Commit 8c6157b6 authored by Anton Ivanov's avatar Anton Ivanov Committed by Richard Weinberger
Browse files

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



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

Signed-off-by: default avatarAnton Ivanov <aivanov@brocade.com>
Signed-off-by: default avatarRichard Weinberger <richard@nod.at>
parent 470a166e

arch/um/drivers/ubd_kern.c

+5 −22
Original line number Diff line number Diff line
@@ -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]);

arch/um/include/shared/os.h

+2 −0
Original line number Diff line number Diff line
@@ -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);

arch/um/os-Linux/file.c

+19 −0
Original line number Diff line number Diff line
@@ -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;