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Subject[PATCH v2 19/30] fuse: Keep a list of free dax memory ranges
Date
Divide the dax memory range into fixed size ranges (2MB for now) and put
them in a list. This will track free ranges. Once an inode requires a
free range, we will take one from here and put it in interval-tree
of ranges assigned to inode.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Peng Tao <tao.peng@linux.alibaba.com>
---
fs/fuse/fuse_i.h | 23 ++++++++++++
fs/fuse/inode.c | 86 +++++++++++++++++++++++++++++++++++++++++++++
fs/fuse/virtio_fs.c | 2 ++
3 files changed, 111 insertions(+)

diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 840c88af711c..5439e4628362 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -46,6 +46,10 @@
/** Number of page pointers embedded in fuse_req */
#define FUSE_REQ_INLINE_PAGES 1

+/* Default memory range size, 2MB */
+#define FUSE_DAX_MEM_RANGE_SZ (2*1024*1024)
+#define FUSE_DAX_MEM_RANGE_PAGES (FUSE_DAX_MEM_RANGE_SZ/PAGE_SIZE)
+
/** List of active connections */
extern struct list_head fuse_conn_list;

@@ -94,6 +98,18 @@ struct fuse_forget_link {
struct fuse_forget_link *next;
};

+/** Translation information for file offsets to DAX window offsets */
+struct fuse_dax_mapping {
+ /* Will connect in fc->free_ranges to keep track of free memory */
+ struct list_head list;
+
+ /** Position in DAX window */
+ u64 window_offset;
+
+ /** Length of mapping, in bytes */
+ loff_t length;
+};
+
/** FUSE inode */
struct fuse_inode {
/** Inode data */
@@ -829,6 +845,13 @@ struct fuse_conn {

/** DAX device, non-NULL if DAX is supported */
struct dax_device *dax_dev;
+
+ /*
+ * DAX Window Free Ranges. TODO: This might not be best place to store
+ * this free list
+ */
+ long nr_free_ranges;
+ struct list_head free_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 97d218a7daa8..8a3dd72f9843 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -22,6 +22,8 @@
#include <linux/exportfs.h>
#include <linux/posix_acl.h>
#include <linux/pid_namespace.h>
+#include <linux/dax.h>
+#include <linux/pfn_t.h>

MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
MODULE_DESCRIPTION("Filesystem in Userspace");
@@ -610,6 +612,76 @@ static void fuse_pqueue_init(struct fuse_pqueue *fpq)
fpq->connected = 1;
}

