_range_init(struct fuse_conn *fc,
 
 	list_replace_init(&mem_ranges, &fc->free_ranges);
 	fc->nr_free_ranges = allocated_ranges;
+	fc->nr_ranges = allocated_ranges;
 	return 0;
 out_err:
 	/* Free All allocated elements */
-- 
2.13.6