// SPDX-License-Identifier: GPL-2.0-or-later
/* AFS filesystem file handling
 *
 * Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
 * Written by 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/writeback.h>
#include <linux/gfp.h>
#include <linux/task_io_accounting_ops.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/netfs.h>
#include <trace/events/netfs.h>
#include "internal.h"

static int afs_file_mmap_prepare(struct vm_area_desc *desc);

static ssize_t afs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter);
static ssize_t afs_file_splice_read(struct file *in, loff_t *ppos,
                                    struct pipe_inode_info *pipe,
                                    size_t len, unsigned int flags);
static void afs_vm_open(struct vm_area_struct *area);
static void afs_vm_close(struct vm_area_struct *area);
static vm_fault_t afs_vm_map_pages(struct vm_fault *vmf, pgoff_t start_pgoff, pgoff_t end_pgoff);

const struct file_operations afs_file_operations = {
        .open           = afs_open,
        .release        = afs_release,
        .llseek         = generic_file_llseek,
        .read_iter      = afs_file_read_iter,
        .write_iter     = netfs_file_write_iter,
        .mmap_prepare   = afs_file_mmap_prepare,
        .splice_read    = afs_file_splice_read,
        .splice_write   = iter_file_splice_write,
        .fsync          = afs_fsync,
        .lock           = afs_lock,
        .flock          = afs_flock,
};

const struct inode_operations afs_file_inode_operations = {
        .getattr        = afs_getattr,
        .setattr        = afs_setattr,
        .permission     = afs_permission,
};

const struct address_space_operations afs_file_aops = {
        .direct_IO      = noop_direct_IO,
        .read_folio     = netfs_read_folio,
        .readahead      = netfs_readahead,
        .dirty_folio    = netfs_dirty_folio,
        .release_folio  = netfs_release_folio,
        .invalidate_folio = netfs_invalidate_folio,
        .migrate_folio  = filemap_migrate_folio,
        .writepages     = afs_writepages,
};

static const struct vm_operations_struct afs_vm_ops = {
        .open           = afs_vm_open,
        .close          = afs_vm_close,
        .fault          = filemap_fault,
        .map_pages      = afs_vm_map_pages,
        .page_mkwrite   = afs_page_mkwrite,
};

/*
 * Discard a pin on a writeback key.
 */
void afs_put_wb_key(struct afs_wb_key *wbk)
{
        if (wbk && refcount_dec_and_test(&wbk->usage)) {
                key_put(wbk->key);
                kfree(wbk);
        }
}

/*
 * Cache key for writeback.
 */
int afs_cache_wb_key(struct afs_vnode *vnode, struct afs_file *af)
{
        struct afs_wb_key *wbk, *p;

        wbk = kzalloc_obj(struct afs_wb_key);
        if (!wbk)
                return -ENOMEM;
        refcount_set(&wbk->usage, 2);
        wbk->key = af->key;

        spin_lock(&vnode->wb_lock);
        list_for_each_entry(p, &vnode->wb_keys, vnode_link) {
                if (p->key == wbk->key)
                        goto found;
        }

        key_get(wbk->key);
        list_add_tail(&wbk->vnode_link, &vnode->wb_keys);
        spin_unlock(&vnode->wb_lock);
        af->wb = wbk;
        return 0;

found:
        refcount_inc(&p->usage);
        spin_unlock(&vnode->wb_lock);
        af->wb = p;
        kfree(wbk);
        return 0;
}

/*
 * open an AFS file or directory and attach a key to it
 */
int afs_open(struct inode *inode, struct file *file)
{
        struct afs_vnode *vnode = AFS_FS_I(inode);
        struct afs_file *af;
        struct key *key;
        int ret;

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

        key = afs_request_key(vnode->volume->cell);
        if (IS_ERR(key)) {
                ret = PTR_ERR(key);
                goto error;
        }

        af = kzalloc_obj(*af);
        if (!af) {
                ret = -ENOMEM;
                goto error_key;
        }
        af->key = key;

        ret = afs_validate(vnode, key);
        if (ret < 0)
                goto error_af;

        if (file->f_mode & FMODE_WRITE) {
                ret = afs_cache_wb_key(vnode, af);
                if (ret < 0)
                        goto error_af;
        }

        if (file->f_flags & O_TRUNC)
                set_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);

        fscache_use_cookie(afs_vnode_cache(vnode), file->f_mode & FMODE_WRITE);

        file->private_data = af;
        _leave(" = 0");
        return 0;

error_af:
        kfree(af);
error_key:
        key_put(key);
error:
        _leave(" = %d", ret);
        return ret;
}

