[PATCH 02/27] afs: Fix page overput in afs_fill_page()

From	David Howells <dhowells@redhat.com>
Newsgroups	linux.kernel
Subject	[PATCH 02/27] afs: Fix page overput in afs_fill_page()
Date	2017-03-09 20:10 +0100
Message-ID	<tjbBM-10C-31@gated-at.bofh.it> (permalink)
References	<tjbs6-I0-7@gated-at.bofh.it>
Organization	Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903

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afs_fill_page() loads the page it wants to fill into the afs_read request
without incrementing its refcount - but then calls afs_put_read() to clean
up afterwards, which then releases a ref on the page.

Fix this by getting a ref on the page before calling
afs_vnode_fetch_data().

This causes sync after a write to hang in afs_writepages_region() because
find_get_pages_tag() gets confused and doesn't return.

Fixes: 196ee9cd2d04 ("afs: Make afs_fs_fetch_data() take a list of pages")
Reported-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Marc Dionne <marc.dionne@auristor.com>
---

 fs/afs/write.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/afs/write.c b/fs/afs/write.c
index e919e64cd4e0..3ac52f6a96ff 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -101,6 +101,7 @@ static int afs_fill_page(struct afs_vnode *vnode, struct key *key,
 	req->pos = pos;
 	req->nr_pages = 1;
 	req->pages[0] = page;
+	get_page(page);
 
 	i_size = i_size_read(&vnode->vfs_inode);
 	if (pos + PAGE_SIZE > i_size)

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[PATCH 01/27] afs: Fix missing put_page() David Howells <dhowells@redhat.com> - 2017-03-09 20:10 +0100
  [PATCH 02/27] afs: Fix page overput in afs_fill_page() David Howells <dhowells@redhat.com> - 2017-03-09 20:10 +0100

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