// SPDX-License-Identifier: GPL-2.0

#include <linux/slab.h>
#include "messages.h"
#include "subpage.h"
#include "btrfs_inode.h"

/*
 * Subpage (block size < folio 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_folio_state, 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.
 */

int btrfs_attach_folio_state(const struct btrfs_fs_info *fs_info,
                             struct folio *folio, enum btrfs_folio_type type)
{
        struct btrfs_folio_state *bfs;

        /* For metadata we don't support large folio yet. */
        if (type == BTRFS_SUBPAGE_METADATA)
                ASSERT(!folio_test_large(folio));

        /*
         * We have cases like a dummy extent buffer page, which is not mapped
         * and doesn't need to be locked.
         */
        if (folio->mapping)
                ASSERT(folio_test_locked(folio));

        /* Either not subpage, or the folio already has private attached. */
        if (folio_test_private(folio))
                return 0;
        if (type == BTRFS_SUBPAGE_METADATA && !btrfs_meta_is_subpage(fs_info))
                return 0;
        if (type == BTRFS_SUBPAGE_DATA && !btrfs_is_subpage(fs_info, folio))
                return 0;

        bfs = btrfs_alloc_folio_state(fs_info, folio_size(folio), type);
        if (IS_ERR(bfs))
                return PTR_ERR(bfs);

        folio_attach_private(folio, bfs);
        return 0;
}

void btrfs_detach_folio_state(const struct btrfs_fs_info *fs_info, struct folio *folio,
                              enum btrfs_folio_type type)
{
        struct btrfs_folio_state *bfs;

        /* Either not subpage, or the folio already has private attached. */
        if (!folio_test_private(folio))
                return;
        if (type == BTRFS_SUBPAGE_METADATA && !btrfs_meta_is_subpage(fs_info))
                return;
        if (type == BTRFS_SUBPAGE_DATA && !btrfs_is_subpage(fs_info, folio))
                return;

        bfs = folio_detach_private(folio);
        ASSERT(bfs);
        btrfs_free_folio_state(bfs);
}

struct btrfs_folio_state *btrfs_alloc_folio_state(const struct btrfs_fs_info *fs_info,
                                                  size_t fsize, enum btrfs_folio_type type)
{
        struct btrfs_folio_state *ret;
        unsigned int real_size;

        ASSERT(fs_info->sectorsize < fsize);

        real_size = struct_size(ret, bitmaps,
                        BITS_TO_LONGS(btrfs_bitmap_nr_max *
                                      (fsize >> fs_info->sectorsize_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->nr_locked, 0);
        return ret;
}

/*
 * 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 folio private while we're still
 * allocating the extent buffer.
 */
void btrfs_folio_inc_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio)
{
        struct btrfs_folio_state *bfs;

        if (!btrfs_meta_is_subpage(fs_info))
                return;

        ASSERT(folio_test_private(folio) && folio->mapping);
        lockdep_assert_held(&folio->mapping->i_private_lock);

        bfs = folio_get_private(folio);
        atomic_inc(&bfs->eb_refs);
}

void btrfs_folio_dec_eb_refs(const struct btrfs_fs_info *fs_info, struct folio *folio)
{
        struct btrfs_folio_state *bfs;

        if (!btrfs_meta_is_subpage(fs_info))
                return;

        ASSERT(folio_test_private(folio) && folio->mapping);
        lockdep_assert_held(&folio->mapping->i_private_lock);

        bfs = folio_get_private(folio);
        ASSERT(atomic_read(&bfs->eb_refs));
        atomic_dec(&bfs->eb_refs);
}

static void btrfs_subpage_assert(const struct btrfs_fs_info *fs_info,
                                 struct folio *folio, u64 start, u32 len)
{
        /* Basic checks */
        ASSERT(folio_test_private(folio) && folio_get_private(folio));
        ASSERT(IS_ALIGNED(start, fs_info->sectorsize) &&
               IS_ALIGNED(len, fs_info->sectorsize), "start=%llu len=%u", start, len);
        /*
         * The range check only works for mapped page, we can still have
         * unmapped page like dummy extent buffer pages.
         */
        if (folio->mapping)
                ASSERT(folio_pos(folio) <= start &&
                       start + len <= folio_next_pos(folio),
                       "start=%llu len=%u folio_pos=%llu folio_size=%zu",
                       start, len, folio_pos(folio), folio_size(folio));
}

