linux/fs/smbfs/inode.c

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/*
* inode.c
*
* Copyright (C) 1995, 1996 by Paal-Kr. Engstad and Volker Lendecke
* Copyright (C) 1997 by Volker Lendecke
*
* Please add a note about your changes to smbfs in the ChangeLog file.
*/
#include <linux/module.h>
#include <linux/time.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/file.h>
#include <linux/dcache.h>
#include <linux/smp_lock.h>
#include <linux/nls.h>
#include <linux/seq_file.h>
#include <linux/mount.h>
#include <linux/net.h>
#include <linux/vfs.h>
#include <linux/highuid.h>
#include <linux/sched.h>
#include <linux/smb_fs.h>
#include <linux/smbno.h>
#include <linux/smb_mount.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include "smb_debug.h"
#include "getopt.h"
#include "proto.h"
/* Always pick a default string */
#ifdef CONFIG_SMB_NLS_REMOTE
#define SMB_NLS_REMOTE CONFIG_SMB_NLS_REMOTE
#else
#define SMB_NLS_REMOTE ""
#endif
#define SMB_TTL_DEFAULT 1000
static void smb_delete_inode(struct inode *);
static void smb_put_super(struct super_block *);
static int smb_statfs(struct dentry *, struct kstatfs *);
static int smb_show_options(struct seq_file *, struct vfsmount *);
static struct kmem_cache *smb_inode_cachep;
static struct inode *smb_alloc_inode(struct super_block *sb)
{
struct smb_inode_info *ei;
ei = (struct smb_inode_info *)kmem_cache_alloc(smb_inode_cachep, GFP_KERNEL);
if (!ei)
return NULL;
return &ei->vfs_inode;
}
static void smb_destroy_inode(struct inode *inode)
{
kmem_cache_free(smb_inode_cachep, SMB_I(inode));
}
static void init_once(void *foo)
{
struct smb_inode_info *ei = (struct smb_inode_info *) foo;
inode_init_once(&ei->vfs_inode);
}
static int init_inodecache(void)
{
smb_inode_cachep = kmem_cache_create("smb_inode_cache",
sizeof(struct smb_inode_info),
0, (SLAB_RECLAIM_ACCOUNT|
SLAB_MEM_SPREAD),
init_once);
if (smb_inode_cachep == NULL)
return -ENOMEM;
return 0;
}
static void destroy_inodecache(void)
{
kmem_cache_destroy(smb_inode_cachep);
}
static int smb_remount(struct super_block *sb, int *flags, char *data)
{
*flags |= MS_NODIRATIME;
return 0;
}
static const struct super_operations smb_sops =
{
.alloc_inode = smb_alloc_inode,
.destroy_inode = smb_destroy_inode,
.drop_inode = generic_delete_inode,
.delete_inode = smb_delete_inode,
.put_super = smb_put_super,
.statfs = smb_statfs,
.show_options = smb_show_options,
.remount_fs = smb_remount,
};
/* We are always generating a new inode here */
struct inode *
smb_iget(struct super_block *sb, struct smb_fattr *fattr)
{
struct smb_sb_info *server = SMB_SB(sb);
struct inode *result;
DEBUG1("smb_iget: %p\n", fattr);
result = new_inode(sb);
if (!result)
return result;
result->i_ino = fattr->f_ino;
SMB_I(result)->open = 0;
SMB_I(result)->fileid = 0;
SMB_I(result)->access = 0;
SMB_I(result)->flags = 0;
SMB_I(result)->closed = 0;
SMB_I(result)->openers = 0;
smb_set_inode_attr(result, fattr);
if (S_ISREG(result->i_mode)) {
result->i_op = &smb_file_inode_operations;
result->i_fop = &smb_file_operations;
result->i_data.a_ops = &smb_file_aops;
} else if (S_ISDIR(result->i_mode)) {
if (server->opt.capabilities & SMB_CAP_UNIX)
result->i_op = &smb_dir_inode_operations_unix;
else
result->i_op = &smb_dir_inode_operations;
result->i_fop = &smb_dir_operations;
} else if (S_ISLNK(result->i_mode)) {
result->i_op = &smb_link_inode_operations;
} else {
init_special_inode(result, result->i_mode, fattr->f_rdev);
}
insert_inode_hash(result);
return result;
}
/*
* Copy the inode data to a smb_fattr structure.
