linux/fs/btrfs/subpage.c
Qu Wenruo c992fa1fd5 btrfs: subpage: fix a wrong check on subpage->writers
[BUG]
When looping btrfs/074 with 64K page size and 4K sectorsize, there is a
low chance (1/50~1/100) to crash with the following ASSERT() triggered
in btrfs_subpage_start_writer():

	ret = atomic_add_return(nbits, &subpage->writers);
	ASSERT(ret == nbits); <<< This one <<<

[CAUSE]
With more debugging output on the parameters of
btrfs_subpage_start_writer(), it shows a very concerning error:

  ret=29 nbits=13 start=393216 len=53248

For @nbits it's correct, but @ret which is the returned value from
atomic_add_return(), it's not only larger than nbits, but also larger
than max sectors per page value (for 64K page size and 4K sector size,
it's 16).

This indicates that some call sites are not properly decreasing the value.

And that's exactly the case, in btrfs_page_unlock_writer(), due to the
fact that we can have page locked either by lock_page() or
process_one_page(), we have to check if the subpage has any writer.

If no writers, it's locked by lock_page() and we only need to unlock it.

But unfortunately the check for the writers are completely opposite:

	if (atomic_read(&subpage->writers))
		/* No writers, locked by plain lock_page() */
		return unlock_page(page);

We directly unlock the page if it has writers, which is the completely
opposite what we want.

Thankfully the affected call site is only limited to
extent_write_locked_range(), so it's mostly affecting compressed write.

[FIX]
Just fix the wrong check condition to fix the bug.

Fixes: e55a0de185 ("btrfs: rework page locking in __extent_writepage()")
CC: stable@vger.kernel.org # 5.16
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
2022-03-02 16:51:39 +01:00

