[PATCH] nilfs2: add reader's lock for cno in nilfs_ioctl_sync

[Jiro SEKIBA]

Hi,

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 <j...@unicus.jp>
---
 fs/nilfs2/ioctl.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
index d6b2b83..32d5103 100644
--- a/fs/nilfs2/ioctl.c
+++ b/fs/nilfs2/ioctl.c
@@ -575,13 +575,17 @@ 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;
        }
-- 
1.5.6.5



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