*/
void
smb_get_inode_attr(struct inode *inode, struct smb_fattr *fattr)
{
memset(fattr, 0, sizeof(struct smb_fattr));
fattr->f_mode = inode->i_mode;
fattr->f_nlink = inode->i_nlink;
fattr->f_ino = inode->i_ino;
fattr->f_uid = inode->i_uid;
fattr->f_gid = inode->i_gid;
fattr->f_size = inode->i_size;
fattr->f_mtime = inode->i_mtime;
fattr->f_ctime = inode->i_ctime;
fattr->f_atime = inode->i_atime;
fattr->f_blocks = inode->i_blocks;
fattr->attr = SMB_I(inode)->attr;
/*
* Keep the attributes in sync with the inode permissions.
*/
if (fattr->f_mode & S_IWUSR)
fattr->attr &= ~aRONLY;
else
fattr->attr |= aRONLY;
}
/*
* Update the inode, possibly causing it to invalidate its pages if mtime/size
* is different from last time.
*/
void
smb_set_inode_attr(struct inode *inode, struct smb_fattr *fattr)
{
struct smb_inode_info *ei = SMB_I(inode);
/*
* A size change should have a different mtime, or same mtime
* but different size.
*/
time_t last_time = inode->i_mtime.tv_sec;
loff_t last_sz = inode->i_size;
inode->i_mode = fattr->f_mode;
inode->i_nlink = fattr->f_nlink;
inode->i_uid = fattr->f_uid;
inode->i_gid = fattr->f_gid;
inode->i_ctime = fattr->f_ctime;
inode->i_blocks = fattr->f_blocks;
inode->i_size = fattr->f_size;
inode->i_mtime = fattr->f_mtime;
inode->i_atime = fattr->f_atime;
ei->attr = fattr->attr;
/*
* Update the "last time refreshed" field for revalidation.
*/
ei->oldmtime = jiffies;
if (inode->i_mtime.tv_sec != last_time || inode->i_size != last_sz) {
VERBOSE("%ld changed, old=%ld, new=%ld, oz=%ld, nz=%ld\n",
inode->i_ino,
(long) last_time, (long) inode->i_mtime.tv_sec,
(long) last_sz, (long) inode->i_size);
if (!S_ISDIR(inode->i_mode))
invalidate_remote_inode(inode);
}
}
/*
* This is called if the connection has gone bad ...
* try to kill off all the current inodes.
*/
void
smb_invalidate_inodes(struct smb_sb_info *server)
{
VERBOSE("\n");
shrink_dcache_sb(SB_of(server));
invalidate_inodes(SB_of(server));
}
/*
* This is called to update the inode attributes after
* we've made changes to a file or directory.
*/
static int
smb_refresh_inode(struct dentry *dentry)
{
struct inode *inode = dentry->d_inode;
int error;
struct smb_fattr fattr;
error = smb_proc_getattr(dentry, &fattr);
if (!error) {
smb_renew_times(dentry);
/*
* Check whether the type part of the mode changed,
* and don't update the attributes if it did.
*
* And don't dick with the root inode
*/
if (inode->i_ino == 2)
return error;
if (S_ISLNK(inode->i_mode))
return error; /* VFS will deal with it */
if ((inode->i_mode & S_IFMT) == (fattr.f_mode & S_IFMT)) {
smb_set_inode_attr(inode, &fattr);
} else {
/*
* Big trouble! The inode has become a new object,
* so any operations attempted on it are invalid.
*
* To limit damage, mark the inode as bad so that
* subsequent lookup validations will fail.
*/
PARANOIA("%s/%s changed mode, %07o to %07o\n",
DENTRY_PATH(dentry),
inode->i_mode, fattr.f_mode);
fattr.f_mode = inode->i_mode; /* save mode */
make_bad_inode(inode);
inode->i_mode = fattr.f_mode; /* restore mode */
/*
* No need to worry about unhashing the dentry: the
* lookup validation will see that the inode is bad.
