Merge branch 'for-linus-4.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml

Pull UML update from Richard Weinberger:
 "A performance enhancement for UML's block driver"

* 'for-linus-4.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml:
  um: UBD Improvements

3 files changed, 167 insertions, 27 deletions

diff --git a/arch/um/drivers/ubd.h b/arch/um/drivers/ubd.h
index 3b48cd2081ee..cc1cc85f5afc 100644
--- a/arch/um/drivers/ubd.h
+++ b/arch/um/drivers/ubd.h
@@ -11,5 +11,10 @@ extern int start_io_thread(unsigned long sp, int *fds_out);
 extern int io_thread(void *arg);
 extern int kernel_fd;
 
+extern int ubd_read_poll(int timeout);
+extern int ubd_write_poll(int timeout);
+
+#define UBD_REQ_BUFFER_SIZE 64
+
 #endif
 
diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index f3540270d096..85410279beab 100644
--- a/arch/um/drivers/ubd_kern.c
+++ b/arch/um/drivers/ubd_kern.c
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2015-2016 Anton Ivanov (aivanov@brocade.com)
  * Copyright (C) 2000 Jeff Dike (jdike@karaya.com)
  * Licensed under the GPL
  */
@@ -58,6 +59,17 @@ struct io_thread_req {
         int error;
 };
 
+
+static struct io_thread_req * (*irq_req_buffer)[];
+static struct io_thread_req *irq_remainder;
+static int irq_remainder_size;
+
+static struct io_thread_req * (*io_req_buffer)[];
+static struct io_thread_req *io_remainder;
+static int io_remainder_size;
+
+
+
 static inline int ubd_test_bit(__u64 bit, unsigned char *data)
 {
         __u64 n;
@@ -442,29 +454,91 @@ static void do_ubd_request(struct request_queue * q);
 static int thread_fd = -1;
 static LIST_HEAD(restart);
 
-/* XXX - move this inside ubd_intr. */
+/* Function to read several request pointers at a time
+* handling fractional reads if (and as) needed
+*/
+
+static int bulk_req_safe_read(
+        int fd,
+        struct io_thread_req * (*request_buffer)[],
+        struct io_thread_req **remainder,
+        int *remainder_size,
+        int max_recs
+        )
+{
+        int n = 0;
+        int res = 0;
+
+        if (*remainder_size > 0) {
+                memmove(
+                        (char *) request_buffer,
+                        (char *) remainder, *remainder_size
+                );
+                n = *remainder_size;
+        }
+
+        res = os_read_file(
+                        fd,
+                        ((char *) request_buffer) + *remainder_size,
+                        sizeof(struct io_thread_req *)*max_recs
+                                - *remainder_size
+                );
+        if (res > 0) {
+                n += res;
+                if ((n % sizeof(struct io_thread_req *)) > 0) {
+                        /*
+                        * Read somehow returned not a multiple of dword
+                        * theoretically possible, but never observed in the
+                        * wild, so read routine must be able to handle it
+                        */
+                        *remainder_size = n % sizeof(struct io_thread_req *);
+                        WARN(*remainder_size > 0, "UBD IPC read returned a partial result");
+                        memmove(
+                                remainder,
+                                ((char *) request_buffer) +
+                                        (n/sizeof(struct io_thread_req *))*sizeof(struct io_thread_req *),
+                                *remainder_size
+                        );
+                        n = n - *remainder_size;
+                }
+        } else {
+                n = res;
+        }
+        return n;
+}
+
 /* Called without dev->lock held, and only in interrupt context. */
 static void ubd_handler(void)
 {
-        struct io_thread_req *req;
         struct ubd *ubd;
         struct list_head *list, *next_ele;
         unsigned long flags;
         int n;
+        int count;
 
         while(1){
-                n = os_read_file(thread_fd, &req,
-                                 sizeof(struct io_thread_req *));
-                if(n != sizeof(req)){
+                n = bulk_req_safe_read(
+                        thread_fd,
+                        irq_req_buffer,
+                        &irq_remainder,
+                        &irq_remainder_size,
+                        UBD_REQ_BUFFER_SIZE
+                );
+                if (n < 0) {
                         if(n == -EAGAIN)
                                 break;
                         printk(KERN_ERR "spurious interrupt in ubd_handler, "
                                "err = %d\n", -n);
                         return;
                 }
-
-                blk_end_request(req->req, 0, req->length);
-                kfree(req);
+                for (count = 0; count < n/sizeof(struct io_thread_req *); count++) {
+                        blk_end_request(
+                                (*irq_req_buffer)[count]->req,
+                                0,
+                                (*irq_req_buffer)[count]->length
+                        );
+                        kfree((*irq_req_buffer)[count]);
+                }
         }
         reactivate_fd(thread_fd, UBD_IRQ);
 
