try_to_free_buffers(9)

💅 try_to_free_buffers — a Kernel API Manual moment ✨

okay so bestie, welcome to the try_to_free_buffers(9) page, aka the kernel API manual entry you didn't know you needed but now literally cannot live without 🫶

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🌸 NAME 🌸

try_to_free_buffers — release buffers attached to this folio. that's it. that's the whole vibe. 🎀

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✨ SYNOPSIS ✨

bool try_to_free_buffers (struct folio *folio );

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🦋 ARGUMENTS 🦋

• folio — the folio. yes, that's genuinely all it says. it's giving "I have one job and I'm doing it." 👑

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💖 DESCRIPTION 💖

so here's the tea ☕ — if any buffers are in use (dirty, under writeback, elevated refcount), no buffers will be freed. like, none. zero. the whole thing just nopes out 🙈

and here's where it gets a little spicy 🌶️ — if the folio is dirty but all the buffers are clean, then we need to be sure to mark the folio clean as well. why?? because the folio may be against a block device, and a later reattachment of buffers to a dirty folio will set all buffers dirty. which would corrupt filesystem data on the same device. 😭 so yeah, that's a real "do not skip this step" situation, no cap.

the same applies to regular filesystem folios: if all the buffers are clean then we set the folio clean and proceed. slay. 💅 but to do that, we require total exclusion from block_dirty_folio. that is obtained with i_private_lock. total exclusion, bestie — we're not doing "mostly excluded," we're doing the whole thing 🔥

and if you want exclusion against try_to_free_buffers, you can get it by either locking the folio or by holding its mapping's i_private_lock. pick your fighter, both are valid 🧚

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🌈 CONTEXT 🌈

process context. folio must be locked. will not sleep. 😴🚫

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⭐ RETURN ⭐

true if all buffers attached to this folio were freed. otherwise, well… not true, bestie 💀

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👑 SEE ALSO 👑

kernel file ./fs/buffer.c, plus the whole friend group:

• bio_endio_bh(9)
• end_buffer_read_sync(9)
• bh_end_read(9)
• bh_end_write(9)
• bh_end_async_write(9)
• mmb_sync(9)
• block_dirty_folio(9)
• mark_buffer_dirty(9)
• __brelse(9)
• __bforget(9)
• bh_submit(9)
• bdev_getblk(9)
• __bread_gfp(9)
• block_invalidate_folio(9)
• clean_bdev_aliases(9)
• bh_uptodate_or_lock(9)
• __bh_read(9)
• __bh_read_batch(9)

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and that's the page, babes 🍓 this little icon lives in ./fs and it's stamped October 2026 — so go forth, free those buffers, and remember: lock the folio first 💜✨