#define subpage_calc_start_bit(fs_info, folio, name, start, len)        \
({                                                                      \
        unsigned int __start_bit;                                       \
        const unsigned int __bpf = btrfs_blocks_per_folio(fs_info, folio); \
                                                                        \
        btrfs_subpage_assert(fs_info, folio, start, len);               \
        __start_bit = offset_in_folio(folio, start) >> fs_info->sectorsize_bits; \
        __start_bit += __bpf * btrfs_bitmap_nr_##name;                  \
        __start_bit;                                                    \
})

static void btrfs_subpage_clamp_range(struct folio *folio, u64 *start, u32 *len)
{
        u64 orig_start = *start;
        u32 orig_len = *len;

        *start = max_t(u64, folio_pos(folio), 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 (folio_pos(folio) >= orig_start + orig_len)
                *len = 0;
        else
                *len = min_t(u64, folio_next_pos(folio), orig_start + orig_len) - *start;
}

static bool btrfs_subpage_end_and_test_lock(const struct btrfs_fs_info *fs_info,
                                            struct folio *folio, u64 start, u32 len)
{
        struct btrfs_folio_state *bfs = folio_get_private(folio);
        const int start_bit = subpage_calc_start_bit(fs_info, folio, locked, start, len);
        const int nbits = (len >> fs_info->sectorsize_bits);
        unsigned long flags;
        unsigned int cleared = 0;
        int bit = start_bit;
        bool last;

        btrfs_subpage_assert(fs_info, folio, start, len);

        spin_lock_irqsave(&bfs->lock, flags);
        /*
         * 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::locked is 0.  Handle them in a special way.
         */
        if (atomic_read(&bfs->nr_locked) == 0) {
                spin_unlock_irqrestore(&bfs->lock, flags);
                return true;
        }

        for_each_set_bit_from(bit, bfs->bitmaps, start_bit + nbits) {
                clear_bit(bit, bfs->bitmaps);
                cleared++;
        }
        ASSERT(atomic_read(&bfs->nr_locked) >= cleared,
               "atomic_read(&bfs->nr_locked)=%d cleared=%d",
               atomic_read(&bfs->nr_locked), cleared);
        last = atomic_sub_and_test(cleared, &bfs->nr_locked);
        spin_unlock_irqrestore(&bfs->lock, flags);
        return last;
}

/*
 * Handle different locked folios:
 *
 * - Non-subpage folio
 *   Just unlock it.
 *
 * - folio locked but without any subpage locked
 *   This happens either before writepage_delalloc() or the delalloc range is
 *   already handled by previous folio.
 *   We can simple unlock it.
 *
 * - folio locked with subpage range locked.
 *   We go through the locked sectors inside the range and clear their locked
 *   bitmap, reduce the writer lock number, and unlock the page if that's
 *   the last locked range.
 */
void btrfs_folio_end_lock(const struct btrfs_fs_info *fs_info,
                          struct folio *folio, u64 start, u32 len)
{
        struct btrfs_folio_state *bfs = folio_get_private(folio);

        ASSERT(folio_test_locked(folio));

        if (unlikely(!fs_info) || !btrfs_is_subpage(fs_info, folio)) {
                folio_unlock(folio);
                return;
        }

        /*
         * For subpage case, there are two types of locked page.  With or
         * without locked number.
         *
         * Since we own the page lock, no one else could touch subpage::locked
         * and we are safe to do several atomic operations without spinlock.
         */
        if (atomic_read(&bfs->nr_locked) == 0) {
                /* No subpage lock, locked by plain lock_page(). */
                folio_unlock(folio);
                return;
        }

        btrfs_subpage_clamp_range(folio, &start, &len);
        if (btrfs_subpage_end_and_test_lock(fs_info, folio, start, len))
                folio_unlock(folio);
}

void btrfs_folio_end_lock_bitmap(const struct btrfs_fs_info *fs_info,
                                 struct folio *folio, unsigned long bitmap)
{
        struct btrfs_folio_state *bfs = folio_get_private(folio);
        const unsigned int blocks_per_folio = btrfs_blocks_per_folio(fs_info, folio);
        const int start_bit = blocks_per_folio * btrfs_bitmap_nr_locked;
        unsigned long flags;
        bool last = false;
        int cleared = 0;
        int bit;

        if (!btrfs_is_subpage(fs_info, folio)) {
                folio_unlock(folio);
                return;
        }

