Commit 5e1e4d4f authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Chandan Babu R
Browse files

xfs: block deltas in xfs_trans_unreserve_and_mod_sb must be positive 



And to make that more clear, rearrange the code a bit and add asserts
and a comment.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatar"Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: default avatarChandan Babu R <chandanbabu@kernel.org>
parent de37dbd0

fs/xfs/xfs_trans.c

+24 −14
Original line number Diff line number Diff line
@@ -594,28 +594,38 @@ xfs_trans_unreserve_and_mod_sb( 
{

	struct xfs_mount	*mp = tp->t_mountp;

	bool			rsvd = (tp->t_flags & XFS_TRANS_RESERVE) != 0;

	int64_t			blkdelta = 0;

	int64_t			rtxdelta = 0;

	int64_t			blkdelta = tp->t_blk_res;

	int64_t			rtxdelta = tp->t_rtx_res;

	int64_t			idelta = 0;

	int64_t			ifreedelta = 0;

	int			error;



	/* calculate deltas */

	if (tp->t_blk_res > 0)

		blkdelta = tp->t_blk_res;

	if ((tp->t_fdblocks_delta != 0) &&

	    (xfs_has_lazysbcount(mp) ||

	     (tp->t_flags & XFS_TRANS_SB_DIRTY)))

	/*

	 * Calculate the deltas.

	 *

	 * t_fdblocks_delta and t_frextents_delta can be positive or negative:

	 *

	 *  - positive values indicate blocks freed in the transaction.

	 *  - negative values indicate blocks allocated in the transaction

	 *

	 * Negative values can only happen if the transaction has a block

	 * reservation that covers the allocated block.  The end result is

	 * that the calculated delta values must always be positive and we

	 * can only put back previous allocated or reserved blocks here.

	 */

	ASSERT(tp->t_blk_res || tp->t_fdblocks_delta >= 0);

	if (xfs_has_lazysbcount(mp) || (tp->t_flags & XFS_TRANS_SB_DIRTY)) {

	        blkdelta += tp->t_fdblocks_delta;

		ASSERT(blkdelta >= 0);

	}



	if (tp->t_rtx_res > 0)

		rtxdelta = tp->t_rtx_res;

	if ((tp->t_frextents_delta != 0) &&

	    (tp->t_flags & XFS_TRANS_SB_DIRTY))

	ASSERT(tp->t_rtx_res || tp->t_frextents_delta >= 0);

	if (tp->t_flags & XFS_TRANS_SB_DIRTY) {

		rtxdelta += tp->t_frextents_delta;

		ASSERT(rtxdelta >= 0);

	}



	if (xfs_has_lazysbcount(mp) ||

	     (tp->t_flags & XFS_TRANS_SB_DIRTY)) {

	if (xfs_has_lazysbcount(mp) || (tp->t_flags & XFS_TRANS_SB_DIRTY)) {

		idelta = tp->t_icount_delta;

		ifreedelta = tp->t_ifree_delta;

	}