From: Gu Zheng <guz.fnst@cn.fujitsu.com>
Date: Mon, 29 Apr 2013 18:55:52 +0000 (-0700)
Subject: fs/block_dev.c: fix iov_shorten() criteria in blkdev_aio_read()
X-Git-Tag: firefly_0821_release~3680^2~531^2~2
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=6f8f5c260af67fed49fe14efc3ad1f69654c260e;p=firefly-linux-kernel-4.4.55.git

fs/block_dev.c: fix iov_shorten() criteria in blkdev_aio_read()

blkdev_aio_read() test 'size' to see if it is equal or greater than the
target count we request(iocb->ki_left).  If so there is no need to call
iov_shorten() to reduce number of segments and the iovec's length.  So the
judgement should be changed to 'if (size < iocb->ki_left)' instead.

Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/fs/block_dev.c b/fs/block_dev.c
index aea605c98ba6..dc7f9836fb5e 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1558,7 +1558,7 @@ static ssize_t blkdev_aio_read(struct kiocb *iocb, const struct iovec *iov,
 		return 0;
 
 	size -= pos;
-	if (size < INT_MAX)
+	if (size < iocb->ki_left)
 		nr_segs = iov_shorten((struct iovec *)iov, nr_segs, size);
 	return generic_file_aio_read(iocb, iov, nr_segs, pos);
 }