From: Xiubo Li <xiubli@redhat.com>
Date: Fri, 8 Oct 2021 16:23:58 +0800
Subject: ceph: ignore the truncate when size won't change with Fx caps issued
Git-commit: e90334e89b0c3caa64213ba80fbbc053c7975c66
Patch-mainline: v5.16-rc1
References: jsc#SES-1880

If the new size is the same as the current size, the MDS will do nothing
but change the mtime/atime. POSIX doesn't mandate that the filesystems
must update them in this case, so just ignore it instead.

Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Acked-by: Luis Henriques <lhenriques@suse.com>
---
 fs/ceph/inode.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index c22c0676090f..e3322fcb2e8d 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -2103,12 +2103,14 @@ int __ceph_setattr(struct inode *inode, struct iattr *attr)
 		loff_t isize = i_size_read(inode);
 
 		dout("setattr %p size %lld -> %lld\n", inode, isize, attr->ia_size);
-		if ((issued & CEPH_CAP_FILE_EXCL) && attr->ia_size > isize) {
-			i_size_write(inode, attr->ia_size);
-			inode->i_blocks = calc_inode_blocks(attr->ia_size);
-			ci->i_reported_size = attr->ia_size;
-			dirtied |= CEPH_CAP_FILE_EXCL;
-			ia_valid |= ATTR_MTIME;
+		if ((issued & CEPH_CAP_FILE_EXCL) && attr->ia_size >= isize) {
+			if (attr->ia_size > isize) {
+				i_size_write(inode, attr->ia_size);
+				inode->i_blocks = calc_inode_blocks(attr->ia_size);
+				ci->i_reported_size = attr->ia_size;
+				dirtied |= CEPH_CAP_FILE_EXCL;
+				ia_valid |= ATTR_MTIME;
+			}
 		} else if ((issued & CEPH_CAP_FILE_SHARED) == 0 ||
 			   attr->ia_size != isize) {
 			req->r_args.setattr.size = cpu_to_le64(attr->ia_size);