[PATCH] jffs2: fix potential deadlock in jffs2_do_setattr

From: Liu Song
Date: Wed Oct 11 2017 - 21:01:14 EST


In jffs2_do_setattr, we hold two mutexes which are
A) c->alloc_sem
B) f->sem
If new_metadata is error, then we release mutexes in bad sequence
which could cause ABAB deadlock.
This patch adjusts release sequence which could avoid deadlock.

Signed-off-by: Liu Song <liu.song11@xxxxxxxxxx>
Reviewed-by: Jiang Biao <jiang.biao2@xxxxxxxxxx>
---
fs/jffs2/fs.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/jffs2/fs.c b/fs/jffs2/fs.c
index 76fa814..f998126 100644
--- a/fs/jffs2/fs.c
+++ b/fs/jffs2/fs.c
@@ -140,9 +140,9 @@ int jffs2_do_setattr (struct inode *inode, struct iattr *iattr)
kfree(mdata);

if (IS_ERR(new_metadata)) {
- jffs2_complete_reservation(c);
jffs2_free_raw_inode(ri);
mutex_unlock(&f->sem);
+ jffs2_complete_reservation(c);
return PTR_ERR(new_metadata);
}
/* It worked. Update the inode */
--
2.1.0.GIT