746 lines
23 KiB
C

// SPDX-License-Identifier: GPL-2.0
#include <linux/slab.h>
#include "ctree.h"
#include "subpage.h"
#include "btrfs_inode.h"
/*
* Subpage (sectorsize < PAGE_SIZE) support overview:
*
* Limitations:
*
* - Only support 64K page size for now
* This is to make metadata handling easier, as 64K page would ensure
* all nodesize would fit inside one page, thus we don't need to handle
* cases where a tree block crosses several pages.
*
* - Only metadata read-write for now
* The data read-write part is in development.
*
* - Metadata can't cross 64K page boundary
* btrfs-progs and kernel have done that for a while, thus only ancient
* filesystems could have such problem. For such case, do a graceful
* rejection.
*
* Special behavior:
*
* - Metadata
* Metadata read is fully supported.
* Meaning when reading one tree block will only trigger the read for the
* needed range, other unrelated range in the same page will not be touched.
*
* Metadata write support is partial.
* The writeback is still for the full page, but we will only submit
* the dirty extent buffers in the page.
*
* This means, if we have a metadata page like this:
*
* Page offset
* 0 16K 32K 48K 64K
* |/////////| |///////////|
* \- Tree block A \- Tree block B
*
* Even if we just want to writeback tree block A, we will also writeback
* tree block B if it's also dirty.
*
* This may cause extra metadata writeback which results more COW.
*
* Implementation:
*
* - Common
* Both metadata and data will use a new structure, btrfs_subpage, to
* record the status of each sector inside a page. This provides the extra
* granularity needed.
*
* - Metadata
* Since we have multiple tree blocks inside one page, we can't rely on page
* locking anymore, or we will have greatly reduced concurrency or even
* deadlocks (hold one tree lock while trying to lock another tree lock in
* the same page).
*
* Thus for metadata locking, subpage support relies on io_tree locking only.
* This means a slightly higher tree locking latency.
*/
void btrfs_init_subpage_info(struct btrfs_subpage_info *subpage_info, u32 sectorsize)
{
unsigned int cur = 0;
unsigned int nr_bits;
ASSERT(IS_ALIGNED(PAGE_SIZE, sectorsize));
nr_bits = PAGE_SIZE / sectorsize;
subpage_info->bitmap_nr_bits = nr_bits;
subpage_info->uptodate_offset = cur;
cur += nr_bits;
subpage_info->error_offset = cur;
cur += nr_bits;
subpage_info->dirty_offset = cur;
cur += nr_bits;
subpage_info->writeback_offset = cur;
cur += nr_bits;
subpage_info->ordered_offset = cur;
cur += nr_bits;
subpage_info->checked_offset = cur;
cur += nr_bits;
subpage_info->total_nr_bits = cur;
}
int btrfs_attach_subpage(const struct btrfs_fs_info *fs_info,
struct page *page, enum btrfs_subpage_type type)
{
struct btrfs_subpage *subpage;
/*
* 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;
subpage = btrfs_alloc_subpage(fs_info, type);
if (IS_ERR(subpage))
return PTR_ERR(subpage);
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);
}
struct btrfs_subpage *btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info,
enum btrfs_subpage_type type)
{
struct btrfs_subpage *ret;
unsigned int real_size;
ASSERT(fs_info->sectorsize < PAGE_SIZE);
real_size = struct_size(ret, bitmaps,
BITS_TO_LONGS(fs_info->subpage_info->total_nr_bits));
ret = kzalloc(real_size, GFP_NOFS);
if (!ret)
return ERR_PTR(-ENOMEM);
spin_lock_init(&ret->lock);
if (type == BTRFS_SUBPAGE_METADATA) {
atomic_set(&ret->eb_refs, 0);
} else {
atomic_set(&ret->readers, 0);
atomic_set(&ret->writers, 0);
}
return ret;
}
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);
}
static void btrfs_subpage_assert(const struct btrfs_fs_info *fs_info,
struct page *page, u64 start, u32 len)
{
/* 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);
}
void btrfs_subpage_start_reader(const struct btrfs_fs_info *fs_info,
struct page *page, u64 start, u32 len)
{
struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private;
const int nbits = len >> fs_info->sectorsize_bits;
btrfs_subpage_assert(fs_info, page, start, len);
atomic_add(nbits, &subpage->readers);
}
void btrfs_subpage_end_reader(const struct btrfs_fs_info *fs_info,
struct page *page, u64 start, u32 len)
{
struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private;
const int nbits = len >> fs_info->sectorsize_bits;
bool is_data;
bool last;
btrfs_subpage_assert(fs_info, page, start, len);
