From 9d3788b1c2fa5cb4f14e292232a05c6a5217802d Mon Sep 17 00:00:00 2001

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

Date: Mon, 27 Jan 2020 19:00:44 +0100

Subject: [PATCH 013/116] virtiofsd: Trim down imported files

MIME-Version: 1.0

Content-Type: text/plain; charset=UTF-8

Content-Transfer-Encoding: 8bit

RH-Author: Dr. David Alan Gilbert <dgilbert@redhat.com>

Message-id: <20200127190227.40942-10-dgilbert@redhat.com>

Patchwork-id: 93463

O-Subject: [RHEL-AV-8.2 qemu-kvm PATCH 009/112] virtiofsd: Trim down imported files

Bugzilla: 1694164

RH-Acked-by: Philippe Mathieu-Daudé <philmd@redhat.com>

RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

RH-Acked-by: Sergio Lopez Pascual <slp@redhat.com>

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

There's a lot of the original fuse code we don't need; trim them down.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

with additional trimming by:

Signed-off-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

Reviewed-by: Xiao Yang <yangx.jy@cn.fujitsu.com>

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

(cherry picked from commit a3e23f325439a290c504d6bbc48c2e742149ecab)

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 tools/virtiofsd/buffer.c              |  71 +---

 tools/virtiofsd/fuse.h                |  46 ---

 tools/virtiofsd/fuse_common.h         |  32 --

 tools/virtiofsd/fuse_i.h              |  41 ---

 tools/virtiofsd/fuse_log.h            |   8 -

 tools/virtiofsd/fuse_lowlevel.c       | 675 +---------------------------------

 tools/virtiofsd/fuse_lowlevel.h       |  28 --

 tools/virtiofsd/fuse_opt.h            |   8 -

 tools/virtiofsd/helper.c              | 143 -------

 tools/virtiofsd/passthrough_helpers.h |  26 --

 tools/virtiofsd/passthrough_ll.c      |   1 -

 11 files changed, 8 insertions(+), 1071 deletions(-)

diff --git a/tools/virtiofsd/buffer.c b/tools/virtiofsd/buffer.c

index 5ab9b87..aefb7db 100644

--- a/tools/virtiofsd/buffer.c

+++ b/tools/virtiofsd/buffer.c

@@ -157,73 +157,6 @@ static ssize_t fuse_buf_fd_to_fd(const struct fuse_buf *dst, size_t dst_off,

 	return copied;

 }

-#ifdef HAVE_SPLICE

-static ssize_t fuse_buf_splice(const struct fuse_buf *dst, size_t dst_off,

-			       const struct fuse_buf *src, size_t src_off,

-			       size_t len, enum fuse_buf_copy_flags flags)

-{

-	int splice_flags = 0;

-	off_t *srcpos = NULL;

-	off_t *dstpos = NULL;

-	off_t srcpos_val;

-	off_t dstpos_val;

-	ssize_t res;

-	size_t copied = 0;

-

-	if (flags & FUSE_BUF_SPLICE_MOVE)

-		splice_flags |= SPLICE_F_MOVE;

-	if (flags & FUSE_BUF_SPLICE_NONBLOCK)

-		splice_flags |= SPLICE_F_NONBLOCK;

-

-	if (src->flags & FUSE_BUF_FD_SEEK) {

-		srcpos_val = src->pos + src_off;

-		srcpos = &srcpos_val;

-	}

-	if (dst->flags & FUSE_BUF_FD_SEEK) {

-		dstpos_val = dst->pos + dst_off;

-		dstpos = &dstpos_val;

-	}

-

-	while (len) {

-		res = splice(src->fd, srcpos, dst->fd, dstpos, len,

-			     splice_flags);

-		if (res == -1) {

-			if (copied)

-				break;

-

-			if (errno != EINVAL || (flags & FUSE_BUF_FORCE_SPLICE))

-				return -errno;

-

-			/* Maybe splice is not supported for this combination */

-			return fuse_buf_fd_to_fd(dst, dst_off, src, src_off,

-						 len);

-		}

-		if (res == 0)

-			break;

-

-		copied += res;

-		if (!(src->flags & FUSE_BUF_FD_RETRY) &&

-		    !(dst->flags & FUSE_BUF_FD_RETRY)) {

-			break;

-		}

-

-		len -= res;

-	}

-

-	return copied;

