virtiofs: maintain a list of busy elements

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 <vgoyal@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/fs/fuse/dax.c b/fs/fuse/dax.c
index efc1a8e..e640783 100644 (file)
--- a/fs/fuse/dax.c
+++ b/fs/fuse/dax.c
@@ -28,6 +28,9 @@ struct fuse_dax_mapping {
        /* For interval tree in file/inode */
        struct interval_tree_node itn;
 
+       /* Will connect in fc->busy_ranges to keep track busy memory */
+       struct list_head busy_list;
+
        /** Position in DAX window */
        u64 window_offset;
 
@@ -55,6 +58,10 @@ struct fuse_conn_dax {
        /* Lock protecting accessess to  members of this structure */
        spinlock_t lock;
 
+       /* List of memory ranges which are busy */
+       unsigned long nr_busy_ranges;
+       struct list_head busy_ranges;
+
        /* DAX Window Free Ranges */
        long nr_free_ranges;
        struct list_head free_ranges;
@@ -85,6 +92,15 @@ static struct fuse_dax_mapping *alloc_dax_mapping(struct fuse_conn_dax *fcd)
        return dmap;
 }
 
+/* This assumes fcd->lock is held */
+static void __dmap_remove_busy_list(struct fuse_conn_dax *fcd,
+                                   struct fuse_dax_mapping *dmap)
+{
+       list_del_init(&dmap->busy_list);
+       WARN_ON(fcd->nr_busy_ranges == 0);
+       fcd->nr_busy_ranges--;
+}
+
 /* This assumes fcd->lock is held */
 static void __dmap_add_to_free_pool(struct fuse_conn_dax *fcd,
                                struct fuse_dax_mapping *dmap)
@@ -139,6 +155,10 @@ static int fuse_setup_one_mapping(struct inode *inode, unsigned long start_idx,
                /* Protected by fi->dax->sem */
                interval_tree_insert(&dmap->itn, &fi->dax->tree);
                fi->dax->nr++;
+               spin_lock(&fcd->lock);
+               list_add_tail(&dmap->busy_list, &fcd->busy_ranges);
+               fcd->nr_busy_ranges++;
+               spin_unlock(&fcd->lock);
        }
        return 0;
 }
@@ -207,6 +227,7 @@ static void dmap_reinit_add_to_free_pool(struct fuse_conn_dax *fcd,
        pr_debug("fuse: freeing memory range start_idx=0x%lx end_idx=0x%lx window_offset=0x%llx length=0x%llx\n",
                 dmap->itn.start, dmap->itn.last, dmap->window_offset,
                 dmap->length);
+       __dmap_remove_busy_list(fcd, dmap);
        dmap->itn.start = dmap->itn.last = 0;
        __dmap_add_to_free_pool(fcd, dmap);
 }
@@ -700,6 +721,8 @@ 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);
        }
 }
@@ -723,6 +746,7 @@ static int fuse_dax_mem_range_init(struct fuse_conn_dax *fcd)
        unsigned long i;
 
        INIT_LIST_HEAD(&fcd->free_ranges);
+       INIT_LIST_HEAD(&fcd->busy_ranges);
        id = dax_read_lock();
        nr_pages = dax_direct_access(fcd->dev, 0, PHYS_PFN(dax_size), &kaddr,
                                     &pfn);
@@ -748,6 +772,7 @@ static int fuse_dax_mem_range_init(struct fuse_conn_dax *fcd)
                 */
                range->window_offset = i * FUSE_DAX_SZ;
                range->length = FUSE_DAX_SZ;
+               INIT_LIST_HEAD(&range->busy_list);
                list_add_tail(&range->list, &fcd->free_ranges);
        }