i_blocks_per_folio(9)

✨ i_blocks_per_folio(9) ✨

okay so this is a page from the Kernel API Manual, manual section 9 (that's the kernel-API girlies 💅), and it's all about i_blocks_per_folio — literally the function that tells you how many blocks fit in a folio. no cap, that's the whole vibe.

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🌸 NAME 🌸

i_blocks_per_folio — how many blocks fit in this folio. that's it, that's the gig 🎀

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🦋 SYNOPSIS 🦋

unsigned int i_blocks_per_folio (const struct inode *inode , const
       struct folio *folio );

like, you hand it an inode and a folio, it hands you back an unsigned int. iconic signature behavior 💖

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💜 ARGUMENTS 💜

• inode — the inode which contains the blocks. she's the container, the mother figure 🫶
• folio — the folio. yes bestie, just the folio. that's the whole description. she's self-explanatory and she knows it ✨

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🧚 DESCRIPTION 🧚

if the block size is larger than the size of this folio, return zero. that's the rule. no blocks fit, so you get a big fat 0 😭

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🔥 CONTEXT 🔥

the caller should hold a refcount on the folio to prevent it from being split.

bestie please hold that refcount 🙈 if the folio gets split while you're looking at her, that's on you and it's giving undefined chaos. main character responsibility energy.

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👑 RETURN 👑

the number of filesystem blocks covered by this folio. that's the answer, that's the tea 🌈

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🌟 SEE ALSO 🌟

everything else living in the kernel's ./include/linux/pagemap.h file, and honestly? the whole friend group:

filemap_set_wb_err(9), filemap_check_wb_err(9), filemap_sample_wb_err(9), file_sample_sb_err(9), mapping_set_error(9), mapping_set_large_folios(9), mapping_align_index(9), mapping_pmd_folio_support(9), folio_flush_mapping(9), folio_inode(9), folio_attach_private(9), folio_change_private(9), folio_detach_private(9), fgf_t(9), fgf_set_order(9), write_begin_get_folio(9), filemap_get_folio(9), filemap_lock_folio(9), filemap_grab_folio(9), find_get_page(9), find_lock_page(9), find_or_create_page(9), grab_cache_page_nowait(9), folio_next_index(9), folio_next_pos(9), folio_file_page(9), folio_contains(9), page_pgoff(9), folio_pos(9), linear_page_delta(9), linear_page_index(9), linear_anon_page_index(9), folio_trylock(9), folio_lock(9), lock_page(9), folio_lock_killable(9), filemap_range_needs_writeback(9), struct readahead_control(9), page_cache_sync_readahead(9), page_cache_async_readahead(9), readahead_folio(9), readahead_pos(9), readahead_length(9), readahead_index(9), readahead_count(9), readahead_batch_length(9), folio_mkwrite_check_truncate(9)

like I said. the whole friend group. iykyk 💀

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and that's the page, bestie 🎀 this edition came out of ./include/linux and is dated October 2026 — so print it, frame it, put it on your wall. slay ✨💖🦋