Hi,
Based on the previous thread [1], this patchset introduces attach_page_private
and detach_page_private to replace attach_page_buffers and __clear_page_buffers.
Thanks a lot for the constructive suggestions and comments from Christoph,
Matthew and Dave.
And sorry for cross post to different lists since it modifies different subsystems.
RFC V2 -> RFC V3:
1. rename clear_page_private to detach_page_private.
2. Update the comments for attach/detach_page_private from Mattew.
3. add one patch to call new function in mm/migrate.c as suggested by Mattew, but
use the conservative way to keep the orginal semantics [2].
RFC -> RFC V2:
1. rename the new functions and add comments for them.
2. change the return type of attach_page_private.
3. call attach_page_private(newpage, clear_page_private(page)) to cleanup code further.
4. avoid potential use-after-free in orangefs.
[1]. https://lore.kernel.org/linux-fsdevel/[email protected]/
[2]. https://lore.kernel.org/lkml/[email protected]/
Thanks,
Guoqing
Guoqing Jiang (10):
include/linux/pagemap.h: introduce attach/detach_page_private
md: remove __clear_page_buffers and use attach/detach_page_private
btrfs: use attach/detach_page_private
fs/buffer.c: use attach/detach_page_private
f2fs: use attach/detach_page_private
iomap: use attach/detach_page_private
ntfs: replace attach_page_buffers with attach_page_private
orangefs: use attach/detach_page_private
buffer_head.h: remove attach_page_buffers
mm/migrate.c: call detach_page_private to cleanup code
drivers/md/md-bitmap.c | 12 ++----------
fs/btrfs/disk-io.c | 4 +---
fs/btrfs/extent_io.c | 21 ++++++---------------
fs/btrfs/inode.c | 23 +++++------------------
fs/buffer.c | 16 ++++------------
fs/f2fs/f2fs.h | 11 ++---------
fs/iomap/buffered-io.c | 19 ++++---------------
fs/ntfs/aops.c | 2 +-
fs/ntfs/mft.c | 2 +-
fs/orangefs/inode.c | 32 ++++++--------------------------
include/linux/buffer_head.h | 8 --------
include/linux/pagemap.h | 37 +++++++++++++++++++++++++++++++++++++
mm/migrate.c | 5 +----
13 files changed, 70 insertions(+), 122 deletions(-)
--
2.17.1
Since the new pair function is introduced, we can call them to clean the
code in btrfs.
Cc: Chris Mason <[email protected]>
Cc: Josef Bacik <[email protected]>
Cc: David Sterba <[email protected]>
Cc: [email protected]
Signed-off-by: Guoqing Jiang <[email protected]>
---
RFC V2 -> RFC V3
1. rename clear_page_private to detach_page_private.
RFC -> RFC V2
1. change the name of new functions to attach/clear_page_private.
2. call attach_page_private(newpage, clear_page_private(page)) to
cleanup code further as suggested by Dave Chinner.
fs/btrfs/disk-io.c | 4 +---
fs/btrfs/extent_io.c | 21 ++++++---------------
fs/btrfs/inode.c | 23 +++++------------------
3 files changed, 12 insertions(+), 36 deletions(-)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index d10c7be10f3b..7278789ff8a7 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -980,9 +980,7 @@ static void btree_invalidatepage(struct page *page, unsigned int offset,
btrfs_warn(BTRFS_I(page->mapping->host)->root->fs_info,
"page private not zero on page %llu",
(unsigned long long)page_offset(page));
- ClearPagePrivate(page);
- set_page_private(page, 0);
- put_page(page);
+ detach_page_private(page);
}
}
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 39e45b8a5031..bf816387715b 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3076,22 +3076,16 @@ static int submit_extent_page(unsigned int opf,
static void attach_extent_buffer_page(struct extent_buffer *eb,
struct page *page)
{
- if (!PagePrivate(page)) {
- SetPagePrivate(page);
- get_page(page);
- set_page_private(page, (unsigned long)eb);
- } else {
+ if (!PagePrivate(page))
+ attach_page_private(page, eb);
+ else
WARN_ON(page->private != (unsigned long)eb);
- }
}
void set_page_extent_mapped(struct page *page)
{
- if (!PagePrivate(page)) {
- SetPagePrivate(page);
- get_page(page);
- set_page_private(page, EXTENT_PAGE_PRIVATE);
- }
+ if (!PagePrivate(page))
+ attach_page_private(page, (void *)EXTENT_PAGE_PRIVATE);
}
static struct extent_map *
@@ -4929,10 +4923,7 @@ static void btrfs_release_extent_buffer_pages(struct extent_buffer *eb)
* We need to make sure we haven't be attached
* to a new eb.
