Merge tag 'xfs-4.18-fixes-2' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux

Pull xfs fixes from Darrick Wong:
 "Here are some patches for 4.18 to fix regressions, accounting
  problems, overflow problems, and to strengthen metadata validation to
  prevent corruption.

  This series has been run through a full xfstests run over the weekend
  and through a quick xfstests run against this morning's master, with
  no major failures reported.

  Changes since last update:

   - more metadata validation strengthening to prevent crashes.

   - fix extent offset overflow problem when insert_range on a 512b
     block fs

   - fix some off-by-one errors in the realtime fsmap code

   - fix some math errors in the default resblks calculation when free
     space is low

   - fix a problem where stale page contents are exposed via mmap read
     after a zero_range at eof

   - fix accounting problems with per-ag reservations causing statfs
     reports to vary incorrectly"

* tag 'xfs-4.18-fixes-2' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  xfs: fix fdblocks accounting w/ RMAPBT per-AG reservation
  xfs: ensure post-EOF zeroing happens after zeroing part of a file
  xfs: fix off-by-one error in xfs_rtalloc_query_range
  xfs: fix uninitialized field in rtbitmap fsmap backend
  xfs: recheck reflink state after grabbing ILOCK_SHARED for a write
  xfs: don't allow insert-range to shift extents past the maximum offset
  xfs: don't trip over negative free space in xfs_reserve_blocks
  xfs: allow empty transactions while frozen
  xfs: xfs_iflush_abort() can be called twice on cluster writeback failure
  xfs: More robust inode extent count validation
  xfs: simplify xfs_bmap_punch_delalloc_range

1 files changed, 27 insertions, 4 deletions

diff --git a/fs/xfs/libxfs/xfs_ag_resv.c b/fs/xfs/libxfs/xfs_ag_resv.c
index 84db76e0e3e3..fecd187fcf2c 100644
--- a/fs/xfs/libxfs/xfs_ag_resv.c
+++ b/fs/xfs/libxfs/xfs_ag_resv.c
@@ -157,6 +157,7 @@ __xfs_ag_resv_free(
 	error = xfs_mod_fdblocks(pag->pag_mount, oldresv, true);
 	resv->ar_reserved = 0;
 	resv->ar_asked = 0;
+	resv->ar_orig_reserved = 0;
 
 	if (error)
 		trace_xfs_ag_resv_free_error(pag->pag_mount, pag->pag_agno,
@@ -189,13 +190,34 @@ __xfs_ag_resv_init(
 	struct xfs_mount		*mp = pag->pag_mount;
 	struct xfs_ag_resv		*resv;
 	int				error;
-	xfs_extlen_t			reserved;
+	xfs_extlen_t			hidden_space;
 
 	if (used > ask)
 		ask = used;
-	reserved = ask - used;
 
-	error = xfs_mod_fdblocks(mp, -(int64_t)reserved, true);
+	switch (type) {
+	case XFS_AG_RESV_RMAPBT:
+		/*
+		 * Space taken by the rmapbt is not subtracted from fdblocks
+		 * because the rmapbt lives in the free space.  Here we must
+		 * subtract the entire reservation from fdblocks so that we
+		 * always have blocks available for rmapbt expansion.
+		 */
+		hidden_space = ask;
+		break;
+	case XFS_AG_RESV_METADATA:
+		/*
+		 * Space taken by all other metadata btrees are accounted
+		 * on-disk as used space.  We therefore only hide the space
+		 * that is reserved but not used by the trees.
+		 */
+		hidden_space = ask - used;
+		break;
+	default:
+		ASSERT(0);
+		return -EINVAL;
+	}
+	error = xfs_mod_fdblocks(mp, -(int64_t)hidden_space, true);
 	if (error) {
 		trace_xfs_ag_resv_init_error(pag->pag_mount, pag->pag_agno,
 				error, _RET_IP_);
@@ -216,7 +238,8 @@ __xfs_ag_resv_init(
 
 	resv = xfs_perag_resv(pag, type);
 	resv->ar_asked = ask;
-	resv->ar_reserved = resv->ar_orig_reserved = reserved;
+	resv->ar_orig_reserved = hidden_space;
+	resv->ar_reserved = ask - used;
 
 	trace_xfs_ag_resv_init(pag, type, ask);
 	return 0;