* But we do want to invalidate the caches ...
*/
if (!S_ISDIR(inode->i_mode))
invalidate_remote_inode(inode);
else
smb_invalid_dir_cache(inode);
error = -EIO;
}
}
return error;
}
/*
* This is called when we want to check whether the inode
* has changed on the server. If it has changed, we must
* invalidate our local caches.
*/
int
smb_revalidate_inode(struct dentry *dentry)
{
struct smb_sb_info *s = server_from_dentry(dentry);
struct inode *inode = dentry->d_inode;
int error = 0;
DEBUG1("smb_revalidate_inode\n");
lock_kernel();
/*
* Check whether we've recently refreshed the inode.
*/
if (time_before(jiffies, SMB_I(inode)->oldmtime + SMB_MAX_AGE(s))) {
VERBOSE("up-to-date, ino=%ld, jiffies=%lu, oldtime=%lu\n",
inode->i_ino, jiffies, SMB_I(inode)->oldmtime);
goto out;
}
error = smb_refresh_inode(dentry);
out:
unlock_kernel();
return error;
}
/*
* This routine is called when i_nlink == 0 and i_count goes to 0.
* All blocking cleanup operations need to go here to avoid races.
*/
static void
smb_delete_inode(struct inode *ino)
{
DEBUG1("ino=%ld\n", ino->i_ino);
truncate_inode_pages(&ino->i_data, 0);
lock_kernel();
if (smb_close(ino))
PARANOIA("could not close inode %ld\n", ino->i_ino);
unlock_kernel();
clear_inode(ino);
}
static struct option opts[] = {
{ "version", 0, 'v' },
{ "win95", SMB_MOUNT_WIN95, 1 },
{ "oldattr", SMB_MOUNT_OLDATTR, 1 },
{ "dirattr", SMB_MOUNT_DIRATTR, 1 },
{ "case", SMB_MOUNT_CASE, 1 },
{ "uid", 0, 'u' },
{ "gid", 0, 'g' },
{ "file_mode", 0, 'f' },
{ "dir_mode", 0, 'd' },
{ "iocharset", 0, 'i' },
{ "codepage", 0, 'c' },
{ "ttl", 0, 't' },
{ NULL, 0, 0}
};
static int
parse_options(struct smb_mount_data_kernel *mnt, char *options)
{
int c;
unsigned long flags;
unsigned long value;
char *optarg;
char *optopt;
flags = 0;
while ( (c = smb_getopt("smbfs", &options, opts,
&optopt, &optarg, &flags, &value)) > 0) {
VERBOSE("'%s' -> '%s'\n", optopt, optarg ? optarg : "<none>");
switch (c) {
case 1:
/* got a "flag" option */
break;
case 'v':
if (value != SMB_MOUNT_VERSION) {
printk ("smbfs: Bad mount version %ld, expected %d\n",
value, SMB_MOUNT_VERSION);
return 0;
}
mnt->version = value;
break;
case 'u':
mnt->uid = value;
flags |= SMB_MOUNT_UID;
break;
case 'g':
mnt->gid = value;
flags |= SMB_MOUNT_GID;
break;
case 'f':
mnt->file_mode = (value & S_IRWXUGO) | S_IFREG;
flags |= SMB_MOUNT_FMODE;
break;
case 'd':
mnt->dir_mode = (value & S_IRWXUGO) | S_IFDIR;
flags |= SMB_MOUNT_DMODE;
break;
case 'i':
strlcpy(mnt->codepage.local_name, optarg,
SMB_NLS_MAXNAMELEN);
break;
case 'c':
strlcpy(mnt->codepage.remote_name, optarg,
SMB_NLS_MAXNAMELEN);
break;
case 't':
mnt->ttl = value;
break;
default:
printk ("smbfs: Unrecognized mount option %s\n",
optopt);
return -1;
}
}
mnt->flags = flags;
return c;
}
/*
* smb_show_options() is for displaying mount options in /proc/mounts.
* It tries to avoid showing settings that were not changed from their
* defaults.
