From f7d3daca7c79d9b77e61f50f718b257b71d07498 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Wed, 21 Jun 2017 15:28:34 +0300 Subject: [PATCH] ovl: relax same fs constrain for ovl_check_origin() For the case of all layers not on the same fs, try to decode the copy up origin file handle on any of the lower layers. Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi --- fs/overlayfs/namei.c | 42 ++++++++++++++++++++++++------------------ 1 file changed, 24 insertions(+), 18 deletions(-) diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c index 277a55c8299a..6485beddaa1f 100644 --- a/fs/overlayfs/namei.c +++ b/fs/overlayfs/namei.c @@ -272,28 +272,24 @@ static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d, static int ovl_check_origin(struct dentry *dentry, struct dentry *upperdentry, struct path **stackp, unsigned int *ctrp) { - struct super_block *same_sb = ovl_same_sb(dentry->d_sb); struct ovl_entry *roe = dentry->d_sb->s_root->d_fsdata; struct vfsmount *mnt; - struct dentry *origin; + struct dentry *origin = NULL; + int i; - if (!same_sb || !roe->numlower) - return 0; - /* - * Since all layers are on the same fs, we use the first layer for - * decoding the file handle. We may get a disconnected dentry, - * which is fine, because we only need to hold the origin inode in - * cache and use its inode number. We may even get a connected dentry, - * that is not under the first layer's root. That is also fine for - * using it's inode number - it's the same as if we held a reference - * to a dentry in first layer that was moved under us. - */ - mnt = roe->lowerstack[0].mnt; - - origin = ovl_get_origin(upperdentry, mnt); - if (IS_ERR_OR_NULL(origin)) - return PTR_ERR(origin); + for (i = 0; i < roe->numlower; i++) { + mnt = roe->lowerstack[i].mnt; + origin = ovl_get_origin(upperdentry, mnt); + if (IS_ERR(origin)) + return PTR_ERR(origin); + + if (origin) + break; + } + + if (!origin) + return 0; BUG_ON(*stackp || *ctrp); *stackp = kmalloc(sizeof(struct path), GFP_TEMPORARY); @@ -371,6 +367,16 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, } if (upperdentry && !d.is_dir) { BUG_ON(!d.stop || d.redirect); + /* + * Lookup copy up origin by decoding origin file handle. + * We may get a disconnected dentry, which is fine, + * because we only need to hold the origin inode in + * cache and use its inode number. We may even get a + * connected dentry, that is not under any of the lower + * layers root. That is also fine for using it's inode + * number - it's the same as if we held a reference + * to a dentry in lower layer that was moved under us. + */ err = ovl_check_origin(dentry, upperdentry, &stack, &ctr); if (err) -- 2.20.1