fuse: move the backing file idr and code into a new source file

iomap support for fuse is also going to want the ability to attach
backing files to a fuse filesystem.  Move the fuse_backing code into a
separate file so that both can use it.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/fs/fuse/Makefile b/fs/fuse/Makefile
index 3f0f312a31c1cc200c0c91a086b30a8318e39d94..8ddd8f0b204ee59802f037e4295825656832a5ec 100644 (file)
--- a/fs/fuse/Makefile
+++ b/fs/fuse/Makefile
@@ -13,7 +13,7 @@ obj-$(CONFIG_VIRTIO_FS) += virtiofs.o
 fuse-y := dev.o dir.o file.o inode.o control.o xattr.o acl.o readdir.o ioctl.o
 fuse-y += iomode.o
 fuse-$(CONFIG_FUSE_DAX) += dax.o
-fuse-$(CONFIG_FUSE_PASSTHROUGH) += passthrough.o
+fuse-$(CONFIG_FUSE_PASSTHROUGH) += passthrough.o backing.o
 fuse-$(CONFIG_SYSCTL) += sysctl.o
 fuse-$(CONFIG_FUSE_IO_URING) += dev_uring.o
 

diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c
new file mode 100644 (file)
index 0000000..4afda41
--- /dev/null
+++ b/fs/fuse/backing.c
@@ -0,0 +1,179 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * FUSE passthrough to backing file.
+ *
+ * Copyright (c) 2023 CTERA Networks.
+ */
+
+#include "fuse_i.h"
+
+#include <linux/file.h>
+
+struct fuse_backing *fuse_backing_get(struct fuse_backing *fb)
+{
+       if (fb && refcount_inc_not_zero(&fb->count))
+               return fb;
+       return NULL;
+}
+
+static void fuse_backing_free(struct fuse_backing *fb)
+{
+       pr_debug("%s: fb=0x%p\n", __func__, fb);
+
+       if (fb->file)
+               fput(fb->file);
+       put_cred(fb->cred);
+       kfree_rcu(fb, rcu);
+}
+
+void fuse_backing_put(struct fuse_backing *fb)
+{
+       if (fb && refcount_dec_and_test(&fb->count))
+               fuse_backing_free(fb);
+}
+
+void fuse_backing_files_init(struct fuse_conn *fc)
+{
+       idr_init(&fc->backing_files_map);
+}
+
+static int fuse_backing_id_alloc(struct fuse_conn *fc, struct fuse_backing *fb)
+{
+       int id;
+
+       idr_preload(GFP_KERNEL);
+       spin_lock(&fc->lock);
+       /* FIXME: xarray might be space inefficient */
+       id = idr_alloc_cyclic(&fc->backing_files_map, fb, 1, 0, GFP_ATOMIC);
+       spin_unlock(&fc->lock);
+       idr_preload_end();
+
+       WARN_ON_ONCE(id == 0);
+       return id;
+}
+
+static struct fuse_backing *fuse_backing_id_remove(struct fuse_conn *fc,
+                                                  int id)
+{
+       struct fuse_backing *fb;
+
+       spin_lock(&fc->lock);
+       fb = idr_remove(&fc->backing_files_map, id);
+       spin_unlock(&fc->lock);
+
+       return fb;
+}
+
+static int fuse_backing_id_free(int id, void *p, void *data)
+{
+       struct fuse_backing *fb = p;
+
+       WARN_ON_ONCE(refcount_read(&fb->count) != 1);
+       fuse_backing_free(fb);
+       return 0;
+}
+
+void fuse_backing_files_free(struct fuse_conn *fc)
+{
+       idr_for_each(&fc->backing_files_map, fuse_backing_id_free, NULL);
+       idr_destroy(&fc->backing_files_map);
+}
+
+int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map)
+{
+       struct file *file;
+       struct super_block *backing_sb;
+       struct fuse_backing *fb = NULL;
+       int res;
+
+       pr_debug("%s: fd=%d flags=0x%x\n", __func__, map->fd, map->flags);
+
+       /* TODO: relax CAP_SYS_ADMIN once backing files are visible to lsof */
+       res = -EPERM;
