// SPDX-License-Identifier: GPL-2.0-only
/*
 *  linux/fs/affs/inode.c
 *
 *  (c) 1996  Hans-Joachim Widmaier - Rewritten
 *
 *  (C) 1993  Ray Burr - Modified for Amiga FFS filesystem.
 *
 *  (C) 1992  Eric Youngdale Modified for ISO 9660 filesystem.
 *
 *  (C) 1991  Linus Torvalds - minix filesystem
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/statfs.h>
#include <linux/fs_parser.h>
#include <linux/fs_context.h>
#include <linux/magic.h>
#include <linux/sched.h>
#include <linux/cred.h>
#include <linux/slab.h>
#include <linux/writeback.h>
#include <linux/blkdev.h>
#include <linux/seq_file.h>
#include <linux/iversion.h>
#include "affs.h"

static int affs_statfs(struct dentry *dentry, struct kstatfs *buf);
static int affs_show_options(struct seq_file *m, struct dentry *root);

static void
affs_commit_super(struct super_block *sb, int wait)
{
        struct affs_sb_info *sbi = AFFS_SB(sb);
        struct buffer_head *bh = sbi->s_root_bh;
        struct affs_root_tail *tail = AFFS_ROOT_TAIL(sb, bh);

        lock_buffer(bh);
        affs_secs_to_datestamp(ktime_get_real_seconds(), &tail->disk_change);
        affs_fix_checksum(sb, bh);
        unlock_buffer(bh);

        mark_buffer_dirty(bh);
        if (wait)
                sync_dirty_buffer(bh);
}

static void
affs_put_super(struct super_block *sb)
{
        struct affs_sb_info *sbi = AFFS_SB(sb);
        pr_debug("%s()\n", __func__);

        cancel_delayed_work_sync(&sbi->sb_work);
}

static int
affs_sync_fs(struct super_block *sb, int wait)
{
        affs_commit_super(sb, wait);
        return 0;
}

static void flush_superblock(struct work_struct *work)
{
        struct affs_sb_info *sbi;
        struct super_block *sb;

        sbi = container_of(work, struct affs_sb_info, sb_work.work);
        sb = sbi->sb;

        spin_lock(&sbi->work_lock);
        sbi->work_queued = 0;
        spin_unlock(&sbi->work_lock);

        affs_commit_super(sb, 1);
}

void affs_mark_sb_dirty(struct super_block *sb)
{
        struct affs_sb_info *sbi = AFFS_SB(sb);
        unsigned long delay;

        if (sb_rdonly(sb))
               return;

        spin_lock(&sbi->work_lock);
        if (!sbi->work_queued) {
               delay = msecs_to_jiffies(dirty_writeback_interval * 10);
               queue_delayed_work(system_long_wq, &sbi->sb_work, delay);
               sbi->work_queued = 1;
        }
        spin_unlock(&sbi->work_lock);
}

static struct kmem_cache * affs_inode_cachep;

static struct inode *affs_alloc_inode(struct super_block *sb)
{
        struct affs_inode_info *i;

        i = alloc_inode_sb(sb, affs_inode_cachep, GFP_KERNEL);
        if (!i)
                return NULL;

        inode_set_iversion(&i->vfs_inode, 1);
        i->i_lc = NULL;
        i->i_ext_bh = NULL;
        i->i_pa_cnt = 0;

        return &i->vfs_inode;
}

static void affs_free_inode(struct inode *inode)
{
        kmem_cache_free(affs_inode_cachep, AFFS_I(inode));
}

static void init_once(void *foo)
{
        struct affs_inode_info *ei = (struct affs_inode_info *) foo;

        mutex_init(&ei->i_link_lock);
        mutex_init(&ei->i_ext_lock);
        inode_init_once(&ei->vfs_inode);
}

static int __init init_inodecache(void)
{
        affs_inode_cachep = kmem_cache_create("affs_inode_cache",
                                             sizeof(struct affs_inode_info),
                                             0, (SLAB_RECLAIM_ACCOUNT | SLAB_ACCOUNT),
                                             init_once);
        if (affs_inode_cachep == NULL)
                return -ENOMEM;
        return 0;
}