        if (atomic_read(&bfs->nr_locked) == 0) {
                /* No subpage lock, locked by plain lock_page(). */
                folio_unlock(folio);
                return;
        }

        spin_lock_irqsave(&bfs->lock, flags);
        for_each_set_bit(bit, &bitmap, blocks_per_folio) {
                if (test_and_clear_bit(bit + start_bit, bfs->bitmaps))
                        cleared++;
        }
        ASSERT(atomic_read(&bfs->nr_locked) >= cleared,
               "atomic_read(&bfs->nr_locked)=%d cleared=%d",
               atomic_read(&bfs->nr_locked), cleared);
        last = atomic_sub_and_test(cleared, &bfs->nr_locked);
        spin_unlock_irqrestore(&bfs->lock, flags);
        if (last)
                folio_unlock(folio);
}

#define subpage_test_bitmap_all_set(fs_info, folio, name)               \
({                                                                      \
        struct btrfs_folio_state *__bfs = folio_get_private(folio);     \
        const unsigned int __bpf = btrfs_blocks_per_folio(fs_info, folio); \
                                                                        \
        bitmap_test_range_all_set(__bfs->bitmaps,                       \
                                  __bpf * btrfs_bitmap_nr_##name, __bpf); \
})

#define subpage_test_bitmap_all_zero(fs_info, folio, name)              \
({                                                                      \
        struct btrfs_folio_state *__bfs = folio_get_private(folio);     \
        const unsigned int __bpf = btrfs_blocks_per_folio(fs_info, folio); \
                                                                        \
        bitmap_test_range_all_zero(__bfs->bitmaps,                      \
                                   __bpf * btrfs_bitmap_nr_##name, __bpf); \
})

void btrfs_subpage_set_uptodate(const struct btrfs_fs_info *fs_info,
                                struct folio *folio, u64 start, u32 len)
{
        struct btrfs_folio_state *bfs = folio_get_private(folio);
        unsigned int start_bit = subpage_calc_start_bit(fs_info, folio,
                                                        uptodate, start, len);
        unsigned long flags;

        spin_lock_irqsave(&bfs->lock, flags);
        bitmap_set(bfs->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
        if (subpage_test_bitmap_all_set(fs_info, folio, uptodate))
                folio_mark_uptodate(folio);
        spin_unlock_irqrestore(&bfs->lock, flags);
}

void btrfs_subpage_clear_uptodate(const struct btrfs_fs_info *fs_info,
                                  struct folio *folio, u64 start, u32 len)
{
        struct btrfs_folio_state *bfs = folio_get_private(folio);
        unsigned int start_bit = subpage_calc_start_bit(fs_info, folio,
                                                        uptodate, start, len);
        unsigned long flags;

        spin_lock_irqsave(&bfs->lock, flags);
        bitmap_clear(bfs->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
        folio_clear_uptodate(folio);
        spin_unlock_irqrestore(&bfs->lock, flags);
}

void btrfs_subpage_set_dirty(const struct btrfs_fs_info *fs_info,
                             struct folio *folio, u64 start, u32 len)
{
        struct btrfs_folio_state *bfs = folio_get_private(folio);
        unsigned int start_bit = subpage_calc_start_bit(fs_info, folio,
                                                        dirty, start, len);
        unsigned long flags;

        spin_lock_irqsave(&bfs->lock, flags);
        bitmap_set(bfs->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
        spin_unlock_irqrestore(&bfs->lock, flags);
        folio_mark_dirty(folio);
}

/*
 * 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 folio *folio, u64 start, u32 len)
{
        struct btrfs_folio_state *bfs = folio_get_private(folio);
        unsigned int start_bit = subpage_calc_start_bit(fs_info, folio,
                                                        dirty, start, len);
        unsigned long flags;
        bool last = false;

        spin_lock_irqsave(&bfs->lock, flags);
        bitmap_clear(bfs->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
        if (subpage_test_bitmap_all_zero(fs_info, folio, dirty))
                last = true;
        spin_unlock_irqrestore(&bfs->lock, flags);
        return last;
}

void btrfs_subpage_clear_dirty(const struct btrfs_fs_info *fs_info,
                               struct folio *folio, u64 start, u32 len)
{
        bool last;

        last = btrfs_subpage_clear_and_test_dirty(fs_info, folio, start, len);
        if (last)
                folio_clear_dirty_for_io(folio);
}

void btrfs_subpage_set_writeback(const struct btrfs_fs_info *fs_info,
                                 struct folio *folio, u64 start, u32 len)
{
        struct btrfs_folio_state *bfs = folio_get_private(folio);
        unsigned int start_bit = subpage_calc_start_bit(fs_info, folio,
                                                        writeback, start, len);
        unsigned long flags;
        bool keep_write;

        spin_lock_irqsave(&bfs->lock, flags);
        bitmap_set(bfs->bitmaps, start_bit, len >> fs_info->sectorsize_bits);

