Re: [PATCH 01/14] f2fs: extend folio state for large folio write path
From: Chao Yu
Date: Thu Aug 27 2026 - 02:58:01 EST
On 8/26/26 16:26, Nanzhe Zhao wrote:
> Large folio write path needs a subpage status bitmap and write
> pages pending counter, while keeping compatible with f2fs private
> flags.
>
> Move struct f2fs_folio_state to f2fs.h, add private_flags and
> subpage state bitmap, and change PAGE_PRIVATE functions to be
> compatible with f2fs_folio_state. Allocate f2fs_folio_state via kzalloc
> instead of kmem_cache, since the state size depends on the folio order.
>
> Note: Now if a path wants to use f2fs_folio_state, it must call
> `folio_has_ffs` instead of `folio_test_large`` to make check.
>
> Signed-off-by: Nanzhe Zhao <zhaonanzhe@xxxxxxxxxx>
> ---
> fs/f2fs/compress.c | 2 +
> fs/f2fs/data.c | 60 ++++++++++++++++--------------
> fs/f2fs/f2fs.h | 92 ++++++++++++++++++++++++++++++++++++----------
> fs/f2fs/segment.c | 2 +-
> 4 files changed, 108 insertions(+), 48 deletions(-)
>
> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
> index 91855d91bbdd..84da3e39efb4 100644
> --- a/fs/f2fs/compress.c
> +++ b/fs/f2fs/compress.c
> @@ -78,6 +78,8 @@ bool f2fs_is_compressed_page(struct folio *folio)
> return false;
> if (folio_test_f2fs_nonpointer(folio))
> return false;
> + if (f2fs_folio_has_ffs(folio))
> + return false;
Shouldn't this be changed in "f2fs: make compressed files compatible with
large folio" or other patch? I guess in this patch we only introduce new
ffs facilities.
>
> f2fs_bug_on(F2FS_F_SB(folio),
> *((u32 *)folio->private) != F2FS_COMPRESSED_PAGE_MAGIC);
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 6ae0eb37d20f..578a90d427e2 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -32,20 +32,13 @@
>
> static struct kmem_cache *bio_post_read_ctx_cache;
> static struct kmem_cache *bio_entry_slab;
> -static struct kmem_cache *ffs_entry_slab;
> static mempool_t *bio_post_read_ctx_pool;
> static struct bio_set f2fs_bioset;
>
> -struct f2fs_folio_state {
> - spinlock_t state_lock;
> - unsigned int read_pages_pending;
> -};
> -
> struct f2fs_bio {
> struct work_struct work;
> struct bio bio;
> };
> -
Unnecessary change.
> #define F2FS_BIO_POOL_SIZE NR_CURSEG_TYPE
>
> int __init f2fs_init_bioset(void)
> @@ -133,6 +126,9 @@ struct bio_post_read_ctx {
> block_t fs_blkaddr;
> };
>
> +static bool __ffs_mark_subrange_uptodate(struct folio *folio,
> + struct f2fs_folio_state *ffs, size_t offset, size_t len);
> +
> /*
> * Update and unlock a bio's pages, and free the bio.
> *
> @@ -155,7 +151,7 @@ static void f2fs_finish_read_bio(struct bio *bio, bool in_task)
>
> bio_for_each_folio_all(fi, bio) {
> struct folio *folio = fi.folio;
> - unsigned nr_pages = fi.length >> PAGE_SHIFT;
> + unsigned int nr_pages = fi.length >> PAGE_SHIFT;
No need to change in this patch?
> bool finished = true;
>
> if (!folio_test_large(folio) &&
> @@ -360,6 +356,7 @@ static void f2fs_write_end_bio(struct bio *bio)
>
> bio_for_each_folio_all(fi, bio) {
> struct folio *folio = fi.folio;
> + unsigned int nr_pages = fi.length >> PAGE_SHIFT;
No need to change in this patch?
