[PATCH] ceph: do not truncate pagecache if truncate size doesn't change

[xiubli@redhat.com]

From: Xiubo Li <xiubli@redhat.com>

In case truncating a file to a smaller sizeA, the sizeA will be kept
in truncate_size. And if truncate the file to a bigger sizeB, the
MDS will only increase the truncate_seq, but still using the sizeA as
the truncate_size.

So when filling the inode it will truncate the pagecache by using
truncate_sizeA again, which makes no sense and will trim the inocent
pages.

Signed-off-by: Xiubo Li <xiubli@redhat.com>
---
 fs/ceph/inode.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 1b4ce453d397..b4f784684e64 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -738,10 +738,11 @@ int ceph_fill_file_size(struct inode *inode, int issued,
 			 * don't hold those caps, then we need to check whether
 			 * the file is either opened or mmaped
 			 */
-			if ((issued & (CEPH_CAP_FILE_CACHE|
+			if (ci->i_truncate_size != truncate_size &&
+			    ((issued & (CEPH_CAP_FILE_CACHE|
 				       CEPH_CAP_FILE_BUFFER)) ||
 			    mapping_mapped(inode->i_mapping) ||
-			    __ceph_is_file_opened(ci)) {
+			    __ceph_is_file_opened(ci))) {
 				ci->i_truncate_pending++;
 				queue_trunc = 1;
 			}
-- 
2.27.0