__blkdev_issue_zeroout(9)

💖 __blkdev_issue_zeroout(9) 💖

okay bestie, welcome to the Kernel API Manual ✨ — this is the page for __blkdev_issue_zeroout, and yes it's a double-underscore icon, we respect her 💅

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🌸 NAME 🌸

__blkdev_issue_zeroout — generate number of zero filled write bios 🎀 like, it makes a whole bunch of zero-write bios for you, no cap

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✨ SYNOPSIS ✨

int __blkdev_issue_zeroout (struct block_device *bdev , sector_t sector
, sector_t nr_sects , gfp_t gfp_mask , struct bio **biop , unsigned
flags );

that's the whole signature, copied exactly, don't @ me 🫶

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🦋 ARGUMENTS 🦋

• bdev — the blockdev to issue 💫 it's a struct block_device *, she's the main character here
• sector — start sector 🌸 where the zeroing begins, bestie
• nr_sects — number of sectors to write ⭐ count 'em
• gfp_mask — memory allocation flags (for bio_alloc) 💜 iykyk
• biop — pointer to anchor bio 🎀 it's a struct bio **, so, a pointer to a pointer, stay with me
• flags — controls detailed behavior 🔥 the little switches that change the vibe check

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👑 DESCRIPTION 👑

so what does she actually do? Zero-fill a block range, either using hardware offload or by explicitly writing zeroes to the device. literally both paths lead to zeroes, she just picks how 💅

now, the caveats — pay attention, this is the important part 🙈

• If a device is using logical block provisioning, the underlying space will not be released if flags contains BLKDEV_ZERO_NOUNMAP. so like, the space stays taken, fr fr
• If flags contains BLKDEV_ZERO_NOFALLBACK, the function will return -EOPNOTSUPP if no explicit hardware offload for zeroing is provided. so if there's no offload, she just ✨ gives up ✨ and hands you back -EOPNOTSUPP

bestie pls note: those two flags are the whole personality of this function, don't mix them up 🫶

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🌈 SEE ALSO 🌈

• Kernel file ./block/blk-lib.c 🍓 that's where the source lives, go look
• blkdev_issue_discard(9)
• blkdev_issue_zeroout(9)

all three, listed, exactly, periodt 💅

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and that's the page!! 🧚 mwah 💖

sign-off: this whole thing came from ./block, dated October 2026 — Kernel API Manual energy only. stay slay, stay zeroed ✨👑