// SPDX-License-Identifier: GPL-2.0-only
/*
 * truncate.c
 *
 * PURPOSE
 *      Truncate handling routines for the OSTA-UDF(tm) filesystem.
 *
 * COPYRIGHT
 *  (C) 1999-2004 Ben Fennema
 *  (C) 1999 Stelias Computing Inc
 *
 * HISTORY
 *
 *  02/24/99 blf  Created.
 *
 */

#include "udfdecl.h"
#include <linux/fs.h>
#include <linux/mm.h>

#include "udf_i.h"
#include "udf_sb.h"

static void extent_trunc(struct inode *inode, struct extent_position *epos,
                         struct kernel_lb_addr *eloc, int8_t etype, uint32_t elen,
                         uint32_t nelen)
{
        struct kernel_lb_addr neloc = {};
        int last_block = (elen + inode->i_sb->s_blocksize - 1) >>
                inode->i_sb->s_blocksize_bits;
        int first_block = (nelen + inode->i_sb->s_blocksize - 1) >>
                inode->i_sb->s_blocksize_bits;

        if (nelen) {
                if (etype == (EXT_NOT_RECORDED_ALLOCATED >> 30)) {
                        udf_free_blocks(inode->i_sb, inode, eloc, 0,
                                        last_block);
                        etype = (EXT_NOT_RECORDED_NOT_ALLOCATED >> 30);
                } else
                        neloc = *eloc;
                nelen = (etype << 30) | nelen;
        }

        if (elen != nelen) {
                udf_write_aext(inode, epos, &neloc, nelen, 0);
                if (last_block > first_block) {
                        if (etype == (EXT_RECORDED_ALLOCATED >> 30))
                                mark_inode_dirty(inode);

                        if (etype != (EXT_NOT_RECORDED_NOT_ALLOCATED >> 30))
                                udf_free_blocks(inode->i_sb, inode, eloc,
                                                first_block,
                                                last_block - first_block);
                }
        }
}

/*
 * Truncate the last extent to match i_size. This function assumes
 * that preallocation extent is already truncated.
 */
void udf_truncate_tail_extent(struct inode *inode)
{
        struct extent_position epos = {};
        struct kernel_lb_addr eloc;
        uint32_t elen, nelen;
        uint64_t lbcount = 0;
        int8_t etype = -1, netype;
        int adsize;
        struct udf_inode_info *iinfo = UDF_I(inode);
        int ret;

        if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB ||
            inode->i_size == iinfo->i_lenExtents)
                return;
        /* Are we going to delete the file anyway? */
        if (inode->i_nlink == 0)
                return;

        if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_SHORT)
                adsize = sizeof(struct short_ad);
        else if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_LONG)
                adsize = sizeof(struct long_ad);
        else
                BUG();

        /* Find the last extent in the file */
        while (1) {
                ret = udf_next_aext(inode, &epos, &eloc, &elen, &netype, 1);
                if (ret <= 0)
                        break;
                etype = netype;
                lbcount += elen;
                if (lbcount > inode->i_size) {
                        if (lbcount - inode->i_size >= inode->i_sb->s_blocksize)
                                udf_warn(inode->i_sb,
                                         "Too long extent after EOF in inode %u: i_size: %lld lbcount: %lld extent %u+%u\n",
                                         (unsigned)inode->i_ino,
                                         (long long)inode->i_size,
                                         (long long)lbcount,
                                         (unsigned)eloc.logicalBlockNum,
                                         (unsigned)elen);
                        nelen = elen - (lbcount - inode->i_size);
                        epos.offset -= adsize;
                        extent_trunc(inode, &epos, &eloc, etype, elen, nelen);
                        epos.offset += adsize;
                        if (udf_next_aext(inode, &epos, &eloc, &elen,
                                          &netype, 1) > 0)
                                udf_err(inode->i_sb,
                                        "Extent after EOF in inode %u\n",
                                        (unsigned)inode->i_ino);
                        break;
                }
        }
        /* This inode entry is in-memory only and thus we don't have to mark
         * the inode dirty */
        if (ret >= 0)
                iinfo->i_lenExtents = inode->i_size;
        brelse(epos.bh);
}

void udf_discard_prealloc(struct inode *inode)
{
        struct extent_position epos = {};
        struct extent_position prev_epos = {};
        struct kernel_lb_addr eloc;
        uint32_t elen;
        uint64_t lbcount = 0;
        int8_t etype = -1;
        struct udf_inode_info *iinfo = UDF_I(inode);
        int bsize = i_blocksize(inode);
        int8_t tmpetype = -1;
        int ret;

        if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB ||
            ALIGN(inode->i_size, bsize) == ALIGN(iinfo->i_lenExtents, bsize))
                return;

        epos.block = iinfo->i_location;

