__bh_read(9)

💜 __bh_read(9) — the Kernel API Manual glow-up 🎀

okay so bestie, we're in the Kernel API Manual today and the main character is __bh_read(9) — literally the function that submits a read for a locked buffer. yes queen, locked. don't come for me, that's what it says 💅

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✨ NAME ✨

__bh_read — Submit read for a locked buffer 🦋

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✨ SYNOPSIS ✨

int __bh_read (struct buffer_head *bh , blk_opf_t op_flags , bool wait
);

like, that's the whole vibe. three args, one int coming back at you 🌸

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✨ ARGUMENTS ✨

• bh — a struct buffer_head 🫶 that's it, that's the arg, it's your buffer head bestie
• op_flags — appending REQ_OP_* flags besides REQ_OP_READ ✨ (read is already the whole point, don't re-add it, iykyk)
• wait — bool, and it means wait until reading finish 💀 yes. that's the description. we love a terse king 👑

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✨ DESCRIPTION ✨

so what does it return, you ask? 🧚 it returns zero on success or if you don't wait — and -EIO on error 😭 literally the whole spec. no cap, that's it.

lowkey important: zero means "success or don't wait", so don't go reading tea leaves into that zero, bestie 🙈

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✨ SEE ALSO ✨

Kernel file ./fs/buffer.c and its 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), try_to_free_buffers(9), bh_uptodate_or_lock(9), __bh_read_batch(9) — the whole squad, no one left behind 👑🔥

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and that's the page, bestie!! 💖 sourced straight from ./fs, dated October 2026, and yeah we're citing __bh_read(9) one more time on the way out because the footer said so ⭐ slay 🌈