From 5febf432df1cfa5b25d99b54c32103fafbdd0eb9 Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Sun, 16 Aug 2026 15:32:33 +0200 Subject: kbuild: rust: keep Rust objects out of Clang LTO with inline helpers Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit `objtool` errors such as: vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a: can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd The reason is that in such builds, the Clang invocation that compiles the combined Rust plus helpers bitcode emits LLVM bitcode (again) -- the final code generation happens in the linker's LTO step, which the `-mllvm` trap options passed to Clang do not reach. This, in turn, means that unreachable traps are missing, and the impossible paths do not merely fallthrough to the next symbol, but past the end of their own section, since LTO builds place each function in its own section. Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always emits machine code directly, with the traps in place. Assisted-by: LLM Cc: Gary Guo Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- fs/fuse/passthrough.c | 197 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 197 insertions(+) create mode 100644 fs/fuse/passthrough.c (limited to 'fs/fuse/passthrough.c') diff --git a/fs/fuse/passthrough.c b/fs/fuse/passthrough.c new file mode 100644 index 000000000..f2d08ac24 --- /dev/null +++ b/fs/fuse/passthrough.c @@ -0,0 +1,197 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * FUSE passthrough to backing file. + * + * Copyright (c) 2023 CTERA Networks. + */ + +#include "fuse_i.h" + +#include +#include +#include + +static void fuse_file_accessed(struct file *file) +{ + struct inode *inode = file_inode(file); + + fuse_invalidate_atime(inode); +} + +static void fuse_passthrough_end_write(struct kiocb *iocb, ssize_t ret) +{ + struct inode *inode = file_inode(iocb->ki_filp); + + fuse_write_update_attr(inode, iocb->ki_pos, ret); +} + +ssize_t fuse_passthrough_read_iter(struct kiocb *iocb, struct iov_iter *iter) +{ + struct file *file = iocb->ki_filp; + struct fuse_file *ff = file->private_data; + struct file *backing_file = fuse_file_passthrough(ff); + size_t count = iov_iter_count(iter); + ssize_t ret; + struct backing_file_ctx ctx = { + .cred = ff->cred, + .accessed = fuse_file_accessed, + }; + + + pr_debug("%s: backing_file=0x%p, pos=%lld, len=%zu\n", __func__, + backing_file, iocb->ki_pos, count); + + if (!count) + return 0; + + ret = backing_file_read_iter(backing_file, iter, iocb, iocb->ki_flags, + &ctx); + + return ret; +} + +ssize_t fuse_passthrough_write_iter(struct kiocb *iocb, + struct iov_iter *iter) +{ + struct file *file = iocb->ki_filp; + struct inode *inode = file_inode(file); + struct fuse_file *ff = file->private_data; + struct file *backing_file = fuse_file_passthrough(ff); + size_t count = iov_iter_count(iter); + ssize_t ret; + struct backing_file_ctx ctx = { + .cred = ff->cred, + .end_write = fuse_passthrough_end_write, + }; + + pr_debug("%s: backing_file=0x%p, pos=%lld, len=%zu\n", __func__, + backing_file, iocb->ki_pos, count); + + if (!count) + return 0; + + inode_lock(inode); + ret = backing_file_write_iter(backing_file, iter, iocb, iocb->ki_flags, + &ctx); + inode_unlock(inode); + + return ret; +} + +ssize_t fuse_passthrough_splice_read(struct file *in, loff_t *ppos, + struct pipe_inode_info *pipe, + size_t len, unsigned int flags) +{ + struct fuse_file *ff = in->private_data; + struct file *backing_file = fuse_file_passthrough(ff); + struct backing_file_ctx ctx = { + .cred = ff->cred, + .accessed = fuse_file_accessed, + }; + struct kiocb iocb; + ssize_t ret; + + pr_debug("%s: backing_file=0x%p, pos=%lld, len=%zu, flags=0x%x\n", __func__, + backing_file, *ppos, len, flags); + + init_sync_kiocb(&iocb, in); + iocb.ki_pos = *ppos; + ret = backing_file_splice_read(backing_file, &iocb, pipe, len, flags, &ctx); + *ppos = iocb.ki_pos; + + return ret; +} + +ssize_t fuse_passthrough_splice_write(struct pipe_inode_info *pipe, + struct file *out, loff_t *ppos, + size_t len, unsigned int flags) +{ + struct fuse_file *ff = out->private_data; + struct file *backing_file = fuse_file_passthrough(ff); + struct inode *inode = file_inode(out); + ssize_t ret; + struct backing_file_ctx ctx = { + .cred = ff->cred, + .end_write = fuse_passthrough_end_write, + }; + struct kiocb iocb; + + pr_debug("%s: backing_file=0x%p, pos=%lld, len=%zu, flags=0x%x\n", __func__, + backing_file, *ppos, len, flags); + + inode_lock(inode); + init_sync_kiocb(&iocb, out); + iocb.ki_pos = *ppos; + ret = backing_file_splice_write(pipe, backing_file, &iocb, len, flags, &ctx); + *ppos = iocb.ki_pos; + inode_unlock(inode); + + return ret; +} + +ssize_t fuse_passthrough_mmap(struct file *file, struct vm_area_struct *vma) +{ + struct fuse_file *ff = file->private_data; + struct file *backing_file = fuse_file_passthrough(ff); + struct backing_file_ctx ctx = { + .cred = ff->cred, + .accessed = fuse_file_accessed, + }; + + pr_debug("%s: backing_file=0x%p, start=%lu, end=%lu\n", __func__, + backing_file, vma->vm_start, vma->vm_end); + + return backing_file_mmap(backing_file, vma, &ctx); +} + +/* + * Setup passthrough to a backing file. + * + * Returns an fb object with elevated refcount to be stored in fuse inode. + */ +struct fuse_backing *fuse_passthrough_open(struct file *file, int backing_id) +{ + struct fuse_file *ff = file->private_data; + struct fuse_conn *fc = ff->fm->fc; + struct fuse_backing *fb = NULL; + struct file *backing_file; + int err; + + err = -EINVAL; + if (backing_id <= 0) + goto out; + + err = -ENOENT; + fb = fuse_backing_lookup(fc, backing_id); + if (!fb) + goto out; + + /* Allocate backing file per fuse file to store fuse path */ + backing_file = backing_file_open(file, file->f_flags, + &fb->file->f_path, fb->cred); + err = PTR_ERR(backing_file); + if (IS_ERR(backing_file)) { + fuse_backing_put(fb); + goto out; + } + + err = 0; + ff->passthrough = backing_file; + ff->cred = get_cred(fb->cred); +out: + pr_debug("%s: backing_id=%d, fb=0x%p, backing_file=0x%p, err=%i\n", __func__, + backing_id, fb, ff->passthrough, err); + + return err ? ERR_PTR(err) : fb; +} + +void fuse_passthrough_release(struct fuse_file *ff, struct fuse_backing *fb) +{ + pr_debug("%s: fb=0x%p, backing_file=0x%p\n", __func__, + fb, ff->passthrough); + + fput(ff->passthrough); + ff->passthrough = NULL; + put_cred(ff->cred); + ff->cred = NULL; +} -- cgit v1.3.1