*/
- ClearPagePrivate(page);
- set_page_private(page, 0);
- /* One for the page private */
- put_page(page);
+ detach_page_private(page);
}
if (mapped)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 320d1062068d..a7f7ff0a8b7c 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -8303,11 +8303,8 @@ btrfs_readpages(struct file *file, struct address_space *mapping,
static int __btrfs_releasepage(struct page *page, gfp_t gfp_flags)
{
int ret = try_release_extent_mapping(page, gfp_flags);
- if (ret == 1) {
- ClearPagePrivate(page);
- set_page_private(page, 0);
- put_page(page);
- }
+ if (ret == 1)
+ detach_page_private(page);
return ret;
}
@@ -8329,14 +8326,8 @@ static int btrfs_migratepage(struct address_space *mapping,
if (ret != MIGRATEPAGE_SUCCESS)
return ret;
- if (page_has_private(page)) {
- ClearPagePrivate(page);
- get_page(newpage);
- set_page_private(newpage, page_private(page));
- set_page_private(page, 0);
- put_page(page);
- SetPagePrivate(newpage);
- }
+ if (page_has_private(page))
+ attach_page_private(newpage, detach_page_private(page));
if (PagePrivate2(page)) {
ClearPagePrivate2(page);
@@ -8458,11 +8449,7 @@ static void btrfs_invalidatepage(struct page *page, unsigned int offset,
}
ClearPageChecked(page);
- if (PagePrivate(page)) {
- ClearPagePrivate(page);
- set_page_private(page, 0);
- put_page(page);
- }
+ detach_page_private(page);
}
/*
--
2.17.1
The logic in attach_page_buffers and __clear_page_buffers are quite
paired, but
1. they are located in different files.
2. attach_page_buffers is implemented in buffer_head.h, so it could be
used by other files. But __clear_page_buffers is static function in
buffer.c and other potential users can't call the function, md-bitmap
even copied the function.
So, introduce the new attach/detach_page_private to replace them. With
the new pair of function, we will remove the usage of attach_page_buffers
and __clear_page_buffers in next patches. Thanks for suggestions about
the function name from Alexander Viro, Andreas Grünbacher, Christoph
Hellwig and Matthew Wilcox.
Suggested-by: Matthew Wilcox <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: [email protected]
Cc: "Darrick J. Wong" <[email protected]>
Cc: William Kucharski <[email protected]>
Cc: "Kirill A. Shutemov" <[email protected]>
Cc: Andreas Gruenbacher <[email protected]>
Cc: Yang Shi <[email protected]>
Cc: Yafang Shao <[email protected]>
Cc: Song Liu <[email protected]>
Cc: [email protected]
Cc: Chris Mason <[email protected]>
Cc: Josef Bacik <[email protected]>
Cc: David Sterba <[email protected]>
Cc: [email protected]
Cc: Alexander Viro <[email protected]>
Cc: Jaegeuk Kim <[email protected]>
Cc: Chao Yu <[email protected]>
Cc: [email protected]
Cc: Christoph Hellwig <[email protected]>
Cc: [email protected]
Cc: Anton Altaparmakov <[email protected]>
Cc: [email protected]
Cc: Mike Marshall <[email protected]>
Cc: Martin Brandenburg <[email protected]>
Cc: [email protected]
Cc: Thomas Gleixner <[email protected]>
Cc: Sebastian Andrzej Siewior <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Andreas Dilger <[email protected]>
Signed-off-by: Guoqing Jiang <[email protected]>
---
RFC V2 -> RFC V3:
1. rename clear_page_private to detach_page_private.
2. updated the comments for the two functions.
RFC -> RFC V2: Address the comments from Christoph Hellwig
1. change function names to attach/clear_page_private and add comments.
2. change the return type of attach_page_private.
include/linux/pagemap.h | 37 +++++++++++++++++++++++++++++++++++++
1 file changed, 37 insertions(+)
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index a8f7bd8ea1c6..99dd93188a5e 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -205,6 +205,43 @@ static inline int page_cache_add_speculative(struct page *page, int count)
return __page_cache_add_speculative(page, count);
}
+/**
+ * attach_page_private - Attach private data to a page.
+ * @page: Page to attach data to.
+ * @data: Data to attach to page.
+ *
+ * Attaching private data to a page increments the page's reference count.
+ * The data must be detached before the page will be freed.
