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Commit 80b435a3 authored by Arpad Horvath's avatar Arpad Horvath Committed by JP Abgrall
Browse files

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
parent d0307bee

sdcard/sdcard.c

+5 −4
Original line number Diff line number Diff line
@@ -232,7 +232,7 @@ struct fuse_handler { 
     * 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 @@ static int handle_read(struct fuse* fuse, struct fuse_handler* handler, 
    __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 @@ static int handle_read(struct fuse* fuse, struct fuse_handler* handler, 


    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;

}