Date:   Tue,  6 Oct 2020 21:06:02 -0400
From:   jglisse@...hat.com
To:     linux-kernel@...r.kernel.org
Cc:     Jérôme Glisse <jglisse@...hat.com>,
        linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Tejun Heo <tj@...nel.org>, Jan Kara <jack@...e.cz>,
        Josef Bacik <jbacik@...com>
Subject: [PATCH 13/14] mm: add struct address_space to isolate_page() callback

From: Jérôme Glisse <jglisse@...hat.com>

This is part of patchset to remove dependency on struct page.mapping
field so that we can temporarily update it to point to a special
structure tracking temporary page state (note that original mapping
pointer is preserved and can still be accessed but at a cost).

Add struct address_space to isolate_page() callback arguments.

Note that this patch does not make use of the new argument, nor does
it use a valid one at call site (by default this patch just use NULL
for new argument value).

Use following script (from root of linux kernel tree):

./that-script.sh that-semantic-patch.spatch

%<--------------------------------------------------------------------
#!/bin/sh
spatch_file=$1

echo PART1 ===========================================================

# P1 find callback functions name
spatch  --dir . --no-includes -D part1 --sp-file $spatch_file

echo PART2 ===========================================================

# P2 change callback function prototype
cat /tmp/unicorn-functions | sort | uniq | while read func ; do
    for file in $( git grep -l $func -- '*.[ch]' ) ; do
        echo $file
        spatch --no-includes --in-place -D part2 \
               -D fn=$func --sp-file $spatch_file $file
    done
done

echo PART 3 ==========================================================

# P3 find all function which call the callback
spatch --dir . --include-headers -D part3 --sp-file $spatch_file

echo PART 4===========================================================

# P4 change all funcitons which call the callback
cat /tmp/unicorn-files | sort | uniq | while read file ; do
    echo $file
    spatch --no-includes --in-place -D part4 \
           --sp-file $spatch_file $file
done
-------------------------------------------------------------------->%

With the following semantic patch:

%<--------------------------------------------------------------------
virtual part1, part2, part3, part4

// ----------------------------------------------------------------------------
// Part 1 is grepping all function that are use as callback for isolate_page.

// initialize file where we collect all function name (erase it)
@initialize:python depends on part1@
@@
file=open('/tmp/unicorn-functions', 'w')
file.close()

// match function name use as a callback
@p1r2 depends on part1@
identifier I1, FN;
@@
struct address_space_operations I1 = {..., .isolate_page = FN, ...};

@script:python p1r3 depends on p1r2@
funcname << p1r2.FN;
@@
if funcname != "NULL":
  file=open('/tmp/unicorn-functions', 'a')
  file.write(funcname + '\n')
  file.close()

// -------------------------------------------------------------------
// Part 2 modify callback

// Add address_space argument to the function (isolate_page callback one)
@p2r1 depends on part2@
identifier virtual.fn;
identifier I1, I2;
type R, T1, T2;
@@
R fn(
+struct address_space *__mapping,
T1 I1, T2 I2) { ... }

@p2r2 depends on part2@
identifier virtual.fn;
identifier I1, I2;
type R, T1, T2;
@@
R fn(
+struct address_space *__mapping,
T1 I1, T2 I2);

@p2r3 depends on part2@
identifier virtual.fn;
expression E1, E2;
@@
fn(
+MAPPING_NULL,
E1, E2)

// ----------------------------------------------------------------------------
// Part 3 is grepping all function that are use the callback for isolate_page.

// initialize file where we collect all function name (erase it)
@initialize:python depends on part3@
@@
file=open('/tmp/unicorn-files', 'w')
file.write("./include/linux/pagemap.h\n")
file.write("./include/linux/mm.h\n")
file.write("./include/linux/fs.h\n")
file.write("./mm/readahead.c\n")
file.write("./mm/filemap.c\n")
file.close()

@p3r1 depends on part3 exists@
expression E1, E2, E3;
identifier FN;
position P;
@@
FN@P(...) {...
(
E1.a_ops->isolate_page(E2, E3)
|
E1->a_ops->isolate_page(E2, E3)
)
...}

@script:python p3r2 depends on p3r1@
P << p3r1.P;
@@
file=open('/tmp/unicorn-files', 'a')
file.write(P[0].file + '\n')
file.close()

// -------------------------------------------------------------------
// Part 4 generic modification
@p4r1 depends on part4@
type R;
@@
struct address_space_operations { ... R (*isolate_page)(
+struct address_space *,
struct page *, ...); ... };

@p4r2 depends on part4@
expression E1, E2, E3;
@@
E1.a_ops->isolate_page(
+MAPPING_NULL,
E2, E3)

