159 lines
5.5 KiB
C
159 lines
5.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef BTRFS_SUBPAGE_H
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#define BTRFS_SUBPAGE_H
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#include <linux/spinlock.h>
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/*
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* Extra info for subpapge bitmap.
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*
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* For subpage we pack all uptodate/error/dirty/writeback/ordered bitmaps into
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* one larger bitmap.
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*
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* This structure records how they are organized in the bitmap:
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*
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* /- uptodate_offset /- error_offset /- dirty_offset
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* | | |
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* v v v
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* |u|u|u|u|........|u|u|e|e|.......|e|e| ... |o|o|
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* |<- bitmap_nr_bits ->|
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* |<--------------- total_nr_bits ---------------->|
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*/
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struct btrfs_subpage_info {
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/* Number of bits for each bitmap */
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unsigned int bitmap_nr_bits;
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/* Total number of bits for the whole bitmap */
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unsigned int total_nr_bits;
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/*
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* *_start indicates where the bitmap starts, the length is always
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* @bitmap_size, which is calculated from PAGE_SIZE / sectorsize.
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*/
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unsigned int uptodate_offset;
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unsigned int error_offset;
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unsigned int dirty_offset;
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unsigned int writeback_offset;
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unsigned int ordered_offset;
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unsigned int checked_offset;
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};
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/*
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* Structure to trace status of each sector inside a page, attached to
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* page::private for both data and metadata inodes.
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*/
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struct btrfs_subpage {
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/* Common members for both data and metadata pages */
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spinlock_t lock;
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/*
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* Both data and metadata needs to track how many readers are for the
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* page.
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* Data relies on @readers to unlock the page when last reader finished.
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* While metadata doesn't need page unlock, it needs to prevent
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* page::private get cleared before the last end_page_read().
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*/
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atomic_t readers;
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union {
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/*
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* Structures only used by metadata
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*
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* @eb_refs should only be operated under private_lock, as it
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* manages whether the subpage can be detached.
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*/
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atomic_t eb_refs;
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/* Structures only used by data */
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atomic_t writers;
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};
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unsigned long bitmaps[];
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};
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enum btrfs_subpage_type {
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BTRFS_SUBPAGE_METADATA,
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BTRFS_SUBPAGE_DATA,
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};
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bool btrfs_is_subpage(const struct btrfs_fs_info *fs_info, struct page *page);
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void btrfs_init_subpage_info(struct btrfs_subpage_info *subpage_info, u32 sectorsize);
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int btrfs_attach_subpage(const struct btrfs_fs_info *fs_info,
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struct page *page, enum btrfs_subpage_type type);
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void btrfs_detach_subpage(const struct btrfs_fs_info *fs_info,
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struct page *page);
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/* Allocate additional data where page represents more than one sector */
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struct btrfs_subpage *btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info,
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enum btrfs_subpage_type type);
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void btrfs_free_subpage(struct btrfs_subpage *subpage);
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void btrfs_page_inc_eb_refs(const struct btrfs_fs_info *fs_info,
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struct page *page);
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void btrfs_page_dec_eb_refs(const struct btrfs_fs_info *fs_info,
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struct page *page);
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void btrfs_subpage_start_reader(const struct btrfs_fs_info *fs_info,
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struct page *page, u64 start, u32 len);
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void btrfs_subpage_end_reader(const struct btrfs_fs_info *fs_info,
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struct page *page, u64 start, u32 len);
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void btrfs_subpage_start_writer(const struct btrfs_fs_info *fs_info,
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struct page *page, u64 start, u32 len);
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bool btrfs_subpage_end_and_test_writer(const struct btrfs_fs_info *fs_info,
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struct page *page, u64 start, u32 len);
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int btrfs_page_start_writer_lock(const struct btrfs_fs_info *fs_info,
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struct page *page, u64 start, u32 len);
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void btrfs_page_end_writer_lock(const struct btrfs_fs_info *fs_info,
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struct page *page, u64 start, u32 len);
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/*
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* Template for subpage related operations.
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*
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* btrfs_subpage_*() are for call sites where the page has subpage attached and
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* the range is ensured to be inside the page.
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*
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* btrfs_page_*() are for call sites where the page can either be subpage
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* specific or regular page. The function will handle both cases.
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* But the range still needs to be inside the page.
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*
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* btrfs_page_clamp_*() are similar to btrfs_page_*(), except the range doesn't
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* need to be inside the page. Those functions will truncate the range
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* automatically.
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*/
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#define DECLARE_BTRFS_SUBPAGE_OPS(name) \
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void btrfs_subpage_set_##name(const struct btrfs_fs_info *fs_info, \
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struct page *page, u64 start, u32 len); \
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void btrfs_subpage_clear_##name(const struct btrfs_fs_info *fs_info, \
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struct page *page, u64 start, u32 len); \
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bool btrfs_subpage_test_##name(const struct btrfs_fs_info *fs_info, \
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struct page *page, u64 start, u32 len); \
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void btrfs_page_set_##name(const struct btrfs_fs_info *fs_info, \
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struct page *page, u64 start, u32 len); \
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void btrfs_page_clear_##name(const struct btrfs_fs_info *fs_info, \
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struct page *page, u64 start, u32 len); \
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bool btrfs_page_test_##name(const struct btrfs_fs_info *fs_info, \
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struct page *page, u64 start, u32 len); \
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void btrfs_page_clamp_set_##name(const struct btrfs_fs_info *fs_info, \
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struct page *page, u64 start, u32 len); \
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void btrfs_page_clamp_clear_##name(const struct btrfs_fs_info *fs_info, \
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struct page *page, u64 start, u32 len); \
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bool btrfs_page_clamp_test_##name(const struct btrfs_fs_info *fs_info, \
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struct page *page, u64 start, u32 len);
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DECLARE_BTRFS_SUBPAGE_OPS(uptodate);
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DECLARE_BTRFS_SUBPAGE_OPS(error);
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DECLARE_BTRFS_SUBPAGE_OPS(dirty);
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DECLARE_BTRFS_SUBPAGE_OPS(writeback);
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DECLARE_BTRFS_SUBPAGE_OPS(ordered);
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DECLARE_BTRFS_SUBPAGE_OPS(checked);
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bool btrfs_subpage_clear_and_test_dirty(const struct btrfs_fs_info *fs_info,
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struct page *page, u64 start, u32 len);
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void btrfs_page_assert_not_dirty(const struct btrfs_fs_info *fs_info,
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struct page *page);
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void btrfs_page_unlock_writer(struct btrfs_fs_info *fs_info, struct page *page,
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u64 start, u32 len);
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#endif
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