linux/fs/openpromfs/inode.c
Theodore Ts'o 02b9984d64 fs: push sync_filesystem() down to the file system's remount_fs()
Previously, the no-op "mount -o mount /dev/xxx" operation when the
file system is already mounted read-write causes an implied,
unconditional syncfs().  This seems pretty stupid, and it's certainly
documented or guaraunteed to do this, nor is it particularly useful,
except in the case where the file system was mounted rw and is getting
remounted read-only.

However, it's possible that there might be some file systems that are
actually depending on this behavior.  In most file systems, it's
probably fine to only call sync_filesystem() when transitioning from
read-write to read-only, and there are some file systems where this is
not needed at all (for example, for a pseudo-filesystem or something
like romfs).

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: linux-fsdevel@vger.kernel.org
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Artem Bityutskiy <dedekind1@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Evgeniy Dushistov <dushistov@mail.ru>
Cc: Jan Kara <jack@suse.cz>
Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Cc: Anders Larsen <al@alarsen.net>
Cc: Phillip Lougher <phillip@squashfs.org.uk>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Cc: Petr Vandrovec <petr@vandrovec.name>
Cc: xfs@oss.sgi.com
Cc: linux-btrfs@vger.kernel.org
Cc: linux-cifs@vger.kernel.org
Cc: samba-technical@lists.samba.org
Cc: codalist@coda.cs.cmu.edu
Cc: linux-ext4@vger.kernel.org
Cc: linux-f2fs-devel@lists.sourceforge.net
Cc: fuse-devel@lists.sourceforge.net
Cc: cluster-devel@redhat.com
Cc: linux-mtd@lists.infradead.org
Cc: jfs-discussion@lists.sourceforge.net
Cc: linux-nfs@vger.kernel.org
Cc: linux-nilfs@vger.kernel.org
Cc: linux-ntfs-dev@lists.sourceforge.net
Cc: ocfs2-devel@oss.oracle.com
Cc: reiserfs-devel@vger.kernel.org
2014-03-13 10:14:33 -04:00

472 lines
9.6 KiB
C

/* inode.c: /proc/openprom handling routines
*
* Copyright (C) 1996-1999 Jakub Jelinek (jakub@redhat.com)
* Copyright (C) 1998 Eddie C. Dost (ecd@skynet.be)
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/seq_file.h>
#include <linux/magic.h>
#include <asm/openprom.h>
#include <asm/oplib.h>
#include <asm/prom.h>
#include <asm/uaccess.h>
static DEFINE_MUTEX(op_mutex);
#define OPENPROM_ROOT_INO 0
enum op_inode_type {
op_inode_node,
op_inode_prop,
};
union op_inode_data {
struct device_node *node;
struct property *prop;
};
struct op_inode_info {
struct inode vfs_inode;
enum op_inode_type type;
union op_inode_data u;
};
static struct inode *openprom_iget(struct super_block *sb, ino_t ino);
static inline struct op_inode_info *OP_I(struct inode *inode)
{
return container_of(inode, struct op_inode_info, vfs_inode);
}
static int is_string(unsigned char *p, int len)
{
int i;
for (i = 0; i < len; i++) {
unsigned char val = p[i];
if ((i && !val) ||
(val >= ' ' && val <= '~'))
continue;
return 0;
}
return 1;
}
static int property_show(struct seq_file *f, void *v)
{
struct property *prop = f->private;
void *pval;
int len;
len = prop->length;
pval = prop->value;
if (is_string(pval, len)) {
while (len > 0) {
int n = strlen(pval);
seq_printf(f, "%s", (char *) pval);
/* Skip over the NULL byte too. */
pval += n + 1;
len -= n + 1;
if (len > 0)
seq_printf(f, " + ");
}
} else {
if (len & 3) {
while (len) {
len--;
if (len)
seq_printf(f, "%02x.",
*(unsigned char *) pval);
else
seq_printf(f, "%02x",
*(unsigned char *) pval);
pval++;
}
} else {
while (len >= 4) {
len -= 4;
if (len)
