ext4: Fix to read empty directory blocks correctly in 64k

[~andy/linux] / fs / bio.c

diff --git a/fs/bio.c b/fs/bio.c
index 356e7423b923e25f4dec9c5a5681221d68c0d1cd..062299acbccddc2d8f808d6cb85722cdd9ef6d09 100644 (file)
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -788,6 +788,7 @@ struct bio *bio_copy_user_iov(struct request_queue *q,
        int i, ret;
        int nr_pages = 0;
        unsigned int len = 0;
+       unsigned int offset = map_data ? map_data->offset & ~PAGE_MASK : 0;
 
        for (i = 0; i < iov_count; i++) {
                unsigned long uaddr;
@@ -814,12 +815,16 @@ struct bio *bio_copy_user_iov(struct request_queue *q,
        bio->bi_rw |= (!write_to_vm << BIO_RW);
 
        ret = 0;
-       i = 0;
-       if (map_data)
+
+       if (map_data) {
                nr_pages = 1 << map_data->page_order;
+               i = map_data->offset / PAGE_SIZE;
+       }
        while (len) {
                unsigned int bytes = PAGE_SIZE;
 
+               bytes -= offset;
+
                if (bytes > len)
                        bytes = len;
 
@@ -841,10 +846,11 @@ struct bio *bio_copy_user_iov(struct request_queue *q,
                        }
                }
 
-               if (bio_add_pc_page(q, bio, page, bytes, 0) < bytes)
+               if (bio_add_pc_page(q, bio, page, bytes, offset) < bytes)
                        break;
 
                len -= bytes;
+               offset = 0;
        }
 
        if (ret)
@@ -853,7 +859,7 @@ struct bio *bio_copy_user_iov(struct request_queue *q,
        /*
         * success
         */
-       if (!write_to_vm) {
+       if (!write_to_vm && (!map_data || !map_data->null_mapped)) {
                ret = __bio_copy_iov(bio, bio->bi_io_vec, iov, iov_count, 0, 0);
                if (ret)
                        goto cleanup;