diff options
Diffstat (limited to 'fs/splice.c')
-rw-r--r-- | fs/splice.c | 345 |
1 files changed, 229 insertions, 116 deletions
diff --git a/fs/splice.c b/fs/splice.c index 3e06611d19ae..004eb1c4ce31 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -33,6 +33,7 @@ #include <linux/fsnotify.h> #include <linux/security.h> #include <linux/gfp.h> +#include <linux/net.h> #include <linux/socket.h> #include <linux/sched/signal.h> @@ -299,20 +300,36 @@ void splice_shrink_spd(struct splice_pipe_desc *spd) kfree(spd->partial); } -/* - * Splice data from an O_DIRECT file into pages and then add them to the output - * pipe. +/** + * copy_splice_read - Copy data from a file and splice the copy into a pipe + * @in: The file to read from + * @ppos: Pointer to the file position to read from + * @pipe: The pipe to splice into + * @len: The amount to splice + * @flags: The SPLICE_F_* flags + * + * This function allocates a bunch of pages sufficient to hold the requested + * amount of data (but limited by the remaining pipe capacity), passes it to + * the file's ->read_iter() to read into and then splices the used pages into + * the pipe. + * + * Return: On success, the number of bytes read will be returned and *@ppos + * will be updated if appropriate; 0 will be returned if there is no more data + * to be read; -EAGAIN will be returned if the pipe had no space, and some + * other negative error code will be returned on error. A short read may occur + * if the pipe has insufficient space, we reach the end of the data or we hit a + * hole. */ -ssize_t direct_splice_read(struct file *in, loff_t *ppos, - struct pipe_inode_info *pipe, - size_t len, unsigned int flags) +ssize_t copy_splice_read(struct file *in, loff_t *ppos, + struct pipe_inode_info *pipe, + size_t len, unsigned int flags) { struct iov_iter to; struct bio_vec *bv; struct kiocb kiocb; struct page **pages; ssize_t ret; - size_t used, npages, chunk, remain, reclaim; + size_t used, npages, chunk, remain, keep = 0; int i; /* Work out how much data we can actually add into the pipe */ @@ -326,7 +343,7 @@ ssize_t direct_splice_read(struct file *in, loff_t *ppos, if (!bv) return -ENOMEM; - pages = (void *)(bv + npages); + pages = (struct page **)(bv + npages); npages = alloc_pages_bulk_array(GFP_USER, npages, pages); if (!npages) { kfree(bv); @@ -349,31 +366,25 @@ ssize_t direct_splice_read(struct file *in, loff_t *ppos, kiocb.ki_pos = *ppos; ret = call_read_iter(in, &kiocb, &to); - reclaim = npages * PAGE_SIZE; - remain = 0; if (ret > 0) { - reclaim -= ret; - remain = ret; + keep = DIV_ROUND_UP(ret, PAGE_SIZE); *ppos = kiocb.ki_pos; - file_accessed(in); - } else if (ret < 0) { - /* - * callers of ->splice_read() expect -EAGAIN on - * "can't put anything in there", rather than -EFAULT. - */ - if (ret == -EFAULT) - ret = -EAGAIN; } + /* + * Callers of ->splice_read() expect -EAGAIN on "can't put anything in + * there", rather than -EFAULT. + */ + if (ret == -EFAULT) + ret = -EAGAIN; + /* Free any pages that didn't get touched at all. */ - reclaim /= PAGE_SIZE; - if (reclaim) { - npages -= reclaim; - release_pages(pages + npages, reclaim); - } + if (keep < npages) + release_pages(pages + keep, npages - keep); /* Push the remaining pages into the pipe. */ - for (i = 0; i < npages; i++) { + remain = ret; + for (i = 0; i < keep; i++) { struct pipe_buffer *buf = pipe_head_buf(pipe); chunk = min_t(size_t, remain, PAGE_SIZE); @@ -390,50 +401,7 @@ ssize_t