osd: set r only if succeed in FillInVerifyExtent

When read failed, ret can be taken as data len in FillInVerifyExtent, which should be avoided.
It may cause errors in crc repair or retry read because of the data len. In my case, we use FillInVerifyExtent for EC read,
when meet -EIO，we will try crc repair, which need read data from other shard accrding to data len.
And I meet assert in ECBackend.cc (loc: line 2288 ceph_assert(range.first != range.second) ), But it seems master branch not support EC crc repair.
In shot, when reuse the readop may cause unpredictable error.

Fixes: https://tracker.ceph.com/issues/51115
Signed-off-by: yanqiang-ux <yanqiang_ux@163.com>
(cherry picked from commit 127745161fbcdee06b2dfa8464270c3934bcd06a)

diff --git a/src/osd/PrimaryLogPG.cc b/src/osd/PrimaryLogPG.cc
index 339b262b60b04942ad0ec441ccc2bda9ade132cd..ec9a5d37c74e7be9e5fd961ac84abad6cfe3a11c 100644 (file)
--- a/src/osd/PrimaryLogPG.cc
+++ b/src/osd/PrimaryLogPG.cc
@@ -5187,11 +5187,11 @@ struct FillInVerifyExtent : public Context {
     r(r), rval(rv), outdatap(blp), maybe_crc(mc),
     size(size), osd(osd), soid(soid), flags(flags) {}
   void finish(int len) override {
-    *r = len;
     if (len < 0) {
       *rval = len;
       return;
     }
+    *r = len;
     *rval = 0;
 
     // whole object?  can we verify the checksum?