// 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/filelock.h>
#include <linux/quotaops.h>
#include <linux/iomap.h>
#include <linux/uio.h>
#include <linux/buffer_head.h>
#include "ext2.h"
#include "xattr.h"
#include "acl.h"
#include "trace.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)
 *     address_space->invalidate_lock
 *       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);
        vm_fault_t ret;
        bool write = (vmf->flags & FAULT_FLAG_WRITE) &&
                (vmf->vma->vm_flags & VM_SHARED);

        if (write) {
                sb_start_pagefault(inode->i_sb);
                file_update_time(vmf->vma->vm_file);
        }
        filemap_invalidate_lock_shared(inode->i_mapping);

        ret = dax_iomap_fault(vmf, 0, NULL, NULL, &ext2_iomap_ops);

        filemap_invalidate_unlock_shared(inode->i_mapping);
        if (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_prepare(struct vm_area_desc *desc)
{
        struct file *file = desc->file;

        if (!IS_DAX(file_inode(file)))
                return generic_file_mmap_prepare(desc);

        file_accessed(file);
        desc->vm_ops = &ext2_dax_vm_ops;
        return 0;
}
#else
#define ext2_file_mmap_prepare  generic_file_mmap_prepare
#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_buffers_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_dio_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
        struct file *file = iocb->ki_filp;
        struct inode *inode = file->f_mapping->host;
        ssize_t ret;

        trace_ext2_dio_read_begin(iocb, to, 0);
        inode_lock_shared(inode);
        ret = iomap_dio_rw(iocb, to, &ext2_iomap_ops, NULL, 0, NULL, 0);
        inode_unlock_shared(inode);
        trace_ext2_dio_read_end(iocb, to, ret);

        return ret;
}

static int ext2_dio_write_end_io(struct kiocb *iocb, ssize_t size,
                                 int error, unsigned int flags)
{
        loff_t pos = iocb->ki_pos;
        struct inode *inode = file_inode(iocb->ki_filp);

        if (error)
                goto out;

        /*
         * If we are extending the file, we have to update i_size here before
         * page cache gets invalidated in iomap_dio_rw(). This prevents racing
         * buffered reads from zeroing out too much from page cache pages.
         * Note that all extending writes always happens synchronously with
         * inode lock held by ext2_dio_write_iter(). So it is safe to update
         * inode size here for extending file writes.
         */
        pos += size;
        if (pos > i_size_read(inode)) {
                i_size_write(inode, pos);
                mark_inode_dirty(inode);
        }
out:
        trace_ext2_dio_write_endio(iocb, size, error);
        return error;
}

static const struct iomap_dio_ops ext2_dio_write_ops = {
        .end_io = ext2_dio_write_end_io,
};

static ssize_t ext2_dio_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;
        unsigned int flags = 0;
        unsigned long blocksize = inode->i_sb->s_blocksize;
        loff_t offset = iocb->ki_pos;
        loff_t count = iov_iter_count(from);
        ssize_t status = 0;

        trace_ext2_dio_write_begin(iocb, from, 0);
        inode_lock(inode);
        ret = generic_write_checks(iocb, from);
        if (ret <= 0)
                goto out_unlock;

        ret = kiocb_modified(iocb);
        if (ret)
                goto out_unlock;

        /* use IOMAP_DIO_FORCE_WAIT for unaligned or extending writes */
        if (iocb->ki_pos + iov_iter_count(from) > i_size_read(inode) ||
           (!IS_ALIGNED(iocb->ki_pos | iov_iter_alignment(from), blocksize)))
                flags |= IOMAP_DIO_FORCE_WAIT;

        ret = iomap_dio_rw(iocb, from, &ext2_iomap_ops, &ext2_dio_write_ops,
                           flags, NULL, 0);

        /* ENOTBLK is magic return value for fallback to buffered-io */
        if (ret == -ENOTBLK)
                ret = 0;

        if (ret < 0 && ret != -EIOCBQUEUED)
                ext2_write_failed(inode->i_mapping, offset + count);

        /* handle case for partial write and for fallback to buffered write */
        if (ret >= 0 && iov_iter_count(from)) {
                loff_t pos, endbyte;
                int ret2;

                iocb->ki_flags &= ~IOCB_DIRECT;
                pos = iocb->ki_pos;
                status = generic_perform_write(iocb, from);
                if (unlikely(status < 0)) {
                        ret = status;
                        goto out_unlock;
                }

                ret += status;
                endbyte = pos + status - 1;
                ret2 = filemap_write_and_wait_range(inode->i_mapping, pos,
                                                    endbyte);
                if (!ret2)
                        invalidate_mapping_pages(inode->i_mapping,
                                                 pos >> PAGE_SHIFT,
                                                 endbyte >> PAGE_SHIFT);
                if (ret > 0)
                        generic_write_sync(iocb, ret);
        }

out_unlock:
        inode_unlock(inode);
        if (status)
                trace_ext2_dio_write_buff_end(iocb, from, status);
        trace_ext2_dio_write_end(iocb, from, ret);
        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
        if (iocb->ki_flags & IOCB_DIRECT)
                return ext2_dio_read_iter(iocb, to);

        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
        if (iocb->ki_flags & IOCB_DIRECT)
                return ext2_dio_write_iter(iocb, from);

        return generic_file_write_iter(iocb, from);
}

static int ext2_file_open(struct inode *inode, struct file *filp)
{
        filp->f_mode |= FMODE_CAN_ODIRECT;
        return dquot_file_open(inode, filp);
}

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_prepare   = ext2_file_mmap_prepare,
        .open           = ext2_file_open,
        .release        = ext2_release_file,
        .fsync          = ext2_fsync,
        .get_unmapped_area = thp_get_unmapped_area,
        .splice_read    = filemap_splice_read,
        .splice_write   = iter_file_splice_write,
        .setlease       = generic_setlease,
};

const struct inode_operations ext2_file_inode_operations = {
        .listxattr      = ext2_listxattr,
        .getattr        = ext2_getattr,
        .setattr        = ext2_setattr,
        .get_inode_acl  = ext2_get_acl,
        .set_acl        = ext2_set_acl,
        .fiemap         = ext2_fiemap,
        .fileattr_get   = ext2_fileattr_get,
        .fileattr_set   = ext2_fileattr_set,
};