From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- 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