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// SPDX-License-Identifier: GPL-2.0
#include <linux/slab.h>
#include "ctree.h"
#include "subpage.h"
int btrfs_attach_subpage(const struct btrfs_fs_info *fs_info,
struct page *page, enum btrfs_subpage_type type)
{
struct btrfs_subpage *subpage = NULL;
int ret;
/*
* We have cases like a dummy extent buffer page, which is not mappped
* and doesn't need to be locked.
*/
if (page->mapping)
ASSERT(PageLocked(page));
/* Either not subpage, or the page already has private attached */
if (fs_info->sectorsize == PAGE_SIZE || PagePrivate(page))
return 0;
ret = btrfs_alloc_subpage(fs_info, &subpage, type);
if (ret < 0)
return ret;
attach_page_private(page, subpage);
return 0;
}
void btrfs_detach_subpage(const struct btrfs_fs_info *fs_info,
struct page *page)
{
struct btrfs_subpage *subpage;
/* Either not subpage, or already detached */
if (fs_info->sectorsize == PAGE_SIZE || !PagePrivate(page))
return;
subpage = (struct btrfs_subpage *)detach_page_private(page);
ASSERT(subpage);
btrfs_free_subpage(subpage);
}
int btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info,
struct btrfs_subpage **ret,
enum btrfs_subpage_type type)
{
if (fs_info->sectorsize == PAGE_SIZE)
return 0;
*ret = kzalloc(sizeof(struct btrfs_subpage), GFP_NOFS);
if (!*ret)
return -ENOMEM;
spin_lock_init(&(*ret)->lock);
if (type == BTRFS_SUBPAGE_METADATA)
atomic_set(&(*ret)->eb_refs, 0);
return 0;
}
void btrfs_free_subpage(struct btrfs_subpage *subpage)
{
kfree(subpage);
}
/*
* Increase the eb_refs of current subpage.
*
* This is important for eb allocation, to prevent race with last eb freeing
* of the same page.
* With the eb_refs increased before the eb inserted into radix tree,
* detach_extent_buffer_page() won't detach the page private while we're still
* allocating the extent buffer.
*/
void btrfs_page_inc_eb_refs(const struct btrfs_fs_info *fs_info,
struct page *page)
{
struct btrfs_subpage *subpage;
if (fs_info->sectorsize == PAGE_SIZE)
return;
ASSERT(PagePrivate(page) && page->mapping);
lockdep_assert_held(&page->mapping->private_lock);
subpage = (struct btrfs_subpage *)page->private;
atomic_inc(&subpage->eb_refs);
}
void btrfs_page_dec_eb_refs(const struct btrfs_fs_info *fs_info,
struct page *page)
{
struct btrfs_subpage *subpage;
if (fs_info->sectorsize == PAGE_SIZE)
return;
ASSERT(PagePrivate(page) && page->mapping);
lockdep_assert_held(&page->mapping->private_lock);
subpage = (struct btrfs_subpage *)page->private;
ASSERT(atomic_read(&subpage->eb_refs));
atomic_dec(&subpage->eb_refs);
}
/*
* Convert the [start, start + len) range into a u16 bitmap
*
* For example: if start == page_offset() + 16K, len = 16K, we get 0x00f0.
*/
static u16 btrfs_subpage_calc_bitmap(const struct btrfs_fs_info *fs_info,
struct page *page, u64 start, u32 len)
{
const int bit_start = offset_in_page(start) >> fs_info->sectorsize_bits;
const int nbits = len >> fs_info->sectorsize_bits;
/* Basic checks */
ASSERT(PagePrivate(page) && page->private);
ASSERT(IS_ALIGNED(start, fs_info->sectorsize) &&
IS_ALIGNED(len, fs_info->sectorsize));
/*
* The range check only works for mapped page, we can still have
* unmapped page like dummy extent buffer pages.
