sdcard: direct I/O file access fix
If a file is opened in direct I/O mode (with O_DIRECT flag),
the read buffer addess must be aligned to memory page size
boundary. The Direct I/O is not needed for normal files,
however, some special hardware access (e.g. smart SD cards)
will not work without it.
Change-Id: I42babeee86dba1880fd23e2592fddd7060da3e20
diff --git a/sdcard/sdcard.c b/sdcard/sdcard.c
index 4722708..3bc8cd3 100644
--- a/sdcard/sdcard.c
+++ b/sdcard/sdcard.c
@@ -232,7 +232,7 @@
* buffer at the same time. This allows us to share the underlying storage. */
union {
__u8 request_buffer[MAX_REQUEST_SIZE];
- __u8 read_buffer[MAX_READ];
+ __u8 read_buffer[MAX_READ + PAGESIZE];
};
};
@@ -1218,6 +1218,7 @@
__u32 size = req->size;
__u64 offset = req->offset;
int res;
+ __u8 *read_buffer = (__u8 *) ((uintptr_t)(handler->read_buffer + PAGESIZE) & ~((uintptr_t)PAGESIZE-1));
/* Don't access any other fields of hdr or req beyond this point, the read buffer
* overlaps the request buffer and will clobber data in the request. This
@@ -1225,14 +1226,14 @@
TRACE("[%d] READ %p(%d) %u@%llu\n", handler->token,
h, h->fd, size, offset);
- if (size > sizeof(handler->read_buffer)) {
+ if (size > MAX_READ) {
return -EINVAL;
}
- res = pread64(h->fd, handler->read_buffer, size, offset);
+ res = pread64(h->fd, read_buffer, size, offset);
if (res < 0) {
return -errno;
}
- fuse_reply(fuse, unique, handler->read_buffer, res);
+ fuse_reply(fuse, unique, read_buffer, res);
return NO_STATUS;
}