/*
 * 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 */
};

static const struct inode_operations afs_symlink_inode_operations = {
        .get_link       = page_get_link,
        .listxattr      = afs_listxattr,
};

/*
 * 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:
                /* Symlinks with a mode of 0644 are actually mountpoints. */
                if ((vnode->status.mode & 0777) == 0644) {
                        inode->i_flags |= S_AUTOMOUNT;

                        spin_lock(&vnode->lock);
                        set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
                        spin_unlock(&vnode->lock);

                        inode->i_mode   = S_IFDIR | 0555;
                        inode->i_op     = &afs_mntpt_inode_operations;
                        inode->i_fop    = &afs_mntpt_file_operations;
                } else {
                        inode->i_mode   = S_IFLNK | vnode->status.mode;
                        inode->i_op     = &afs_symlink_inode_operations;
                }
                inode_nohighmem(inode);
                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

        set_nlink(inode, vnode->status.nlink);
        inode->i_uid            = vnode->status.owner;
        inode->i_gid            = vnode->status.group;
        inode->i_size           = vnode->status.size;
        inode->i_ctime.tv_sec   = vnode->status.mtime_client;
        inode->i_ctime.tv_nsec  = 0;
        inode->i_atime          = inode->i_mtime = inode->i_ctime;
        inode->i_blocks         = 0;
        inode->i_generation     = vnode->fid.unique;
        inode->i_version        = vnode->status.data_version;
        inode->i_mapping->a_ops = &afs_fs_aops;
        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_generation == 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_generation = 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;
        set_nlink(inode, 2);
        inode->i_uid            = GLOBAL_ROOT_UID;
        inode->i_gid            = GLOBAL_ROOT_GID;
        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);
        set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
        inode->i_flags |= S_AUTOMOUNT | 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 = ktime_get_real_seconds();
                } else {
                        vnode->cb_version = cb->version;
                        vnode->cb_expiry = cb->expiry;
                        vnode->cb_type = cb->type;
                        vnode->cb_expires = vnode->cb_expiry +
                                ktime_get_real_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, true);
#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 < ktime_get_real_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(const struct path *path, struct kstat *stat,
                u32 request_mask, unsigned int query_flags)
{
        struct inode *inode = d_inode(path->dentry);

        _enter("{ ino=%lu v=%u }", inode->i_ino, inode->i_generation);

        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_final(&inode->i_data);
        clear_inode(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_INIT_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(d_inode(dentry));
        struct key *key;
        int ret;

        _enter("{%x:%u},{n=%pd},%x",
               vnode->fid.vid, vnode->fid.vnode, dentry,
               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;
}