        /* Find the last extent in the file */
        while (1) {
                ret = udf_next_aext(inode, &epos, &eloc, &elen, &tmpetype, 0);
                if (ret < 0)
                        goto out;
                if (ret == 0)
                        break;
                brelse(prev_epos.bh);
                prev_epos = epos;
                if (prev_epos.bh)
                        get_bh(prev_epos.bh);

                ret = udf_next_aext(inode, &epos, &eloc, &elen, &etype, 1);
                if (ret < 0)
                        goto out;
                lbcount += elen;
        }

        if (etype == (EXT_NOT_RECORDED_ALLOCATED >> 30)) {
                lbcount -= elen;
                udf_delete_aext(inode, prev_epos);
                udf_free_blocks(inode->i_sb, inode, &eloc, 0,
                                DIV_ROUND_UP(elen, bsize));
        }
        /* This inode entry is in-memory only and thus we don't have to mark
         * the inode dirty */
        iinfo->i_lenExtents = lbcount;
out:
        brelse(epos.bh);
        brelse(prev_epos.bh);
}

static void udf_update_alloc_ext_desc(struct inode *inode,
                                      struct extent_position *epos,
                                      u32 lenalloc)
{
        struct super_block *sb = inode->i_sb;
        struct udf_sb_info *sbi = UDF_SB(sb);

        struct allocExtDesc *aed = (struct allocExtDesc *) (epos->bh->b_data);
        int len = sizeof(struct allocExtDesc);

        aed->lengthAllocDescs = cpu_to_le32(lenalloc);
        if (!UDF_QUERY_FLAG(sb, UDF_FLAG_STRICT) || sbi->s_udfrev >= 0x0201)
                len += lenalloc;

        udf_update_tag(epos->bh->b_data, len);
        mark_buffer_dirty_inode(epos->bh, inode);
}

/*
 * Truncate extents of inode to inode->i_size. This function can be used only
 * for making file shorter. For making file longer, udf_extend_file() has to
 * be used.
 */
int udf_truncate_extents(struct inode *inode)
{
        struct extent_position epos;
        struct kernel_lb_addr eloc, neloc = {};
        uint32_t elen, nelen = 0, indirect_ext_len = 0, lenalloc;
        int8_t etype;
        struct super_block *sb = inode->i_sb;
        sector_t first_block = inode->i_size >> sb->s_blocksize_bits, offset;
        loff_t byte_offset;
        int adsize;
        struct udf_inode_info *iinfo = UDF_I(inode);
        int ret = 0;

        if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_SHORT)
                adsize = sizeof(struct short_ad);
        else if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_LONG)
                adsize = sizeof(struct long_ad);
        else
                BUG();

        ret = inode_bmap(inode, first_block, &epos, &eloc, &elen, &offset, &etype);
        if (ret < 0)
                return ret;
        byte_offset = (offset << sb->s_blocksize_bits) +
                (inode->i_size & (sb->s_blocksize - 1));
        if (ret == 0) {
                /* We should extend the file? */
                WARN_ON(byte_offset);
                return 0;
        }
        epos.offset -= adsize;
        extent_trunc(inode, &epos, &eloc, etype, elen, byte_offset);
        epos.offset += adsize;
        if (byte_offset)
                lenalloc = epos.offset;
        else
                lenalloc = epos.offset - adsize;

        if (!epos.bh)
                lenalloc -= udf_file_entry_alloc_offset(inode);
        else
                lenalloc -= sizeof(struct allocExtDesc);

        while ((ret = udf_current_aext(inode, &epos, &eloc,
                                       &elen, &etype, 0)) > 0) {
                if (etype == (EXT_NEXT_EXTENT_ALLOCDESCS >> 30)) {
                        udf_write_aext(inode, &epos, &neloc, nelen, 0);
                        if (indirect_ext_len) {
                                /* We managed to free all extents in the
                                 * indirect extent - free it too */
                                BUG_ON(!epos.bh);
                                udf_free_blocks(sb, NULL, &epos.block,
                                                0, indirect_ext_len);
                        } else if (!epos.bh) {
                                iinfo->i_lenAlloc = lenalloc;
                                mark_inode_dirty(inode);
                        } else
                                udf_update_alloc_ext_desc(inode,
                                                &epos, lenalloc);
                        brelse(epos.bh);
                        epos.offset = sizeof(struct allocExtDesc);
                        epos.block = eloc;
                        epos.bh = sb_bread(sb,
                                        udf_get_lb_pblock(sb, &eloc, 0));
                        /* Error reading indirect block? */
                        if (!epos.bh)
                                return -EIO;
                        if (elen)
                                indirect_ext_len =
                                        (elen + sb->s_blocksize - 1) >>
                                        sb->s_blocksize_bits;
                        else
                                indirect_ext_len = 1;
                } else {
                        extent_trunc(inode, &epos, &eloc, etype, elen, 0);
                        epos.offset += adsize;
                }
        }

        if (ret < 0) {
                brelse(epos.bh);
                return ret;
        }

        if (indirect_ext_len) {
                BUG_ON(!epos.bh);
                udf_free_blocks(sb, NULL, &epos.block, 0, indirect_ext_len);
        } else if (!epos.bh) {
                iinfo->i_lenAlloc = lenalloc;
                mark_inode_dirty(inode);
        } else
                udf_update_alloc_ext_desc(inode, &epos, lenalloc);
        iinfo->i_lenExtents = inode->i_size;

        brelse(epos.bh);
        return 0;
}