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Linux Cross Reference
Linux-2.6.17/fs/ext2/xip.c

Version: ~ [ 2.6.16 ] ~ [ 2.6.17 ] ~
Architecture: ~ [ ia64 ] ~ [ i386 ] ~ [ arm ] ~ [ ppc ] ~ [ sparc64 ] ~ 
  1 /*
  2  *  linux/fs/ext2/xip.c
  3  *
  4  * Copyright (C) 2005 IBM Corporation
  5  * Author: Carsten Otte (cotte@de.ibm.com)
  6  */
  7 
  8 #include <linux/mm.h>
  9 #include <linux/fs.h>
 10 #include <linux/genhd.h>
 11 #include <linux/buffer_head.h>
 12 #include <linux/ext2_fs_sb.h>
 13 #include <linux/ext2_fs.h>
 14 #include "ext2.h"
 15 #include "xip.h"
 16 
 17 static inline int
 18 __inode_direct_access(struct inode *inode, sector_t sector,
 19                       unsigned long *data)
 20 {
 21         BUG_ON(!inode->i_sb->s_bdev->bd_disk->fops->direct_access);
 22         return inode->i_sb->s_bdev->bd_disk->fops
 23                 ->direct_access(inode->i_sb->s_bdev,sector,data);
 24 }
 25 
 26 static inline int
 27 __ext2_get_sector(struct inode *inode, sector_t offset, int create,
 28                    sector_t *result)
 29 {
 30         struct buffer_head tmp;
 31         int rc;
 32 
 33         memset(&tmp, 0, sizeof(struct buffer_head));
 34         rc = ext2_get_block(inode, offset/ (PAGE_SIZE/512), &tmp,
 35                             create);
 36         *result = tmp.b_blocknr;
 37 
 38         /* did we get a sparse block (hole in the file)? */
 39         if (!tmp.b_blocknr && !rc) {
 40                 BUG_ON(create);
 41                 rc = -ENODATA;
 42         }
 43 
 44         return rc;
 45 }
 46 
 47 int
 48 ext2_clear_xip_target(struct inode *inode, int block)
 49 {
 50         sector_t sector = block * (PAGE_SIZE/512);
 51         unsigned long data;
 52         int rc;
 53 
 54         rc = __inode_direct_access(inode, sector, &data);
 55         if (!rc)
 56                 clear_page((void*)data);
 57         return rc;
 58 }
 59 
 60 void ext2_xip_verify_sb(struct super_block *sb)
 61 {
 62         struct ext2_sb_info *sbi = EXT2_SB(sb);
 63 
 64         if ((sbi->s_mount_opt & EXT2_MOUNT_XIP) &&
 65             !sb->s_bdev->bd_disk->fops->direct_access) {
 66                 sbi->s_mount_opt &= (~EXT2_MOUNT_XIP);
 67                 ext2_warning(sb, __FUNCTION__,
 68                              "ignoring xip option - not supported by bdev");
 69         }
 70 }
 71 
 72 struct page *
 73 ext2_get_xip_page(struct address_space *mapping, sector_t offset,
 74                    int create)
 75 {
 76         int rc;
 77         unsigned long data;
 78         sector_t sector;
 79 
 80         /* first, retrieve the sector number */
 81         rc = __ext2_get_sector(mapping->host, offset, create, &sector);
 82         if (rc)
 83                 goto error;
 84 
 85         /* retrieve address of the target data */
 86         rc = __inode_direct_access
 87                 (mapping->host, sector * (PAGE_SIZE/512), &data);
 88         if (!rc)
 89                 return virt_to_page(data);
 90 
 91  error:
 92         return ERR_PTR(rc);
 93 }
 94
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