seq_printf(f, "%08x.",
*(unsigned int *) pval);
else
seq_printf(f, "%08x",
*(unsigned int *) pval);
pval += 4;
}
}
}
seq_printf(f, "\n");
return 0;
}
static void *property_start(struct seq_file *f, loff_t *pos)
{
if (*pos == 0)
return pos;
return NULL;
}
static void *property_next(struct seq_file *f, void *v, loff_t *pos)
{
(*pos)++;
return NULL;
}
static void property_stop(struct seq_file *f, void *v)
{
/* Nothing to do */
}
static const struct seq_operations property_op = {
.start = property_start,
.next = property_next,
.stop = property_stop,
.show = property_show
};
static int property_open(struct inode *inode, struct file *file)
{
struct op_inode_info *oi = OP_I(inode);
int ret;
BUG_ON(oi->type != op_inode_prop);
ret = seq_open(file, &property_op);
if (!ret) {
struct seq_file *m = file->private_data;
m->private = oi->u.prop;
}
return ret;
}
static const struct file_operations openpromfs_prop_ops = {
.open = property_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};
static int openpromfs_readdir(struct file *, struct dir_context *);
static const struct file_operations openprom_operations = {
.read = generic_read_dir,
.iterate = openpromfs_readdir,
.llseek = generic_file_llseek,
};
static struct dentry *openpromfs_lookup(struct inode *, struct dentry *, unsigned int);
static const struct inode_operations openprom_inode_operations = {
.lookup = openpromfs_lookup,
};
static struct dentry *openpromfs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
{
struct op_inode_info *ent_oi, *oi = OP_I(dir);
struct device_node *dp, *child;
struct property *prop;
enum op_inode_type ent_type;
union op_inode_data ent_data;
const char *name;
struct inode *inode;
unsigned int ino;
int len;
BUG_ON(oi->type != op_inode_node);
dp = oi->u.node;
name = dentry->d_name.name;
len = dentry->d_name.len;
mutex_lock(&op_mutex);
child = dp->child;
while (child) {
int n = strlen(child->path_component_name);
if (len == n &&
!strncmp(child->path_component_name, name, len)) {
ent_type = op_inode_node;
ent_data.node = child;
ino = child->unique_id;
goto found;
}
child = child->sibling;
}
prop = dp->properties;
while (prop) {
int n = strlen(prop->name);
if (len == n && !strncmp(prop->name, name, len)) {
ent_type = op_inode_prop;
ent_data.prop = prop;
ino = prop->unique_id;
goto found;
}
prop = prop->next;
}
mutex_unlock(&op_mutex);
return ERR_PTR(-ENOENT);
found:
inode = openprom_iget(dir->i_sb, ino);
mutex_unlock(&op_mutex);
if (IS_ERR(inode))
return ERR_CAST(inode);
ent_oi = OP_I(inode);
ent_oi->type = ent_type;
ent_oi->u = ent_data;
switch (ent_type) {
case op_inode_node:
inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
inode->i_op = &openprom_inode_operations;
inode->i_fop = &openprom_operations;
set_nlink(inode, 2);
break;
case op_inode_prop:
if (!strcmp(dp->name, "options") && (len == 17) &&
!strncmp (name, "security-password", 17))
inode->i_mode = S_IFREG | S_IRUSR | S_IWUSR;
else
inode->i_mode = S_IFREG | S_IRUGO;
inode->i_fop = &openpromfs_prop_ops;
set_nlink(inode, 1);
inode->i_size = ent_oi->u.prop->length;
break;
}
d_add(dentry, inode);
return NULL;
}
static int openpromfs_readdir(struct file *file, struct dir_context *ctx)
{
struct inode *inode = file_inode(file);
struct op_inode_info *oi = OP_I(inode);
struct device_node *dp = oi->u.node;
struct device_node *child;
struct property *prop;
int i;
mutex_lock(&op_mutex);
if (ctx->pos == 0) {
if (!dir_emit(ctx, ".", 1, inode->i_ino, DT_DIR))
goto out;
ctx->pos = 1;
}
if (ctx->pos == 1) {
if (!dir_emit(ctx, "..", 2,
(dp->parent == NULL ?
