2.4.13-ac8

 fs

diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla/fs/open.c linux.ac/fs/open.c
--- linux.vanilla/fs/open.c   Thu Oct 25 16:26:39 2001
+++ linux.ac/fs/open.c   Mon Oct 15 09:12:15 2001
@@ -14,7 +14,7 @@
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/tty.h>
-#include <linux/iobuf.h>
+#include <linux/pagemap.h>
 
 #include <asm/uaccess.h>
 
@@ -71,20 +71,28 @@
    return error;
 }
 
+/*
+ * i_sem is taken outside i_truncate_sem because that is the
+ * order in which these locks are taken on the path
+ * generic_file_write->copy_from_user->handle_mm_fault->do_no_page
+ */
+
 int do_truncate(struct dentry *dentry, loff_t length)
 {
    struct inode *inode = dentry->d_inode;
    int error;
    struct iattr newattrs;
-
+   
    /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
    if (length < 0)
       return -EINVAL;
 
    down(&inode->i_sem);
+   down_write(&inode->i_truncate_sem);
    newattrs.ia_size = length;
    newattrs.ia_valid = ATTR_SIZE | ATTR_CTIME;
    error = notify_change(dentry, &newattrs);
+   up_write(&inode->i_truncate_sem);
    up(&inode->i_sem);
    return error;
 }
@@ -117,12 +125,8 @@
    if (error)
       goto dput_and_out;
 
-   error = -EROFS;
-   if (IS_RDONLY(inode))
-      goto dput_and_out;
-
    error = -EPERM;
-   if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
+   if (IS_APPEND(inode))
       goto dput_and_out;
 
    /*
@@ -674,16 +678,6 @@
    f->f_reada = 0;
    f->f_op = fops_get(inode->i_fop);
    file_move(f, &inode->i_sb->s_files);
-
-   /* preallocate kiobuf for O_DIRECT */
-   f->f_iobuf = NULL;
-   f->f_iobuf_lock = 0;
-   if (f->f_flags & O_DIRECT) {
-      error = alloc_kiovec(1, &f->f_iobuf);
-      if (error)
-         goto cleanup_all;
-   }
-
    if (f->f_op && f->f_op->open) {
       error = f->f_op->open(inode,f);
       if (error)
@@ -694,8 +688,6 @@
    return f;
 
 cleanup_all:
-   if (f->f_iobuf)
-      free_kiovec(1, &f->f_iobuf);
    fops_put(f->f_op);
    if (f->f_mode & FMODE_WRITE)
       put_write_access(inode);