Commit 18dd78c4 authored Jun 20, 2014 by Scott Mayhew Committed by Trond Myklebust Jun 24, 2014

nfs: Fix cache_validity check in nfs_write_pageuptodate()



NFS_INO_INVALID_DATA cannot be ignored, even if we have a delegation.

We're still having some problems with data corruption when multiple
clients are appending to a file and those clients are being granted
write delegations on open.

To reproduce:

Client A:
vi /mnt/`hostname -s`
while :; do echo "XXXXXXXXXXXXXXX" >>/mnt/file; sleep $(( $RANDOM % 5 )); done

Client B:
vi /mnt/`hostname -s`
while :; do echo "YYYYYYYYYYYYYYY" >>/mnt/file; sleep $(( $RANDOM % 5 )); done

What's happening is that in nfs_update_inode() we're recognizing that
the file size has changed and we're setting NFS_INO_INVALID_DATA
accordingly, but then we ignore the cache_validity flags in
nfs_write_pageuptodate() because we have a delegation.  As a result,
in nfs_updatepage() we're extending the write to cover the full page
even though we've not read in the data to begin with.

Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Cc: <stable@vger.kernel.org> # v3.11+
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

parent a497c3ba

fs/nfs/write.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -934,12 +934,14 @@ static bool nfs_write_pageuptodate(struct page page, struct inode inode)

		if (nfs_have_delegated_attributes(inode))
		goto out;
		if (nfsi->cache_validity & (NFS_INO_INVALID_DATA\|NFS_INO_REVAL_PAGECACHE))
		if (nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE)
		return false;
		smp_rmb();
		if (test_bit(NFS_INO_INVALIDATING, &nfsi->flags))
		return false;
		out:
		if (nfsi->cache_validity & NFS_INO_INVALID_DATA)
		return false;
		return PageUptodate(page) != 0;
		}

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