From bb9b8e86ad083ecb2567ae909c1d6cb0bbaa60fe Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Mon, 3 Jun 2013 15:28:46 +1000 Subject: xfs: rework dquot CRCs Calculating dquot CRCs when the backing buffer is written back just doesn't work reliably. There are several places which manipulate dquots directly in the buffers, and they don't calculate CRCs appropriately, nor do they always set the buffer up to calculate CRCs appropriately. Firstly, if we log a dquot buffer (e.g. during allocation) it gets logged without valid CRC, and so on recovery we end up with a dquot that is not valid. Secondly, if we recover/repair a dquot, we don't have a verifier attached to the buffer and hence CRCs are not calculated on the way down to disk. Thirdly, calculating the CRC after we've changed the contents means that if we re-read the dquot from the buffer, we cannot verify the contents of the dquot are valid, as the CRC is invalid. So, to avoid all the dquot CRC errors that are being detected by the read verifier, change to using the same model as for inodes. That is, dquot CRCs are calculated and written to the backing buffer at the time the dquot is flushed to the backing buffer. If we modify the dquot directly in the backing buffer, calculate the CRC immediately after the modification is complete. Hence the dquot in the on-disk buffer should always have a valid CRC. Signed-off-by: Dave Chinner Reviewed-by: Brian Foster Reviewed-by: Ben Myers Signed-off-by: Ben Myers (cherry picked from commit 6fcdc59de28817d1fbf1bd58cc01f4f3fac858fb) --- fs/xfs/xfs_dquot.c | 37 ++++++++++++++++--------------------- 1 file changed, 16 insertions(+), 21 deletions(-) (limited to 'fs/xfs/xfs_dquot.c') diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c index a41f8bf1da37..044e97a33c8d 100644 --- a/fs/xfs/xfs_dquot.c +++ b/fs/xfs/xfs_dquot.c @@ -249,8 +249,11 @@ xfs_qm_init_dquot_blk( d->dd_diskdq.d_version = XFS_DQUOT_VERSION; d->dd_diskdq.d_id = cpu_to_be32(curid); d->dd_diskdq.d_flags = type; - if (xfs_sb_version_hascrc(&mp->m_sb)) + if (xfs_sb_version_hascrc(&mp->m_sb)) { uuid_copy(&d->dd_uuid, &mp->m_sb.sb_uuid); + xfs_update_cksum((char *)d, sizeof(struct xfs_dqblk), + XFS_DQUOT_CRC_OFF); + } } xfs_trans_dquot_buf(tp, bp, @@ -286,23 +289,6 @@ xfs_dquot_set_prealloc_limits(struct xfs_dquot *dqp) dqp->q_low_space[XFS_QLOWSP_5_PCNT] = space * 5; } -STATIC void -xfs_dquot_buf_calc_crc( - struct xfs_mount *mp, - struct xfs_buf *bp) -{ - struct xfs_dqblk *d = (struct xfs_dqblk *)bp->b_addr; - int i; - - if (!xfs_sb_version_hascrc(&mp->m_sb)) - return; - - for (i = 0; i < mp->m_quotainfo->qi_dqperchunk; i++, d++) { - xfs_update_cksum((char *)d, sizeof(struct xfs_dqblk), - offsetof(struct xfs_dqblk, dd_crc)); - } -} - STATIC bool xfs_dquot_buf_verify_crc( struct xfs_mount *mp, @@ -328,12 +314,11 @@ xfs_dquot_buf_verify_crc( for (i = 0; i < ndquots; i++, d++) { if (!xfs_verify_cksum((char *)d, sizeof(struct xfs_dqblk), - offsetof(struct xfs_dqblk, dd_crc))) + XFS_DQUOT_CRC_OFF)) return false; if (!uuid_equal(&d->dd_uuid, &mp->m_sb.sb_uuid)) return false; } - return true; } @@ -393,6 +378,11 @@ xfs_dquot_buf_read_verify( } } +/* + * we don't calculate the CRC here as that is done when the dquot is flushed to + * the buffer after the update is done. This ensures that the dquot in the + * buffer always has an up-to-date CRC value. + */ void xfs_dquot_buf_write_verify( struct xfs_buf *bp) @@ -404,7 +394,6 @@ xfs_dquot_buf_write_verify( xfs_buf_ioerror(bp, EFSCORRUPTED); return; } - xfs_dquot_buf_calc_crc(mp, bp); } const struct xfs_buf_ops xfs_dquot_buf_ops = { @@ -1151,11 +1140,17 @@ xfs_qm_dqflush( * copy the lsn into the on-disk dquot now while we have the in memory * dquot here. This can't be done later in the write verifier as we * can't get access to the log item at that point in time. + * + * We also calculate the CRC here so that the on-disk dquot in the + * buffer always has a valid CRC. This ensures there is no possibility + * of a dquot without an up-to-date CRC getting to disk. */ if (xfs_sb_version_hascrc(&mp->m_sb)) { struct xfs_dqblk *dqb = (struct xfs_dqblk *)ddqp; dqb->dd_lsn = cpu_to_be64(dqp->q_logitem.qli_item.li_lsn); + xfs_update_cksum((char *)dqb, sizeof(struct xfs_dqblk), + XFS_DQUOT_CRC_OFF); } /* -- cgit v1.2.3