Messages in this thread | | | Date | Fri, 25 Nov 2016 15:56:04 +0100 | From | Quentin Casasnovas <> | Subject | opening a file on a stacked overlayfs is broken. |
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Hi,
Stacking an overlayfs on top of an overlayfs doens't work when it used to (tested on v4.9-rc5):
#!/bin/bash -xeu tmpdir=$(mktemp -d) pushd ${tmpdir}
mkdir -p {upper,lower,work} echo 'foo' > lower/bar mount -t overlay level_zero upper -o lowerdir=lower,upperdir=upper,workdir=work cat upper/bar
tmpdir2=$(mktemp -d) pushd ${tmpdir2}
mkdir -p {upper,work} mount -t overlay level_one upper -o lowerdir=${tmpdir}/upper,upperdir=upper,workdir=work stat upper/bar # Works fine cat upper/bar # open() returns ENXIO
I _think_ (I haven't bisected it) the guilty commit is 2d902671ce1c ("vfs: merge .d_select_inode() into .d_real()"), where vfs_open() -> uses d_real() with a a NULL inode, which prevents any recursion from happening, when before d_select_inode() would do the right thing and recurse.
It should be noted this has already been broken and fixed in the past year in 1c8a47df36d7 ("ovl: fix open in stacked overlay").
Let me know if I can help, Q [unhandled content-type:application/pgp-signature] | |