> enum count_type type;
>
> if (fscrypt_is_bounce_folio(folio)) {
> @@ -2516,17 +2513,32 @@ int f2fs_read_multi_pages(struct compress_ctx *cc, struct bio **bio_ret,
> }
> #endif
>
> -static struct f2fs_folio_state *ffs_find_or_alloc(struct folio *folio)
> +struct f2fs_folio_state *f2fs_ffs_find_or_alloc(struct folio *folio)
> {
> - struct f2fs_folio_state *ffs = folio->private;
> + struct f2fs_folio_state *ffs;
> + unsigned int nr_subpages = folio_nr_pages(folio);
> + unsigned long private_flags = 0;
> +
> + f2fs_bug_on(F2FS_F_SB(folio), !folio_test_large(folio));
>
> - if (ffs)
> - return ffs;
> + if (f2fs_folio_has_ffs(folio))
> + return (struct f2fs_folio_state *)folio->private;
>
> - ffs = f2fs_kmem_cache_alloc(ffs_entry_slab,
> - GFP_NOIO | __GFP_ZERO, true, NULL);
> + if (folio_test_private(folio) && folio_test_f2fs_nonpointer(folio))
> + private_flags = (unsigned long)folio->private;
> +
> + ffs = kzalloc(struct_size(ffs, state, BITS_TO_LONGS(2 * nr_subpages)),
> + GFP_NOIO | __GFP_NOFAIL);
>
> spin_lock_init(&ffs->state_lock);
> + ffs->private_flags = private_flags;
> + if (folio_test_uptodate(folio))
> + bitmap_set(ffs->state, 0, nr_subpages);
> + if (folio_test_dirty(folio))
> + bitmap_set(ffs->state, nr_subpages, nr_subpages);
> +
> + if (folio_test_private(folio))
> + folio_detach_private(folio);
> folio_attach_private(folio, ffs);
> return ffs;
> }
> @@ -2535,7 +2547,7 @@ static void ffs_detach_free(struct folio *folio)
> {
> struct f2fs_folio_state *ffs;
>
> - if (!folio_test_large(folio)) {
> + if (!f2fs_folio_has_ffs(folio)) {
> folio_detach_private(folio);
> return;
> }
> @@ -2545,7 +2557,8 @@ static void ffs_detach_free(struct folio *folio)
> return;
>
> WARN_ON_ONCE(ffs->read_pages_pending != 0);
> - kmem_cache_free(ffs_entry_slab, ffs);
> + WARN_ON_ONCE(atomic_read(&ffs->write_pages_pending));
> + kfree(ffs);
> }
>
> static int f2fs_read_data_large_folio(struct inode *inode,
> @@ -2558,7 +2571,7 @@ static int f2fs_read_data_large_folio(struct inode *inode,
> pgoff_t index, offset, next_pgofs = 0;
> unsigned max_nr_pages = rac ? readahead_count(rac) :
> folio_nr_pages(folio);
> - unsigned nrpages;
> + unsigned int nrpages, len_blks;
> struct f2fs_folio_state *ffs;
> int ret = 0;
> bool folio_in_bio = false;
> @@ -2634,7 +2647,7 @@ static int f2fs_read_data_large_folio(struct inode *inode,
> * to prevent from premature folio_end_read() call on folio
> */
> if (folio_test_large(folio)) {
> - ffs = ffs_find_or_alloc(folio);
> + ffs = f2fs_ffs_find_or_alloc(folio);
>
> /* set the bitmap to wait */
> spin_lock_irq(&ffs->state_lock);
> @@ -2987,7 +3000,7 @@ bool f2fs_should_update_outplace(struct inode *inode, struct f2fs_io_info *fio)
> return true;
>
> if (fio) {
> - if (page_private_gcing(fio->page))
> + if (folio_test_f2fs_gcing(fio->folio))
Shouldn't this be changed in "f2fs: make GC migration large-folio aware"?
