linux-kernel - [PATCH 2/2] dio: simple cleanup for direct_io

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Date:	Tue, 11 Jan 2011 21:15:04 +0900
From:	Namhyung Kim <namhyung@...il.com>
To:	Alexander Viro <viro@...iv.linux.org.uk>
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] dio: simple cleanup for direct_io_worker()

Use DIV_ROUND_UP() and offset_in_page() to make code simpler.

Signed-off-by: Namhyung Kim <namhyung@...il.com>
---
 fs/direct-io.c |   13 ++++++++-----
 1 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/fs/direct-io.c b/fs/direct-io.c
index 8201c2558d85..7ba681412bd4 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -1020,16 +1020,19 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode,
 	for (seg = 0; seg < nr_segs; seg++) {
 		user_addr = (unsigned long)iov[seg].iov_base;
 		dio->pages_in_io +=
-			((user_addr+iov[seg].iov_len +PAGE_SIZE-1)/PAGE_SIZE
+			(DIV_ROUND_UP(user_addr + iov[seg].iov_len, PAGE_SIZE)
 				- user_addr/PAGE_SIZE);
 	}
 
 	for (seg = 0; seg < nr_segs; seg++) {
+		unsigned page_offset;
+
 		user_addr = (unsigned long)iov[seg].iov_base;
 		dio->size += bytes = iov[seg].iov_len;
+		page_offset = offset_in_page(user_addr);
 
 		/* Index into the first page of the first block */
-		dio->first_block_in_page = (user_addr & ~PAGE_MASK) >> blkbits;
+		dio->first_block_in_page = page_offset >> blkbits;
 		dio->final_block_in_request = dio->block_in_file +
 						(bytes >> blkbits);
 		/* Page fetching state */
@@ -1038,11 +1041,11 @@ direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode,
 		dio->curr_page = 0;
 
 		dio->total_pages = 0;
-		if (user_addr & (PAGE_SIZE-1)) {
+		if (page_offset) {
 			dio->total_pages++;
-			bytes -= PAGE_SIZE - (user_addr & (PAGE_SIZE - 1));
+			bytes -= PAGE_SIZE - page_offset;
 		}
-		dio->total_pages += (bytes + PAGE_SIZE - 1) / PAGE_SIZE;
+		dio->total_pages += DIV_ROUND_UP(bytes, PAGE_SIZE);
 		dio->curr_user_address = user_addr;
 	
 		ret = do_direct_IO(dio);
-- 
1.7.3.4.600.g982838b0

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