From: Jiro SEKIBA <jir@unicus.jp>
Date: Sat, 20 Feb 2010 10:47:49 +0000 (+0900)
Subject: nilfs2: add reader's lock for cno in nilfs_ioctl_sync
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=0d561f12b490dd2b993d73112d3297007688e6df;p=deliverable%2Flinux.git

nilfs2: add reader's lock for cno in nilfs_ioctl_sync

This adds reader's lock for the_nilfs->cno in nilfs_ioctl_sync,
for the_nilfs->cno should be proctected by segctor_sem when reading.

Signed-off-by: Jiro SEKIBA <jir@unicus.jp>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
---

diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
index 8e5cad020c30..313d0a21da48 100644
--- a/fs/nilfs2/ioctl.c
+++ b/fs/nilfs2/ioctl.c
@@ -601,13 +601,17 @@ static int nilfs_ioctl_sync(struct inode *inode, struct file *filp,
 {
 	__u64 cno;
 	int ret;
+	struct the_nilfs *nilfs;
 
 	ret = nilfs_construct_segment(inode->i_sb);
 	if (ret < 0)
 		return ret;
 
 	if (argp != NULL) {
-		cno = NILFS_SB(inode->i_sb)->s_nilfs->ns_cno - 1;
+		nilfs = NILFS_SB(inode->i_sb)->s_nilfs;
+		down_read(&nilfs->ns_segctor_sem);
+		cno = nilfs->ns_cno - 1;
+		up_read(&nilfs->ns_segctor_sem);
 		if (copy_to_user(argp, &cno, sizeof(cno)))
 			return -EFAULT;
 	}