The quilt patch titled
Subject: mm: add FGP_DONTCACHE folio creation flag
has been removed from the -mm tree. Its filename was
mm-add-fgp_dontcache-folio-creation-flag.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: Jens Axboe <axboe@xxxxxxxxx>
Subject: mm: add FGP_DONTCACHE folio creation flag
Date: Fri, 20 Dec 2024 08:47:50 -0700
Callers can pass this in for uncached folio creation, in which case if a
folio is newly created it gets marked as uncached. If a folio exists for
this index and lookup succeeds, then it will not get marked as uncached.
If an !uncached lookup finds a cached folio, clear the flag. For that
case, there are competeting uncached and cached users of the folio, and it
should not get pruned.
Link: https://lkml.kernel.org/r/20241220154831.1086649-13-axboe@xxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Cc: Brian Foster <bfoster@xxxxxxxxxx>
Cc: Chris Mason <clm@xxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/pagemap.h | 2 ++
mm/filemap.c | 5 +++++
2 files changed, 7 insertions(+)
--- a/include/linux/pagemap.h~mm-add-fgp_dontcache-folio-creation-flag
+++ a/include/linux/pagemap.h
@@ -710,6 +710,7 @@ pgoff_t page_cache_prev_miss(struct addr
* * %FGP_NOFS - __GFP_FS will get cleared in gfp.
* * %FGP_NOWAIT - Don't block on the folio lock.
* * %FGP_STABLE - Wait for the folio to be stable (finished writeback)
+ * * %FGP_DONTCACHE - Uncached buffered IO
* * %FGP_WRITEBEGIN - The flags to use in a filesystem write_begin()
* implementation.
*/
@@ -723,6 +724,7 @@ typedef unsigned int __bitwise fgf_t;
#define FGP_NOWAIT ((__force fgf_t)0x00000020)
#define FGP_FOR_MMAP ((__force fgf_t)0x00000040)
#define FGP_STABLE ((__force fgf_t)0x00000080)
+#define FGP_DONTCACHE ((__force fgf_t)0x00000100)
#define FGF_GET_ORDER(fgf) (((__force unsigned)fgf) >> 26) /* top 6 bits */
#define FGP_WRITEBEGIN (FGP_LOCK | FGP_WRITE | FGP_CREAT | FGP_STABLE)
--- a/mm/filemap.c~mm-add-fgp_dontcache-folio-creation-flag
+++ a/mm/filemap.c
@@ -1973,6 +1973,8 @@ no_page:
/* Init accessed so avoid atomic mark_page_accessed later */
if (fgp_flags & FGP_ACCESSED)
__folio_set_referenced(folio);
+ if (fgp_flags & FGP_DONTCACHE)
+ __folio_set_dropbehind(folio);
err = filemap_add_folio(mapping, folio, index, gfp);
if (!err)
@@ -1995,6 +1997,9 @@ no_page:
if (!folio)
return ERR_PTR(-ENOENT);
+ /* not an uncached lookup, clear uncached if set */
+ if (folio_test_dropbehind(folio) && !(fgp_flags & FGP_DONTCACHE))
+ folio_clear_dropbehind(folio);
return folio;
}
EXPORT_SYMBOL(__filemap_get_folio);
_
Patches currently in -mm which might be from axboe@xxxxxxxxx are