*/
static int
smb_show_options(struct seq_file *s, struct vfsmount *m)
{
struct smb_mount_data_kernel *mnt = SMB_SB(m->mnt_sb)->mnt;
int i;
for (i = 0; opts[i].name != NULL; i++)
if (mnt->flags & opts[i].flag)
seq_printf(s, ",%s", opts[i].name);
if (mnt->flags & SMB_MOUNT_UID)
seq_printf(s, ",uid=%d", mnt->uid);
if (mnt->flags & SMB_MOUNT_GID)
seq_printf(s, ",gid=%d", mnt->gid);
if (mnt->mounted_uid != 0)
seq_printf(s, ",mounted_uid=%d", mnt->mounted_uid);
/*
* Defaults for file_mode and dir_mode are unknown to us; they
* depend on the current umask of the user doing the mount.
*/
if (mnt->flags & SMB_MOUNT_FMODE)
seq_printf(s, ",file_mode=%04o", mnt->file_mode & S_IRWXUGO);
if (mnt->flags & SMB_MOUNT_DMODE)
seq_printf(s, ",dir_mode=%04o", mnt->dir_mode & S_IRWXUGO);
if (strcmp(mnt->codepage.local_name, CONFIG_NLS_DEFAULT))
seq_printf(s, ",iocharset=%s", mnt->codepage.local_name);
if (strcmp(mnt->codepage.remote_name, SMB_NLS_REMOTE))
seq_printf(s, ",codepage=%s", mnt->codepage.remote_name);
if (mnt->ttl != SMB_TTL_DEFAULT)
seq_printf(s, ",ttl=%d", mnt->ttl);
return 0;
}
static void
smb_unload_nls(struct smb_sb_info *server)
{
unload_nls(server->remote_nls);
unload_nls(server->local_nls);
}
static void
smb_put_super(struct super_block *sb)
{
struct smb_sb_info *server = SMB_SB(sb);
lock_kernel();
smb_lock_server(server);
server->state = CONN_INVALID;
smbiod_unregister_server(server);
smb_close_socket(server);
if (server->conn_pid)
kill_pid(server->conn_pid, SIGTERM, 1);
kfree(server->ops);
smb_unload_nls(server);
sb->s_fs_info = NULL;
smb_unlock_server(server);
put_pid(server->conn_pid);
kfree(server);
unlock_kernel();
}
static int smb_fill_super(struct super_block *sb, void *raw_data, int silent)
{
struct smb_sb_info *server;
struct smb_mount_data_kernel *mnt;
struct smb_mount_data *oldmnt;
struct inode *root_inode;
struct smb_fattr root;
int ver;
void *mem;
static int warn_count;
if (warn_count < 5) {
warn_count++;
printk(KERN_EMERG "smbfs is deprecated and will be removed"
" from the 2.6.27 kernel. Please migrate to cifs\n");
}
if (!raw_data)
goto out_no_data;
oldmnt = (struct smb_mount_data *) raw_data;
ver = oldmnt->version;
if (ver != SMB_MOUNT_OLDVERSION && cpu_to_be32(ver) != SMB_MOUNT_ASCII)
goto out_wrong_data;
sb->s_flags |= MS_NODIRATIME;
sb->s_blocksize = 1024; /* Eh... Is this correct? */
sb->s_blocksize_bits = 10;
sb->s_magic = SMB_SUPER_MAGIC;
sb->s_op = &smb_sops;
sb->s_time_gran = 100;
server = kzalloc(sizeof(struct smb_sb_info), GFP_KERNEL);
if (!server)
goto out_no_server;
sb->s_fs_info = server;
server->super_block = sb;
server->mnt = NULL;
server->sock_file = NULL;
init_waitqueue_head(&server->conn_wq);
init_MUTEX(&server->sem);
INIT_LIST_HEAD(&server->entry);
INIT_LIST_HEAD(&server->xmitq);
INIT_LIST_HEAD(&server->recvq);
server->conn_error = 0;
server->conn_pid = NULL;
server->state = CONN_INVALID; /* no connection yet */
server->generation = 0;
/* Allocate the global temp buffer and some superblock helper structs */
/* FIXME: move these to the smb_sb_info struct */
VERBOSE("alloc chunk = %lu\n", sizeof(struct smb_ops) +
sizeof(struct smb_mount_data_kernel));
mem = kmalloc(sizeof(struct smb_ops) +
sizeof(struct smb_mount_data_kernel), GFP_KERNEL);
if (!mem)
goto out_no_mem;
server->ops = mem;
smb_install_null_ops(server->ops);
server->mnt = mem + sizeof(struct smb_ops);
/* Setup NLS stuff */
server->remote_nls = NULL;
server->local_nls = NULL;
mnt = server->mnt;
memset(mnt, 0, sizeof(struct smb_mount_data_kernel));
strlcpy(mnt->codepage.local_name, CONFIG_NLS_DEFAULT,
SMB_NLS_MAXNAMELEN);