+ */
+static inline void attach_page_private(struct page *page, void *data)
+{
+ get_page(page);
+ set_page_private(page, (unsigned long)data);
+ SetPagePrivate(page);
+}
+
+/**
+ * detach_page_private - Detach private data from a page.
+ * @page: Page to detach data from.
+ *
+ * Removes the data that was previously attached to the page and decrements
+ * the refcount on the page.
+ *
+ * Return: Data that was attached to the page.
+ */
+static inline void *detach_page_private(struct page *page)
+{
+ void *data = (void *)page_private(page);
+
+ if (!PagePrivate(page))
+ return NULL;
+ ClearPagePrivate(page);
+ set_page_private(page, 0);
+ put_page(page);
+
+ return data;
+}
+
#ifdef CONFIG_NUMA
extern struct page *__page_cache_alloc(gfp_t gfp);
#else
--
2.17.1
All the callers have replaced attach_page_buffers with the new function
attach_page_private, so remove it.
Cc: Thomas Gleixner <[email protected]>
Cc: Sebastian Andrzej Siewior <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Andreas Dilger <[email protected]>
Signed-off-by: Guoqing Jiang <[email protected]>
---
No change since RFC.
include/linux/buffer_head.h | 8 --------
1 file changed, 8 deletions(-)
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index 15b765a181b8..22fb11e2d2e0 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -272,14 +272,6 @@ void buffer_init(void);
* inline definitions
*/
-static inline void attach_page_buffers(struct page *page,
- struct buffer_head *head)
-{
- get_page(page);
- SetPagePrivate(page);
- set_page_private(page, (unsigned long)head);
-}
-
static inline void get_bh(struct buffer_head *bh)
{
atomic_inc(&bh->b_count);
--
2.17.1
We can cleanup code a little by call detach_page_private here.
Cc: Andrew Morton <[email protected]>
Cc: [email protected]
Signed-off-by: Guoqing Jiang <[email protected]>
---
Added since RFC V3.
mm/migrate.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index 7160c1556f79..f214adfb3fa4 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -797,10 +797,7 @@ static int __buffer_migrate_page(struct address_space *mapping,
if (rc != MIGRATEPAGE_SUCCESS)
goto unlock_buffers;
- ClearPagePrivate(page);
- set_page_private(newpage, page_private(page));
- set_page_private(page, 0);
- put_page(page);
+ set_page_private(newpage, detach_page_private(page));
get_page(newpage);
bh = head;
--
2.17.1
After introduce attach/detach_page_private in pagemap.h, we can remove
the duplicat code and call the new functions.
Cc: Song Liu <[email protected]>
Cc: [email protected]
Signed-off-by: Guoqing Jiang <[email protected]>
---
RFC V2 -> RFC V3
1. rename clear_page_private to detach_page_private.
RFC -> RFC V2
1. change the name of new functions to attach/clear_page_private.
drivers/md/md-bitmap.c | 12 ++----------
1 file changed, 2 insertions(+), 10 deletions(-)
diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
index b952bd45bd6a..95a5f3757fa3 100644
--- a/drivers/md/md-bitmap.c
+++ b/drivers/md/md-bitmap.c
@@ -324,14 +324,6 @@ static void end_bitmap_write(struct buffer_head *bh, int uptodate)
wake_up(&bitmap->write_wait);
}
-/* copied from buffer.c */
-static void
-__clear_page_buffers(struct page *page)
-{
- ClearPagePrivate(page);
- set_page_private(page, 0);
- put_page(page);
-}
static void free_buffers(struct page *page)
{
struct buffer_head *bh;
@@ -345,7 +337,7 @@ static void free_buffers(struct page *page)
free_buffer_head(bh);
bh = next;
}
- __clear_page_buffers(page);
+ detach_page_private(page);
put_page(page);
}
@@ -374,7 +366,7 @@ static int read_page(struct file *file, unsigned long index,
ret = -ENOMEM;
goto out;
}
- attach_page_buffers(page, bh);
+ attach_page_private(page, bh);
blk_cur = index << (PAGE_SHIFT - inode->i_blkbits);
while (bh) {
block = blk_cur;
--
2.17.1
On Thu, May 7, 2020 at 2:44 PM Guoqing Jiang
<[email protected]> wrote:
>
> After introduce attach/detach_page_private in pagemap.h, we can remove
> the duplicat code and call the new functions.
>
> Cc: Song Liu <[email protected]>
> Cc: [email protected]
> Signed-off-by: Guoqing Jiang <[email protected]>
Acked-by: Song Liu <[email protected]>