um: Update UBD to use pread/pwrite family of functions

This decreases the number of syscalls per read/write by half.

Signed-off-by: Anton Ivanov <aivanov@brocade.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index e8ab93c3e638e160e300f016588184b12cc26bd8..39ba20755e035635a35967561ff49c3fb7a7ac95 100644 (file)
--- a/arch/um/drivers/ubd_kern.c
+++ b/arch/um/drivers/ubd_kern.c
@@ -535,11 +535,7 @@ static int read_cow_bitmap(int fd, void *buf, int offset, int len)
 {
        int err;
 
-       err = os_seek_file(fd, offset);
-       if (err < 0)
-               return err;
-
-       err = os_read_file(fd, buf, len);
+       err = os_pread_file(fd, buf, len, offset);
        if (err < 0)
                return err;
 
@@ -1377,14 +1373,8 @@ static int update_bitmap(struct io_thread_req *req)
        if(req->cow_offset == -1)
                return 0;
 
-       n = os_seek_file(req->fds[1], req->cow_offset);
-       if(n < 0){
-               printk("do_io - bitmap lseek failed : err = %d\n", -n);
-               return 1;
-       }
-
-       n = os_write_file(req->fds[1], &req->bitmap_words,
-                         sizeof(req->bitmap_words));
+       n = os_pwrite_file(req->fds[1], &req->bitmap_words,
+                         sizeof(req->bitmap_words), req->cow_offset);
        if(n != sizeof(req->bitmap_words)){
                printk("do_io - bitmap update failed, err = %d fd = %d\n", -n,
                       req->fds[1]);
@@ -1399,7 +1389,6 @@ static void do_io(struct io_thread_req *req)
        char *buf;
        unsigned long len;
        int n, nsectors, start, end, bit;
-       int err;
        __u64 off;
 
        if (req->op == UBD_FLUSH) {
@@ -1428,18 +1417,12 @@ static void do_io(struct io_thread_req *req)
                len = (end - start) * req->sectorsize;
                buf = &req->buffer[start * req->sectorsize];
 
-               err = os_seek_file(req->fds[bit], off);
-               if(err < 0){
-                       printk("do_io - lseek failed : err = %d\n", -err);
-                       req->error = 1;
-                       return;
-               }
                if(req->op == UBD_READ){
                        n = 0;
                        do {
                                buf = &buf[n];
                                len -= n;
-                               n = os_read_file(req->fds[bit], buf, len);
+                               n = os_pread_file(req->fds[bit], buf, len, off);
                                if (n < 0) {
                                        printk("do_io - read failed, err = %d "
                                               "fd = %d\n", -n, req->fds[bit]);
@@ -1449,7 +1432,7 @@ static void do_io(struct io_thread_req *req)
                        } while((n < len) && (n != 0));
                        if (n < len) memset(&buf[n], 0, len - n);
                } else {
-                       n = os_write_file(req->fds[bit], buf, len);
+                       n = os_pwrite_file(req->fds[bit], buf, len, off);
                        if(n != len){
                                printk("do_io - write failed err = %d "
                                       "fd = %d\n", -n, req->fds[bit]);

diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h
index 868e6c3f83dd2f7f1b50f7c16fe2ec71bfb026f4..7a04ddd85334db17160fcbc2a97bba0396019523 100644 (file)
--- a/arch/um/include/shared/os.h
+++ b/arch/um/include/shared/os.h
@@ -146,6 +146,8 @@ extern int os_read_file(int fd, void *buf, int len);
 extern int os_write_file(int fd, const void *buf, int count);
 extern int os_sync_file(int fd);
 extern int os_file_size(const char *file, unsigned long long *size_out);
+extern int os_pread_file(int fd, void *buf, int len, unsigned long long offset);
+extern int os_pwrite_file(int fd, const void *buf, int count, unsigned long long offset);
 extern int os_file_modtime(const char *file, unsigned long *modtime);
 extern int os_pipe(int *fd, int stream, int close_on_exec);
 extern int os_set_fd_async(int fd);

diff --git a/arch/um/os-Linux/file.c b/arch/um/os-Linux/file.c
index 26e0164895e46aacd28e7f8a749d6ecda213ded0..2db18cbbb0eaba83aba45bd809ba4ed0834e80b1 100644 (file)
--- a/arch/um/os-Linux/file.c
+++ b/arch/um/os-Linux/file.c
@@ -264,6 +264,15 @@ int os_read_file(int fd, void *buf, int len)
        return n;
 }
 
+int os_pread_file(int fd, void *buf, int len, unsigned long long offset)
+{
+       int n = pread(fd, buf, len, offset);
+
+       if (n < 0)
+               return -errno;
+       return n;
+}
+
 int os_write_file(int fd, const void *buf, int len)
 {
        int n = write(fd, (void *) buf, len);
@@ -282,6 +291,16 @@ int os_sync_file(int fd)
        return n;
 }
 
+int os_pwrite_file(int fd, const void *buf, int len, unsigned long long offset)
+{
+       int n = pwrite(fd, (void *) buf, len, offset);
+
+       if (n < 0)
+               return -errno;
+       return n;
+}
+
+
 int os_file_size(const char *file, unsigned long long *size_out)
 {
        struct uml_stat buf;