> return true;
> if (unlikely(is_sbi_flag_set(sbi, SBI_CP_DISABLED) &&
> f2fs_is_checkpointed_data(sbi, fio->old_blkaddr)))
> @@ -4586,21 +4599,12 @@ int __init f2fs_init_bio_entry_cache(void)
> if (!bio_entry_slab)
> return -ENOMEM;
>
> - ffs_entry_slab = f2fs_kmem_cache_create("f2fs_ffs_slab",
> - sizeof(struct f2fs_folio_state));
> -
> - if (!ffs_entry_slab) {
> - kmem_cache_destroy(bio_entry_slab);
> - return -ENOMEM;
> - }
> -
> return 0;
> }
>
> void f2fs_destroy_bio_entry_cache(void)
> {
> kmem_cache_destroy(bio_entry_slab);
> - kmem_cache_destroy(ffs_entry_slab);
> }
>
> static int f2fs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 16720f1f0a9c..2e8f85cea6d0 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -1628,6 +1628,18 @@ static inline void f2fs_clear_bit(unsigned int nr, char *addr);
> * Layout B: lowest bit should be 0
> * page.private is a wrapped pointer.
> */
> +
> +struct f2fs_folio_state {
> + spinlock_t state_lock;
> + unsigned int read_pages_pending;
> + atomic_t write_pages_pending;
> + unsigned long private_flags;
> + /* state[0..nr_subpages - 1] tracks uptodate subpages.
> + * state[nr_subpages..2 * nr_subpages - 1] tracks dirty subpages.
> + */
> + unsigned long state[];
> +};
> +
> enum {
> PAGE_PRIVATE_NOT_POINTER, /* private contains non-pointer data */
> PAGE_PRIVATE_ONGOING_MIGRATION, /* data page which is on-going migrating */
> @@ -1637,6 +1649,14 @@ enum {
> PAGE_PRIVATE_MAX
> };
>
> +static inline bool f2fs_folio_has_ffs(const struct folio *folio)
> +{
> + unsigned long private = (unsigned long)folio->private;
> +
> + return folio_test_large(folio) && private &&
> + !(private & BIT(PAGE_PRIVATE_NOT_POINTER));
Is this a bug? in which case we will set PAGE_PRIVATE_NOT_POINTER in
a large folio? maybe I missed some cases...
folio_test_large(folio) && private is true and
(private & BIT(PAGE_PRIVATE_NOT_POINTER) is true?
> +}
> +
> /* For compression */
> enum compress_algorithm_type {
> COMPRESS_LZO,
> @@ -2682,10 +2702,57 @@ static inline int inc_valid_block_count(struct f2fs_sb_info *sbi,
> return -ENOSPC;
> }
>
> +static inline unsigned long f2fs_folio_get_private_flags(const struct folio *folio)
> +{
> + if (f2fs_folio_has_ffs(folio)) {
> + struct f2fs_folio_state *ffs = folio->private;
> +
> + return ffs->private_flags;
> + }
> +
> + return (unsigned long)folio->private;
> +}
> +
> +static inline void f2fs_folio_set_private_flags(struct folio *folio,
> + unsigned long flags)
> +{
> + if (f2fs_folio_has_ffs(folio)) {
> + struct f2fs_folio_state *ffs = folio->private;
> +
> + ffs->private_flags |= flags;
> + return;
> + }
> +
> + if (!folio_test_private(folio))
> + folio_attach_private(folio, (void *)flags);
> + else
> + folio->private = (void *)((unsigned long)folio->private | flags);
> +}
> +
> +static inline void f2fs_folio_clear_private_flags(struct folio *folio,
> + unsigned long flags)
> +{
> + unsigned long private;
> +
> + if (f2fs_folio_has_ffs(folio)) {
> + struct f2fs_folio_state *ffs = folio->private;
> +
> + ffs->private_flags &= ~flags;
> + return;
> + }
