Avoid using BLKFLSBUF.

Now that we use O_DIRECT for all device IO, BLKFLSBUF is not needed to
ensure we get current data, and it can impose a cost if any flush-out
is needed.  So remove it.

To be safe, add O_DIRECT to one place where it isn't currently used:
when reading a bitmap.

Signed-off-by: NeilBrown <[email protected]>

Author: neilbrown

bitmap.c

@@ -207,7 +207,7 @@ bitmap_info_t *bitmap_file_read(char *filename, int brief, struct supertype **st
 		return NULL;
 	}
 	if ((S_IFMT & stb.st_mode) == S_IFBLK) {
-		fd = open(filename, O_RDONLY);
+		fd = open(filename, O_RDONLY|O_DIRECT);
 		if (fd < 0) {
 			pr_err("failed to open bitmap file %s: %s\n",
 				filename, strerror(errno));
@@ -225,7 +225,6 @@ bitmap_info_t *bitmap_file_read(char *filename, int brief, struct supertype **st
 		} else
 			st->ss->locate_bitmap(st, fd);
 
-		ioctl(fd, BLKFLSBUF, 0); /* make sure we read current data */
 		*stp = st;
 	} else {
 		fd = open(filename, O_RDONLY|O_DIRECT);

super-gpt.c

@@ -82,8 +82,6 @@ static int load_gpt(struct supertype *st, int fd, char *devname)
 		return 1;
 	}
 
-	ioctl(fd, BLKFLSBUF, 0); /* make sure we read current data */
-
 	lseek(fd, 0, 0);
 	if (read(fd, super, sizeof(*super)) != sizeof(*super)) {
 	no_read:

super-mbr.c

@@ -86,8 +86,6 @@ static int load_super_mbr(struct supertype *st, int fd, char *devname)
 		return 1;
 	}
 
-	ioctl(fd, BLKFLSBUF, 0); /* make sure we read current data */
-
 	lseek(fd, 0, 0);
 	if (read(fd, super, sizeof(*super)) != sizeof(*super)) {
 		if (devname)
@@ -126,8 +124,6 @@ static int store_mbr(struct supertype *st, int fd)
 		return 1;
 	}
 
-	ioctl(fd, BLKFLSBUF, 0); /* make sure we read current data */
-
 	lseek(fd, 0, 0);
 	if (read(fd, old, sizeof(*old)) != sizeof(*old)) {
 		free(old);

super0.c

@@ -870,8 +870,6 @@ static int load_super0(struct supertype *st, int fd, char *devname)
 
 	offset *= 512;
 
-	ioctl(fd, BLKFLSBUF, 0); /* make sure we read current data */
-
 	if (lseek64(fd, offset, 0)< 0LL) {
 		if (devname)
 			pr_err("Cannot seek to superblock on %s: %s\n",

super1.c

@@ -1633,9 +1633,6 @@ static int load_super1(struct supertype *st, int fd, char *devname)
 		return -EINVAL;
 	}
 
-	ioctl(fd, BLKFLSBUF, 0); /* make sure we read current data */
-
-
 	if (lseek64(fd, sb_offset << 9, 0)< 0LL) {
 		if (devname)
 			pr_err("Cannot seek to superblock on %s: %s\n",