Upon completion of a LOOKUP, if we're in famfs-mode we do a GET_FMAP to
retrieve and cache up the file-to-dax map in the kernel. If this
succeeds, read/write/mmap are resolved direct-to-dax with no upcalls.
Signed-off-by: John Groves <j...@groves.net>
---
fs/fuse/dir.c | 69 +++++++++++++++++++++++++++++++++++++++
fs/fuse/fuse_i.h | 36 +++++++++++++++++++-
fs/fuse/inode.c | 15 +++++++++
include/uapi/linux/fuse.h | 4 +++
4 files changed, 123 insertions(+), 1 deletion(-)
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index bc29db0117f4..ae135c55b9f6 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -359,6 +359,56 @@ bool fuse_invalid_attr(struct fuse_attr *attr)
return !fuse_valid_type(attr->mode) || !fuse_valid_size(attr->size);
}
+#define FMAP_BUFSIZE 4096
+
+#if IS_ENABLED(CONFIG_FUSE_FAMFS_DAX)
+static void
+fuse_get_fmap_init(
+ struct fuse_conn *fc,
+ struct fuse_args *args,
+ u64 nodeid,
+ void *outbuf,
+ size_t outbuf_size)
+{
+ memset(outbuf, 0, outbuf_size);
+ args->opcode = FUSE_GET_FMAP;
+ args->nodeid = nodeid;
+
+ args->in_numargs = 0;
+
+ args->out_numargs = 1;
+ args->out_args[0].size = FMAP_BUFSIZE;
+ args->out_args[0].value = outbuf;
+}
+
+static int
+fuse_get_fmap(struct fuse_mount *fm, struct inode *inode, u64 nodeid)
+{
+ size_t fmap_size;
+ void *fmap_buf;
+ int err;
+
+ pr_notice("%s: nodeid=%lld, inode=%llx\n", __func__,
+ nodeid, (u64)inode);
+ fmap_buf = kcalloc(1, FMAP_BUFSIZE, GFP_KERNEL);
+ FUSE_ARGS(args);
+ fuse_get_fmap_init(fm->fc, &args, nodeid, fmap_buf, FMAP_BUFSIZE);
+
+ /* Send GET_FMAP command */
+ err = fuse_simple_request(fm, &args);
+ if (err) {
+ pr_err("%s: err=%d from fuse_simple_request()\n",
+ __func__, err);
+ return err;
+ }
+
+ fmap_size = args.out_args[0].size;
+ pr_notice("%s: nodei=%lld fmap_size=%ld\n", __func__, nodeid,
fmap_size);
+
+ return 0;
+}
+#endif
+
int fuse_lookup_name(struct super_block *sb, u64 nodeid, const struct qstr
*name,
struct fuse_entry_out *outarg, struct inode **inode)
{
@@ -404,6 +454,25 @@ int fuse_lookup_name(struct super_block *sb, u64 nodeid,
const struct qstr *name
fuse_queue_forget(fm->fc, forget, outarg->nodeid, 1);
goto out;
}
+
+#if IS_ENABLED(CONFIG_FUSE_FAMFS_DAX)
+ if (fm->fc->famfs_iomap) {
+ if (S_ISREG((*inode)->i_mode)) {
+ /* Note Lookup returns the looked-up inode in the attr
+ * struct, but not in outarg->nodeid !