/*
 * release an AFS file or directory and discard its key
 */
int afs_release(struct inode *inode, struct file *file)
{
        struct afs_vnode_cache_aux aux;
        struct afs_vnode *vnode = AFS_FS_I(inode);
        struct afs_file *af = file->private_data;
        loff_t i_size;
        int ret = 0;

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

        if ((file->f_mode & FMODE_WRITE))
                ret = vfs_fsync(file, 0);

        file->private_data = NULL;
        if (af->wb)
                afs_put_wb_key(af->wb);

        if ((file->f_mode & FMODE_WRITE)) {
                i_size = i_size_read(&vnode->netfs.inode);
                afs_set_cache_aux(vnode, &aux);
                fscache_unuse_cookie(afs_vnode_cache(vnode), &aux, &i_size);
        } else {
                fscache_unuse_cookie(afs_vnode_cache(vnode), NULL, NULL);
        }

        key_put(af->key);
        kfree(af);
        afs_prune_wb_keys(vnode);
        _leave(" = %d", ret);
        return ret;
}

static void afs_fetch_data_notify(struct afs_operation *op)
{
        struct netfs_io_subrequest *subreq = op->fetch.subreq;

        subreq->error = afs_op_error(op);
        netfs_read_subreq_terminated(subreq);
}

static void afs_fetch_data_success(struct afs_operation *op)
{
        struct afs_vnode *vnode = op->file[0].vnode;

        _enter("op=%08x", op->debug_id);
        afs_vnode_commit_status(op, &op->file[0]);
        afs_stat_v(vnode, n_fetches);
        atomic_long_add(op->fetch.subreq->transferred, &op->net->n_fetch_bytes);
        afs_fetch_data_notify(op);
}

static void afs_fetch_data_aborted(struct afs_operation *op)
{
        afs_check_for_remote_deletion(op);
        afs_fetch_data_notify(op);
}

const struct afs_operation_ops afs_fetch_data_operation = {
        .issue_afs_rpc  = afs_fs_fetch_data,
        .issue_yfs_rpc  = yfs_fs_fetch_data,
        .success        = afs_fetch_data_success,
        .aborted        = afs_fetch_data_aborted,
        .failed         = afs_fetch_data_notify,
};

static void afs_issue_read_call(struct afs_operation *op)
{
        op->call_responded = false;
        op->call_error = 0;
        op->call_abort_code = 0;
        if (test_bit(AFS_SERVER_FL_IS_YFS, &op->server->flags))
                yfs_fs_fetch_data(op);
        else
                afs_fs_fetch_data(op);
}

static void afs_end_read(struct afs_operation *op)
{
        if (op->call_responded && op->server)
                set_bit(AFS_SERVER_FL_RESPONDING, &op->server->flags);

        if (!afs_op_error(op))
                afs_fetch_data_success(op);
        else if (op->cumul_error.aborted)
                afs_fetch_data_aborted(op);
        else
                afs_fetch_data_notify(op);

        afs_end_vnode_operation(op);
        afs_put_operation(op);
}

/*
 * Perform I/O processing on an asynchronous call.  The work item carries a ref
 * to the call struct that we either need to release or to pass on.
 */
static void afs_read_receive(struct afs_call *call)
{
        struct afs_operation *op = call->op;
        enum afs_call_state state;

        _enter("");

        state = READ_ONCE(call->state);
        if (state == AFS_CALL_COMPLETE)
                return;
        trace_afs_read_recv(op, call);

        while (state < AFS_CALL_COMPLETE && READ_ONCE(call->need_attention)) {
                WRITE_ONCE(call->need_attention, false);
                afs_deliver_to_call(call);
                state = READ_ONCE(call->state);
        }

        if (state < AFS_CALL_COMPLETE) {
                netfs_read_subreq_progress(op->fetch.subreq);
                if (rxrpc_kernel_check_life(call->net->socket, call->rxcall))
                        return;
                /* rxrpc terminated the call. */
                afs_set_call_complete(call, call->error, call->abort_code);
        }

        op->call_abort_code     = call->abort_code;
        op->call_error          = call->error;
        op->call_responded      = call->responded;
        op->call                = NULL;
        call->op                = NULL;
        afs_put_call(call);

