/*
 * 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,
};

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_operation *op,
                                      struct afs_vnode_param *vp,
                                      struct afs_vnode *vnode)
{
        struct afs_file_status *status = &vp->scb.status;
        struct inode *inode = AFS_VNODE_TO_I(vnode);
        struct timespec64 t;

        _enter("{%llx:%llu.%u} %s",
               vp->fid.vid, vp->fid.vnode, vp->fid.unique,
               op->type ? op->type->name : "???");

        _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->cb_v_break = op->cb_v_break;
        vnode->cb_s_break = op->cb_s_break;
        vnode->status = *status;

        t = status->mtime_client;
        inode->i_ctime = t;
        inode->i_mtime = t;
        inode->i_atime = t;
        inode->i_flags |= S_NOATIME;
        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 & S_IALLUGO);
                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 & S_IALLUGO);
                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, op->file[0].vnode != vnode ? op->file[0].vnode : NULL);
                write_sequnlock(&vnode->cb_lock);
                return afs_protocol_error(NULL, 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 (!vp->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 = vp->scb.callback.expires_at;
                vnode->cb_server = op->server;
                set_bit(AFS_VNODE_CB_PROMISED, &vnode->flags);
        }

        write_sequnlock(&vnode->cb_lock);
        return 0;
}

/*
 * Update the core inode struct from a returned status record.
 */
static void afs_apply_status(struct afs_operation *op,
                             struct afs_vnode_param *vp)
{
        struct afs_file_status *status = &vp->scb.status;
        struct afs_vnode *vnode = vp->vnode;
        struct inode *inode = &vnode->vfs_inode;
        struct timespec64 t;
        umode_t mode;
        bool data_changed = false;
        bool change_size = vp->set_size;

        _enter("{%llx:%llu.%u} %s",
               vp->fid.vid, vp->fid.vnode, vp->fid.unique,
               op->type ? op->type->name : "???");

        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, afs_eproto_bad_status);
                return;
        }

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

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

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

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

        t = status->mtime_client;
        inode->i_mtime = t;
        if (vp->update_ctime)
                inode->i_ctime = op->ctime;

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

        vnode->status = *status;

        if (vp->dv_before + vp->dv_delta != status->data_version) {
                if (test_bit(AFS_VNODE_CB_PROMISED, &vnode->flags))
                        pr_warn("kAFS: vnode modified {%llx:%llu} %llx->%llx %s (op=%x)\n",
                                vnode->fid.vid, vnode->fid.vnode,
                                (unsigned long long)vp->dv_before + vp->dv_delta,
                                (unsigned long long)status->data_version,
                                op->type ? op->type->name : "???",
                                op->debug_id);

                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);
                }
                change_size = true;
        } 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;
                change_size = true;
        }

        if (data_changed) {
                inode_set_iversion_raw(inode, status->data_version);

                /* Only update the size if the data version jumped.  If the
                 * file is being modified locally, then we might have our own
                 * idea of what the size should be that's not the same as
                 * what's on the server.
                 */
                if (change_size) {
                        afs_set_i_size(vnode, status->size);
                        inode->i_ctime = t;
                        inode->i_atime = t;
                }
        }
}

/*
 * Apply a callback to a vnode.
 */
static void afs_apply_callback(struct afs_operation *op,
                               struct afs_vnode_param *vp)
{
        struct afs_callback *cb = &vp->scb.callback;
        struct afs_vnode *vnode = vp->vnode;

        if (!afs_cb_is_broken(vp->cb_break_before, vnode)) {
                vnode->cb_expires_at    = cb->expires_at;
                vnode->cb_server        = op->server;
                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_operation *op, struct afs_vnode_param *vp)
{
        struct afs_vnode *vnode = vp->vnode;

        _enter("");

        write_seqlock(&vnode->cb_lock);

        if (vp->scb.have_error) {
                /* A YFS server will return this from RemoveFile2 and AFS and
                 * YFS will return this from InlineBulkStatus.
                 */
                if (vp->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);
                        op->flags &= ~AFS_OPERATION_DIR_CONFLICT;
                }
        } else if (vp->scb.have_status) {
                if (vp->speculative &&
                    (test_bit(AFS_VNODE_MODIFYING, &vnode->flags) ||
                     vp->dv_before != vnode->status.data_version))
                        /* Ignore the result of a speculative bulk status fetch
                         * if it splits around a modification op, thereby
                         * appearing to regress the data version.
                         */
                        goto out;
                afs_apply_status(op, vp);
                if (vp->scb.have_cb)
                        afs_apply_callback(op, vp);
        } else if (vp->op_unlinked && !(op->flags & AFS_OPERATION_DIR_CONFLICT)) {
                drop_nlink(&vnode->vfs_inode);
                if (vnode->vfs_inode.i_nlink == 0) {
                        set_bit(AFS_VNODE_DELETED, &vnode->flags);
                        __afs_break_callback(vnode, afs_cb_break_for_deleted);
                }
        }

