linux-ext4 - [PATCH v2] ext4: Create helper function for EXT4_IO_END_UNWRITTEN and i_aiodio

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Date:	Fri, 30 Sep 2011 17:41:56 +0800
From:	Tao Ma <tm@....ma>
To:	linux-ext4@...r.kernel.org
Cc:	Eric Sandeen <sandeen@...hat.com>
Subject: [PATCH v2] ext4: Create helper function for EXT4_IO_END_UNWRITTEN and i_aiodio_unwritten.

From: Tao Ma <boyu.mt@...bao.com>

EXT4_IO_END_UNWRITTEN flag set and the increase of i_aiodio_unwritten
should be done simultaneously since ext4_end_io_nolock always clear the
flag and decrease the counter in the same time.

We have found some bugs that the flag is set while leaving
i_aiodio_unwritten unchanged(commit 32c80b32c053d). So this patch just tries
to create a helper function to wrap them to avoid any future bug.
The idea is inspired by Eric.

Cc: Eric Sandeen <sandeen@...hat.com>
Signed-off-by: Tao Ma <boyu.mt@...bao.com>
---
This patch is based on another bug fix which hasn't been merged yet.
http://marc.info/?l=linux-ext4&m=131598536608613&w=2

 fs/ext4/ext4.h    |    9 +++++++++
 fs/ext4/extents.c |   18 ++++++------------
 fs/ext4/inode.c   |    5 +----
 fs/ext4/page-io.c |    6 ++----
 4 files changed, 18 insertions(+), 20 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 4cb030c..a9325f5 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1241,6 +1241,15 @@ static inline int ext4_valid_inum(struct super_block *sb, unsigned long ino)
 		 ino <= le32_to_cpu(EXT4_SB(sb)->s_es->s_inodes_count));
 }
 
+static inline void ext4_set_io_unwritten_flag(struct inode *inode,
+					      struct ext4_io_end *io_end)
+{
+	if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
+		io_end->flag |= EXT4_IO_END_UNWRITTEN;
+		atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten);
+	}
+}
+
 /*
  * Inode dynamic state flags
  */
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 8f23589..31750af 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3190,12 +3190,9 @@ ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
 		 * that this IO needs to conversion to written when IO is
 		 * completed
 		 */
-		if (io) {
-			if (!(io->flag & EXT4_IO_END_UNWRITTEN)) {
-				io->flag = EXT4_IO_END_UNWRITTEN;
-				atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten);
-			}
-		} else
+		if (io)
+			ext4_set_io_unwritten_flag(inode, io);
+		else
 			ext4_set_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
 		if (ext4_should_dioread_nolock(inode))
 			map->m_flags |= EXT4_MAP_UNINIT;
@@ -3574,12 +3571,9 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
 		 * that we need to perform conversion when IO is done.
 		 */
 		if ((flags & EXT4_GET_BLOCKS_PRE_IO)) {
-			if (io) {
-				if (!(io->flag & EXT4_IO_END_UNWRITTEN)) {
-					io->flag = EXT4_IO_END_UNWRITTEN;
-					atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten);
-				}
-			} else
+			if (io)
+				ext4_set_io_unwritten_flag(inode, io);
+			else
 				ext4_set_inode_state(inode,
 						     EXT4_STATE_DIO_UNWRITTEN);
 		}
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 4b37501..5d6fc9b 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2685,10 +2685,7 @@ static void ext4_end_io_buffer_write(struct buffer_head *bh, int uptodate)
 	 * but being more careful is always safe for the future change.
 	 */
 	inode = io_end->inode;
-	if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
-		io_end->flag |= EXT4_IO_END_UNWRITTEN;
-		atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten);
-	}
+	ext4_set_io_unwritten_flag(inode, io_end);
 
 	/* Add the io_end to per-inode completed io list*/
 	spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags);
diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 92f38ee..f5eec5e 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -350,10 +350,8 @@ submit_and_retry:
 	if ((io_end->num_io_pages >= MAX_IO_PAGES) &&
 	    (io_end->pages[io_end->num_io_pages-1] != io_page))
 		goto submit_and_retry;
-	if (buffer_uninit(bh) && !(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
-		io_end->flag |= EXT4_IO_END_UNWRITTEN;
-		atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten);
-	}
+	if (buffer_uninit(bh))
+		ext4_set_io_unwritten_flag(inode, io_end);
 	io->io_end->size += bh->b_size;
 	io->io_next_block++;
 	ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
-- 
1.7.1

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