[PATCH AUTOSEL 4.14 19/27] NFS: Don't use page_file_mapping after removing the page

Sasha Levin
2019-03-11T20:03:00Z

From: Benjamin Coddington <bcodding@redhat.com>

[ Upstream commit d2ceb7e57086750ea6198a31fd942d98099a0786 ]

If nfs_page_async_flush() removes the page from the mapping, then we can't
use page_file_mapping() on it as nfs_updatepate() is wont to do when
receiving an error. Instead, push the mapping to the stack before the page
is possibly truncated.

Fixes: 8fc75bed96bb ("NFS: Fix up return value on fatal errors in nfs_page_async_flush()")
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/nfs/write.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 2d956a7d5378..50ed3944d183 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -236,9 +236,9 @@ static void nfs_grow_file(struct page *page, unsigned int offset, unsigned int c
}

/* A writeback failed: mark the page as bad, and invalidate the page cache */
-static void nfs_set_pageerror(struct page *page)
+static void nfs_set_pageerror(struct address_space *mapping)
{
- nfs_zap_mapping(page_file_mapping(page)->host, page_file_mapping(page));
+ nfs_zap_mapping(mapping->host, mapping);
}

/*
@@ -994,7 +994,7 @@ static void nfs_write_completion(struct nfs_pgio_header *hdr)
nfs_list_remove_request(req);
if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) &&
(hdr->good_bytes < bytes)) {
- nfs_set_pageerror(req->wb_page);
+ nfs_set_pageerror(page_file_mapping(req->wb_page));
nfs_context_set_write_error(req->wb_context, hdr->error);
goto remove_req;
}
@@ -1330,7 +1330,8 @@ int nfs_updatepage(struct file *file, struct page *page,
unsigned int offset, unsigned int count)
{
struct nfs_open_context *ctx = nfs_file_open_context(file);
- struct inode *inode = page_file_mapping(page)->host;
+ struct address_space *mapping = page_file_mapping(page);
+ struct inode *inode = mapping->host;
int status = 0;

nfs_inc_stats(inode, NFSIOS_VFSUPDATEPAGE);
@@ -1348,7 +1349,7 @@ int nfs_updatepage(struct file *file, struct page *page,

status = nfs_writepage_setup(ctx, page, offset, count);
if (status < 0)
- nfs_set_pageerror(page);
+ nfs_set_pageerror(mapping);
else
__set_page_dirty_nobuffers(page);
out:
--
2.19.1