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72a69cd030
Currently we use u16 bitmap to make 4k sectorsize work for 64K page size. But this u16 bitmap is not large enough to contain larger page size like 128K, nor is space efficient for 16K page size. To handle both cases, here we pack all subpage bitmaps into a larger bitmap, now btrfs_subpage::bitmaps[] will be the ultimate bitmap for subpage usage. Each sub-bitmap will has its start bit number recorded in btrfs_subpage_info::*_start, and its bitmap length will be recorded in btrfs_subpage_info::bitmap_nr_bits. All subpage bitmap operations will be converted from using direct u16 operations to bitmap operations, with above *_start calculated. For 64K page size with 4K sectorsize, this should not cause much difference. While for 16K page size, we will only need 1 unsigned long (u32) to store all the bitmaps, which saves quite some space. Furthermore, this allows us to support larger page size like 128K and 258K. Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
153 lines
5.2 KiB
C
153 lines
5.2 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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};
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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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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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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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#endif
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