eCryptfs: Flush dirty pages in setattr

After 57db4e8d73ef2b5e94a3f412108dff2576670a8a changed eCryptfs to
write-back caching, eCryptfs page writeback updates the lower inode
times due to the use of vfs_write() on the lower file.

To preserve inode metadata changes, such as 'cp -p' does with
utimensat(), we need to flush all dirty pages early in
ecryptfs_setattr() so that the user-updated lower inode metadata isn't
clobbered later in writeback.

https://bugzilla.kernel.org/show_bug.cgi?id=33372

Reported-by: Rocko <rockorequin@hotmail.com>
Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index 2c19d362d2d4..4d4cc6a90cd5 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -929,6 +929,12 @@ static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
                 }
         }
         mutex_unlock(&crypt_stat->cs_mutex);
+        if (S_ISREG(inode->i_mode)) {
+                rc = filemap_write_and_wait(inode->i_mapping);
+                if (rc)
+                        goto out;
+                fsstack_copy_attr_all(inode, lower_inode);
+        }
         memcpy(&lower_ia, ia, sizeof(lower_ia));
         if (ia->ia_valid & ATTR_FILE)
                 lower_ia.ia_file = ecryptfs_file_to_lower(ia->ia_file);