static void destroy_inodecache(void)
{
        /*
         * Make sure all delayed rcu free inodes are flushed before we
         * destroy cache.
         */
        rcu_barrier();
        kmem_cache_destroy(affs_inode_cachep);
}

static const struct super_operations affs_sops = {
        .alloc_inode    = affs_alloc_inode,
        .free_inode     = affs_free_inode,
        .write_inode    = affs_write_inode,
        .evict_inode    = affs_evict_inode,
        .put_super      = affs_put_super,
        .sync_fs        = affs_sync_fs,
        .statfs         = affs_statfs,
        .show_options   = affs_show_options,
};

enum {
        Opt_bs, Opt_mode, Opt_mufs, Opt_notruncate, Opt_prefix, Opt_protect,
        Opt_reserved, Opt_root, Opt_setgid, Opt_setuid,
        Opt_verbose, Opt_volume, Opt_ignore,
};

struct affs_context {
        kuid_t          uid;            /* uid to override */
        kgid_t          gid;            /* gid to override */
        unsigned int    mode;           /* mode to override */
        unsigned int    reserved;       /* Number of reserved blocks */
        int             root_block;     /* FFS root block number */
        int             blocksize;      /* Initial device blksize */
        char            *prefix;        /* Prefix for volumes and assigns */
        char            volume[32];     /* Vol. prefix for absolute symlinks */
        unsigned long   mount_flags;    /* Options */
};

static const struct fs_parameter_spec affs_param_spec[] = {
        fsparam_u32     ("bs",          Opt_bs),
        fsparam_u32oct  ("mode",        Opt_mode),
        fsparam_flag    ("mufs",        Opt_mufs),
        fsparam_flag    ("nofilenametruncate",  Opt_notruncate),
        fsparam_string  ("prefix",      Opt_prefix),
        fsparam_flag    ("protect",     Opt_protect),
        fsparam_u32     ("reserved",    Opt_reserved),
        fsparam_u32     ("root",        Opt_root),
        fsparam_gid     ("setgid",      Opt_setgid),
        fsparam_uid     ("setuid",      Opt_setuid),
        fsparam_flag    ("verbose",     Opt_verbose),
        fsparam_string  ("volume",      Opt_volume),
        fsparam_flag    ("grpquota",    Opt_ignore),
        fsparam_flag    ("noquota",     Opt_ignore),
        fsparam_flag    ("quota",       Opt_ignore),
        fsparam_flag    ("usrquota",    Opt_ignore),
        {},
};

static int affs_parse_param(struct fs_context *fc, struct fs_parameter *param)
{
        struct affs_context *ctx = fc->fs_private;
        struct fs_parse_result result;
        int n;
        int opt;

        opt = fs_parse(fc, affs_param_spec, param, &result);
        if (opt < 0)
                return opt;

        switch (opt) {
        case Opt_bs:
                n = result.uint_32;
                if (n != 512 && n != 1024 && n != 2048
                    && n != 4096) {
                        pr_warn("Invalid blocksize (512, 1024, 2048, 4096 allowed)\n");
                        return -EINVAL;
                }
                ctx->blocksize = n;
                break;
        case Opt_mode:
                ctx->mode = result.uint_32 & 0777;
                affs_set_opt(ctx->mount_flags, SF_SETMODE);
                break;
        case Opt_mufs:
                affs_set_opt(ctx->mount_flags, SF_MUFS);
                break;
        case Opt_notruncate:
                affs_set_opt(ctx->mount_flags, SF_NO_TRUNCATE);
                break;
        case Opt_prefix:
                kfree(ctx->prefix);
                ctx->prefix = param->string;
                param->string = NULL;
                affs_set_opt(ctx->mount_flags, SF_PREFIX);
                break;
        case Opt_protect:
                affs_set_opt(ctx->mount_flags, SF_IMMUTABLE);
                break;
        case Opt_reserved:
                ctx->reserved = result.uint_32;
                break;
        case Opt_root:
                ctx->root_block = result.uint_32;
                break;
        case Opt_setgid:
                ctx->gid = result.gid;
                affs_set_opt(ctx->mount_flags, SF_SETGID);
                break;
        case Opt_setuid:
                ctx->uid = result.uid;
                affs_set_opt(ctx->mount_flags, SF_SETUID);
                break;
        case Opt_verbose:
                affs_set_opt(ctx->mount_flags, SF_VERBOSE);
                break;
        case Opt_volume:
                strscpy(ctx->volume, param->string, 32);
                break;
        case Opt_ignore:
                /* Silently ignore the quota options */
                break;
        default:
                return -EINVAL;
        }
        return 0;
}

