lcnalloc.c

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/*
 * lcnalloc.c - Cluster (de)allocation code.  Part of the Linux-NTFS project.
 *
 * Copyright (c) 2004-2005 Anton Altaparmakov
 *
 * This program/include file is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program/include file is distributed in the hope that it will be
 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program (in the main directory of the Linux-NTFS
 * distribution in the file COPYING); if not, write to the Free Software
 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#ifdef NTFS_RW

#include <linux/pagemap.h>

#include "lcnalloc.h"
#include "debug.h"
#include "bitmap.h"
#include "inode.h"
#include "volume.h"
#include "attrib.h"
#include "malloc.h"
#include "aops.h"
#include "ntfs.h"

int ntfs_cluster_free_from_rl_nolock(ntfs_volume *vol,
        const runlist_element *rl)
{
    struct inode *lcnbmp_vi = vol->lcnbmp_ino;
    int ret = 0;

    ntfs_debug("Entering.");
    if (!rl)
        return 0;
    for (; rl->length; rl++) {
        int err;

        if (rl->lcn < 0)
            continue;
        err = ntfs_bitmap_clear_run(lcnbmp_vi, rl->lcn, rl->length);
        if (unlikely(err && (!ret || ret == -ENOMEM) && ret != err))
            ret = err;
    }
    ntfs_debug("Done.");
    return ret;
}

runlist_element *ntfs_cluster_alloc(ntfs_volume *vol, const VCN start_vcn,
        const s64 count, const LCN start_lcn,
        const NTFS_CLUSTER_ALLOCATION_ZONES zone,
        const bool is_extension)
{
    LCN zone_start, zone_end, bmp_pos, bmp_initial_pos, last_read_pos, lcn;
    LCN prev_lcn = 0, prev_run_len = 0, mft_zone_size;
    s64 clusters;
    loff_t i_size;
    struct inode *lcnbmp_vi;
    runlist_element *rl = NULL;
    struct address_space *mapping;
    struct page *page = NULL;
    u8 *buf, *byte;
    int err = 0, rlpos, rlsize, buf_size;
    u8 pass, done_zones, search_zone, need_writeback = 0, bit;

    ntfs_debug("Entering for start_vcn 0x%llx, count 0x%llx, start_lcn "
            "0x%llx, zone %s_ZONE.", (unsigned long long)start_vcn,
            (unsigned long long)count,
            (unsigned long long)start_lcn,
            zone == MFT_ZONE ? "MFT" : "DATA");
    BUG_ON(!vol);
    lcnbmp_vi = vol->lcnbmp_ino;
    BUG_ON(!lcnbmp_vi);
    BUG_ON(start_vcn < 0);
    BUG_ON(count < 0);
    BUG_ON(start_lcn < -1);
    BUG_ON(zone < FIRST_ZONE);
    BUG_ON(zone > LAST_ZONE);

