diff options
Diffstat (limited to 'fs/fuse/passthrough.c')
| -rw-r--r-- | fs/fuse/passthrough.c | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/fs/fuse/passthrough.c b/fs/fuse/passthrough.c new file mode 100644 index 000000000000..72de97c03d0e --- /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 <linux/file.h> +#include <linux/backing-file.h> +#include <linux/splice.h> + +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->f_path, 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; +} |