static int affs_show_options(struct seq_file *m, struct dentry *root)
{
        struct super_block *sb = root->d_sb;
        struct affs_sb_info *sbi = AFFS_SB(sb);

        if (sb->s_blocksize)
                seq_printf(m, ",bs=%lu", sb->s_blocksize);
        if (affs_test_opt(sbi->s_flags, SF_SETMODE))
                seq_printf(m, ",mode=%o", sbi->s_mode);
        if (affs_test_opt(sbi->s_flags, SF_MUFS))
                seq_puts(m, ",mufs");
        if (affs_test_opt(sbi->s_flags, SF_NO_TRUNCATE))
                seq_puts(m, ",nofilenametruncate");
        if (affs_test_opt(sbi->s_flags, SF_PREFIX))
                seq_printf(m, ",prefix=%s", sbi->s_prefix);
        if (affs_test_opt(sbi->s_flags, SF_IMMUTABLE))
                seq_puts(m, ",protect");
        if (sbi->s_reserved != 2)
                seq_printf(m, ",reserved=%u", sbi->s_reserved);
        if (sbi->s_root_block != (sbi->s_reserved + sbi->s_partition_size - 1) / 2)
                seq_printf(m, ",root=%u", sbi->s_root_block);
        if (affs_test_opt(sbi->s_flags, SF_SETGID))
                seq_printf(m, ",setgid=%u",
                           from_kgid_munged(&init_user_ns, sbi->s_gid));
        if (affs_test_opt(sbi->s_flags, SF_SETUID))
                seq_printf(m, ",setuid=%u",
                           from_kuid_munged(&init_user_ns, sbi->s_uid));
        if (affs_test_opt(sbi->s_flags, SF_VERBOSE))
                seq_puts(m, ",verbose");
        if (sbi->s_volume[0])
                seq_printf(m, ",volume=%s", sbi->s_volume);
        return 0;
}

/* This function definitely needs to be split up. Some fine day I'll
 * hopefully have the guts to do so. Until then: sorry for the mess.
 */

static int affs_fill_super(struct super_block *sb, struct fs_context *fc)
{
        struct affs_sb_info     *sbi;
        struct affs_context     *ctx = fc->fs_private;
        struct buffer_head      *root_bh = NULL;
        struct buffer_head      *boot_bh;
        struct inode            *root_inode = NULL;
        int                      silent = fc->sb_flags & SB_SILENT;
        int                      size, blocksize;
        u32                      chksum;
        int                      num_bm;
        int                      i, j;
        int                      tmp_flags;     /* fix remount prototype... */
        u8                       sig[4];
        int                      ret;

        sb->s_magic             = AFFS_SUPER_MAGIC;
        sb->s_op                = &affs_sops;
        sb->s_flags |= SB_NODIRATIME;

        sb->s_time_gran = NSEC_PER_SEC;
        sb->s_time_min = sys_tz.tz_minuteswest * 60 + AFFS_EPOCH_DELTA;
        sb->s_time_max = 86400LL * U32_MAX + 86400 + sb->s_time_min;

        sbi = kzalloc_obj(struct affs_sb_info);
        if (!sbi)
                return -ENOMEM;

        sb->s_fs_info = sbi;
        sbi->sb = sb;
        mutex_init(&sbi->s_bmlock);
        spin_lock_init(&sbi->symlink_lock);
        spin_lock_init(&sbi->work_lock);
        INIT_DELAYED_WORK(&sbi->sb_work, flush_superblock);

        sbi->s_flags    = ctx->mount_flags;
        sbi->s_mode     = ctx->mode;
        sbi->s_uid      = ctx->uid;
        sbi->s_gid      = ctx->gid;
        sbi->s_reserved = ctx->reserved;
        sbi->s_prefix   = ctx->prefix;
        ctx->prefix     = NULL;
        memcpy(sbi->s_volume, ctx->volume, 32);