        /* If the call failed, then we need to crank the server rotation
         * handle and try the next.
         */
        if (afs_select_fileserver(op)) {
                afs_issue_read_call(op);
                return;
        }

        afs_end_read(op);
}

void afs_fetch_data_async_rx(struct work_struct *work)
{
        struct afs_call *call = container_of(work, struct afs_call, async_work);

        afs_read_receive(call);
        afs_put_call(call);
}

void afs_fetch_data_immediate_cancel(struct afs_call *call)
{
        if (call->async) {
                afs_get_call(call, afs_call_trace_wake);
                if (!queue_work(afs_async_calls, &call->async_work))
                        afs_deferred_put_call(call);
                flush_work(&call->async_work);
        }
}

/*
 * Fetch file data from the volume.
 */
static void afs_issue_read(struct netfs_io_subrequest *subreq)
{
        struct afs_operation *op;
        struct afs_vnode *vnode = AFS_FS_I(subreq->rreq->inode);
        struct key *key = subreq->rreq->netfs_priv;

        _enter("%s{%llx:%llu.%u},%x,,,",
               vnode->volume->name,
               vnode->fid.vid,
               vnode->fid.vnode,
               vnode->fid.unique,
               key_serial(key));

        op = afs_alloc_operation(key, vnode->volume);
        if (IS_ERR(op)) {
                subreq->error = PTR_ERR(op);
                netfs_read_subreq_terminated(subreq);
                return;
        }

        afs_op_set_vnode(op, 0, vnode);

        op->fetch.subreq = subreq;
        op->ops         = &afs_fetch_data_operation;

        trace_netfs_sreq(subreq, netfs_sreq_trace_submit);

        if (subreq->rreq->origin == NETFS_READAHEAD ||
            subreq->rreq->iocb) {
                op->flags |= AFS_OPERATION_ASYNC;

                if (!afs_begin_vnode_operation(op)) {
                        subreq->error = afs_put_operation(op);
                        netfs_read_subreq_terminated(subreq);
                        return;
                }

                if (!afs_select_fileserver(op)) {
                        afs_end_read(op);
                        return;
                }

                afs_issue_read_call(op);
        } else {
                afs_do_sync_operation(op);
        }
}

static int afs_init_request(struct netfs_io_request *rreq, struct file *file)
{
        struct afs_vnode *vnode = AFS_FS_I(rreq->inode);

        if (file)
                rreq->netfs_priv = key_get(afs_file_key(file));
        rreq->rsize = 256 * 1024;
        rreq->wsize = 256 * 1024 * 1024;

        switch (rreq->origin) {
        case NETFS_READ_SINGLE:
                if (!file) {
                        struct key *key = afs_request_key(vnode->volume->cell);

                        if (IS_ERR(key))
                                return PTR_ERR(key);
                        rreq->netfs_priv = key;
                }
                break;
        case NETFS_WRITEBACK:
        case NETFS_WRITETHROUGH:
        case NETFS_UNBUFFERED_WRITE:
        case NETFS_DIO_WRITE:
                if (S_ISREG(rreq->inode->i_mode))
                        rreq->io_streams[0].avail = true;
                break;
        case NETFS_WRITEBACK_SINGLE:
        default:
                break;
        }
        return 0;
}

static int afs_check_write_begin(struct file *file, loff_t pos, unsigned len,
                                 struct folio **foliop, void **_fsdata)
{
        struct afs_vnode *vnode = AFS_FS_I(file_inode(file));

        return test_bit(AFS_VNODE_DELETED, &vnode->flags) ? -ESTALE : 0;
}

static void afs_free_request(struct netfs_io_request *rreq)
{
        key_put(rreq->netfs_priv);
        afs_put_wb_key(rreq->netfs_priv2);
}

static void afs_update_i_size(struct inode *inode, loff_t new_i_size)
{
        struct afs_vnode *vnode = AFS_FS_I(inode);
        loff_t i_size;

        write_seqlock(&vnode->cb_lock);
        i_size = i_size_read(&vnode->netfs.inode);
        if (new_i_size > i_size) {
                i_size_write(&vnode->netfs.inode, new_i_size);
                inode_set_bytes(&vnode->netfs.inode, new_i_size);
        }
        write_sequnlock(&vnode->cb_lock);
        fscache_update_cookie(afs_vnode_cache(vnode), NULL, &new_i_size);
}

