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There are two filename-related problems in io_uring and its interplay with audit. Filenames are imported when request is submitted and used when it is processed. Unfortunately, the latter may very well happen in a different thread. In that case the reference to filename is put into the wrong audit_context - that of submitting thread, not the processing one. Audit logics is called by the latter, and it really wants to be able to find the names in audit_context current (== processing) thread. Another related problem is the headache with refcounts - normally all references to given struct filename are visible only to one thread (the one that uses that struct filename). io_uring violates that - an extra reference is stashed in audit_context of submitter. It gets dropped when submitter returns to userland, which can happen simultaneously with processing thread deciding to drop the reference it got. We paper over that by making refcount atomic, but that means pointless headache for everyone. Solution: the notion of partially imported filenames. Namely, already copied from userland, but *not* exposed to audit yet. io_uring can create that in submitter thread, and complete the import (obtaining the usual reference to struct filename) in processing thread. Object: struct delayed_filename. Primitives for working with it: delayed_getname(&delayed_filename, user_string) - copies the name from userland, returning 0 and stashing the address of (still incomplete) struct filename in delayed_filename on success and returning -E... on error. delayed_getname_uflags(&delayed_filename, user_string, atflags) - similar, in the same relation to delayed_getname() as getname_uflags() is to getname() complete_getname(&delayed_filename) - completes the import of filename stashed in delayed_filename and returns struct filename to caller, emptying delayed_filename. CLASS(filename_complete_delayed, name)(&delayed_filename) - variant of CLASS(filename) with complete_getname() for constructor. dismiss_delayed_filename(&delayed_filename) - destructor; drops whatever might be stashed in delayed_filename, emptying it. putname_to_delayed(&delayed_filename, name) - if name is shared, stashes its copy into delayed_filename and drops the reference to name, otherwise stashes the name itself in there. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>