[patch 08/96] vfs: separate FMODE_PREAD/FMODE_PWRITE into separate flags

[Greg KH]

2.6.27-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Paul Turner <pjt@xxxxxxxxxx>

commit 55ec82176eca52e4e0530a82a0eb59160a1a95a1 upstream.

Separate FMODE_PREAD and FMODE_PWRITE into separate flags to reflect the
reality that the read and write paths may have independent restrictions.

A git grep verifies that these flags are always cleared together so this
new behavior will only apply to interfaces that change to clear flags
individually.

This is required for "seq_file: properly cope with pread", a post-2.6.25
regression fix.

[akpm@xxxxxxxxxxxxxxxxxxxx: add comment]
Signed-off-by: Paul Turner <pjt@xxxxxxxxxx>
Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx>
Cc:  Alexey Dobriyan <adobriyan@xxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 include/linux/fs.h |   12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -63,17 +63,23 @@ extern int dir_notify_enable;
 #define MAY_ACCESS 16
 #define MAY_OPEN 32
 
+/*
+ * flags in file.f_mode.  Note that FMODE_READ and FMODE_WRITE must correspond
+ * to O_WRONLY and O_RDWR via the strange trick in __dentry_open()
+ */
+
 /* file is open for reading */
 #define FMODE_READ		(1)
 /* file is open for writing */
 #define FMODE_WRITE		(2)
 /* file is seekable */
 #define FMODE_LSEEK		(4)
-/* file can be accessed using pread/pwrite */
+/* file can be accessed using pread */
 #define FMODE_PREAD		(8)
-#define FMODE_PWRITE		FMODE_PREAD	/* These go hand in hand */
+/* file can be accessed using pwrite */
+#define FMODE_PWRITE		(16)
 /* File is opened for execution with sys_execve / sys_uselib */
-#define FMODE_EXEC		(16)
+#define FMODE_EXEC		(32)
 
 #define RW_MASK		1
 #define RWA_MASK	2


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