From 406cd91533dcc5e82ef2373c39e6a531d944131e Mon Sep 17 00:00:00 2001 From: Benjamin Coddington Date: Fri, 13 Sep 2019 08:29:02 -0400 Subject: [PATCH] NFS: Refactor nfs_instantiate() for dentry referencing callers Since commit b0c6108ecf64 ("nfs_instantiate(): prevent multiple aliases for directory inode"), nfs_instantiate() may succeed without actually instantiating the dentry that was passed in. That can be problematic for some callers in NFSv3, so this patch breaks things up so we can get the actual dentry obtained. Signed-off-by: Benjamin Coddington Signed-off-by: Anna Schumaker --- fs/nfs/dir.c | 41 +++++++++++++++++++++++++++-------------- include/linux/nfs_fs.h | 3 +++ 2 files changed, 30 insertions(+), 14 deletions(-) diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index 8d501093660f..d1bbf2fb6ac7 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -1669,24 +1669,23 @@ static int nfs4_lookup_revalidate(struct dentry *dentry, unsigned int flags) #endif /* CONFIG_NFSV4 */ -/* - * Code common to create, mkdir, and mknod. - */ -int nfs_instantiate(struct dentry *dentry, struct nfs_fh *fhandle, +struct dentry * +nfs_add_or_obtain(struct dentry *dentry, struct nfs_fh *fhandle, struct nfs_fattr *fattr, struct nfs4_label *label) { struct dentry *parent = dget_parent(dentry); struct inode *dir = d_inode(parent); struct inode *inode; - struct dentry *d; - int error = -EACCES; + struct dentry *d = NULL; + int error; d_drop(dentry); /* We may have been initialized further down */ if (d_really_is_positive(dentry)) goto out; + if (fhandle->size == 0) { error = NFS_PROTO(dir)->lookup(dir, &dentry->d_name, fhandle, fattr, NULL); if (error) @@ -1702,18 +1701,32 @@ int nfs_instantiate(struct dentry *dentry, struct nfs_fh *fhandle, } inode = nfs_fhget(dentry->d_sb, fhandle, fattr, label); d = d_splice_alias(inode, dentry); - if (IS_ERR(d)) { - error = PTR_ERR(d); - goto out_error; - } - dput(d); out: dput(parent); - return 0; + return d; out_error: nfs_mark_for_revalidate(dir); - dput(parent); - return error; + d = ERR_PTR(error); + goto out; +} +EXPORT_SYMBOL_GPL(nfs_add_or_obtain); + +/* + * Code common to create, mkdir, and mknod. + */ +int nfs_instantiate(struct dentry *dentry, struct nfs_fh *fhandle, + struct nfs_fattr *fattr, + struct nfs4_label *label) +{ + struct dentry *d; + + d = nfs_add_or_obtain(dentry, fhandle, fattr, label); + if (IS_ERR(d)) + return PTR_ERR(d); + + /* Callers don't care */ + dput(d); + return 0; } EXPORT_SYMBOL_GPL(nfs_instantiate); diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h index 0a11712a80e3..570a60c2f4f4 100644 --- a/include/linux/nfs_fs.h +++ b/include/linux/nfs_fs.h @@ -490,6 +490,9 @@ extern const struct file_operations nfs_dir_operations; extern const struct dentry_operations nfs_dentry_operations; extern void nfs_force_lookup_revalidate(struct inode *dir); +extern struct dentry *nfs_add_or_obtain(struct dentry *dentry, + struct nfs_fh *fh, struct nfs_fattr *fattr, + struct nfs4_label *label); extern int nfs_instantiate(struct dentry *dentry, struct nfs_fh *fh, struct nfs_fattr *fattr, struct nfs4_label *label); extern int nfs_may_open(struct inode *inode, const struct cred *cred, int openflags); -- 2.49.0