*/
if (page->mapping)
ASSERT(page_offset(page) <= start &&
start + len <= page_offset(page) + PAGE_SIZE);
/*
* Here nbits can be 16, thus can go beyond u16 range. We make the
* first left shift to be calculate in unsigned long (at least u32),
* then truncate the result to u16.
*/
return (u16)(((1UL << nbits) - 1) << bit_start);
}
void btrfs_subpage_set_uptodate(const struct btrfs_fs_info *fs_info,
struct page *page, u64 start, u32 len)
{
struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private;
const u16 tmp = btrfs_subpage_calc_bitmap(fs_info, page, start, len);
unsigned long flags;
spin_lock_irqsave(&subpage->lock, flags);
subpage->uptodate_bitmap |= tmp;
if (subpage->uptodate_bitmap == U16_MAX)
SetPageUptodate(page);
spin_unlock_irqrestore(&subpage->lock, flags);
}
void btrfs_subpage_clear_uptodate(const struct btrfs_fs_info *fs_info,
struct page *page, u64 start, u32 len)
{
struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private;
const u16 tmp = btrfs_subpage_calc_bitmap(fs_info, page, start, len);
unsigned long flags;
spin_lock_irqsave(&subpage->lock, flags);
subpage->uptodate_bitmap &= ~tmp;
ClearPageUptodate(page);
spin_unlock_irqrestore(&subpage->lock, flags);
}
void btrfs_subpage_set_error(const struct btrfs_fs_info *fs_info,
struct page *page, u64 start, u32 len)
{
struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private;
const u16 tmp = btrfs_subpage_calc_bitmap(fs_info, page, start, len);
unsigned long flags;
spin_lock_irqsave(&subpage->lock, flags);
subpage->error_bitmap |= tmp;
SetPageError(page);
spin_unlock_irqrestore(&subpage->lock, flags);
}
void btrfs_subpage_clear_error(const struct btrfs_fs_info *fs_info,
struct page *page, u64 start, u32 len)
{
struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private;
const u16 tmp = btrfs_subpage_calc_bitmap(fs_info, page, start, len);
unsigned long flags;
spin_lock_irqsave(&subpage->lock, flags);
subpage->error_bitmap &= ~tmp;
if (subpage->error_bitmap == 0)
ClearPageError(page);
spin_unlock_irqrestore(&subpage->lock, flags);
}
/*
* Unlike set/clear which is dependent on each page status, for test all bits
* are tested in the same way.
*/
#define IMPLEMENT_BTRFS_SUBPAGE_TEST_OP(name) \
bool btrfs_subpage_test_##name(const struct btrfs_fs_info *fs_info, \
struct page *page, u64 start, u32 len) \
{ \
struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private; \
const u16 tmp = btrfs_subpage_calc_bitmap(fs_info, page, start, len); \
unsigned long flags; \
bool ret; \
\
spin_lock_irqsave(&subpage->lock, flags); \
ret = ((subpage->name##_bitmap & tmp) == tmp); \
spin_unlock_irqrestore(&subpage->lock, flags); \
return ret; \
}
IMPLEMENT_BTRFS_SUBPAGE_TEST_OP(uptodate);
IMPLEMENT_BTRFS_SUBPAGE_TEST_OP(error);
/*
* Note that, in selftests (extent-io-tests), we can have empty fs_info passed
* in. We only test sectorsize == PAGE_SIZE cases so far, thus we can fall
* back to regular sectorsize branch.
*/
#define IMPLEMENT_BTRFS_PAGE_OPS(name, set_page_func, clear_page_func, \
test_page_func) \
void btrfs_page_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_set_##name(fs_info, page, start, len); \
} \
void btrfs_page_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_clear_##name(fs_info, page, start, len); \
} \
bool btrfs_page_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); \
return btrfs_subpage_test_##name(fs_info, page, start, len); \
}
IMPLEMENT_BTRFS_PAGE_OPS(uptodate, SetPageUptodate, ClearPageUptodate,
PageUptodate);
IMPLEMENT_BTRFS_PAGE_OPS(error, SetPageError, ClearPageError, PageError);
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