+       if (!fc->passthrough || !capable(CAP_SYS_ADMIN))
+               goto out;
+
+       res = -EINVAL;
+       if (map->flags || map->padding)
+               goto out;
+
+       file = fget_raw(map->fd);
+       res = -EBADF;
+       if (!file)
+               goto out;
+
+       /* read/write/splice/mmap passthrough only relevant for regular files */
+       res = d_is_dir(file->f_path.dentry) ? -EISDIR : -EINVAL;
+       if (!d_is_reg(file->f_path.dentry))
+               goto out_fput;
+
+       backing_sb = file_inode(file)->i_sb;
+       res = -ELOOP;
+       if (backing_sb->s_stack_depth >= fc->max_stack_depth)
+               goto out_fput;
+
+       fb = kmalloc(sizeof(struct fuse_backing), GFP_KERNEL);
+       res = -ENOMEM;
+       if (!fb)
+               goto out_fput;
+
+       fb->file = file;
+       fb->cred = prepare_creds();
+       refcount_set(&fb->count, 1);
+
+       res = fuse_backing_id_alloc(fc, fb);
+       if (res < 0) {
+               fuse_backing_free(fb);
+               fb = NULL;
+       }
+
+out:
+       pr_debug("%s: fb=0x%p, ret=%i\n", __func__, fb, res);
+
+       return res;
+
+out_fput:
+       fput(file);
+       goto out;
+}
+
+int fuse_backing_close(struct fuse_conn *fc, int backing_id)
+{
+       struct fuse_backing *fb = NULL;
+       int err;
+
+       pr_debug("%s: backing_id=%d\n", __func__, backing_id);
+
+       /* TODO: relax CAP_SYS_ADMIN once backing files are visible to lsof */
+       err = -EPERM;
+       if (!fc->passthrough || !capable(CAP_SYS_ADMIN))
+               goto out;
+
+       err = -EINVAL;
+       if (backing_id <= 0)
+               goto out;
+
+       err = -ENOENT;
+       fb = fuse_backing_id_remove(fc, backing_id);
+       if (!fb)
+               goto out;
+
+       fuse_backing_put(fb);
+       err = 0;
+out:
+       pr_debug("%s: fb=0x%p, err=%i\n", __func__, fb, err);
+
+       return err;
+}
+
+struct fuse_backing *fuse_backing_lookup(struct fuse_conn *fc, int backing_id)
+{
+       struct fuse_backing *fb;
+
+       rcu_read_lock();
+       fb = idr_find(&fc->backing_files_map, backing_id);
+       fb = fuse_backing_get(fb);
+       rcu_read_unlock();
+
+       return fb;
+}

diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 48ec7812a1e91386bb35d0cea0dd9d83ba91b5e6..c2f2a48156d6c52c8db87a5c092f51d1627deae9 100644 (file)
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1529,29 +1529,11 @@ struct fuse_file *fuse_file_open(struct fuse_mount *fm, u64 nodeid,
 void fuse_file_release(struct inode *inode, struct fuse_file *ff,
                       unsigned int open_flags, fl_owner_t id, bool isdir);
 
-/* passthrough.c */
-static inline struct fuse_backing *fuse_inode_backing(struct fuse_inode *fi)
-{
-#ifdef CONFIG_FUSE_PASSTHROUGH
-       return READ_ONCE(fi->fb);
-#else
-       return NULL;
-#endif
-}
-
-static inline struct fuse_backing *fuse_inode_backing_set(struct fuse_inode *fi,
-                                                         struct fuse_backing *fb)
-{
-#ifdef CONFIG_FUSE_PASSTHROUGH
-       return xchg(&fi->fb, fb);
-#else
-       return NULL;
-#endif
-}
-
+/* backing.c */
 #ifdef CONFIG_FUSE_PASSTHROUGH
 struct fuse_backing *fuse_backing_get(struct fuse_backing *fb);
 void fuse_backing_put(struct fuse_backing *fb);
+struct fuse_backing *fuse_backing_lookup(struct fuse_conn *fc, int backing_id);
 #else
 