    /* Return NULL if @count is zero. */
    if (!count)
        return NULL;
    /* Take the lcnbmp lock for writing. */
    down_write(&vol->lcnbmp_lock);
    /*
     * If no specific @start_lcn was requested, use the current data zone
     * position, otherwise use the requested @start_lcn but make sure it
     * lies outside the mft zone.  Also set done_zones to 0 (no zones done)
     * and pass depending on whether we are starting inside a zone (1) or
     * at the beginning of a zone (2).  If requesting from the MFT_ZONE,
     * we either start at the current position within the mft zone or at
     * the specified position.  If the latter is out of bounds then we start
     * at the beginning of the MFT_ZONE.
     */
    done_zones = 0;
    pass = 1;
    /*
     * zone_start and zone_end are the current search range.  search_zone
     * is 1 for mft zone, 2 for data zone 1 (end of mft zone till end of
     * volume) and 4 for data zone 2 (start of volume till start of mft
     * zone).
     */
    zone_start = start_lcn;
    if (zone_start < 0) {
        if (zone == DATA_ZONE)
            zone_start = vol->data1_zone_pos;
        else
            zone_start = vol->mft_zone_pos;
        if (!zone_start) {
            /*
             * Zone starts at beginning of volume which means a
             * single pass is sufficient.
             */
            pass = 2;
        }
    } else if (zone == DATA_ZONE && zone_start >= vol->mft_zone_start &&
            zone_start < vol->mft_zone_end) {
        zone_start = vol->mft_zone_end;
        /*
         * Starting at beginning of data1_zone which means a single
         * pass in this zone is sufficient.
         */
        pass = 2;
    } else if (zone == MFT_ZONE && (zone_start < vol->mft_zone_start ||
            zone_start >= vol->mft_zone_end)) {
        zone_start = vol->mft_lcn;
        if (!vol->mft_zone_end)
            zone_start = 0;
        /*
         * Starting at beginning of volume which means a single pass
         * is sufficient.
         */
        pass = 2;
    }
    if (zone == MFT_ZONE) {
        zone_end = vol->mft_zone_end;
        search_zone = 1;
    } else /* if (zone == DATA_ZONE) */ {
        /* Skip searching the mft zone. */
        done_zones |= 1;
        if (zone_start >= vol->mft_zone_end) {
            zone_end = vol->nr_clusters;
            search_zone = 2;
        } else {
            zone_end = vol->mft_zone_start;
            search_zone = 4;
        }
    }
    /*
     * bmp_pos is the current bit position inside the bitmap.  We use
     * bmp_initial_pos to determine whether or not to do a zone switch.
     */
    bmp_pos = bmp_initial_pos = zone_start;

    /* Loop until all clusters are allocated, i.e. clusters == 0. */
    clusters = count;
    rlpos = rlsize = 0;
    mapping = lcnbmp_vi->i_mapping;
    i_size = i_size_read(lcnbmp_vi);
    while (1) {
        ntfs_debug("Start of outer while loop: done_zones 0x%x, "
                "search_zone %i, pass %i, zone_start 0x%llx, "
                "zone_end 0x%llx, bmp_initial_pos 0x%llx, "
                "bmp_pos 0x%llx, rlpos %i, rlsize %i.",
                done_zones, search_zone, pass,
                (unsigned long long)zone_start,
                (unsigned long long)zone_end,
                (unsigned long long)bmp_initial_pos,
                (unsigned long long)bmp_pos, rlpos, rlsize);
        /* Loop until we run out of free clusters. */
        last_read_pos = bmp_pos >> 3;
        ntfs_debug("last_read_pos 0x%llx.",
                (unsigned long long)last_read_pos);
        if (last_read_pos > i_size) {
            ntfs_debug("End of attribute reached.  "
                    "Skipping to zone_pass_done.");
            goto zone_pass_done;
        }
        if (likely(page)) {
            if (need_writeback) {
                ntfs_debug("Marking page dirty.");
                flush_dcache_page(page);
                set_page_dirty(page);
                need_writeback = 0;
            }
            ntfs_unmap_page(page);
        }
        page = ntfs_map_page(mapping, last_read_pos >>
                PAGE_CACHE_SHIFT);
        if (IS_ERR(page)) {
            err = PTR_ERR(page);
            ntfs_error(vol->sb, "Failed to map page.");
            goto out;
        }
        buf_size = last_read_pos & ~PAGE_CACHE_MASK;
        buf = page_address(page) + buf_size;
        buf_size = PAGE_CACHE_SIZE - buf_size;
        if (unlikely(last_read_pos + buf_size > i_size))
            buf_size = i_size - last_read_pos;
        buf_size <<= 3;
        lcn = bmp_pos & 7;
        bmp_pos &= ~(LCN)7;
        ntfs_debug("Before inner while loop: buf_size %i, lcn 0x%llx, "
                "bmp_pos 0x%llx, need_writeback %i.", buf_size,
                (unsigned long long)lcn,
                (unsigned long long)bmp_pos, need_writeback);
        while (lcn < buf_size && lcn + bmp_pos < zone_end) {
            byte = buf + (lcn >> 3);
            ntfs_debug("In inner while loop: buf_size %i, "
                    "lcn 0x%llx, bmp_pos 0x%llx, "
                    "need_writeback %i, byte ofs 0x%x, "
                    "*byte 0x%x.", buf_size,
                    (unsigned long long)lcn,
                    (unsigned long long)bmp_pos,
                    need_writeback,
                    (unsigned int)(lcn >> 3),
                    (unsigned int)*byte);
            /* Skip full bytes. */
            if (*byte == 0xff) {
                lcn = (lcn + 8) & ~(LCN)7;
                ntfs_debug("Continuing while loop 1.");
                continue;
            }
            bit = 1 << (lcn & 7);
            ntfs_debug("bit 0x%x.", bit);
            /* If the bit is already set, go onto the next one. */
            if (*byte & bit) {
                lcn++;
                ntfs_debug("Continuing while loop 2.");
                continue;
            }
            /*
             * Allocate more memory if needed, including space for
             * the terminator element.
             * ntfs_malloc_nofs() operates on whole pages only.
             */
            if ((rlpos + 2) * sizeof(*rl) > rlsize) {
                runlist_element *rl2;