is_data = is_data_inode(page->mapping->host);
ASSERT(atomic_read(&subpage->readers) >= nbits);
last = atomic_sub_and_test(nbits, &subpage->readers);
/*
* For data we need to unlock the page if the last read has finished.
*
* And please don't replace @last with atomic_sub_and_test() call
* inside if () condition.
* As we want the atomic_sub_and_test() to be always executed.
*/
if (is_data && last)
unlock_page(page);
}
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);
/*
* For certain call sites like btrfs_drop_pages(), we may have pages
* beyond the target range. In that case, just set @len to 0, subpage
* helpers can handle @len == 0 without any problem.
*/
if (page_offset(page) >= orig_start + orig_len)
*len = 0;
else
*len = min_t(u64, page_offset(page) + PAGE_SIZE,
orig_start + orig_len) - *start;
}
void btrfs_subpage_start_writer(const struct btrfs_fs_info *fs_info,
struct page *page, u64 start, u32 len)
{
struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private;
const int nbits = (len >> fs_info->sectorsize_bits);
int ret;
btrfs_subpage_assert(fs_info, page, start, len);
ASSERT(atomic_read(&subpage->readers) == 0);
ret = atomic_add_return(nbits, &subpage->writers);
ASSERT(ret == nbits);
}
bool btrfs_subpage_end_and_test_writer(const struct btrfs_fs_info *fs_info,
struct page *page, u64 start, u32 len)
{
struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private;
const int nbits = (len >> fs_info->sectorsize_bits);
btrfs_subpage_assert(fs_info, page, start, len);
/*
* We have call sites passing @lock_page into
* extent_clear_unlock_delalloc() for compression path.
*
* This @locked_page is locked by plain lock_page(), thus its
* subpage::writers is 0. Handle them in a special way.
*/
if (atomic_read(&subpage->writers) == 0)
return true;
ASSERT(atomic_read(&subpage->writers) >= nbits);
return atomic_sub_and_test(nbits, &subpage->writers);
}
/*
* Lock a page for delalloc page writeback.
*
* Return -EAGAIN if the page is not properly initialized.
* Return 0 with the page locked, and writer counter updated.
*
* Even with 0 returned, the page still need extra check to make sure
* it's really the correct page, as the caller is using
* find_get_pages_contig(), which can race with page invalidating.
*/
int btrfs_page_start_writer_lock(const struct btrfs_fs_info *fs_info,
struct page *page, u64 start, u32 len)
{
if (unlikely(!fs_info) || fs_info->sectorsize == PAGE_SIZE) {
lock_page(page);
return 0;
}
lock_page(page);
if (!PagePrivate(page) || !page->private) {
unlock_page(page);
return -EAGAIN;
}
btrfs_subpage_clamp_range(page, &start, &len);
btrfs_subpage_start_writer(fs_info, page, start, len);
return 0;
}
void btrfs_page_end_writer_lock(const struct btrfs_fs_info *fs_info,
struct page *page, u64 start, u32 len)
{
if (unlikely(!fs_info) || fs_info->sectorsize == PAGE_SIZE)
return unlock_page(page);
btrfs_subpage_clamp_range(page, &start, &len);
if (btrfs_subpage_end_and_test_writer(fs_info, page, start, len))
unlock_page(page);
}
static bool bitmap_test_range_all_set(unsigned long *addr, unsigned int start,
unsigned int nbits)
{
unsigned int found_zero;
found_zero = find_next_zero_bit(addr, start + nbits, start);
if (found_zero == start + nbits)
return true;
return false;
}
static bool bitmap_test_range_all_zero(unsigned long *addr, unsigned int start,
unsigned int nbits)
{
unsigned int found_set;
found_set = find_next_bit(addr, start + nbits, start);
if (found_set == start + nbits)
return true;
return false;
}
#define subpage_calc_start_bit(fs_info, page, name, start, len) \
({ \
unsigned int start_bit; \
\
btrfs_subpage_assert(fs_info, page, start, len); \
start_bit = offset_in_page(start) >> fs_info->sectorsize_bits; \
start_bit += fs_info->subpage_info->name##_offset; \
start_bit; \
})
#define subpage_test_bitmap_all_set(fs_info, subpage, name) \
bitmap_test_range_all_set(subpage->bitmaps, \
fs_info->subpage_info->name##_offset, \
fs_info->subpage_info->bitmap_nr_bits)
#define subpage_test_bitmap_all_zero(fs_info, subpage, name) \
bitmap_test_range_all_zero(subpage->bitmaps, \
fs_info->subpage_info->name##_offset, \
fs_info->subpage_info->bitmap_nr_bits)
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;
unsigned int start_bit = subpage_calc_start_bit(fs_info, page,
uptodate, start, len);
unsigned long flags;
spin_lock_irqsave(&subpage->lock, flags);
