fuse: lock inode unconditionally in fuse_fallocate()

stable inclusion
from stable-v5.10.157
commit 4801672fb076d546c67504ec9810a3a467e91768
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7MU59

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4801672fb076d546c67504ec9810a3a467e91768



--------------------------------

commit 44361e8c upstream.

file_modified() must be called with inode lock held.  fuse_fallocate()
didn't lock the inode in case of just FALLOC_KEEP_SIZE flags value, which
resulted in a kernel Warning in notify_change().

Lock the inode unconditionally, like all other fallocate implementations
do.

Reported-by: Pengfei Xu <pengfei.xu@intel.com>
Reported-and-tested-by:  <syzbot+462da39f0667b357c4b6@syzkaller.appspotmail.com>
Fixes: 4a6f278d ("fuse: add file_modified() to fallocate")
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>