out:
        write_sequnlock(&vnode->cb_lock);

        if (vp->scb.have_status)
                afs_cache_permit(vnode, op->key, vp->cb_break_before, &vp->scb);
}

static void afs_fetch_status_success(struct afs_operation *op)
{
        struct afs_vnode_param *vp = &op->file[op->fetch_status.which];
        struct afs_vnode *vnode = vp->vnode;
        int ret;

        if (vnode->vfs_inode.i_state & I_NEW) {
                ret = afs_inode_init_from_status(op, vp, vnode);
                op->error = ret;
                if (ret == 0)
                        afs_cache_permit(vnode, op->key, vp->cb_break_before, &vp->scb);
        } else {
                afs_vnode_commit_status(op, vp);
        }
}

const struct afs_operation_ops afs_fetch_status_operation = {
        .issue_afs_rpc  = afs_fs_fetch_status,
        .issue_yfs_rpc  = yfs_fs_fetch_status,
        .success        = afs_fetch_status_success,
        .aborted        = afs_check_for_remote_deletion,
};

/*
 * 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_operation *op;

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

        op = afs_alloc_operation(key, vnode->volume);
        if (IS_ERR(op))
                return PTR_ERR(op);

        afs_op_set_vnode(op, 0, vnode);

        op->nr_files    = 1;
        op->ops         = &afs_fetch_status_operation;
        afs_begin_vnode_operation(op);
        afs_wait_for_operation(op);

        if (_caller_access)
                *_caller_access = op->file[0].scb.status.caller_access;
        return afs_put_operation(op);
}

/*
 * ilookup() comparator
 */
int afs_ilookup5_test_by_fid(struct inode *inode, void *opaque)
{
        struct afs_vnode *vnode = AFS_FS_I(inode);
        struct afs_fid *fid = opaque;

        return (fid->vnode == vnode->fid.vnode &&
                fid->vnode_hi == vnode->fid.vnode_hi &&
                fid->unique == vnode->fid.unique);
}

/*
 * iget5() comparator
 */
static int afs_iget5_test(struct inode *inode, void *opaque)
{
        struct afs_vnode_param *vp = opaque;
        //struct afs_vnode *vnode = AFS_FS_I(inode);

        return afs_ilookup5_test_by_fid(inode, &vp->fid);
}

/*
 * iget5() inode initialiser
 */
static int afs_iget5_set(struct inode *inode, void *opaque)
{
        struct afs_vnode_param *vp = opaque;
        struct afs_super_info *as = AFS_FS_S(inode->i_sb);
        struct afs_vnode *vnode = AFS_FS_I(inode);

        vnode->volume           = as->volume;
        vnode->fid              = vp->fid;

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

/*
 * 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_FILE) {
                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 afs_operation *op, struct afs_vnode_param *vp)
{
        struct afs_vnode_param *dvp = &op->file[0];
        struct super_block *sb = dvp->vnode->vfs_inode.i_sb;
        struct afs_vnode *vnode;
        struct inode *inode;
        int ret;

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

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

        vnode = AFS_FS_I(inode);

        _debug("GOT INODE %p { vl=%llx vn=%llx, u=%x }",
               inode, vnode->fid.vid, vnode->fid.vnode, vnode->fid.unique);

        /* deal with an existing inode */
        if (!(inode->i_state & I_NEW)) {
                _leave(" = %p", inode);
                return inode;
        }

        ret = afs_inode_init_from_status(op, vp, vnode);
        if (ret < 0)
                goto bad_inode;

        afs_get_inode_cache(vnode);

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

        /* failure */
bad_inode:
        iget_failed(inode);
        _leave(" = %d [bad]", ret);
        return ERR_PTR(ret);
}

static int afs_iget5_set_root(struct inode *inode, void *opaque)
{
        struct afs_super_info *as = AFS_FS_S(inode->i_sb);
        struct afs_vnode *vnode = AFS_FS_I(inode);

        vnode->volume           = as->volume;
        vnode->fid.vid          = as->volume->vid,
        vnode->fid.vnode        = 1;
        vnode->fid.unique       = 1;
        inode->i_ino            = 1;
        inode->i_generation     = 1;
        return 0;
}

/*
 * Set up the root inode for a volume.  This is always vnode 1, unique 1 within
 * the volume.
 */
struct inode *afs_root_iget(struct super_block *sb, struct key *key)
{
        struct afs_super_info *as = AFS_FS_S(sb);
        struct afs_operation *op;
        struct afs_vnode *vnode;
        struct inode *inode;
        int ret;

        _enter(",{%llx},,", as->volume->vid);

        inode = iget5_locked(sb, 1, NULL, afs_iget5_set_root, NULL);
        if (!inode) {
                _leave(" = -ENOMEM");
                return ERR_PTR(-ENOMEM);
        }

        _debug("GOT ROOT INODE %p { vl=%llx }", inode, as->volume->vid);

        BUG_ON(!(inode->i_state & I_NEW));

        vnode = AFS_FS_I(inode);
        vnode->cb_v_break = as->volume->cb_v_break,

        op = afs_alloc_operation(key, as->volume);
        if (IS_ERR(op)) {
                ret = PTR_ERR(op);
                goto error;
        }

        afs_op_set_vnode(op, 0, vnode);

        op->nr_files    = 1;
        op->ops         = &afs_fetch_status_operation;
        ret = afs_do_sync_operation(op);
        if (ret < 0)
                goto error;

        afs_get_inode_cache(vnode);

        clear_bit(AFS_VNODE_UNSET, &vnode->flags);
        unlock_new_inode(inode);
        _leave(" = %p", inode);
        return inode;

error:
        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
 */
static 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);
}

/*
 * Get the server reinit counter for a vnode's current server.
 */
static bool afs_get_s_break_rcu(struct afs_vnode *vnode, unsigned int *_s_break)
{
        struct afs_server_list *slist = rcu_dereference(vnode->volume->servers);
        struct afs_server *server;
        int i;

        for (i = 0; i < slist->nr_servers; i++) {
                server = slist->servers[i].server;
                if (server == vnode->cb_server) {
                        *_s_break = READ_ONCE(server->cb_s_break);
                        return true;
                }
        }

        return false;
}

/*
 * Check the validity of a vnode/inode.
 */
bool afs_check_validity(struct afs_vnode *vnode)
{
        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) &&
                    afs_get_s_break_rcu(vnode, &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(struct user_namespace *mnt_userns, 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(&init_user_ns, inode, stat);
                if (test_bit(AFS_VNODE_SILLY_DELETED, &vnode->flags) &&
                    stat->nlink > 0)
                        stat->nlink -= 1;
        } 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_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);

        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("");
}

static void afs_setattr_success(struct afs_operation *op)
{
        struct afs_vnode_param *vp = &op->file[0];
        struct inode *inode = &vp->vnode->vfs_inode;
        loff_t old_i_size = i_size_read(inode);

        op->setattr.old_i_size = old_i_size;
        afs_vnode_commit_status(op, vp);
        /* inode->i_size has now been changed. */

        if (op->setattr.attr->ia_valid & ATTR_SIZE) {
                loff_t size = op->setattr.attr->ia_size;
                if (size > old_i_size)
                        pagecache_isize_extended(inode, old_i_size, size);
        }
}

static void afs_setattr_edit_file(struct afs_operation *op)
{
        struct afs_vnode_param *vp = &op->file[0];
        struct inode *inode = &vp->vnode->vfs_inode;

        if (op->setattr.attr->ia_valid & ATTR_SIZE) {
                loff_t size = op->setattr.attr->ia_size;
                loff_t i_size = op->setattr.old_i_size;

                if (size < i_size)
                        truncate_pagecache(inode, size);
        }
}

static const struct afs_operation_ops afs_setattr_operation = {
        .issue_afs_rpc  = afs_fs_setattr,
        .issue_yfs_rpc  = yfs_fs_setattr,
        .success        = afs_setattr_success,
        .edit_dir       = afs_setattr_edit_file,
};

/*
 * set the attributes of an inode
 */
int afs_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
                struct iattr *attr)
{
        struct afs_operation *op;
        struct afs_vnode *vnode = AFS_FS_I(d_inode(dentry));
        int ret;

        _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 | ATTR_MTIME_SET | ATTR_TIMES_SET |
                                ATTR_TOUCH))) {
                _leave(" = 0 [unsupported]");
                return 0;
        }

        if (attr->ia_valid & ATTR_SIZE) {
                if (!S_ISREG(vnode->vfs_inode.i_mode))
                        return -EISDIR;

                ret = inode_newsize_ok(&vnode->vfs_inode, attr->ia_size);
                if (ret)
                        return ret;

                if (attr->ia_size == i_size_read(&vnode->vfs_inode))
                        attr->ia_valid &= ~ATTR_SIZE;
        }

        /* 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);

        /* Prevent any new writebacks from starting whilst we do this. */
        down_write(&vnode->validate_lock);

        op = afs_alloc_operation(((attr->ia_valid & ATTR_FILE) ?
                                  afs_file_key(attr->ia_file) : NULL),
                                 vnode->volume);
        if (IS_ERR(op)) {
                ret = PTR_ERR(op);
                goto out_unlock;
        }

        afs_op_set_vnode(op, 0, vnode);
        op->setattr.attr = attr;

        if (attr->ia_valid & ATTR_SIZE) {
                op->file[0].dv_delta = 1;
                op->file[0].set_size = true;
        }
        op->ctime = attr->ia_ctime;
        op->file[0].update_ctime = 1;
        op->file[0].modification = true;

        op->ops = &afs_setattr_operation;
        ret = afs_do_sync_operation(op);

out_unlock:
        up_write(&vnode->validate_lock);
        _leave(" = %d", ret);
        return ret;
}