ci: exclude new open_by_handle tests added by xfstests v2026.10.15

The first CI run of xfstests v2026.10.15 failed 2 of 777 tests on the
overlay job: generic/756 and generic/777, both from the open_by_handle
family.  Both print

  open_by_handle(...) returned 116 incorrectly on a linked file!

for every live file, i.e. open_by_handle_at(2) fails with ESTALE on
handles of still-linked files.

Root cause is the same FUSE limitation that already excludes
generic/426, 467 and 477, now reached through a new kernel path:
kernel 7.0 on the Ubuntu 26.04 runners registers full FUSE
export_operations, so name_to_handle_at(2) always succeeds
(fuse_encode_fh encodes nodeid + generation).  That is all
_require_exportfs checks (open_by_handle -c only creates files and
encodes handles), so the tests are no longer skipped.  The actual tests
however drop the caches before decoding, and after eviction
fuse_fh_to_dentry() must ask the server: LOOKUP "." on the handle's
nodeid, which the kernel only does when the server negotiated
FUSE_EXPORT_SUPPORT at INIT.  Neither PassthroughFs nor OverlayFs sets
that flag (and neither answers "." lookups on non-root nodeids), so
every decode of an evicted inode returns ESTALE.

generic/756 is the 2024 rewrite of the 426/467 line (mount ID
verification variants), generic/777 is a connectable-handle variant of
477; xfstests special-cases virtiofs for the very same limitation
("virtiofs doesn't support open_by_handle_at(2) yet ... It requires
stable FUSE nodeids").  Exclude both, following the existing
open_by_handle precedent in the exclude lists.  Real export support
(FUSE_EXPORT_SUPPORT + "."-on-nodeid lookups) would be a feature of
its own and is left as future work.

Signed-off-by: Jiang Liu <gerry@linux.alibaba.com>

Author: jiangliu

tests/scripts/xfstests_overlay.exclude

@@ -21,4 +21,6 @@ generic/477 # Suppose to be FUSE compatibility issue: 'open_by_handle'
 generic/591 # Broken.
 generic/633 # Suppose to be FUSE compatibility issue.
 generic/697 # Suppose to be FUSE compatibility issue.
-generic/736
+generic/736
+generic/756 # Suppose to be FUSE compatibility issue: 'open_by_handle'
+generic/777 # Suppose to be FUSE compatibility issue: 'open_by_handle'

tests/scripts/xfstests_pathr.exclude

@@ -9,4 +9,6 @@ generic/471
 generic/477
 generic/591
 generic/633
-generic/736
+generic/736
+generic/756
+generic/777