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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>
This commit is contained in:
Anton Ivanov 2015-12-21 18:54:00 +00:00 committed by Richard Weinberger
parent 470a166e8c
commit 8c6157b6b3
3 changed files with 26 additions and 22 deletions
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27
arch/um/drivers/ubd_kern.c
View File

@ -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]);

2
arch/um/include/shared/os.h
View File

@ -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);

19
arch/um/os-Linux/file.c
View File

@ -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;