direct_splice_read(struct file *in, loff_t *ppos, kfree(bv); return ret; } -EXPORT_SYMBOL(direct_splice_read); - -/** - * generic_file_splice_read - splice data from file to a pipe - * @in: file to splice from - * @ppos: position in @in - * @pipe: pipe to splice to - * @len: number of bytes to splice - * @flags: splice modifier flags - * - * Description: - * Will read pages from given file and fill them into a pipe. Can be - * used as long as it has more or less sane ->read_iter(). - * - */ -ssize_t generic_file_splice_read(struct file *in, loff_t *ppos, - struct pipe_inode_info *pipe, size_t len, - unsigned int flags) -{ - struct iov_iter to; - struct kiocb kiocb; - int ret; - - iov_iter_pipe(&to, ITER_DEST, pipe, len); - init_sync_kiocb(&kiocb, in); - kiocb.ki_pos = *ppos; - ret = call_read_iter(in, &kiocb, &to); - if (ret > 0) { - *ppos = kiocb.ki_pos; - file_accessed(in); - } else if (ret < 0) { - /* free what was emitted */ - pipe_discard_from(pipe, to.start_head); - /* - * callers of ->splice_read() expect -EAGAIN on - * "can't put anything in there", rather than -EFAULT. - */ - if (ret == -EFAULT) - ret = -EAGAIN; - } - - return ret; -} -EXPORT_SYMBOL(generic_file_splice_read); +EXPORT_SYMBOL(copy_splice_read); const struct pipe_buf_operations default_pipe_buf_ops = { .release = generic_pipe_buf_release, @@ -448,30 +416,6 @@ const struct pipe_buf_operations nosteal_pipe_buf_ops = { }; EXPORT_SYMBOL(nosteal_pipe_buf_ops); -/* - * Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos' - * using sendpage(). Return the number of bytes sent. - */ -static int pipe_to_sendpage(struct pipe_inode_info *pipe, - struct pipe_buffer *buf, struct splice_desc *sd) -{ - struct file *file = sd->u.file; - loff_t pos = sd->pos; - int more; - - if (!likely(file->f_op->sendpage)) - return -EINVAL; - - more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0; - - if (sd->len < sd->total_len && - pipe_occupancy(pipe->head, pipe->tail) > 1) - more |= MSG_SENDPAGE_NOTLAST; - - return file->f_op->sendpage(file, buf->page, buf->offset, - sd->len, &pos, more); -} - static void wakeup_pipe_writers(struct pipe_inode_info *pipe) { smp_mb(); @@ -652,7 +596,7 @@ static void splice_from_pipe_end(struct pipe_inode_info *pipe, struct splice_des * Description: * This function does little more than loop over the pipe and call * @actor to do the actual moving of a single struct pipe_buffer to - * the desired destination. See pipe_to_file, pipe_to_sendpage, or + * the desired destination. See pipe_to_file, pipe_to_sendmsg, or * pipe_to_user. * */ @@ -833,8 +777,9 @@ done: EXPORT_SYMBOL(iter_file_splice_write); +#ifdef CONFIG_NET /** - * generic_splice_sendpage - splice data from a pipe to a socket + * splice_to_socket - splice data from a pipe to a socket * @pipe: pipe to splice from * @out: socket to write to * @ppos: position in @out @@ -846,13 +791,129 @@ EXPORT_SYMBOL(iter_file_splice_write); * is involved. * */ -ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out, - loff_t *ppos, size_t len, unsigned int flags) +ssize_t splice_to_socket(struct pipe_inode_info *pipe, struct file *out, + loff_t *ppos, size_t len, unsigned int flags) { - return splice_from_pipe(pipe, out, ppos, len, flags, pipe_to_sendpage); -} + struct socket *sock = sock_from_file(out); + struct bio_vec bvec[16]; + struct msghdr msg = {}; + ssize_t ret = 0; + size_t spliced = 0; + bool need_wakeup = false; + + pipe_lock(pipe); -EXPORT_SYMBOL(generic_splice_sendpage); + while (len > 0) { + unsigned int head, tail, mask, bc = 0; + size_t remain = len; + + /* + * Check for signal early to make process killable when there + * are always buffers available + */ + ret = -ERESTARTSYS; + if (signal_pending(current)) + break; + + while (pipe_empty(pipe->head, pipe->tail)) { + ret = 0; + if (!pipe->writers) + goto out; + + if (spliced) + goto out; + + ret = -EAGAIN; + if (flags & SPLICE_F_NONBLOCK) + goto out; + + ret = -ERESTARTSYS; + if (signal_pending(current)) + goto out; + + if (need_wakeup) { + wakeup_pipe_writers(pipe); + need_wakeup = false; + } + + pipe_wait_readable(pipe); + } + + head = pipe->head; + tail = pipe->tail; + mask = pipe->ring_size - 1; + + while (!pipe_empty(head, tail)) { + struct pipe_buffer *buf = &pipe->bufs[tail & mask]; + size_t seg; + + if (!buf->len) { + tail++; + continue; + } + + seg = min_t(size_t, remain, buf->len); + + ret = pipe_buf_confirm(pipe, buf); + if (unlikely(ret)) { + if (ret == -ENODATA) + ret = 0; + break; + } + + bvec_set_page(&bvec[bc++], buf->page, seg, buf->offset); + remain -= seg; + if (remain == 0 || bc >= ARRAY_SIZE(bvec)) + break; + tail++; + } + + if (!bc) + break; + + msg.msg_flags = MSG_SPLICE_PAGES; + if (flags & SPLICE_F_MORE) + msg.msg_flags |= MSG_MORE; + if (remain && pipe_occupancy(pipe->head, tail) > 0) + msg.msg_flags |= MSG_MORE; + + iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, bvec, bc, + len - remain); + ret = sock_sendmsg(sock, &msg); + if (ret <= 0) + break; + + spliced += ret; + len -= ret; + tail = pipe->tail; + while (ret > 0) { + struct pipe_buffer *buf = &pipe->bufs[tail & mask]; + size_t seg = min_t(size_t, ret, buf->len); + + buf->offset += seg; + buf->len -= seg; + ret -= seg; + + if (!buf->len) { + pipe_buf_release(pipe, buf); + tail++; + } + } + + if (tail != pipe->tail) { + pipe->tail = tail; + if (pipe->files) + need_wakeup = true; + } + } + +out: + pipe_unlock(pipe); + if (need_wakeup) + wakeup_pipe_writers(pipe); + return spliced ?: ret; +} +#endif static int warn_unsupported(struct file *file, const char *op) { @@ -874,17 +935,42 @@ static long do_splice_from(struct pipe_inode_info *pipe, struct file *out, } /* - * Attempt to initiate a splice from a file to a pipe. + * Indicate to the caller that there was a premature EOF when reading from the + * source and the caller didn't indicate they would be sending more data after + * this. */ -static long do_splice_to(struct file *in, loff_t *ppos, - struct pipe_inode_info *pipe, size_t len, - unsigned int flags) +static void do_splice_eof(struct splice_desc *sd) +{ + if (sd->splice_eof) + sd->splice_eof(sd); +} + +/** + * vfs_splice_read - Read data from a file and splice it into a pipe + * @in: File to splice from + * @ppos: Input file offset + * @pipe: Pipe to splice to + * @len: Number of bytes to splice + * @flags: Splice modifier flags (SPLICE_F_*) + * + * Splice the requested amount of data from the input file to the pipe. This + * is synchronous as the caller must hold the pipe lock across the entire + * operation. + * + * If successful, it returns the amount of data spliced, 0 if it hit the EOF or + * a hole and a negative error code otherwise. + */ +long vfs_splice_read(struct file *in, loff_t *ppos, + struct pipe_inode_info *pipe, size_t len, + unsigned int flags) { unsigned int p_space; int ret; if (unlikely(!