[RFC PATCH v4 16/36] fuse-bpf: Add Rename support

[Daniel Rosenberg]

This adds backing support for FUSE_RENAME and FUSE_RENAME2

Signed-off-by: Daniel Rosenberg <drosen@xxxxxxxxxx>
Signed-off-by: Paul Lawrence <paullawrence@xxxxxxxxxx>
---
 fs/fuse/backing.c | 250 ++++++++++++++++++++++++++++++++++++++++++++++
 fs/fuse/dir.c     |   7 ++
 fs/fuse/fuse_i.h  |  18 ++++
 3 files changed, 275 insertions(+)

diff --git a/fs/fuse/backing.c b/fs/fuse/backing.c
index c2c5cb3d3d6e..79f14634ae6a 100644
--- a/fs/fuse/backing.c
+++ b/fs/fuse/backing.c
@@ -1735,6 +1735,256 @@ int fuse_bpf_rmdir(int *out, struct inode *dir, struct dentry *entry)
 				dir, entry);
 }
 
+static int fuse_rename_backing_common(struct inode *olddir,
+				      struct dentry *oldent,
+				      struct inode *newdir,
+				      struct dentry *newent, unsigned int flags)
+{
+	int err = 0;
+	struct path old_backing_path;
+	struct path new_backing_path;
+	struct dentry *old_backing_dir_dentry;
+	struct dentry *old_backing_dentry;
+	struct dentry *new_backing_dir_dentry;
+	struct dentry *new_backing_dentry;
+	struct dentry *trap = NULL;
+	struct inode *target_inode;
+	struct renamedata rd;
+
+	//TODO Actually deal with changing anything that isn't a flag
+	get_fuse_backing_path(oldent, &old_backing_path);
+	if (!old_backing_path.dentry)
+		return -EBADF;
+	get_fuse_backing_path(newent, &new_backing_path);
+	if (!new_backing_path.dentry) {
+		/*
+		 * TODO A file being moved from a backing path to another
+		 * backing path which is not yet instrumented with FUSE-BPF.
+		 * This may be slow and should be substituted with something
+		 * more clever.
+		 */
+		err = -EXDEV;
+		goto put_old_path;
+	}
+	if (new_backing_path.mnt != old_backing_path.mnt) {
+		err = -EXDEV;
+		goto put_new_path;
+	}
+	old_backing_dentry = old_backing_path.dentry;
+	new_backing_dentry = new_backing_path.dentry;
+	old_backing_dir_dentry = dget_parent(old_backing_dentry);
+	new_backing_dir_dentry = dget_parent(new_backing_dentry);
+	target_inode = d_inode(newent);
+
+	trap = lock_rename(old_backing_dir_dentry, new_backing_dir_dentry);
+	if (trap == old_backing_dentry) {
+		err = -EINVAL;
+		goto put_parents;
+	}
+	if (trap == new_backing_dentry) {
+		err = -ENOTEMPTY;
+		goto put_parents;
+	}
+
+	rd = (struct renamedata) {
+		.old_mnt_idmap = &nop_mnt_idmap,
+		.old_dir = d_inode(old_backing_dir_dentry),
+		.old_dentry = old_backing_dentry,
+		.new_mnt_idmap = &nop_mnt_idmap,
+		.new_dir = d_inode(new_backing_dir_dentry),
+		.new_dentry = new_backing_dentry,
+		.flags = flags,
+	};
+	err = vfs_rename(&rd);
+	if (err)
+		goto unlock;
+	if (target_inode)
+		fsstack_copy_attr_all(target_inode,
+				get_fuse_inode(target_inode)->backing_inode);
+	fsstack_copy_attr_all(d_inode(oldent), d_inode(old_backing_dentry));
+unlock:
+	unlock_rename(old_backing_dir_dentry, new_backing_dir_dentry);
+put_parents:
+	dput(new_backing_dir_dentry);
+	dput(old_backing_dir_dentry);
+put_new_path:
+	path_put(&new_backing_path);
+put_old_path:
+	path_put(&old_backing_path);
+	return err;
+}
+
+struct fuse_rename2_args {
+	struct fuse_rename2_in in;
+	struct fuse_buffer old_name;
+	struct fuse_buffer new_name;
+};
+
+static int fuse_rename2_initialize_in(struct bpf_fuse_args *fa, struct fuse_rename2_args *args,
+				      struct inode *olddir, struct dentry *oldent,
+				      struct inode *newdir, struct dentry *newent,
+				      unsigned int flags)
+{
+	*args = (struct fuse_rename2_args) {
+		.in = (struct fuse_rename2_in) {
+			.newdir = get_node_id(newdir),
+			.flags = flags,
+		},
+		.old_name = (struct fuse_buffer) {
+			.data = (void *) oldent->d_name.name,
+			.size = oldent->d_name.len + 1,
+			.flags = BPF_FUSE_IMMUTABLE,
+		},
+		.new_name = (struct fuse_buffer) {
+			.data = (void *) newent->d_name.name,
+			.size = newent->d_name.len + 1,
+			.flags = BPF_FUSE_IMMUTABLE,
+		},
+
+	};
+	*fa = (struct bpf_fuse_args) {
+		.info = (struct bpf_fuse_meta_info) {
+			.nodeid = get_node_id(olddir),
+			.opcode = FUSE_RENAME2,
+		},
+		.in_numargs = 3,
+		.in_args[0] = (struct bpf_fuse_arg) {
+			.size = sizeof(args->in),
+			.value = &args->in,
+		},
+		.in_args[1] = (struct bpf_fuse_arg) {
