[PATCH] generic/798: exclude nfs from cachestat dirty page reporting test

[Avinesh Kumar <avinesh.kumar@suse.com>]

From: Avinesh Kumar <avinesh.kumar@suse.com>

generic/798 checks cachestat() page cache dirty state between write and
fsync operations.

On NFS, the client flushes dirty pages to the server during close() to
enforce its close-to-open consistency model. Because the test uses separate
xfs_io invocations, the file is closed after writing, leaving pages already
clean by the time the subsequent cachestat command executes, causing the
test to fail.

- output mismatch (see /opt/xfstests/results//generic/798.out.bad)
    --- tests/generic/798.out	2026-08-20 05:25:39.000000000 -0400
    +++ /opt/xfstests/results//generic/798.out.bad	2026-08-21 12:30:39.831381108 -0400
    @@ -1,16 +1,16 @@
     QA output created by 798
     === Test with 1 pages ===
    -Cached: 1, Dirty: 1, Writeback: 0, Evicted: 0, Recently Evicted: 0
    +Cached: 1, Dirty: 0, Writeback: 0, Evicted: 0, Recently Evicted: 0
     Cached: 1, Dirty: 0, Writeback: 0, Evicted: 0, Recently Evicted: 0
     === Test with 2 pages ===
    -Cached: 2, Dirty: 2, Writeback: 0, Evicted: 0, Recently Evicted: 0
    ...

Exclude 'nfs' from running this test.

Signed-off-by: Avinesh Kumar <avinesh.kumar@suse.com>
---
 tests/generic/798 | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tests/generic/798 b/tests/generic/798
index 0fe37646..80b2acc9 100755
--- a/tests/generic/798
+++ b/tests/generic/798
@@ -16,6 +16,12 @@ _require_scratch
 _exclude_scratch_mount_option "dax"
 _exclude_scratch_mount_option "sync"
 
+# NFS flushes dirty data back to the server on close() as part of its
+# close-to-open cache consistency model, so a page written and closed in
+# one xfs_io invocation is no longer dirty by the time cachestat runs in
+# a later invocation.
+_exclude_fs nfs
+
 pagesize=$(_get_page_size)
 
 _scratch_mkfs > /dev/null
-- 
2.55.0