linux/fs/afs/inode.c
wanglei bec5eb6141 AFS: Implement an autocell mount capability [ver #2]
Implement the ability for the root directory of a mounted AFS filesystem to
accept lookups of arbitrary directory names, to interpet the names as the names
of cells, to look the cell names up in the DNS for AFSDB records and to mount
the root.cell volume of the nominated cell on the pseudo-directory created by
lookup.

This facility is requested by passing:

	-o autocell

to the mountpoint for which this is desired, usually the /afs mount.

To use this facility, a DNS upcall program is required for AFSDB records.  This
can be obtained from:

	http://people.redhat.com/~dhowells/afs/dns.afsdb.c

It should be compiled with -lresolv and -lkeyutils and installed as, say:

	/usr/sbin/dns.afsdb

Then the following line needs to be added to /sbin/request-key.conf:

	create	dns_resolver afsdb:*	*	/usr/sbin/dns.afsdb %k

This can be tested by mounting AFS, say:

	insmod dns_resolver.ko
	insmod af-rxrpc.ko
	insmod kafs.ko rootcell=grand.central.org
	mount -t afs "#grand.central.org:root.cell." /afs -o autocell

and doing:

	ls /afs/grand.central.org/

which should show:

	archive/  cvs/  doc/  local/  project/  service/  software/  user/  www/

if it works.

Signed-off-by: Wang Lei <wang840925@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
2010-08-11 17:11:29 +00:00

