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Message-ID: <aSEPFuGCqSIHguL5@google.com>
Date: Sat, 22 Nov 2025 01:17:10 +0000
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <chao@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH 1/2] f2fs: support large folio for immutable
non-compressed case
On 11/21, Chao Yu wrote:
> On 11/21/2025 7:54 AM, Jaegeuk Kim via Linux-f2fs-devel wrote:
> > This patch enables large folio for limited case where we can get the high-order
> > memory allocation. It supports the encrypted and fsverity files, which are
> > essential for Android environment.
> >
> > How to test:
> > - dd if=/dev/zero of=/mnt/test/test bs=1G count=4
> > - f2fs_io setflags immutable /mnt/test/test
> > - echo 3 > /proc/sys/vm/drop_caches
> > : to reload inode with large folio
> > - f2fs_io read 32 0 1024 mmap 0 0 /mnt/test/test
> >
> > Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
> > ---
> > fs/f2fs/data.c | 245 ++++++++++++++++++++++++++++++++++++++++++++++--
> > fs/f2fs/f2fs.h | 16 ++++
> > fs/f2fs/inode.c | 6 +-
> > 3 files changed, 257 insertions(+), 10 deletions(-)
> >
> > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> > index 48c20386f031..8f433677c49d 100644
> > --- a/fs/f2fs/data.c
> > +++ b/fs/f2fs/data.c
> > @@ -31,9 +31,15 @@
> > 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;
> > +};
> > +
> > #define F2FS_BIO_POOL_SIZE NR_CURSEG_TYPE
> > int __init f2fs_init_bioset(void)
> > @@ -138,11 +144,15 @@ static void f2fs_finish_read_bio(struct bio *bio, bool in_task)
> > {
> > struct folio_iter fi;
> > struct bio_post_read_ctx *ctx = bio->bi_private;
> > + unsigned long flags;
> > bio_for_each_folio_all(fi, bio) {
> > struct folio *folio = fi.folio;
> > + unsigned nr_pages = fi.length >> PAGE_SHIFT;
> > + bool finished = true;
> > - if (f2fs_is_compressed_page(folio)) {
> > + if (!folio_test_large(folio) &&
> > + f2fs_is_compressed_page(folio)) {
> > if (ctx && !ctx->decompression_attempted)
> > f2fs_end_read_compressed_page(folio, true, 0,
> > in_task);
> > @@ -156,8 +166,20 @@ static void f2fs_finish_read_bio(struct bio *bio, bool in_task)
> > bio->bi_status = BLK_STS_IOERR;
> > }
> > - dec_page_count(F2FS_F_SB(folio), __read_io_type(folio));
> > - folio_end_read(folio, bio->bi_status == BLK_STS_OK);
> > + if (folio_test_large(folio)) {
> > + struct f2fs_folio_state *ffs = folio->private;
> > +
> > + spin_lock_irqsave(&ffs->state_lock, flags);
> > + ffs->read_pages_pending -= nr_pages;
> > + finished = !ffs->read_pages_pending;
> > + spin_unlock_irqrestore(&ffs->state_lock, flags);
> > + }
> > +
> > + while (nr_pages--)
> > + dec_page_count(F2FS_F_SB(folio), __read_io_type(folio));
> > +
> > + if (finished)
> > + folio_end_read(folio, bio->bi_status == BLK_STS_OK);
> > }
> > if (ctx)
> > @@ -518,6 +540,9 @@ static bool f2fs_crypt_mergeable_bio(struct bio *bio, const struct inode *inode,
> > void f2fs_submit_read_bio(struct f2fs_sb_info *sbi, struct bio *bio,
> > enum page_type type)
> > {
> > + if (!bio)
> > + return;
> > +
> > WARN_ON_ONCE(!is_read_io(bio_op(bio)));
> > trace_f2fs_submit_read_bio(sbi->sb, type, bio);
> > @@ -1209,11 +1234,21 @@ struct folio *f2fs_get_read_data_folio(struct inode *inode, pgoff_t index,
> > struct dnode_of_data dn;
> > struct folio *folio;
> > int err;
> > -
> > +retry:
> > folio = f2fs_grab_cache_folio(mapping, index, for_write);
> > if (IS_ERR(folio))
> > return folio;
> > + if (folio_test_large(folio)) {
> > + pgoff_t folio_index = mapping_align_index(mapping, index);
> > +
> > + f2fs_folio_put(folio, true);
> > + invalidate_inode_pages2_range(mapping, folio_index,
> > + folio_index + folio_nr_pages(folio) - 1);
> > + f2fs_schedule_timeout(DEFAULT_SCHEDULE_TIMEOUT);
> > + goto retry;
> > + }
>
> Do we need to move above check into f2fs_grab_cache_folio()? as we call
> f2fs_grab_cache_folio() in a lot of place.
