[PATCH v3 09/16] ovl: lookup non-dir inode copy up origin

Amir Goldstein
2017-04-26T21:35:30Z

When non directory upper has overlay.origin.fh xattr, lookup in lower
layers by file handle or by path to find the copy up origin inode.

Until this change, a non-dir dentry could have had oe->numlower == 1
with oe->lowerstack[0] pointing at the copy up origin path, right
after copy up, but not when a non-dir dentry was created by ovl_lookup().

After this change, a non-dir dentry could be pointing at the copy up
origin after ovl_lookup(), as long as the copy up was done by overlayfs
that had redirect_fh support.

Non-dir entries that were copied up by overlayfs without redirect_fh
support will look the same as pure upper non-dir entries.

This is going to be used for persistent inode numbers across copy up.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
fs/overlayfs/namei.c | 31 ++++++++++++++++++-------------
1 file changed, 18 insertions(+), 13 deletions(-)

diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index 970d8158..ad2c784 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -188,15 +188,16 @@ static int ovl_lookup_data(struct dentry *this, struct ovl_lookup_data *d,
goto put_and_out;
}
if (!d_can_lookup(this)) {
- d->stop = true;
- if (d->is_dir)
+ if (d->is_dir) {
+ d->stop = true;
goto put_and_out;
- goto out;
- }
- d->is_dir = true;
- if (!d->last && ovl_is_opaquedir(this)) {
- d->stop = d->opaque = true;
- goto out;
+ }
+ } else {
+ d->is_dir = true;
+ if (!d->last && ovl_is_opaquedir(this)) {
+ d->stop = d->opaque = true;
+ goto out;
+ }
}
if (d->by_path) {
err = ovl_check_redirect(this, d, prelen, post);
@@ -208,6 +209,9 @@ static int ovl_lookup_data(struct dentry *this, struct ovl_lookup_data *d,
if (err)
goto out_err;
}
+ /* No redirect for non-dir means pure upper */
+ if (!d->is_dir)
+ d->stop = !d->fh && !d->redirect;
out:
*ret = this;
return 0;
@@ -456,11 +460,11 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
}

/*
- * For now we only support lower by fh in single layer, because
- * fallback from lookup by fh to lookup by path in mid layers for
- * merge directory is not yet implemented.
+ * For now we only support lookup by fh in single layer for directory,
+ * because fallback from lookup by fh to lookup by path in mid layers
+ * for merge directory is not yet implemented.
*/
- if (!ofs->redirect_fh || ofs->numlower > 1)
+ if (!ofs->redirect_fh || (d.is_dir && ofs->numlower > 1))
ovl_reset_redirect_fh(&d);

if (!d.stop && (poe->numlower || d.fh)) {
@@ -520,7 +524,8 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
stack[ctr].mnt = lowerpath.mnt;
ctr++;

- if (d.stop)
+ /* Do not follow non-dir copy up origin more than once */
+ if (d.stop || !d.is_dir)
break;

if (d.redirect && d.redirect[0] == '/' && poe != roe) {
--
2.7.4