+static void fuse_free_dax_mem_ranges(struct list_head *mem_list)
+{
+ struct fuse_dax_mapping *range, *temp;
+
+ /* Free All allocated elements */
+ list_for_each_entry_safe(range, temp, mem_list, list) {
+ list_del(&range->list);
+ kfree(range);
+ }
+}
+
+#ifdef CONFIG_FS_DAX
+static int fuse_dax_mem_range_init(struct fuse_conn *fc,
+ struct dax_device *dax_dev)
+{
+ long nr_pages, nr_ranges;
+ void *kaddr;
+ pfn_t pfn;
+ struct fuse_dax_mapping *range;
+ LIST_HEAD(mem_ranges);
+ phys_addr_t phys_addr;
+ int ret = 0, id;
+ size_t dax_size = -1;
+ unsigned long i;
+
+ id = dax_read_lock();
+ nr_pages = dax_direct_access(dax_dev, 0, PHYS_PFN(dax_size), &kaddr,
+ &pfn);
+ dax_read_unlock(id);
+ if (nr_pages < 0) {
+ pr_debug("dax_direct_access() returned %ld\n", nr_pages);
+ return nr_pages;
+ }
+
+ phys_addr = pfn_t_to_phys(pfn);
+ nr_ranges = nr_pages/FUSE_DAX_MEM_RANGE_PAGES;
+ printk("fuse_dax_mem_range_init(): dax mapped %ld pages. nr_ranges=%ld\n", nr_pages, nr_ranges);
+
+ for (i = 0; i < nr_ranges; i++) {
+ range = kzalloc(sizeof(struct fuse_dax_mapping), GFP_KERNEL);
+ if (!range) {
+ pr_debug("memory allocation for mem_range failed.\n");
+ ret = -ENOMEM;
+ goto out_err;
+ }
+ /* TODO: This offset only works if virtio-fs driver is not
+ * having some memory hidden at the beginning. This needs
+ * better handling
+ */
+ range->window_offset = i * FUSE_DAX_MEM_RANGE_SZ;
+ range->length = FUSE_DAX_MEM_RANGE_SZ;
+ list_add_tail(&range->list, &mem_ranges);
+ }
+
+ list_replace_init(&mem_ranges, &fc->free_ranges);
+ fc->nr_free_ranges = nr_ranges;
+ return 0;
+out_err:
+ /* Free All allocated elements */
+ fuse_free_dax_mem_ranges(&mem_ranges);
+ return ret;
+}
+#else /* !CONFIG_FS_DAX */
+static inline int fuse_dax_mem_range_init(struct fuse_conn *fc,
+ struct dax_device *dax_dev)
+{
+ return 0;
+}
+#endif /* CONFIG_FS_DAX */
+
void fuse_conn_init(struct fuse_conn *fc, struct user_namespace *user_ns,
struct dax_device *dax_dev,
const struct fuse_iqueue_ops *fiq_ops, void *fiq_priv)
@@ -640,6 +712,7 @@ void fuse_conn_init(struct fuse_conn *fc, struct user_namespace *user_ns,
fc->dax_dev = dax_dev;
fc->user_ns = get_user_ns(user_ns);
fc->max_pages = FUSE_DEFAULT_MAX_PAGES_PER_REQ;
+ INIT_LIST_HEAD(&fc->free_ranges);
}
EXPORT_SYMBOL_GPL(fuse_conn_init);

@@ -648,6 +721,8 @@ void fuse_conn_put(struct fuse_conn *fc)
if (refcount_dec_and_test(&fc->count)) {
if (fc->destroy_req)
fuse_request_free(fc->destroy_req);
+ if (fc->dax_dev)
+ fuse_free_dax_mem_ranges(&fc->free_ranges);
put_pid_ns(fc->pid_ns);
put_user_ns(fc->user_ns);
fc->release(fc);
@@ -1154,6 +1229,14 @@ int fuse_fill_super_common(struct super_block *sb,
mount_data->fiq_ops, mount_data->fiq_priv);
fc->release = fuse_free_conn;

+ if (mount_data->dax_dev) {
+ err = fuse_dax_mem_range_init(fc, mount_data->dax_dev);
+ if (err) {
+ pr_debug("fuse_dax_mem_range_init() returned %d\n", err);
+ goto err_free_ranges;
+ }
+ }
+
fud = fuse_dev_alloc_install(fc);
if (!fud)
goto err_put_conn;
@@ -1214,6 +1297,9 @@ int fuse_fill_super_common(struct super_block *sb,
dput(root_dentry);
err_dev_free:
fuse_dev_free(fud);
+ err_free_ranges:
+ if (mount_data->dax_dev)
+ fuse_free_dax_mem_ranges(&fc->free_ranges);
err_put_conn:
fuse_conn_put(fc);
sb->s_fs_info = NULL;
diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index 2b790865dc21..76c46edcc8ac 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -453,6 +453,8 @@ static long virtio_fs_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
phys_addr_t offset = PFN_PHYS(pgoff);
size_t max_nr_pages = fs->window_len/PAGE_SIZE - pgoff;

+ pr_debug("virtio_fs_direct_access(): called. nr_pages=%ld max_nr_pages=%zu\n", nr_pages, max_nr_pages);
+
if (kaddr)
*kaddr = fs->window_kaddr + offset;
if (pfn)
--
2.20.1
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