The patch titled
Subject: fs/iomap.c: get/put the page in iomap_page_create/release()
has been added to the -mm tree. Its filename is
iomap-get-put-the-page-in-iomap_page_create-release.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/iomap-get-put-the-page-in-iomap_page_create-release.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/iomap-get-put-the-page-in-iomap_page_create-release.patch
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------------------------------------------------------
From: Piotr Jaroszynski <pjaroszynski@xxxxxxxxxx>
Subject: fs/iomap.c: get/put the page in iomap_page_create/release()
migrate_page_move_mapping() expects pages with private data set to have a
page_count elevated by 1. This is what used to happen for xfs through the
buffer_heads code before the switch to iomap in commit 82cb14175e7d ("xfs:
add support for sub-pagesize writeback without buffer_heads"). Not having
the count elevated causes move_pages() to fail on memory mapped files
coming from xfs.
Make iomap compatible with the migrate_page_move_mapping() assumption by
elevating the page count as part of iomap_page_create() and lowering it in
iomap_page_release().
Link: http://lkml.kernel.org/r/20181115184140.1388751-1-pjaroszynski@xxxxxxxxxx
Fixes: 82cb14175e7d ("xfs: add support for sub-pagesize writeback without buffer_heads")
Signed-off-by: Piotr Jaroszynski <pjaroszynski@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Cc: William Kucharski <william.kucharski@xxxxxxxxxx>
Cc: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Cc: Brian Foster <bfoster@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/iomap.c | 7 +++++++
1 file changed, 7 insertions(+)
--- a/fs/iomap.c~iomap-get-put-the-page-in-iomap_page_create-release
+++ a/fs/iomap.c
@@ -116,6 +116,12 @@ iomap_page_create(struct inode *inode, s
atomic_set(&iop->read_count, 0);
atomic_set(&iop->write_count, 0);
bitmap_zero(iop->uptodate, PAGE_SIZE / SECTOR_SIZE);
+
+ /*
+ * migrate_page_move_mapping() assumes that pages with private data have
+ * their count elevated by 1.
+ */
+ get_page(page);
set_page_private(page, (unsigned long)iop);
SetPagePrivate(page);
return iop;
@@ -132,6 +138,7 @@ iomap_page_release(struct page *page)
WARN_ON_ONCE(atomic_read(&iop->write_count));
ClearPagePrivate(page);
set_page_private(page, 0);
+ put_page(page);
kfree(iop);
}
_
Patches currently in -mm which might be from pjaroszynski@xxxxxxxxxx are
iomap-get-put-the-page-in-iomap_page_create-release.patch
