vfs: separate FMODE_PREAD/FMODE_PWRITE into separate flags

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@linux-foundation.org: add comment]
Signed-off-by: Paul Turner <pjt@google.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc:  Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 1888da76510676120e503cc8a95d99c5a83eed71..909e13ef520c1ffc7ddb5535f0acd007d00166aa 100644 (file)
--- 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