        /* N.B. after this point s_prefix must be released */

        /* Get the size of the device in 512-byte blocks.
         * If we later see that the partition uses bigger
         * blocks, we will have to change it.
         */

        size = bdev_nr_sectors(sb->s_bdev);
        pr_debug("initial blocksize=%d, #blocks=%d\n", 512, size);

        affs_set_blocksize(sb, PAGE_SIZE);
        /* Try to find root block. Its location depends on the block size. */

        i = bdev_logical_block_size(sb->s_bdev);
        j = PAGE_SIZE;
        blocksize = ctx->blocksize;
        if (blocksize > 0) {
                i = j = blocksize;
                size = size / (blocksize / 512);
        }

        for (blocksize = i; blocksize <= j; blocksize <<= 1, size >>= 1) {
                sbi->s_root_block = ctx->root_block;
                if (ctx->root_block < 0)
                        sbi->s_root_block = (ctx->reserved + size - 1) / 2;
                pr_debug("setting blocksize to %d\n", blocksize);
                affs_set_blocksize(sb, blocksize);
                sbi->s_partition_size = size;

                /* The root block location that was calculated above is not
                 * correct if the partition size is an odd number of 512-
                 * byte blocks, which will be rounded down to a number of
                 * 1024-byte blocks, and if there were an even number of
                 * reserved blocks. Ideally, all partition checkers should
                 * report the real number of blocks of the real blocksize,
                 * but since this just cannot be done, we have to try to
                 * find the root block anyways. In the above case, it is one
                 * block behind the calculated one. So we check this one, too.
                 */
                for (num_bm = 0; num_bm < 2; num_bm++) {
                        pr_debug("Dev %s, trying root=%u, bs=%d, "
                                "size=%d, reserved=%d\n",
                                sb->s_id,
                                sbi->s_root_block + num_bm,
                                ctx->blocksize, size, ctx->reserved);
                        root_bh = affs_bread(sb, sbi->s_root_block + num_bm);
                        if (!root_bh)
                                continue;
                        if (!affs_checksum_block(sb, root_bh) &&
                            be32_to_cpu(AFFS_ROOT_HEAD(root_bh)->ptype) == T_SHORT &&
                            be32_to_cpu(AFFS_ROOT_TAIL(sb, root_bh)->stype) == ST_ROOT) {
                                sbi->s_hashsize    = blocksize / 4 - 56;
                                sbi->s_root_block += num_bm;
                                goto got_root;
                        }
                        affs_brelse(root_bh);
                        root_bh = NULL;
                }
        }
        if (!silent)
                pr_err("No valid root block on device %s\n", sb->s_id);
        return -EINVAL;

        /* N.B. after this point bh must be released */
got_root:
        /* Keep super block in cache */
        sbi->s_root_bh = root_bh;
        ctx->root_block = sbi->s_root_block;

        /* Find out which kind of FS we have */
        boot_bh = sb_bread(sb, 0);
        if (!boot_bh) {
                pr_err("Cannot read boot block\n");
                return -EINVAL;
        }
        memcpy(sig, boot_bh->b_data, 4);
        brelse(boot_bh);
        chksum = be32_to_cpu(*(__be32 *)sig);

