linux-kernel - [PATCH v13 127/137] iomap: Support multi-page folios in invalidatepage

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Date:   Mon, 12 Jul 2021 04:06:51 +0100
From:   "Matthew Wilcox (Oracle)" <willy@...radead.org>
To:     linux-kernel@...r.kernel.org
Cc:     "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        linux-mm@...ck.org, linux-fsdevel@...r.kernel.org
Subject: [PATCH v13 127/137] iomap: Support multi-page folios in invalidatepage

If we're punching a hole in a multi-page folio, we need to remove the
per-page iomap data as the folio is about to be split and each page will
need its own.  This means that writepage can now come across a page with
no iop allocated, so remove the assertion that there is already one,
and just create one (with the uptodate bits set) if there isn't one.

Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
---
 fs/iomap/buffered-io.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index bd811b3dbe86..18a683cc5c2b 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -474,13 +474,17 @@ iomap_invalidatepage(struct page *page, unsigned int offset, unsigned int len)
 	trace_iomap_invalidatepage(folio->mapping->host, offset, len);
 
 	/*
-	 * If we are invalidating the entire page, clear the dirty state from it
-	 * and release it to avoid unnecessary buildup of the LRU.
+	 * If we are 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_writeback(folio));
 		folio_cancel_dirty(folio);
 		iomap_page_release(folio);
+	} else if (folio_multi(folio)) {
+		/* Must release the iop so the page can be split */
+		WARN_ON_ONCE(!folio_uptodate(folio) && folio_dirty(folio));
+		iomap_page_release(folio);
 	}
 }
 EXPORT_SYMBOL_GPL(iomap_invalidatepage);
@@ -1300,7 +1304,7 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
 		struct writeback_control *wbc, struct inode *inode,
 		struct folio *folio, loff_t end_pos)
 {
-	struct iomap_page *iop = to_iomap_page(folio);
+	struct iomap_page *iop = iomap_page_create(inode, folio);
 	struct iomap_ioend *ioend, *next;
 	unsigned len = i_blocksize(inode);
 	unsigned nblocks = i_blocks_per_folio(inode, folio);
@@ -1308,7 +1312,6 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
 	int error = 0, count = 0, i;
 	LIST_HEAD(submit_list);
 
-	WARN_ON_ONCE(nblocks > 1 && !iop);
 	WARN_ON_ONCE(iop && atomic_read(&iop->write_bytes_pending) != 0);
 
 	/*
-- 
2.30.2