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Commit 1375cb65 authored by Dave Chinner's avatar Dave Chinner Committed by Ben Myers
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xfs: growfs: don't read garbage for new secondary superblocks 



When updating new secondary superblocks in a growfs operation, the
superblock buffer is read from the newly grown region of the
underlying device. This is not guaranteed to be zero, so violates
the underlying assumption that the unused parts of superblocks are
zero filled. Get a new buffer for these secondary superblocks to
ensure that the unused regions are zero filled correctly.

Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatarCarlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: default avatarBen Myers <bpm@sgi.com>
parent e04426b9

fs/xfs/xfs_fsops.c

+19 −2
Original line number Diff line number Diff line
@@ -399,9 +399,26 @@ xfs_growfs_data_private( 


	/* update secondary superblocks. */

	for (agno = 1; agno < nagcount; agno++) {

		error = 0;

		/*

		 * new secondary superblocks need to be zeroed, not read from

		 * disk as the contents of the new area we are growing into is

		 * completely unknown.

		 */

		if (agno < oagcount) {

			error = xfs_trans_read_buf(mp, NULL, mp->m_ddev_targp,

				  XFS_AGB_TO_DADDR(mp, agno, XFS_SB_BLOCK(mp)),

				  XFS_FSS_TO_BB(mp, 1), 0, &bp);

		} else {

			bp = xfs_trans_get_buf(NULL, mp->m_ddev_targp,

				  XFS_AGB_TO_DADDR(mp, agno, XFS_SB_BLOCK(mp)),

				  XFS_FSS_TO_BB(mp, 1), 0);

			if (bp)

				xfs_buf_zero(bp, 0, BBTOB(bp->b_length));

			else

				error = ENOMEM;

		}



		if (error) {

			xfs_warn(mp,

		"error %d reading secondary superblock for ag %d",
@@ -423,7 +440,7 @@ xfs_growfs_data_private( 
			break; /* no point in continuing */

		}

	}

	return 0;

	return error;



 error0:

	xfs_trans_cancel(tp, XFS_TRANS_ABORT);