fuse: support splice() reading from fuse device
Allow userspace filesystem implementation to use splice() to read from
the fuse device.
The userspace filesystem can now transfer data coming from a WRITE
request to an arbitrary file descriptor (regular file, block device or
socket) without having to go through a userspace buffer.
The semantics of using splice() to read messages are:
1) with a single splice() call move the whole message from the fuse
device to a temporary pipe
2) read the header from the pipe and determine the message type
3a) if message is a WRITE then splice data from pipe to destination
3b) else read rest of message to userspace buffer
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
This commit is contained in:
Miklos Szeredi
parent
ce534fb052
commit
c3021629a0
228
fs/fuse/dev.c
228
fs/fuse/dev.c
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@ -515,13 +515,12 @@ struct fuse_copy_state {
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};
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static void fuse_copy_init(struct fuse_copy_state *cs, struct fuse_conn *fc,
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int write, struct fuse_req *req,
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int write,
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const struct iovec *iov, unsigned long nr_segs)
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{
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memset(cs, 0, sizeof(*cs));
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cs->fc = fc;
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cs->write = write;
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cs->req = req;
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cs->iov = iov;
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cs->nr_segs = nr_segs;
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}
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@ -532,8 +531,12 @@ static void fuse_copy_finish(struct fuse_copy_state *cs)
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if (cs->currbuf) {
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struct pipe_buffer *buf = cs->currbuf;
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buf->ops->unmap(cs->pipe, buf, cs->mapaddr);
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if (!cs->write) {
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buf->ops->unmap(cs->pipe, buf, cs->mapaddr);
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} else {
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kunmap_atomic(cs->mapaddr, KM_USER0);
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buf->len = PAGE_SIZE - cs->len;
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}
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cs->currbuf = NULL;
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cs->mapaddr = NULL;
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} else if (cs->mapaddr) {
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@ -561,17 +564,39 @@ static int fuse_copy_fill(struct fuse_copy_state *cs)
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if (cs->pipebufs) {
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struct pipe_buffer *buf = cs->pipebufs;
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err = buf->ops->confirm(cs->pipe, buf);
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if (err)
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return err;
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if (!cs->write) {
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err = buf->ops->confirm(cs->pipe, buf);
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if (err)
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return err;
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BUG_ON(!cs->nr_segs);
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cs->currbuf = buf;
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cs->mapaddr = buf->ops->map(cs->pipe, buf, 1);
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cs->len = buf->len;
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cs->buf = cs->mapaddr + buf->offset;
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cs->pipebufs++;
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cs->nr_segs--;
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BUG_ON(!cs->nr_segs);
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cs->currbuf = buf;
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cs->mapaddr = buf->ops->map(cs->pipe, buf, 1);
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cs->len = buf->len;
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cs->buf = cs->mapaddr + buf->offset;
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cs->pipebufs++;
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cs->nr_segs--;
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} else {
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struct page *page;
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if (cs->nr_segs == cs->pipe->buffers)
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return -EIO;
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page = alloc_page(GFP_HIGHUSER);
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if (!page)
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return -ENOMEM;
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buf->page = page;
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buf->offset = 0;
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buf->len = 0;
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cs->currbuf = buf;
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cs->mapaddr = kmap_atomic(page, KM_USER0);
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cs->buf = cs->mapaddr;
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cs->len = PAGE_SIZE;
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cs->pipebufs++;
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cs->nr_segs++;
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}
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} else {
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if (!cs->seglen) {
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BUG_ON(!cs->nr_segs);
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@ -731,6 +756,30 @@ static int fuse_try_move_page(struct fuse_copy_state *cs, struct page **pagep)
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return 1;
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}
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static int fuse_ref_page(struct fuse_copy_state *cs, struct page *page,
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unsigned offset, unsigned count)
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{
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struct pipe_buffer *buf;
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if (cs->nr_segs == cs->pipe->buffers)
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return -EIO;
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unlock_request(cs->fc, cs->req);
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fuse_copy_finish(cs);
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buf = cs->pipebufs;
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page_cache_get(page);
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buf->page = page;
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buf->offset = offset;
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buf->len = count;
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cs->pipebufs++;
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cs->nr_segs++;
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cs->len = 0;
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return 0;
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}
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/*
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* Copy a page in the request to/from the userspace buffer. Must be
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* done atomically
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@ -747,7 +796,9 @@ static int fuse_copy_page(struct fuse_copy_state *cs, struct page **pagep,
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kunmap_atomic(mapaddr, KM_USER1);
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}
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while (count) {
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if (!cs->len) {
