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