        /*
         * Don't clear the TOWRITE tag when starting writeback on a still-dirty
         * folio. Doing so can cause WB_SYNC_ALL writepages() to overlook it,
         * assume writeback is complete, and exit too early — violating sync
         * ordering guarantees.
         */
        keep_write = folio_test_dirty(folio);
        if (!folio_test_writeback(folio))
                __folio_start_writeback(folio, keep_write);
        spin_unlock_irqrestore(&bfs->lock, flags);
}

void btrfs_subpage_clear_writeback(const struct btrfs_fs_info *fs_info,
                                   struct folio *folio, u64 start, u32 len)
{
        struct btrfs_folio_state *bfs = folio_get_private(folio);
        unsigned int start_bit = subpage_calc_start_bit(fs_info, folio,
                                                        writeback, start, len);
        unsigned long flags;

        spin_lock_irqsave(&bfs->lock, flags);
        bitmap_clear(bfs->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
        if (subpage_test_bitmap_all_zero(fs_info, folio, writeback)) {
                ASSERT(folio_test_writeback(folio));
                folio_end_writeback(folio);
        }
        spin_unlock_irqrestore(&bfs->lock, flags);
}

void btrfs_subpage_set_ordered(const struct btrfs_fs_info *fs_info,
                               struct folio *folio, u64 start, u32 len)
{
        struct btrfs_folio_state *bfs = folio_get_private(folio);
        unsigned int start_bit = subpage_calc_start_bit(fs_info, folio,
                                                        ordered, start, len);
        unsigned long flags;

        spin_lock_irqsave(&bfs->lock, flags);
        bitmap_set(bfs->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
        folio_set_ordered(folio);
        spin_unlock_irqrestore(&bfs->lock, flags);
}

void btrfs_subpage_clear_ordered(const struct btrfs_fs_info *fs_info,
                                 struct folio *folio, u64 start, u32 len)
{
        struct btrfs_folio_state *bfs = folio_get_private(folio);
        unsigned int start_bit = subpage_calc_start_bit(fs_info, folio,
                                                        ordered, start, len);
        unsigned long flags;

        spin_lock_irqsave(&bfs->lock, flags);
        bitmap_clear(bfs->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
        if (subpage_test_bitmap_all_zero(fs_info, folio, ordered))
                folio_clear_ordered(folio);
        spin_unlock_irqrestore(&bfs->lock, flags);
}

void btrfs_subpage_set_checked(const struct btrfs_fs_info *fs_info,
                               struct folio *folio, u64 start, u32 len)
{
        struct btrfs_folio_state *bfs = folio_get_private(folio);
        unsigned int start_bit = subpage_calc_start_bit(fs_info, folio,
                                                        checked, start, len);
        unsigned long flags;

        spin_lock_irqsave(&bfs->lock, flags);
        bitmap_set(bfs->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
        if (subpage_test_bitmap_all_set(fs_info, folio, checked))
                folio_set_checked(folio);
        spin_unlock_irqrestore(&bfs->lock, flags);
}

void btrfs_subpage_clear_checked(const struct btrfs_fs_info *fs_info,
                                 struct folio *folio, u64 start, u32 len)
{
        struct btrfs_folio_state *bfs = folio_get_private(folio);
        unsigned int start_bit = subpage_calc_start_bit(fs_info, folio,
                                                        checked, start, len);
        unsigned long flags;

