ceph_mdsc_build_path(9)

💖 ceph_mdsc_build_path(9) 💖

okay so this is a page from the Kernel API Manual — yes, the kernel, bestie, we're in the kernel now — and it's literally about building a path string to a given dentry. that's the whole vibe. ✨

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🎀 SYNOPSIS 🎀

char * ceph_mdsc_build_path (struct ceph_mds_client *mdsc , struct
dentry *dentry , struct ceph_path_info *path_info , int for_wire );

like, four args, returns a char *, we move 💅

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🌸 ARGUMENTS 🌸

• mdsc — the mds client, your main character struct 🫶
• dentry — the dentry we're building a path to, like the destination of the whole journey
• path_info — the output situation: path, length, base ino+snap, plus the freepath ownership flag (so you know who's responsible for freeing, very important, don't ghost your memory management 🫶)
• for_wire — is this path actually getting sent to the MDS? yes/no, that's it

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🦋 DESCRIPTION 🦋

So we're building a string that represents the path to the dentry. Honestly it's mostly called for two totally different purposes:

1. we need to build a path string to send to the MDS (for_wire == true)
2. we need a path string for local presentation (e.g. debugfs) (for_wire == false)

The path is built in reverse, starting with the dentry — iconic, backwards, we love her — and then we walk back up toward the root, building the path until the first non-snapped inode is reached (for_wire) or the root inode is reached (!for_wire).

Also, and this is the detail that eats: hidden .snap dirs get encoded as a double /. Like, literally:

foo/.snap/bar -> foo//bar

no cap, that's the encoding. 🔥

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⭐ SEE ALSO ⭐

• Kernel file ./fs/ceph/mds_client.c
• ceph_mdsc_wait_for_reset(9)

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and that's the whole page, bestie!! huge love to ./fs/ceph for putting it out, October 2026 edition, version vibes included 💜🎀💅