ceph: try getting buffer capability for readahead/fadvise
For readahead/fadvise cases, caller of ceph_readpages does not
hold buffer capability. Pages can be added to page cache while
there is no buffer capability. This can cause data integrity
issue.
Signed-off-by: Yan, Zheng <zyan@redhat.com>
diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 4037b38..edb407f 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -2479,6 +2479,27 @@
ceph_check_caps(ci, CHECK_CAPS_AUTHONLY, NULL);
}
+int ceph_try_get_caps(struct ceph_inode_info *ci, int need, int want, int *got)
+{
+ int ret, err = 0;
+
+ BUG_ON(need & ~CEPH_CAP_FILE_RD);
+ BUG_ON(want & ~(CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO));
+ ret = ceph_pool_perm_check(ci, need);
+ if (ret < 0)
+ return ret;
+
+ ret = try_get_cap_refs(ci, need, want, 0, true, got, &err);
+ if (ret) {
+ if (err == -EAGAIN) {
+ ret = 0;
+ } else if (err < 0) {
+ ret = err;
+ }
+ }
+ return ret;
+}
+
/*
* Wait for caps, and take cap references. If we can't get a WR cap
* due to a small max_size, make sure we check_max_size (and possibly