-}

-#else

-static ssize_t fuse_buf_splice(const struct fuse_buf *dst, size_t dst_off,

-			       const struct fuse_buf *src, size_t src_off,

-			       size_t len, enum fuse_buf_copy_flags flags)

-{

-	(void) flags;

-

-	return fuse_buf_fd_to_fd(dst, dst_off, src, src_off, len);

-}

-#endif

-

-

 static ssize_t fuse_buf_copy_one(const struct fuse_buf *dst, size_t dst_off,

 				 const struct fuse_buf *src, size_t src_off,

 				 size_t len, enum fuse_buf_copy_flags flags)

@@ -247,10 +180,8 @@ static ssize_t fuse_buf_copy_one(const struct fuse_buf *dst, size_t dst_off,

 		return fuse_buf_write(dst, dst_off, src, src_off, len);

 	} else if (!dst_is_fd) {

 		return fuse_buf_read(dst, dst_off, src, src_off, len);

-	} else if (flags & FUSE_BUF_NO_SPLICE) {

-		return fuse_buf_fd_to_fd(dst, dst_off, src, src_off, len);

 	} else {

-		return fuse_buf_splice(dst, dst_off, src, src_off, len, flags);

+		return fuse_buf_fd_to_fd(dst, dst_off, src, src_off, len);

 	}

 }

diff --git a/tools/virtiofsd/fuse.h b/tools/virtiofsd/fuse.h

index 883f6e5..3202fba 100644

--- a/tools/virtiofsd/fuse.h

+++ b/tools/virtiofsd/fuse.h

@@ -25,10 +25,6 @@

 #include <sys/statvfs.h>

 #include <sys/uio.h>

-#ifdef __cplusplus

-extern "C" {

-#endif

-

 /* ----------------------------------------------------------- *

  * Basic FUSE API					       *

  * ----------------------------------------------------------- */

@@ -979,44 +975,6 @@ int fuse_loop(struct fuse *f);

 void fuse_exit(struct fuse *f);

 /**

- * FUSE event loop with multiple threads

- *

- * Requests from the kernel are processed, and the appropriate

- * operations are called.  Request are processed in parallel by

- * distributing them between multiple threads.

- *

- * For a description of the return value and the conditions when the

- * event loop exits, refer to the documentation of

- * fuse_session_loop().

- *

- * Note: using fuse_loop() instead of fuse_loop_mt() means you are running in

- * single-threaded mode, and that you will not have to worry about reentrancy,

- * though you will have to worry about recursive lookups. In single-threaded

- * mode, FUSE will wait for one callback to return before calling another.

- *

- * Enabling multiple threads, by using fuse_loop_mt(), will cause FUSE to make

- * multiple simultaneous calls into the various callback functions given by your

- * fuse_operations record.

- *

- * If you are using multiple threads, you can enjoy all the parallel execution

- * and interactive response benefits of threads, and you get to enjoy all the

- * benefits of race conditions and locking bugs, too. Ensure that any code used

- * in the callback function of fuse_operations is also thread-safe.

- *

- * @param f the FUSE handle

- * @param config loop configuration

- * @return see fuse_session_loop()

- *

- * See also: fuse_loop()

- */

-#if FUSE_USE_VERSION < 32

-int fuse_loop_mt_31(struct fuse *f, int clone_fd);

-#define fuse_loop_mt(f, clone_fd) fuse_loop_mt_31(f, clone_fd)

-#else

-int fuse_loop_mt(struct fuse *f, struct fuse_loop_config *config);

-#endif

-

-/**

  * Get the current context

  *

  * The context is only valid for the duration of a filesystem

@@ -1268,8 +1226,4 @@ struct fuse_session *fuse_get_session(struct fuse *f);

  */

 int fuse_open_channel(const char *mountpoint, const char *options);

-#ifdef __cplusplus

-}

-#endif

-

 #endif /* FUSE_H_ */

diff --git a/tools/virtiofsd/fuse_common.h b/tools/virtiofsd/fuse_common.h

index 2d686b2..bf8f8cc 100644

--- a/tools/virtiofsd/fuse_common.h

+++ b/tools/virtiofsd/fuse_common.h

@@ -28,10 +28,6 @@

 #define FUSE_MAKE_VERSION(maj, min)  ((maj) * 10 + (min))

 #define FUSE_VERSION FUSE_MAKE_VERSION(FUSE_MAJOR_VERSION, FUSE_MINOR_VERSION)

-#ifdef __cplusplus

-extern "C" {

-#endif

-

 /**

  * Information about an open file.

