ext4_trim_all_free(9)

💅 ext4_trim_all_free(9) — like, the whole manual, but make it make sense

Okay bestie, so this is a page out of the Kernel API Manual (that's the manual name, mmkay, putting it right here so we don't lose it ✨). And the function? It's ext4_trim_all_free — literally the function that trims all the free space in an allocation group. That's what the name says. The name ate. 👑

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✨ NAME ✨

ext4_trim_all_free — function to trim all free space in alloc. group 🎀

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🦋 SYNOPSIS 🦋

ext4_grpblk_t ext4_trim_all_free (struct super_block *sb , ext4_group_t
group , ext4_grpblk_t start , ext4_grpblk_t max , ext4_grpblk_t
minblocks );

Yeah it's a whole signature. Five args. We're gonna go through every single one, don't worry. 💖

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🌸 ARGUMENTS 🌸

• sb — the super block for the file system. The main character of the whole fs, honestly. 👑
• group — the group that's getting trimmed. This is the one getting the glow-up. ✨
• start — the first group block to examine. Where we start looking, bestie. 🔍
• max — the last group block to examine. Where we stop. No going past this. 🛑
• minblocks — the minimum extent block count. Like, an extent has to be at least this big to count. 📏

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💀 DESCRIPTION 💀

Okay so here's the vibe: ext4_trim_all_free walks through the group's block bitmap, searching for free extents. That's the whole job. It's a hunter, and free extents are the prey. 🏹

When it finds a free extent? It marks it as used in the group buddy bitmap. Then it issues a TRIM command on this extent, and then frees the extent in the group buddy bitmap. So it's like: found it → flag it → TRIM it → let it go. 🦋 It's giving "borrowed, not owned." The way that it marks the extent used before trimming and then frees it right back — that's the whole little dance. Periodt. 💅

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🔥 SEE ALSO 🔥

Kernel file ./fs/ext4/mballoc.c — go read the source, iykyk:

• ext4_mb_clear_bb(9)
• ext4_free_blocks(9)
• ext4_group_add_blocks(9)
• ext4_trim_extent(9)
• ext4_trim_fs(9)

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And that's the whole page, bestie!! 🫶 This little gem lives in ./fs/ext4, it's dated October 2026, and it's filed under ext4_trim_all_free(9) in the Kernel API Manual. Go trim something. 🌈✨