unlocked_inode_to_wb_begin(9)

💫 unlocked_inode_to_wb_begin(9) 💫

okay bestie, so this one lives in the Kernel API Manual and it's literally the glow-up your inode's writeback access needed. let's get into it 🎀

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✨ NAME ✨

unlocked_inode_to_wb_begin — begin an unlocked inode wb access transaction. yes queen, unlocked, we're being brave today 💅

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✨ SYNOPSIS ✨

struct bdi_writeback * unlocked_inode_to_wb_begin (struct inode *inode ,
struct wb_lock_cookie *cookie );

like, that's the whole vibe. returns a struct bdi_writeback * and takes two args. slay.

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✨ ARGUMENTS ✨

• inode — the target inode 🎯 like, the actual star of the show
• cookie — an output param, and no you cannot snack on it 🍪 it's gotta get passed straight into the end function later, that's its whole purpose

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✨ DESCRIPTION ✨

so here's the situation, bestie. the caller wants to access the wb associated with inode, but is not holding inode->i_lock, the i_pages lock, or wb->list_lock. none of them. zero locks held. living dangerously, honestly 💀

this function's whole job is to figure out which wb belongs to that inode and then make sure the association doesn't change until the transaction is finished with unlocked_inode_to_wb_end. like it's holding the relationship together so nobody switches up mid-transaction. main character energy fr fr 👑

💖 important, don't skip this: the caller must call unlocked_inode_to_wb_end with *cookie afterwards, and can't sleep during the transaction. also, IRQs may or may not be disabled on return — yes, "may or may not", that's not me being vague, that's the actual deal, so plan accordingly 🙈

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✨ SEE ALSO ✨

• Kernel file ./include/linux/backing-dev.h
• writeback_in_progress(9)
• inode_cgwb_enabled(9)
• wb_find_current(9)
• wb_get_create_current(9)
• inode_to_wb(9)
• unlocked_inode_to_wb_end(9) — the other half of this duo, you literally cannot skip it 🫶

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and that's the page, bestie!! this little icon comes to you from ./include/linux, dated October 2026, and it's filed under unlocked_inode_to_wb_begin(9) — go forth and lock responsibly 🌸🦋💜