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Commit cb12c649 authored by Trond Myklebust's avatar Trond Myklebust Committed by Greg Kroah-Hartman
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NFS: Deal correctly with attribute generation counter overflow 



[ Upstream commit 9fdbfad1777cb4638f489eeb62d85432010c0031 ]

We need to use unsigned long subtraction and then convert to signed in
order to deal correcly with C overflow rules.

Fixes: f5062003 ("NFS: Set an attribute barrier on all updates")
Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 85d7a427

fs/nfs/inode.c

+4 −4
Original line number Diff line number Diff line
@@ -1430,10 +1430,10 @@ EXPORT_SYMBOL_GPL(_nfs_display_fhandle); 
 */

static int nfs_inode_attrs_need_update(const struct inode *inode, const struct nfs_fattr *fattr)

{

	const struct nfs_inode *nfsi = NFS_I(inode);

	unsigned long attr_gencount = NFS_I(inode)->attr_gencount;



	return ((long)fattr->gencount - (long)nfsi->attr_gencount) > 0 ||

		((long)nfsi->attr_gencount - (long)nfs_read_attr_generation_counter() > 0);

	return (long)(fattr->gencount - attr_gencount) > 0 ||

	       (long)(attr_gencount - nfs_read_attr_generation_counter()) > 0;

}



/*
@@ -1849,7 +1849,7 @@ static int nfs_update_inode(struct inode *inode, struct nfs_fattr *fattr) 
			nfsi->attrtimeo_timestamp = now;

		}

		/* Set the barrier to be more recent than this fattr */

		if ((long)fattr->gencount - (long)nfsi->attr_gencount > 0)

		if ((long)(fattr->gencount - nfsi->attr_gencount) > 0)

			nfsi->attr_gencount = fattr->gencount;

	}