(in->f_mode & FMODE_READ))) return -EBADF; + if (!len) + return 0; /* Don't try to read more the pipe has space for. */ p_space = pipe->max_usage - pipe_occupancy(pipe->head, pipe->tail); @@ -899,8 +985,15 @@ static long do_splice_to(struct file *in, loff_t *ppos, if (unlikely(!in->f_op->splice_read)) return warn_unsupported(in, "read"); + /* + * O_DIRECT and DAX don't deal with the pagecache, so we allocate a + * buffer, copy into it and splice that into the pipe. + */ + if ((in->f_flags & O_DIRECT) || IS_DAX(in->f_mapping->host)) + return copy_splice_read(in, ppos, pipe, len, flags); return in->f_op->splice_read(in, ppos, pipe, len, flags); } +EXPORT_SYMBOL_GPL(vfs_splice_read); /** * splice_direct_to_actor - splices data directly between two non-pipes @@ -956,13 +1049,17 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, */ bytes = 0; len = sd->total_len; + + /* Don't block on output, we have to drain the direct pipe. */ flags = sd->flags; + sd->flags &= ~SPLICE_F_NONBLOCK; /* - * Don't block on output, we have to drain the direct pipe. + * We signal MORE until we've read sufficient data to fulfill the + * request and we keep signalling it if the caller set it. */ - sd->flags &= ~SPLICE_F_NONBLOCK; more = sd->flags & SPLICE_F_MORE; + sd->flags |= SPLICE_F_MORE; WARN_ON_ONCE(!pipe_empty(pipe->head, pipe->tail)); @@ -970,22 +1067,20 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd, size_t read_len; loff_t pos = sd->pos, prev_pos = pos; - ret = do_splice_to(in, &pos, pipe, len, flags); + ret = vfs_splice_read(in, &pos, pipe, len, flags); if (unlikely(ret <= 0)) - goto out_release; + goto read_failure; read_len = ret; sd->total_len = read_len; /* - * If more data is pending, set SPLICE_F_MORE - * If this is the last data and SPLICE_F_MORE was not set - * initially, clears it. + * If we now have sufficient data to fulfill the request then + * we clear SPLICE_F_MORE if it was not set initially. */ - if (read_len < len) - sd->flags |= SPLICE_F_MORE; - else if (!more) + if (read_len >= len && !more) sd->flags &= ~SPLICE_F_MORE; + /* * NOTE: nonblocking mode only applies to the input. We * must not do the output in nonblocking mode as then we @@ -1012,6 +1107,15 @@ done: file_accessed(in); return bytes; +read_failure: + /* + * If the user did *not* set SPLICE_F_MORE *and* we didn't hit that + * "use all of len" case that cleared SPLICE_F_MORE, *and* we did a + * "->splice_in()" that returned EOF (ie zero) *and* we have sent at + * least 1 byte *then* we will also do the ->splice_eof() call. + */ + if (ret == 0 && !more && len > 0 && bytes) + do_splice_eof(sd); out_release: /* * If we did an incomplete transfer we must release @@ -1040,6 +1144,14 @@ static int direct_splice_actor(struct pipe_inode_info *pipe, sd->flags); } +static void direct_file_splice_eof(struct splice_desc *sd) +{ + struct file *file = sd->u.file; + + if (file->f_op->splice_eof) + file->f_op->splice_eof(file); +} + /** * do_splice_direct - splices data directly between two files * @in: file to splice from @@ -1065,6 +1177,7 @@ long do_splice_direct(struct file *in, loff_t *ppos, struct file *out, .flags = flags, .pos = *ppos, .u.file = out, + .splice_eof = direct_file_splice_eof, .opos = opos, }; long ret; @@ -1118,7 +1231,7 @@ long splice_file_to_pipe(struct file *in, pipe_lock(opipe); ret = wait_for_space(opipe, flags); if (!ret) - ret = do_splice_to(in, offset, opipe, len, flags); + ret = vfs_splice_read(in, offset, opipe, len, flags); pipe_unlock(opipe); if (ret > 0) wakeup_pipe_readers(opipe); |