498 lines
12 KiB
C

/*
* Copyright (c) 2002 Red Hat, Inc. All rights reserved.
*
* This software may be freely redistributed under the terms of the
* GNU General Public License.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* Authors: David Woodhouse <dwmw2@infradead.org>
* David Howells <dhowells@redhat.com>
*
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/sched.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include "internal.h"
struct afs_iget_data {
struct afs_fid fid;
struct afs_volume *volume; /* volume on which resides */
};
/*
* map the AFS file status to the inode member variables
*/
static int afs_inode_map_status(struct afs_vnode *vnode, struct key *key)
{
struct inode *inode = AFS_VNODE_TO_I(vnode);
_debug("FS: ft=%d lk=%d sz=%llu ver=%Lu mod=%hu",
vnode->status.type,
vnode->status.nlink,
(unsigned long long) vnode->status.size,
vnode->status.data_version,
vnode->status.mode);
switch (vnode->status.type) {
case AFS_FTYPE_FILE:
inode->i_mode = S_IFREG | vnode->status.mode;
inode->i_op = &afs_file_inode_operations;
inode->i_fop = &afs_file_operations;
break;
case AFS_FTYPE_DIR:
inode->i_mode = S_IFDIR | vnode->status.mode;
inode->i_op = &afs_dir_inode_operations;
inode->i_fop = &afs_dir_file_operations;
break;
case AFS_FTYPE_SYMLINK:
inode->i_mode = S_IFLNK | vnode->status.mode;
inode->i_op = &page_symlink_inode_operations;
break;
default:
printk("kAFS: AFS vnode with undefined type\n");
return -EBADMSG;
}
#ifdef CONFIG_AFS_FSCACHE
if (vnode->status.size != inode->i_size)
fscache_attr_changed(vnode->cache);
#endif
inode->i_nlink = vnode->status.nlink;
inode->i_uid = vnode->status.owner;
inode->i_gid = 0;
inode->i_size = vnode->status.size;
inode->i_ctime.tv_sec = vnode->status.mtime_server;
inode->i_ctime.tv_nsec = 0;
inode->i_atime = inode->i_mtime = inode->i_ctime;
inode->i_blocks = 0;
inode->i_version = vnode->fid.unique;
inode->i_mapping->a_ops = &afs_fs_aops;
/* check to see whether a symbolic link is really a mountpoint */
if (vnode->status.type == AFS_FTYPE_SYMLINK) {
afs_mntpt_check_symlink(vnode, key);
if (test_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags)) {
inode->i_mode = S_IFDIR | vnode->status.mode;
inode->i_op = &afs_mntpt_inode_operations;
inode->i_fop = &afs_mntpt_file_operations;
}
}
return 0;
}
/*
* iget5() comparator
*/
static int afs_iget5_test(struct inode *inode, void *opaque)
{
struct afs_iget_data *data = opaque;
return inode->i_ino == data->fid.vnode &&
inode->i_version == data->fid.unique;
}
/*
* iget5() comparator for inode created by autocell operations
*
* These pseudo inodes don't match anything.
*/
static int afs_iget5_autocell_test(struct inode *inode, void *opaque)
{
return 0;
}
/*
* iget5() inode initialiser
*/
static int afs_iget5_set(struct inode *inode, void *opaque)
{
struct afs_iget_data *data = opaque;
struct afs_vnode *vnode = AFS_FS_I(inode);
inode->i_ino = data->fid.vnode;
inode->i_version = data->fid.unique;
vnode->fid = data->fid;
vnode->volume = data->volume;
return 0;
}
/*
* inode retrieval for autocell
*/
struct inode *afs_iget_autocell(struct inode *dir, const char *dev_name,
int namesz, struct key *key)
{
struct afs_iget_data data;
struct afs_super_info *as;
struct afs_vnode *vnode;
struct super_block *sb;
struct inode *inode;
static atomic_t afs_autocell_ino;
_enter("{%x:%u},%*.*s,",
AFS_FS_I(dir)->fid.vid, AFS_FS_I(dir)->fid.vnode,
namesz, namesz, dev_name ?: "");
sb = dir->i_sb;
as = sb->s_fs_info;
data.volume = as->volume;
data.fid.vid = as->volume->vid;
data.fid.unique = 0;
data.fid.vnode = 0;
inode = iget5_locked(sb, atomic_inc_return(&afs_autocell_ino),
afs_iget5_autocell_test, afs_iget5_set,
&data);
if (!inode) {
_leave(" = -ENOMEM");
return ERR_PTR(-ENOMEM);
}
_debug("GOT INODE %p { ino=%lu, vl=%x, vn=%x, u=%x }",
inode, inode->i_ino, data.fid.vid, data.fid.vnode,
