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Date:   Thu, 2 Jan 2020 16:04:26 +0800
From:   Murphy Zhou <jencce.kernel@gmail.com>
To:     linux-nfs@vger.kernel.org
Subject: [PATCH] fs/nfs, swapon: check holes in swapfile
Message-ID: <20200102080426.byzq4rrdilr2qxx6@xzhoux.usersys.redhat.com>
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Sender: linux-nfs-owner@vger.kernel.org
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swapon over NFS does not go through generic_swapfile_activate
code path when setting up extents. This makes holes in NFS
swapfiles possible which is not expected for swapon.

Signed-off-by: Murphy Zhou <jencce.kernel@gmail.com>
---
 fs/nfs/file.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 8eb731d..ccd9bc0 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -489,7 +489,19 @@ static int nfs_launder_page(struct page *page)
 static int nfs_swap_activate(struct swap_info_struct *sis, struct file *file,
 						sector_t *span)
 {
+	unsigned long blocks;
+	long long isize;
 	struct rpc_clnt *clnt = NFS_CLIENT(file->f_mapping->host);
+	struct inode *inode = file->f_mapping->host;
+
+	spin_lock(&inode->i_lock);
+	blocks = inode->i_blocks;
+	isize = inode->i_size;
+	spin_unlock(&inode->i_lock);
+	if (blocks*512 < isize) {
+		pr_warn("swap activate: swapfile has holes\n");
+		return -EINVAL;
+	}
 
 	*span = sis->pages;
 
-- 
1.8.3.1