We're okay with high-order allocation in other path, but I think this is
the only problem since it goes to GC writes.
>
> > +
> > if (f2fs_lookup_read_extent_cache_block(inode, index,
> > &dn.data_blkaddr)) {
> > if (!f2fs_is_valid_blkaddr(F2FS_I_SB(inode), dn.data_blkaddr,
> > @@ -2341,6 +2376,177 @@ 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 *ffs = folio->private;
> > +
> > + if (ffs)
> > + return ffs;
> > +
> > + ffs = f2fs_kmem_cache_alloc(ffs_entry_slab, GFP_NOIO, true, NULL);
> > +
> > + spin_lock_init(&ffs->state_lock);
> > + folio_attach_private(folio, ffs);
> > + return ffs;
> > +}
> > +
> > +static void ffs_detach_free(struct folio *folio)
> > +{
> > + struct f2fs_folio_state *ffs;
> > +
> > + if (!folio_test_large(folio)) {
> > + folio_detach_private(folio);
> > + return;
> > + }
> > +
> > + ffs = folio_detach_private(folio);
> > + if (!ffs)
> > + return;
> > +
> > + WARN_ON_ONCE(ffs->read_pages_pending != 0);
> > + kmem_cache_free(ffs_entry_slab, ffs);
> > +}
> > +
> > +static int f2fs_read_data_large_folio(struct inode *inode,
> > + struct readahead_control *rac, struct folio *folio)
> > +{
> > + struct bio *bio = NULL;
> > + sector_t last_block_in_bio = 0;
> > + struct f2fs_map_blocks map;
> > + pgoff_t index, offset;> + unsigned max_nr_pages = rac ? readahead_count(rac) :
> > + folio_nr_pages(folio);
> > + unsigned nrpages;
> > + struct f2fs_folio_state *ffs;
> > + int ret = 0;
> > +
> > + if (f2fs_compressed_file(inode))
> > + return -EOPNOTSUPP;
>
> if (!IS_IMMUTABLE(inode))
> return -EOPNOTSUPP;
>
> We can configure inode after this check? Can we add some sanity check to prevent
> enabling compress/immutable/quota if inode has already enabled large folio?
I think immutable will prevent most of the changes?
>
> > +
> > + memset(&map, 0, sizeof(map));
>
> Can be replaced w/ struct f2fs_map_blocks map = {0, };
>
> > + map.m_seg_type = NO_CHECK_TYPE;
> > +
> > + if (rac)
> > + folio = readahead_folio(rac);
> > +next_folio:
> > + if (!folio)
> > + goto out;
> > +
> > + index = folio->index;
> > + offset = 0;
> > + ffs = NULL;
> > + nrpages = folio_nr_pages(folio);
> > +
> > + for (; nrpages; nrpages--) {
> > + sector_t block_nr;
> > + /*
> > + * Map blocks using the previous result first.
> > + */
> > + if ((map.m_flags & F2FS_MAP_MAPPED) &&
> > + index > map.m_lblk &&
> > + index < (map.m_lblk + map.m_len))
> > + goto got_it;
> > +
> > + /*
> > + * Then do more f2fs_map_blocks() calls until we are
> > + * done with this page.
