xfs: replace xfs_mod_incore_sb_batched

Introduce helper functions for modifying fields in the superblock
into xfs_trans.c, the only caller of xfs_mod_incore_sb_batch().  We
can then use these directly in xfs_trans_unreserve_and_mod_sb() and
so remove another user of the xfs_mode_incore_sb() API without
losing any functionality or scalability of the transaction commit
code..

Based on a patch from Christoph Hellwig.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

1 files changed, 126 insertions, 72 deletions

diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index 4e4bc5aed6b6..220ef2c906b2 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -485,6 +485,54 @@ xfs_trans_apply_sb_deltas(
 				  sizeof(sbp->sb_frextents) - 1);
 }
 
+STATIC int
+xfs_sb_mod8(
+	uint8_t			*field,
+	int8_t			delta)
+{
+	int8_t			counter = *field;
+
+	counter += delta;
+	if (counter < 0) {
+		ASSERT(0);
+		return -EINVAL;
+	}
+	*field = counter;
+	return 0;
+}
+
+STATIC int
+xfs_sb_mod32(
+	uint32_t		*field,
+	int32_t			delta)
+{
+	int32_t			counter = *field;
+
+	counter += delta;
+	if (counter < 0) {
+		ASSERT(0);
+		return -EINVAL;
+	}
+	*field = counter;
+	return 0;
+}
+
+STATIC int
+xfs_sb_mod64(
+	uint64_t		*field,
+	int64_t			delta)
+{
+	int64_t			counter = *field;
+
+	counter += delta;
+	if (counter < 0) {
+		ASSERT(0);
+		return -EINVAL;
+	}
+	*field = counter;
+	return 0;
+}
+
 /*
  * xfs_trans_unreserve_and_mod_sb() is called to release unused reservations
  * and apply superblock counter changes to the in-core superblock.  The
@@ -492,13 +540,6 @@ xfs_trans_apply_sb_deltas(
  * applied to the in-core superblock.  The idea is that that has already been
  * done.
  *
- * This is done efficiently with a single call to xfs_mod_incore_sb_batch().
- * However, we have to ensure that we only modify each superblock field only
- * once because the application of the delta values may not be atomic. That can
- * lead to ENOSPC races occurring if we have two separate modifcations of the
- * free space counter to put back the entire reservation and then take away
- * what we used.
- *
  * If we are not logging superblock counters, then the inode allocated/free and
  * used block counts are not updated in the on disk superblock. In this case,
  * XFS_TRANS_SB_DIRTY will not be set when the transaction is updated but we
@@ -506,20 +547,15 @@ xfs_trans_apply_sb_deltas(
  */
 void
 xfs_trans_unreserve_and_mod_sb(
-	xfs_trans_t	*tp)
+	struct xfs_trans	*tp)
 {
-	xfs_mod_sb_t	msb[9];	/* If you add cases, add entries */
-	xfs_mod_sb_t	*msbp;
-	xfs_mount_t	*mp = tp->t_mountp;
-	/* REFERENCED */
-	int		error;
-	bool		rsvd = (tp->t_flags & XFS_TRANS_RESERVE) != 0;
-	int64_t		blkdelta = 0;
-	int64_t		rtxdelta = 0;
-	int64_t		idelta = 0;
-	int64_t		ifreedelta = 0;
-
-	msbp = msb;
+	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			idelta = 0;
+	int64_t			ifreedelta = 0;
+	int			error;
 
 	/* calculate deltas */
 	if (tp->t_blk_res > 0)
@@ -560,72 +596,90 @@ xfs_trans_unreserve_and_mod_sb(
 			goto out_undo_icount;
 	}
 
+	if (rtxdelta == 0 && !(tp->t_flags & XFS_TRANS_SB_DIRTY))
+		return;
+
 	/* apply remaining deltas */
+	spin_lock(&mp->m_sb_lock);
 	if (rtxdelta) {
-		error = xfs_mod_frextents(mp, rtxdelta);
+		error = xfs_sb_mod64(&mp->m_sb.sb_frextents, rtxdelta);
 		if (error)
 			goto out_undo_ifree;
 	}
 