 static inline struct fuse_backing *fuse_backing_get(struct fuse_backing *fb)
@@ -1562,6 +1544,11 @@ static inline struct fuse_backing *fuse_backing_get(struct fuse_backing *fb)
 static inline void fuse_backing_put(struct fuse_backing *fb)
 {
 }
+static inline struct fuse_backing *fuse_backing_lookup(struct fuse_conn *fc,
+                                                      int backing_id)
+{
+       return NULL;
+}
 #endif
 
 void fuse_backing_files_init(struct fuse_conn *fc);
@@ -1569,6 +1556,26 @@ void fuse_backing_files_free(struct fuse_conn *fc);
 int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map);
 int fuse_backing_close(struct fuse_conn *fc, int backing_id);
 
+/* passthrough.c */
+static inline struct fuse_backing *fuse_inode_backing(struct fuse_inode *fi)
+{
+#ifdef CONFIG_FUSE_PASSTHROUGH
+       return READ_ONCE(fi->fb);
+#else
+       return NULL;
+#endif
+}
+
+static inline struct fuse_backing *fuse_inode_backing_set(struct fuse_inode *fi,
+                                                         struct fuse_backing *fb)
+{
+#ifdef CONFIG_FUSE_PASSTHROUGH
+       return xchg(&fi->fb, fb);
+#else
+       return NULL;
+#endif
+}
+
 struct fuse_backing *fuse_passthrough_open(struct file *file, int backing_id);
 void fuse_passthrough_release(struct fuse_file *ff, struct fuse_backing *fb);
 

diff --git a/fs/fuse/passthrough.c b/fs/fuse/passthrough.c
index 0bb80112741a66405ec48341a8529032f01c9e82..72de97c03d0eeb93bf0943ac6f6fb1ca714dec2c 100644 (file)
--- a/fs/fuse/passthrough.c
+++ b/fs/fuse/passthrough.c
@@ -144,163 +144,6 @@ ssize_t fuse_passthrough_mmap(struct file *file, struct vm_area_struct *vma)
        return backing_file_mmap(backing_file, vma, &ctx);
 }
 