bitmap_set(subpage->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
if (subpage_test_bitmap_all_set(fs_info, subpage, uptodate))
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;
unsigned int start_bit = subpage_calc_start_bit(fs_info, page,
uptodate, start, len);
unsigned long flags;
spin_lock_irqsave(&subpage->lock, flags);
bitmap_clear(subpage->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
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;
unsigned int start_bit = subpage_calc_start_bit(fs_info, page,
error, start, len);
unsigned long flags;
spin_lock_irqsave(&subpage->lock, flags);
bitmap_set(subpage->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
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;
unsigned int start_bit = subpage_calc_start_bit(fs_info, page,
error, start, len);
unsigned long flags;
spin_lock_irqsave(&subpage->lock, flags);
bitmap_clear(subpage->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
if (subpage_test_bitmap_all_zero(fs_info, subpage, error))
ClearPageError(page);
spin_unlock_irqrestore(&subpage->lock, flags);
}
void btrfs_subpage_set_dirty(const struct btrfs_fs_info *fs_info,
struct page *page, u64 start, u32 len)
{
struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private;
unsigned int start_bit = subpage_calc_start_bit(fs_info, page,
dirty, start, len);
unsigned long flags;
spin_lock_irqsave(&subpage->lock, flags);
bitmap_set(subpage->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
spin_unlock_irqrestore(&subpage->lock, flags);
set_page_dirty(page);
}
/*
* Extra clear_and_test function for subpage dirty bitmap.
*
* Return true if we're the last bits in the dirty_bitmap and clear the
* dirty_bitmap.
* Return false otherwise.
*
* NOTE: Callers should manually clear page dirty for true case, as we have
* extra handling for tree blocks.
*/
bool btrfs_subpage_clear_and_test_dirty(const struct btrfs_fs_info *fs_info,
struct page *page, u64 start, u32 len)
{
struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private;
unsigned int start_bit = subpage_calc_start_bit(fs_info, page,
dirty, start, len);
unsigned long flags;
bool last = false;
spin_lock_irqsave(&subpage->lock, flags);
bitmap_clear(subpage->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
if (subpage_test_bitmap_all_zero(fs_info, subpage, dirty))
last = true;
spin_unlock_irqrestore(&subpage->lock, flags);
return last;
}
void btrfs_subpage_clear_dirty(const struct btrfs_fs_info *fs_info,
struct page *page, u64 start, u32 len)
{
bool last;
last = btrfs_subpage_clear_and_test_dirty(fs_info, page, start, len);
if (last)
clear_page_dirty_for_io(page);
}
void btrfs_subpage_set_writeback(const struct btrfs_fs_info *fs_info,
struct page *page, u64 start, u32 len)
{
struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private;
unsigned int start_bit = subpage_calc_start_bit(fs_info, page,
writeback, start, len);
unsigned long flags;
spin_lock_irqsave(&subpage->lock, flags);
bitmap_set(subpage->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
set_page_writeback(page);
spin_unlock_irqrestore(&subpage->lock, flags);
}
void btrfs_subpage_clear_writeback(const struct btrfs_fs_info *fs_info,
struct page *page, u64 start, u32 len)
{
struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private;
unsigned int start_bit = subpage_calc_start_bit(fs_info, page,
writeback, start, len);
unsigned long flags;
spin_lock_irqsave(&subpage->lock, flags);
bitmap_clear(subpage->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
if (subpage_test_bitmap_all_zero(fs_info, subpage, writeback)) {
ASSERT(PageWriteback(page));
end_page_writeback(page);
}
spin_unlock_irqrestore(&subpage->lock, flags);
}
void btrfs_subpage_set_ordered(const struct btrfs_fs_info *fs_info,
struct page *page, u64 start, u32 len)
{
struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private;
unsigned int start_bit = subpage_calc_start_bit(fs_info, page,
ordered, start, len);
unsigned long flags;
spin_lock_irqsave(&subpage->lock, flags);
bitmap_set(subpage->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
SetPageOrdered(page);
spin_unlock_irqrestore(&subpage->lock, flags);
}
void btrfs_subpage_clear_ordered(const struct btrfs_fs_info *fs_info,
struct page *page, u64 start, u32 len)
{
struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private;
unsigned int start_bit = subpage_calc_start_bit(fs_info, page,