  *

@@ -100,30 +96,6 @@ struct fuse_file_info {

 	uint32_t poll_events;

 };

-/**

- * Configuration parameters passed to fuse_session_loop_mt() and

- * fuse_loop_mt().

- */

-struct fuse_loop_config {

-	/**

-	 * whether to use separate device fds for each thread

-	 * (may increase performance)

-	 */

-	int clone_fd;

-

-	/**

-	 * The maximum number of available worker threads before they

-	 * start to get deleted when they become idle. If not

-	 * specified, the default is 10.

-	 *

-	 * Adjusting this has performance implications; a very small number

-	 * of threads in the pool will cause a lot of thread creation and

-	 * deletion overhead and performance may suffer. When set to 0, a new

-	 * thread will be created to service every operation.

-	 */

-	unsigned int max_idle_threads;

-};

-

 /**************************************************************************

  * Capability bits for 'fuse_conn_info.capable' and 'fuse_conn_info.want' *

  **************************************************************************/

@@ -802,10 +774,6 @@ void fuse_remove_signal_handlers(struct fuse_session *se);

 #  error only API version 30 or greater is supported

 #endif

-#ifdef __cplusplus

-}

-#endif

-

 /*

  * This interface uses 64 bit off_t.

diff --git a/tools/virtiofsd/fuse_i.h b/tools/virtiofsd/fuse_i.h

index d38b630..b39522e 100644

--- a/tools/virtiofsd/fuse_i.h

+++ b/tools/virtiofsd/fuse_i.h

@@ -9,8 +9,6 @@

 #include "fuse.h"

 #include "fuse_lowlevel.h"

-struct mount_opts;

-

 struct fuse_req {

 	struct fuse_session *se;

 	uint64_t unique;

@@ -45,7 +43,6 @@ struct fuse_session {

 	char *mountpoint;

 	volatile int exited;

 	int fd;

-	struct mount_opts *mo;

 	int debug;

 	int deny_others;

 	struct fuse_lowlevel_ops op;

@@ -58,7 +55,6 @@ struct fuse_session {

 	struct fuse_req interrupts;

 	pthread_mutex_t lock;

 	int got_destroy;

-	pthread_key_t pipe_key;

 	int broken_splice_nonblock;

 	uint64_t notify_ctr;

 	struct fuse_notify_req notify_list;

@@ -87,53 +83,16 @@ struct fuse_module {

 	int ctr;

 };

-/* ----------------------------------------------------------- *

- * Channel interface (when using -o clone_fd)		       *

- * ----------------------------------------------------------- */

-

-/**

- * Obtain counted reference to the channel

- *

- * @param ch the channel

- * @return the channel

- */

-struct fuse_chan *fuse_chan_get(struct fuse_chan *ch);

-

-/**

- * Drop counted reference to a channel

- *

- * @param ch the channel

- */

-void fuse_chan_put(struct fuse_chan *ch);

-

-struct mount_opts *parse_mount_opts(struct fuse_args *args);

-void destroy_mount_opts(struct mount_opts *mo);

-void fuse_mount_version(void);

-unsigned get_max_read(struct mount_opts *o);

-void fuse_kern_unmount(const char *mountpoint, int fd);

-int fuse_kern_mount(const char *mountpoint, struct mount_opts *mo);

-

 int fuse_send_reply_iov_nofree(fuse_req_t req, int error, struct iovec *iov,

 			       int count);

 void fuse_free_req(fuse_req_t req);

-void cuse_lowlevel_init(fuse_req_t req, fuse_ino_t nodeide, const void *inarg);

-

-int fuse_start_thread(pthread_t *thread_id, void *(*func)(void *), void *arg);

-

-int fuse_session_receive_buf_int(struct fuse_session *se, struct fuse_buf *buf,

-				 struct fuse_chan *ch);

 void fuse_session_process_buf_int(struct fuse_session *se,

 				  const struct fuse_buf *buf, struct fuse_chan *ch);

-struct fuse *fuse_new_31(struct fuse_args *args, const struct fuse_operations *op,

-		      size_t op_size, void *private_data);

-int fuse_loop_mt_32(struct fuse *f, struct fuse_loop_config *config);

