os/filestore: fix result code if sanity check failed during copy_range

According to Linux Man Page, the lseek() system call returns -1 and
sets errno only if it indeed encouters some error.
The problem here is if lseek64() returns a positive answer, which
is not strictly equal to the expected answer however, then errno
may not be set and we return success instead, which is wrong.

This commit solves the above problem by checking against the returned
value of lseek64(), if -1 then we reset result code to errno, otherwise
we reset result code to -EINVAL to indicate that it is sanity check not
passed is the real relevant issue.

One more thing, as _do_copy_range() may return customized error code,
caller shall not redirect result code to errno on failure, which is
also shall be considered as wrong action.

Fixes: #14827
Signed-off-by: xie xingguo <xie.xingguo@zte.com.cn>

diff --git a/src/os/filestore/FileStore.cc b/src/os/filestore/FileStore.cc
index a35c781497779b433ec9793d9da2107f3e058c2a..581c72563f87db5baa3af3bb2ee18990b6423c11 100644 (file)
--- a/src/os/filestore/FileStore.cc
+++ b/src/os/filestore/FileStore.cc
@@ -3381,7 +3381,6 @@ int FileStore::_do_sparse_copy_range(int from, int to, uint64_t srcoff, uint64_t
     uint64_t it_off = miter->first - srcoff + dstoff;
     r = _do_copy_range(from, to, miter->first, miter->second, it_off, true);
     if (r < 0) {
-      r = -errno;
       derr << "FileStore::_do_copy_range: copy error at " << miter->first << "~" << miter->second
              << " to " << it_off << ", " << cpp_strerror(r) << dendl;
       break;
@@ -3470,13 +3469,19 @@ int FileStore::_do_copy_range(int from, int to, uint64_t srcoff, uint64_t len, u
 
     actual = ::lseek64(from, srcoff, SEEK_SET);
     if (actual != (int64_t)srcoff) {
-      r = -errno;
+      if (actual < 0)
+        r = -errno;
+      else
+        r = -EINVAL;
       derr << "lseek64 to " << srcoff << " got " << cpp_strerror(r) << dendl;
       return r;
     }
     actual = ::lseek64(to, dstoff, SEEK_SET);
     if (actual != (int64_t)dstoff) {
-      r = -errno;
+      if (actual < 0)
+        r = -errno;
+      else
+        r = -EINVAL;
       derr << "lseek64 to " << dstoff << " got " << cpp_strerror(r) << dendl;
       return r;
     }