        /* Dircache filesystems are compatible with non-dircache ones
         * when reading. As long as they aren't supported, writing is
         * not recommended.
         */
        if ((chksum == FS_DCFFS || chksum == MUFS_DCFFS || chksum == FS_DCOFS
             || chksum == MUFS_DCOFS) && !sb_rdonly(sb)) {
                pr_notice("Dircache FS - mounting %s read only\n", sb->s_id);
                sb->s_flags |= SB_RDONLY;
        }
        switch (chksum) {
        case MUFS_FS:
        case MUFS_INTLFFS:
        case MUFS_DCFFS:
                affs_set_opt(sbi->s_flags, SF_MUFS);
                fallthrough;
        case FS_INTLFFS:
        case FS_DCFFS:
                affs_set_opt(sbi->s_flags, SF_INTL);
                break;
        case MUFS_FFS:
                affs_set_opt(sbi->s_flags, SF_MUFS);
                break;
        case FS_FFS:
                break;
        case MUFS_OFS:
                affs_set_opt(sbi->s_flags, SF_MUFS);
                fallthrough;
        case FS_OFS:
                affs_set_opt(sbi->s_flags, SF_OFS);
                sb->s_flags |= SB_NOEXEC;
                break;
        case MUFS_DCOFS:
        case MUFS_INTLOFS:
                affs_set_opt(sbi->s_flags, SF_MUFS);
                fallthrough;
        case FS_DCOFS:
        case FS_INTLOFS:
                affs_set_opt(sbi->s_flags, SF_INTL);
                affs_set_opt(sbi->s_flags, SF_OFS);
                sb->s_flags |= SB_NOEXEC;
                break;
        default:
                pr_err("Unknown filesystem on device %s: %08X\n",
                       sb->s_id, chksum);
                return -EINVAL;
        }

        if (affs_test_opt(ctx->mount_flags, SF_VERBOSE)) {
                u8 len = AFFS_ROOT_TAIL(sb, root_bh)->disk_name[0];
                pr_notice("Mounting volume \"%.*s\": Type=%.3s\\%c, Blocksize=%d\n",
                        len > 31 ? 31 : len,
                        AFFS_ROOT_TAIL(sb, root_bh)->disk_name + 1,
                        sig, sig[3] + '0', blocksize);
        }

        sb->s_flags |= SB_NODEV | SB_NOSUID;

        sbi->s_data_blksize = sb->s_blocksize;
        if (affs_test_opt(sbi->s_flags, SF_OFS))
                sbi->s_data_blksize -= 24;

        tmp_flags = sb->s_flags;
        ret = affs_init_bitmap(sb, &tmp_flags);
        if (ret)
                return ret;
        sb->s_flags = tmp_flags;

        /* set up enough so that it can read an inode */

        root_inode = affs_iget(sb, ctx->root_block);
        if (IS_ERR(root_inode))
                return PTR_ERR(root_inode);

        if (affs_test_opt(AFFS_SB(sb)->s_flags, SF_INTL))
                set_default_d_op(sb, &affs_intl_dentry_operations);
        else
                set_default_d_op(sb, &affs_dentry_operations);

        sb->s_root = d_make_root(root_inode);
        if (!sb->s_root) {
                pr_err("AFFS: Get root inode failed\n");
                return -ENOMEM;
        }

        sb->s_export_op = &affs_export_ops;
        pr_debug("s_flags=%lX\n", sb->s_flags);
        return 0;
}

static int affs_reconfigure(struct fs_context *fc)
{
        struct super_block      *sb = fc->root->d_sb;
        struct affs_context     *ctx = fc->fs_private;
        struct affs_sb_info     *sbi = AFFS_SB(sb);
        int                      res = 0;

        sync_filesystem(sb);
        fc->sb_flags |= SB_NODIRATIME;

        flush_delayed_work(&sbi->sb_work);