                ntfs_debug("Reallocating memory.");
                if (!rl)
                    ntfs_debug("First free bit is at LCN "
                            "0x%llx.",
                            (unsigned long long)
                            (lcn + bmp_pos));
                rl2 = ntfs_malloc_nofs(rlsize + (int)PAGE_SIZE);
                if (unlikely(!rl2)) {
                    err = -ENOMEM;
                    ntfs_error(vol->sb, "Failed to "
                            "allocate memory.");
                    goto out;
                }
                memcpy(rl2, rl, rlsize);
                ntfs_free(rl);
                rl = rl2;
                rlsize += PAGE_SIZE;
                ntfs_debug("Reallocated memory, rlsize 0x%x.",
                        rlsize);
            }
            /* Allocate the bitmap bit. */
            *byte |= bit;
            /* We need to write this bitmap page to disk. */
            need_writeback = 1;
            ntfs_debug("*byte 0x%x, need_writeback is set.",
                    (unsigned int)*byte);
            /*
             * Coalesce with previous run if adjacent LCNs.
             * Otherwise, append a new run.
             */
            ntfs_debug("Adding run (lcn 0x%llx, len 0x%llx), "
                    "prev_lcn 0x%llx, lcn 0x%llx, "
                    "bmp_pos 0x%llx, prev_run_len 0x%llx, "
                    "rlpos %i.",
                    (unsigned long long)(lcn + bmp_pos),
                    1ULL, (unsigned long long)prev_lcn,
                    (unsigned long long)lcn,
                    (unsigned long long)bmp_pos,
                    (unsigned long long)prev_run_len,
                    rlpos);
            if (prev_lcn == lcn + bmp_pos - prev_run_len && rlpos) {
                ntfs_debug("Coalescing to run (lcn 0x%llx, "
                        "len 0x%llx).",
                        (unsigned long long)
                        rl[rlpos - 1].lcn,
                        (unsigned long long)
                        rl[rlpos - 1].length);
                rl[rlpos - 1].length = ++prev_run_len;
                ntfs_debug("Run now (lcn 0x%llx, len 0x%llx), "
                        "prev_run_len 0x%llx.",
                        (unsigned long long)
                        rl[rlpos - 1].lcn,
                        (unsigned long long)
                        rl[rlpos - 1].length,
                        (unsigned long long)
                        prev_run_len);
            } else {
                if (likely(rlpos)) {
                    ntfs_debug("Adding new run, (previous "
                            "run lcn 0x%llx, "
                            "len 0x%llx).",
                            (unsigned long long)
                            rl[rlpos - 1].lcn,
                            (unsigned long long)
                            rl[rlpos - 1].length);
                    rl[rlpos].vcn = rl[rlpos - 1].vcn +
                            prev_run_len;
                } else {
                    ntfs_debug("Adding new run, is first "
                            "run.");
                    rl[rlpos].vcn = start_vcn;
                }
                rl[rlpos].lcn = prev_lcn = lcn + bmp_pos;
                rl[rlpos].length = prev_run_len = 1;
                rlpos++;
            }
            /* Done? */
            if (!--clusters) {
                LCN tc;
                /*
                 * Update the current zone position.  Positions
                 * of already scanned zones have been updated
                 * during the respective zone switches.
                 */
                tc = lcn + bmp_pos + 1;
                ntfs_debug("Done. Updating current zone "
                        "position, tc 0x%llx, "
                        "search_zone %i.",
                        (unsigned long long)tc,
                        search_zone);
                switch (search_zone) {
                case 1:
                    ntfs_debug("Before checks, "
                            "vol->mft_zone_pos "
                            "0x%llx.",
                            (unsigned long long)
                            vol->mft_zone_pos);
                    if (tc >= vol->mft_zone_end) {
                        vol->mft_zone_pos =
                                vol->mft_lcn;
                        if (!vol->mft_zone_end)
                            vol->mft_zone_pos = 0;
                    } else if ((bmp_initial_pos >=
                            vol->mft_zone_pos ||
                            tc > vol->mft_zone_pos)
                            && tc >= vol->mft_lcn)
                        vol->mft_zone_pos = tc;
                    ntfs_debug("After checks, "
                            "vol->mft_zone_pos "
                            "0x%llx.",
                            (unsigned long long)
                            vol->mft_zone_pos);
                    break;
                case 2:
                    ntfs_debug("Before checks, "
                            "vol->data1_zone_pos "
                            "0x%llx.",
                            (unsigned long long)
                            vol->data1_zone_pos);
                    if (tc >= vol->nr_clusters)
                        vol->data1_zone_pos =
                                 vol->mft_zone_end;
                    else if ((bmp_initial_pos >=
                            vol->data1_zone_pos ||
                            tc > vol->data1_zone_pos)
                            && tc >= vol->mft_zone_end)
                        vol->data1_zone_pos = tc;
                    ntfs_debug("After checks, "
                            "vol->data1_zone_pos "
                            "0x%llx.",
                            (unsigned long long)
                            vol->data1_zone_pos);
                    break;
                case 4:
                    ntfs_debug("Before checks, "
                            "vol->data2_zone_pos "
                            "0x%llx.",
                            (unsigned long long)
                            vol->data2_zone_pos);
                    if (tc >= vol->mft_zone_start)
                        vol->data2_zone_pos = 0;
                    else if (bmp_initial_pos >=
                              vol->data2_zone_pos ||
                              tc > vol->data2_zone_pos)
                        vol->data2_zone_pos = tc;
                    ntfs_debug("After checks, "
                            "vol->data2_zone_pos "
                            "0x%llx.",
                            (unsigned long long)
                            vol->data2_zone_pos);
                    break;
                default:
                    BUG();
                }
                ntfs_debug("Finished.  Going to out.");
                goto out;
            }
            lcn++;
        }
        bmp_pos += buf_size;
        ntfs_debug("After inner while loop: buf_size 0x%x, lcn "
                "0x%llx, bmp_pos 0x%llx, need_writeback %i.",
                buf_size, (unsigned long long)lcn,
                (unsigned long long)bmp_pos, need_writeback);
        if (bmp_pos < zone_end) {
            ntfs_debug("Continuing outer while loop, "
                    "bmp_pos 0x%llx, zone_end 0x%llx.",
                    (unsigned long long)bmp_pos,
                    (unsigned long long)zone_end);
            continue;
        }
zone_pass_done: /* Finished with the current zone pass. */
        ntfs_debug("At zone_pass_done, pass %i.", pass);
        if (pass == 1) {
            /*
             * Now do pass 2, scanning the first part of the zone
             * we omitted in pass 1.
             */
            pass = 2;
            zone_end = zone_start;
            switch (search_zone) {
            case 1: /* mft_zone */
                zone_start = vol->mft_zone_start;
                break;
            case 2: /* data1_zone */
                zone_start = vol->mft_zone_end;
                break;
            case 4: /* data2_zone */
                zone_start = 0;
                break;
            default:
                BUG();
            }
            /* Sanity check. */
            if (zone_end < zone_start)
                zone_end = zone_start;
            bmp_pos = zone_start;
            ntfs_debug("Continuing outer while loop, pass 2, "
                    "zone_start 0x%llx, zone_end 0x%llx, "
                    "bmp_pos 0x%llx.",
                    (unsigned long long)zone_start,
                    (unsigned long long)zone_end,
                    (unsigned long long)bmp_pos);
            continue;
        } /* pass == 2 */
done_zones_check:
        ntfs_debug("At done_zones_check, search_zone %i, done_zones "
                "before 0x%x, done_zones after 0x%x.",
                search_zone, done_zones,
                done_zones | search_zone);
        done_zones |= search_zone;
        if (done_zones < 7) {
            ntfs_debug("Switching zone.");
            /* Now switch to the next zone we haven't done yet. */
            pass = 1;
            switch (search_zone) {
            case 1:
                ntfs_debug("Switching from mft zone to data1 "
                        "zone.");
                /* Update mft zone position. */
                if (rlpos) {
                    LCN tc;