-int fuse_session_loop_mt_32(struct fuse_session *se, struct fuse_loop_config *config);

 #define FUSE_MAX_MAX_PAGES 256

 #define FUSE_DEFAULT_MAX_PAGES_PER_REQ 32

 /* room needed in buffer to accommodate header */

 #define FUSE_BUFFER_HEADER_SIZE 0x1000

-

diff --git a/tools/virtiofsd/fuse_log.h b/tools/virtiofsd/fuse_log.h

index 5e112e0..0af700d 100644

--- a/tools/virtiofsd/fuse_log.h

+++ b/tools/virtiofsd/fuse_log.h

@@ -16,10 +16,6 @@

 #include <stdarg.h>

-#ifdef __cplusplus

-extern "C" {

-#endif

-

 /**

  * Log severity level

  *

@@ -75,8 +71,4 @@ void fuse_set_log_func(fuse_log_func_t func);

  */

 void fuse_log(enum fuse_log_level level, const char *fmt, ...);

-#ifdef __cplusplus

-}

-#endif

-

 #endif /* FUSE_LOG_H_ */

diff --git a/tools/virtiofsd/fuse_lowlevel.c b/tools/virtiofsd/fuse_lowlevel.c

index f2d7038..e6fa247 100644

--- a/tools/virtiofsd/fuse_lowlevel.c

+++ b/tools/virtiofsd/fuse_lowlevel.c

@@ -16,7 +16,6 @@

 #include "fuse_kernel.h"

 #include "fuse_opt.h"

 #include "fuse_misc.h"

-#include "mount_util.h"

 #include <stdio.h>

 #include <stdlib.h>

@@ -28,12 +27,6 @@

 #include <assert.h>

 #include <sys/file.h>

-#ifndef F_LINUX_SPECIFIC_BASE

-#define F_LINUX_SPECIFIC_BASE       1024

-#endif

-#ifndef F_SETPIPE_SZ

-#define F_SETPIPE_SZ	(F_LINUX_SPECIFIC_BASE + 7)

-#endif

 #define PARAM(inarg) (((char *)(inarg)) + sizeof(*(inarg)))

@@ -137,7 +130,6 @@ void fuse_free_req(fuse_req_t req)

 	req->u.ni.data = NULL;

 	list_del_req(req);

 	ctr = --req->ctr;

-	fuse_chan_put(req->ch);

 	req->ch = NULL;

 	pthread_mutex_unlock(&se->lock);

 	if (!ctr)

@@ -184,19 +176,7 @@ static int fuse_send_msg(struct fuse_session *se, struct fuse_chan *ch,

 		}

 	}

-	ssize_t res = writev(ch ? ch->fd : se->fd,

-			     iov, count);

-	int err = errno;

-

-	if (res == -1) {

-		assert(se != NULL);

-

-		/* ENOENT means the operation was interrupted */

-		if (!fuse_session_exited(se) && err != ENOENT)

-			perror("fuse: writing device");

-		return -err;

-	}

-

+	abort(); /* virtio should have taken it before here */

 	return 0;

 }

@@ -480,10 +460,6 @@ static int fuse_send_data_iov_fallback(struct fuse_session *se,

 				       struct fuse_bufvec *buf,

 				       size_t len)

 {

-	struct fuse_bufvec mem_buf = FUSE_BUFVEC_INIT(len);

-	void *mbuf;

-	int res;

-

 	/* Optimize common case */

 	if (buf->count == 1 && buf->idx == 0 && buf->off == 0 &&

 	    !(buf->buf[0].flags & FUSE_BUF_IS_FD)) {

@@ -496,350 +472,10 @@ static int fuse_send_data_iov_fallback(struct fuse_session *se,

 		return fuse_send_msg(se, ch, iov, iov_count);

 	}

-	res = posix_memalign(&mbuf, pagesize, len);

-	if (res != 0)

-		return res;

-

-	mem_buf.buf[0].mem = mbuf;

-	res = fuse_buf_copy(&mem_buf, buf, 0);

-	if (res < 0) {

-		free(mbuf);

-		return -res;

-	}

-	len = res;

-

-	iov[iov_count].iov_base = mbuf;

-	iov[iov_count].iov_len = len;

-	iov_count++;

-	res = fuse_send_msg(se, ch, iov, iov_count);

-	free(mbuf);

