// SPDX-License-Identifier: GPL-2.0
/*
 *  linux/fs/ext2/file.c
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card (card@masi.ibp.fr)
 * Laboratoire MASI - Institut Blaise Pascal
 * Universite Pierre et Marie Curie (Paris VI)
 *
 *  from
 *
 *  linux/fs/minix/file.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  ext2 fs regular file handling primitives
 *
 *  64-bit file support on 64-bit platforms by Jakub Jelinek
 *      (jj@sunsite.ms.mff.cuni.cz)
 */

#include <linux/time.h>
#include <linux/pagemap.h>
#include <linux/dax.h>
#include <linux/quotaops.h>
#include <linux/iomap.h>
#include <linux/uio.h>
#include "ext2.h"
#include "xattr.h"
#include "acl.h"

#ifdef CONFIG_FS_DAX
static ssize_t ext2_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
        struct inode *inode = iocb->ki_filp->f_mapping->host;
        ssize_t ret;

        if (!iov_iter_count(to))
                return 0; /* skip atime */

        inode_lock_shared(inode);
        ret = dax_iomap_rw(iocb, to, &ext2_iomap_ops);
        inode_unlock_shared(inode);

        file_accessed(iocb->ki_filp);
        return ret;
}

static ssize_t ext2_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
        struct file *file = iocb->ki_filp;
        struct inode *inode = file->f_mapping->host;
        ssize_t ret;

        inode_lock(inode);
        ret = generic_write_checks(iocb, from);
        if (ret <= 0)
                goto out_unlock;
        ret = file_remove_privs(file);
        if (ret)
                goto out_unlock;
        ret = file_update_time(file);
        if (ret)
                goto out_unlock;

        ret = dax_iomap_rw(iocb, from, &ext2_iomap_ops);
        if (ret > 0 && iocb->ki_pos > i_size_read(inode)) {
                i_size_write(inode, iocb->ki_pos);
                mark_inode_dirty(inode);
        }

out_unlock:
        inode_unlock(inode);
        if (ret > 0)
                ret = generic_write_sync(iocb, ret);
        return ret;
}

/*
 * The lock ordering for ext2 DAX fault paths is:
 *
 * mmap_lock (MM)
 *   sb_start_pagefault (vfs, freeze)
 *     ext2_inode_info->dax_sem
 *       address_space->i_mmap_rwsem or page_lock (mutually exclusive in DAX)
 *         ext2_inode_info->truncate_mutex
 *
 * The default page_lock and i_size verification done by non-DAX fault paths
 * is sufficient because ext2 doesn't support hole punching.
 */
static vm_fault_t ext2_dax_fault(struct vm_fault *vmf)
{
        struct inode *inode = file_inode(vmf->vma->vm_file);
        struct ext2_inode_info *ei = EXT2_I(inode);
        vm_fault_t ret;

        if (vmf->flags & FAULT_FLAG_WRITE) {
                sb_start_pagefault(inode->i_sb);
                file_update_time(vmf->vma->vm_file);
        }
        down_read(&ei->dax_sem);

        ret = dax_iomap_fault(vmf, PE_SIZE_PTE, NULL, NULL, &ext2_iomap_ops);

        up_read(&ei->dax_sem);
        if (vmf->flags & FAULT_FLAG_WRITE)
                sb_end_pagefault(inode->i_sb);
        return ret;
}

static const struct vm_operations_struct ext2_dax_vm_ops = {
        .fault          = ext2_dax_fault,
        /*
         * .huge_fault is not supported for DAX because allocation in ext2
         * cannot be reliably aligned to huge page sizes and so pmd faults
         * will always fail and fail back to regular faults.
         */
        .page_mkwrite   = ext2_dax_fault,
        .pfn_mkwrite    = ext2_dax_fault,
};

static int ext2_file_mmap(struct file *file, struct vm_area_struct *vma)
{
        if (!IS_DAX(file_inode(file)))
                return generic_file_mmap(file, vma);

        file_accessed(file);
        vma->vm_ops = &ext2_dax_vm_ops;
        return 0;
}
#else
#define ext2_file_mmap  generic_file_mmap
#endif

/*
 * Called when filp is released. This happens when all file descriptors
 * for a single struct file are closed. Note that different open() calls
 * for the same file yield different struct file structures.
 */
static int ext2_release_file (struct inode * inode, struct file * filp)
{
        if (filp->f_mode & FMODE_WRITE) {
                mutex_lock(&EXT2_I(inode)->truncate_mutex);
                ext2_discard_reservation(inode);
                mutex_unlock(&EXT2_I(inode)->truncate_mutex);
        }
        return 0;
}

int ext2_fsync(struct file *file, loff_t start, loff_t end, int datasync)
{
        int ret;
        struct super_block *sb = file->f_mapping->host->i_sb;

        ret = generic_file_fsync(file, start, end, datasync);
        if (ret == -EIO)
                /* We don't really know where the IO error happened... */
                ext2_error(sb, __func__,
                           "detected IO error when writing metadata buffers");
        return ret;
}

static ssize_t ext2_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
#ifdef CONFIG_FS_DAX
        if (IS_DAX(iocb->ki_filp->f_mapping->host))
                return ext2_dax_read_iter(iocb, to);
#endif
        return generic_file_read_iter(iocb, to);
}

static ssize_t ext2_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
#ifdef CONFIG_FS_DAX
        if (IS_DAX(iocb->ki_filp->f_mapping->host))
                return ext2_dax_write_iter(iocb, from);
#endif
        return generic_file_write_iter(iocb, from);
}

const struct file_operations ext2_file_operations = {
        .llseek         = generic_file_llseek,
        .read_iter      = ext2_file_read_iter,
        .write_iter     = ext2_file_write_iter,
        .unlocked_ioctl = ext2_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl   = ext2_compat_ioctl,
#endif
        .mmap           = ext2_file_mmap,
        .open           = dquot_file_open,
        .release        = ext2_release_file,
        .fsync          = ext2_fsync,
        .get_unmapped_area = thp_get_unmapped_area,
        .splice_read    = generic_file_splice_read,
        .splice_write   = iter_file_splice_write,
};

const struct inode_operations ext2_file_inode_operations = {
        .listxattr      = ext2_listxattr,
        .getattr        = ext2_getattr,
        .setattr        = ext2_setattr,
        .get_acl        = ext2_get_acl,
        .set_acl        = ext2_set_acl,
        .fiemap         = ext2_fiemap,
};