Attachment 232438 Details for Bug 262535 – Patch to add a fallback to Linuxulator sendfile to support any FDs

[patch] Patch to add a fallback to Linuxulator sendfile to support any FDs

linux-sendfile-fallback.patch (text/plain), 5.46 KB, created by James McLaughlin on 2022-03-13 23:17:07 UTC

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Creator: James McLaughlin

Created: 2022-03-13 23:17:07 UTC

Size: 5.46 KB

patch

obsolete

>From 1d5e57c2c942c9541f2da3c0b0cdc0d91ffa2f77 Mon Sep 17 00:00:00 2001
>From: James McLaughlin <james@mclgh.net>
>Date: Sun, 13 Mar 2022 22:31:37 +0000
>Subject: [PATCH] linuxulator: add sendfile fallback for non-socket FDs
>
>---
> sys/compat/linux/linux_socket.c | 166 +++++++++++++++++++++++++++++++-
> 1 file changed, 161 insertions(+), 5 deletions(-)
>
>diff --git a/sys/compat/linux/linux_socket.c b/sys/compat/linux/linux_socket.c
>index d51b9945b43414..1927a235de2287 100644
>--- a/sys/compat/linux/linux_socket.c
>+++ b/sys/compat/linux/linux_socket.c
>@@ -54,6 +54,8 @@ __FBSDID("$FreeBSD$");
> #include <sys/syslog.h>
> #include <sys/un.h>
> #include <sys/unistd.h>
>+#include <sys/protosw.h>
>+#include <sys/vnode.h>
> 
> #include <security/audit/audit.h>
> 
>@@ -2058,6 +2060,143 @@ linux_getsockopt(struct thread *td, struct linux_getsockopt_args *args)
> 	return (error);
> }
> 
>+
>+/*
>+ * Based on sendfile_getsock from kern_sendfile.c
>+ * Determines whether an fd is a stream socket that can be used
>+ * with FreeBSD sendfile.
>+ */
>+static bool
>+_is_stream_socket(struct thread *td, l_int fd)
>+{
>+	int error;
>+	struct file *sock_fp = NULL;
>+	struct socket *so = NULL;
>+
>+	/*
>+	 * The socket must be a stream socket and connected.
>+	 */
>+	error = getsock_cap(td, fd, &cap_send_rights,
>+	    &sock_fp, NULL, NULL);
>+	if (error != 0)
>+		return false;
>+	so = sock_fp->f_data;
>+	if (so->so_type != SOCK_STREAM)
>+		return false;
>+	/*
>+	 * SCTP one-to-one style sockets currently don't work with
>+	 * sendfile().
>+	 */
>+	if (so->so_proto->pr_protocol == IPPROTO_SCTP)
>+		return false;
>+	if (SOLISTENING(so))
>+		return false;
>+
>+	return true;
>+}
>+
>+#define TMPBUF_SIZE 8192
>+
>+static int
>+_sendfile_fallback(struct thread *td, struct file *fp,
>+	struct file *outfp, l_loff_t current_offset,
>+	l_size_t count, off_t *bytes_read)
>+{
>+	int error;
>+	struct uio auio;
>+	struct iovec aiov;
>+	void *tmpbuf;
>+	off_t out_offset;
>+	l_size_t bytes_sent;
>+	l_size_t n_read;
>+
>+	error = (outfp->f_ops->fo_flags & DFLAG_SEEKABLE) != 0 ?
>+		fo_seek(outfp, 0, SEEK_CUR, td) : 0;
>+
>+	if (error != 0)
>+		return (error);
>+
>+	out_offset = td->td_uretoff.tdu_off;
>+
>+	bytes_sent = 0;
>+	tmpbuf = malloc(TMPBUF_SIZE, M_TEMP, M_WAITOK);
>+
>+	if(!tmpbuf) {
>+		error = ENOMEM;
>+		return (error);
>+	}
>+
>+	while(bytes_sent < count) {
>+
>+		off_t to_send = MIN(count - bytes_sent, TMPBUF_SIZE);
>+
>+		/*
>+		 * Read
>+		 */
>+
>+		aiov.iov_base = tmpbuf;
>+		aiov.iov_len = TMPBUF_SIZE;
>+
>+		auio.uio_iov = &aiov;
>+		auio.uio_iovcnt = 1;
>+		auio.uio_segflg = UIO_SYSSPACE;
>+		auio.uio_td = td;
>+
>+		auio.uio_rw = UIO_READ;
>+		auio.uio_offset = current_offset + bytes_sent;