strlcpy(mnt->codepage.remote_name, SMB_NLS_REMOTE,
SMB_NLS_MAXNAMELEN);
mnt->ttl = SMB_TTL_DEFAULT;
if (ver == SMB_MOUNT_OLDVERSION) {
mnt->version = oldmnt->version;
SET_UID(mnt->uid, oldmnt->uid);
SET_GID(mnt->gid, oldmnt->gid);
mnt->file_mode = (oldmnt->file_mode & S_IRWXUGO) | S_IFREG;
mnt->dir_mode = (oldmnt->dir_mode & S_IRWXUGO) | S_IFDIR;
mnt->flags = (oldmnt->file_mode >> 9) | SMB_MOUNT_UID |
SMB_MOUNT_GID | SMB_MOUNT_FMODE | SMB_MOUNT_DMODE;
} else {
mnt->file_mode = S_IRWXU | S_IRGRP | S_IXGRP |
S_IROTH | S_IXOTH | S_IFREG;
mnt->dir_mode = S_IRWXU | S_IRGRP | S_IXGRP |
S_IROTH | S_IXOTH | S_IFDIR;
if (parse_options(mnt, raw_data))
goto out_bad_option;
}
mnt->mounted_uid = current_uid();
smb_setcodepage(server, &mnt->codepage);
/*
* Display the enabled options
* Note: smb_proc_getattr uses these in 2.4 (but was changed in 2.2)
*/
if (mnt->flags & SMB_MOUNT_OLDATTR)
printk("SMBFS: Using core getattr (Win 95 speedup)\n");
else if (mnt->flags & SMB_MOUNT_DIRATTR)
printk("SMBFS: Using dir ff getattr\n");
if (smbiod_register_server(server) < 0) {
printk(KERN_ERR "smbfs: failed to start smbiod\n");
goto out_no_smbiod;
}
/*
* Keep the super block locked while we get the root inode.
*/
smb_init_root_dirent(server, &root, sb);
root_inode = smb_iget(sb, &root);
if (!root_inode)
goto out_no_root;
sb->s_root = d_alloc_root(root_inode);
if (!sb->s_root)
goto out_no_root;
smb_new_dentry(sb->s_root);
return 0;
out_no_root:
iput(root_inode);
out_no_smbiod:
smb_unload_nls(server);
out_bad_option:
kfree(mem);
out_no_mem:
if (!server->mnt)
printk(KERN_ERR "smb_fill_super: allocation failure\n");
sb->s_fs_info = NULL;
kfree(server);
goto out_fail;
out_wrong_data:
printk(KERN_ERR "smbfs: mount_data version %d is not supported\n", ver);
goto out_fail;
out_no_data:
printk(KERN_ERR "smb_fill_super: missing data argument\n");
out_fail:
return -EINVAL;
out_no_server:
printk(KERN_ERR "smb_fill_super: cannot allocate struct smb_sb_info\n");
return -ENOMEM;
}
static int
smb_statfs(struct dentry *dentry, struct kstatfs *buf)
{
int result;
lock_kernel();
result = smb_proc_dskattr(dentry, buf);
unlock_kernel();
buf->f_type = SMB_SUPER_MAGIC;
buf->f_namelen = SMB_MAXPATHLEN;
return result;
}
int smb_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
{
int err = smb_revalidate_inode(dentry);
if (!err)
generic_fillattr(dentry->d_inode, stat);
return err;
}
int
smb_notify_change(struct dentry *dentry, struct iattr *attr)
{
struct inode *inode = dentry->d_inode;
struct smb_sb_info *server = server_from_dentry(dentry);
unsigned int mask = (S_IFREG | S_IFDIR | S_IRWXUGO);
int error, changed, refresh = 0;
struct smb_fattr fattr;
lock_kernel();
error = smb_revalidate_inode(dentry);
if (error)
goto out;
if ((error = inode_change_ok(inode, attr)) < 0)
goto out;
error = -EPERM;
if ((attr->ia_valid & ATTR_UID) && (attr->ia_uid != server->mnt->uid))
goto out;
if ((attr->ia_valid & ATTR_GID) && (attr->ia_uid != server->mnt->gid))
goto out;
if ((attr->ia_valid & ATTR_MODE) && (attr->ia_mode & ~mask))
goto out;
if ((attr->ia_valid & ATTR_SIZE) != 0) {
VERBOSE("changing %s/%s, old size=%ld, new size=%ld\n",
DENTRY_PATH(dentry),
(long) inode->i_size, (long) attr->ia_size);
filemap_write_and_wait(inode->i_mapping);
error = smb_open(dentry, O_WRONLY);
if (error)
goto out;
error = server->ops->truncate(inode, attr->ia_size);
if (error)
goto out;
error = vmtruncate(inode, attr->ia_size);
if (error)
goto out;
refresh = 1;
}
if (server->opt.capabilities & SMB_CAP_UNIX) {
/* For now we don't want to set the size with setattr_unix */
