[PATCH 17/20] fuse,virtiofs: 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   | 22 ++++++++++++++++++++++
 fs/fuse/fuse_i.h |  8 ++++++++
 fs/fuse/inode.c  |  4 ++++
 3 files changed, 34 insertions(+)

diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 619aff6b5f44..afabeb1acd50 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -215,6 +215,23 @@ static struct fuse_dax_mapping *alloc_dax_mapping(struct 
fuse_conn *fc)
        return dmap;
 }
 
+/* This assumes fc->lock is held */
+static void __dmap_remove_busy_list(struct fuse_conn *fc,
+                                   struct fuse_dax_mapping *dmap)
+{
+       list_del_init(&dmap->busy_list);
+       WARN_ON(fc->nr_busy_ranges == 0);
+       fc->nr_busy_ranges--;
+}
+
+static void dmap_remove_busy_list(struct fuse_conn *fc,
+                                 struct fuse_dax_mapping *dmap)
+{
+       spin_lock(&fc->lock);
+       __dmap_remove_busy_list(fc, dmap);
+       spin_unlock(&fc->lock);
+}
+
 /* This assumes fc->lock is held */
 static void __dmap_add_to_free_pool(struct fuse_conn *fc,
                                struct fuse_dax_mapping *dmap)
@@ -277,6 +294,10 @@ static int fuse_setup_one_mapping(struct inode *inode, 
loff_t offset,
                /* 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;
 }
@@ -346,6 +367,7 @@ static void dmap_reinit_add_to_free_pool(struct fuse_conn 
*fc,
        pr_debug("fuse: freeing memory range start=0x%llx end=0x%llx "
                 "window_offset=0x%llx length=0x%llx\n", dmap->start,
                 dmap->end, dmap->window_offset, dmap->length);
+       __dmap_remove_busy_list(fc, dmap);
        dmap->start = dmap->end = 0;
        __dmap_add_to_free_pool(fc, dmap);
 }
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 3fea84411401..de213a7e1b0e 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -85,6 +85,10 @@ struct fuse_dax_mapping {
        /** End Position in file */
        __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;
 
@@ -814,6 +818,10 @@ 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
         */
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index abc881e6acb0..d4770e7fb7eb 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -616,6 +616,8 @@ 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);
        }
 }
@@ -660,6 +662,7 @@ 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);
        }
 
@@ -707,6 +710,7 @@ 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
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