OPENPROM_ROOT_INO :
dp->parent->unique_id), DT_DIR))
goto out;
ctx->pos = 2;
}
i = ctx->pos - 2;
/* First, the children nodes as directories. */
child = dp->child;
while (i && child) {
child = child->sibling;
i--;
}
while (child) {
if (!dir_emit(ctx,
child->path_component_name,
strlen(child->path_component_name),
child->unique_id, DT_DIR))
goto out;
ctx->pos++;
child = child->sibling;
}
/* Next, the properties as files. */
prop = dp->properties;
while (i && prop) {
prop = prop->next;
i--;
}
while (prop) {
if (!dir_emit(ctx, prop->name, strlen(prop->name),
prop->unique_id, DT_REG))
goto out;
ctx->pos++;
prop = prop->next;
}
out:
mutex_unlock(&op_mutex);
return 0;
}
static struct kmem_cache *op_inode_cachep;
static struct inode *openprom_alloc_inode(struct super_block *sb)
{
struct op_inode_info *oi;
oi = kmem_cache_alloc(op_inode_cachep, GFP_KERNEL);
if (!oi)
return NULL;
return &oi->vfs_inode;
}
static void openprom_i_callback(struct rcu_head *head)
{
struct inode *inode = container_of(head, struct inode, i_rcu);
kmem_cache_free(op_inode_cachep, OP_I(inode));
}
static void openprom_destroy_inode(struct inode *inode)
{
call_rcu(&inode->i_rcu, openprom_i_callback);
}
static struct inode *openprom_iget(struct super_block *sb, ino_t ino)
{
struct inode *inode;
inode = iget_locked(sb, ino);
if (!inode)
return ERR_PTR(-ENOMEM);
if (inode->i_state & I_NEW) {
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
if (inode->i_ino == OPENPROM_ROOT_INO) {
inode->i_op = &openprom_inode_operations;
inode->i_fop = &openprom_operations;
inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
}
unlock_new_inode(inode);
}
return inode;
}
static int openprom_remount(struct super_block *sb, int *flags, char *data)
{
sync_filesystem(sb);
*flags |= MS_NOATIME;
return 0;
}
static const struct super_operations openprom_sops = {
.alloc_inode = openprom_alloc_inode,
.destroy_inode = openprom_destroy_inode,
.statfs = simple_statfs,
.remount_fs = openprom_remount,
};
static int openprom_fill_super(struct super_block *s, void *data, int silent)
{
struct inode *root_inode;
struct op_inode_info *oi;
int ret;
s->s_flags |= MS_NOATIME;
s->s_blocksize = 1024;
s->s_blocksize_bits = 10;
s->s_magic = OPENPROM_SUPER_MAGIC;
s->s_op = &openprom_sops;
s->s_time_gran = 1;
root_inode = openprom_iget(s, OPENPROM_ROOT_INO);
if (IS_ERR(root_inode)) {
ret = PTR_ERR(root_inode);
goto out_no_root;
}
oi = OP_I(root_inode);
oi->type = op_inode_node;
oi->u.node = of_find_node_by_path("/");
s->s_root = d_make_root(root_inode);
if (!s->s_root)
goto out_no_root_dentry;
return 0;
out_no_root_dentry:
ret = -ENOMEM;
out_no_root:
printk("openprom_fill_super: get root inode failed\n");
return ret;
}
static struct dentry *openprom_mount(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data)
{
return mount_single(fs_type, flags, data, openprom_fill_super);
}
static struct file_system_type openprom_fs_type = {
.owner = THIS_MODULE,
.name = "openpromfs",
.mount = openprom_mount,
.kill_sb = kill_anon_super,
};
MODULE_ALIAS_FS("openpromfs");
static void op_inode_init_once(void *data)
{
struct op_inode_info *oi = (struct op_inode_info *) data;
inode_init_once(&oi->vfs_inode);
}
static int __init init_openprom_fs(void)
{
int err;
op_inode_cachep = kmem_cache_create("op_inode_cache",
sizeof(struct op_inode_info),
0,
(SLAB_RECLAIM_ACCOUNT |
SLAB_MEM_SPREAD),
op_inode_init_once);
if (!op_inode_cachep)
return -ENOMEM;
err = register_filesystem(&openprom_fs_type);
if (err)
kmem_cache_destroy(op_inode_cachep);
return err;
}
static void __exit exit_openprom_fs(void)
{
unregister_filesystem(&openprom_fs_type);
/*
* Make sure all delayed rcu free inodes are flushed before we
* destroy cache.
*/
rcu_barrier();
kmem_cache_destroy(op_inode_cachep);
}
module_init(init_openprom_fs)
module_exit(exit_openprom_fs)
MODULE_LICENSE("GPL");