From: Miklos Szeredi <[EMAIL PROTECTED]>

Add a new attribute flag ATTR_OPEN, with the meaning: "truncation was
initiated by open() due to the O_TRUNC flag".

This way filesystems wanting to implement truncation within their
->open() method can ignore such truncate requests.

This is a quick & dirty hack, but it comes for free.

Signed-off-by: Miklos Szeredi <[EMAIL PROTECTED]>
---

Index: linux/fs/namei.c
===================================================================
--- linux.orig/fs/namei.c       2007-09-21 13:44:53.000000000 +0200
+++ linux/fs/namei.c    2007-09-21 13:45:14.000000000 +0200
@@ -1656,8 +1656,10 @@ int may_open(struct nameidata *nd, int a
                error = locks_verify_locked(inode);
                if (!error) {
                        DQUOT_INIT(inode);
-                       
-                       error = do_truncate(dentry, 0, ATTR_MTIME|ATTR_CTIME, 
NULL);
+
+                       error = do_truncate(dentry, 0,
+                                           ATTR_MTIME|ATTR_CTIME|ATTR_OPEN,
+                                           NULL);
                }
                put_write_access(inode);
                if (error)
Index: linux/include/linux/fs.h
===================================================================
--- linux.orig/include/linux/fs.h       2007-09-21 13:45:11.000000000 +0200
+++ linux/include/linux/fs.h    2007-09-21 13:45:14.000000000 +0200
@@ -337,6 +337,7 @@ typedef void (dio_iodone_t)(struct kiocb
 #define ATTR_KILL_SGID 4096
 #define ATTR_FILE      8192
 #define ATTR_KILL_PRIV 16384
+#define ATTR_OPEN      32768   /* Truncating from open(O_TRUNC) */
 
 /*
  * This is the Inode Attributes structure, used for notify_change().  It
@@ -1526,7 +1527,7 @@ static inline int break_lease(struct ino
 
 /* fs/open.c */
 
-extern int do_truncate(struct dentry *, loff_t start, unsigned int time_attrs,
+extern int do_truncate(struct dentry *, loff_t start, unsigned int attrs,
                       struct file *filp);
 extern long do_sys_open(int fdf, const char __user *filename, int flags,
                        int mode);
Index: linux/fs/open.c
===================================================================
--- linux.orig/fs/open.c        2007-09-21 13:45:04.000000000 +0200
+++ linux/fs/open.c     2007-09-21 13:45:14.000000000 +0200
@@ -194,7 +194,7 @@ out:
        return error;
 }
 
-int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
+int do_truncate(struct dentry *dentry, loff_t length, unsigned int attrs,
        struct file *filp)
 {
        int err;
@@ -205,7 +205,7 @@ int do_truncate(struct dentry *dentry, l
                return -EINVAL;
 
        newattrs.ia_size = length;
-       newattrs.ia_valid = ATTR_SIZE | time_attrs;
+       newattrs.ia_valid = ATTR_SIZE | attrs;
        if (filp) {
                newattrs.ia_file = filp;
                newattrs.ia_valid |= ATTR_FILE;

--
-
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