                    ntfs_debug("Before checks, "
                            "vol->mft_zone_pos "
                            "0x%llx.",
                            (unsigned long long)
                            vol->mft_zone_pos);
                    tc = rl[rlpos - 1].lcn +
                            rl[rlpos - 1].length;
                    if (tc >= vol->mft_zone_end) {
                        vol->mft_zone_pos =
                                vol->mft_lcn;
                        if (!vol->mft_zone_end)
                            vol->mft_zone_pos = 0;
                    } else if ((bmp_initial_pos >=
                            vol->mft_zone_pos ||
                            tc > vol->mft_zone_pos)
                            && tc >= vol->mft_lcn)
                        vol->mft_zone_pos = tc;
                    ntfs_debug("After checks, "
                            "vol->mft_zone_pos "
                            "0x%llx.",
                            (unsigned long long)
                            vol->mft_zone_pos);
                }
                /* Switch from mft zone to data1 zone. */
switch_to_data1_zone:       search_zone = 2;
                zone_start = bmp_initial_pos =
                        vol->data1_zone_pos;
                zone_end = vol->nr_clusters;
                if (zone_start == vol->mft_zone_end)
                    pass = 2;
                if (zone_start >= zone_end) {
                    vol->data1_zone_pos = zone_start =
                            vol->mft_zone_end;
                    pass = 2;
                }
                break;
            case 2:
                ntfs_debug("Switching from data1 zone to "
                        "data2 zone.");
                /* Update data1 zone position. */
                if (rlpos) {
                    LCN tc;