+ */
+ pr_notice("%s: outarg: size=%d nodeid=%lld
attr.ino=%lld\n",
+ __func__, args.out_args[0].size,
outarg->nodeid,
+ outarg->attr.ino);
+ /* Get the famfs fmap */
+ fuse_get_fmap(fm, *inode, outarg->attr.ino);
+ } else
+ pr_notice("%s: no get_fmap for non-regular file\n",
+ __func__);
+ } else
+ pr_notice("%s: fc->dax_iomap is not set\n", __func__);
+#endif
+
err = 0;
out_put_forget:
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 931613102d32..437177c2f092 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -193,6 +193,10 @@ struct fuse_inode {
/** Reference to backing file in passthrough mode */
struct fuse_backing *fb;
#endif
+
+#if IS_ENABLED(CONFIG_FUSE_FAMFS_DAX)
+ void *famfs_meta;
+#endif
};
/** FUSE inode state bits */
@@ -942,6 +946,8 @@ struct fuse_conn {
#endif
#if IS_ENABLED(CONFIG_FUSE_FAMFS_DAX)
+ struct rw_semaphore famfs_devlist_sem;
+ struct famfs_dax_devlist *dax_devlist;
char *shadow;
#endif
};
@@ -1432,11 +1438,14 @@ void fuse_free_conn(struct fuse_conn *fc);
/* dax.c */
+static inline int fuse_file_famfs(struct fuse_inode *fi); /* forward */
+
/* This macro is used by virtio_fs, but now it also needs to filter for
* "not famfs"
*/
#define FUSE_IS_VIRTIO_DAX(fuse_inode) (IS_ENABLED(CONFIG_FUSE_DAX) \
- && IS_DAX(&fuse_inode->inode))
+ && IS_DAX(&fuse_inode->inode) \
+ && !fuse_file_famfs(fuse_inode))
ssize_t fuse_dax_read_iter(struct kiocb *iocb, struct iov_iter *to);
ssize_t fuse_dax_write_iter(struct kiocb *iocb, struct iov_iter *from);
@@ -1547,4 +1556,29 @@ extern void fuse_sysctl_unregister(void);
#define fuse_sysctl_unregister() do { } while (0)
#endif /* CONFIG_SYSCTL */
+/* famfs.c */
+static inline struct fuse_backing *famfs_meta_set(struct fuse_inode *fi,
+ void *meta)
+{
+#if IS_ENABLED(CONFIG_FUSE_FAMFS_DAX)
+ return xchg(&fi->famfs_meta, meta);
+#else
+ return NULL;
+#endif
+}
+
+static inline void famfs_meta_free(struct fuse_inode *fi)
+{
+ /* Stub wil be connected in a subsequent commit */
+}
+
+static inline int fuse_file_famfs(struct fuse_inode *fi)
+{
+#if IS_ENABLED(CONFIG_FUSE_FAMFS_DAX)
+ return (fi->famfs_meta != NULL);
+#else
+ return 0;
+#endif
+}
+
#endif /* _FS_FUSE_I_H */
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 7f4b73e739cb..848c8818e6f7 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -117,6 +117,9 @@ static struct inode *fuse_alloc_inode(struct super_block
*sb)
if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
fuse_inode_backing_set(fi, NULL);
+ if (IS_ENABLED(CONFIG_FUSE_FAMFS_DAX))
+ famfs_meta_set(fi, NULL);
+
return &fi->inode;
out_free_forget:
@@ -138,6 +141,13 @@ static void fuse_free_inode(struct inode *inode)
if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
fuse_backing_put(fuse_inode_backing(fi));
+#if IS_ENABLED(CONFIG_FUSE_FAMFS_DAX)
+ if (S_ISREG(inode->i_mode) && fi->famfs_meta) {
+ famfs_meta_free(fi);
+ famfs_meta_set(fi, NULL);
+ }
+#endif
+
kmem_cache_free(fuse_inode_cachep, fi);
}
@@ -1002,6 +1012,11 @@ void fuse_conn_init(struct fuse_conn *fc, struct
fuse_mount *fm,
if (IS_ENABLED(CONFIG_FUSE_PASSTHROUGH))
fuse_backing_files_init(fc);
+ if (IS_ENABLED(CONFIG_FUSE_FAMFS_DAX)) {
+ pr_notice("%s: Kernel is FUSE_FAMFS_DAX capable\n", __func__);
+ init_rwsem(&fc->famfs_devlist_sem);
+ }
+
INIT_LIST_HEAD(&fc->mounts);
list_add(&fm->fc_entry, &fc->mounts);
fm->fc = fc;
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index f9e14180367a..d85fb692cf3b 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -652,6 +652,10 @@ enum fuse_opcode {
FUSE_TMPFILE = 51,
FUSE_STATX = 52,
+ /* Famfs / devdax opcodes */
+ FUSE_GET_FMAP = 53,
+ FUSE_GET_DAXDEV = 54,
+
/* CUSE specific operations */
CUSE_INIT = 4096,
--
2.49.0
