- 根目录:
- fs
- adfs
- inode.c
/*
* linux/fs/adfs/inode.c
*
* Copyright (C) 1997-1999 Russell King
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/buffer_head.h>
#include <linux/writeback.h>
#include "adfs.h"
/*
* Lookup/Create a block at offset 'block' into 'inode'. We currently do
* not support creation of new blocks, so we return -EIO for this case.
*/
static int
adfs_get_block(struct inode *inode, sector_t block, struct buffer_head *bh,
int create)
{
if (!create) {
if (block >= inode->i_blocks)
goto abort_toobig;
block = __adfs_block_map(inode->i_sb, inode->i_ino, block);
if (block)
map_bh(bh, inode->i_sb, block);
return 0;
}
/* don't support allocation of blocks yet */
return -EIO;
abort_toobig:
return 0;
}
static int adfs_writepage(struct page *page, struct writeback_control *wbc)
{
return block_write_full_page(page, adfs_get_block, wbc);
}
static int adfs_readpage(struct file *file, struct page *page)
{
return block_read_full_page(page, adfs_get_block);
}
static int adfs_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)
{
int ret;
*pagep = NULL;
ret = cont_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
adfs_get_block,
&ADFS_I(mapping->host)->mmu_private);
if (unlikely(ret)) {
loff_t isize = mapping->host->i_size;
if (pos + len > isize)
vmtruncate(mapping->host, isize);
}
return ret;
}
static sector_t _adfs_bmap(struct address_space *mapping, sector_t block)
{
return generic_block_bmap(mapping, block, adfs_get_block);
}
static const struct address_space_operations adfs_aops = {
.readpage = adfs_readpage,
.writepage = adfs_writepage,
.write_begin = adfs_write_begin,
.write_end = generic_write_end,
.bmap = _adfs_bmap
};
/*
* Convert ADFS attributes and filetype to Linux permission.
*/
static umode_t
adfs_atts2mode(struct super_block *sb, struct inode *inode)
{
unsigned int attr = ADFS_I(inode)->attr;
umode_t mode, rmask;
struct adfs_sb_info *asb = ADFS_SB(sb);
if (attr & ADFS_NDA_DIRECTORY) {
mode = S_IRUGO & asb->s_owner_mask;
return S_IFDIR | S_IXUGO | mode;
}
switch (ADFS_I(inode)->filetype) {
case 0xfc0: /* LinkFS */
return S_IFLNK|S_IRWXUGO;
case 0xfe6: /* UnixExec */
rmask = S_IRUGO | S_IXUGO;
break;
default:
rmask = S_IRUGO;
}
mode = S_IFREG;
if (attr & ADFS_NDA_OWNER_READ)
mode |= rmask & asb->s_owner_mask;
if (attr & ADFS_NDA_OWNER_WRITE)
mode |= S_IWUGO & asb->s_owner_mask;
if (attr & ADFS_NDA_PUBLIC_READ)
mode |= rmask & asb->s_other_mask;
if (attr & ADFS_NDA_PUBLIC_WRITE)
mode |= S_IWUGO & asb->s_other_mask;
return mode;
}
/*
* Convert Linux permission to ADFS attribute. We try to do the reverse
* of atts2mode, but there is not a 1:1 translation.
*/
static int
adfs_mode2atts(struct super_block *sb, struct inode *inode)
{
umode_t mode;
int attr;
struct adfs_sb_info *asb = ADFS_SB(sb);
/* FIXME: should we be able to alter a link? */
if (S_ISLNK(inode->i_mode))
return ADFS_I(inode)->attr;
if (S_ISDIR(inode->i_mode))
attr = ADFS_NDA_DIRECTORY;
else
attr = 0;
mode = inode->i_mode & asb->s_owner_mask;
if (mode & S_IRUGO)
attr |= ADFS_NDA_OWNER_READ;
if (mode & S_IWUGO)
attr |= ADFS_NDA_OWNER_WRITE;
mode = inode->i_mode & asb->s_other_mask;
mode &= ~asb->s_owner_mask;
if (mode & S_IRUGO)
attr |= ADFS_NDA_PUBLIC_READ;
if (mode & S_IWUGO)
attr |= ADFS_NDA_PUBLIC_WRITE;
return attr;
}
/*
* Convert an ADFS time to Unix time. ADFS has a 40-bit centi-second time
* referenced to 1 Jan 1900 (til 2248) so we need to discard 2208988800 seconds
* of time to convert from RISC OS epoch to Unix epoch.
*/
static void
adfs_adfs2unix_time(struct timespec *tv, struct inode *inode)
{
unsigned int high, low;
/* 01 Jan 1970 00:00:00 (Unix epoch) as nanoseconds since
* 01 Jan 1900 00:00:00 (RISC OS epoch)
*/
static const s64 nsec_unix_epoch_diff_risc_os_epoch =
2208988800000000000LL;
s64 nsec;
if (ADFS_I(inode)->stamped == 0)
goto cur_time;
high = ADFS_I(inode)->loadaddr & 0xFF; /* top 8 bits of timestamp */
low = ADFS_I(inode)->execaddr; /* bottom 32 bits of timestamp */
/* convert 40-bit centi-seconds to 32-bit seconds
* going via nanoseconds to retain precision
*/
nsec = (((s64) high << 32) | (s64) low) * 10000000; /* cs to ns */
/* Files dated pre 01 Jan 1970 00:00:00. */
if (nsec < nsec_unix_epoch_diff_risc_os_epoch)
goto too_early;
/* convert from RISC OS to Unix epoch */
nsec -= nsec_unix_epoch_diff_risc_os_epoch;
*tv = ns_to_timespec(nsec);
return;
cur_time:
*tv = CURRENT_TIME;
return;
too_early:
tv->tv_sec = tv->tv_nsec = 0;
return;
}
/*
* Convert an Unix time to ADFS time. We only do this if the entry has a
* time/date stamp already.