                    ntfs_debug("Before checks, "
                            "vol->data1_zone_pos "
                            "0x%llx.",
                            (unsigned long long)
                            vol->data1_zone_pos);
                    tc = rl[rlpos - 1].lcn +
                            rl[rlpos - 1].length;
                    if (tc >= vol->nr_clusters)
                        vol->data1_zone_pos =
                                 vol->mft_zone_end;
                    else if ((bmp_initial_pos >=
                            vol->data1_zone_pos ||
                            tc > vol->data1_zone_pos)
                            && tc >= vol->mft_zone_end)
                        vol->data1_zone_pos = tc;
                    ntfs_debug("After checks, "
                            "vol->data1_zone_pos "
                            "0x%llx.",
                            (unsigned long long)
                            vol->data1_zone_pos);
                }
                /* Switch from data1 zone to data2 zone. */
                search_zone = 4;
                zone_start = bmp_initial_pos =
                        vol->data2_zone_pos;
                zone_end = vol->mft_zone_start;
                if (!zone_start)
                    pass = 2;
                if (zone_start >= zone_end) {
                    vol->data2_zone_pos = zone_start =
                            bmp_initial_pos = 0;
                    pass = 2;
                }
                break;
            case 4:
                ntfs_debug("Switching from data2 zone to "
                        "data1 zone.");
                /* Update data2 zone position. */
                if (rlpos) {
                    LCN tc;

