[PATCH 05/14] iomap: Support THPs in invalidatepage

From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
To: linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>, linux-mm@kvack.org
Subject: [PATCH 05/14] iomap: Support THPs in invalidatepage
Date: Wed, 14 Oct 2020 04:03:48 +0100	[thread overview]
Message-ID: <20201014030357.21898-6-willy@infradead.org> (raw)
In-Reply-To: <20201014030357.21898-1-willy@infradead.org>

If we're punching a hole in a THP, we need to remove the per-page
iomap data as the THP 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@infradead.org>
---
 fs/iomap/buffered-io.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 95ac66731297..4633ebd03a3f 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -60,6 +60,8 @@ iomap_page_create(struct inode *inode, struct page *page)
 	iop = kzalloc(struct_size(iop, uptodate, BITS_TO_LONGS(nr_blocks)),
 			GFP_NOFS | __GFP_NOFAIL);
 	spin_lock_init(&iop->uptodate_lock);
+	if (PageUptodate(page))
+		bitmap_fill(iop->uptodate, nr_blocks);
 	attach_page_private(page, iop);
 	return iop;
 }
@@ -494,10 +496,14 @@ iomap_invalidatepage(struct page *page, unsigned int offset, unsigned int 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 (offset == 0 && len == PAGE_SIZE) {
+	if (offset == 0 && len == thp_size(page)) {
 		WARN_ON_ONCE(PageWriteback(page));
 		cancel_dirty_page(page);
 		iomap_page_release(page);
+	} else if (PageTransHuge(page)) {
+		/* Punching a hole in a THP requires releasing the iop */
+		WARN_ON_ONCE(!PageUptodate(page) && PageDirty(page));
+		iomap_page_release(page);
 	}
 }
 EXPORT_SYMBOL_GPL(iomap_invalidatepage);
@@ -1363,14 +1369,13 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
 		struct writeback_control *wbc, struct inode *inode,
 		struct page *page, u64 end_offset)
 {
-	struct iomap_page *iop = to_iomap_page(page);
+	struct iomap_page *iop = iomap_page_create(inode, page);
 	struct iomap_ioend *ioend, *next;
 	unsigned len = i_blocksize(inode);
 	u64 file_offset; /* file offset of page */
 	int error = 0, count = 0, i;
 	LIST_HEAD(submit_list);
 
-	WARN_ON_ONCE(i_blocks_per_page(inode, page) > 1 && !iop);
 	WARN_ON_ONCE(iop && atomic_read(&iop->write_bytes_pending) != 0);
 
 	/*
@@ -1415,7 +1420,6 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
 			 */
 			if (wpc->ops->discard_page)
 				wpc->ops->discard_page(page);
-			ClearPageUptodate(page);
 			unlock_page(page);
 			goto done;
 		}
-- 
2.28.0