@p4r3 depends on part4@
expression E1, E2, E3;
@@
E1->a_ops->isolate_page(
+MAPPING_NULL,
E2, E3)
-------------------------------------------------------------------->%

Signed-off-by: Jérôme Glisse <jglisse@...hat.com>
Cc: linux-mm@...ck.org
Cc: linux-fsdevel@...r.kernel.org
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Alexander Viro <viro@...iv.linux.org.uk>
Cc: linux-fsdevel@...r.kernel.org
Cc: Tejun Heo <tj@...nel.org>
Cc: Jan Kara <jack@...e.cz>
Cc: Josef Bacik <jbacik@...com>
---
 include/linux/balloon_compaction.h | 5 +++--
 include/linux/fs.h                 | 3 ++-
 mm/balloon_compaction.c            | 3 ++-
 mm/migrate.c                       | 2 +-
 mm/z3fold.c                        | 3 ++-
 mm/zsmalloc.c                      | 3 ++-
 6 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/include/linux/balloon_compaction.h b/include/linux/balloon_compaction.h
index 07b235161d040..c1e45339a53c1 100644
--- a/include/linux/balloon_compaction.h
+++ b/include/linux/balloon_compaction.h
@@ -80,8 +80,9 @@ static inline void balloon_devinfo_init(struct balloon_dev_info *balloon)
 
 #ifdef CONFIG_BALLOON_COMPACTION
 extern const struct address_space_operations balloon_aops;
-extern bool balloon_page_isolate(struct page *page,
-				isolate_mode_t mode);
+extern bool balloon_page_isolate(struct address_space *__mapping,
+				 struct page *page,
+				 isolate_mode_t mode);
 extern void balloon_page_putback(struct address_space *__mapping,
 				 struct page *page);
 extern int balloon_page_migrate(struct address_space *mapping,
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 21f179e7c5daa..6798a13e3c980 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -408,7 +408,8 @@ struct address_space_operations {
 	 */
 	int (*migratepage) (struct address_space *,
 			struct page *, struct page *, enum migrate_mode);
-	bool (*isolate_page)(struct page *, isolate_mode_t);
+	bool (*isolate_page)(struct address_space *, struct page *,
+			     isolate_mode_t);
 	void (*putback_page)(struct address_space *, struct page *);
 	int (*launder_page) (struct address_space *, struct page *);
 	int (*is_partially_uptodate) (struct address_space *, struct page *,
diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
index abc4a63df9903..ed9120e6c9bfe 100644
--- a/mm/balloon_compaction.c
+++ b/mm/balloon_compaction.c
@@ -203,7 +203,8 @@ EXPORT_SYMBOL_GPL(balloon_page_dequeue);
 
 #ifdef CONFIG_BALLOON_COMPACTION
 
-bool balloon_page_isolate(struct page *page, isolate_mode_t mode)
+bool balloon_page_isolate(struct address_space *__mapping, struct page *page,
+			  isolate_mode_t mode)
 
 {
 	struct balloon_dev_info *b_dev_info = balloon_page_device(page);
diff --git a/mm/migrate.c b/mm/migrate.c
index 3fba7429151bf..a3220050fbe05 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -126,7 +126,7 @@ int isolate_movable_page(struct page *page, isolate_mode_t mode)
 	mapping = page_mapping(page);
 	VM_BUG_ON_PAGE(!mapping, page);
 
-	if (!mapping->a_ops->isolate_page(page, mode))
+	if (!mapping->a_ops->isolate_page(MAPPING_NULL, page, mode))
 		goto out_no_isolated;
 
 	/* Driver shouldn't use PG_isolated bit of page->flags */
diff --git a/mm/z3fold.c b/mm/z3fold.c
index 37453a14257a4..4ca02bb55a56b 100644
--- a/mm/z3fold.c
+++ b/mm/z3fold.c
@@ -1566,7 +1566,8 @@ static u64 z3fold_get_pool_size(struct z3fold_pool *pool)
 	return atomic64_read(&pool->pages_nr);
 }
 
-static bool z3fold_page_isolate(struct page *page, isolate_mode_t mode)
+static bool z3fold_page_isolate(struct address_space *__mapping,
+				struct page *page, isolate_mode_t mode)
 {
 	struct z3fold_header *zhdr;
 	struct z3fold_pool *pool;
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 99d74c6e98216..c896f069e5b0a 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -1914,7 +1914,8 @@ static void replace_sub_page(struct size_class *class, struct zspage *zspage,
 	__SetPageMovable(newpage, page_mapping(oldpage));
 }
 
-static bool zs_page_isolate(struct page *page, isolate_mode_t mode)
+static bool zs_page_isolate(struct address_space *__mapping,
+			    struct page *page, isolate_mode_t mode)
 {
 	struct zs_pool *pool;
 	struct size_class *class;
-- 
2.26.2

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