kclient: zero leftovers for partial page write

diff --git a/src/kernel/addr.c b/src/kernel/addr.c
index b1bef72f5f249d093d175d0147dc75534875c2f3..432fba5db8a369a27684c107082009cae0e16d90 100644 (file)
--- a/src/kernel/addr.c
+++ b/src/kernel/addr.c
@@ -401,6 +401,7 @@ static int ceph_write_begin(struct file *file, struct address_space *mapping,
        pgoff_t index = pos >> PAGE_CACHE_SHIFT;
        loff_t page_off = pos & PAGE_MASK;
        int pos_in_page = pos & ~PAGE_MASK;
+       int end_in_page = pos_in_page + len;
        loff_t i_size;
        int r;
 
@@ -424,7 +425,7 @@ static int ceph_write_begin(struct file *file, struct address_space *mapping,
        i_size = inode->i_size;   /* caller holds i_mutex */
        if (page_off >= i_size ||
            (pos_in_page == 0 && (pos+len) >= i_size)) {
-               simple_prepare_write(file, page, pos_in_page, pos_in_page+len);
+               simple_prepare_write(file, page, pos_in_page, end_in_page);
                return 0;
        }
 
@@ -437,12 +438,21 @@ static int ceph_write_begin(struct file *file, struct address_space *mapping,
        if (r < 0)
                return r;
        if (r < pos_in_page) {
-               /* we didn't read up to our write start pos, zero the gap */
                void *kaddr = kmap_atomic(page, KM_USER1);
+               dout(20, "write_begin zeroing pre %d~%d\n", r, pos_in_page-r);
                memset(kaddr+r, 0, pos_in_page-r);
                flush_dcache_page(page);
                kunmap_atomic(kaddr, KM_USER1);
        }
+       end_in_page = pos_in_page + len;
+       if (end_in_page < PAGE_SIZE && r < PAGE_SIZE) {
+               void *kaddr = kmap_atomic(page, KM_USER1);
+               dout(20, "write_begin zeroing post %d~%d\n", end_in_page,
+                    (int)PAGE_SIZE - end_in_page);
+               memset(kaddr+end_in_page, 0, PAGE_SIZE-end_in_page);
+               flush_dcache_page(page);
+               kunmap_atomic(kaddr, KM_USER1);
+       }
        return 0;
 }