>+		auio.uio_resid = to_send;
>+
>+		error = fo_read(fp, &auio, fp->f_cred, FOF_OFFSET, td);
>+		if (error != 0) {
>+			goto cleanup;
>+		}
>+
>+		n_read = to_send - auio.uio_resid;
>+
>+		if(n_read == 0)
>+			break; /* eof */
>+
>+		/*
>+		 * Write
>+		 */
>+
>+		aiov.iov_base = tmpbuf;
>+		aiov.iov_len = TMPBUF_SIZE;
>+
>+		auio.uio_iov = &aiov;
>+		auio.uio_iovcnt = 1;
>+		auio.uio_segflg = UIO_SYSSPACE;
>+		auio.uio_td = td;
>+
>+		auio.uio_rw = UIO_WRITE;
>+
>+		auio.uio_offset = ((outfp->f_ops->fo_flags & DFLAG_SEEKABLE) != 0) ?
>+			out_offset + bytes_sent :
>+			0;
>+
>+		auio.uio_resid = n_read;
>+
>+		error = fo_write(outfp, &auio, outfp->f_cred, FOF_OFFSET, td);
>+		if (error != 0) {
>+			goto cleanup;
>+		}
>+
>+		bytes_sent += n_read;
>+	}
>+
>+	if((outfp->f_ops->fo_flags & DFLAG_SEEKABLE) != 0) {
>+		error = fo_seek(outfp, out_offset + bytes_sent, SEEK_SET, td);
>+		if (error != 0) {
>+			goto cleanup;
>+		}
>+	}
>+
>+cleanup:
>+	*bytes_read = bytes_sent;
>+	free(tmpbuf, M_TEMP);
>+	return (error);
>+}
>+
> static int
> linux_sendfile_common(struct thread *td, l_int out, l_int in,
>     l_loff_t *offset, l_size_t count)
>@@ -2065,13 +2204,18 @@ linux_sendfile_common(struct thread *td, l_int out, l_int in,
> 	off_t bytes_read;
> 	int error;
> 	l_loff_t current_offset;
>-	struct file *fp;
>+	struct file *fp, *outfp;
>+	bool use_sendfile;
> 
> 	AUDIT_ARG_FD(in);
> 	error = fget_read(td, in, &cap_pread_rights, &fp);
> 	if (error != 0)
> 		return (error);
> 
>+	use_sendfile = _is_stream_socket(td, out) &&
>+		((fp->f_type == DTYPE_VNODE && fp->f_vnode->v_type == VREG) ||
>+		 fp->f_type == DTYPE_SHM);
>+
> 	if (offset != NULL) {
> 		current_offset = *offset;
> 	} else {
>@@ -2090,10 +2234,21 @@ linux_sendfile_common(struct thread *td, l_int out, l_int in,
> 		goto drop;
> 	}
> 
>-	error = fo_sendfile(fp, out, NULL, NULL, current_offset, count,
>-	    &bytes_read, 0, td);
>-	if (error != 0)
>+	if(use_sendfile) {
>+		error = fo_sendfile(fp, out, NULL, NULL, current_offset, count,
>+				&bytes_read, 0, td);
>+	} else {
>+		error = fget_write(td, out, &cap_pwrite_rights, &outfp);
>+		if (error != 0)
>+			return (error);
>+		error = _sendfile_fallback(td, fp, outfp, current_offset, count, &bytes_read);
>+		fdrop(outfp, td);
>+	}
>+
>+	if (error != 0) {
> 		goto drop;
>+	}
>+
> 	current_offset += bytes_read;
> 
> 	if (offset != NULL) {
>@@ -2121,7 +2276,8 @@ linux_sendfile(struct thread *td, struct linux_sendfile_args *arg)
> 	 *   mean send the whole file.)  In linux_sendfile given fds are still
> 	 *   checked for validity when the count is 0.
> 	 * - Linux can send to any fd whereas FreeBSD only supports sockets.
>-	 *   The same restriction follows for linux_sendfile.
>+	 *   We therefore use FreeBSD sendfile where possible for performance,
>+	 *   but fall back on a manual copy (_sendfile_fallback)
> 	 * - Linux doesn't have an equivalent for FreeBSD's flags and sf_hdtr.
> 	 * - Linux takes an offset pointer and updates it to the read location.
> 	 *   FreeBSD takes in an offset and a 'bytes read' parameter which is

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Attachments on bug 262535: 232438