linux/fs/adfs/inode.c
Christian Brauner c1632a0f11
fs: port ->setattr() to pass mnt_idmap
Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-01-19 09:24:02 +01:00

370 lines
9.5 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* linux/fs/adfs/inode.c
*
* Copyright (C) 1997-1999 Russell King
*/
#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, ADFS_I(inode)->indaddr,
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_read_folio(struct file *file, struct folio *folio)
{
return block_read_full_folio(folio, adfs_get_block);
}
static void adfs_write_failed(struct address_space *mapping, loff_t to)
{
struct inode *inode = mapping->host;
if (to > inode->i_size)
truncate_pagecache(inode, inode->i_size);
}
static int adfs_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len,
struct page **pagep, void **fsdata)
{
int ret;
*pagep = NULL;
ret = cont_write_begin(file, mapping, pos, len, pagep, fsdata,
adfs_get_block,
&ADFS_I(mapping->host)->mmu_private);
if (unlikely(ret))
adfs_write_failed(mapping, pos + len);
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 = {
.dirty_folio = block_dirty_folio,
.invalidate_folio = block_invalidate_folio,
.read_folio = adfs_read_folio,
.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_filetype(ADFS_I(inode)->loadaddr)) {
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 ia_mode)
{
struct adfs_sb_info *asb = ADFS_SB(sb);
umode_t mode;
int attr;
/* FIXME: should we be able to alter a link? */
if (S_ISLNK(inode->i_mode))
return ADFS_I(inode)->attr;
/* Directories do not have read/write permissions on the media */
if (S_ISDIR(inode->i_mode))
return ADFS_NDA_DIRECTORY;
attr = 0;
mode = ia_mode & asb->s_owner_mask;
if (mode & S_IRUGO)
attr |= ADFS_NDA_OWNER_READ;
if (mode & S_IWUGO)
attr |= ADFS_NDA_OWNER_WRITE;
mode = ia_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;
}
static const s64 nsec_unix_epoch_diff_risc_os_epoch = 2208988800000000000LL;
/*
* 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 timespec64 *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)
*/
s64 nsec;
if (!adfs_inode_is_stamped(inode))
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_timespec64(nsec);
return;
cur_time:
*tv = current_time(inode);
return;
too_early:
tv->tv_sec = tv->tv_nsec = 0;
return;
}
/* Convert an Unix time to ADFS time for an entry that is already stamped. */
static void adfs_unix2adfs_time(struct inode *inode,
const struct timespec64 *ts)
{
s64 cs, nsec = timespec64_to_ns(ts);
/* convert from Unix to RISC OS epoch */
nsec += nsec_unix_epoch_diff_risc_os_epoch;
/* convert from nanoseconds to centiseconds */
cs = div_s64(nsec, 10000000);
cs = clamp_t(s64, cs, 0, 0xffffffffff);
ADFS_I(inode)->loadaddr &= ~0xff;
ADFS_I(inode)->loadaddr |= (cs >> 32) & 0xff;
ADFS_I(inode)->execaddr = cs;
}
/*
* 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->indaddr;
inode->i_size = obj->size;
set_nlink(inode, 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)->indaddr = obj->indaddr;
ADFS_I(inode)->loadaddr = obj->loadaddr;
ADFS_I(inode)->execaddr = obj->execaddr;
ADFS_I(inode)->attr = obj->attr;
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;
}
inode_fake_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 mnt_idmap *idmap, struct dentry *dentry,
struct iattr *attr)
{
struct inode *inode = d_inode(dentry);
struct super_block *sb = inode->i_sb;
unsigned int ia_valid = attr->ia_valid;
int error;
error = setattr_prepare(&nop_mnt_idmap, dentry, 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 && !uid_eq(attr->ia_uid, ADFS_SB(sb)->s_uid)) ||
(ia_valid & ATTR_GID && !gid_eq(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 && adfs_inode_is_stamped(inode)) {
adfs_unix2adfs_time(inode, &attr->ia_mtime);
adfs_adfs2unix_time(&inode->i_mtime, inode);
}
/*
* 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, attr->ia_mode);
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;
obj.indaddr = ADFS_I(inode)->indaddr;
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;
return adfs_dir_update(sb, &obj, wbc->sync_mode == WB_SYNC_ALL);
}