xfs: generalize the freespace and reserved blocks handling

xfs_{add,dec}_freecounter already handles the block and RT extent
percpu counters, but it currently hardcodes the passed in counter.

Add a freecounter abstraction that uses an enum to designate the counter
and add wrappers that hide the actual percpu_counters.  This will allow
expanding the reserved block handling to the RT extent counter in the
next step, and also prepares for adding yet another such counter that
can share the code.  Both these additions will be needed for the zoned
allocator.

Also switch the flooring of the frextents counter to 0 in statfs for the
rthinherit case to a manual min_t call to match the handling of the
fdblocks counter for normal file systems.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

1 files changed, 23 insertions, 19 deletions

diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 0055066fb1d9..b08d28a895cb 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -834,10 +834,12 @@ xfs_statfs_data(
 	struct kstatfs		*st)
 {
 	int64_t			fdblocks =
-		percpu_counter_sum(&mp->m_fdblocks);
+		xfs_sum_freecounter(mp, XC_FREE_BLOCKS);
 
 	/* make sure st->f_bfree does not underflow */
-	st->f_bfree = max(0LL, fdblocks - xfs_fdblocks_unavailable(mp));
+	st->f_bfree = max(0LL,
+		fdblocks - xfs_freecounter_unavailable(mp, XC_FREE_BLOCKS));
+
 	/*
 	 * sb_dblocks can change during growfs, but nothing cares about reporting
 	 * the old or new value during growfs.
@@ -856,7 +858,7 @@ xfs_statfs_rt(
 	struct kstatfs		*st)
 {
 	st->f_bfree = xfs_rtbxlen_to_blen(mp,
-			percpu_counter_sum_positive(&mp->m_frextents));
+			xfs_sum_freecounter(mp, XC_FREE_RTEXTENTS));
 	st->f_blocks = mp->m_sb.sb_rblocks;
 }
 
@@ -1065,7 +1067,8 @@ static int
 xfs_init_percpu_counters(
 	struct xfs_mount	*mp)
 {
-	int		error;
+	int			error;
+	int			i;
 
 	error = percpu_counter_init(&mp->m_icount, 0, GFP_KERNEL);
 	if (error)
@@ -1075,30 +1078,29 @@ xfs_init_percpu_counters(
 	if (error)
 		goto free_icount;
 
-	error = percpu_counter_init(&mp->m_fdblocks, 0, GFP_KERNEL);
-	if (error)
-		goto free_ifree;
-
 	error = percpu_counter_init(&mp->m_delalloc_blks, 0, GFP_KERNEL);
 	if (error)
-		goto free_fdblocks;
+		goto free_ifree;
 
 	error = percpu_counter_init(&mp->m_delalloc_rtextents, 0, GFP_KERNEL);
 	if (error)
 		goto free_delalloc;
 
-	error = percpu_counter_init(&mp->m_frextents, 0, GFP_KERNEL);
-	if (error)
-		goto free_delalloc_rt;
+	for (i = 0; i < XC_FREE_NR; i++) {
+		error = percpu_counter_init(&mp->m_free[i].count, 0,
+				GFP_KERNEL);
+		if (error)
+			goto free_freecounters;
+	}
 
 	return 0;
 
-free_delalloc_rt:
+free_freecounters:
+	while (--i > 0)
+		percpu_counter_destroy(&mp->m_free[i].count);
 	percpu_counter_destroy(&mp->m_delalloc_rtextents);
 free_delalloc:
 	percpu_counter_destroy(&mp->m_delalloc_blks);
-free_fdblocks:
-	percpu_counter_destroy(&mp->m_fdblocks);
 free_ifree:
 	percpu_counter_destroy(&mp->m_ifree);
 free_icount:
@@ -1112,24 +1114,26 @@ xfs_reinit_percpu_counters(
 {
 	percpu_counter_set(&mp->m_icount, mp->m_sb.sb_icount);
 	percpu_counter_set(&mp->m_ifree, mp->m_sb.sb_ifree);
-	percpu_counter_set(&mp->m_fdblocks, mp->m_sb.sb_fdblocks);
-	percpu_counter_set(&mp->m_frextents, mp->m_sb.sb_frextents);
+	xfs_set_freecounter(mp, XC_FREE_BLOCKS, mp->m_sb.sb_fdblocks);
+	xfs_set_freecounter(mp, XC_FREE_RTEXTENTS, mp->m_sb.sb_frextents);
 }
 
 static void
 xfs_destroy_percpu_counters(
 	struct xfs_mount	*mp)
 {
+	enum xfs_free_counter	i;
+
+	for (i = 0; i < XC_FREE_NR; i++)
+		percpu_counter_destroy(&mp->m_free[i].count);
 	percpu_counter_destroy(&mp->m_icount);
 	percpu_counter_destroy(&mp->m_ifree);
-	percpu_counter_destroy(&mp->m_fdblocks);
 	ASSERT(xfs_is_shutdown(mp) ||
 	       percpu_counter_sum(&mp->m_delalloc_rtextents) == 0);
 	percpu_counter_destroy(&mp->m_delalloc_rtextents);
 	ASSERT(xfs_is_shutdown(mp) ||
 	       percpu_counter_sum(&mp->m_delalloc_blks) == 0);
 	percpu_counter_destroy(&mp->m_delalloc_blks);
-	percpu_counter_destroy(&mp->m_frextents);
 }
 
 static int