// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2017-2018 HUAWEI, Inc.
 *             https://www.huawei.com/
 * Copyright (C) 2021, Alibaba Cloud
 */
#include "internal.h"
#include <linux/filelock.h>
#include <linux/sched/mm.h>
#include <trace/events/erofs.h>

void erofs_unmap_metabuf(struct erofs_buf *buf)
{
        if (!buf->base)
                return;
        kunmap_local(buf->base);
        buf->base = NULL;
}

void erofs_put_metabuf(struct erofs_buf *buf)
{
        if (!buf->page)
                return;
        erofs_unmap_metabuf(buf);
        folio_put(page_folio(buf->page));
        buf->page = NULL;
}

void *erofs_bread(struct erofs_buf *buf, erofs_off_t offset, bool need_kmap)
{
        pgoff_t index = (buf->off + offset) >> PAGE_SHIFT;
        struct folio *folio = NULL;

        if (buf->page) {
                folio = page_folio(buf->page);
                if (folio_file_page(folio, index) != buf->page)
                        erofs_unmap_metabuf(buf);
        }
        if (!folio || !folio_contains(folio, index)) {
                erofs_put_metabuf(buf);
                folio = read_mapping_folio(buf->mapping, index, buf->file);
                if (IS_ERR(folio))
                        return folio;
        }
        buf->page = folio_file_page(folio, index);
        if (!need_kmap)
                return NULL;
        if (!buf->base)
                buf->base = kmap_local_page(buf->page);
        return buf->base + (offset & ~PAGE_MASK);
}

int erofs_init_metabuf(struct erofs_buf *buf, struct super_block *sb,
                       bool in_metabox)
{
        struct erofs_sb_info *sbi = EROFS_SB(sb);

        buf->file = NULL;
        if (in_metabox) {
                if (unlikely(!sbi->metabox_inode))
                        return -EFSCORRUPTED;
                buf->mapping = sbi->metabox_inode->i_mapping;
                return 0;
        }
        buf->off = sbi->dif0.fsoff;
        if (erofs_is_fileio_mode(sbi)) {
                buf->file = sbi->dif0.file;     /* some fs like FUSE needs it */
                buf->mapping = buf->file->f_mapping;
        } else if (erofs_is_fscache_mode(sb))
                buf->mapping = sbi->dif0.fscache->inode->i_mapping;
        else
                buf->mapping = sb->s_bdev->bd_mapping;
        return 0;
}

void *erofs_read_metabuf(struct erofs_buf *buf, struct super_block *sb,
                         erofs_off_t offset, bool in_metabox)
{
        int err;

        err = erofs_init_metabuf(buf, sb, in_metabox);
        if (err)
                return ERR_PTR(err);
        return erofs_bread(buf, offset, true);
}

int erofs_map_blocks(struct inode *inode, struct erofs_map_blocks *map)
{
        struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
        struct super_block *sb = inode->i_sb;
        unsigned int unit, blksz = sb->s_blocksize;
        struct erofs_inode *vi = EROFS_I(inode);
        struct erofs_inode_chunk_index *idx;
        erofs_blk_t startblk, addrmask;
        bool tailpacking;
        erofs_off_t pos;
        u64 chunknr;
        int err = 0;

        trace_erofs_map_blocks_enter(inode, map, 0);
        map->m_deviceid = 0;
        map->m_flags = 0;
        if (map->m_la >= inode->i_size)
                goto out;

        if (vi->datalayout != EROFS_INODE_CHUNK_BASED) {
                tailpacking = (vi->datalayout == EROFS_INODE_FLAT_INLINE);
                if (!tailpacking && vi->startblk == EROFS_NULL_ADDR)
                        goto out;
                pos = erofs_pos(sb, erofs_iblks(inode) - tailpacking);

                map->m_flags = EROFS_MAP_MAPPED;
                if (map->m_la < pos) {
                        map->m_pa = erofs_pos(sb, vi->startblk) + map->m_la;
                        map->m_llen = pos - map->m_la;
                } else {
                        map->m_pa = erofs_iloc(inode) + vi->inode_isize +
                                vi->xattr_isize + erofs_blkoff(sb, map->m_la);
                        map->m_llen = inode->i_size - map->m_la;
                        map->m_flags |= EROFS_MAP_META;
                }
                goto out;
        }

        if (vi->chunkformat & EROFS_CHUNK_FORMAT_INDEXES)
                unit = sizeof(*idx);                    /* chunk index */
        else
                unit = EROFS_BLOCK_MAP_ENTRY_SIZE;      /* block map */

        chunknr = map->m_la >> vi->chunkbits;
        pos = ALIGN(erofs_iloc(inode) + vi->inode_isize +
                    vi->xattr_isize, unit) + unit * chunknr;

