fuse: split out filesystem part of request sending

Create a new source file: req.c and add the request sending entry
functions:

  __fuse_simple_request()
  fuse_simple_background()
  fuse_simple_notify_reply()

Introduce transport layer sending functions that are called by the
respective fs layer function:

  fuse_chan_send()
  fuse_chan_send_bg()
  fuse_chan_send_notify_reply()

Move calculation of request header fields uid, gid and pid from
fuse_get_req() and fuse_force_creads() to a new helper: fuse_fill_creds().

These fileds are now passed to the transport layer via struct fuse_args.

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

fs/fuse/Makefile

@@ -11,7 +11,7 @@ obj-$(CONFIG_CUSE) += cuse.o
 obj-$(CONFIG_VIRTIO_FS) += virtiofs.o
 
 fuse-y := trace.o	# put trace.o first so we see ftrace errors sooner
-fuse-y += dev.o dir.o file.o inode.o control.o xattr.o acl.o readdir.o ioctl.o req_timeout.o
+fuse-y += dev.o dir.o file.o inode.o control.o xattr.o acl.o readdir.o ioctl.o req_timeout.o req.o
 fuse-y += iomode.o
 fuse-$(CONFIG_FUSE_DAX) += dax.o
 fuse-$(CONFIG_FUSE_PASSTHROUGH) += passthrough.o backing.o

fs/fuse/dev.c

@@ -102,75 +102,44 @@ static void fuse_drop_waiting(struct fuse_chan *fch)
 
 static void fuse_put_request(struct fuse_req *req);
 
-static struct fuse_req *fuse_get_req(struct mnt_idmap *idmap,
-				     struct fuse_mount *fm,
-				     bool for_background)
+static struct fuse_req *fuse_get_req(struct fuse_chan *fch, bool for_background)
 {
-	struct fuse_conn *fc = fm->fc;
 	struct fuse_req *req;
-	bool no_idmap = !fm->sb || (fm->sb->s_iflags & SB_I_NOIDMAP);
-	kuid_t fsuid;
-	kgid_t fsgid;
 	int err;
 
-	atomic_inc(&fc->chan->num_waiting);
+	atomic_inc(&fch->num_waiting);
 
-	if (fuse_block_alloc(fc, for_background)) {
+	if (fuse_block_alloc(fch->conn, for_background)) {
 		err = -EINTR;
-		if (wait_event_state_exclusive(fc->chan->blocked_waitq,
-				!fuse_block_alloc(fc, for_background),
+		if (wait_event_state_exclusive(fch->blocked_waitq,
+				!fuse_block_alloc(fch->conn, for_background),
 				(TASK_KILLABLE | TASK_FREEZABLE)))
 			goto out;
 	}
+
 	/* Matches smp_wmb() in fuse_chan_set_initialized() */
 	smp_rmb();
 
 	err = -ENOTCONN;
-	if (!fc->chan->connected)
+	if (!fch->connected)
 		goto out;
 
-	err = -ECONNREFUSED;
-	if (fc->conn_error)
-		goto out;
-
-	req = fuse_request_alloc(fc->chan, GFP_KERNEL);
+	req = fuse_request_alloc(fch, GFP_KERNEL);
 	err = -ENOMEM;
 	if (!req) {
 		if (for_background)
-			wake_up(&fc->chan->blocked_waitq);
+			wake_up(&fch->blocked_waitq);
 		goto out;
 	}
 
-	req->in.h.pid = pid_nr_ns(task_pid(current), fc->pid_ns);
-
 	__set_bit(FR_WAITING, &req->flags);
 	if (for_background)
 		__set_bit(FR_BACKGROUND, &req->flags);
 
-	/*
-	 * Keep the old behavior when idmappings support was not
-	 * declared by a FUSE server.
-	 *
-	 * For those FUSE servers who support idmapped mounts,
-	 * we send UID/GID only along with "inode creation"
-	 * fuse requests, otherwise idmap == &invalid_mnt_idmap and
-	 * req->in.h.{u,g}id will be equal to FUSE_INVALID_UIDGID.
-	 */
-	fsuid = no_idmap ? current_fsuid() : mapped_fsuid(idmap, fc->user_ns);
-	fsgid = no_idmap ? current_fsgid() : mapped_fsgid(idmap, fc->user_ns);
-	req->in.h.uid = from_kuid(fc->user_ns, fsuid);
-	req->in.h.gid = from_kgid(fc->user_ns, fsgid);
-
-	if (no_idmap && unlikely(req->in.h.uid == ((uid_t)-1) ||
-				 req->in.h.gid == ((gid_t)-1))) {
-		fuse_put_request(req);
-		return ERR_PTR(-EOVERFLOW);
-	}
-
 	return req;
 
  out:
-	fuse_drop_waiting(fc->chan);
+	fuse_drop_waiting(fch);
 	return ERR_PTR(err);
 }
 
@@ -783,25 +752,13 @@ static void fuse_adjust_compat(struct fuse_conn *fc, struct fuse_args *args)
 	}
 }
 
