From: Brian Foster Date: Fri, 9 Mar 2018 22:01:58 +0000 (-0800) Subject: xfs: shutdown if block allocation overruns tx reservation X-Git-Tag: v4.17-rc1~138^2~34 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=3e78b9a4689f722538d4d3457fc10c4bf1d9cf6a;p=linux.git xfs: shutdown if block allocation overruns tx reservation The ->t_blk_res_used field tracks how many blocks have been used in the current transaction. This should never exceed the block reservation (->t_blk_res) for a particular transaction. We currently assert this condition in the transaction block accounting code, but otherwise take no additional action should this situation occur. The overrun generally has no effect if space ends up being available and the associated transaction commits. If the transaction is duplicated, however, the current block usage is used to determine the remaining block reservation to be transferred to the new transaction. If usage exceeds reservation, this calculation underflows and creates a transaction with an invalid and excessive reservation. When the second transaction commits, the release of unused blocks corrupts the in-core free space counters. With lazy superblock accounting enabled, this inconsistency eventually trickles to the on-disk superblock and corrupts the filesystem. Replace the transaction block usage accounting assert with an explicit overrun check. If the transaction overruns the reservation, shutdown the filesystem immediately to prevent corruption. Add a new assert to xfs_trans_dup() to catch any callers that might induce this invalid state in the future. Signed-off-by: Brian Foster Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong --- diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c index ec6b01834705..2ad08ec2fc21 100644 --- a/fs/xfs/xfs_trans.c +++ b/fs/xfs/xfs_trans.c @@ -119,8 +119,11 @@ xfs_trans_dup( /* We gave our writer reference to the new transaction */ tp->t_flags |= XFS_TRANS_NO_WRITECOUNT; ntp->t_ticket = xfs_log_ticket_get(tp->t_ticket); + + ASSERT(tp->t_blk_res >= tp->t_blk_res_used); ntp->t_blk_res = tp->t_blk_res - tp->t_blk_res_used; tp->t_blk_res = tp->t_blk_res_used; + ntp->t_rtx_res = tp->t_rtx_res - tp->t_rtx_res_used; tp->t_rtx_res = tp->t_rtx_res_used; ntp->t_pflags = tp->t_pflags; @@ -344,13 +347,14 @@ xfs_trans_mod_sb( break; case XFS_TRANS_SB_FDBLOCKS: /* - * Track the number of blocks allocated in the - * transaction. Make sure it does not exceed the - * number reserved. + * Track the number of blocks allocated in the transaction. + * Make sure it does not exceed the number reserved. If so, + * shutdown as this can lead to accounting inconsistency. */ if (delta < 0) { tp->t_blk_res_used += (uint)-delta; - ASSERT(tp->t_blk_res_used <= tp->t_blk_res); + if (tp->t_blk_res_used > tp->t_blk_res) + xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE); } tp->t_fdblocks_delta += delta; if (xfs_sb_version_haslazysbcount(&mp->m_sb))