        idx = erofs_read_metabuf(&buf, sb, pos, erofs_inode_in_metabox(inode));
        if (IS_ERR(idx)) {
                err = PTR_ERR(idx);
                goto out;
        }
        map->m_la = chunknr << vi->chunkbits;
        map->m_llen = min_t(erofs_off_t, 1UL << vi->chunkbits,
                            round_up(inode->i_size - map->m_la, blksz));
        if (vi->chunkformat & EROFS_CHUNK_FORMAT_INDEXES) {
                addrmask = (vi->chunkformat & EROFS_CHUNK_FORMAT_48BIT) ?
                        BIT_ULL(48) - 1 : BIT_ULL(32) - 1;
                startblk = (((u64)le16_to_cpu(idx->startblk_hi) << 32) |
                            le32_to_cpu(idx->startblk_lo)) & addrmask;
                if ((startblk ^ EROFS_NULL_ADDR) & addrmask) {
                        map->m_deviceid = le16_to_cpu(idx->device_id) &
                                EROFS_SB(sb)->device_id_mask;
                        map->m_pa = erofs_pos(sb, startblk);
                        map->m_flags = EROFS_MAP_MAPPED;
                }
        } else {
                startblk = le32_to_cpu(*(__le32 *)idx);
                if (startblk != (u32)EROFS_NULL_ADDR) {
                        map->m_pa = erofs_pos(sb, startblk);
                        map->m_flags = EROFS_MAP_MAPPED;
                }
        }
        erofs_put_metabuf(&buf);
out:
        if (!err) {
                map->m_plen = map->m_llen;
                /* inline data should be located in the same meta block */
                if ((map->m_flags & EROFS_MAP_META) &&
                    erofs_blkoff(sb, map->m_pa) + map->m_plen > blksz) {
                        erofs_err(sb, "inline data across blocks @ nid %llu", vi->nid);
                        DBG_BUGON(1);
                        return -EFSCORRUPTED;
                }
        }
        trace_erofs_map_blocks_exit(inode, map, 0, err);
        return err;
}

static void erofs_fill_from_devinfo(struct erofs_map_dev *map,
                struct super_block *sb, struct erofs_device_info *dif)
{
        map->m_sb = sb;
        map->m_dif = dif;
        map->m_bdev = NULL;
        if (dif->file && S_ISBLK(file_inode(dif->file)->i_mode))
                map->m_bdev = file_bdev(dif->file);
}

int erofs_map_dev(struct super_block *sb, struct erofs_map_dev *map)
{
        struct erofs_dev_context *devs = EROFS_SB(sb)->devs;
        struct erofs_device_info *dif;
        erofs_off_t startoff;
        int id;

        erofs_fill_from_devinfo(map, sb, &EROFS_SB(sb)->dif0);
        map->m_bdev = sb->s_bdev;       /* use s_bdev for the primary device */
        if (map->m_deviceid) {
                down_read(&devs->rwsem);
                dif = idr_find(&devs->tree, map->m_deviceid - 1);
                if (!dif) {
                        up_read(&devs->rwsem);
                        return -ENODEV;
                }
                if (devs->flatdev) {
                        map->m_pa += erofs_pos(sb, dif->uniaddr);
                        up_read(&devs->rwsem);
                        return 0;
                }
                erofs_fill_from_devinfo(map, sb, dif);
                up_read(&devs->rwsem);
        } else if (devs->extra_devices && !devs->flatdev) {
                down_read(&devs->rwsem);
                idr_for_each_entry(&devs->tree, dif, id) {
                        if (!dif->uniaddr)
                                continue;

                        startoff = erofs_pos(sb, dif->uniaddr);
                        if (map->m_pa >= startoff &&
                            map->m_pa < startoff + erofs_pos(sb, dif->blocks)) {
                                map->m_pa -= startoff;
                                erofs_fill_from_devinfo(map, sb, dif);
                                break;
                        }
                }
                up_read(&devs->rwsem);
        }
        return 0;
}

/*
 * bit 30: I/O error occurred on this folio
 * bit 29: CPU has dirty data in D-cache (needs aliasing handling);
 * bit 0 - 29: remaining parts to complete this folio
 */
#define EROFS_ONLINEFOLIO_EIO           30
#define EROFS_ONLINEFOLIO_DIRTY         29

void erofs_onlinefolio_init(struct folio *folio)
{
        union {
                atomic_t o;
                void *v;
        } u = { .o = ATOMIC_INIT(1) };

        folio->private = u.v;   /* valid only if file-backed folio is locked */
}

void erofs_onlinefolio_split(struct folio *folio)
{
        atomic_inc((atomic_t *)&folio->private);
}

void erofs_onlinefolio_end(struct folio *folio, int err, bool dirty)
{
        int orig, v;

