nfsd: vfs_mkdir() might succeed leaving dentry negative unhashed (3819bb0d) · Commits · 戴 / test

That can (and does, on some filesystems) happen - ->mkdir() (and thus vfs_mkdir()) can legitimately leave its argument negative and just unhash it, counting upon the lookup to pick the object we'd created next time we try to look at that name. Some vfs_mkdir() callers forget about that possibility... Acked-by:

J. Bruce Fields <bfields@redhat.com> Signed-off-by:

Al Viro <viro@zeniv.linux.org.uk>

fs/nfsd/vfs.c

+22 −0

Original line number	Diff line number	Diff line
		@@ -1201,6 +1201,28 @@ nfsd_create_locked(struct svc_rqst rqstp, struct svc_fh fhp,
		break;
		case S_IFDIR:
		host_err = vfs_mkdir(dirp, dchild, iap->ia_mode);
		if (!host_err && unlikely(d_unhashed(dchild))) {
		struct dentry *d;
		d = lookup_one_len(dchild->d_name.name,
		dchild->d_parent,
		dchild->d_name.len);
		if (IS_ERR(d)) {
		host_err = PTR_ERR(d);
		break;
		}
		if (unlikely(d_is_negative(d))) {
		dput(d);
		err = nfserr_serverfault;
		goto out;
		}
		dput(resfhp->fh_dentry);
		resfhp->fh_dentry = dget(d);
		err = fh_update(resfhp);
		dput(dchild);
		dchild = d;
		if (err)
		goto out;
		}
		break;
		case S_IFCHR:
		case S_IFBLK:

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