folio_end_read(9)

💅 folio_end_read — the folio_end_read(9) page, bestie edition

okay so welcome to the folio_end_read(9) glow-up ✨ this one lives in the Kernel API Manual and honestly? she's short, she's sweet, she's important. let's get into it 🫶

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🌸 NAME 🌸

folio_end_read — literally just: end read on a folio. that's the whole vibe. periodt.

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✨ SYNOPSIS ✨

void folio_end_read (struct folio *folio , bool success );

like yes that's the entire signature, no cap 💅

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🎀 ARGUMENTS 🎀

• folio — The folio. that's her. that's the main character of this whole page 🌟
• success — true if all reads completed successfully. like, did everything actually work? yes or no, no in-between 🙈

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💖 DESCRIPTION 💖

so here's the tea ☕ when all reads against a folio have completed, filesystems should call this function to let the pagecache know that no more reads are outstanding. it's literally the "we're done here, bestie" signal 🫡

this will unlock the folio and wake up any thread sleeping on the lock. yeah, she wakes the whole group chat up 😭

and the folio will also be marked uptodate if all reads succeeded. slay. that's the reward for a job well done ✨👑

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🦋 CONTEXT 🦋

• may be called from interrupt or process context. both? both. flexible queen 💅
• may not be called from NMI context. nope. not there. do not do it 🚫💀

fr fr, respect the NMI restriction. it's not a vibe check you want to fail.

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👑 SEE ALSO 👑

Kernel file ./mm/filemap.c, and the whole squad:

• filemap_remove_folio(9)
• filemap_fdatawrite_range(9)
• filemap_flush_range(9)
• filemap_flush(9)
• filemap_range_has_page(9)
• filemap_fdatawait_range(9)
• filemap_fdatawait_range_keep_errors(9)
• file_fdatawait_range(9)
• filemap_fdatawait_keep_errors(9)
• filemap_write_and_wait_range(9)
• file_check_and_advance_wb_err(9)
• file_write_and_wait_range(9)
• replace_page_cache_folio(9)
• softleaf_entry_wait_on_locked(9)
• folio_put_wait_locked(9)
• folio_unlock(9)
• folio_end_private_2(9)
• folio_wait_private_2(9)
• folio_wait_private_2_killable(9)
• folio_end_writeback_no_dropbehind(9)
• folio_end_writeback(9)
• __folio_lock(9)
• page_cache_next_miss(9)
• page_cache_prev_miss(9)
• __filemap_get_folio_mpol(9)
• find_get_entries(9)
• find_lock_entries(9)
• filemap_get_folios(9)
• filemap_get_folios_contig(9)
• filemap_get_folios_tag(9)
• filemap_get_folios_dirty(9)
• filemap_read(9)
• generic_file_read_iter(9)
• filemap_splice_read(9)
• mapping_seek_hole_data(9)
• filemap_fault(9)
• read_cache_folio(9)
• mapping_read_folio_gfp(9)
• read_cache_page_gfp(9)
• __generic_file_write_iter(9)
• generic_file_write_iter(9)
• filemap_release_folio(9)
• filemap_invalidate_inode(9)
• filemap_cachestat(9)

iykyk 💜 that's the entire friend group, no one left out.

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and that's the page!! 💖 this little gem comes to you from the ./mm source, dated October 2026 — go forth and end those reads, bestie 🧚🌸⭐