[PATCH v2 25/30] fuse: Maintain a list of busy elements

[Vivek Goyal]

This list will be used selecting fuse_dax_mapping to free when number of
free mappings drops below a threshold.

Signed-off-by: Vivek Goyal <vgo...@redhat.com>
---
 fs/fuse/file.c   | 8 ++++++++
 fs/fuse/fuse_i.h | 7 +++++++
 fs/fuse/inode.c  | 4 ++++
 3 files changed, 19 insertions(+)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index e536a04aaa06..3f0f7a387341 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -273,6 +273,10 @@ static int fuse_setup_one_mapping(struct inode *inode,
        /* Protected by fi->i_dmap_sem */
        fuse_dax_interval_tree_insert(dmap, &fi->dmap_tree);
        fi->nr_dmaps++;
+       spin_lock(&fc->lock);
+       list_add_tail(&dmap->busy_list, &fc->busy_ranges);
+       fc->nr_busy_ranges++;
+       spin_unlock(&fc->lock);
        return 0;
 }
 
@@ -317,6 +321,10 @@ void fuse_removemapping(struct inode *inode)
                if (dmap) {
                        fuse_dax_interval_tree_remove(dmap, &fi->dmap_tree);
                        fi->nr_dmaps--;
+                       spin_lock(&fc->lock);
+                       list_del_init(&dmap->busy_list);
+                       fc->nr_busy_ranges--;
+                       spin_unlock(&fc->lock);
                }
 
                if (!dmap)
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index a234cf30538d..c93e9155b723 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -114,6 +114,9 @@ struct fuse_dax_mapping {
        __u64 end;
        __u64 __subtree_last;
 
+       /* Will connect in fc->busy_ranges to keep track busy memory */
+       struct list_head busy_list;
+
        /** Position in DAX window */
        u64 window_offset;
 
@@ -873,6 +876,10 @@ struct fuse_conn {
        /** DAX device, non-NULL if DAX is supported */
        struct dax_device *dax_dev;
 
+       /* List of memory ranges which are busy */
+       unsigned long nr_busy_ranges;
+       struct list_head busy_ranges;
+
        /*
         * DAX Window Free Ranges. TODO: This might not be best place to store
         * this free list
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 713c5f32ab35..f57f7ce02acc 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -626,6 +626,8 @@ static void fuse_free_dax_mem_ranges(struct list_head 
*mem_list)
        /* Free All allocated elements */
        list_for_each_entry_safe(range, temp, mem_list, list) {
                list_del(&range->list);
+               if (!list_empty(&range->busy_list))
+                       list_del(&range->busy_list);
                kfree(range);
        }
 }
@@ -670,6 +672,7 @@ static int fuse_dax_mem_range_init(struct fuse_conn *fc,
                 */
                range->window_offset = i * FUSE_DAX_MEM_RANGE_SZ;
                range->length = FUSE_DAX_MEM_RANGE_SZ;
+               INIT_LIST_HEAD(&range->busy_list);
                list_add_tail(&range->list, &mem_ranges);
        }
 
@@ -720,6 +723,7 @@ void fuse_conn_init(struct fuse_conn *fc, struct 
user_namespace *user_ns,
        fc->user_ns = get_user_ns(user_ns);
        fc->max_pages = FUSE_DEFAULT_MAX_PAGES_PER_REQ;
        INIT_LIST_HEAD(&fc->free_ranges);
+       INIT_LIST_HEAD(&fc->busy_ranges);
 }
 EXPORT_SYMBOL_GPL(fuse_conn_init);
 
-- 
2.20.1