-struct fuse_backing *fuse_backing_get(struct fuse_backing *fb)
-{
-       if (fb && refcount_inc_not_zero(&fb->count))
-               return fb;
-       return NULL;
-}
-
-static void fuse_backing_free(struct fuse_backing *fb)
-{
-       pr_debug("%s: fb=0x%p\n", __func__, fb);
-
-       if (fb->file)
-               fput(fb->file);
-       put_cred(fb->cred);
-       kfree_rcu(fb, rcu);
-}
-
-void fuse_backing_put(struct fuse_backing *fb)
-{
-       if (fb && refcount_dec_and_test(&fb->count))
-               fuse_backing_free(fb);
-}
-
-void fuse_backing_files_init(struct fuse_conn *fc)
-{
-       idr_init(&fc->backing_files_map);
-}
-
-static int fuse_backing_id_alloc(struct fuse_conn *fc, struct fuse_backing *fb)
-{
-       int id;
-
-       idr_preload(GFP_KERNEL);
-       spin_lock(&fc->lock);
-       /* FIXME: xarray might be space inefficient */
-       id = idr_alloc_cyclic(&fc->backing_files_map, fb, 1, 0, GFP_ATOMIC);
-       spin_unlock(&fc->lock);
-       idr_preload_end();
-
-       WARN_ON_ONCE(id == 0);
-       return id;
-}
-
-static struct fuse_backing *fuse_backing_id_remove(struct fuse_conn *fc,
-                                                  int id)
-{
-       struct fuse_backing *fb;
-
-       spin_lock(&fc->lock);
-       fb = idr_remove(&fc->backing_files_map, id);
-       spin_unlock(&fc->lock);
-
-       return fb;
-}
-
-static int fuse_backing_id_free(int id, void *p, void *data)
-{
-       struct fuse_backing *fb = p;
-
-       WARN_ON_ONCE(refcount_read(&fb->count) != 1);
-       fuse_backing_free(fb);
-       return 0;
-}
-
-void fuse_backing_files_free(struct fuse_conn *fc)
-{
-       idr_for_each(&fc->backing_files_map, fuse_backing_id_free, NULL);
-       idr_destroy(&fc->backing_files_map);
-}
-
-int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map)
-{
-       struct file *file;
-       struct super_block *backing_sb;
-       struct fuse_backing *fb = NULL;
-       int res;
-
-       pr_debug("%s: fd=%d flags=0x%x\n", __func__, map->fd, map->flags);
-
-       /* TODO: relax CAP_SYS_ADMIN once backing files are visible to lsof */
-       res = -EPERM;
-       if (!fc->passthrough || !capable(CAP_SYS_ADMIN))
-               goto out;
-
-       res = -EINVAL;
-       if (map->flags || map->padding)
-               goto out;
-
-       file = fget_raw(map->fd);
-       res = -EBADF;
-       if (!file)
-               goto out;
-
-       /* read/write/splice/mmap passthrough only relevant for regular files */
-       res = d_is_dir(file->f_path.dentry) ? -EISDIR : -EINVAL;
-       if (!d_is_reg(file->f_path.dentry))
-               goto out_fput;
-
-       backing_sb = file_inode(file)->i_sb;
-       res = -ELOOP;
-       if (backing_sb->s_stack_depth >= fc->max_stack_depth)
-               goto out_fput;
-
-       fb = kmalloc(sizeof(struct fuse_backing), GFP_KERNEL);
-       res = -ENOMEM;
-       if (!fb)
-               goto out_fput;
-
-       fb->file = file;
-       fb->cred = prepare_creds();
-       refcount_set(&fb->count, 1);
-
-       res = fuse_backing_id_alloc(fc, fb);
-       if (res < 0) {
-               fuse_backing_free(fb);
-               fb = NULL;
-       }
-
-out:
-       pr_debug("%s: fb=0x%p, ret=%i\n", __func__, fb, res);
-
-       return res;
-
-out_fput:
-       fput(file);
-       goto out;
-}
-
-int fuse_backing_close(struct fuse_conn *fc, int backing_id)
-{
-       struct fuse_backing *fb = NULL;
-       int err;
-
-       pr_debug("%s: backing_id=%d\n", __func__, backing_id);
-
-       /* TODO: relax CAP_SYS_ADMIN once backing files are visible to lsof */
-       err = -EPERM;
-       if (!fc->passthrough || !capable(CAP_SYS_ADMIN))
-               goto out;
-
-       err = -EINVAL;
-       if (backing_id <= 0)
-               goto out;
-
-       err = -ENOENT;
-       fb = fuse_backing_id_remove(fc, backing_id);
-       if (!fb)
-               goto out;
-
-       fuse_backing_put(fb);
-       err = 0;
-out:
-       pr_debug("%s: fb=0x%p, err=%i\n", __func__, fb, err);
-
-       return err;
-}
-
 /*
  * Setup passthrough to a backing file.
  *
@@ -318,12 +161,8 @@ struct fuse_backing *fuse_passthrough_open(struct file *file, int backing_id)
        if (backing_id <= 0)
                goto out;
 
-       rcu_read_lock();
-       fb = idr_find(&fc->backing_files_map, backing_id);
-       fb = fuse_backing_get(fb);
-       rcu_read_unlock();
-
        err = -ENOENT;
+       fb = fuse_backing_lookup(fc, backing_id);
        if (!fb)
                goto out;