                    ntfs_debug("Before checks, "
                            "vol->data2_zone_pos "
                            "0x%llx.",
                            (unsigned long long)
                            vol->data2_zone_pos);
                    tc = rl[rlpos - 1].lcn +
                            rl[rlpos - 1].length;
                    if (tc >= vol->mft_zone_start)
                        vol->data2_zone_pos = 0;
                    else if (bmp_initial_pos >=
                              vol->data2_zone_pos ||
                              tc > vol->data2_zone_pos)
                        vol->data2_zone_pos = tc;
                    ntfs_debug("After checks, "
                            "vol->data2_zone_pos "
                            "0x%llx.",
                            (unsigned long long)
                            vol->data2_zone_pos);
                }
                /* Switch from data2 zone to data1 zone. */
                goto switch_to_data1_zone;
            default:
                BUG();
            }
            ntfs_debug("After zone switch, search_zone %i, "
                    "pass %i, bmp_initial_pos 0x%llx, "
                    "zone_start 0x%llx, zone_end 0x%llx.",
                    search_zone, pass,
                    (unsigned long long)bmp_initial_pos,
                    (unsigned long long)zone_start,
                    (unsigned long long)zone_end);
            bmp_pos = zone_start;
            if (zone_start == zone_end) {
                ntfs_debug("Empty zone, going to "
                        "done_zones_check.");
                /* Empty zone. Don't bother searching it. */
                goto done_zones_check;
            }
            ntfs_debug("Continuing outer while loop.");
            continue;
        } /* done_zones == 7 */
        ntfs_debug("All zones are finished.");
        /*
         * All zones are finished!  If DATA_ZONE, shrink mft zone.  If
         * MFT_ZONE, we have really run out of space.
         */
        mft_zone_size = vol->mft_zone_end - vol->mft_zone_start;
        ntfs_debug("vol->mft_zone_start 0x%llx, vol->mft_zone_end "
                "0x%llx, mft_zone_size 0x%llx.",
                (unsigned long long)vol->mft_zone_start,
                (unsigned long long)vol->mft_zone_end,
                (unsigned long long)mft_zone_size);
        if (zone == MFT_ZONE || mft_zone_size <= 0) {
            ntfs_debug("No free clusters left, going to out.");
            /* Really no more space left on device. */
            err = -ENOSPC;
            goto out;
        } /* zone == DATA_ZONE && mft_zone_size > 0 */
        ntfs_debug("Shrinking mft zone.");
        zone_end = vol->mft_zone_end;
        mft_zone_size >>= 1;
        if (mft_zone_size > 0)
            vol->mft_zone_end = vol->mft_zone_start + mft_zone_size;
        else /* mft zone and data2 zone no longer exist. */
            vol->data2_zone_pos = vol->mft_zone_start =
                    vol->mft_zone_end = 0;
        if (vol->mft_zone_pos >= vol->mft_zone_end) {
            vol->mft_zone_pos = vol->mft_lcn;
            if (!vol->mft_zone_end)
                vol->mft_zone_pos = 0;
        }
        bmp_pos = zone_start = bmp_initial_pos =
                vol->data1_zone_pos = vol->mft_zone_end;
        search_zone = 2;
        pass = 2;
        done_zones &= ~2;
        ntfs_debug("After shrinking mft zone, mft_zone_size 0x%llx, "
                "vol->mft_zone_start 0x%llx, "
                "vol->mft_zone_end 0x%llx, "
                "vol->mft_zone_pos 0x%llx, search_zone 2, "
                "pass 2, dones_zones 0x%x, zone_start 0x%llx, "
                "zone_end 0x%llx, vol->data1_zone_pos 0x%llx, "
                "continuing outer while loop.",
                (unsigned long long)mft_zone_size,
                (unsigned long long)vol->mft_zone_start,
                (unsigned long long)vol->mft_zone_end,
                (unsigned long long)vol->mft_zone_pos,
                done_zones, (unsigned long long)zone_start,
                (unsigned long long)zone_end,
                (unsigned long long)vol->data1_zone_pos);
    }
    ntfs_debug("After outer while loop.");
out:
    ntfs_debug("At out.");
    /* Add runlist terminator element. */
    if (likely(rl)) {
        rl[rlpos].vcn = rl[rlpos - 1].vcn + rl[rlpos - 1].length;
        rl[rlpos].lcn = is_extension ? LCN_ENOENT : LCN_RL_NOT_MAPPED;
        rl[rlpos].length = 0;
    }
    if (likely(page && !IS_ERR(page))) {
        if (need_writeback) {
            ntfs_debug("Marking page dirty.");
            flush_dcache_page(page);
            set_page_dirty(page);
            need_writeback = 0;
        }
        ntfs_unmap_page(page);
    }
    if (likely(!err)) {
        up_write(&vol->lcnbmp_lock);
        ntfs_debug("Done.");
        return rl;
    }
    ntfs_error(vol->sb, "Failed to allocate clusters, aborting "
            "(error %i).", err);
    if (rl) {
        int err2;