> > + */
> > + memset(&map, 0, sizeof(map));
> > + map.m_seg_type = NO_CHECK_TYPE;
> > + map.m_lblk = index;
> > + map.m_len = max_nr_pages;
> > +
> > + ret = f2fs_map_blocks(inode, &map, F2FS_GET_BLOCK_DEFAULT);
> > + if (ret)
> > + goto err_out;
> > +got_it:
> > + if ((map.m_flags & F2FS_MAP_MAPPED)) {
> > + block_nr = map.m_pblk + index - map.m_lblk;
> > + if (!f2fs_is_valid_blkaddr(F2FS_I_SB(inode), block_nr,
> > + DATA_GENERIC_ENHANCE_READ)) {
> > + ret = -EFSCORRUPTED;
> > + goto err_out;
> > + }
> > + } else {
> > + folio_zero_range(folio, offset << PAGE_SHIFT, PAGE_SIZE);
> > + if (f2fs_need_verity(inode, index) &&
> > + !fsverity_verify_page(folio_file_page(folio,
> > + index))) {
> > + ret = -EIO;
> > + goto err_out;
> > + }
> > + continue;
> > + }
> > +
> > + /*
> > + * This page will go to BIO. Do we need to send this
> > + * BIO off first?
> > + */
> > + if (bio && (!page_is_mergeable(F2FS_I_SB(inode), bio,
> > + last_block_in_bio, block_nr) ||
> > + !f2fs_crypt_mergeable_bio(bio, inode, index, NULL))) {
> > +submit_and_realloc:
> > + f2fs_submit_read_bio(F2FS_I_SB(inode), bio, DATA);
> > + bio = NULL;
> > + }
> > + if (bio == NULL)
> > + bio = f2fs_grab_read_bio(inode, block_nr,
> > + max_nr_pages,
> > + f2fs_ra_op_flags(rac),
> > + index, false);
> > +
> > + /*
> > + * If the page is under writeback, we need to wait for
> > + * its completion to see the correct decrypted data.
> > + */
> > + f2fs_wait_on_block_writeback(inode, block_nr);
> > +
> > + if (!bio_add_folio(bio, folio, F2FS_BLKSIZE,
> > + offset << PAGE_SHIFT))> + goto submit_and_realloc;
> > +
> > + if (folio_test_large(folio)) {
> > + ffs = ffs_find_or_alloc(folio);
> > +
> > + /* set the bitmap to wait */
> > + spin_lock_irq(&ffs->state_lock);
> > + ffs->read_pages_pending++;
> > + spin_unlock_irq(&ffs->state_lock);
> > + }
> > +
> > + inc_page_count(F2FS_I_SB(inode), F2FS_RD_DATA);
> > + f2fs_update_iostat(F2FS_I_SB(inode), NULL, FS_DATA_READ_IO,
> > + F2FS_BLKSIZE);
> > + last_block_in_bio = block_nr;
> > + index++;
> > + offset++;
> > + }
> > + if (rac) {
> > + folio = readahead_folio(rac);
> > + goto next_folio;
> > + }
> > +err_out:
> > + /* Nothing was submitted. */
> > + if (!bio) {
> > + if (!ret)
> > + folio_mark_uptodate(folio);
> > + folio_unlock(folio);
> > + return ret;
> > + }
> > +
> > + if (ret) {
> > + f2fs_submit_read_bio(F2FS_I_SB(inode), bio, DATA);
> > +
> > + /* Wait bios and clear uptodate. */
> > + folio_lock(folio);
> > + folio_clear_uptodate(folio);
> > + folio_unlock(folio);
> > + }
> > +out:
> > + f2fs_submit_read_bio(F2FS_I_SB(inode), bio, DATA);
> > + return ret;
> > +}
> > +
> > /*
> > * This function was originally taken from fs/mpage.c, and customized for f2fs.
> > * Major change was from block_size == page_size in f2fs by default.