static void afs_netfs_invalidate_cache(struct netfs_io_request *wreq)
{
        struct afs_vnode *vnode = AFS_FS_I(wreq->inode);

        afs_invalidate_cache(vnode, 0);
}

const struct netfs_request_ops afs_req_ops = {
        .init_request           = afs_init_request,
        .free_request           = afs_free_request,
        .check_write_begin      = afs_check_write_begin,
        .issue_read             = afs_issue_read,
        .update_i_size          = afs_update_i_size,
        .invalidate_cache       = afs_netfs_invalidate_cache,
        .begin_writeback        = afs_begin_writeback,
        .prepare_write          = afs_prepare_write,
        .issue_write            = afs_issue_write,
        .retry_request          = afs_retry_request,
};

static void afs_add_open_mmap(struct afs_vnode *vnode)
{
        if (atomic_inc_return(&vnode->cb_nr_mmap) == 1) {
                down_write(&vnode->volume->open_mmaps_lock);

                if (list_empty(&vnode->cb_mmap_link))
                        list_add_tail(&vnode->cb_mmap_link, &vnode->volume->open_mmaps);

                up_write(&vnode->volume->open_mmaps_lock);
        }
}

static void afs_drop_open_mmap(struct afs_vnode *vnode)
{
        if (atomic_add_unless(&vnode->cb_nr_mmap, -1, 1))
                return;

        down_write(&vnode->volume->open_mmaps_lock);

        read_seqlock_excl(&vnode->cb_lock);
        // the only place where ->cb_nr_mmap may hit 0
        // see __afs_break_callback() for the other side...
        if (atomic_dec_and_test(&vnode->cb_nr_mmap))
                list_del_init(&vnode->cb_mmap_link);
        read_sequnlock_excl(&vnode->cb_lock);

        up_write(&vnode->volume->open_mmaps_lock);
        flush_work(&vnode->cb_work);
}

/*
 * Handle setting up a memory mapping on an AFS file.
 */
static int afs_file_mmap_prepare(struct vm_area_desc *desc)
{
        struct afs_vnode *vnode = AFS_FS_I(file_inode(desc->file));
        int ret;

        afs_add_open_mmap(vnode);

        ret = generic_file_mmap_prepare(desc);
        if (ret == 0)
                desc->vm_ops = &afs_vm_ops;
        else
                afs_drop_open_mmap(vnode);
        return ret;
}

static void afs_vm_open(struct vm_area_struct *vma)
{
        afs_add_open_mmap(AFS_FS_I(file_inode(vma->vm_file)));
}

static void afs_vm_close(struct vm_area_struct *vma)
{
        afs_drop_open_mmap(AFS_FS_I(file_inode(vma->vm_file)));
}

static vm_fault_t afs_vm_map_pages(struct vm_fault *vmf, pgoff_t start_pgoff, pgoff_t end_pgoff)
{
        struct afs_vnode *vnode = AFS_FS_I(file_inode(vmf->vma->vm_file));

        if (afs_check_validity(vnode))
                return filemap_map_pages(vmf, start_pgoff, end_pgoff);
        return 0;
}

static ssize_t afs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
{
        struct inode *inode = file_inode(iocb->ki_filp);
        struct afs_vnode *vnode = AFS_FS_I(inode);
        struct afs_file *af = iocb->ki_filp->private_data;
        ssize_t ret;

        if (iocb->ki_flags & IOCB_DIRECT)
                return netfs_unbuffered_read_iter(iocb, iter);

        ret = netfs_start_io_read(inode);
        if (ret < 0)
                return ret;
        ret = afs_validate(vnode, af->key);
        if (ret == 0)
                ret = filemap_read(iocb, iter, 0);
        netfs_end_io_read(inode);
        return ret;
}

static ssize_t afs_file_splice_read(struct file *in, loff_t *ppos,
                                    struct pipe_inode_info *pipe,
                                    size_t len, unsigned int flags)
{
        struct inode *inode = file_inode(in);
        struct afs_vnode *vnode = AFS_FS_I(inode);
        struct afs_file *af = in->private_data;
        ssize_t ret;

        ret = netfs_start_io_read(inode);
        if (ret < 0)
                return ret;
        ret = afs_validate(vnode, af->key);
        if (ret == 0)
                ret = filemap_splice_read(in, ppos, pipe, len, flags);
        netfs_end_io_read(inode);
        return ret;
}