+			.is_buffer = true,
+			.buffer = &args->old_name,
+		},
+		.in_args[2] = (struct bpf_fuse_arg) {
+			.is_buffer = true,
+			.buffer = &args->new_name,
+		},
+	};
+
+	return 0;
+}
+
+static int fuse_rename2_initialize_out(struct bpf_fuse_args *fa, struct fuse_rename2_args *args,
+				       struct inode *olddir, struct dentry *oldent,
+				       struct inode *newdir, struct dentry *newent,
+				       unsigned int flags)
+{
+	return 0;
+}
+
+static int fuse_rename2_backing(struct bpf_fuse_args *fa, int *out,
+				struct inode *olddir, struct dentry *oldent,
+				struct inode *newdir, struct dentry *newent,
+				unsigned int flags)
+{
+	const struct fuse_rename2_args *fri = fa->in_args[0].value;
+
+	/* TODO: deal with changing dirs/ents */
+	*out = fuse_rename_backing_common(olddir, oldent, newdir, newent,
+					  fri->in.flags);
+	return *out;
+}
+
+static int fuse_rename2_finalize(struct bpf_fuse_args *fa, int *out,
+				 struct inode *olddir, struct dentry *oldent,
+				 struct inode *newdir, struct dentry *newent,
+				 unsigned int flags)
+{
+	return 0;
+}
+
+int fuse_bpf_rename2(int *out, struct inode *olddir, struct dentry *oldent,
+		     struct inode *newdir, struct dentry *newent,
+		     unsigned int flags)
+{
+	return bpf_fuse_backing(olddir, struct fuse_rename2_args, out,
+				fuse_rename2_initialize_in, fuse_rename2_initialize_out,
+				fuse_rename2_backing, fuse_rename2_finalize,
+				olddir, oldent, newdir, newent, flags);
+}
+
+struct fuse_rename_args {
+	struct fuse_rename_in in;
+	struct fuse_buffer old_name;
+	struct fuse_buffer new_name;
+};
+
+static int fuse_rename_initialize_in(struct bpf_fuse_args *fa, struct fuse_rename_args *args,
+				      struct inode *olddir, struct dentry *oldent,
+				      struct inode *newdir, struct dentry *newent)
+{
+	*args = (struct fuse_rename_args) {
+		.in = (struct fuse_rename_in) {
+			.newdir = get_node_id(newdir),
+		},
+		.old_name = (struct fuse_buffer) {
+			.data = (void *) oldent->d_name.name,
+			.size = oldent->d_name.len + 1,
+			.flags = BPF_FUSE_IMMUTABLE,
+		},
+		.new_name = (struct fuse_buffer) {
+			.data = (void *) newent->d_name.name,
+			.size = newent->d_name.len + 1,
+			.flags = BPF_FUSE_IMMUTABLE,
+		},
+
+	};
+	*fa = (struct bpf_fuse_args) {
+		.info = (struct bpf_fuse_meta_info) {
+			.nodeid = get_node_id(olddir),
+			.opcode = FUSE_RENAME,
+		},
+		.in_numargs = 3,
+		.in_args[0] = (struct bpf_fuse_arg) {
+			.size = sizeof(args->in),
+			.value = &args->in,
+		},
+		.in_args[1] = (struct bpf_fuse_arg) {
+			.is_buffer = true,
+			.buffer = &args->old_name,
+		},
+		.in_args[2] = (struct bpf_fuse_arg) {
+			.is_buffer = true,
+			.buffer = &args->new_name,
+		},
+	};
+
+	return 0;
+}
+
+static int fuse_rename_initialize_out(struct bpf_fuse_args *fa, struct fuse_rename_args *args,
+				      struct inode *olddir, struct dentry *oldent,
+				      struct inode *newdir, struct dentry *newent)
+{
+	return 0;
+}
+
+static int fuse_rename_backing(struct bpf_fuse_args *fa, int *out,
+			       struct inode *olddir, struct dentry *oldent,
+			       struct inode *newdir, struct dentry *newent)
+{
+	/* TODO: deal with changing dirs/ents */
+	*out = fuse_rename_backing_common(olddir, oldent, newdir, newent, 0);
+	return *out;
+}
+
+static int fuse_rename_finalize(struct bpf_fuse_args *fa, int *out,
+				struct inode *olddir, struct dentry *oldent,
+				struct inode *newdir, struct dentry *newent)
+{
+	return 0;
+}
+
+int fuse_bpf_rename(int *out, struct inode *olddir, struct dentry *oldent,
+		    struct inode *newdir, struct dentry *newent)
+{
+	return bpf_fuse_backing(olddir, struct fuse_rename_args, out,
+				fuse_rename_initialize_in, fuse_rename_initialize_out,
+				fuse_rename_backing, fuse_rename_finalize,
+				olddir, oldent, newdir, newent);
+}
+
 static int fuse_unlink_initialize_in(struct bpf_fuse_args *fa, struct fuse_buffer *name,
 				     struct inode *dir, struct dentry *entry)
 {
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 7b661fcd5470..0426243d9345 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1204,6 +1204,10 @@ static int fuse_rename2(struct mnt_idmap *idmap, struct inode *olddir,
 		return -EINVAL;
 