        spin_lock_irqsave(&bfs->lock, flags);
        bitmap_clear(bfs->bitmaps, start_bit, len >> fs_info->sectorsize_bits);
        folio_clear_checked(folio);
        spin_unlock_irqrestore(&bfs->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 folio *folio, u64 start, u32 len) \
{                                                                       \
        struct btrfs_folio_state *bfs = folio_get_private(folio);       \
        unsigned int start_bit = subpage_calc_start_bit(fs_info, folio, \
                                                name, start, len);      \
        unsigned long flags;                                            \
        bool ret;                                                       \
                                                                        \
        spin_lock_irqsave(&bfs->lock, flags);                   \
        ret = bitmap_test_range_all_set(bfs->bitmaps, start_bit,        \
                                len >> fs_info->sectorsize_bits);       \
        spin_unlock_irqrestore(&bfs->lock, flags);                      \
        return ret;                                                     \
}
IMPLEMENT_BTRFS_SUBPAGE_TEST_OP(uptodate);
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, folio_set_func,                  \
                                 folio_clear_func, folio_test_func)     \
void btrfs_folio_set_##name(const struct btrfs_fs_info *fs_info,        \
                            struct folio *folio, u64 start, u32 len)    \
{                                                                       \
        if (unlikely(!fs_info) ||                                       \
            !btrfs_is_subpage(fs_info, folio)) {                        \
                folio_set_func(folio);                                  \
                return;                                                 \
        }                                                               \
        btrfs_subpage_set_##name(fs_info, folio, start, len);           \
}                                                                       \
void btrfs_folio_clear_##name(const struct btrfs_fs_info *fs_info,      \
                              struct folio *folio, u64 start, u32 len)  \
{                                                                       \
        if (unlikely(!fs_info) ||                                       \
            !btrfs_is_subpage(fs_info, folio)) {                        \
                folio_clear_func(folio);                                \
                return;                                                 \
        }                                                               \
        btrfs_subpage_clear_##name(fs_info, folio, start, len);         \
}                                                                       \
bool btrfs_folio_test_##name(const struct btrfs_fs_info *fs_info,       \
                             struct folio *folio, u64 start, u32 len)   \
{                                                                       \
        if (unlikely(!fs_info) ||                                       \
            !btrfs_is_subpage(fs_info, folio))                          \
                return folio_test_func(folio);                          \
        return btrfs_subpage_test_##name(fs_info, folio, start, len);   \
}                                                                       \
void btrfs_folio_clamp_set_##name(const struct btrfs_fs_info *fs_info,  \
                                  struct folio *folio, u64 start, u32 len) \
{                                                                       \
        if (unlikely(!fs_info) ||                                       \
            !btrfs_is_subpage(fs_info, folio)) {                        \
                folio_set_func(folio);                                  \
                return;                                                 \
        }                                                               \
        btrfs_subpage_clamp_range(folio, &start, &len);                 \
        btrfs_subpage_set_##name(fs_info, folio, start, len);           \
}                                                                       \
void btrfs_folio_clamp_clear_##name(const struct btrfs_fs_info *fs_info, \
                                    struct folio *folio, u64 start, u32 len) \
{                                                                       \
        if (unlikely(!fs_info) ||                                       \
            !btrfs_is_subpage(fs_info, folio)) {                        \
                folio_clear_func(folio);                                \
                return;                                                 \
        }                                                               \
        btrfs_subpage_clamp_range(folio, &start, &len);                 \
        btrfs_subpage_clear_##name(fs_info, folio, start, len);         \
}                                                                       \
bool btrfs_folio_clamp_test_##name(const struct btrfs_fs_info *fs_info, \
                                   struct folio *folio, u64 start, u32 len) \
{                                                                       \
        if (unlikely(!fs_info) ||                                       \
            !btrfs_is_subpage(fs_info, folio))                          \
                return folio_test_func(folio);                          \
        btrfs_subpage_clamp_range(folio, &start, &len);                 \
        return btrfs_subpage_test_##name(fs_info, folio, start, len);   \
}                                                                       \
void btrfs_meta_folio_set_##name(struct folio *folio, const struct extent_buffer *eb) \
{                                                                       \
        if (!btrfs_meta_is_subpage(eb->fs_info)) {                      \
                folio_set_func(folio);                                  \
                return;                                                 \
        }                                                               \
        btrfs_subpage_set_##name(eb->fs_info, folio, eb->start, eb->len); \
}                                                                       \
void btrfs_meta_folio_clear_##name(struct folio *folio, const struct extent_buffer *eb) \
{                                                                       \
        if (!btrfs_meta_is_subpage(eb->fs_info)) {                      \
                folio_clear_func(folio);                                \
                return;                                                 \
        }                                                               \
        btrfs_subpage_clear_##name(eb->fs_info, folio, eb->start, eb->len); \
}                                                                       \
bool btrfs_meta_folio_test_##name(struct folio *folio, const struct extent_buffer *eb) \
{                                                                       \
        if (!btrfs_meta_is_subpage(eb->fs_info))                        \
                return folio_test_func(folio);                          \
        return btrfs_subpage_test_##name(eb->fs_info, folio, eb->start, eb->len); \
}
IMPLEMENT_BTRFS_PAGE_OPS(uptodate, folio_mark_uptodate, folio_clear_uptodate,
                         folio_test_uptodate);
IMPLEMENT_BTRFS_PAGE_OPS(dirty, folio_mark_dirty, folio_clear_dirty_for_io,
                         folio_test_dirty);
IMPLEMENT_BTRFS_PAGE_OPS(writeback, folio_start_writeback, folio_end_writeback,
                         folio_test_writeback);
IMPLEMENT_BTRFS_PAGE_OPS(ordered, folio_set_ordered, folio_clear_ordered,
                         folio_test_ordered);
IMPLEMENT_BTRFS_PAGE_OPS(checked, folio_set_checked, folio_clear_checked,
                         folio_test_checked);

