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, 26 insertions, 0 deletions

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 01628f0c9a0c..7205268b30bc 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -5780,6 +5780,32 @@ del_cursor:
 	return error;
 }
 
+/* Make sure we won't be right-shifting an extent past the maximum bound. */
+int
+xfs_bmap_can_insert_extents(
+	struct xfs_inode	*ip,
+	xfs_fileoff_t		off,
+	xfs_fileoff_t		shift)
+{
+	struct xfs_bmbt_irec	got;
+	int			is_empty;
+	int			error = 0;
+
+	ASSERT(xfs_isilocked(ip, XFS_IOLOCK_EXCL));
+
+	if (XFS_FORCED_SHUTDOWN(ip->i_mount))
+		return -EIO;
+
+	xfs_ilock(ip, XFS_ILOCK_EXCL);
+	error = xfs_bmap_last_extent(NULL, ip, XFS_DATA_FORK, &got, &is_empty);
+	if (!error && !is_empty && got.br_startoff >= off &&
+	    ((got.br_startoff + shift) & BMBT_STARTOFF_MASK) < got.br_startoff)
+		error = -EINVAL;
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+
+	return error;
+}
+
 int
 xfs_bmap_insert_extents(
 	struct xfs_trans	*tp,