[merged mm-stable] shmem-open-code-the-page-cache-lookup-in-shmem_get_folio_gfp.patch removed from -mm tree

[merged mm-stable] shmem-open-code-the-page-cache-lookup-in-shmem_get_folio_gfp.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: shmem: open code the page cache lookup in shmem_get_folio_gfp
has been removed from the -mm tree.  Its filename was
     shmem-open-code-the-page-cache-lookup-in-shmem_get_folio_gfp.patch

This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Christoph Hellwig <hch@lst.de>
Subject: shmem: open code the page cache lookup in shmem_get_folio_gfp
Date: Tue, 7 Mar 2023 15:34:08 +0100

Use the very low level filemap_get_entry helper to look up the entry in
the xarray, and then:

 - don't bother locking the folio if only doing a userfault notification
 - open code locking the page and checking for truncation in a related
   code block

This will allow to eventually remove the FGP_ENTRY flag.

[hughd@google.com: adjust the new comment line]
  Link: https://lkml.kernel.org/r/af178ebb-1076-a38c-1dc1-2a37ccce4a3@google.com
Link: https://lkml.kernel.org/r/20230307143410.28031-6-hch@lst.de
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/shmem.c |   14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

--- a/mm/shmem.c~shmem-open-code-the-page-cache-lookup-in-shmem_get_folio_gfp
+++ a/mm/shmem.c
@@ -1880,12 +1880,10 @@ repeat:
 	sbinfo = SHMEM_SB(inode->i_sb);
 	charge_mm = vma ? vma->vm_mm : NULL;
 
-	folio = __filemap_get_folio(mapping, index, FGP_ENTRY | FGP_LOCK, 0);
+	folio = filemap_get_entry(mapping, index);
 	if (folio && vma && userfaultfd_minor(vma)) {
-		if (!xa_is_value(folio)) {
-			folio_unlock(folio);
+		if (!xa_is_value(folio))
 			folio_put(folio);
-		}
 		*fault_type = handle_userfault(vmf, VM_UFFD_MINOR);
 		return 0;
 	}
@@ -1901,6 +1899,14 @@ repeat:
 	}
 
 	if (folio) {
+		folio_lock(folio);
+
+		/* Has the folio been truncated or swapped out? */
+		if (unlikely(folio->mapping != mapping)) {
+			folio_unlock(folio);
+			folio_put(folio);
+			goto repeat;
+		}
 		if (sgp == SGP_WRITE)
 			folio_mark_accessed(folio);
 		if (folio_test_uptodate(folio))
_

Patches currently in -mm which might be from hch@lst.de are