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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 01/14] fs: Support THPs in vfs_dedupe_file_range
Date: Wed, 14 Oct 2020 04:03:44 +0100	[thread overview]
Message-ID: <20201014030357.21898-2-willy@infradead.org> (raw)
In-Reply-To: <20201014030357.21898-1-willy@infradead.org>

We may get tail pages returned from vfs_dedupe_get_page().  If we do,
we have to call page_mapping() instead of dereferencing page->mapping
directly.  We may also deadlock trying to lock the page twice if they're
subpages of the same THP, so compare the head pages instead.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 fs/read_write.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/read_write.c b/fs/read_write.c
index 19f5c4bf75aa..ead675fef582 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1604,6 +1604,8 @@ static struct page *vfs_dedupe_get_page(struct inode *inode, loff_t offset)
  */
 static void vfs_lock_two_pages(struct page *page1, struct page *page2)
 {
+	page1 = thp_head(page1);
+	page2 = thp_head(page2);
 	/* Always lock in order of increasing index. */
 	if (page1->index > page2->index)
 		swap(page1, page2);
@@ -1616,6 +1618,8 @@ static void vfs_lock_two_pages(struct page *page1, struct page *page2)
 /* Unlock two pages, being careful not to unlock the same page twice. */
 static void vfs_unlock_two_pages(struct page *page1, struct page *page2)
 {
+	page1 = thp_head(page1);
+	page2 = thp_head(page2);
 	unlock_page(page1);
 	if (page1 != page2)
 		unlock_page(page2);
@@ -1670,8 +1674,8 @@ static int vfs_dedupe_file_range_compare(struct inode *src, loff_t srcoff,
 		 * someone is invalidating pages on us and we lose.
 		 */
 		if (!PageUptodate(src_page) || !PageUptodate(dest_page) ||
-		    src_page->mapping != src->i_mapping ||
-		    dest_page->mapping != dest->i_mapping) {
+		    page_mapping(src_page) != src->i_mapping ||
+		    page_mapping(dest_page) != dest->i_mapping) {
 			same = false;
 			goto unlock;
 		}
-- 
2.28.0


  reply	other threads:[~2020-10-14  9:21 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-14  3:03 [PATCH 00/14] Transparent Huge Page support for XFS Matthew Wilcox (Oracle)
2020-10-14  3:03 ` Matthew Wilcox (Oracle) [this message]
2020-10-14 16:12   ` [PATCH 01/14] fs: Support THPs in vfs_dedupe_file_range Darrick J. Wong
2020-10-14 17:16     ` Matthew Wilcox
2020-10-14  3:03 ` [PATCH 02/14] fs: Make page_mkwrite_check_truncate thp-aware Matthew Wilcox (Oracle)
2020-10-14 16:17   ` Darrick J. Wong
2020-10-14 17:23     ` Matthew Wilcox
2020-10-14  3:03 ` [PATCH 03/14] iomap: Support THPs in BIO completion path Matthew Wilcox (Oracle)
2020-10-15  9:50   ` Christoph Hellwig
2020-10-14  3:03 ` [PATCH 04/14] iomap: Support THPs in iomap_adjust_read_range Matthew Wilcox (Oracle)
2020-10-15  9:50   ` Christoph Hellwig
2020-10-14  3:03 ` [PATCH 05/14] iomap: Support THPs in invalidatepage Matthew Wilcox (Oracle)
2020-10-14 16:33   ` Darrick J. Wong
2020-10-14 17:26     ` Matthew Wilcox
2020-10-14 20:00       ` Brian Foster
2020-10-14  3:03 ` [PATCH 06/14] iomap: Support THPs in iomap_is_partially_uptodate Matthew Wilcox (Oracle)
2020-10-14  3:03 ` [PATCH 07/14] iomap: Support THPs in readpage Matthew Wilcox (Oracle)
2020-10-14 16:39   ` Darrick J. Wong
2020-10-14 17:35     ` Matthew Wilcox
2020-10-14  3:03 ` [PATCH 08/14] iomap: Support THPs in readahead Matthew Wilcox (Oracle)
2020-10-15  9:52   ` Christoph Hellwig
2020-10-14  3:03 ` [PATCH 09/14] iomap: Change iomap_write_begin calling convention Matthew Wilcox (Oracle)
2020-10-14 16:47   ` Darrick J. Wong
2020-10-14 17:41     ` Matthew Wilcox
2020-10-14 18:08       ` Matthew Wilcox
2020-10-14  3:03 ` [PATCH 10/14] iomap: Handle THPs when writing to pages Matthew Wilcox (Oracle)
2020-10-14  3:03 ` [PATCH 11/14] iomap: Support THP writeback Matthew Wilcox (Oracle)
2020-10-14  3:03 ` [PATCH 12/14] iomap: Inline data shouldn't see THPs Matthew Wilcox (Oracle)
2020-10-14  3:03 ` [PATCH 13/14] iomap: Handle tail pages in iomap_page_mkwrite Matthew Wilcox (Oracle)
2020-10-14  3:03 ` [PATCH 14/14] xfs: Support THPs Matthew Wilcox (Oracle)
2020-10-14 16:51   ` Darrick J. Wong
2020-10-14 17:30     ` Matthew Wilcox

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