ordered, start, len);
unsigned long flags;
spin_lock_irqsave(&subpage->lock, flags);
bitmap_clear(subpage->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
if (subpage_test_bitmap_all_zero(fs_info, subpage, ordered))
ClearPageOrdered(page);
spin_unlock_irqrestore(&subpage->lock, flags);
}
void btrfs_subpage_set_checked(const struct btrfs_fs_info *fs_info,
struct page *page, u64 start, u32 len)
{
struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private;
unsigned int start_bit = subpage_calc_start_bit(fs_info, page,
checked, start, len);
unsigned long flags;
spin_lock_irqsave(&subpage->lock, flags);
bitmap_set(subpage->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
if (subpage_test_bitmap_all_set(fs_info, subpage, checked))
SetPageChecked(page);
spin_unlock_irqrestore(&subpage->lock, flags);
}
void btrfs_subpage_clear_checked(const struct btrfs_fs_info *fs_info,
struct page *page, u64 start, u32 len)
{
struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private;
unsigned int start_bit = subpage_calc_start_bit(fs_info, page,
checked, start, len);
unsigned long flags;
spin_lock_irqsave(&subpage->lock, flags);
bitmap_clear(subpage->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
ClearPageChecked(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; \
unsigned int start_bit = subpage_calc_start_bit(fs_info, page, \
name, start, len); \
unsigned long flags; \
bool ret; \
\
spin_lock_irqsave(&subpage->lock, flags); \
ret = bitmap_test_range_all_set(subpage->bitmaps, start_bit, \
len >> fs_info->sectorsize_bits); \
spin_unlock_irqrestore(&subpage->lock, flags); \
return ret; \
}
IMPLEMENT_BTRFS_SUBPAGE_TEST_OP(uptodate);
IMPLEMENT_BTRFS_SUBPAGE_TEST_OP(error);
IMPLEMENT_BTRFS_SUBPAGE_TEST_OP(dirty);
IMPLEMENT_BTRFS_SUBPAGE_TEST_OP(writeback);
IMPLEMENT_BTRFS_SUBPAGE_TEST_OP(ordered);
IMPLEMENT_BTRFS_SUBPAGE_TEST_OP(checked);
/*
* 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); \
} \
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);
IMPLEMENT_BTRFS_PAGE_OPS(error, SetPageError, ClearPageError, PageError);
IMPLEMENT_BTRFS_PAGE_OPS(dirty, set_page_dirty, clear_page_dirty_for_io,
PageDirty);
IMPLEMENT_BTRFS_PAGE_OPS(writeback, set_page_writeback, end_page_writeback,
PageWriteback);
IMPLEMENT_BTRFS_PAGE_OPS(ordered, SetPageOrdered, ClearPageOrdered,
PageOrdered);
IMPLEMENT_BTRFS_PAGE_OPS(checked, SetPageChecked, ClearPageChecked, PageChecked);
/*
* Make sure not only the page dirty bit is cleared, but also subpage dirty bit
* is cleared.
*/
void btrfs_page_assert_not_dirty(const struct btrfs_fs_info *fs_info,
struct page *page)
{
struct btrfs_subpage *subpage = (struct btrfs_subpage *)page->private;
if (!IS_ENABLED(CONFIG_BTRFS_ASSERT))
return;
ASSERT(!PageDirty(page));
if (fs_info->sectorsize == PAGE_SIZE)
return;
ASSERT(PagePrivate(page) && page->private);
ASSERT(subpage_test_bitmap_all_zero(fs_info, subpage, dirty));
}
/*
* Handle different locked pages with different page sizes:
*
* - Page locked by plain lock_page()
* It should not have any subpage::writers count.
* Can be unlocked by unlock_page().
* This is the most common locked page for __extent_writepage() called
* inside extent_write_cache_pages() or extent_write_full_page().
* Rarer cases include the @locked_page from extent_write_locked_range().
*
* - Page locked by lock_delalloc_pages()
* There is only one caller, all pages except @locked_page for
* extent_write_locked_range().
* In this case, we have to call subpage helper to handle the case.
*/
void btrfs_page_unlock_writer(struct btrfs_fs_info *fs_info, struct page *page,
u64 start, u32 len)
{
struct btrfs_subpage *subpage;
ASSERT(PageLocked(page));
/* For regular page size case, we just unlock the page */
if (fs_info->sectorsize == PAGE_SIZE)
return unlock_page(page);
ASSERT(PagePrivate(page) && page->private);
subpage = (struct btrfs_subpage *)page->private;
/*
* For subpage case, there are two types of locked page. With or
* without writers number.
*
* Since we own the page lock, no one else could touch subpage::writers
* and we are safe to do several atomic operations without spinlock.
*/
if (atomic_read(&subpage->writers) == 0)
/* No writers, locked by plain lock_page() */
return unlock_page(page);
/* Have writers, use proper subpage helper to end it */
btrfs_page_end_writer_lock(fs_info, page, start, len);
}