attr->ia_valid &= ~ATTR_SIZE;
/* FIXME: only call if we actually want to set something? */
error = smb_proc_setattr_unix(dentry, attr, 0, 0);
if (!error)
refresh = 1;
goto out;
}
/*
* Initialize the fattr and check for changed fields.
* Note: CTIME under SMB is creation time rather than
* change time, so we don't attempt to change it.
*/
smb_get_inode_attr(inode, &fattr);
changed = 0;
if ((attr->ia_valid & ATTR_MTIME) != 0) {
fattr.f_mtime = attr->ia_mtime;
changed = 1;
}
if ((attr->ia_valid & ATTR_ATIME) != 0) {
fattr.f_atime = attr->ia_atime;
/* Earlier protocols don't have an access time */
if (server->opt.protocol >= SMB_PROTOCOL_LANMAN2)
changed = 1;
}
if (changed) {
error = smb_proc_settime(dentry, &fattr);
if (error)
goto out;
refresh = 1;
}
/*
* Check for mode changes ... we're extremely limited in
* what can be set for SMB servers: just the read-only bit.
*/
if ((attr->ia_valid & ATTR_MODE) != 0) {
VERBOSE("%s/%s mode change, old=%x, new=%x\n",
DENTRY_PATH(dentry), fattr.f_mode, attr->ia_mode);
changed = 0;
if (attr->ia_mode & S_IWUSR) {
if (fattr.attr & aRONLY) {
fattr.attr &= ~aRONLY;
changed = 1;
}
} else {
if (!(fattr.attr & aRONLY)) {
fattr.attr |= aRONLY;
changed = 1;
}
}
if (changed) {
error = smb_proc_setattr(dentry, &fattr);
if (error)
goto out;
refresh = 1;
}
}
error = 0;
out:
if (refresh)
smb_refresh_inode(dentry);
unlock_kernel();
return error;
}
[PATCH] VFS: Permit filesystem to override root dentry on mount Extend the get_sb() filesystem operation to take an extra argument that permits the VFS to pass in the target vfsmount that defines the mountpoint. The filesystem is then required to manually set the superblock and root dentry pointers. For most filesystems, this should be done with simple_set_mnt() which will set the superblock pointer and then set the root dentry to the superblock's s_root (as per the old default behaviour). The get_sb() op now returns an integer as there's now no need to return the superblock pointer. This patch permits a superblock to be implicitly shared amongst several mount points, such as can be done with NFS to avoid potential inode aliasing. In such a case, simple_set_mnt() would not be called, and instead the mnt_root and mnt_sb would be set directly. The patch also makes the following changes: (*) the get_sb_*() convenience functions in the core kernel now take a vfsmount pointer argument and return an integer, so most filesystems have to change very little. (*) If one of the convenience function is not used, then get_sb() should normally call simple_set_mnt() to instantiate the vfsmount. This will always return 0, and so can be tail-called from get_sb(). (*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the dcache upon superblock destruction rather than shrink_dcache_anon(). This is required because the superblock may now have multiple trees that aren't actually bound to s_root, but that still need to be cleaned up. The currently called functions assume that the whole tree is rooted at s_root, and that anonymous dentries are not the roots of trees which results in dentries being left unculled. However, with the way NFS superblock sharing are currently set to be implemented, these assumptions are violated: the root of the filesystem is simply a dummy dentry and inode (the real inode for '/' may well be inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries with child trees. [*] Anonymous until discovered from another tree. (*) The documentation has been adjusted, including the additional bit of changing ext2_* into foo_* in the documentation. [akpm@osdl.org: convert ipath_fs, do other stuff] Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Cc: Nathan Scott <nathans@sgi.com> Cc: Roland Dreier <rolandd@cisco.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 09:02:57 +00:00
