ext4_get_group_desc(9)

✨ ext4_get_group_desc(9) ✨

okay so bestie, welcome to the Kernel API Manual 💖 this one's a kernel-API page, section 9, and it's all about grabbing a group descriptor off the disk. it's giving "short but mighty" and honestly? iconic.

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🎀 NAME 🎀

ext4_get_group_desc — load group descriptor from disk

like literally, that's the whole job. load. group descriptor. from. disk. periodt. 💅

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🦋 SYNOPSIS 🦋

struct ext4_group_desc * ext4_get_group_desc (struct super_block *sb ,
ext4_group_t block_group , struct buffer_head **bh );

not me dropping the full signature so you can copy it exactly 🫶 — it returns a struct ext4_group_desc *, and it takes three things. let's get into them 👇

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🌸 ARGUMENTS 🌸

• sb — the super block 💫 yeah, that one. your super block.
• block_group — the given block group. that's the group you're asking about, no cap.
• bh — pointer to the buffer head to store the block group descriptor 👑 so it's a pointer-to-a-pointer situation, and that's where the descriptor's buffer head ends up living.

ngl, bh is the sneaky one — it's a struct buffer_head **, so you're handing over the address of your pointer. do not hand it a plain pointer, bestie, i'm begging 😭

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🌈 SEE ALSO 🌈

this is the friend group of related functions, and they all ate fr fr 🔥

Kernel file ./fs/ext4/balloc.c — that's the home base for this one, go say hi 💜

• ext4_read_block_bitmap_nowait(9)
• ext4_has_free_clusters(9)
• ext4_should_retry_alloc(9)
• ext4_count_free_clusters(9)
• ext4_bg_has_super(9)
• ext4_bg_num_gdb(9)
• ext4_inode_to_goal_block(9)

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and that's the whole page!! short, sweet, and extremely useful 💖 iykyk.

so yeah — this whole thing lives under ./fs/ext4, and it's dated October 2026, version vibe and all, with ext4_get_group_desc(9) stamped right on the footer like a lil signature 🎀 mwah, go read a group descriptor, main character 🧚‍♀️✨