1/* SPDX-License-Identifier: GPL-2.0 */
  2
  3#ifndef BTRFS_SUBPAGE_H
  4#define BTRFS_SUBPAGE_H
  5
  6#include <linux/spinlock.h>
  7#include <linux/atomic.h>
  8#include <linux/sizes.h>
  9
 10struct address_space;
 11struct folio;
 12struct btrfs_fs_info;
 13
 14/*
 15 * Extra info for subpapge bitmap.
 16 *
 17 * For subpage we pack all uptodate/dirty/writeback/ordered bitmaps into
 18 * one larger bitmap.
 19 *
 20 * This structure records how they are organized in the bitmap:
 21 *
 22 * /- uptodate          /- dirty        /- ordered
 23 * |			|		|
 24 * v			v		v
 25 * |u|u|u|u|........|u|u|d|d|.......|d|d|o|o|.......|o|o|
 26 * |< sectors_per_page >|
 27 *
 28 * Unlike regular macro-like enums, here we do not go upper-case names, as
 29 * these names will be utilized in various macros to define function names.
 30 */
 31enum {
 32	btrfs_bitmap_nr_uptodate = 0,
 33	btrfs_bitmap_nr_dirty,
 34	btrfs_bitmap_nr_writeback,
 35	btrfs_bitmap_nr_ordered,
 36	btrfs_bitmap_nr_checked,
 37	btrfs_bitmap_nr_locked,
 38	btrfs_bitmap_nr_max
 39};
 40
 41/*
 42 * Structure to trace status of each sector inside a page, attached to
 43 * page::private for both data and metadata inodes.
 44 */
 45struct btrfs_subpage {
 46	/* Common members for both data and metadata pages */
 47	spinlock_t lock;
 48	union {
 49		/*
 50		 * Structures only used by metadata
 51		 *
 52		 * @eb_refs should only be operated under private_lock, as it
 53		 * manages whether the subpage can be detached.
 54		 */
 55		atomic_t eb_refs;
 56
 57		/*
 58		 * Structures only used by data,
 59		 *
 60		 * How many sectors inside the page is locked.
 61		 */
 62		atomic_t nr_locked;
 63	};
 64	unsigned long bitmaps[];
 65};
 66
 67enum btrfs_subpage_type {
 68	BTRFS_SUBPAGE_METADATA,
 69	BTRFS_SUBPAGE_DATA,
 70};
 71
 72#if PAGE_SIZE > SZ_4K
 73bool btrfs_is_subpage(const struct btrfs_fs_info *fs_info, struct address_space *mapping);
 74#else
 75static inline bool btrfs_is_subpage(const struct btrfs_fs_info *fs_info,
 76				    struct address_space *mapping)
 77{
 78	return false;
 79}
 80#endif
 81
 82int btrfs_attach_subpage(const struct btrfs_fs_info *fs_info,
 83			 struct folio *folio, enum btrfs_subpage_type type);
 84void btrfs_detach_subpage(const struct btrfs_fs_info *fs_info, struct folio *folio);
 85
 86/* Allocate additional data where page represents more than one sector */
 87struct btrfs_subpage *btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info,
 88					  enum btrfs_subpage_type type);
 89void btrfs_free_subpage(struct btrfs_subpage *subpage);
 90
 91void btrfs_folio_inc_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio);
 92void btrfs_folio_dec_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio);
 93
 94void btrfs_folio_end_lock(const struct btrfs_fs_info *fs_info,
 95			  struct folio *folio, u64 start, u32 len);
 96void btrfs_folio_set_lock(const struct btrfs_fs_info *fs_info,
 97			  struct folio *folio, u64 start, u32 len);
 98void btrfs_folio_end_lock_bitmap(const struct btrfs_fs_info *fs_info,
 99				 struct folio *folio, unsigned long bitmap);
100/*
101 * Template for subpage related operations.
102 *
103 * btrfs_subpage_*() are for call sites where the folio has subpage attached and
104 * the range is ensured to be inside the folio's single page.
105 *
106 * btrfs_folio_*() are for call sites where the page can either be subpage
107 * specific or regular folios. The function will handle both cases.
108 * But the range still needs to be inside one single page.
109 *
110 * btrfs_folio_clamp_*() are similar to btrfs_folio_*(), except the range doesn't
111 * need to be inside the page. Those functions will truncate the range
112 * automatically.
113 */
114#define DECLARE_BTRFS_SUBPAGE_OPS(name)					\
115void btrfs_subpage_set_##name(const struct btrfs_fs_info *fs_info,	\
116		struct folio *folio, u64 start, u32 len);			\
117void btrfs_subpage_clear_##name(const struct btrfs_fs_info *fs_info,	\
118		struct folio *folio, u64 start, u32 len);			\
119bool btrfs_subpage_test_##name(const struct btrfs_fs_info *fs_info,	\
120		struct folio *folio, u64 start, u32 len);			\
121void btrfs_folio_set_##name(const struct btrfs_fs_info *fs_info,	\
122		struct folio *folio, u64 start, u32 len);			\
123void btrfs_folio_clear_##name(const struct btrfs_fs_info *fs_info,	\
124		struct folio *folio, u64 start, u32 len);			\
125bool btrfs_folio_test_##name(const struct btrfs_fs_info *fs_info,	\
126		struct folio *folio, u64 start, u32 len);			\
127void btrfs_folio_clamp_set_##name(const struct btrfs_fs_info *fs_info,	\
128		struct folio *folio, u64 start, u32 len);			\
129void btrfs_folio_clamp_clear_##name(const struct btrfs_fs_info *fs_info,	\
130		struct folio *folio, u64 start, u32 len);			\
131bool btrfs_folio_clamp_test_##name(const struct btrfs_fs_info *fs_info,	\
132		struct folio *folio, u64 start, u32 len);
133
134DECLARE_BTRFS_SUBPAGE_OPS(uptodate);
135DECLARE_BTRFS_SUBPAGE_OPS(dirty);
136DECLARE_BTRFS_SUBPAGE_OPS(writeback);
137DECLARE_BTRFS_SUBPAGE_OPS(ordered);
138DECLARE_BTRFS_SUBPAGE_OPS(checked);
139
140/*
141 * Helper for error cleanup, where a folio will have its dirty flag cleared,
142 * with writeback started and finished.
143 */
144static inline void btrfs_folio_clamp_finish_io(struct btrfs_fs_info *fs_info,
145					       struct folio *locked_folio,
146					       u64 start, u32 len)
147{
148	btrfs_folio_clamp_clear_dirty(fs_info, locked_folio, start, len);
149	btrfs_folio_clamp_set_writeback(fs_info, locked_folio, start, len);
150	btrfs_folio_clamp_clear_writeback(fs_info, locked_folio, start, len);
151}
152
153bool btrfs_subpage_clear_and_test_dirty(const struct btrfs_fs_info *fs_info,
154					struct folio *folio, u64 start, u32 len);
155
156void btrfs_folio_assert_not_dirty(const struct btrfs_fs_info *fs_info,
157				  struct folio *folio, u64 start, u32 len);
158void btrfs_get_subpage_dirty_bitmap(struct btrfs_fs_info *fs_info,
159				    struct folio *folio,
160				    unsigned long *ret_bitmap);
161void __cold btrfs_subpage_dump_bitmap(const struct btrfs_fs_info *fs_info,
162				      struct folio *folio, u64 start, u32 len);
163
164#endif