 	if (flags) {
+		if (fuse_bpf_rename2(&err, olddir, oldent, newdir, newent, flags))
+			return err;
+
+		/* TODO: how should this go with bpfs involved? */
 		if (fc->no_rename2 || fc->minor < 23)
 			return -EINVAL;
 
@@ -1215,6 +1219,9 @@ static int fuse_rename2(struct mnt_idmap *idmap, struct inode *olddir,
 			err = -EINVAL;
 		}
 	} else {
+		if (fuse_bpf_rename(&err, olddir, oldent, newdir, newent))
+			return err;
+
 		err = fuse_rename_common(olddir, oldent, newdir, newent, 0,
 					 FUSE_RENAME,
 					 sizeof(struct fuse_rename_in));
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 256e217880c8..8bd78a52a6b5 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -1444,6 +1444,11 @@ int fuse_bpf_create_open(int *out, struct inode *dir, struct dentry *entry,
 int fuse_bpf_mknod(int *out, struct inode *dir, struct dentry *entry, umode_t mode, dev_t rdev);
 int fuse_bpf_mkdir(int *out, struct inode *dir, struct dentry *entry, umode_t mode);
 int fuse_bpf_rmdir(int *out, struct inode *dir, struct dentry *entry);
+int fuse_bpf_rename2(int *out, struct inode *olddir, struct dentry *oldent,
+		     struct inode *newdir, struct dentry *newent,
+		     unsigned int flags);
+int fuse_bpf_rename(int *out, struct inode *olddir, struct dentry *oldent,
+		    struct inode *newdir, struct dentry *newent);
 int fuse_bpf_unlink(int *out, struct inode *dir, struct dentry *entry);
 int fuse_bpf_release(int *out, struct inode *inode, struct fuse_file *ff);
 int fuse_bpf_releasedir(int *out, struct inode *inode, struct fuse_file *ff);
@@ -1486,6 +1491,19 @@ static inline int fuse_bpf_rmdir(int *out, struct inode *dir, struct dentry *ent
 	return 0;
 }
 
+static inline int fuse_bpf_rename2(int *out, struct inode *olddir, struct dentry *oldent,
+				   struct inode *newdir, struct dentry *newent,
+				   unsigned int flags)
+{
+	return 0;
+}
+
+static inline int fuse_bpf_rename(int *out, struct inode *olddir, struct dentry *oldent,
+				  struct inode *newdir, struct dentry *newent)
+{
+	return 0;
+}
+
 static inline int fuse_bpf_unlink(int *out, struct inode *dir, struct dentry *entry)
 {
 	return 0;
-- 
2.44.0.478.gd926399ef9-goog