Merge tag 'vfs-6.16-rc2.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs fixes from Christian Brauner:

 - Fix the AT_HANDLE_CONNECTABLE option so filesystems that don't know
   how to decode a connected non-dir dentry fail the request

 - Use repr(transparent) to ensure identical layout between the C and
   Rust implementation of struct file

 - Add a missing xas_pause() into the dax code employing
   wait_entry_unlocked_exclusive()

 - Fix FOP_DONTCACHE which we disabled for v6.15.

   A folio could get redirtied and/or scheduled for writeback after the
   initial dropbehind test. Change the test accordingly to handle these
   cases so we can re-enable FOP_DONTCACHE again

* tag 'vfs-6.16-rc2.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  exportfs: require ->fh_to_parent() to encode connectable file handles
  rust: file: improve safety comments
  rust: file: mark `LocalFile` as `repr(transparent)`
  fs/dax: Fix "don't skip locked entries when scanning entries"
  iomap: don't lose folio dropbehind state for overwrites
  mm/filemap: unify dropbehind flag testing and clearing
  mm/filemap: unify read/write dropbehind naming
  Revert "Disable FOP_DONTCACHE for now due to bugs"
  mm/filemap: use filemap_end_dropbehind() for read invalidation
  mm/filemap: gate dropbehind invalidate on folio !dirty && !writeback

3 files changed, 23 insertions, 3 deletions

diff --git a/fs/dax.c b/fs/dax.c
index 5087ca3b1f7b..ea0c35794bf9 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -257,7 +257,7 @@ static void *wait_entry_unlocked_exclusive(struct xa_state *xas, void *entry)
 		wq = dax_entry_waitqueue(xas, entry, &ewait.key);
 		prepare_to_wait_exclusive(wq, &ewait.wait,
 					TASK_UNINTERRUPTIBLE);
-		xas_pause(xas);
+		xas_reset(xas);
 		xas_unlock_irq(xas);
 		schedule();
 		finish_wait(wq, &ewait.wait);
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 233abf598f65..3729391a18f3 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1691,6 +1691,8 @@ static int iomap_add_to_ioend(struct iomap_writepage_ctx *wpc,
 		ioend_flags |= IOMAP_IOEND_UNWRITTEN;
 	if (wpc->iomap.flags & IOMAP_F_SHARED)
 		ioend_flags |= IOMAP_IOEND_SHARED;
+	if (folio_test_dropbehind(folio))
+		ioend_flags |= IOMAP_IOEND_DONTCACHE;
 	if (pos == wpc->iomap.offset && (wpc->iomap.flags & IOMAP_F_BOUNDARY))
 		ioend_flags |= IOMAP_IOEND_BOUNDARY;
 
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 26a04a783489..63151feb9c3f 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -436,6 +436,25 @@ allocate_blocks:
 	return 0;
 }
 
+static bool
+xfs_ioend_needs_wq_completion(
+	struct iomap_ioend	*ioend)
+{
+	/* Changing inode size requires a transaction. */
+	if (xfs_ioend_is_append(ioend))
+		return true;
+
+	/* Extent manipulation requires a transaction. */
+	if (ioend->io_flags & (IOMAP_IOEND_UNWRITTEN | IOMAP_IOEND_SHARED))
+		return true;
+
+	/* Page cache invalidation cannot be done in irq context. */
+	if (ioend->io_flags & IOMAP_IOEND_DONTCACHE)
+		return true;
+
+	return false;
+}
+
 static int
 xfs_submit_ioend(
 	struct iomap_writepage_ctx *wpc,
@@ -460,8 +479,7 @@ xfs_submit_ioend(
 	memalloc_nofs_restore(nofs_flag);
 
 	/* send ioends that might require a transaction to the completion wq */
-	if (xfs_ioend_is_append(ioend) ||
-	    (ioend->io_flags & (IOMAP_IOEND_UNWRITTEN | IOMAP_IOEND_SHARED)))
+	if (xfs_ioend_needs_wq_completion(ioend))
 		ioend->io_bio.bi_end_io = xfs_end_bio;
 
 	if (status)