#define GET_SUBPAGE_BITMAP(fs_info, folio, name, dst)                   \
{                                                                       \
        const unsigned int __bpf = btrfs_blocks_per_folio(fs_info, folio); \
        const struct btrfs_folio_state *__bfs = folio_get_private(folio); \
                                                                        \
        ASSERT(__bpf <= BITS_PER_LONG);                                 \
        *dst = bitmap_read(__bfs->bitmaps,                              \
                           __bpf * btrfs_bitmap_nr_##name, __bpf);      \
}

#define SUBPAGE_DUMP_BITMAP(fs_info, folio, name, start, len)           \
{                                                                       \
        unsigned long bitmap;                                           \
        const unsigned int __bpf = btrfs_blocks_per_folio(fs_info, folio); \
                                                                        \
        GET_SUBPAGE_BITMAP(fs_info, folio, name, &bitmap);              \
        btrfs_warn(fs_info,                                             \
        "dumping bitmap start=%llu len=%u folio=%llu " #name "_bitmap=%*pbl", \
                   start, len, folio_pos(folio), __bpf, &bitmap);       \
}

/*
 * Make sure not only the page dirty bit is cleared, but also subpage dirty bit
 * is cleared.
 */
void btrfs_folio_assert_not_dirty(const struct btrfs_fs_info *fs_info,
                                  struct folio *folio, u64 start, u32 len)
{
        struct btrfs_folio_state *bfs;
        unsigned int start_bit;
        unsigned int nbits;
        unsigned long flags;

        if (!IS_ENABLED(CONFIG_BTRFS_ASSERT))
                return;

        if (!btrfs_is_subpage(fs_info, folio)) {
                ASSERT(!folio_test_dirty(folio));
                return;
        }

        start_bit = subpage_calc_start_bit(fs_info, folio, dirty, start, len);
        nbits = len >> fs_info->sectorsize_bits;
        bfs = folio_get_private(folio);
        ASSERT(bfs);
        spin_lock_irqsave(&bfs->lock, flags);
        if (unlikely(!bitmap_test_range_all_zero(bfs->bitmaps, start_bit, nbits))) {
                SUBPAGE_DUMP_BITMAP(fs_info, folio, dirty, start, len);
                ASSERT(bitmap_test_range_all_zero(bfs->bitmaps, start_bit, nbits));
        }
        ASSERT(bitmap_test_range_all_zero(bfs->bitmaps, start_bit, nbits));
        spin_unlock_irqrestore(&bfs->lock, flags);
}

/*
 * This is for folio already locked by plain lock_page()/folio_lock(), which
 * doesn't have any subpage awareness.
 *
 * This populates the involved subpage ranges so that subpage helpers can
 * properly unlock them.
 */
void btrfs_folio_set_lock(const struct btrfs_fs_info *fs_info,
                          struct folio *folio, u64 start, u32 len)
{
        struct btrfs_folio_state *bfs;
        unsigned long flags;
        unsigned int start_bit;
        unsigned int nbits;
        int ret;

