Merge tag 'xfs-4.19-merge-6' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux

Pull xfs updates from Darrick Wong:
 "This is the second part of the XFS changes for 4.19.

  The biggest changes are the removal of buffer heads frm XFS, a massive
  reworking of the deferred transaction operations handling code, the
  removal of the long defunct barrier/nobarrier mount options, and the
  addition of a few more online repair functions.

  Summary:

   - Use extent maps to track pagecache page status instead of
     bufferhead state.

   - Refactor pagecache read and write paths to use the new iomap
     library functions, which enable us to drop the old bufferhead code
     for pagesize == blocksize filesystems.

   - Set up parallel per-block-per-page metadata to track subpage
     information that was tracked by buffer heads, which enables us to
     drop the old bufferhead code for pagesize > blocksize filesystems.

   - Tie a deferred ops control structure to a transaction so that we
     can take advantage of an upper-level dfops without having to plumb
     pointer passing through the code.

   - Refactor the deferred ops code to track deferred ops as part of the
     transaction structure (instead of as a separate data structure) so
     that we can simplify the scoping rules around defer_ops.

   - Refactor twisty delwri buffer submission code to avoid deadlocks.

   - Shorten and fix indenting problems in the scrub code.

   - Detect obviously bad summary counts at mount and fix them.

   - Directly associate deferred ops control structure with a
     transaction so that callers no longer have to manage it themselves.

   - Remove a couple of IRIX-era inode macros.

   - Remove the long-deprecated 'barrier' and 'nobarrier' mount options.

   - Clean up the inode fork structure a bit.

   - Check for bad fs summary counter values in the superblock.

   - Reduce COW fork lookups during writeback.

   - Refactor the deferred ops control structures into the transaction
     structure, thereby eliminating the need for transaction users to
     handle the deferred ops as a separate data structure.

   - Add the ability to repair AG headers online.

   - Fix a crash due to insufficient return value checking.

   - Various fixes and cleanups"

* tag 'xfs-4.19-merge-6' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: (155 commits)
  xfs: fix a null pointer dereference in xfs_bmap_extents_to_btree
  xfs: remove b_last_holder & associated macros
  iomap: Switch to offset_in_page for clarity
  xfs: Close race between direct IO and xfs_break_layouts()
  xfs: repair the AGI
  xfs: repair the AGFL
  xfs: repair the AGF
  xfs: remove dead error handling code in xfs_dquot_disk_alloc()
  xfs: use WRITE_ONCE to update if_seq
  xfs: fix a comment in xfs_log_reserve
  xfs: only validate summary counts on primary superblock
  xfs: substitute spaces with tabs
  xfs: fold dfops into the transaction
  xfs: always defer agfl block frees
  xfs: pass transaction to xfs_defer_add()
  xfs: replace xfs_defer_ops ->dop_pending with on-stack list
  xfs: cancel dfops on xfs_defer_finish() error
  xfs: clean out superfluous dfops dop params/vars
  xfs: drop dop param from xfs_defer_op_type ->finish_item() callback
  xfs: automatic dfops inode relogging
  ...

1 files changed, 20 insertions, 0 deletions

diff --git a/fs/xfs/libxfs/xfs_iext_tree.c b/fs/xfs/libxfs/xfs_iext_tree.c
index b80c63faace2..771dd072015d 100644
--- a/fs/xfs/libxfs/xfs_iext_tree.c
+++ b/fs/xfs/libxfs/xfs_iext_tree.c
@@ -14,6 +14,7 @@
 #include "xfs_inode_fork.h"
 #include "xfs_trans_resv.h"
 #include "xfs_mount.h"
+#include "xfs_bmap.h"
 #include "xfs_trace.h"
 
 /*
@@ -612,6 +613,19 @@ xfs_iext_realloc_root(
 	cur->leaf = new;
 }
 
+/*
+ * Increment the sequence counter if we are on a COW fork.  This allows
+ * the writeback code to skip looking for a COW extent if the COW fork
+ * hasn't changed.  We use WRITE_ONCE here to ensure the update to the
+ * sequence counter is seen before the modifications to the extent
+ * tree itself take effect.
+ */
+static inline void xfs_iext_inc_seq(struct xfs_ifork *ifp, int state)
+{
+	if (state & BMAP_COWFORK)
+		WRITE_ONCE(ifp->if_seq, READ_ONCE(ifp->if_seq) + 1);
+}
+
 void
 xfs_iext_insert(
 	struct xfs_inode	*ip,
@@ -624,6 +638,8 @@ xfs_iext_insert(
 	struct xfs_iext_leaf	*new = NULL;
 	int			nr_entries, i;
 
+	xfs_iext_inc_seq(ifp, state);
+
 	if (ifp->if_height == 0)
 		xfs_iext_alloc_root(ifp, cur);
 	else if (ifp->if_height == 1)
@@ -864,6 +880,8 @@ xfs_iext_remove(
 	ASSERT(ifp->if_u1.if_root != NULL);
 	ASSERT(xfs_iext_valid(ifp, cur));
 
+	xfs_iext_inc_seq(ifp, state);
+
 	nr_entries = xfs_iext_leaf_nr_entries(ifp, leaf, cur->pos) - 1;
 	for (i = cur->pos; i < nr_entries; i++)
 		leaf->recs[i] = leaf->recs[i + 1];
@@ -970,6 +988,8 @@ xfs_iext_update_extent(
 {
 	struct xfs_ifork	*ifp = xfs_iext_state_to_fork(ip, state);
 
+	xfs_iext_inc_seq(ifp, state);
+
 	if (cur->pos == 0) {
 		struct xfs_bmbt_irec	old;