> +
> + private = (unsigned long)folio->private;
> + private &= ~flags;
> + if (private == BIT(PAGE_PRIVATE_NOT_POINTER))
> + folio_detach_private(folio);
> + else
> + folio->private = (void *)private;
> +}
> +
> #define PAGE_PRIVATE_GET_FUNC(name, flagname) \
> static inline bool folio_test_f2fs_##name(const struct folio *folio) \
> { \
> - unsigned long priv = (unsigned long)folio->private; \
> + unsigned long priv = f2fs_folio_get_private_flags(folio); \
> unsigned long v = (1UL << PAGE_PRIVATE_NOT_POINTER) | \
> (1UL << PAGE_PRIVATE_##flagname); \
> return (priv & v) == v; \
> @@ -2702,12 +2769,7 @@ static inline void folio_set_f2fs_##name(struct folio *folio) \
> { \
> unsigned long v = (1UL << PAGE_PRIVATE_NOT_POINTER) | \
> (1UL << PAGE_PRIVATE_##flagname); \
> - if (!folio->private) \
> - folio_attach_private(folio, (void *)v); \
> - else { \
> - v |= (unsigned long)folio->private; \
> - folio->private = (void *)v; \
> - } \
> + f2fs_folio_set_private_flags(folio, v); \
> } \
> static inline void set_page_private_##name(struct page *page) \
> { \
> @@ -2720,13 +2782,8 @@ static inline void set_page_private_##name(struct page *page) \
> #define PAGE_PRIVATE_CLEAR_FUNC(name, flagname) \
> static inline void folio_clear_f2fs_##name(struct folio *folio) \
> { \
> - unsigned long v = (unsigned long)folio->private; \
> - \
> - v &= ~(1UL << PAGE_PRIVATE_##flagname); \
> - if (v == (1UL << PAGE_PRIVATE_NOT_POINTER)) \
> - folio_detach_private(folio); \
> - else \
> - folio->private = (void *)v; \
> + f2fs_folio_clear_private_flags(folio, \
> + 1UL << PAGE_PRIVATE_##flagname); \
> } \
> static inline void clear_page_private_##name(struct page *page) \
> { \
> @@ -2752,7 +2809,7 @@ PAGE_PRIVATE_CLEAR_FUNC(atomic, ATOMIC_WRITE);
>
> static inline unsigned long folio_get_f2fs_data(struct folio *folio)
> {
> - unsigned long data = (unsigned long)folio->private;
> + unsigned long data = f2fs_folio_get_private_flags(folio);
>
> if (!test_bit(PAGE_PRIVATE_NOT_POINTER, &data))
> return 0;
> @@ -2763,10 +2820,7 @@ static inline void folio_set_f2fs_data(struct folio *folio, unsigned long data)
> {
> data = (1UL << PAGE_PRIVATE_NOT_POINTER) | (data << PAGE_PRIVATE_MAX);
>
> - if (!folio_test_private(folio))
> - folio_attach_private(folio, (void *)data);
> - else
> - folio->private = (void *)((unsigned long)folio->private | data);
> + f2fs_folio_set_private_flags(folio, data);
> }
>
> static inline void dec_valid_block_count(struct f2fs_sb_info *sbi,
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index ed6f2947210b..df10119d94ad 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -3803,7 +3803,7 @@ static int __get_segment_type_6(struct f2fs_io_info *fio)
> if (is_inode_flag_set(inode, FI_ALIGNED_WRITE))
> return CURSEG_COLD_DATA_PINNED;
>
> - if (page_private_gcing(fio->page)) {
> + if (folio_test_f2fs_gcing(fio->folio)) {
Shouldn't this be changed in "f2fs: make GC migration large-folio aware"?
Thanks,
> if (fio->sbi->am.atgc_enabled &&
> (fio->io_type == FS_DATA_IO) &&
> (fio->sbi->gc_mode != GC_URGENT_HIGH) &&