-

-	return res;

-}

-

-struct fuse_ll_pipe {

-	size_t size;

-	int can_grow;

-	int pipe[2];

-};

-

-static void fuse_ll_pipe_free(struct fuse_ll_pipe *llp)

-{

-	close(llp->pipe[0]);

-	close(llp->pipe[1]);

-	free(llp);

-}

-

-#ifdef HAVE_SPLICE

-#if !defined(HAVE_PIPE2) || !defined(O_CLOEXEC)

-static int fuse_pipe(int fds[2])

-{

-	int rv = pipe(fds);

-

-	if (rv == -1)

-		return rv;

-

-	if (fcntl(fds[0], F_SETFL, O_NONBLOCK) == -1 ||

-	    fcntl(fds[1], F_SETFL, O_NONBLOCK) == -1 ||

-	    fcntl(fds[0], F_SETFD, FD_CLOEXEC) == -1 ||

-	    fcntl(fds[1], F_SETFD, FD_CLOEXEC) == -1) {

-		close(fds[0]);

-		close(fds[1]);

-		rv = -1;

-	}

-	return rv;

-}

-#else

-static int fuse_pipe(int fds[2])

-{

-	return pipe2(fds, O_CLOEXEC | O_NONBLOCK);

-}

-#endif

-

-static struct fuse_ll_pipe *fuse_ll_get_pipe(struct fuse_session *se)

-{

-	struct fuse_ll_pipe *llp = pthread_getspecific(se->pipe_key);

-	if (llp == NULL) {

-		int res;

-

-		llp = malloc(sizeof(struct fuse_ll_pipe));

-		if (llp == NULL)

-			return NULL;

-

-		res = fuse_pipe(llp->pipe);

-		if (res == -1) {

-			free(llp);

-			return NULL;

-		}

-

-		/*

-		 *the default size is 16 pages on linux

-		 */

-		llp->size = pagesize * 16;

-		llp->can_grow = 1;

-

-		pthread_setspecific(se->pipe_key, llp);

-	}

-

-	return llp;

-}

-#endif

-

-static void fuse_ll_clear_pipe(struct fuse_session *se)

-{

-	struct fuse_ll_pipe *llp = pthread_getspecific(se->pipe_key);

-	if (llp) {

-		pthread_setspecific(se->pipe_key, NULL);

-		fuse_ll_pipe_free(llp);

-	}

-}

-

-#if defined(HAVE_SPLICE) && defined(HAVE_VMSPLICE)

-static int read_back(int fd, char *buf, size_t len)

-{

-	int res;

-

-	res = read(fd, buf, len);

-	if (res == -1) {

-		fuse_log(FUSE_LOG_ERR, "fuse: internal error: failed to read back from pipe: %s\n", strerror(errno));

-		return -EIO;

-	}

-	if (res != len) {

-		fuse_log(FUSE_LOG_ERR, "fuse: internal error: short read back from pipe: %i from %zi\n", res, len);

-		return -EIO;

-	}

+	abort(); /* Will have taken vhost path */

 	return 0;

 }

-static int grow_pipe_to_max(int pipefd)

-{

-	int max;

-	int res;

-	int maxfd;

-	char buf[32];

-

-	maxfd = open("/proc/sys/fs/pipe-max-size", O_RDONLY);

-	if (maxfd < 0)

-		return -errno;

-

-	res = read(maxfd, buf, sizeof(buf) - 1);

-	if (res < 0) {

-		int saved_errno;

-

-		saved_errno = errno;

-		close(maxfd);

-		return -saved_errno;

-	}

-	close(maxfd);

-	buf[res] = '\0';

-

-	max = atoi(buf);

-	res = fcntl(pipefd, F_SETPIPE_SZ, max);

-	if (res < 0)

-		return -errno;

-	return max;

-}

-

-static int fuse_send_data_iov(struct fuse_session *se, struct fuse_chan *ch,

-			       struct iovec *iov, int iov_count,

-			       struct fuse_bufvec *buf, unsigned int flags)

-{

-	int res;

-	size_t len = fuse_buf_size(buf);

-	struct fuse_out_header *out = iov[0].iov_base;

-	struct fuse_ll_pipe *llp;

-	int splice_flags;

-	size_t pipesize;

-	size_t total_fd_size;

-	size_t idx;

-	size_t headerlen;