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if (cs->write && cs->pipebufs && page) {
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return fuse_ref_page(cs, page, offset, count);
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} else if (!cs->len) {
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if (cs->move_pages && page &&
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offset == 0 && count == PAGE_SIZE) {
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err = fuse_try_move_page(cs, pagep);
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@ -862,11 +913,10 @@ __acquires(&fc->lock)
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*
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* Called with fc->lock held, releases it
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*/
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static int fuse_read_interrupt(struct fuse_conn *fc, struct fuse_req *req,
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const struct iovec *iov, unsigned long nr_segs)
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static int fuse_read_interrupt(struct fuse_conn *fc, struct fuse_copy_state *cs,
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size_t nbytes, struct fuse_req *req)
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__releases(&fc->lock)
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{
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struct fuse_copy_state cs;
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struct fuse_in_header ih;
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struct fuse_interrupt_in arg;
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unsigned reqsize = sizeof(ih) + sizeof(arg);
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@ -882,14 +932,13 @@ __releases(&fc->lock)
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arg.unique = req->in.h.unique;
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spin_unlock(&fc->lock);
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if (iov_length(iov, nr_segs) < reqsize)
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if (nbytes < reqsize)
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return -EINVAL;
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fuse_copy_init(&cs, fc, 1, NULL, iov, nr_segs);
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err = fuse_copy_one(&cs, &ih, sizeof(ih));
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err = fuse_copy_one(cs, &ih, sizeof(ih));
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if (!err)
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err = fuse_copy_one(&cs, &arg, sizeof(arg));
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fuse_copy_finish(&cs);
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err = fuse_copy_one(cs, &arg, sizeof(arg));
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fuse_copy_finish(cs);
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return err ? err : reqsize;
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}
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@ -903,18 +952,13 @@ __releases(&fc->lock)
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* request_end(). Otherwise add it to the processing list, and set
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* the 'sent' flag.
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*/
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static ssize_t fuse_dev_read(struct kiocb *iocb, const struct iovec *iov,
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unsigned long nr_segs, loff_t pos)
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static ssize_t fuse_dev_do_read(struct fuse_conn *fc, struct file *file,
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struct fuse_copy_state *cs, size_t nbytes)
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{
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int err;
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struct fuse_req *req;
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struct fuse_in *in;
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struct fuse_copy_state cs;
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unsigned reqsize;
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struct file *file = iocb->ki_filp;
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struct fuse_conn *fc = fuse_get_conn(file);
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if (!fc)
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return -EPERM;
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restart:
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spin_lock(&fc->lock);
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@ -934,7 +978,7 @@ static ssize_t fuse_dev_read(struct kiocb *iocb, const struct iovec *iov,
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if (!list_empty(&fc->interrupts)) {
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req = list_entry(fc->interrupts.next, struct fuse_req,
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intr_entry);
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return fuse_read_interrupt(fc, req, iov, nr_segs);
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return fuse_read_interrupt(fc, cs, nbytes, req);
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}
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req = list_entry(fc->pending.next, struct fuse_req, list);
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@ -944,7 +988,7 @@ static ssize_t fuse_dev_read(struct kiocb *iocb, const struct iovec *iov,
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in = &req->in;
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reqsize = in->h.len;
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/* If request is too large, reply with an error and restart the read */
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if (iov_length(iov, nr_segs) < reqsize) {
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if (nbytes < reqsize) {
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req->out.h.error = -EIO;
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/* SETXATTR is special, since it may contain too large data */
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if (in->h.opcode == FUSE_SETXATTR)
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@ -953,12 +997,12 @@ static ssize_t fuse_dev_read(struct kiocb *iocb, const struct iovec *iov,
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goto restart;
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}
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spin_unlock(&fc->lock);
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fuse_copy_init(&cs, fc, 1, req, iov, nr_segs);
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err = fuse_copy_one(&cs, &in->h, sizeof(in->h));
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cs->req = req;
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err = fuse_copy_one(cs, &in->h, sizeof(in->h));
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if (!err)
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err = fuse_copy_args(&cs, in->numargs, in->argpages,
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err = fuse_copy_args(cs, in->numargs, in->argpages,
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(struct fuse_arg *) in->args, 0);
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fuse_copy_finish(&cs);
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fuse_copy_finish(cs);
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spin_lock(&fc->lock);
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req->locked = 0;
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if (req->aborted) {
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@ -986,6 +1030,110 @@ static ssize_t fuse_dev_read(struct kiocb *iocb, const struct iovec *iov,
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return err;
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}
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static ssize_t fuse_dev_read(struct kiocb *iocb, const struct iovec *iov,
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unsigned long nr_segs, loff_t pos)
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{
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struct fuse_copy_state cs;
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struct file *file = iocb->ki_filp;
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struct fuse_conn *fc = fuse_get_conn(file);
