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root/fs/udf/truncate.c

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DEFINITIONS

This source file includes following definitions.
  1. extent_trunc
  2. udf_truncate_tail_extent
  3. udf_discard_prealloc
  4. udf_update_alloc_ext_desc
  5. udf_truncate_extents

/*
 * truncate.c
 *
 * PURPOSE
 *      Truncate handling routines for the OSTA-UDF(tm) filesystem.
 *
 * COPYRIGHT
 *      This file is distributed under the terms of the GNU General Public
 *      License (GPL). Copies of the GPL can be obtained from:
 *              ftp://prep.ai.mit.edu/pub/gnu/GPL
 *      Each contributing author retains all rights to their own work.
 *
 *  (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 <linux/buffer_head.h>

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

static void extent_trunc(struct inode *inode, struct extent_position *epos,
                         kernel_lb_addr eloc, int8_t etype, uint32_t elen,
                         uint32_t nelen)
{
        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 > 0) {
                        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 = {};
        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);

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

        /* Find the last extent in the file */
        while ((netype = udf_next_aext(inode, &epos, &eloc, &elen, 1)) != -1) {
                etype = netype;
                lbcount += elen;
                if (lbcount > inode->i_size) {
                        if (lbcount - inode->i_size >= inode->i_sb->s_blocksize)
                                printk(KERN_WARNING
                                       "udf_truncate_tail_extent(): Too long "
                                       "extent after EOF in inode %u: i_size: "
                                       "%Ld lbcount: %Ld 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, 1) != -1)
                                printk(KERN_ERR "udf_truncate_tail_extent(): "
                                       "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 */
        iinfo->i_lenExtents = inode->i_size;
        brelse(epos.bh);
}

void udf_discard_prealloc(struct inode *inode)
{
        struct extent_position epos = { NULL, 0, {0, 0} };
        kernel_lb_addr eloc;
        uint32_t elen;
        uint64_t lbcount = 0;
        int8_t etype = -1, netype;
        int adsize;
        struct udf_inode_info *iinfo = UDF_I(inode);

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

        if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_SHORT)
                adsize = sizeof(short_ad);
        else if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_LONG)
                adsize = sizeof(long_ad);
        else
                adsize = 0;

        epos.block = iinfo->i_location;

        /* Find the last extent in the file */
        while ((netype = udf_next_aext(inode, &epos, &eloc, &elen, 1)) != -1) {
                etype = netype;
                lbcount += elen;
        }
        if (etype == (EXT_NOT_RECORDED_ALLOCATED >> 30)) {
                epos.offset -= adsize;
                lbcount -= elen;
                extent_trunc(inode, &epos, eloc, etype, elen, 0);
                if (!epos.bh) {
                        iinfo->i_lenAlloc =
                                epos.offset -
                                udf_file_entry_alloc_offset(inode);
                        mark_inode_dirty(inode);
                } else {
                        struct allocExtDesc *aed =
                                (struct allocExtDesc *)(epos.bh->b_data);
                        aed->lengthAllocDescs =
                                cpu_to_le32(epos.offset -
                                            sizeof(struct allocExtDesc));
                        if (!UDF_QUERY_FLAG(inode->i_sb, UDF_FLAG_STRICT) ||
                            UDF_SB(inode->i_sb)->s_udfrev >= 0x0201)
                                udf_update_tag(epos.bh->b_data, epos.offset);
                        else
                                udf_update_tag(epos.bh->b_data,
                                               sizeof(struct allocExtDesc));
                        mark_buffer_dirty_inode(epos.bh, inode);
                }
        }
        /* This inode entry is in-memory only and thus we don't have to mark
         * the inode dirty */
        iinfo->i_lenExtents = lbcount;
        brelse(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);
}

void udf_truncate_extents(struct inode *inode)
{
        struct extent_position epos;
        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);

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

        etype = inode_bmap(inode, first_block, &epos, &eloc, &elen, &offset);
        byte_offset = (offset << sb->s_blocksize_bits) +
                (inode->i_size & (sb->s_blocksize - 1));
        if (etype != -1) {
                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 ((etype = udf_current_aext(inode, &epos, &eloc,
                                                 &elen, 0)) != -1) {
                        if (etype == (EXT_NEXT_EXTENT_ALLOCDECS >> 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, inode, 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 = udf_tread(sb,
                                                udf_get_lb_pblock(sb, eloc, 0));
                                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 (indirect_ext_len) {
                        BUG_ON(!epos.bh);
                        udf_free_blocks(sb, inode, 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);
        } else if (inode->i_size) {
                if (byte_offset) {
                        kernel_long_ad extent;

                        /*
                         *  OK, there is not extent covering inode->i_size and
                         *  no extent above inode->i_size => truncate is
                         *  extending the file by 'offset' blocks.
                         */
                        if ((!epos.bh &&
                             epos.offset ==
                                        udf_file_entry_alloc_offset(inode)) ||
                            (epos.bh && epos.offset ==
                                                sizeof(struct allocExtDesc))) {
                                /* File has no extents at all or has empty last
                                 * indirect extent! Create a fake extent... */
                                extent.extLocation.logicalBlockNum = 0;
                                extent.extLocation.partitionReferenceNum = 0;
                                extent.extLength =
                                        EXT_NOT_RECORDED_NOT_ALLOCATED;
                        } else {
                                epos.offset -= adsize;
                                etype = udf_next_aext(inode, &epos,
                                                      &extent.extLocation,
                                                      &extent.extLength, 0);
                                extent.extLength |= etype << 30;
                        }
                        udf_extend_file(inode, &epos, &extent,
                                        offset +
                                        ((inode->i_size &
                                                (sb->s_blocksize - 1)) != 0));
                }
        }
        iinfo->i_lenExtents = inode->i_size;

        brelse(epos.bh);
}

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