On Thu, Mar 17, 2016 at 10:02:00AM +0100, Miklos Szeredi wrote: > Add a new helper, file_dentry() [*], to get the filesystem's own dentry > from the file. This simply compares file_inode(file->f_path.dentry) to > file_inode(file) and if they are equal returns file->f_path.dentry (this is > the common, non-overlayfs case). > > In the uncommon case (regular file on overlayfs) it will call into > overlayfs's ->d_native_dentry() to get the underlying dentry matching > file_inode(file). What's wrong with making ovl_dentry_real() an instance of optional ->d_real() method and having a flag (DCACHE_OP_REAL) controlling its calls? With d_real(dentry) returning either that or dentry itself, and file_dentry(file) being simply d_real(file->f_path.dentry)... Why do we need to look at the inode at all? d_set_d_op() dereferences ->d_op anyway, as well as setting ->d_flags, so there's no extra cost there, and "test bit in ->d_flags + branch not taken" is all it would cost in normal case... -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html