This adds bitmap

Signed-off-by: Konstantin Komarov <almaz.alexandrov...@paragon-software.com>
---
 fs/ntfs3/bitfunc.c |  135 ++++
 fs/ntfs3/bitmap.c  | 1495 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 1630 insertions(+)
 create mode 100644 fs/ntfs3/bitfunc.c
 create mode 100644 fs/ntfs3/bitmap.c

diff --git a/fs/ntfs3/bitfunc.c b/fs/ntfs3/bitfunc.c
new file mode 100644
index 000000000000..2de5faef2721
--- /dev/null
+++ b/fs/ntfs3/bitfunc.c
@@ -0,0 +1,135 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *
+ * Copyright (C) 2019-2021 Paragon Software GmbH, All rights reserved.
+ *
+ */
+#include <linux/blkdev.h>
+#include <linux/buffer_head.h>
+#include <linux/fs.h>
+#include <linux/nls.h>
+
+#include "debug.h"
+#include "ntfs.h"
+#include "ntfs_fs.h"
+
+#define BITS_IN_SIZE_T (sizeof(size_t) * 8)
+
+/*
+ * fill_mask[i] - first i bits are '1' , i = 0,1,2,3,4,5,6,7,8
+ * fill_mask[i] = 0xFF >> (8-i)
+ */
+static const u8 fill_mask[] = { 0x00, 0x01, 0x03, 0x07, 0x0F,
+                               0x1F, 0x3F, 0x7F, 0xFF };
+
+/*
+ * zero_mask[i] - first i bits are '0' , i = 0,1,2,3,4,5,6,7,8
+ * zero_mask[i] = 0xFF << i
+ */
+static const u8 zero_mask[] = { 0xFF, 0xFE, 0xFC, 0xF8, 0xF0,
+                               0xE0, 0xC0, 0x80, 0x00 };
+
+/*
+ * are_bits_clear
+ *
+ * Returns true if all bits [bit, bit+nbits) are zeros "0"
+ */
+bool are_bits_clear(const ulong *lmap, size_t bit, size_t nbits)
+{
+       size_t pos = bit & 7;
+       const u8 *map = (u8 *)lmap + (bit >> 3);
+
+       if (pos) {
+               if (8 - pos >= nbits)
+                       return !nbits || !(*map & fill_mask[pos + nbits] &
+                                          zero_mask[pos]);
+
+               if (*map++ & zero_mask[pos])
+                       return false;
+               nbits -= 8 - pos;
+       }
+
+       pos = ((size_t)map) & (sizeof(size_t) - 1);
+       if (pos) {
+               pos = sizeof(size_t) - pos;
+               if (nbits >= pos * 8) {
+                       for (nbits -= pos * 8; pos; pos--, map++) {
+                               if (*map)
+                                       return false;
+                       }
+               }
+       }
+
+       for (pos = nbits / BITS_IN_SIZE_T; pos; pos--, map += sizeof(size_t)) {
+               if (*((size_t *)map))
+                       return false;
+       }
+
+       for (pos = (nbits % BITS_IN_SIZE_T) >> 3; pos; pos--, map++) {
+               if (*map)
+                       return false;
+       }
+
+       pos = nbits & 7;
+       if (pos && (*map & fill_mask[pos]))
+               return false;
+
+       // All bits are zero
+       return true;
+}
+
+/*
+ * are_bits_set
+ *
+ * Returns true if all bits [bit, bit+nbits) are ones "1"
+ */
+bool are_bits_set(const ulong *lmap, size_t bit, size_t nbits)
+{
+       u8 mask;
+       size_t pos = bit & 7;
+       const u8 *map = (u8 *)lmap + (bit >> 3);
+
+       if (pos) {
+               if (8 - pos >= nbits) {
+                       mask = fill_mask[pos + nbits] & zero_mask[pos];
+                       return !nbits || (*map & mask) == mask;
+               }
+
+               mask = zero_mask[pos];
+               if ((*map++ & mask) != mask)
+                       return false;
+               nbits -= 8 - pos;
+       }
+
+       pos = ((size_t)map) & (sizeof(size_t) - 1);
+       if (pos) {
+               pos = sizeof(size_t) - pos;
+               if (nbits >= pos * 8) {
+                       for (nbits -= pos * 8; pos; pos--, map++) {
+                               if (*map != 0xFF)
+                                       return false;
+                       }
+               }
+       }
+
+       for (pos = nbits / BITS_IN_SIZE_T; pos; pos--, map += sizeof(size_t)) {
+               if (*((size_t *)map) != MINUS_ONE_T)
+                       return false;
+       }
+
+       for (pos = (nbits % BITS_IN_SIZE_T) >> 3; pos; pos--, map++) {
+               if (*map != 0xFF)
+                       return false;
+       }
+
+       pos = nbits & 7;
+       if (pos) {
+               u8 mask = fill_mask[pos];
+
+               if ((*map & mask) != mask)
+                       return false;
+       }
+
+       // All bits are ones
+       return true;
+}
diff --git a/fs/ntfs3/bitmap.c b/fs/ntfs3/bitmap.c
new file mode 100644
index 000000000000..b1f6d6b1767d
--- /dev/null
+++ b/fs/ntfs3/bitmap.c
@@ -0,0 +1,1495 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *
+ * Copyright (C) 2019-2021 Paragon Software GmbH, All rights reserved.