-	if (tp->t_flags & XFS_TRANS_SB_DIRTY) {
-		if (tp->t_dblocks_delta != 0) {
-			msbp->msb_field = XFS_SBS_DBLOCKS;
-			msbp->msb_delta = tp->t_dblocks_delta;
-			msbp++;
-		}
-		if (tp->t_agcount_delta != 0) {
-			msbp->msb_field = XFS_SBS_AGCOUNT;
-			msbp->msb_delta = tp->t_agcount_delta;
-			msbp++;
-		}
-		if (tp->t_imaxpct_delta != 0) {
-			msbp->msb_field = XFS_SBS_IMAX_PCT;
-			msbp->msb_delta = tp->t_imaxpct_delta;
-			msbp++;
-		}
-		if (tp->t_rextsize_delta != 0) {
-			msbp->msb_field = XFS_SBS_REXTSIZE;
-			msbp->msb_delta = tp->t_rextsize_delta;
-			msbp++;
-		}
-		if (tp->t_rbmblocks_delta != 0) {
-			msbp->msb_field = XFS_SBS_RBMBLOCKS;
-			msbp->msb_delta = tp->t_rbmblocks_delta;
-			msbp++;
-		}
-		if (tp->t_rblocks_delta != 0) {
-			msbp->msb_field = XFS_SBS_RBLOCKS;
-			msbp->msb_delta = tp->t_rblocks_delta;
-			msbp++;
-		}
-		if (tp->t_rextents_delta != 0) {
-			msbp->msb_field = XFS_SBS_REXTENTS;
-			msbp->msb_delta = tp->t_rextents_delta;
-			msbp++;
-		}
-		if (tp->t_rextslog_delta != 0) {
-			msbp->msb_field = XFS_SBS_REXTSLOG;
-			msbp->msb_delta = tp->t_rextslog_delta;
-			msbp++;
-		}
-	}
-
-	/*
-	 * If we need to change anything, do it.
-	 */
-	if (msbp > msb) {
-		error = xfs_mod_incore_sb_batch(tp->t_mountp, msb,
-			(uint)(msbp - msb), rsvd);
+	if (tp->t_dblocks_delta != 0) {
+		error = xfs_sb_mod64(&mp->m_sb.sb_dblocks, tp->t_dblocks_delta);
 		if (error)
 			goto out_undo_frextents;
 	}
-
+	if (tp->t_agcount_delta != 0) {
+		error = xfs_sb_mod32(&mp->m_sb.sb_agcount, tp->t_agcount_delta);
+		if (error)
+			goto out_undo_dblocks;
+	}
+	if (tp->t_imaxpct_delta != 0) {
+		error = xfs_sb_mod8(&mp->m_sb.sb_imax_pct, tp->t_imaxpct_delta);
+		if (error)
+			goto out_undo_agcount;
+	}
+	if (tp->t_rextsize_delta != 0) {
+		error = xfs_sb_mod32(&mp->m_sb.sb_rextsize,
+				     tp->t_rextsize_delta);
+		if (error)
+			goto out_undo_imaxpct;
+	}
+	if (tp->t_rbmblocks_delta != 0) {
+		error = xfs_sb_mod32(&mp->m_sb.sb_rbmblocks,
+				     tp->t_rbmblocks_delta);
+		if (error)
+			goto out_undo_rextsize;
+	}
+	if (tp->t_rblocks_delta != 0) {
+		error = xfs_sb_mod64(&mp->m_sb.sb_rblocks, tp->t_rblocks_delta);
+		if (error)
+			goto out_undo_rbmblocks;
+	}
+	if (tp->t_rextents_delta != 0) {
+		error = xfs_sb_mod64(&mp->m_sb.sb_rextents,
+				     tp->t_rextents_delta);
+		if (error)
+			goto out_undo_rblocks;
+	}
+	if (tp->t_rextslog_delta != 0) {
+		error = xfs_sb_mod8(&mp->m_sb.sb_rextslog,
+				     tp->t_rextslog_delta);
+		if (error)
+			goto out_undo_rextents;
+	}
+	spin_unlock(&mp->m_sb_lock);
 	return;
 
+out_undo_rextents:
+	if (tp->t_rextents_delta)
+		xfs_sb_mod64(&mp->m_sb.sb_rextents, -tp->t_rextents_delta);
+out_undo_rblocks:
+	if (tp->t_rblocks_delta)
+		xfs_sb_mod64(&mp->m_sb.sb_rblocks, -tp->t_rblocks_delta);
+out_undo_rbmblocks:
+	if (tp->t_rbmblocks_delta)
+		xfs_sb_mod32(&mp->m_sb.sb_rbmblocks, -tp->t_rbmblocks_delta);
+out_undo_rextsize:
+	if (tp->t_rextsize_delta)
+		xfs_sb_mod32(&mp->m_sb.sb_rextsize, -tp->t_rextsize_delta);
+out_undo_imaxpct:
+	if (tp->t_rextsize_delta)
+		xfs_sb_mod8(&mp->m_sb.sb_imax_pct, -tp->t_imaxpct_delta);
+out_undo_agcount:
+	if (tp->t_agcount_delta)
+		xfs_sb_mod32(&mp->m_sb.sb_agcount, -tp->t_agcount_delta);
+out_undo_dblocks:
+	if (tp->t_dblocks_delta)
+		xfs_sb_mod64(&mp->m_sb.sb_dblocks, -tp->t_dblocks_delta);
 out_undo_frextents:
 	if (rtxdelta)
-		xfs_mod_frextents(mp, -rtxdelta);
+		xfs_sb_mod64(&mp->m_sb.sb_frextents, -rtxdelta);
 out_undo_ifree:
+	spin_unlock(&mp->m_sb_lock);
 	if (ifreedelta)
 		xfs_mod_ifree(mp, -ifreedelta);
 out_undo_icount: