/*
 * 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 <linux/iversion.h>
#include "internal.h"
#include "afs_fs.h"

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

static noinline void dump_vnode(struct afs_vnode *vnode, struct afs_vnode *parent_vnode)
{
        static unsigned long once_only;

        pr_warn("kAFS: AFS vnode with undefined type %u\n", vnode->status.type);
        pr_warn("kAFS: A=%d m=%o s=%llx v=%llx\n",
                vnode->status.abort_code,
                vnode->status.mode,
                vnode->status.size,
                vnode->status.data_version);
        pr_warn("kAFS: vnode %llx:%llx:%x\n",
                vnode->fid.vid,
                vnode->fid.vnode,
                vnode->fid.unique);
        if (parent_vnode)
                pr_warn("kAFS: dir %llx:%llx:%x\n",
                        parent_vnode->fid.vid,
                        parent_vnode->fid.vnode,
                        parent_vnode->fid.unique);

        if (!test_and_set_bit(0, &once_only))
                dump_stack();
}

/*
 * Set the file size and block count.  Estimate the number of 512 bytes blocks
 * used, rounded up to nearest 1K for consistency with other AFS clients.
 */
static void afs_set_i_size(struct afs_vnode *vnode, u64 size)
{
        i_size_write(&vnode->vfs_inode, size);
        vnode->vfs_inode.i_blocks = ((size + 1023) >> 10) << 1;
}

/*
 * Initialise an inode from the vnode status.
 */
static int afs_inode_init_from_status(struct afs_vnode *vnode, struct key *key,
                                      struct afs_cb_interest *cbi,
                                      struct afs_vnode *parent_vnode,
                                      struct afs_status_cb *scb)
{
        struct afs_cb_interest *old_cbi = NULL;
        struct afs_file_status *status = &scb->status;
        struct inode *inode = AFS_VNODE_TO_I(vnode);
        struct timespec64 t;

        _debug("FS: ft=%d lk=%d sz=%llu ver=%Lu mod=%hu",
               status->type,
               status->nlink,
               (unsigned long long) status->size,
               status->data_version,
               status->mode);

        write_seqlock(&vnode->cb_lock);

        vnode->status = *status;

        t = status->mtime_client;
        inode->i_ctime = t;
        inode->i_mtime = t;
        inode->i_atime = t;
        inode->i_uid = make_kuid(&init_user_ns, status->owner);
        inode->i_gid = make_kgid(&init_user_ns, status->group);
        set_nlink(&vnode->vfs_inode, status->nlink);

        switch (status->type) {
        case AFS_FTYPE_FILE:
                inode->i_mode   = S_IFREG | status->mode;
                inode->i_op     = &afs_file_inode_operations;
                inode->i_fop    = &afs_file_operations;
                inode->i_mapping->a_ops = &afs_fs_aops;
                break;
        case AFS_FTYPE_DIR:
                inode->i_mode   = S_IFDIR | status->mode;
                inode->i_op     = &afs_dir_inode_operations;
                inode->i_fop    = &afs_dir_file_operations;
                inode->i_mapping->a_ops = &afs_dir_aops;
                break;
        case AFS_FTYPE_SYMLINK:
                /* Symlinks with a mode of 0644 are actually mountpoints. */
                if ((status->mode & 0777) == 0644) {
                        inode->i_flags |= S_AUTOMOUNT;

                        set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);

                        inode->i_mode   = S_IFDIR | 0555;
                        inode->i_op     = &afs_mntpt_inode_operations;
                        inode->i_fop    = &afs_mntpt_file_operations;
                        inode->i_mapping->a_ops = &afs_fs_aops;
                } else {
                        inode->i_mode   = S_IFLNK | status->mode;
                        inode->i_op     = &afs_symlink_inode_operations;
                        inode->i_mapping->a_ops = &afs_fs_aops;
                }
                inode_nohighmem(inode);
                break;
        default:
                dump_vnode(vnode, parent_vnode);
                write_sequnlock(&vnode->cb_lock);
                return afs_protocol_error(NULL, -EBADMSG, afs_eproto_file_type);
        }

        afs_set_i_size(vnode, status->size);

        vnode->invalid_before   = status->data_version;
        inode_set_iversion_raw(&vnode->vfs_inode, status->data_version);

        if (!scb->have_cb) {
                /* it's a symlink we just created (the fileserver
                 * didn't give us a callback) */
                vnode->cb_expires_at = ktime_get_real_seconds();
        } else {
                vnode->cb_expires_at = scb->callback.expires_at;
                old_cbi = rcu_dereference_protected(vnode->cb_interest,
                                                    lockdep_is_held(&vnode->cb_lock.lock));
                if (cbi != old_cbi)
                        rcu_assign_pointer(vnode->cb_interest, afs_get_cb_interest(cbi));
                else
                        old_cbi = NULL;
                set_bit(AFS_VNODE_CB_PROMISED, &vnode->flags);
        }

        write_sequnlock(&vnode->cb_lock);
        afs_put_cb_interest(afs_v2net(vnode), old_cbi);
        return 0;
}

/*
 * Update the core inode struct from a returned status record.
 */
static void afs_apply_status(struct afs_fs_cursor *fc,
                             struct afs_vnode *vnode,
                             struct afs_status_cb *scb,
                             const afs_dataversion_t *expected_version)
{
        struct afs_file_status *status = &scb->status;
        struct timespec64 t;
        umode_t mode;
        bool data_changed = false;

        BUG_ON(test_bit(AFS_VNODE_UNSET, &vnode->flags));

        if (status->type != vnode->status.type) {
                pr_warn("Vnode %llx:%llx:%x changed type %u to %u\n",
                        vnode->fid.vid,
                        vnode->fid.vnode,
                        vnode->fid.unique,
                        status->type, vnode->status.type);
                afs_protocol_error(NULL, -EBADMSG, afs_eproto_bad_status);
                return;
        }

        if (status->nlink != vnode->status.nlink)
                set_nlink(&vnode->vfs_inode, status->nlink);

        if (status->owner != vnode->status.owner)
                vnode->vfs_inode.i_uid = make_kuid(&init_user_ns, status->owner);

        if (status->group != vnode->status.group)
                vnode->vfs_inode.i_gid = make_kgid(&init_user_ns, status->group);

        if (status->mode != vnode->status.mode) {
                mode = vnode->vfs_inode.i_mode;
                mode &= ~S_IALLUGO;
                mode |= status->mode;
                WRITE_ONCE(vnode->vfs_inode.i_mode, mode);
        }

        t = status->mtime_client;
        vnode->vfs_inode.i_ctime = t;
        vnode->vfs_inode.i_mtime = t;
        vnode->vfs_inode.i_atime = t;

        if (vnode->status.data_version != status->data_version)
                data_changed = true;

        vnode->status = *status;

        if (expected_version &&
            *expected_version != status->data_version) {
                if (test_bit(AFS_VNODE_CB_PROMISED, &vnode->flags))
                        pr_warn("kAFS: vnode modified {%llx:%llu} %llx->%llx %s\n",
                                vnode->fid.vid, vnode->fid.vnode,
                                (unsigned long long)*expected_version,
                                (unsigned long long)status->data_version,
                                fc->type ? fc->type->name : "???");

                vnode->invalid_before = status->data_version;
                if (vnode->status.type == AFS_FTYPE_DIR) {
                        if (test_and_clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags))
                                afs_stat_v(vnode, n_inval);
                } else {
                        set_bit(AFS_VNODE_ZAP_DATA, &vnode->flags);
                }
        } else if (vnode->status.type == AFS_FTYPE_DIR) {
                /* Expected directory change is handled elsewhere so
                 * that we can locally edit the directory and save on a
                 * download.
                 */
                if (test_bit(AFS_VNODE_DIR_VALID, &vnode->flags))
                        data_changed = false;
        }

        if (data_changed) {
                inode_set_iversion_raw(&vnode->vfs_inode, status->data_version);
                afs_set_i_size(vnode, status->size);
        }
}

/*
 * Apply a callback to a vnode.
 */
static void afs_apply_callback(struct afs_fs_cursor *fc,
                               struct afs_vnode *vnode,
                               struct afs_status_cb *scb,
                               unsigned int cb_break)
{
        struct afs_cb_interest *old;
        struct afs_callback *cb = &scb->callback;

        if (!afs_cb_is_broken(cb_break, vnode, fc->cbi)) {
                vnode->cb_expires_at    = cb->expires_at;
                old = rcu_dereference_protected(vnode->cb_interest,
                                                lockdep_is_held(&vnode->cb_lock.lock));
                if (old != fc->cbi) {
                        rcu_assign_pointer(vnode->cb_interest, afs_get_cb_interest(fc->cbi));
                        afs_put_cb_interest(afs_v2net(vnode), old);
                }
                set_bit(AFS_VNODE_CB_PROMISED, &vnode->flags);
        }
}

/*
 * Apply the received status and callback to an inode all in the same critical
 * section to avoid races with afs_validate().
 */
void afs_vnode_commit_status(struct afs_fs_cursor *fc,
                             struct afs_vnode *vnode,
                             unsigned int cb_break,
                             const afs_dataversion_t *expected_version,
                             struct afs_status_cb *scb)
{
        if (fc->ac.error != 0)
                return;

        write_seqlock(&vnode->cb_lock);

        if (scb->have_error) {
                if (scb->status.abort_code == VNOVNODE) {
                        set_bit(AFS_VNODE_DELETED, &vnode->flags);
                        clear_nlink(&vnode->vfs_inode);
                        __afs_break_callback(vnode, afs_cb_break_for_deleted);
                }
        } else {
                if (scb->have_status)
                        afs_apply_status(fc, vnode, scb, expected_version);
                if (scb->have_cb)
                        afs_apply_callback(fc, vnode, scb, cb_break);
        }

        write_sequnlock(&vnode->cb_lock);

        if (fc->ac.error == 0 && scb->have_status)
                afs_cache_permit(vnode, fc->key, cb_break, scb);
}

/*
 * Fetch file status from the volume.
 */
int afs_fetch_status(struct afs_vnode *vnode, struct key *key, bool is_new,
                     afs_access_t *_caller_access)
{
        struct afs_status_cb *scb;
        struct afs_fs_cursor fc;
        int ret;

        _enter("%s,{%llx:%llu.%u,S=%lx}",
               vnode->volume->name,
               vnode->fid.vid, vnode->fid.vnode, vnode->fid.unique,
               vnode->flags);

        scb = kzalloc(sizeof(struct afs_status_cb), GFP_KERNEL);
        if (!scb)
                return -ENOMEM;

        ret = -ERESTARTSYS;
        if (afs_begin_vnode_operation(&fc, vnode, key, true)) {
                afs_dataversion_t data_version = vnode->status.data_version;

                while (afs_select_fileserver(&fc)) {
                        fc.cb_break = afs_calc_vnode_cb_break(vnode);
                        afs_fs_fetch_file_status(&fc, scb, NULL);
                }

                if (fc.error) {
                        /* Do nothing. */
                } else if (is_new) {
                        ret = afs_inode_init_from_status(vnode, key, fc.cbi,
                                                         NULL, scb);
                        fc.error = ret;
                        if (ret == 0)
                                afs_cache_permit(vnode, key, fc.cb_break, scb);
                } else {
                        afs_vnode_commit_status(&fc, vnode, fc.cb_break,
                                                &data_version, scb);
                }
                afs_check_for_remote_deletion(&fc, vnode);
                ret = afs_end_vnode_operation(&fc);
        }

        if (ret == 0 && _caller_access)
                *_caller_access = scb->status.caller_access;
        kfree(scb);
        _leave(" = %d", ret);
        return ret;
}

/*
 * iget5() comparator
 */
int afs_iget5_test(struct inode *inode, void *opaque)
{
        struct afs_iget_data *iget_data = opaque;
        struct afs_vnode *vnode = AFS_FS_I(inode);

        return memcmp(&vnode->fid, &iget_data->fid, sizeof(iget_data->fid)) == 0;
}

/*
 * iget5() comparator for inode created by autocell operations
 *
 * These pseudo inodes don't match anything.
 */
static int afs_iget5_pseudo_dir_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 *iget_data = opaque;
        struct afs_vnode *vnode = AFS_FS_I(inode);

        vnode->fid              = iget_data->fid;
        vnode->volume           = iget_data->volume;
        vnode->cb_v_break       = iget_data->cb_v_break;
        vnode->cb_s_break       = iget_data->cb_s_break;

        /* YFS supports 96-bit vnode IDs, but Linux only supports
         * 64-bit inode numbers.
         */
        inode->i_ino            = iget_data->fid.vnode;
        inode->i_generation     = iget_data->fid.unique;
        return 0;
}

/*
 * Create an inode for a dynamic root directory or an autocell dynamic
 * automount dir.
 */
struct inode *afs_iget_pseudo_dir(struct super_block *sb, bool root)
{
        struct afs_super_info *as;
        struct afs_vnode *vnode;
        struct inode *inode;
        static atomic_t afs_autocell_ino;

        struct afs_iget_data iget_data = {
                .cb_v_break = 0,
                .cb_s_break = 0,
        };

        _enter("");

        as = sb->s_fs_info;
        if (as->volume) {
                iget_data.volume = as->volume;
                iget_data.fid.vid = as->volume->vid;
        }
        if (root) {
                iget_data.fid.vnode = 1;
                iget_data.fid.unique = 1;
        } else {
                iget_data.fid.vnode = atomic_inc_return(&afs_autocell_ino);
                iget_data.fid.unique = 0;
        }

        inode = iget5_locked(sb, iget_data.fid.vnode,
                             afs_iget5_pseudo_dir_test, afs_iget5_set,
                             &iget_data);
        if (!inode) {
                _leave(" = -ENOMEM");
                return ERR_PTR(-ENOMEM);
        }

        _debug("GOT INODE %p { ino=%lu, vl=%llx, vn=%llx, u=%x }",
               inode, inode->i_ino, iget_data.fid.vid, iget_data.fid.vnode,
               iget_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;
        if (root) {
                inode->i_op     = &afs_dynroot_inode_operations;
                inode->i_fop    = &simple_dir_operations;
        } else {
                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 = inode->i_atime = inode->i_mtime = current_time(inode);
        inode->i_blocks         = 0;
        inode_set_iversion_raw(inode, 0);
        inode->i_generation     = 0;

        set_bit(AFS_VNODE_PSEUDODIR, &vnode->flags);
        if (!root) {
                set_bit(AFS_VNODE_MOUNTPOINT, &vnode->flags);
                inode->i_flags |= S_AUTOMOUNT;
        }

        inode->i_flags |= S_NOATIME;
        unlock_new_inode(inode);
        _leave(" = %p", inode);
        return inode;
}

/*
 * Get a cache cookie for an inode.
 */
static void afs_get_inode_cache(struct afs_vnode *vnode)
{
#ifdef CONFIG_AFS_FSCACHE
        struct {
                u32 vnode_id;
                u32 unique;
                u32 vnode_id_ext[2];    /* Allow for a 96-bit key */
        } __packed key;
        struct afs_vnode_cache_aux aux;

        if (vnode->status.type == AFS_FTYPE_DIR) {
                vnode->cache = NULL;
                return;
        }

        key.vnode_id            = vnode->fid.vnode;
        key.unique              = vnode->fid.unique;
        key.vnode_id_ext[0]     = vnode->fid.vnode >> 32;
        key.vnode_id_ext[1]     = vnode->fid.vnode_hi;
        aux.data_version        = vnode->status.data_version;

        vnode->cache = fscache_acquire_cookie(vnode->volume->cache,
                                              &afs_vnode_cache_index_def,
                                              &key, sizeof(key),
                                              &aux, sizeof(aux),
                                              vnode, vnode->status.size, true);
#endif
}

/*
 * inode retrieval
 */
struct inode *afs_iget(struct super_block *sb, struct key *key,
                       struct afs_iget_data *iget_data,
                       struct afs_status_cb *scb,
                       struct afs_cb_interest *cbi,
                       struct afs_vnode *parent_vnode)
{
        struct afs_super_info *as;
        struct afs_vnode *vnode;
        struct afs_fid *fid = &iget_data->fid;
        struct inode *inode;
        int ret;

        _enter(",{%llx:%llu.%u},,", fid->vid, fid->vnode, fid->unique);

        as = sb->s_fs_info;
        iget_data->volume = as->volume;

        inode = iget5_locked(sb, fid->vnode, afs_iget5_test, afs_iget5_set,
                             iget_data);
        if (!inode) {
                _leave(" = -ENOMEM");
                return ERR_PTR(-ENOMEM);
        }

        _debug("GOT INODE %p { vl=%llx vn=%llx, 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 (!scb) {
                /* it's a remotely extant inode */
                ret = afs_fetch_status(vnode, key, true, NULL);
                if (ret < 0)
                        goto bad_inode;
        } else {
                ret = afs_inode_init_from_status(vnode, key, cbi, parent_vnode,
                                                 scb);
                if (ret < 0)
                        goto bad_inode;
        }

        afs_get_inode_cache(vnode);

        /* success */
        clear_bit(AFS_VNODE_UNSET, &vnode->flags);
        inode->i_flags |= S_NOATIME;
        unlock_new_inode(inode);
        _leave(" = %p", inode);
        return inode;

        /* failure */
bad_inode:
        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("{%llx:%llu}", vnode->fid.vid, vnode->fid.vnode);

#ifdef CONFIG_AFS_FSCACHE
        fscache_invalidate(vnode->cache);
#endif

        /* 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);
}

/*
 * Check the validity of a vnode/inode.
 */
bool afs_check_validity(struct afs_vnode *vnode)
{
        struct afs_cb_interest *cbi;
        struct afs_server *server;
        struct afs_volume *volume = vnode->volume;
        enum afs_cb_break_reason need_clear = afs_cb_break_no_break;
        time64_t now = ktime_get_real_seconds();
        bool valid;
        unsigned int cb_break, cb_s_break, cb_v_break;
        int seq = 0;

        do {
                read_seqbegin_or_lock(&vnode->cb_lock, &seq);
                cb_v_break = READ_ONCE(volume->cb_v_break);
                cb_break = vnode->cb_break;

                if (test_bit(AFS_VNODE_CB_PROMISED, &vnode->flags)) {
                        cbi = rcu_dereference(vnode->cb_interest);
                        server = rcu_dereference(cbi->server);
                        cb_s_break = READ_ONCE(server->cb_s_break);

                        if (vnode->cb_s_break != cb_s_break ||
                            vnode->cb_v_break != cb_v_break) {
                                vnode->cb_s_break = cb_s_break;
                                vnode->cb_v_break = cb_v_break;
                                need_clear = afs_cb_break_for_vsbreak;
                                valid = false;
                        } else if (test_bit(AFS_VNODE_ZAP_DATA, &vnode->flags)) {
                                need_clear = afs_cb_break_for_zap;
                                valid = false;
                        } else if (vnode->cb_expires_at - 10 <= now) {
                                need_clear = afs_cb_break_for_lapsed;
                                valid = false;
                        } else {
                                valid = true;
                        }
                } else if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) {
                        valid = true;
                } else {
                        vnode->cb_v_break = cb_v_break;
                        valid = false;
                }

        } while (need_seqretry(&vnode->cb_lock, seq));

        done_seqretry(&vnode->cb_lock, seq);

        if (need_clear != afs_cb_break_no_break) {
                write_seqlock(&vnode->cb_lock);
                if (cb_break == vnode->cb_break)
                        __afs_break_callback(vnode, need_clear);
                else
                        trace_afs_cb_miss(&vnode->fid, need_clear);
                write_sequnlock(&vnode->cb_lock);
                valid = false;
        }

        return valid;
}

/*
 * 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)
{
        bool valid;
        int ret;

        _enter("{v={%llx:%llu} fl=%lx},%x",
               vnode->fid.vid, vnode->fid.vnode, vnode->flags,
               key_serial(key));

        rcu_read_lock();
        valid = afs_check_validity(vnode);
        rcu_read_unlock();

        if (test_bit(AFS_VNODE_DELETED, &vnode->flags))
                clear_nlink(&vnode->vfs_inode);

        if (valid)
                goto valid;

        down_write(&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 (!test_bit(AFS_VNODE_CB_PROMISED, &vnode->flags)) {
                _debug("not promised");
                ret = afs_fetch_status(vnode, key, false, NULL);
                if (ret < 0) {
                        if (ret == -ENOENT) {
                                set_bit(AFS_VNODE_DELETED, &vnode->flags);
                                ret = -ESTALE;
                        }
                        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);
        up_write(&vnode->validate_lock);
valid:
        _leave(" = 0");
        return 0;

error_unlock:
        up_write(&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);
        struct afs_vnode *vnode = AFS_FS_I(inode);
        int seq = 0;

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

        do {
                read_seqbegin_or_lock(&vnode->cb_lock, &seq);
                generic_fillattr(inode, stat);
        } while (need_seqretry(&vnode->cb_lock, seq));

        done_seqretry(&vnode->cb_lock, seq);
        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_cb_interest *cbi;
        struct afs_vnode *vnode;

        vnode = AFS_FS_I(inode);

        _enter("{%llx:%llu.%d}",
               vnode->fid.vid,
               vnode->fid.vnode,
               vnode->fid.unique);

        _debug("CLEAR INODE %p", inode);

        ASSERTCMP(inode->i_ino, ==, vnode->fid.vnode);

        truncate_inode_pages_final(&inode->i_data);
        clear_inode(inode);

        write_seqlock(&vnode->cb_lock);
        cbi = rcu_dereference_protected(vnode->cb_interest,
                                        lockdep_is_held(&vnode->cb_lock.lock));
        if (cbi) {
                afs_put_cb_interest(afs_i2net(inode), cbi);
                rcu_assign_pointer(vnode->cb_interest, NULL);
        }
        write_sequnlock(&vnode->cb_lock);

        while (!list_empty(&vnode->wb_keys)) {
                struct afs_wb_key *wbk = list_entry(vnode->wb_keys.next,
                                                    struct afs_wb_key, vnode_link);
                list_del(&wbk->vnode_link);
                afs_put_wb_key(wbk);
        }

#ifdef CONFIG_AFS_FSCACHE
        {
                struct afs_vnode_cache_aux aux;

                aux.data_version = vnode->status.data_version;
                fscache_relinquish_cookie(vnode->cache, &aux,
                                          test_bit(AFS_VNODE_DELETED, &vnode->flags));
                vnode->cache = NULL;
        }
#endif

        afs_prune_wb_keys(vnode);
        afs_put_permits(rcu_access_pointer(vnode->permit_cache));
        key_put(vnode->silly_key);
        vnode->silly_key = NULL;
        key_put(vnode->lock_key);
        vnode->lock_key = NULL;
        _leave("");
}

/*
 * set the attributes of an inode
 */
int afs_setattr(struct dentry *dentry, struct iattr *attr)
{
        struct afs_fs_cursor fc;
        struct afs_status_cb *scb;
        struct afs_vnode *vnode = AFS_FS_I(d_inode(dentry));
        struct key *key;
        int ret = -ENOMEM;

        _enter("{%llx:%llu},{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;
        }

        scb = kzalloc(sizeof(struct afs_status_cb), GFP_KERNEL);
        if (!scb)
                goto error;

        /* 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);

        if (attr->ia_valid & ATTR_FILE) {
                key = afs_file_key(attr->ia_file);
        } else {
                key = afs_request_key(vnode->volume->cell);
                if (IS_ERR(key)) {
                        ret = PTR_ERR(key);
                        goto error_scb;
                }
        }

        ret = -ERESTARTSYS;
        if (afs_begin_vnode_operation(&fc, vnode, key, false)) {
                afs_dataversion_t data_version = vnode->status.data_version;

                if (attr->ia_valid & ATTR_SIZE)
                        data_version++;

                while (afs_select_fileserver(&fc)) {
                        fc.cb_break = afs_calc_vnode_cb_break(vnode);
                        afs_fs_setattr(&fc, attr, scb);
                }

                afs_check_for_remote_deletion(&fc, vnode);
                afs_vnode_commit_status(&fc, vnode, fc.cb_break,
                                        &data_version, scb);
                ret = afs_end_vnode_operation(&fc);
        }

        if (!(attr->ia_valid & ATTR_FILE))
                key_put(key);

error_scb:
        kfree(scb);
error:
        _leave(" = %d", ret);
        return ret;
}