Commit 60e2d255 authored by Qu Wenruo's avatar Qu Wenruo Committed by David Sterba
Browse files

btrfs: provide btrfs_page_clamp_*() helpers 



In the coming subpage RW supports, there are a lot of page status update
calls which need to be converted to subpage compatible version, which
needs @start and @len.

Some call sites already have such @start/@len and are already in
page range, like various endio functions.

But there are also call sites which need to clamp the range for subpage
case, like btrfs_dirty_pagse() and __process_contig_pages().

Here we introduce new helpers, btrfs_page_clamp_*(), to do and only do the
clamp for subpage version.

Although in theory all existing btrfs_page_*() calls can be converted to
use btrfs_page_clamp_*() directly, but that would make us to do
unnecessary clamp operations.

Tested-by: Ritesh Harjani <riteshh@linux.ibm.com> # [ppc64]
Tested-by: Anand Jain <anand.jain@oracle.com> # [aarch64]
Reviewed-by: default avatarJosef Bacik <josef@toxicpanda.com>
Signed-off-by: default avatarQu Wenruo <wqu@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent ed8f13bf

fs/btrfs/subpage.c

+38 −0
Original line number Diff line number Diff line
@@ -354,6 +354,16 @@ void btrfs_subpage_clear_writeback(const struct btrfs_fs_info *fs_info, 
	spin_unlock_irqrestore(&subpage->lock, flags);

}



static void btrfs_subpage_clamp_range(struct page *page, u64 *start, u32 *len)

{

	u64 orig_start = *start;

	u32 orig_len = *len;



	*start = max_t(u64, page_offset(page), orig_start);

	*len = min_t(u64, page_offset(page) + PAGE_SIZE,

		     orig_start + orig_len) - *start;

}



/*

 * Unlike set/clear which is dependent on each page status, for test all bits

 * are tested in the same way.
@@ -408,6 +418,34 @@ bool btrfs_page_test_##name(const struct btrfs_fs_info *fs_info, \ 
	if (unlikely(!fs_info) || fs_info->sectorsize == PAGE_SIZE)	\

		return test_page_func(page);				\

	return btrfs_subpage_test_##name(fs_info, page, start, len);	\

}									\

void btrfs_page_clamp_set_##name(const struct btrfs_fs_info *fs_info,	\

		struct page *page, u64 start, u32 len)			\

{									\

	if (unlikely(!fs_info) || fs_info->sectorsize == PAGE_SIZE) {	\

		set_page_func(page);					\

		return;							\

	}								\

	btrfs_subpage_clamp_range(page, &start, &len);			\

	btrfs_subpage_set_##name(fs_info, page, start, len);		\

}									\

void btrfs_page_clamp_clear_##name(const struct btrfs_fs_info *fs_info, \

		struct page *page, u64 start, u32 len)			\

{									\

	if (unlikely(!fs_info) || fs_info->sectorsize == PAGE_SIZE) {	\

		clear_page_func(page);					\

		return;							\

	}								\

	btrfs_subpage_clamp_range(page, &start, &len);			\

	btrfs_subpage_clear_##name(fs_info, page, start, len);		\

}									\

bool btrfs_page_clamp_test_##name(const struct btrfs_fs_info *fs_info,	\

		struct page *page, u64 start, u32 len)			\

{									\

	if (unlikely(!fs_info) || fs_info->sectorsize == PAGE_SIZE)	\

		return test_page_func(page);				\

	btrfs_subpage_clamp_range(page, &start, &len);			\

	return btrfs_subpage_test_##name(fs_info, page, start, len);	\

}

IMPLEMENT_BTRFS_PAGE_OPS(uptodate, SetPageUptodate, ClearPageUptodate,

			 PageUptodate);

fs/btrfs/subpage.h

+10 −0
Original line number Diff line number Diff line
@@ -72,6 +72,10 @@ void btrfs_subpage_end_reader(const struct btrfs_fs_info *fs_info, 
 * btrfs_page_*() are for call sites where the page can either be subpage

 * specific or regular page. The function will handle both cases.

 * But the range still needs to be inside the page.

 *

 * btrfs_page_clamp_*() are similar to btrfs_page_*(), except the range doesn't

 * need to be inside the page. Those functions will truncate the range

 * automatically.

 */

#define DECLARE_BTRFS_SUBPAGE_OPS(name)					\

void btrfs_subpage_set_##name(const struct btrfs_fs_info *fs_info,	\
@@ -85,6 +89,12 @@ void btrfs_page_set_##name(const struct btrfs_fs_info *fs_info, \ 
void btrfs_page_clear_##name(const struct btrfs_fs_info *fs_info,	\

		struct page *page, u64 start, u32 len);			\

bool btrfs_page_test_##name(const struct btrfs_fs_info *fs_info,	\

		struct page *page, u64 start, u32 len);			\

void btrfs_page_clamp_set_##name(const struct btrfs_fs_info *fs_info,	\

		struct page *page, u64 start, u32 len);			\

void btrfs_page_clamp_clear_##name(const struct btrfs_fs_info *fs_info,	\

		struct page *page, u64 start, u32 len);			\

bool btrfs_page_clamp_test_##name(const struct btrfs_fs_info *fs_info,	\

		struct page *page, u64 start, u32 len);



DECLARE_BTRFS_SUBPAGE_OPS(uptodate);