        if (err == -ENOSPC)
            ntfs_debug("Not enough space to complete allocation, "
                    "err -ENOSPC, first free lcn 0x%llx, "
                    "could allocate up to 0x%llx "
                    "clusters.",
                    (unsigned long long)rl[0].lcn,
                    (unsigned long long)(count - clusters));
        /* Deallocate all allocated clusters. */
        ntfs_debug("Attempting rollback...");
        err2 = ntfs_cluster_free_from_rl_nolock(vol, rl);
        if (err2) {
            ntfs_error(vol->sb, "Failed to rollback (error %i).  "
                    "Leaving inconsistent metadata!  "
                    "Unmount and run chkdsk.", err2);
            NVolSetErrors(vol);
        }
        /* Free the runlist. */
        ntfs_free(rl);
    } else if (err == -ENOSPC)
        ntfs_debug("No space left at all, err = -ENOSPC, first free "
                "lcn = 0x%llx.",
                (long long)vol->data1_zone_pos);
    up_write(&vol->lcnbmp_lock);
    return ERR_PTR(err);
}

s64 __ntfs_cluster_free(ntfs_inode *ni, const VCN start_vcn, s64 count,
        ntfs_attr_search_ctx *ctx, const bool is_rollback)
{
    s64 delta, to_free, total_freed, real_freed;
    ntfs_volume *vol;
    struct inode *lcnbmp_vi;
    runlist_element *rl;
    int err;

    BUG_ON(!ni);
    ntfs_debug("Entering for i_ino 0x%lx, start_vcn 0x%llx, count "
            "0x%llx.%s", ni->mft_no, (unsigned long long)start_vcn,
            (unsigned long long)count,
            is_rollback ? " (rollback)" : "");
    vol = ni->vol;
    lcnbmp_vi = vol->lcnbmp_ino;
    BUG_ON(!lcnbmp_vi);
    BUG_ON(start_vcn < 0);
    BUG_ON(count < -1);
    /*
     * Lock the lcn bitmap for writing but only if not rolling back.  We
     * must hold the lock all the way including through rollback otherwise
     * rollback is not possible because once we have cleared a bit and
     * dropped the lock, anyone could have set the bit again, thus
     * allocating the cluster for another use.
     */
    if (likely(!is_rollback))
        down_write(&vol->lcnbmp_lock);

    total_freed = real_freed = 0;

    rl = ntfs_attr_find_vcn_nolock(ni, start_vcn, ctx);
    if (IS_ERR(rl)) {
        if (!is_rollback)
            ntfs_error(vol->sb, "Failed to find first runlist "
                    "element (error %li), aborting.",
                    PTR_ERR(rl));
        err = PTR_ERR(rl);
        goto err_out;
    }
    if (unlikely(rl->lcn < LCN_HOLE)) {
        if (!is_rollback)
            ntfs_error(vol->sb, "First runlist element has "
                    "invalid lcn, aborting.");
        err = -EIO;
        goto err_out;
    }
    /* Find the starting cluster inside the run that needs freeing. */
    delta = start_vcn - rl->vcn;

