truncate_data_node(9)

✨ truncate_data_node — the Kernel API Manual glow-up ✨

okay bestie, so this page is from the Kernel API Manual and it's all about truncate_data_node, which is lowkey serving a very specific and important job. lemme break it down for you 🫶

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🌸 NAME 🌸

truncate_data_node — re-compress/encrypt a truncated data node. that's it. that's the whole vibe. it's giving "glow-up for a data node that just got cut short." 💅

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✨ SYNOPSIS ✨

int truncate_data_node (const struct ubifs_info *c , const struct inode *inode , unsigned int block , struct ubifs_data_node *dn , int *new_len , int dn_size );

like, yeah. that's the whole signature. no cap. 🎀

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🦋 ARGUMENTS 🦋

okay so here's the cast of characters, and you know we're not skipping a single one:

• c — the UBIFS file-system description object. the main character, honestly. it's the ✨context✨ for everything.
• inode — the inode which refers to the data node. like, the inode is the one holding hands with this data node, iykyk. 🔥
• block — the data block number. it's giving "which block are we even talking about bestie." 📍
• dn — the data node to re-compress. here's our star!! the whole reason we're here. 🌟
• new_len — new length. she's new, she's improved, she's gotten shorter. 💅
• dn_size — size of the data node dn in memory. (in memory specifically!! don't get it twisted 🫶)

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💖 DESCRIPTION 💖

so here's the tea ☕: this function is used when an inode is truncated and the last data node of the inode has to be re-compressed/encrypted and re-written. that's literally it. when the last node gets caught in the truncation crossfire, this function swoops in, re-compresses/encrypts it, and gets it written back out. iconic behavior, honestly. ✨

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🌈 SEE ALSO 🌈

okay so this one's a long list bestie — all of these live in the kernel file ./fs/ubifs/journal.c, and yes I'm listing every single one because we don't skip the boring parts on this account. periodt. 👑

• zero_ino_node_unused(9)
• zero_dent_node_unused(9)
• zero_trun_node_unused(9)
• reserve_space(9)
• write_head(9)
• __queue_and_wait(9)
• wait_for_reservation(9)
• wake_up_reservation(9)
• add_or_start_queue(9)
• make_reservation(9)
• release_head(9)
• finish_reservation(9)
• get_dent_type(9)
• pack_inode(9)
• mark_inode_clean(9)
• ubifs_jnl_update(9)
• ubifs_jnl_write_data(9)
• ubifs_jnl_write_inode(9)
• ubifs_jnl_delete_inode(9)
• ubifs_jnl_xrename(9)
• ubifs_jnl_rename(9)
• ubifs_jnl_truncate(9)
• ubifs_jnl_delete_xattr(9)
• ubifs_jnl_change_xattr(9)

that's 24 besties. 24 of them. and they all came from ./fs/ubifs/journal.c. no cap. 🔥

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and that's the whole page!! tysm for reading bestie, this has been truncate_data_node(9) from ./fs/ubifs, dated October 2026, and she ate. 💅✨