From: Pekka Enberg <[EMAIL PROTECTED]>
This adds a f_light flag to struct file to indicate that the file was
looked up with fget_light(). Needed by revoke to ensure we don't
close a file pointer while someone is using it without actually
holding a reference.
These bits were taken from the forced unmount patches by Tigran
Aivazian.
Signed-off-by: Pekka Enberg <[EMAIL PROTECTED]>
---
fs/file_table.c | 1 +
include/linux/file.h | 14 ++++++++++++++
include/linux/fs.h | 2 ++
3 files changed, 17 insertions(+)
Index: uml-2.6/fs/file_table.c
===================================================================
--- uml-2.6.orig/fs/file_table.c 2007-03-08 10:24:24.000000000 +0200
+++ uml-2.6/fs/file_table.c 2007-03-08 10:24:31.000000000 +0200
@@ -219,6 +219,7 @@
*fput_needed = 0;
if (likely((atomic_read(&files->count) == 1))) {
file = fcheck_files(files, fd);
+ set_f_light(file);
} else {
rcu_read_lock();
file = fcheck_files(files, fd);
Index: uml-2.6/include/linux/file.h
===================================================================
--- uml-2.6.orig/include/linux/file.h 2007-03-08 10:24:24.000000000 +0200
+++ uml-2.6/include/linux/file.h 2007-03-08 10:24:31.000000000 +0200
@@ -6,6 +6,7 @@
#define __LINUX_FILE_H
#include <asm/atomic.h>
+#include <linux/fs.h>
#include <linux/posix_types.h>
#include <linux/compiler.h>
#include <linux/spinlock.h>
@@ -62,10 +63,23 @@
extern void FASTCALL(__fput(struct file *));
extern void FASTCALL(fput(struct file *));
+static inline void clear_f_light(struct file *file)
+{
+ file->f_light = 0;
+}
+
+static inline void set_f_light(struct file *file)
+{
+ if (file)
+ file->f_light = 1;
+}
+
static inline void fput_light(struct file *file, int fput_needed)
{
if (unlikely(fput_needed))
fput(file);
+ else
+ clear_f_light(file);
}
extern struct file * FASTCALL(fget(unsigned int fd));
Index: uml-2.6/include/linux/fs.h
===================================================================
--- uml-2.6.orig/include/linux/fs.h 2007-03-08 10:24:24.000000000 +0200
+++ uml-2.6/include/linux/fs.h 2007-03-08 10:24:31.000000000 +0200
@@ -739,6 +739,8 @@
struct list_head f_ep_links;
spinlock_t f_ep_lock;
#endif /* #ifdef CONFIG_EPOLL */
+ /* This instance is being used without holding a reference. */
+ int f_light;
struct address_space *f_mapping;
};
extern spinlock_t files_lock;
-
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