    /* The number of clusters in this run that need freeing. */
    to_free = rl->length - delta;
    if (count >= 0 && to_free > count)
        to_free = count;

    if (likely(rl->lcn >= 0)) {
        /* Do the actual freeing of the clusters in this run. */
        err = ntfs_bitmap_set_bits_in_run(lcnbmp_vi, rl->lcn + delta,
                to_free, likely(!is_rollback) ? 0 : 1);
        if (unlikely(err)) {
            if (!is_rollback)
                ntfs_error(vol->sb, "Failed to clear first run "
                        "(error %i), aborting.", err);
            goto err_out;
        }
        /* We have freed @to_free real clusters. */
        real_freed = to_free;
    };
    /* Go to the next run and adjust the number of clusters left to free. */
    ++rl;
    if (count >= 0)
        count -= to_free;

    /* Keep track of the total "freed" clusters, including sparse ones. */
    total_freed = to_free;
    /*
     * Loop over the remaining runs, using @count as a capping value, and
     * free them.
     */
    for (; rl->length && count != 0; ++rl) {
        if (unlikely(rl->lcn < LCN_HOLE)) {
            VCN vcn;

            /* Attempt to map runlist. */
            vcn = rl->vcn;
            rl = ntfs_attr_find_vcn_nolock(ni, vcn, ctx);
            if (IS_ERR(rl)) {
                err = PTR_ERR(rl);
                if (!is_rollback)
                    ntfs_error(vol->sb, "Failed to map "
                            "runlist fragment or "
                            "failed to find "
                            "subsequent runlist "
                            "element.");
                goto err_out;
            }
            if (unlikely(rl->lcn < LCN_HOLE)) {
                if (!is_rollback)
                    ntfs_error(vol->sb, "Runlist element "
                            "has invalid lcn "
                            "(0x%llx).",
                            (unsigned long long)
                            rl->lcn);
                err = -EIO;
                goto err_out;
            }
        }
        /* The number of clusters in this run that need freeing. */
        to_free = rl->length;
        if (count >= 0 && to_free > count)
            to_free = count;

        if (likely(rl->lcn >= 0)) {
            /* Do the actual freeing of the clusters in the run. */
            err = ntfs_bitmap_set_bits_in_run(lcnbmp_vi, rl->lcn,
                    to_free, likely(!is_rollback) ? 0 : 1);
            if (unlikely(err)) {
                if (!is_rollback)
                    ntfs_error(vol->sb, "Failed to clear "
                            "subsequent run.");
                goto err_out;
            }
            /* We have freed @to_free real clusters. */
            real_freed += to_free;
        }
        /* Adjust the number of clusters left to free. */
        if (count >= 0)
            count -= to_free;
    
        /* Update the total done clusters. */
        total_freed += to_free;
    }
    if (likely(!is_rollback))
        up_write(&vol->lcnbmp_lock);

    BUG_ON(count > 0);

    /* We are done.  Return the number of actually freed clusters. */
    ntfs_debug("Done.");
    return real_freed;
err_out:
    if (is_rollback)
        return err;
    /* If no real clusters were freed, no need to rollback. */
    if (!real_freed) {
        up_write(&vol->lcnbmp_lock);
        return err;
    }
    /*
     * Attempt to rollback and if that succeeds just return the error code.
     * If rollback fails, set the volume errors flag, emit an error
     * message, and return the error code.
     */
    delta = __ntfs_cluster_free(ni, start_vcn, total_freed, ctx, true);
    if (delta < 0) {
        ntfs_error(vol->sb, "Failed to rollback (error %i).  Leaving "
                "inconsistent metadata!  Unmount and run "
                "chkdsk.", (int)delta);
        NVolSetErrors(vol);
    }
    up_write(&vol->lcnbmp_lock);
    ntfs_error(vol->sb, "Aborting (error %i).", err);
    return err;
}

#endif /* NTFS_RW */