The quilt patch titled
Subject: mm: add folio_zero_tail() and use it in ext4
has been removed from the -mm tree. Its filename was
mm-add-folio_zero_tail-and-use-it-in-ext4.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: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Subject: mm: add folio_zero_tail() and use it in ext4
Date: Tue, 7 Nov 2023 21:26:40 +0000
Patch series "Add folio_zero_tail() and folio_fill_tail()".
I'm trying to make it easier for filesystems with tailpacking / stuffing /
inline data to use folios. The primary function here is
folio_fill_tail(). You give it a pointer to memory where the data
currently is, and it takes care of copying it into the folio at that
offset. That works for gfs2 & iomap. Then There's Ext4. Rather than gin
up some kind of specialist "Here's a two pointers to two blocks of memory"
routine, just let it do its current thing, and let it call
folio_zero_tail(), which is also called by folio_fill_tail().
Other filesystems can be converted later; these ones seemed like good
examples as they're already partly or completely converted to folios.
This patch (of 3):
Instead of unmapping the folio after copying the data to it, then mapping
it again to zero the tail, provide folio_zero_tail() to zero the tail of
an already-mapped folio.
[akpm@xxxxxxxxxxxxxxxxxxxx: fix kerneldoc argument ordering]
Link: https://lkml.kernel.org/r/20231107212643.3490372-1-willy@xxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20231107212643.3490372-2-willy@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Reviewed-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
Cc: Darrick J. Wong <djwong@xxxxxxxxxx>
Cc: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/ext4/inline.c | 3 +--
include/linux/highmem.h | 38 ++++++++++++++++++++++++++++++++++++++
2 files changed, 39 insertions(+), 2 deletions(-)
--- a/fs/ext4/inline.c~mm-add-folio_zero_tail-and-use-it-in-ext4
+++ a/fs/ext4/inline.c
@@ -502,9 +502,8 @@ static int ext4_read_inline_folio(struct
BUG_ON(len > PAGE_SIZE);
kaddr = kmap_local_folio(folio, 0);
ret = ext4_read_inline_data(inode, kaddr, len, &iloc);
- flush_dcache_folio(folio);
+ kaddr = folio_zero_tail(folio, len, kaddr + len);
kunmap_local(kaddr);
- folio_zero_segment(folio, len, folio_size(folio));
folio_mark_uptodate(folio);
brelse(iloc.bh);
--- a/include/linux/highmem.h~mm-add-folio_zero_tail-and-use-it-in-ext4
+++ a/include/linux/highmem.h
@@ -484,6 +484,44 @@ static inline void memcpy_to_folio(struc
}
/**
+ * folio_zero_tail - Zero the tail of a folio.
+ * @folio: The folio to zero.
+ * @offset: The byte offset in the folio to start zeroing at.
+ * @kaddr: The address the folio is currently mapped to.
+ *
+ * If you have already used kmap_local_folio() to map a folio, written
+ * some data to it and now need to zero the end of the folio (and flush
+ * the dcache), you can use this function. If you do not have the
+ * folio kmapped (eg the folio has been partially populated by DMA),
+ * use folio_zero_range() or folio_zero_segment() instead.
+ *
+ * Return: An address which can be passed to kunmap_local().
+ */
+static inline __must_check void *folio_zero_tail(struct folio *folio,
+ size_t offset, void *kaddr)
+{
+ size_t len = folio_size(folio) - offset;
+
+ if (folio_test_highmem(folio)) {
+ size_t max = PAGE_SIZE - offset_in_page(offset);
+
+ while (len > max) {
+ memset(kaddr, 0, max);
+ kunmap_local(kaddr);
+ len -= max;
+ offset += max;
+ max = PAGE_SIZE;
+ kaddr = kmap_local_folio(folio, offset);
+ }
+ }
+
+ memset(kaddr, 0, len);
+ flush_dcache_folio(folio);
+
+ return kaddr;
+}
+
+/**
* memcpy_from_file_folio - Copy some bytes from a file folio.
* @to: The destination buffer.
* @folio: The folio to copy from.
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxx are
buffer-return-bool-from-grow_dev_folio.patch
buffer-calculate-block-number-inside-folio_init_buffers.patch
buffer-fix-grow_buffers-for-block-size-page_size.patch
buffer-cast-block-to-loff_t-before-shifting-it.patch
buffer-fix-various-functions-for-block-size-page_size.patch
buffer-handle-large-folios-in-__block_write_begin_int.patch
buffer-fix-more-functions-for-block-size-page_size.patch
nilfs2-add-nilfs_end_folio_io.patch
nilfs2-convert-nilfs_abort_logs-to-use-folios.patch
nilfs2-convert-nilfs_segctor_complete_write-to-use-folios.patch
nilfs2-convert-nilfs_forget_buffer-to-use-a-folio.patch
nilfs2-convert-to-nilfs_folio_buffers_clean.patch
nilfs2-convert-nilfs_writepage-to-use-a-folio.patch
nilfs2-convert-nilfs_mdt_write_page-to-use-a-folio.patch
nilfs2-convert-to-nilfs_clear_folio_dirty.patch
nilfs2-convert-to-__nilfs_clear_folio_dirty.patch
nilfs2-convert-nilfs_segctor_prepare_write-to-use-folios.patch
nilfs2-convert-nilfs_page_mkwrite-to-use-a-folio.patch
nilfs2-convert-nilfs_mdt_create_block-to-use-a-folio.patch
nilfs2-convert-nilfs_mdt_submit_block-to-use-a-folio.patch
nilfs2-convert-nilfs_gccache_submit_read_data-to-use-a-folio.patch
nilfs2-convert-nilfs_btnode_create_block-to-use-a-folio.patch
nilfs2-convert-nilfs_btnode_submit_block-to-use-a-folio.patch
nilfs2-convert-nilfs_btnode_delete-to-use-a-folio.patch
nilfs2-convert-nilfs_btnode_prepare_change_key-to-use-a-folio.patch
nilfs2-convert-nilfs_btnode_commit_change_key-to-use-a-folio.patch
nilfs2-convert-nilfs_btnode_abort_change_key-to-use-a-folio.patch
nilfs2-remove-page_address-from-nilfs_set_link.patch
nilfs2-remove-page_address-from-nilfs_add_link.patch
nilfs2-remove-page_address-from-nilfs_delete_entry.patch
nilfs2-return-the-mapped-address-from-nilfs_get_page.patch
nilfs2-pass-the-mapped-address-to-nilfs_check_page.patch
nilfs2-switch-to-kmap_local-for-directory-handling.patch
nilfs2-add-nilfs_get_folio.patch
nilfs2-convert-nilfs_readdir-to-use-a-folio.patch
nilfs2-convert-nilfs_find_entry-to-use-a-folio.patch
nilfs2-convert-nilfs_rename-to-use-folios.patch
nilfs2-convert-nilfs_add_link-to-use-a-folio.patch
nilfs2-convert-nilfs_empty_dir-to-use-a-folio.patch
nilfs2-convert-nilfs_make_empty-to-use-a-folio.patch
nilfs2-convert-nilfs_prepare_chunk-and-nilfs_commit_chunk-to-folios.patch
nilfs2-convert-nilfs_page_bug-to-nilfs_folio_bug.patch
