mapping_set_error(mapping, -EIO);
                return -EIO; /* we're in a forced umount, don't write! */
        }
-       if (fsc->mount_options->wsize && fsc->mount_options->wsize < wsize)
+       if (fsc->mount_options->wsize < wsize)
                wsize = fsc->mount_options->wsize;
-       if (wsize < PAGE_SIZE)
-               wsize = PAGE_SIZE;
        max_pages_ever = wsize >> PAGE_SHIFT;
 
        pagevec_init(&pvec, 0);
 
                        break;
                }
 
-               if (!write)
+               if (write)
+                       size = min_t(u64, size, fsc->mount_options->wsize);
+               else
                        size = min_t(u64, size, fsc->mount_options->rsize);
 
                len = size;
 
                break;
                /* misc */
        case Opt_wsize:
-               fsopt->wsize = intval;
+               if (intval < PAGE_SIZE || intval > CEPH_MAX_WRITE_SIZE)
+                       return -EINVAL;
+               fsopt->wsize = ALIGN(intval, PAGE_SIZE);
                break;
        case Opt_rsize:
                if (intval < PAGE_SIZE || intval > CEPH_MAX_READ_SIZE)
        fsopt->sb_flags = flags;
        fsopt->flags = CEPH_MOUNT_OPT_DEFAULT;
 
+       fsopt->wsize = CEPH_MAX_WRITE_SIZE;
        fsopt->rsize = CEPH_MAX_READ_SIZE;
        fsopt->rasize = CEPH_RASIZE_DEFAULT;
        fsopt->snapdir_name = kstrdup(CEPH_SNAPDIRNAME_DEFAULT, GFP_KERNEL);
 
 
 /* max size of osd read request, limited by libceph */
 #define CEPH_MAX_READ_SIZE              CEPH_MSG_MAX_DATA_LEN
+/* osd has a configurable limitaion of max write size.
+ * CEPH_MSG_MAX_DATA_LEN should be small enough. */
+#define CEPH_MAX_WRITE_SIZE            CEPH_MSG_MAX_DATA_LEN
 #define CEPH_RASIZE_DEFAULT             (8192*1024)    /* max readahead */
 #define CEPH_MAX_READDIR_DEFAULT        1024
 #define CEPH_MAX_READDIR_BYTES_DEFAULT  (512*1024)