[PATCH] deny partial write for loop dev fd

[Dmitriy 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>
---
 drivers/block/loop.c |    4 +---
 1 files changed, 1 insertions(+), 3 deletions(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 4bab9b1..de122f3 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -244,10 +244,8 @@ 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;
-- 
1.5.2