ceph: fix recursion between ceph_set_acl() and __ceph_setattr()
authorYan, Zheng <zyan@redhat.com>
Wed, 19 Apr 2017 02:01:48 +0000 (10:01 +0800)
committerIlya Dryomov <idryomov@gmail.com>
Tue, 25 Apr 2017 19:08:26 +0000 (21:08 +0200)
commit8179a101eb5f4ef0ac9a915fcea9a9d3109efa90
treea0b54dda13c9eea85dad15d40d8e345aa2bcc68d
parent5a7ad1146caa895ad718a534399e38bd2ba721b7
ceph: fix recursion between ceph_set_acl() and __ceph_setattr()

ceph_set_acl() calls __ceph_setattr() if the setacl operation needs
to modify inode's i_mode. __ceph_setattr() updates inode's i_mode,
then calls posix_acl_chmod().

The problem is that __ceph_setattr() calls posix_acl_chmod() before
sending the setattr request. The get_acl() call in posix_acl_chmod()
can trigger a getxattr request. The reply of the getxattr request
can restore inode's i_mode to its old value. The set_acl() call in
posix_acl_chmod() sees old value of inode's i_mode, so it calls
__ceph_setattr() again.

Cc: stable@vger.kernel.org # needs backporting for < 4.9
Link: http://tracker.ceph.com/issues/19688
Reported-by: Jerry Lee <leisurelysw24@gmail.com>
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Tested-by: Luis Henriques <lhenriques@suse.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
fs/ceph/inode.c