On Tue, Mar 30, 2010 at 07:16:18AM -0400, Theodore Tso wrote: > Hmmm.... do we also need to worry about read-only fd's of directories, and interaction with the *at() system calls. For example: > > int renameat(int olddirfd, const char *oldpath, int newdirfd, const char *newpath) > > ... where olddirfd and newdirfd might be r/o file descriptors for directories participating in a Union mount? > > This is just one example, of course. There's also openat(), symlinkat(), etc. Directories are always copied up in this version of union mounts, so it doesn't matter whether you open a directory O_RDONLY or not, you'll always have the topmost version and see all the effects of link(), linkat(), rename(), renameat(), etc. It's only with files that you can get a stale copy if you open it O_RDONLY and it gets modified through some other path. Always copying up directories solves a lot of problems. I managed to eliminate several hundred lines of code with that change in the design. -VAL -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