@@ -1064,6 +1138,28 @@ static int __init ubd_init(void)
                 if (register_blkdev(fake_major, "ubd"))
                         return -1;
         }
+
+        irq_req_buffer = kmalloc(
+                        sizeof(struct io_thread_req *) * UBD_REQ_BUFFER_SIZE,
+                        GFP_KERNEL
+                );
+        irq_remainder = 0;
+
+        if (irq_req_buffer == NULL) {
+                printk(KERN_ERR "Failed to initialize ubd buffering\n");
+                return -1;
+        }
+        io_req_buffer = kmalloc(
+                        sizeof(struct io_thread_req *) * UBD_REQ_BUFFER_SIZE,
+                        GFP_KERNEL
+                );
+
+        io_remainder = 0;
+
+        if (io_req_buffer == NULL) {
+                printk(KERN_ERR "Failed to initialize ubd buffering\n");
+                return -1;
+        }
         platform_driver_register(&ubd_driver);
         mutex_lock(&ubd_lock);
         for (i = 0; i < MAX_DEV; i++){
@@ -1458,31 +1554,51 @@ static int io_count = 0;
 
 int io_thread(void *arg)
 {
-        struct io_thread_req *req;
-        int n;
+        int n, count, written, res;
 
         os_fix_helper_signals();
 
         while(1){
-                n = os_read_file(kernel_fd, &req,
-                                 sizeof(struct io_thread_req *));
-                if(n != sizeof(struct io_thread_req *)){
-                        if(n < 0)
+                n = bulk_req_safe_read(
+                        kernel_fd,
+                        io_req_buffer,
+                        &io_remainder,
+                        &io_remainder_size,
+                        UBD_REQ_BUFFER_SIZE
+                );
+                if (n < 0) {
+                        if (n == -EAGAIN) {
+                                ubd_read_poll(-1);
+                                continue;
+                        } else {
                                 printk("io_thread - read failed, fd = %d, "
-                                       "err = %d\n", kernel_fd, -n);
-                        else {
-                                printk("io_thread - short read, fd = %d, "
-                                       "length = %d\n", kernel_fd, n);
+                                       "err = %d,"
+                                       "reminder = %d\n",
+                                       kernel_fd, -n, io_remainder_size);
                         }
-                        continue;
                 }
-                io_count++;
-                do_io(req);
-                n = os_write_file(kernel_fd, &req,
-                                  sizeof(struct io_thread_req *));
-                if(n != sizeof(struct io_thread_req *))
-                        printk("io_thread - write failed, fd = %d, err = %d\n",
-                               kernel_fd, -n);
+
+                for (count = 0; count < n/sizeof(struct io_thread_req *); count++) {
+                        io_count++;
+                        do_io((*io_req_buffer)[count]);
+                }
+
+                written = 0;
+
+                do {
+                        res = os_write_file(kernel_fd, ((char *) io_req_buffer) + written, n);
+                        if (res > 0) {
+                                written += res;
+                        } else {
+                                if (res != -EAGAIN) {
+                                        printk("io_thread - read failed, fd = %d, "
+                                               "err = %d\n", kernel_fd, -n);
+                                }
+                        }
+                        if (written < n) {
+                                ubd_write_poll(-1);
+                        }
+                } while (written < n);
         }
 
         return 0;
diff --git a/arch/um/drivers/ubd_user.c b/arch/um/drivers/ubd_user.c
index e376f9b9c68d..6f744794d141 100644
--- a/arch/um/drivers/ubd_user.c
+++ b/arch/um/drivers/ubd_user.c
@@ -1,4 +1,5 @@
-/* 
+/*
+ * Copyright (C) 2016 Anton Ivanov (aivanov@brocade.com)
  * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
  * Copyright (C) 2001 Ridgerun,Inc (glonnon@ridgerun.com)
  * Licensed under the GPL
@@ -20,6 +21,9 @@
 
 #include "ubd.h"
 #include <os.h>
+#include <poll.h>
+
+struct pollfd kernel_pollfd;
 
 int start_io_thread(unsigned long sp, int *fd_out)
 {
@@ -32,9 +36,12 @@ int start_io_thread(unsigned long sp, int *fd_out)
         }
 
         kernel_fd = fds[0];
+        kernel_pollfd.fd = kernel_fd;
+        kernel_pollfd.events = POLLIN;
         *fd_out = fds[1];
 
         err = os_set_fd_block(*fd_out, 0);
+        err = os_set_fd_block(kernel_fd, 0);
         if (err) {
                 printk("start_io_thread - failed to set nonblocking I/O.\n");
                 goto out_close;
@@ -57,3 +64,15 @@ int start_io_thread(unsigned long sp, int *fd_out)
  out:
         return err;
 }
+
+int ubd_read_poll(int timeout)
+{
+        kernel_pollfd.events = POLLIN;
+        return poll(&kernel_pollfd, 1, timeout);
+}
+int ubd_write_poll(int timeout)
+{
+        kernel_pollfd.events = POLLOUT;
+        return poll(&kernel_pollfd, 1, timeout);
+}
+