linux-kernel - [PATCH 20/32] vfs: Make close() unmount the attached mount if so flagged [ver #8]

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Date:   Fri, 25 May 2018 01:07:34 +0100
From:   David Howells <dhowells@...hat.com>
To:     viro@...iv.linux.org.uk
Cc:     dhowells@...hat.com, linux-fsdevel@...r.kernel.org,
        linux-afs@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 20/32] vfs: Make close() unmount the attached mount if so
 flagged [ver #8]


---

 fs/file_table.c    |    4 ++++
 include/linux/fs.h |    4 +++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/file_table.c b/fs/file_table.c
index 7ec0b3e5f05d..dbbcc563748a 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -30,6 +30,7 @@
 #include <linux/atomic.h>
 
 #include "internal.h"
+#include "mount.h"
 
 /* sysctl tunables... */
 struct files_stat_struct files_stat = {
@@ -200,6 +201,9 @@ static void __fput(struct file *file)
 	eventpoll_release(file);
 	locks_remove_file(file);
 
+	if (unlikely(file->f_mode & FMODE_NEED_UNMOUNT))
+		__detach_mounts(dentry);
+
 	ima_file_free(file);
 	if (unlikely(file->f_flags & FASYNC)) {
 		if (file->f_op->fasync)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index e771803cc8dc..ba571c18e236 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -152,7 +152,9 @@ typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
 #define FMODE_NONOTIFY		((__force fmode_t)0x4000000)
 
 /* File is capable of returning -EAGAIN if I/O will block */
-#define FMODE_NOWAIT	((__force fmode_t)0x8000000)
+#define FMODE_NOWAIT		((__force fmode_t)0x8000000)
+/* File represents mount that needs unmounting */
+#define FMODE_NEED_UNMOUNT	((__force fmode_t)0x10000000)
 
 /*
  * Flag for rw_copy_check_uvector and compat_rw_copy_check_uvector