4.16-stable review patch. If anyone has any objections, please let me know.
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From: Amir Goldstein amir73il@gmail.com
commit 695b46e76b62447e506cddc87e088236498008e5 upstream.
Eddie Horng reported that readdir of an overlayfs directory that was exported via NFSv3 returns entries with d_type set to DT_UNKNOWN. The reason is that while preparing the response for readdirplus, nfsd checks inside encode_entryplus_baggage() that a child dentry's inode number matches the value of d_ino returns by overlayfs readdir iterator.
Because the overlayfs inodes use arbitrary inode numbers that are not correlated with the values of st_ino/d_ino, NFSv3 falls back to not encoding d_type. Although this is an allowed behavior, we can fix it for the case of all overlayfs layers on the same underlying filesystem.
When NFS export is enabled and d_ino is consistent with st_ino (samefs), set the same value also to i_ino in ovl_fill_inode() for all overlayfs inodes, nfsd readdirplus sanity checks will pass. ovl_fill_inode() may be called from ovl_new_inode(), before real inode was created with ino arg 0. In that case, i_ino will be updated to real upper inode i_ino on ovl_inode_init() or ovl_inode_update().
Reported-by: Eddie Horng eddiehorng.tw@gmail.com Tested-by: Eddie Horng eddiehorng.tw@gmail.com Signed-off-by: Amir Goldstein amir73il@gmail.com Fixes: 8383f1748829 ("ovl: wire up NFS export operations") Cc: stable@vger.kernel.org #v4.16 Signed-off-by: Miklos Szeredi mszeredi@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/overlayfs/inode.c | 21 +++++++++++++++++---- fs/overlayfs/util.c | 8 +++++++- 2 files changed, 24 insertions(+), 5 deletions(-)
--- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -459,9 +459,20 @@ static inline void ovl_lockdep_annotate_ #endif }
-static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev) +static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev, + unsigned long ino) { - inode->i_ino = get_next_ino(); + /* + * When NFS export is enabled and d_ino is consistent with st_ino + * (samefs), set the same value to i_ino, because nfsd readdirplus + * compares d_ino values to i_ino values of child entries. When called + * from ovl_new_inode(), ino arg is 0, so i_ino will be updated to real + * upper inode i_ino on ovl_inode_init() or ovl_inode_update(). + */ + if (inode->i_sb->s_export_op && ovl_same_sb(inode->i_sb)) + inode->i_ino = ino; + else + inode->i_ino = get_next_ino(); inode->i_mode = mode; inode->i_flags |= S_NOCMTIME; #ifdef CONFIG_FS_POSIX_ACL @@ -597,7 +608,7 @@ struct inode *ovl_new_inode(struct super
inode = new_inode(sb); if (inode) - ovl_fill_inode(inode, mode, rdev); + ovl_fill_inode(inode, mode, rdev, 0);
return inode; } @@ -710,6 +721,7 @@ struct inode *ovl_get_inode(struct super struct inode *inode; bool bylower = ovl_hash_bylower(sb, upperdentry, lowerdentry, index); bool is_dir; + unsigned long ino = 0;
if (!realinode) realinode = d_inode(lowerdentry); @@ -748,13 +760,14 @@ struct inode *ovl_get_inode(struct super if (!is_dir) nlink = ovl_get_nlink(lowerdentry, upperdentry, nlink); set_nlink(inode, nlink); + ino = key->i_ino; } else { /* Lower hardlink that will be broken on copy up */ inode = new_inode(sb); if (!inode) goto out_nomem; } - ovl_fill_inode(inode, realinode->i_mode, realinode->i_rdev); + ovl_fill_inode(inode, realinode->i_mode, realinode->i_rdev, ino); ovl_inode_init(inode, upperdentry, lowerdentry);
if (upperdentry && ovl_is_impuredir(upperdentry)) --- a/fs/overlayfs/util.c +++ b/fs/overlayfs/util.c @@ -279,12 +279,16 @@ void ovl_dentry_set_redirect(struct dent void ovl_inode_init(struct inode *inode, struct dentry *upperdentry, struct dentry *lowerdentry) { + struct inode *realinode = d_inode(upperdentry ?: lowerdentry); + if (upperdentry) OVL_I(inode)->__upperdentry = upperdentry; if (lowerdentry) OVL_I(inode)->lower = igrab(d_inode(lowerdentry));
- ovl_copyattr(d_inode(upperdentry ?: lowerdentry), inode); + ovl_copyattr(realinode, inode); + if (!inode->i_ino) + inode->i_ino = realinode->i_ino; }
void ovl_inode_update(struct inode *inode, struct dentry *upperdentry) @@ -299,6 +303,8 @@ void ovl_inode_update(struct inode *inod smp_wmb(); OVL_I(inode)->__upperdentry = upperdentry; if (inode_unhashed(inode)) { + if (!inode->i_ino) + inode->i_ino = upperinode->i_ino; inode->i_private = upperinode; __insert_inode_hash(inode, (unsigned long) upperinode); }