        ASSERT(folio_test_locked(folio));
        if (unlikely(!fs_info) || !btrfs_is_subpage(fs_info, folio))
                return;

        bfs = folio_get_private(folio);
        start_bit = subpage_calc_start_bit(fs_info, folio, locked, start, len);
        nbits = len >> fs_info->sectorsize_bits;
        spin_lock_irqsave(&bfs->lock, flags);
        /* Target range should not yet be locked. */
        if (unlikely(!bitmap_test_range_all_zero(bfs->bitmaps, start_bit, nbits))) {
                SUBPAGE_DUMP_BITMAP(fs_info, folio, locked, start, len);
                ASSERT(bitmap_test_range_all_zero(bfs->bitmaps, start_bit, nbits));
        }
        bitmap_set(bfs->bitmaps, start_bit, nbits);
        ret = atomic_add_return(nbits, &bfs->nr_locked);
        ASSERT(ret <= btrfs_blocks_per_folio(fs_info, folio));
        spin_unlock_irqrestore(&bfs->lock, flags);
}

/*
 * Clear the dirty flag for the folio.
 *
 * If the affected folio is no longer dirty, return true. Otherwise return false.
 */
bool btrfs_meta_folio_clear_and_test_dirty(struct folio *folio, const struct extent_buffer *eb)
{
        bool last;

        if (!btrfs_meta_is_subpage(eb->fs_info)) {
                folio_clear_dirty_for_io(folio);
                return true;
        }

        last = btrfs_subpage_clear_and_test_dirty(eb->fs_info, folio, eb->start, eb->len);
        if (last) {
                folio_clear_dirty_for_io(folio);
                return true;
        }
        return false;
}

void __cold btrfs_subpage_dump_bitmap(const struct btrfs_fs_info *fs_info,
                                      struct folio *folio, u64 start, u32 len)
{
        struct btrfs_folio_state *bfs;
        const unsigned int blocks_per_folio = btrfs_blocks_per_folio(fs_info, folio);
        unsigned long uptodate_bitmap;
        unsigned long dirty_bitmap;
        unsigned long writeback_bitmap;
        unsigned long ordered_bitmap;
        unsigned long checked_bitmap;
        unsigned long locked_bitmap;
        unsigned long flags;

        ASSERT(folio_test_private(folio) && folio_get_private(folio));
        ASSERT(blocks_per_folio > 1);
        bfs = folio_get_private(folio);

        spin_lock_irqsave(&bfs->lock, flags);
        GET_SUBPAGE_BITMAP(fs_info, folio, uptodate, &uptodate_bitmap);
        GET_SUBPAGE_BITMAP(fs_info, folio, dirty, &dirty_bitmap);
        GET_SUBPAGE_BITMAP(fs_info, folio, writeback, &writeback_bitmap);
        GET_SUBPAGE_BITMAP(fs_info, folio, ordered, &ordered_bitmap);
        GET_SUBPAGE_BITMAP(fs_info, folio, checked, &checked_bitmap);
        GET_SUBPAGE_BITMAP(fs_info, folio, locked, &locked_bitmap);
        spin_unlock_irqrestore(&bfs->lock, flags);

        dump_page(folio_page(folio, 0), "btrfs folio state dump");
        btrfs_warn(fs_info,
"start=%llu len=%u page=%llu, bitmaps uptodate=%*pbl dirty=%*pbl locked=%*pbl writeback=%*pbl ordered=%*pbl checked=%*pbl",
                    start, len, folio_pos(folio),
                    blocks_per_folio, &uptodate_bitmap,
                    blocks_per_folio, &dirty_bitmap,
                    blocks_per_folio, &locked_bitmap,
                    blocks_per_folio, &writeback_bitmap,
                    blocks_per_folio, &ordered_bitmap,
                    blocks_per_folio, &checked_bitmap);
}

void btrfs_get_subpage_dirty_bitmap(struct btrfs_fs_info *fs_info,
                                    struct folio *folio,
                                    unsigned long *ret_bitmap)
{
        struct btrfs_folio_state *bfs;
        unsigned long flags;

        ASSERT(folio_test_private(folio) && folio_get_private(folio));
        ASSERT(btrfs_blocks_per_folio(fs_info, folio) > 1);
        bfs = folio_get_private(folio);

        spin_lock_irqsave(&bfs->lock, flags);
        GET_SUBPAGE_BITMAP(fs_info, folio, dirty, ret_bitmap);
        spin_unlock_irqrestore(&bfs->lock, flags);
}