-static void fuse_force_creds(struct fuse_mount *fm, struct fuse_req *req)
-{
-	struct fuse_conn *fc = fm->fc;
-
-	if (!fm->sb || fm->sb->s_iflags & SB_I_NOIDMAP) {
-		req->in.h.uid = from_kuid_munged(fc->user_ns, current_fsuid());
-		req->in.h.gid = from_kgid_munged(fc->user_ns, current_fsgid());
-	} else {
-		req->in.h.uid = FUSE_INVALID_UIDGID;
-		req->in.h.gid = FUSE_INVALID_UIDGID;
-	}
-
-	req->in.h.pid = pid_nr_ns(task_pid(current), fc->pid_ns);
-}
-
 static void fuse_args_to_req(struct fuse_req *req, struct fuse_args *args)
 {
 	req->in.h.opcode = args->opcode;
 	req->in.h.nodeid = args->nodeid;
+	req->in.h.uid = args->uid;
+	req->in.h.gid = args->gid;
+	req->in.h.pid = args->pid;
 	req->args = args;
 	if (args->is_ext)
 		req->in.h.total_extlen = args->in_args[args->ext_idx].size / 8;
@@ -809,33 +766,26 @@ static void fuse_args_to_req(struct fuse_req *req, struct fuse_args *args)
 		__set_bit(FR_ASYNC, &req->flags);
 }
 
-ssize_t __fuse_simple_request(struct mnt_idmap *idmap,
-			      struct fuse_mount *fm,
-			      struct fuse_args *args)
+ssize_t fuse_chan_send(struct fuse_chan *fch, struct fuse_args *args)
 {
-	struct fuse_conn *fc = fm->fc;
 	struct fuse_req *req;
 	ssize_t ret;
 
 	if (args->force) {
-		atomic_inc(&fc->chan->num_waiting);
-		req = fuse_request_alloc(fc->chan, GFP_KERNEL | __GFP_NOFAIL);
-
-		if (!args->nocreds)
-			fuse_force_creds(fm, req);
+		atomic_inc(&fch->num_waiting);
+		req = fuse_request_alloc(fch, GFP_KERNEL | __GFP_NOFAIL);
 
 		__set_bit(FR_WAITING, &req->flags);
 		if (!args->abort_on_kill)
 			__set_bit(FR_FORCE, &req->flags);
 	} else {
-		WARN_ON(args->nocreds);
-		req = fuse_get_req(idmap, fm, false);
+		req = fuse_get_req(fch, false);
 		if (IS_ERR(req))
 			return PTR_ERR(req);
 	}
 
 	/* Needs to be done after fuse_get_req() so that fc->minor is valid */
-	fuse_adjust_compat(fc, args);
+	fuse_adjust_compat(fch->conn, args);
 	fuse_args_to_req(req, args);
 
 	if (!args->noreply)
@@ -899,20 +849,17 @@ static int fuse_request_queue_background(struct fuse_req *req)
 	return queued;
 }
 
-int fuse_simple_background(struct fuse_mount *fm, struct fuse_args *args,
-			    gfp_t gfp_flags)
+int fuse_chan_send_bg(struct fuse_chan *fch, struct fuse_args *args, gfp_t gfp_flags)
 {
 	struct fuse_req *req;
 
 	if (args->force) {
-		WARN_ON(!args->nocreds);
-		req = fuse_request_alloc(fm->fc->chan, gfp_flags);
+		req = fuse_request_alloc(fch, gfp_flags);
 		if (!req)
 			return -ENOMEM;
 		__set_bit(FR_BACKGROUND, &req->flags);
 	} else {
-		WARN_ON(args->nocreds);
-		req = fuse_get_req(&invalid_mnt_idmap, fm, true);
+		req = fuse_get_req(fch, true);
 		if (IS_ERR(req))
 			return PTR_ERR(req);
 	}
@@ -926,15 +873,13 @@ int fuse_simple_background(struct fuse_mount *fm, struct fuse_args *args,
 
 	return 0;
 }
-EXPORT_SYMBOL_GPL(fuse_simple_background);
 
-static int fuse_simple_notify_reply(struct fuse_mount *fm,
-				    struct fuse_args *args, u64 unique)
+int fuse_chan_send_notify_reply(struct fuse_chan *fch, struct fuse_args *args, u64 unique)
 {
 	struct fuse_req *req;
-	struct fuse_iqueue *fiq = &fm->fc->chan->iq;
+	struct fuse_iqueue *fiq = &fch->iq;
 