        do {
                orig = atomic_read((atomic_t *)&folio->private);
                DBG_BUGON(orig <= 0);
                v = dirty << EROFS_ONLINEFOLIO_DIRTY;
                v |= (orig - 1) | (!!err << EROFS_ONLINEFOLIO_EIO);
        } while (atomic_cmpxchg((atomic_t *)&folio->private, orig, v) != orig);

        if (v & (BIT(EROFS_ONLINEFOLIO_DIRTY) - 1))
                return;
        folio->private = 0;
        if (v & BIT(EROFS_ONLINEFOLIO_DIRTY))
                flush_dcache_folio(folio);
        folio_end_read(folio, !(v & BIT(EROFS_ONLINEFOLIO_EIO)));
}

struct erofs_iomap_iter_ctx {
        struct page *page;
        void *base;
        struct inode *realinode;
};

static int erofs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
                unsigned int flags, struct iomap *iomap, struct iomap *srcmap)
{
        struct iomap_iter *iter = container_of(iomap, struct iomap_iter, iomap);
        struct erofs_iomap_iter_ctx *ctx = iter->private;
        struct inode *realinode = ctx ? ctx->realinode : inode;
        struct super_block *sb = realinode->i_sb;
        struct erofs_map_blocks map;
        struct erofs_map_dev mdev;
        int ret;

        map.m_la = offset;
        map.m_llen = length;
        ret = erofs_map_blocks(realinode, &map);
        if (ret < 0)
                return ret;

        iomap->offset = map.m_la;
        iomap->length = map.m_llen;
        iomap->flags = 0;
        iomap->addr = IOMAP_NULL_ADDR;
        if (!(map.m_flags & EROFS_MAP_MAPPED)) {
                iomap->type = IOMAP_HOLE;
                return 0;
        }

        if (!(map.m_flags & EROFS_MAP_META) || !erofs_inode_in_metabox(realinode)) {
                mdev = (struct erofs_map_dev) {
                        .m_deviceid = map.m_deviceid,
                        .m_pa = map.m_pa,
                };
                ret = erofs_map_dev(sb, &mdev);
                if (ret)
                        return ret;

                if (flags & IOMAP_DAX)
                        iomap->dax_dev = mdev.m_dif->dax_dev;
                else
                        iomap->bdev = mdev.m_bdev;
                iomap->addr = mdev.m_dif->fsoff + mdev.m_pa;
                if (flags & IOMAP_DAX)
                        iomap->addr += mdev.m_dif->dax_part_off;
        }

        if (map.m_flags & EROFS_MAP_META) {
                iomap->type = IOMAP_INLINE;
                /* read context should read the inlined data */
                if (ctx) {
                        struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
                        void *ptr;

                        ptr = erofs_read_metabuf(&buf, sb, map.m_pa,
                                                 erofs_inode_in_metabox(realinode));
                        if (IS_ERR(ptr))
                                return PTR_ERR(ptr);
                        iomap->inline_data = ptr;
                        ctx->page = buf.page;
                        ctx->base = buf.base;
                }
        } else {
                iomap->type = IOMAP_MAPPED;
        }
        return 0;
}

static int erofs_iomap_end(struct inode *inode, loff_t pos, loff_t length,
                ssize_t written, unsigned int flags, struct iomap *iomap)
{
        struct iomap_iter *iter = container_of(iomap, struct iomap_iter, iomap);
        struct erofs_iomap_iter_ctx *ctx = iter->private;

        if (ctx && ctx->base) {
                struct erofs_buf buf = {
                        .page = ctx->page,
                        .base = ctx->base,
                };

                DBG_BUGON(iomap->type != IOMAP_INLINE);
                erofs_put_metabuf(&buf);
                ctx->base = NULL;
        }
        return written;
}

static const struct iomap_ops erofs_iomap_ops = {
        .iomap_begin = erofs_iomap_begin,
        .iomap_end = erofs_iomap_end,
};

int erofs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
                 u64 start, u64 len)
{
        if (erofs_inode_is_data_compressed(EROFS_I(inode)->datalayout)) {
                if (!IS_ENABLED(CONFIG_EROFS_FS_ZIP))
                        return -EOPNOTSUPP;
                return iomap_fiemap(inode, fieinfo, start, len,
                                    &z_erofs_iomap_report_ops);
        }
        return iomap_fiemap(inode, fieinfo, start, len, &erofs_iomap_ops);
}

