linux-kernel - [PATCH v2 27/28] iomap: Support multi-page folios in invalidatepage

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Date:   Mon,  8 Nov 2021 04:05:50 +0000
From:   "Matthew Wilcox (Oracle)" <willy@...radead.org>
To:     "Darrick J . Wong " <djwong@...nel.org>
Cc:     "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
        Jens Axboe <axboe@...nel.dk>,
        Christoph Hellwig <hch@...radead.org>,
        Christoph Hellwig <hch@....de>
Subject: [PATCH v2 27/28] iomap: Support multi-page folios in invalidatepage

If we're punching a hole in a multi-page folio, we need to remove the
per-folio iomap data as the folio is about to be split and each page will
need its own.  If a dirty folio is only partially-uptodate, the iomap
data contains the information about which blocks cannot be written back,
so assert that a dirty folio is fully uptodate.

Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
Reviewed-by: Christoph Hellwig <hch@....de>
Reviewed-by: Darrick J. Wong <djwong@...nel.org>
---
 fs/iomap/buffered-io.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 6830e4c15c61..265c7f8e7134 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -470,13 +470,18 @@ void iomap_invalidate_folio(struct folio *folio, size_t offset, size_t len)
 	trace_iomap_invalidatepage(folio->mapping->host, offset, len);
 
 	/*
-	 * If we're invalidating the entire page, clear the dirty state from it
-	 * and release it to avoid unnecessary buildup of the LRU.
+	 * If we're invalidating the entire folio, clear the dirty state
+	 * from it and release it to avoid unnecessary buildup of the LRU.
 	 */
 	if (offset == 0 && len == folio_size(folio)) {
 		WARN_ON_ONCE(folio_test_writeback(folio));
 		folio_cancel_dirty(folio);
 		iomap_page_release(folio);
+	} else if (folio_test_multi(folio)) {
+		/* Must release the iop so the page can be split */
+		WARN_ON_ONCE(!folio_test_uptodate(folio) &&
+			     folio_test_dirty(folio));
+		iomap_page_release(folio);
 	}
 }
 EXPORT_SYMBOL_GPL(iomap_invalidate_folio);
-- 
2.33.0