generic_check_addressable(9)

💅 generic_check_addressable(9) — a Kernel API Manual moment

okay so bestie, welcome to generic_check_addressable(9), straight out of the Kernel API Manual. It's one tiny function, it's in ./fs/libfs.c, and it has exactly one job. Lowkey iconic of it tbh 🎀

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✨ NAME ✨

generic_check_addressable — the vibe check for whether your file system is actually addressable 🌸

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✨ SYNOPSIS ✨

int generic_check_addressable (unsigned blocksize_bits , u64 num_blocks );

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✨ ARGUMENTS ✨

• blocksize_bits — bestie this is the log of your file system block size. Not the block size itself, the log of it. Read the room 😭
• num_blocks — the number of blocks in your file system, typed as u64 because we're being fancy 💅

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✨ DESCRIPTION ✨

So here's the tea 🍵 — this function figures out whether a file system with num_blocks blocks (and a block size of 2**blocksize_bits, yes, that's the whole reason the argument is a log 😌) can actually be addressed by the system's sector_t and page cache.

Return value stays in its lane:

• 0 if it's all good, it's addressable, slay 🎉
• -EFBIG otherwise, i.e. too big, no cap 💀

That's genuinely it. Small function, big "am I going to fit in memory" energy 👑

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✨ SEE ALSO ✨

All the neighbours from the Kernel file ./fs/libfs.c — a whole group chat of (9) pages, fr fr 🫶

• simple_offset_init(9)
• simple_offset_add(9)
• simple_offset_remove(9)
• simple_offset_rename(9)
• simple_offset_rename_exchange(9)
• simple_offset_destroy(9)
• offset_dir_llseek(9)
• offset_readdir(9)
• simple_rename_timestamp(9)
• simple_setattr(9)
• simple_write_end(9)
• simple_read_from_buffer(9)
• simple_write_to_buffer(9)
• memory_read_from_buffer(9)
• generic_encode_ino32_fh(9)
• generic_fh_to_dentry(9)
• generic_fh_to_parent(9)
• simple_fsync_noflush(9)
• simple_fsync(9)
• simple_get_link(9)
• generic_ci_d_compare(9)
• generic_ci_d_hash(9)
• generic_ci_match(9)
• generic_set_sb_d_ops(9)
• inode_maybe_inc_iversion(9)
• inode_query_iversion(9)
• simple_inode_init_ts(9)
• path_from_stashed(9)
• simple_start_creating(9)

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ngl, go read them all if you want the full libfs lore 🌈

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okay that's the whole page, mwah 💖 this one came from the source ./fs, dated October 2026, and it's the generic_check_addressable(9) manual page — periodt. 🦋