Revision 0a4c56c80f90797e9b9f8426c6aae4c0cf1c9785 authored by Linus Torvalds on 29 August 2020, 20:50:56 UTC, committed by Linus Torvalds on 29 August 2020, 20:50:56 UTC
Commit ef91bb196b0d ("kernel.h: Silence sparse warning in
lower_32_bits") caused new warnings to show in the fsldma driver, but
that commit was not to blame: it only exposed some very incorrect code
that tried to take the low 32 bits of an address.
That made no sense for multiple reasons, the most notable one being that
that code was intentionally limited to only 32-bit ppc builds, so "only
low 32 bits of an address" was completely nonsensical. There were no
high bits to mask off to begin with.
But even more importantly fropm a correctness standpoint, turning the
address into an integer then caused the subsequent address arithmetic to
be completely wrong too, and the "+1" actually incremented the address
by one, rather than by four.
Which again was incorrect, since the code was reading two 32-bit values
and trying to make a 64-bit end result of it all. Surprisingly, the
iowrite64() did not suffer from the same odd and incorrect model.
This code has never worked, but it's questionable whether anybody cared:
of the two users that actually read the 64-bit value (by way of some C
preprocessor hackery and eventually the 'get_cdar()' inline function),
one of them explicitly ignored the value, and the other one might just
happen to work despite the incorrect value being read.
This patch at least makes it not fail the build any more, and makes the
logic superficially sane. Whether it makes any difference to the code
_working_ or not shall remain a mystery.
Compile-tested-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent e77aee1
cache.c
// SPDX-License-Identifier: GPL-2.0
/*
* Cache operations for Coda.
* For Linux 2.1: (C) 1997 Carnegie Mellon University
* For Linux 2.3: (C) 2000 Carnegie Mellon University
*
* Carnegie Mellon encourages users of this code to contribute improvements
* to the Coda project http://www.coda.cs.cmu.edu/ <coda@cs.cmu.edu>.
*/
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/time.h>
#include <linux/fs.h>
#include <linux/stat.h>
#include <linux/errno.h>
#include <linux/uaccess.h>
#include <linux/string.h>
#include <linux/list.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/coda.h>
#include "coda_psdev.h"
#include "coda_linux.h"
#include "coda_cache.h"
static atomic_t permission_epoch = ATOMIC_INIT(0);
/* replace or extend an acl cache hit */
void coda_cache_enter(struct inode *inode, int mask)
{
struct coda_inode_info *cii = ITOC(inode);
spin_lock(&cii->c_lock);
cii->c_cached_epoch = atomic_read(&permission_epoch);
if (!uid_eq(cii->c_uid, current_fsuid())) {
cii->c_uid = current_fsuid();
cii->c_cached_perm = mask;
} else
cii->c_cached_perm |= mask;
spin_unlock(&cii->c_lock);
}
/* remove cached acl from an inode */
void coda_cache_clear_inode(struct inode *inode)
{
struct coda_inode_info *cii = ITOC(inode);
spin_lock(&cii->c_lock);
cii->c_cached_epoch = atomic_read(&permission_epoch) - 1;
spin_unlock(&cii->c_lock);
}
/* remove all acl caches */
void coda_cache_clear_all(struct super_block *sb)
{
atomic_inc(&permission_epoch);
}
/* check if the mask has been matched against the acl already */
int coda_cache_check(struct inode *inode, int mask)
{
struct coda_inode_info *cii = ITOC(inode);
int hit;
spin_lock(&cii->c_lock);
hit = (mask & cii->c_cached_perm) == mask &&
uid_eq(cii->c_uid, current_fsuid()) &&
cii->c_cached_epoch == atomic_read(&permission_epoch);
spin_unlock(&cii->c_lock);
return hit;
}
/* Purging dentries and children */
/* The following routines drop dentries which are not
in use and flag dentries which are in use to be
zapped later.
The flags are detected by:
- coda_dentry_revalidate (for lookups) if the flag is C_PURGE
- coda_dentry_delete: to remove dentry from the cache when d_count
falls to zero
- an inode method coda_revalidate (for attributes) if the
flag is C_VATTR
*/
/* this won't do any harm: just flag all children */
static void coda_flag_children(struct dentry *parent, int flag)
{
struct dentry *de;
spin_lock(&parent->d_lock);
list_for_each_entry(de, &parent->d_subdirs, d_child) {
/* don't know what to do with negative dentries */
if (d_inode(de) )
coda_flag_inode(d_inode(de), flag);
}
spin_unlock(&parent->d_lock);
return;
}
void coda_flag_inode_children(struct inode *inode, int flag)
{
struct dentry *alias_de;
if ( !inode || !S_ISDIR(inode->i_mode))
return;
alias_de = d_find_alias(inode);
if (!alias_de)
return;
coda_flag_children(alias_de, flag);
shrink_dcache_parent(alias_de);
dput(alias_de);
}
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