On Thu, Mar 31, 2022 at 03:05:33PM -0400, Vivek Goyal wrote: > On Thu, Mar 31, 2022 at 01:22:58PM +0200, Christian Brauner wrote: > > Hi Christian, > > Following the example in here. > > https://gitlab.com/brauner/fs.idmapped.overlay.xfstests.output/-/blob/main/manual.test.instructions > > sudo mount-idmapped --map-mount b:10000000:0:100000000000 ./my-tmp /mnt > > Initially I could not even create idmapped mounts. I had to specify > full path and then it works. But relative path (./my-tmp) does not > work. > > For example this works. > > /root/git/xfstests-dev/src/idmapped-mounts/mount-idmapped --map-mount b:10000000:0:100000000000 /root/idmapped-testing/my-tmp /root/idmapped-testing/shifted > > But this fails. > > $ /root/git/xfstests-dev/src/idmapped-mounts/mount-idmapped --map-mount b:10000000:0:100000000000 ./my-tmp shifted > > Bad file descriptor - Failed to open ./my-tmp > > Not sure if this is a limitation of idmapped-mounts or this is expected. Heh, this is certainly not a limitation of idmapped mounts. :D It is a limitation of the test binary. Specifically, if you care it does: source = new_argv[0]; target = new_argv[1]; fd_tree = sys_open_tree(-EBADF, source, OPEN_TREE_CLONE | OPEN_TREE_CLOEXEC | AT_EMPTY_PATH | (recursive ? AT_RECURSIVE : 0)); if you specify ./my-tmp then you get: open_tree(-9, "./my-dir", OPEN_TREE_CLONE|OPEN_TREE_CLOEXEC|AT_EMPTY_PATH) = -1 EBADF (Bad file descriptor) which means ./my-dir is taken relative to -9 which lands you in static const char *path_init(struct nameidata *nd, unsigned flags) [...] struct fd f = fdget_raw(nd->dfd); struct dentry *dentry; if (!f.file) return ERR_PTR(-EBADF); [...] For this to work we'd need to detect a relative path and pass AT_FDCWD. But that tool was really just intended for xfstests so I was lazy enough to force people to specify full paths.