/*
 * since we dont have write or truncate flows, so no inode
 * locking needs to be held at the moment.
 */
static int erofs_read_folio(struct file *file, struct folio *folio)
{
        struct iomap_read_folio_ctx read_ctx = {
                .ops            = &iomap_bio_read_ops,
                .cur_folio      = folio,
        };
        bool need_iput;
        struct erofs_iomap_iter_ctx iter_ctx = {
                .realinode = erofs_real_inode(folio_inode(folio), &need_iput),
        };

        trace_erofs_read_folio(iter_ctx.realinode, folio, true);
        iomap_read_folio(&erofs_iomap_ops, &read_ctx, &iter_ctx);
        if (need_iput)
                iput(iter_ctx.realinode);
        return 0;
}

static void erofs_readahead(struct readahead_control *rac)
{
        struct iomap_read_folio_ctx read_ctx = {
                .ops            = &iomap_bio_read_ops,
                .rac            = rac,
        };
        bool need_iput;
        struct erofs_iomap_iter_ctx iter_ctx = {
                .realinode = erofs_real_inode(rac->mapping->host, &need_iput),
        };

        trace_erofs_readahead(iter_ctx.realinode, readahead_index(rac),
                              readahead_count(rac), true);
        iomap_readahead(&erofs_iomap_ops, &read_ctx, &iter_ctx);
        if (need_iput)
                iput(iter_ctx.realinode);
}

static sector_t erofs_bmap(struct address_space *mapping, sector_t block)
{
        return iomap_bmap(mapping, block, &erofs_iomap_ops);
}

static ssize_t erofs_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
        struct inode *inode = file_inode(iocb->ki_filp);

        /* no need taking (shared) inode lock since it's a ro filesystem */
        if (!iov_iter_count(to))
                return 0;

        if (IS_ENABLED(CONFIG_FS_DAX) && IS_DAX(inode))
                return dax_iomap_rw(iocb, to, &erofs_iomap_ops);

        if ((iocb->ki_flags & IOCB_DIRECT) && inode->i_sb->s_bdev) {
                struct erofs_iomap_iter_ctx iter_ctx = {
                        .realinode = inode,
                };

                return iomap_dio_rw(iocb, to, &erofs_iomap_ops,
                                    NULL, 0, &iter_ctx, 0);
        }
        return filemap_read(iocb, to, 0);
}

/* for uncompressed (aligned) files and raw access for other files */
const struct address_space_operations erofs_aops = {
        .read_folio = erofs_read_folio,
        .readahead = erofs_readahead,
        .bmap = erofs_bmap,
        .direct_IO = noop_direct_IO,
        .release_folio = iomap_release_folio,
        .invalidate_folio = iomap_invalidate_folio,
};

#ifdef CONFIG_FS_DAX
static vm_fault_t erofs_dax_huge_fault(struct vm_fault *vmf,
                unsigned int order)
{
        return dax_iomap_fault(vmf, order, NULL, NULL, &erofs_iomap_ops);
}

static vm_fault_t erofs_dax_fault(struct vm_fault *vmf)
{
        return erofs_dax_huge_fault(vmf, 0);
}

static const struct vm_operations_struct erofs_dax_vm_ops = {
        .fault          = erofs_dax_fault,
        .huge_fault     = erofs_dax_huge_fault,
};

static int erofs_file_mmap_prepare(struct vm_area_desc *desc)
{
        if (!IS_DAX(file_inode(desc->file)))
                return generic_file_readonly_mmap_prepare(desc);

        if (vma_desc_test_flags(desc, VMA_SHARED_BIT) &&
            vma_desc_test_flags(desc, VMA_MAYWRITE_BIT))
                return -EINVAL;

        desc->vm_ops = &erofs_dax_vm_ops;
        vma_desc_set_flags(desc, VMA_HUGEPAGE_BIT);
        return 0;
}
#else
#define erofs_file_mmap_prepare generic_file_readonly_mmap_prepare
#endif

static loff_t erofs_file_llseek(struct file *file, loff_t offset, int whence)
{
        struct inode *inode = file->f_mapping->host;
        const struct iomap_ops *ops = &erofs_iomap_ops;

        if (erofs_inode_is_data_compressed(EROFS_I(inode)->datalayout)) {
                if (!IS_ENABLED(CONFIG_EROFS_FS_ZIP))
                        return generic_file_llseek(file, offset, whence);
                ops = &z_erofs_iomap_report_ops;
        }

        if (whence == SEEK_HOLE)
                offset = iomap_seek_hole(inode, offset, ops);
        else if (whence == SEEK_DATA)
                offset = iomap_seek_data(inode, offset, ops);
        else
                return generic_file_llseek(file, offset, whence);

        if (offset < 0)
                return offset;
        return vfs_setpos(file, offset, inode->i_sb->s_maxbytes);
}

const struct file_operations erofs_file_fops = {
        .llseek         = erofs_file_llseek,
        .read_iter      = erofs_file_read_iter,
        .unlocked_ioctl = erofs_ioctl,
#ifdef CONFIG_COMPAT
        .compat_ioctl   = erofs_compat_ioctl,
#endif
        .mmap_prepare   = erofs_file_mmap_prepare,
        .get_unmapped_area = thp_get_unmapped_area,
        .splice_read    = filemap_splice_read,
        .setlease       = generic_setlease,
};