xfs: avoid mount-time deadlock in CoW extent recovery

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commit 3ecb3ac7b9 upstream.

If a malicious user corrupts the refcount btree to cause a cycle between
different levels of the tree, the next mount attempt will deadlock in
the CoW recovery routine while grabbing buffer locks.  We can use the
ability to re-grab a buffer that was previous locked to a transaction to
avoid deadlocks, so do that here.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Darrick J. Wong 2017-05-15 19:16:15 -07:00 • committed by Greg Kroah-Hartman

parent e40c145c02

commit 7fb8ab8f0a

1 changed files with 31 additions and 12 deletions

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fs/xfs/libxfs/xfs_refcount.c

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