static int smb_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data, struct vfsmount *mnt)
{
[PATCH] VFS: Permit filesystem to override root dentry on mount Extend the get_sb() filesystem operation to take an extra argument that permits the VFS to pass in the target vfsmount that defines the mountpoint. The filesystem is then required to manually set the superblock and root dentry pointers. For most filesystems, this should be done with simple_set_mnt() which will set the superblock pointer and then set the root dentry to the superblock's s_root (as per the old default behaviour). The get_sb() op now returns an integer as there's now no need to return the superblock pointer. This patch permits a superblock to be implicitly shared amongst several mount points, such as can be done with NFS to avoid potential inode aliasing. In such a case, simple_set_mnt() would not be called, and instead the mnt_root and mnt_sb would be set directly. The patch also makes the following changes: (*) the get_sb_*() convenience functions in the core kernel now take a vfsmount pointer argument and return an integer, so most filesystems have to change very little. (*) If one of the convenience function is not used, then get_sb() should normally call simple_set_mnt() to instantiate the vfsmount. This will always return 0, and so can be tail-called from get_sb(). (*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the dcache upon superblock destruction rather than shrink_dcache_anon(). This is required because the superblock may now have multiple trees that aren't actually bound to s_root, but that still need to be cleaned up. The currently called functions assume that the whole tree is rooted at s_root, and that anonymous dentries are not the roots of trees which results in dentries being left unculled. However, with the way NFS superblock sharing are currently set to be implemented, these assumptions are violated: the root of the filesystem is simply a dummy dentry and inode (the real inode for '/' may well be inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries with child trees. [*] Anonymous until discovered from another tree. (*) The documentation has been adjusted, including the additional bit of changing ext2_* into foo_* in the documentation. [akpm@osdl.org: convert ipath_fs, do other stuff] Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Cc: Nathan Scott <nathans@sgi.com> Cc: Roland Dreier <rolandd@cisco.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 09:02:57 +00:00
return get_sb_nodev(fs_type, flags, data, smb_fill_super, mnt);
}
static struct file_system_type smb_fs_type = {
.owner = THIS_MODULE,
.name = "smbfs",
.get_sb = smb_get_sb,
.kill_sb = kill_anon_super,
.fs_flags = FS_BINARY_MOUNTDATA,
};
static int __init init_smb_fs(void)
{
int err;
DEBUG1("registering ...\n");
err = init_inodecache();
if (err)
goto out_inode;
err = smb_init_request_cache();
if (err)
goto out_request;
err = register_filesystem(&smb_fs_type);
if (err)
goto out;
return 0;
out:
smb_destroy_request_cache();
out_request:
destroy_inodecache();
out_inode:
return err;
}
static void __exit exit_smb_fs(void)
{
DEBUG1("unregistering ...\n");
unregister_filesystem(&smb_fs_type);
smb_destroy_request_cache();
destroy_inodecache();
}
module_init(init_smb_fs)
module_exit(exit_smb_fs)
MODULE_LICENSE("GPL");