sd_zbc_check_capacity(9)

💖 sd_zbc_check_capacity(9) 💖

okay so bestie, welcome to the Kernel API Manual — this one's a little function from the SCSI disk zoned-block-command world, and yeah, the name is a mouthful, but we're gonna get through it together 🫶

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✨ NAME ✨

sd_zbc_check_capacity — check the device capacity 💅

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🎀 SYNOPSIS 🎀

int sd_zbc_check_capacity (struct scsi_disk *sdkp , unsigned char *buf ,
u32 *zblocks );

like, yes, it takes three args and returns an int, iconic behavior honestly 👑

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🦋 ARGUMENTS 🦋

• sdkp — the target disk, our main character 🌟
• buf — the command buffer, just vibing in there
• zblocks — zone size in logical blocks, noted 📝

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🌸 DESCRIPTION 🌸

so what does it do, you ask? it gets the device zone size, and then it checks that the device capacity — the one reported by READ CAPACITY — matches the max_lba value plus one of the report zones command reply, but only for devices with RC_BASIS == 0. not me being specific about the RC_BASIS == 0 condition, that's literally the whole point 😭

and then, the moment of truth: it returns 0 upon success, or an error code upon failure. slay if it's zero, sad girl hours if it's not 💀

ngl, if the capacity doesn't line up, that's your error code right there — no cap.

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🧚 SEE ALSO 🧚

the kernel file ./drivers/scsi/sd_zbc.c plus the whole friend group:

• sd_zbc_parse_report(9)
• sd_zbc_do_report_zones(9)
• sd_zbc_alloc_report_buffer(9)
• sd_zbc_zone_sectors(9)
• sd_zbc_report_zones(9)
• sd_zbc_setup_zone_mgmt_cmnd(9)
• sd_zbc_complete(9)
• sd_zbc_check_zoned_characteristics(9)
• sd_zbc_read_zones(9)

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and that's the whole page, bestie!! 🎀 this one lives in ./drivers/scsi, dated October 2026, and goes by sd_zbc_check_capacity(9) — mwah, go read the source, ily, bye 💖✨