*/
static void
adfs_unix2adfs_time(struct inode *inode, unsigned int secs)
{
unsigned int high, low;
if (ADFS_I(inode)->stamped) {
/* convert 32-bit seconds to 40-bit centi-seconds */
low = (secs & 255) * 100;
high = (secs / 256) * 100 + (low >> 8) + 0x336e996a;
ADFS_I(inode)->loadaddr = (high >> 24) |
(ADFS_I(inode)->loadaddr & ~0xff);
ADFS_I(inode)->execaddr = (low & 255) | (high << 8);
}
}
/*
* Fill in the inode information from the object information.
*
* Note that this is an inode-less filesystem, so we can't use the inode
* number to reference the metadata on the media. Instead, we use the
* inode number to hold the object ID, which in turn will tell us where
* the data is held. We also save the parent object ID, and with these
* two, we can locate the metadata.
*
* This does mean that we rely on an objects parent remaining the same at
* all times - we cannot cope with a cross-directory rename (yet).
*/
struct inode *
adfs_iget(struct super_block *sb, struct object_info *obj)
{
struct inode *inode;
inode = new_inode(sb);
if (!inode)
goto out;
inode->i_uid = ADFS_SB(sb)->s_uid;
inode->i_gid = ADFS_SB(sb)->s_gid;
inode->i_ino = obj->file_id;
inode->i_size = obj->size;
inode->i_nlink = 2;
inode->i_blocks = (inode->i_size + sb->s_blocksize - 1) >>
sb->s_blocksize_bits;
/*
* we need to save the parent directory ID so that
* write_inode can update the directory information
* for this file. This will need special handling
* for cross-directory renames.
*/
ADFS_I(inode)->parent_id = obj->parent_id;
ADFS_I(inode)->loadaddr = obj->loadaddr;
ADFS_I(inode)->execaddr = obj->execaddr;
ADFS_I(inode)->attr = obj->attr;
ADFS_I(inode)->filetype = obj->filetype;
ADFS_I(inode)->stamped = ((obj->loadaddr & 0xfff00000) == 0xfff00000);
inode->i_mode = adfs_atts2mode(sb, inode);
adfs_adfs2unix_time(&inode->i_mtime, inode);
inode->i_atime = inode->i_mtime;
inode->i_ctime = inode->i_mtime;
if (S_ISDIR(inode->i_mode)) {
inode->i_op = &adfs_dir_inode_operations;
inode->i_fop = &adfs_dir_operations;
} else if (S_ISREG(inode->i_mode)) {
inode->i_op = &adfs_file_inode_operations;
inode->i_fop = &adfs_file_operations;
inode->i_mapping->a_ops = &adfs_aops;
ADFS_I(inode)->mmu_private = inode->i_size;
}
insert_inode_hash(inode);
out:
return inode;
}
/*
* Validate and convert a changed access mode/time to their ADFS equivalents.
* adfs_write_inode will actually write the information back to the directory
* later.
*/
int
adfs_notify_change(struct dentry *dentry, struct iattr *attr)
{
struct inode *inode = dentry->d_inode;
struct super_block *sb = inode->i_sb;
unsigned int ia_valid = attr->ia_valid;
int error;
error = inode_change_ok(inode, attr);
/*
* we can't change the UID or GID of any file -
* we have a global UID/GID in the superblock
*/
if ((ia_valid & ATTR_UID && attr->ia_uid != ADFS_SB(sb)->s_uid) ||
(ia_valid & ATTR_GID && attr->ia_gid != ADFS_SB(sb)->s_gid))
error = -EPERM;
if (error)
goto out;
/* XXX: this is missing some actual on-disk truncation.. */
if (ia_valid & ATTR_SIZE)
truncate_setsize(inode, attr->ia_size);
if (ia_valid & ATTR_MTIME) {
inode->i_mtime = attr->ia_mtime;
adfs_unix2adfs_time(inode, attr->ia_mtime.tv_sec);
}
/*
* FIXME: should we make these == to i_mtime since we don't
* have the ability to represent them in our filesystem?
*/
if (ia_valid & ATTR_ATIME)
inode->i_atime = attr->ia_atime;
if (ia_valid & ATTR_CTIME)
inode->i_ctime = attr->ia_ctime;
if (ia_valid & ATTR_MODE) {
ADFS_I(inode)->attr = adfs_mode2atts(sb, inode);
inode->i_mode = adfs_atts2mode(sb, inode);
}
/*
* FIXME: should we be marking this inode dirty even if
* we don't have any metadata to write back?
*/
if (ia_valid & (ATTR_SIZE | ATTR_MTIME | ATTR_MODE))
mark_inode_dirty(inode);
out:
return error;
}
/*
* write an existing inode back to the directory, and therefore the disk.
* The adfs-specific inode data has already been updated by
* adfs_notify_change()
*/
int adfs_write_inode(struct inode *inode, struct writeback_control *wbc)
{
struct super_block *sb = inode->i_sb;
struct object_info obj;
int ret;
obj.file_id = inode->i_ino;
obj.name_len = 0;
obj.parent_id = ADFS_I(inode)->parent_id;
obj.loadaddr = ADFS_I(inode)->loadaddr;
obj.execaddr = ADFS_I(inode)->execaddr;
obj.attr = ADFS_I(inode)->attr;
obj.size = inode->i_size;
ret = adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL);
return ret;
}