data.fid.unique);
vnode = AFS_FS_I(inode);
/* there shouldn't be an existing inode */
BUG_ON(!(inode->i_state & I_NEW));
inode->i_size = 0;
inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO;
inode->i_op = &afs_autocell_inode_operations;
inode->i_nlink = 2;
inode->i_uid = 0;
inode->i_gid = 0;
inode->i_ctime.tv_sec = get_seconds();
inode->i_ctime.tv_nsec = 0;
inode->i_atime = inode->i_mtime = inode->i_ctime;
inode->i_blocks = 0;
inode->i_version = 0;
inode->i_generation = 0;
set_bit(AFS_VNODE_PSEUDODIR, &vnode->flags);
inode->i_flags |= S_NOATIME;
unlock_new_inode(inode);
_leave(" = %p", inode);
return inode;
}
/*
* inode retrieval
*/
struct inode *afs_iget(struct super_block *sb, struct key *key,
struct afs_fid *fid, struct afs_file_status *status,
struct afs_callback *cb)
{
struct afs_iget_data data = { .fid = *fid };
struct afs_super_info *as;
struct afs_vnode *vnode;
struct inode *inode;
int ret;
_enter(",{%x:%u.%u},,", fid->vid, fid->vnode, fid->unique);
as = sb->s_fs_info;
data.volume = as->volume;
inode = iget5_locked(sb, fid->vnode, afs_iget5_test, afs_iget5_set,
&data);
if (!inode) {
_leave(" = -ENOMEM");
return ERR_PTR(-ENOMEM);
}
_debug("GOT INODE %p { vl=%x vn=%x, u=%x }",
inode, fid->vid, fid->vnode, fid->unique);
vnode = AFS_FS_I(inode);
/* deal with an existing inode */
if (!(inode->i_state & I_NEW)) {
_leave(" = %p", inode);
return inode;
}
if (!status) {
/* it's a remotely extant inode */
set_bit(AFS_VNODE_CB_BROKEN, &vnode->flags);
ret = afs_vnode_fetch_status(vnode, NULL, key);
if (ret < 0)
goto bad_inode;
} else {
/* it's an inode we just created */
memcpy(&vnode->status, status, sizeof(vnode->status));
if (!cb) {
/* it's a symlink we just created (the fileserver
* didn't give us a callback) */
vnode->cb_version = 0;
vnode->cb_expiry = 0;
vnode->cb_type = 0;
vnode->cb_expires = get_seconds();
} else {
vnode->cb_version = cb->version;
vnode->cb_expiry = cb->expiry;
vnode->cb_type = cb->type;
vnode->cb_expires = vnode->cb_expiry + get_seconds();
}
}
/* set up caching before mapping the status, as map-status reads the
* first page of symlinks to see if they're really mountpoints */
inode->i_size = vnode->status.size;
#ifdef CONFIG_AFS_FSCACHE
vnode->cache = fscache_acquire_cookie(vnode->volume->cache,
&afs_vnode_cache_index_def,
vnode);
#endif
ret = afs_inode_map_status(vnode, key);
if (ret < 0)
goto bad_inode;
/* success */
clear_bit(AFS_VNODE_UNSET, &vnode->flags);
inode->i_flags |= S_NOATIME;
unlock_new_inode(inode);
_leave(" = %p [CB { v=%u t=%u }]", inode, vnode->cb_version, vnode->cb_type);
return inode;
/* failure */
bad_inode:
#ifdef CONFIG_AFS_FSCACHE
fscache_relinquish_cookie(vnode->cache, 0);
vnode->cache = NULL;
#endif
iget_failed(inode);
_leave(" = %d [bad]", ret);
return ERR_PTR(ret);
}
/*
* mark the data attached to an inode as obsolete due to a write on the server
* - might also want to ditch all the outstanding writes and dirty pages
*/
void afs_zap_data(struct afs_vnode *vnode)
{
_enter("{%x:%u}", vnode->fid.vid, vnode->fid.vnode);
/* nuke all the non-dirty pages that aren't locked, mapped or being
* written back in a regular file and completely discard the pages in a
* directory or symlink */
if (S_ISREG(vnode->vfs_inode.i_mode))
invalidate_remote_inode(&vnode->vfs_inode);
else
invalidate_inode_pages2(vnode->vfs_inode.i_mapping);
}
/*
* validate a vnode/inode
* - there are several things we need to check
* - parent dir data changes (rm, rmdir, rename, mkdir, create, link,
* symlink)
* - parent dir metadata changed (security changes)
* - dentry data changed (write, truncate)
* - dentry metadata changed (security changes)
*/
int afs_validate(struct afs_vnode *vnode, struct key *key)
{
int ret;
_enter("{v={%x:%u} fl=%lx},%x",
vnode->fid.vid, vnode->fid.vnode, vnode->flags,
key_serial(key));
