Viewing file:  ioctl.c (2.39 KB) -rw-r--r--
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/*
* Copyright 2000 by Hans Reiser, licensing governed by reiserfs/README
*/
#include <linux/fs.h>
#include <linux/reiserfs_fs.h>
#include <linux/sched.h>
#include <asm/uaccess.h>
#include <linux/smp_lock.h>
#include <linux/locks.h>
/*
** reiserfs_ioctl - handler for ioctl for inode
** supported commands:
** 1) REISERFS_IOC_UNPACK - try to unpack tail from direct item into indirect
** and prevent packing file (argument arg has to be non-zero)
** 2) That's all for a while ...
*/
int reiserfs_ioctl (struct inode * inode, struct file * filp, unsigned int cmd,
unsigned long arg)
{
switch (cmd) {
case REISERFS_IOC_UNPACK:
if (arg)
return reiserfs_unpack (inode, filp);
default:
return -ENOTTY;
}
}
/*
** reiserfs_unpack
** Function try to convert tail from direct item into indirect.
** It set up nopack attribute in the inode.u.reiserfs_i.nopack
*/
int reiserfs_unpack (struct inode * inode, struct file * filp)
{
int retval = 0;
int index ;
struct page *page ;
unsigned long write_from ;
unsigned long blocksize = inode->i_sb->s_blocksize ;
if (inode->i_size == 0) {
return -EINVAL ;
}
/* ioctl already done */
if (inode->u.reiserfs_i.i_flags & i_nopack_mask) {
return 0 ;
}
lock_kernel();
/* we need to make sure nobody is changing the file size beneath
** us
*/
down(&inode->i_sem) ;
write_from = inode->i_size & (blocksize - 1) ;
/* if we are on a block boundary, we are already unpacked. */
if ( write_from == 0) {
inode->u.reiserfs_i.i_flags |= i_nopack_mask;
goto out ;
}
/* we unpack by finding the page with the tail, and calling
** reiserfs_prepare_write on that page. This will force a
** reiserfs_get_block to unpack the tail for us.
*/
index = inode->i_size >> PAGE_CACHE_SHIFT ;
page = grab_cache_page(inode->i_mapping, index) ;
retval = -ENOMEM;
if (!page) {
goto out ;
}
retval = reiserfs_prepare_write(NULL, page, write_from, blocksize) ;
if (retval)
goto out_unlock ;
/* conversion can change page contents, must flush */
flush_dcache_page(page) ;
inode->u.reiserfs_i.i_flags |= i_nopack_mask;
kunmap(page) ; /* mapped by prepare_write */
out_unlock:
UnlockPage(page) ;
page_cache_release(page) ;
out:
up(&inode->i_sem) ;
unlock_kernel();
return retval;
}
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