On Thu, Feb 06, 2025 at 04:42:38PM +1100, NeilBrown wrote: > vfs_mkdir() does not guarantee to make the child dentry positive on > success. It may leave it negative and then the caller needs to perform a > lookup to find the target dentry. > > This patch introduced vfs_mkdir_return() which performs the lookup if > needed so that this code is centralised. > > This prepares for a new inode operation which will perform mkdir and > returns the correct dentry. * Calling conventions stink; make it _consume_ dentry reference and return dentry reference or ERR_PTR(). Callers will be happier that way (check it). * Calling conventions should be documented in commit message *and* in D/f/porting * devpts, nfs4recover and xfs might as well convert (not going to hit the "need a lookup" case anyway) * that + /* Need a "const" pointer. We know d_name is const + * because we hold an exclusive lock on i_rwsem + * in d_parent. + */ + const struct qstr *d_name = (void*)&dentry->d_name; + d = lookup_dcache(d_name, dentry->d_parent, 0); + if (!d) + d = __lookup_slow(d_name, dentry->d_parent, 0); doesn't need a cast. C is perfectly fine with T *x = foo(); const T *y = x; You are not allowed to _strip_ qualifiers; adding them is fine. Same reason why you are allowed to pass char * to strlen() without any casts whatsoever. Comment re stability is fine; the cast is pure WTF material.
