ubifs_prepare_node_hmac(9)

💅 ubifs_prepare_node_hmac(9) — the kernel API manual, but make it make sense

okay so bestie, welcome to the Kernel API Manual entry for ubifs_prepare_node_hmac — yes that's a mouthful, yes it's iconic, and yes we're gonna get through it together 🫶

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✨ NAME ✨

ubifs_prepare_node_hmac — literally the function that preps a node so it's ready to be written to flash 💾✨

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✨ SYNOPSIS ✨

int ubifs_prepare_node_hmac (struct ubifs_info *c , void *node , int len
, int hmac_offs , int pad );

that's the whole vibe check right there, no cap 🔥

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✨ ARGUMENTS ✨

• c — the UBIFS file-system description object, aka the main character of this whole file system 🌈
• node — the node that needs padding, our little glow-up victim 💅
• len — the length of the node, keep it exact bestie 📏
• hmac_offs — the offset of the HMAC inside the node, iykyk 🔐
• pad — tells us whether the buffer has to be padded or not 🎀

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✨ DESCRIPTION ✨

so here's the tea ☕ — this function takes the node sitting at node and gets it fully ready to be written to the media. it does the whole routine:

• it calculates the node CRC ✅
• it fills in the common header 📝
• and it adds proper padding up to the next minimum I/O unit — but only if pad is not zero, okay? don't forget that condition 🙈

and one more thing: if hmac_offs is positive, then a HMAC gets inserted into the node at the given offset 🔐✨

as for what it gives back — this function returns 0 for success, or a negative error code otherwise. so zero means slay, negative means something went off 😭

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✨ SEE ALSO ✨

the kernel file ./fs/ubifs/io.c and honestly the whole friend group 👑

• ubifs_ro_mode(9)
• ubifs_check_node(9)
• ubifs_pad(9)
• next_sqnum(9)
• ubifs_prepare_node(9)
• ubifs_prep_grp_node(9)
• wbuf_timer_callback_nolock(9)
• new_wbuf_timer_nolock(9)
• cancel_wbuf_timer_nolock(9)
• ubifs_wbuf_sync_nolock(9)
• ubifs_wbuf_seek_nolock(9)
• ubifs_bg_wbufs_sync(9)
• ubifs_wbuf_write_nolock(9)
• ubifs_write_node_hmac(9)
• ubifs_write_node(9)
• ubifs_read_node_wbuf(9)
• ubifs_read_node(9)
• ubifs_wbuf_init(9)
• ubifs_wbuf_add_ino_nolock(9)
• wbuf_has_ino(9)
• ubifs_sync_wbufs_by_inode(9)

like, that's the whole squad, go read them too 🦋

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ngl bestie, if you're touching flash nodes in UBIFS you already have main character energy. go off 👑

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and that's a wrap! this page came to you from ./fs/ubifs, dated October 2026 — mwah, bye bestie 💖🎀🌷