-	req = fuse_get_req(&invalid_mnt_idmap, fm, false);
+	req = fuse_get_req(fch, false);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 

fs/fuse/dev.h

@@ -11,6 +11,7 @@
 struct fuse_conn;
 struct fuse_chan;
 struct fuse_dev;
+struct fuse_args;
 struct file;
 
 struct fuse_chan *fuse_chan_new(void);
@@ -24,6 +25,9 @@ unsigned int fuse_chan_num_waiting(struct fuse_chan *fch);
 void fuse_chan_set_fc(struct fuse_chan *fch, struct fuse_conn *fc);
 void fuse_chan_set_initialized(struct fuse_chan *fch);
 void fuse_chan_io_uring_enable(struct fuse_chan *fch);
+ssize_t fuse_chan_send(struct fuse_chan *fch, struct fuse_args *args);
+int fuse_chan_send_bg(struct fuse_chan *fch, struct fuse_args *args, gfp_t gfp_flags);
+int fuse_chan_send_notify_reply(struct fuse_chan *fch, struct fuse_args *args, u64 unique);
 
 struct fuse_forget_link *fuse_alloc_forget(void);
 void fuse_chan_queue_forget(struct fuse_chan *fch, struct fuse_forget_link *forget,

fs/fuse/fuse_i.h

@@ -941,6 +941,7 @@ static inline ssize_t fuse_simple_idmap_request(struct mnt_idmap *idmap,
 
 int fuse_simple_background(struct fuse_mount *fm, struct fuse_args *args,
 			   gfp_t gfp_flags);
+int fuse_simple_notify_reply(struct fuse_mount *fm, struct fuse_args *args, u64 unique);
 
 void fuse_dentry_tree_init(void);
 void fuse_dentry_tree_cleanup(void);

fs/fuse/req.c

@@ -0,0 +1,99 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include "dev.h"
+#include "fuse_i.h"
+
+static int fuse_fill_creds(struct fuse_mount *fm, struct fuse_args *args, struct mnt_idmap *idmap)
+{
+	struct fuse_conn *fc = fm->fc;
+	bool no_idmap = !fm->sb || (fm->sb->s_iflags & SB_I_NOIDMAP);
+	kuid_t fsuid = mapped_fsuid(idmap, fc->user_ns);
+	kgid_t fsgid = mapped_fsgid(idmap, fc->user_ns);
+
+	args->pid = pid_nr_ns(task_pid(current), fc->pid_ns);
+
+	if (args->force) {
+		if (args->nocreds)
+			return 0;
+
+		if (no_idmap) {
+			args->uid = from_kuid_munged(fc->user_ns, current_fsuid());
+			args->gid = from_kgid_munged(fc->user_ns, current_fsgid());
+		} else {
+			args->uid = FUSE_INVALID_UIDGID;
+			args->gid = FUSE_INVALID_UIDGID;
+		}
+		return 0;
+	}
+
+	WARN_ON(args->nocreds);
+	/*
+	 * Keep the old behavior when idmappings support was not
+	 * declared by a FUSE server.
+	 *
+	 * For those FUSE servers who support idmapped mounts, we send UID/GID
+	 * only along with "inode creation" fuse requests, otherwise idmap ==
+	 * &invalid_mnt_idmap and req->in.h.{u,g}id will be equal to
+	 * FUSE_INVALID_UIDGID.
+	 */
+	if (no_idmap) {
+		fsuid = current_fsuid();
+		fsgid = current_fsgid();
+	}
+	args->uid = from_kuid(fc->user_ns, fsuid);
+	args->gid = from_kgid(fc->user_ns, fsgid);
+
+	if (no_idmap && unlikely(args->uid == ((uid_t)-1) || args->gid == ((gid_t)-1)))
+		return -EOVERFLOW;
+
+	return 0;
+}
+
+static int fuse_req_prep(struct fuse_mount *fm, struct fuse_args *args, struct mnt_idmap *idmap)
+{
+	if (!args->force && fm->fc->conn_error)
+		return -ECONNREFUSED;
+
+	return fuse_fill_creds(fm, args, idmap);
+}
+
+ssize_t __fuse_simple_request(struct mnt_idmap *idmap, struct fuse_mount *fm,
+			      struct fuse_args *args)
+{
+	struct fuse_conn *fc = fm->fc;
+	int err = fuse_req_prep(fm, args, idmap);
+
+	if (err)
+		return err;
+
+	return fuse_chan_send(fc->chan, args);
+}
+
+int fuse_simple_background(struct fuse_mount *fm, struct fuse_args *args, gfp_t gfp_flags)
+{
+	struct fuse_conn *fc = fm->fc;
+	int err;
+
+	WARN_ON(args->force && !args->nocreds);
+
+	err = fuse_req_prep(fm, args, &invalid_mnt_idmap);
+	if (err)
+		return err;
+
+	return fuse_chan_send_bg(fc->chan, args, gfp_flags);
+}
+EXPORT_SYMBOL_GPL(fuse_simple_background);
+
+int fuse_simple_notify_reply(struct fuse_mount *fm, struct fuse_args *args, u64 unique)
+{
+	struct fuse_conn *fc = fm->fc;
+	int err;
+
+	WARN_ON(args->force && !args->nocreds);
+
+	err = fuse_req_prep(fm, args, &invalid_mnt_idmap);
+	if (err)
+		return err;
+
+	return fuse_chan_send_notify_reply(fc->chan, args, unique);
+}