if (vnode->cb_promised &&
!test_bit(AFS_VNODE_CB_BROKEN, &vnode->flags) &&
!test_bit(AFS_VNODE_MODIFIED, &vnode->flags) &&
!test_bit(AFS_VNODE_ZAP_DATA, &vnode->flags)) {
if (vnode->cb_expires < get_seconds() + 10) {
_debug("callback expired");
set_bit(AFS_VNODE_CB_BROKEN, &vnode->flags);
} else {
goto valid;
}
}
if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
goto valid;
mutex_lock(&vnode->validate_lock);
/* if the promise has expired, we need to check the server again to get
* a new promise - note that if the (parent) directory's metadata was
* changed then the security may be different and we may no longer have
* access */
if (!vnode->cb_promised ||
test_bit(AFS_VNODE_CB_BROKEN, &vnode->flags)) {
_debug("not promised");
ret = afs_vnode_fetch_status(vnode, NULL, key);
if (ret < 0)
goto error_unlock;
_debug("new promise [fl=%lx]", vnode->flags);
}
if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) {
_debug("file already deleted");
ret = -ESTALE;
goto error_unlock;
}
/* if the vnode's data version number changed then its contents are
* different */
if (test_and_clear_bit(AFS_VNODE_ZAP_DATA, &vnode->flags))
afs_zap_data(vnode);
clear_bit(AFS_VNODE_MODIFIED, &vnode->flags);
mutex_unlock(&vnode->validate_lock);
valid:
_leave(" = 0");
return 0;
error_unlock:
mutex_unlock(&vnode->validate_lock);
_leave(" = %d", ret);
return ret;
}
/*
* read the attributes of an inode
*/
int afs_getattr(struct vfsmount *mnt, struct dentry *dentry,
struct kstat *stat)
{
struct inode *inode;
inode = dentry->d_inode;
_enter("{ ino=%lu v=%llu }", inode->i_ino,
(unsigned long long)inode->i_version);
generic_fillattr(inode, stat);
return 0;
}
/*
* discard an AFS inode
*/
int afs_drop_inode(struct inode *inode)
{
_enter("");
if (test_bit(AFS_VNODE_PSEUDODIR, &AFS_FS_I(inode)->flags))
return generic_delete_inode(inode);
else
return generic_drop_inode(inode);
}
/*
* clear an AFS inode
*/
void afs_evict_inode(struct inode *inode)
{
struct afs_permits *permits;
struct afs_vnode *vnode;
vnode = AFS_FS_I(inode);
_enter("{%x:%u.%d} v=%u x=%u t=%u }",
vnode->fid.vid,
vnode->fid.vnode,
vnode->fid.unique,
vnode->cb_version,
vnode->cb_expiry,
vnode->cb_type);
_debug("CLEAR INODE %p", inode);
ASSERTCMP(inode->i_ino, ==, vnode->fid.vnode);
truncate_inode_pages(&inode->i_data, 0);
end_writeback(inode);
afs_give_up_callback(vnode);
if (vnode->server) {
spin_lock(&vnode->server->fs_lock);
rb_erase(&vnode->server_rb, &vnode->server->fs_vnodes);
spin_unlock(&vnode->server->fs_lock);
afs_put_server(vnode->server);
vnode->server = NULL;
}
ASSERT(list_empty(&vnode->writebacks));
ASSERT(!vnode->cb_promised);
#ifdef CONFIG_AFS_FSCACHE
fscache_relinquish_cookie(vnode->cache, 0);
vnode->cache = NULL;
#endif
mutex_lock(&vnode->permits_lock);
permits = vnode->permits;
rcu_assign_pointer(vnode->permits, NULL);
mutex_unlock(&vnode->permits_lock);
if (permits)
call_rcu(&permits->rcu, afs_zap_permits);
_leave("");
}
/*
* set the attributes of an inode
*/
int afs_setattr(struct dentry *dentry, struct iattr *attr)
{
struct afs_vnode *vnode = AFS_FS_I(dentry->d_inode);
struct key *key;
int ret;
_enter("{%x:%u},{n=%s},%x",
vnode->fid.vid, vnode->fid.vnode, dentry->d_name.name,
attr->ia_valid);
if (!(attr->ia_valid & (ATTR_SIZE | ATTR_MODE | ATTR_UID | ATTR_GID |
ATTR_MTIME))) {
_leave(" = 0 [unsupported]");
return 0;
}
/* flush any dirty data outstanding on a regular file */
if (S_ISREG(vnode->vfs_inode.i_mode)) {
filemap_write_and_wait(vnode->vfs_inode.i_mapping);
afs_writeback_all(vnode);
}
if (attr->ia_valid & ATTR_FILE) {
key = attr->ia_file->private_data;
} else {
key = afs_request_key(vnode->volume->cell);
if (IS_ERR(key)) {
ret = PTR_ERR(key);
goto error;
}
}
ret = afs_vnode_setattr(vnode, key, attr);
if (!(attr->ia_valid & ATTR_FILE))
key_put(key);
error:
_leave(" = %d", ret);
return ret;
}