mode_strip_umask(9)

🌸 mode_strip_umask(9) — a Kernel API Manual moment 🌸

okay bestie, buckle up, we're in the Kernel API Manual today and this one is genuinely iconic. it's mode_strip_umask, and no cap, it's the little helper that decides where your umask gets stripped. main character energy fr fr 💅

---

✨ NAME ✨

mode_strip_umask — the girl who handles vfs umask stripping, periodt 🎀

---

🦋 SYNOPSIS 🦋

umode_t mode_strip_umask (const struct inode *dir , umode_t mode );

literally just look at her. two arguments, one umode_t return, zero drama ✨

---

🍓 ARGUMENTS 🍓

• dir — the parent directory of the new inode. like, where the new baby inode is gonna live 🏠
• mode — the mode of the new inode that's about to be created inside dir. this is the vibe we're working with 💜

---

🌈 DESCRIPTION 🌈

okay so here's the tea 🍵 — in most filesystems, whether umask stripping happens here or somewhere else depends on one thing: does the filesystem support POSIX ACLs or not?

• if the filesystem doesn't support POSIX ACLs → the umask stripping is done directly in here. right here. this function. she ate 💅
• if the filesystem does support POSIX ACLs → the umask stripping gets deferred, postponed, pushed back, until the filesystem calls posix_acl_create. she's a busy girl, she'll get to it later 🫶

and then there's the third group, the ✨special✨ ones. some filesystems (hi, NFSv4 👋) also want to avoid umask stripping by the VFS — but they don't support POSIX ACLs. awkward, right? 😭 good news: those filesystems can set SB_I_NOUMASK to get that exact effect without declaring that they support POSIX ACLs. loophole queen behavior, honestly 👑

---

⭐ RETURN ⭐

returns mode — that's it, that's the return. short and sweet, ngl 🌸

---

🧚 SEE ALSO 🧚

• Kernel file ./include/linux/namei.h
• end_removing(9)
• retry_estale(9)

go read those too, iykyk 💖

---

🎀 little reminder bestie: the POSIX ACL support question is the whole plot here, so don't skip it, fr fr. and SB_I_NOUMASK is the move for the NFSv4 girlies who want VFS to leave their umask alone 🙈

---

and that's the whole page, you're so welcome 💜 this lil masterpiece lives in ./include/linux, dated October 2026, and it's filed under mode_strip_umask(9) — go forth and strip those umasks responsibly, bestie 🦋✨👑