-	struct fuse_bufvec pipe_buf = FUSE_BUFVEC_INIT(len);

-

-	if (se->broken_splice_nonblock)

-		goto fallback;

-

-	if (flags & FUSE_BUF_NO_SPLICE)

-		goto fallback;

-

-	total_fd_size = 0;

-	for (idx = buf->idx; idx < buf->count; idx++) {

-		if (buf->buf[idx].flags & FUSE_BUF_IS_FD) {

-			total_fd_size = buf->buf[idx].size;

-			if (idx == buf->idx)

-				total_fd_size -= buf->off;

-		}

-	}

-	if (total_fd_size < 2 * pagesize)

-		goto fallback;

-

-	if (se->conn.proto_minor < 14 ||

-	    !(se->conn.want & FUSE_CAP_SPLICE_WRITE))

-		goto fallback;

-

-	llp = fuse_ll_get_pipe(se);

-	if (llp == NULL)

-		goto fallback;

-

-

-	headerlen = iov_length(iov, iov_count);

-

-	out->len = headerlen + len;

-

-	/*

-	 * Heuristic for the required pipe size, does not work if the

-	 * source contains less than page size fragments

-	 */

-	pipesize = pagesize * (iov_count + buf->count + 1) + out->len;

-

-	if (llp->size < pipesize) {

-		if (llp->can_grow) {

-			res = fcntl(llp->pipe[0], F_SETPIPE_SZ, pipesize);

-			if (res == -1) {

-				res = grow_pipe_to_max(llp->pipe[0]);

-				if (res > 0)

-					llp->size = res;

-				llp->can_grow = 0;

-				goto fallback;

-			}

-			llp->size = res;

-		}

-		if (llp->size < pipesize)

-			goto fallback;

-	}

-

-

-	res = vmsplice(llp->pipe[1], iov, iov_count, SPLICE_F_NONBLOCK);

-	if (res == -1)

-		goto fallback;

-

-	if (res != headerlen) {

-		res = -EIO;

-		fuse_log(FUSE_LOG_ERR, "fuse: short vmsplice to pipe: %u/%zu\n", res,

-			headerlen);

-		goto clear_pipe;

-	}

-

-	pipe_buf.buf[0].flags = FUSE_BUF_IS_FD;

-	pipe_buf.buf[0].fd = llp->pipe[1];

-

-	res = fuse_buf_copy(&pipe_buf, buf,

-			    FUSE_BUF_FORCE_SPLICE | FUSE_BUF_SPLICE_NONBLOCK);

-	if (res < 0) {

-		if (res == -EAGAIN || res == -EINVAL) {

-			/*

-			 * Should only get EAGAIN on kernels with

-			 * broken SPLICE_F_NONBLOCK support (<=

-			 * 2.6.35) where this error or a short read is

-			 * returned even if the pipe itself is not

-			 * full

-			 *

-			 * EINVAL might mean that splice can't handle

-			 * this combination of input and output.

-			 */

-			if (res == -EAGAIN)

-				se->broken_splice_nonblock = 1;

-

-			pthread_setspecific(se->pipe_key, NULL);

-			fuse_ll_pipe_free(llp);

-			goto fallback;

-		}

-		res = -res;

-		goto clear_pipe;

-	}

-

-	if (res != 0 && res < len) {

-		struct fuse_bufvec mem_buf = FUSE_BUFVEC_INIT(len);

-		void *mbuf;

-		size_t now_len = res;

-		/*

-		 * For regular files a short count is either

-		 *  1) due to EOF, or

-		 *  2) because of broken SPLICE_F_NONBLOCK (see above)

-		 *

-		 * For other inputs it's possible that we overflowed

-		 * the pipe because of small buffer fragments.

-		 */

-

-		res = posix_memalign(&mbuf, pagesize, len);

-		if (res != 0)

-			goto clear_pipe;

-

-		mem_buf.buf[0].mem = mbuf;

-		mem_buf.off = now_len;

-		res = fuse_buf_copy(&mem_buf, buf, 0);

-		if (res > 0) {

-			char *tmpbuf;

-			size_t extra_len = res;

-			/*

-			 * Trickiest case: got more data.  Need to get

-			 * back the data from the pipe and then fall

-			 * back to regular write.

-			 */

-			tmpbuf = malloc(headerlen);

-			if (tmpbuf == NULL) {

-				free(mbuf);