1 files changed, 45 insertions, 0 deletions

diff --git a/fs/proc/fd.c b/fs/proc/fd.c
index 913bef0d2a36..fc46d6fe080c 100644
--- a/fs/proc/fd.c
+++ b/fs/proc/fd.c
@@ -7,6 +7,7 @@
 #include <linux/namei.h>
 #include <linux/pid.h>
 #include <linux/ptrace.h>
+#include <linux/bitmap.h>
 #include <linux/security.h>
 #include <linux/file.h>
 #include <linux/seq_file.h>
@@ -279,6 +280,30 @@ out:
 	return 0;
 }
 
+static int proc_readfd_count(struct inode *inode, loff_t *count)
+{
+	struct task_struct *p = get_proc_task(inode);
+	struct fdtable *fdt;
+
+	if (!p)
+		return -ENOENT;
+
+	task_lock(p);
+	if (p->files) {
+		rcu_read_lock();
+
+		fdt = files_fdtable(p->files);
+		*count = bitmap_weight(fdt->open_fds, fdt->max_fds);
+
+		rcu_read_unlock();
+	}
+	task_unlock(p);
+
+	put_task_struct(p);
+
+	return 0;
+}
+
 static int proc_readfd(struct file *file, struct dir_context *ctx)
 {
 	return proc_readfd_common(file, ctx, proc_fd_instantiate);
@@ -319,9 +344,29 @@ int proc_fd_permission(struct user_namespace *mnt_userns,
 	return rv;
 }
 
+static int proc_fd_getattr(struct user_namespace *mnt_userns,
+			const struct path *path, struct kstat *stat,
+			u32 request_mask, unsigned int query_flags)
+{
+	struct inode *inode = d_inode(path->dentry);
+	int rv = 0;
+
+	generic_fillattr(&init_user_ns, inode, stat);
+
+	/* If it's a directory, put the number of open fds there */
+	if (S_ISDIR(inode->i_mode)) {
+		rv = proc_readfd_count(inode, &stat->size);
+		if (rv < 0)
+			return rv;
+	}
+
+	return rv;
+}
+
 const struct inode_operations proc_fd_inode_operations = {
 	.lookup		= proc_lookupfd,
 	.permission	= proc_fd_permission,
+	.getattr	= proc_fd_getattr,
 	.setattr	= proc_setattr,
 };