xfs: growfs: don't read garbage for new secondary superblocks (1375cb65) · Commits · 戴 / test

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:

Dave Chinner <dchinner@redhat.com> Reviewed-by:

Carlos Maiolino <cmaiolino@redhat.com> Signed-off-by:

Ben Myers <bpm@sgi.com>

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);

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