From: Dmitry Monakhov <dmonakhov@sw.ru>

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 <dmonakhov@openvz.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 drivers/block/loop.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff -puN drivers/block/loop.c~deny-partial-write-for-loop-dev-fd drivers/block/loop.c
--- a/drivers/block/loop.c~deny-partial-write-for-loop-dev-fd
+++ a/drivers/block/loop.c
@@ -245,10 +245,8 @@ static int do_lo_send_aops(struct loop_d
 
 		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;
_