> > @@ -2366,9 +2572,13 @@ static int f2fs_mpage_readpages(struct inode *inode,
> > pgoff_t index;
> > #endif
> > unsigned nr_pages = rac ? readahead_count(rac) : 1;
> > + struct address_space *mapping = rac ? rac->mapping : folio->mapping;
> > unsigned max_nr_pages = nr_pages;
> > int ret = 0;
> > + if (mapping_large_folio_support(mapping))
> > + return f2fs_read_data_large_folio(inode, rac, folio);
> > +
> > #ifdef CONFIG_F2FS_FS_COMPRESSION
> > if (f2fs_compressed_file(inode)) {
> > index = rac ? readahead_index(rac) : folio->index;
> > @@ -2459,8 +2669,7 @@ static int f2fs_mpage_readpages(struct inode *inode,
> > }
> > #endif
> > }
> > - if (bio)
> > - f2fs_submit_read_bio(F2FS_I_SB(inode), bio, DATA);
> > + f2fs_submit_read_bio(F2FS_I_SB(inode), bio, DATA);
> > return ret;
> > }
> > @@ -3747,7 +3956,12 @@ void f2fs_invalidate_folio(struct folio *folio, size_t offset, size_t length)
> > f2fs_remove_dirty_inode(inode);
> > }
> > }
> > - folio_detach_private(folio);
> > +
> > + if (offset || length != folio_size(folio))
> > + return;
> > +
> > + folio_cancel_dirty(folio);
> > + ffs_detach_free(folio);
> > }
> > bool f2fs_release_folio(struct folio *folio, gfp_t wait)
> > @@ -3756,7 +3970,7 @@ bool f2fs_release_folio(struct folio *folio, gfp_t wait)
> > if (folio_test_dirty(folio))
> > return false;
> > - folio_detach_private(folio);
> > + ffs_detach_free(folio);
> > return true;
> > }
> > @@ -4162,12 +4376,25 @@ int __init f2fs_init_bio_entry_cache(void)
> > {
> > bio_entry_slab = f2fs_kmem_cache_create("f2fs_bio_entry_slab",
> > sizeof(struct bio_entry));
> > - return bio_entry_slab ? 0 : -ENOMEM;
> > +
> > + 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 dffe8958b580..3340db04a7c2 100644
> > --- a/fs/f2fs/f2fs.h
> > +++ b/fs/f2fs/f2fs.h
> > @@ -4916,6 +4916,22 @@ static inline bool is_journalled_quota(struct f2fs_sb_info *sbi)
> > return false;
> > }
> > +static inline bool f2fs_quota_file(struct inode *inode)
> > +{
> > +#ifdef CONFIG_QUOTA
> > + int i;
> > +
> > + if (!f2fs_sb_has_quota_ino(F2FS_I_SB(inode)))
> > + return false;
> > +
> > + for (i = 0; i < MAXQUOTAS; i++) {
> > + if (f2fs_qf_ino(F2FS_I_SB(inode)->sb, i) == inode->i_ino)
> > + return true;
> > + }
> > +#endif
> > + return false;
> > +}
> > +
> > static inline bool f2fs_block_unit_discard(struct f2fs_sb_info *sbi)
> > {
> > return F2FS_OPTION(sbi).discard_unit == DISCARD_UNIT_BLOCK;
> > diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
> > index e2405b79b3cc..9162154d5211 100644
> > --- a/fs/f2fs/inode.c
> > +++ b/fs/f2fs/inode.c
> > @@ -597,6 +597,8 @@ struct inode *f2fs_iget(struct super_block *sb, unsigned long ino)
> > if (ret)
> > goto bad_inode;
> > make_now:
> > + f2fs_set_inode_flags(inode);
> > +
> > if (ino == F2FS_NODE_INO(sbi)) {
> > inode->i_mapping->a_ops = &f2fs_node_aops;
> > mapping_set_gfp_mask(inode->i_mapping, GFP_NOFS);
> > @@ -618,6 +620,9 @@ struct inode *f2fs_iget(struct super_block *sb, unsigned long ino)
> > inode->i_op = &f2fs_file_inode_operations;
> > inode->i_fop = &f2fs_file_operations;
> > inode->i_mapping->a_ops = &f2fs_dblock_aops;
> > + if (IS_IMMUTABLE(inode) && !f2fs_compressed_file(inode) &&
> > + !f2fs_quota_file(inode))
> > + mapping_set_folio_min_order(inode->i_mapping, 0);
> > } else if (S_ISDIR(inode->i_mode)) {
> > inode->i_op = &f2fs_dir_inode_operations;
> > inode->i_fop = &f2fs_dir_operations;
> > @@ -638,7 +643,6 @@ struct inode *f2fs_iget(struct super_block *sb, unsigned long ino)
> > ret = -EIO;
> > goto bad_inode;
> > }
> > - f2fs_set_inode_flags(inode);
> > unlock_new_inode(inode);
> > trace_f2fs_iget(inode);
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