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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef BTRFS_SUBPAGE_H
#define BTRFS_SUBPAGE_H
#include <linux/spinlock.h>
#include <linux/atomic.h>
struct address_space;
struct folio;
struct btrfs_fs_info;
/*
* Extra info for subpapge bitmap.
*
* For subpage we pack all uptodate/dirty/writeback/ordered bitmaps into
* one larger bitmap.
*
* This structure records how they are organized in the bitmap:
*
* /- uptodate_offset /- dirty_offset /- ordered_offset
* | | |
* v v v
* |u|u|u|u|........|u|u|d|d|.......|d|d|o|o|.......|o|o|
* |<- bitmap_nr_bits ->|
* |<----------------- total_nr_bits ------------------>|
*/
struct btrfs_subpage_info {
/* Number of bits for each bitmap */
unsigned int bitmap_nr_bits;
/* Total number of bits for the whole bitmap */
unsigned int total_nr_bits;
/*
* *_offset indicates where the bitmap starts, the length is always
* @bitmap_size, which is calculated from PAGE_SIZE / sectorsize.
*/
unsigned int uptodate_offset;
unsigned int dirty_offset;
unsigned int writeback_offset;
unsigned int ordered_offset;
unsigned int checked_offset;
/*
* For locked bitmaps, normally it's subpage representation for folio
* Locked flag, but metadata is different:
*
* - Metadata doesn't really lock the folio
* It's just to prevent page::private get cleared before the last
* end_page_read().
*/
unsigned int locked_offset;
};
/*
* Structure to trace status of each sector inside a page, attached to
* page::private for both data and metadata inodes.
*/
struct btrfs_subpage {
/* Common members for both data and metadata pages */
spinlock_t lock;
/*
* Both data and metadata needs to track how many readers are for the
* page.
* Data relies on @readers to unlock the page when last reader finished.
* While metadata doesn't need page unlock, it needs to prevent
* page::private get cleared before the last end_page_read().
*/
atomic_t readers;
union {
/*
* Structures only used by metadata
*
* @eb_refs should only be operated under private_lock, as it
* manages whether the subpage can be detached.
*/
atomic_t eb_refs;
/* Structures only used by data */
atomic_t writers;
};
unsigned long bitmaps[];
};
enum btrfs_subpage_type {
BTRFS_SUBPAGE_METADATA,
BTRFS_SUBPAGE_DATA,
};
bool btrfs_is_subpage(const struct btrfs_fs_info *fs_info, struct address_space *mapping);
void btrfs_init_subpage_info(struct btrfs_subpage_info *subpage_info, u32 sectorsize);
int btrfs_attach_subpage(const struct btrfs_fs_info *fs_info,
struct folio *folio, enum btrfs_subpage_type type);
void btrfs_detach_subpage(const struct btrfs_fs_info *fs_info, struct folio *folio);
/* Allocate additional data where page represents more than one sector */
struct btrfs_subpage *btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info,
enum btrfs_subpage_type type);
void btrfs_free_subpage(struct btrfs_subpage *subpage);
void btrfs_folio_inc_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio);
void btrfs_folio_dec_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio);
void btrfs_subpage_start_reader(const struct btrfs_fs_info *fs_info,
struct folio *folio, u64 start, u32 len);
void btrfs_subpage_end_reader(const struct btrfs_fs_info *fs_info,
struct folio *folio, u64 start, u32 len);
int btrfs_folio_start_writer_lock(const struct btrfs_fs_info *fs_info,
struct folio *folio, u64 start, u32 len);
void btrfs_folio_end_writer_lock(const struct btrfs_fs_info *fs_info,
struct folio *folio, u64 start, u32 len);
/*
* Template for subpage related operations.
*
* btrfs_subpage_*() are for call sites where the folio has subpage attached and
* the range is ensured to be inside the folio's single page.
*
* btrfs_folio_*() are for call sites where the page can either be subpage
* specific or regular folios. The function will handle both cases.
* But the range still needs to be inside one single page.
*
* btrfs_folio_clamp_*() are similar to btrfs_folio_*(), 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, \
struct folio *folio, u64 start, u32 len); \
void btrfs_subpage_clear_##name(const struct btrfs_fs_info *fs_info, \
struct folio *folio, u64 start, u32 len); \
bool btrfs_subpage_test_##name(const struct btrfs_fs_info *fs_info, \
struct folio *folio, u64 start, u32 len); \
void btrfs_folio_set_##name(const struct btrfs_fs_info *fs_info, \
struct folio *folio, u64 start, u32 len); \
void btrfs_folio_clear_##name(const struct btrfs_fs_info *fs_info, \
struct folio *folio, u64 start, u32 len); \
bool btrfs_folio_test_##name(const struct btrfs_fs_info *fs_info, \
struct folio *folio, u64 start, u32 len); \
void btrfs_folio_clamp_set_##name(const struct btrfs_fs_info *fs_info, \
struct folio *folio, u64 start, u32 len); \
void btrfs_folio_clamp_clear_##name(const struct btrfs_fs_info *fs_info, \
struct folio *folio, u64 start, u32 len); \
bool btrfs_folio_clamp_test_##name(const struct btrfs_fs_info *fs_info, \
struct folio *folio, u64 start, u32 len);
DECLARE_BTRFS_SUBPAGE_OPS(uptodate);
DECLARE_BTRFS_SUBPAGE_OPS(dirty);
DECLARE_BTRFS_SUBPAGE_OPS(writeback);
DECLARE_BTRFS_SUBPAGE_OPS(ordered);
DECLARE_BTRFS_SUBPAGE_OPS(checked);
bool btrfs_subpage_clear_and_test_dirty(const struct btrfs_fs_info *fs_info,
struct folio *folio, u64 start, u32 len);
void btrfs_folio_assert_not_dirty(const struct btrfs_fs_info *fs_info, struct folio *folio);
void btrfs_folio_unlock_writer(struct btrfs_fs_info *fs_info,
struct folio *folio, u64 start, u32 len);
void __cold btrfs_subpage_dump_bitmap(const struct btrfs_fs_info *fs_info,
struct folio *folio, u64 start, u32 len);
#endif
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