        /*
         * NB: Historically, only mount_flags, mode, uid, gic, prefix,
         * and volume are accepted during remount.
         */
        sbi->s_flags = ctx->mount_flags;
        sbi->s_mode  = ctx->mode;
        sbi->s_uid   = ctx->uid;
        sbi->s_gid   = ctx->gid;
        /* protect against readers */
        spin_lock(&sbi->symlink_lock);
        if (ctx->prefix) {
                kfree(sbi->s_prefix);
                sbi->s_prefix = ctx->prefix;
                ctx->prefix = NULL;
        }
        memcpy(sbi->s_volume, ctx->volume, 32);
        spin_unlock(&sbi->symlink_lock);

        if ((bool)(fc->sb_flags & SB_RDONLY) == sb_rdonly(sb))
                return 0;

        if (fc->sb_flags & SB_RDONLY)
                affs_free_bitmap(sb);
        else
                res = affs_init_bitmap(sb, &fc->sb_flags);

        return res;
}

static int
affs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
        struct super_block *sb = dentry->d_sb;
        int              free;
        u64              id = huge_encode_dev(sb->s_bdev->bd_dev);

        pr_debug("%s() partsize=%d, reserved=%d\n",
                 __func__, AFFS_SB(sb)->s_partition_size,
                 AFFS_SB(sb)->s_reserved);

        free          = affs_count_free_blocks(sb);
        buf->f_type    = AFFS_SUPER_MAGIC;
        buf->f_bsize   = sb->s_blocksize;
        buf->f_blocks  = AFFS_SB(sb)->s_partition_size - AFFS_SB(sb)->s_reserved;
        buf->f_bfree   = free;
        buf->f_bavail  = free;
        buf->f_fsid    = u64_to_fsid(id);
        buf->f_namelen = AFFSNAMEMAX;
        return 0;
}

static int affs_get_tree(struct fs_context *fc)
{
        return get_tree_bdev(fc, affs_fill_super);
}

static void affs_kill_sb(struct super_block *sb)
{
        struct affs_sb_info *sbi = AFFS_SB(sb);
        kill_block_super(sb);
        if (sbi) {
                affs_free_bitmap(sb);
                affs_brelse(sbi->s_root_bh);
                kfree(sbi->s_prefix);
                mutex_destroy(&sbi->s_bmlock);
                kfree_rcu(sbi, rcu);
        }
}

static void affs_free_fc(struct fs_context *fc)
{
        struct affs_context *ctx = fc->fs_private;

        kfree(ctx->prefix);
        kfree(ctx);
}

static const struct fs_context_operations affs_context_ops = {
        .parse_param    = affs_parse_param,
        .get_tree       = affs_get_tree,
        .reconfigure    = affs_reconfigure,
        .free           = affs_free_fc,
};

static int affs_init_fs_context(struct fs_context *fc)
{
        struct affs_context *ctx;

        ctx = kzalloc_obj(struct affs_context);
        if (!ctx)
                return -ENOMEM;

        if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE) {
                struct super_block *sb = fc->root->d_sb;
                struct affs_sb_info *sbi = AFFS_SB(sb);

                /*
                 * NB: historically, no options other than volume were
                 * preserved across a remount unless they were explicitly
                 * passed in.
                 */
                memcpy(ctx->volume, sbi->s_volume, 32);
        } else {
                ctx->uid        = current_uid();
                ctx->gid        = current_gid();
                ctx->reserved   = 2;
                ctx->root_block = -1;
                ctx->blocksize  = -1;
                ctx->volume[0]  = ':';
        }

        fc->ops = &affs_context_ops;
        fc->fs_private = ctx;

        return 0;
}

static struct file_system_type affs_fs_type = {
        .owner          = THIS_MODULE,
        .name           = "affs",
        .kill_sb        = affs_kill_sb,
        .fs_flags       = FS_REQUIRES_DEV,
        .init_fs_context = affs_init_fs_context,
        .parameters     = affs_param_spec,
};
MODULE_ALIAS_FS("affs");

static int __init init_affs_fs(void)
{
        int err = init_inodecache();
        if (err)
                goto out1;
        err = register_filesystem(&affs_fs_type);
        if (err)
                goto out;
        return 0;
out:
        destroy_inodecache();
out1:
        return err;
}

static void __exit exit_affs_fs(void)
{
        unregister_filesystem(&affs_fs_type);
        destroy_inodecache();
}

MODULE_DESCRIPTION("Amiga filesystem support for Linux");
MODULE_LICENSE("GPL");

module_init(init_affs_fs)
module_exit(exit_affs_fs)