When AS_RELEASE_ALWAYS is set on a mapping, the ->release_folio() and
->invalidate_folio() calls should be invoked even if PG_private and
PG_private_2 aren't set.  This is used by netfslib to keep track of the
point above which reads can be skipped in favour of just zeroing pagecache
locally.

There are a couple of places in truncation in which invalidation is only
called when folio_has_private() is true.  Fix these to check
folio_needs_release() instead.

Without this, the generic/075 and generic/112 xfstests (both fsx-based
tests) fail with minimum folio size patches applied[1].

Fixes: b4fa966f03b7 ("mm, netfs, fscache: stop read optimisation when folio 
removed from pagecache")
Signed-off-by: David Howells <[email protected]>
cc: Matthew Wilcox (Oracle) <[email protected]>
cc: Pankaj Raghav <[email protected]>
cc: Jeff Layton <[email protected]>
cc: Marc Dionne <[email protected]>
cc: [email protected]
cc: [email protected]
cc: [email protected]
cc: [email protected]
Link: 
https://lore.kernel.org/r/[email protected]/ [1]
---
 mm/truncate.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/truncate.c b/mm/truncate.c
index 4d61fbdd4b2f..0668cd340a46 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -157,7 +157,7 @@ static void truncate_cleanup_folio(struct folio *folio)
        if (folio_mapped(folio))
                unmap_mapping_folio(folio);
 
-       if (folio_has_private(folio))
+       if (folio_needs_release(folio))
                folio_invalidate(folio, 0, folio_size(folio));
 
        /*
@@ -219,7 +219,7 @@ bool truncate_inode_partial_folio(struct folio *folio, 
loff_t start, loff_t end)
        if (!mapping_inaccessible(folio->mapping))
                folio_zero_range(folio, offset, length);
 
-       if (folio_has_private(folio))
+       if (folio_needs_release(folio))
                folio_invalidate(folio, offset, length);
        if (!folio_test_large(folio))
                return true;

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