deny partial write for loop dev fd

Partial write can be easily supported by LO_CRYPT_NONE mode, but it is not
easy in LO_CRYPT_CRYPTOAPI case, because of its block nature.  I don't know
who still used cryptoapi, but theoretically it is possible.  So let's leave
things as they are.  Loop device doesn't support partial write before
Nick's "write_begin/write_end" patch set, and let's it behave the same way
after.

Signed-off-by: Dmitriy Monakhov <[email protected]>
Cc: Nick Piggin <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index a5f993ac28ddce4e4bf670b06ebc8c321011bdc3..e5a051577a5e617008f263b8cb5c9f914e1fe6a7 100644 (file)
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -245,10 +245,8 @@ static int do_lo_send_aops(struct loop_device *lo, struct bio_vec *bvec,
 
                ret = pagecache_write_end(file, mapping, pos, size, copied,
                                                        page, fsdata);
-               if (ret < 0)
+               if (ret < 0 || ret != copied)
                        goto fail;
-               if (ret < copied)
-                       copied = ret;
 
                if (unlikely(transfer_result))
                        goto fail;