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if (!fc)
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return -EPERM;
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fuse_copy_init(&cs, fc, 1, iov, nr_segs);
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return fuse_dev_do_read(fc, file, &cs, iov_length(iov, nr_segs));
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}
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static int fuse_dev_pipe_buf_steal(struct pipe_inode_info *pipe,
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struct pipe_buffer *buf)
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{
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return 1;
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}
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static const struct pipe_buf_operations fuse_dev_pipe_buf_ops = {
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.can_merge = 0,
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.map = generic_pipe_buf_map,
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.unmap = generic_pipe_buf_unmap,
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.confirm = generic_pipe_buf_confirm,
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.release = generic_pipe_buf_release,
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.steal = fuse_dev_pipe_buf_steal,
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.get = generic_pipe_buf_get,
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};
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static ssize_t fuse_dev_splice_read(struct file *in, loff_t *ppos,
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struct pipe_inode_info *pipe,
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size_t len, unsigned int flags)
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{
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int ret;
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int page_nr = 0;
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int do_wakeup = 0;
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struct pipe_buffer *bufs;
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struct fuse_copy_state cs;
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struct fuse_conn *fc = fuse_get_conn(in);
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if (!fc)
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return -EPERM;
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bufs = kmalloc(pipe->buffers * sizeof (struct pipe_buffer), GFP_KERNEL);
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if (!bufs)
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return -ENOMEM;
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fuse_copy_init(&cs, fc, 1, NULL, 0);
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cs.pipebufs = bufs;
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cs.pipe = pipe;
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ret = fuse_dev_do_read(fc, in, &cs, len);
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if (ret < 0)
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goto out;
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ret = 0;
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pipe_lock(pipe);
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if (!pipe->readers) {
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send_sig(SIGPIPE, current, 0);
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if (!ret)
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ret = -EPIPE;
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goto out_unlock;
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}
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if (pipe->nrbufs + cs.nr_segs > pipe->buffers) {
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ret = -EIO;
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goto out_unlock;
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}
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while (page_nr < cs.nr_segs) {
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int newbuf = (pipe->curbuf + pipe->nrbufs) & (pipe->buffers - 1);
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struct pipe_buffer *buf = pipe->bufs + newbuf;
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buf->page = bufs[page_nr].page;
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buf->offset = bufs[page_nr].offset;
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buf->len = bufs[page_nr].len;
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buf->ops = &fuse_dev_pipe_buf_ops;
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pipe->nrbufs++;
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page_nr++;
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ret += buf->len;
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if (pipe->inode)
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do_wakeup = 1;
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}
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out_unlock:
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pipe_unlock(pipe);
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if (do_wakeup) {
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smp_mb();
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if (waitqueue_active(&pipe->wait))
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wake_up_interruptible(&pipe->wait);
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kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
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}
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out:
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for (; page_nr < cs.nr_segs; page_nr++)
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page_cache_release(bufs[page_nr].page);
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kfree(bufs);
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return ret;
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}
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static int fuse_notify_poll(struct fuse_conn *fc, unsigned int size,
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struct fuse_copy_state *cs)
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{
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@ -1246,7 +1394,7 @@ static ssize_t fuse_dev_write(struct kiocb *iocb, const struct iovec *iov,
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if (!fc)
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return -EPERM;
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fuse_copy_init(&cs, fc, 0, NULL, iov, nr_segs);
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fuse_copy_init(&cs, fc, 0, iov, nr_segs);
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return fuse_dev_do_write(fc, &cs, iov_length(iov, nr_segs));
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}
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@ -1311,11 +1459,8 @@ static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe,
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}
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pipe_unlock(pipe);
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memset(&cs, 0, sizeof(struct fuse_copy_state));
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cs.fc = fc;
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cs.write = 0;
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fuse_copy_init(&cs, fc, 0, NULL, nbuf);
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cs.pipebufs = bufs;
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cs.nr_segs = nbuf;
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cs.pipe = pipe;
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if (flags & SPLICE_F_MOVE)
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@ -1473,6 +1618,7 @@ const struct file_operations fuse_dev_operations = {
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.llseek = no_llseek,
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.read = do_sync_read,
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.aio_read = fuse_dev_read,
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.splice_read = fuse_dev_splice_read,
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.write = do_sync_write,
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.aio_write = fuse_dev_write,
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.splice_write = fuse_dev_splice_write,
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