+ *
+ */
+
+#include <linux/blkdev.h>
+#include <linux/buffer_head.h>
+#include <linux/fs.h>
+#include <linux/nls.h>
+
+#include "debug.h"
+#include "ntfs.h"
+#include "ntfs_fs.h"
+
+struct rb_node_key {
+       struct rb_node node;
+       size_t key;
+};
+
+/*
+ * Tree is sorted by start (key)
+ */
+struct e_node {
+       struct rb_node_key start; /* Tree sorted by start */
+       struct rb_node_key count; /* Tree sorted by len*/
+};
+
+static int wnd_rescan(struct wnd_bitmap *wnd);
+static struct buffer_head *wnd_map(struct wnd_bitmap *wnd, size_t iw);
+static bool wnd_is_free_hlp(struct wnd_bitmap *wnd, size_t bit, size_t bits);
+
+static inline u32 wnd_bits(const struct wnd_bitmap *wnd, size_t i)
+{
+       return i + 1 == wnd->nwnd ? wnd->bits_last : wnd->sb->s_blocksize * 8;
+}
+
+/*
+ * b_pos + b_len - biggest fragment
+ * Scan range [wpos wbits) window 'buf'
+ * Returns -1 if not found
+ */
+static size_t wnd_scan(const ulong *buf, size_t wbit, u32 wpos, u32 wend,
+                      size_t to_alloc, size_t *prev_tail, size_t *b_pos,
+                      size_t *b_len)
+{
+       while (wpos < wend) {
+               size_t free_len;
+               u32 free_bits, end;
+               u32 used = find_next_zero_bit(buf, wend, wpos);
+
+               if (used >= wend) {
+                       if (*b_len < *prev_tail) {
+                               *b_pos = wbit - *prev_tail;
+                               *b_len = *prev_tail;
+                       }
+
+                       *prev_tail = 0;
+                       return -1;
+               }
+
+               if (used > wpos) {
+                       wpos = used;
+                       if (*b_len < *prev_tail) {
+                               *b_pos = wbit - *prev_tail;
+                               *b_len = *prev_tail;
+                       }
+
+                       *prev_tail = 0;
+               }
+
+               /*
+                * Now we have a fragment [wpos, wend) staring with 0
+                */
+               end = wpos + to_alloc - *prev_tail;
+               free_bits = find_next_bit(buf, min(end, wend), wpos);
+
+               free_len = *prev_tail + free_bits - wpos;
+
+               if (*b_len < free_len) {
+                       *b_pos = wbit + wpos - *prev_tail;
+                       *b_len = free_len;
+               }
+
+               if (free_len >= to_alloc)
+                       return wbit + wpos - *prev_tail;
+
+               if (free_bits >= wend) {
+                       *prev_tail += free_bits - wpos;
+                       return -1;
+               }
+
+               wpos = free_bits + 1;
+
+               *prev_tail = 0;
+       }
+
+       return -1;
+}
+
+/*
+ * wnd_close
+ *
+ *
+ */
+void wnd_close(struct wnd_bitmap *wnd)
+{
+       struct rb_node *node, *next;
+
+       ntfs_free(wnd->free_bits);
+       run_close(&wnd->run);
+
+       node = rb_first(&wnd->start_tree);
+
+       while (node) {
+               next = rb_next(node);
+               rb_erase(node, &wnd->start_tree);
+               ntfs_free(rb_entry(node, struct e_node, start.node));
+               node = next;
+       }
+}
+
+static struct rb_node *rb_lookup(struct rb_root *root, size_t v)
+{
+       struct rb_node **p = &root->rb_node;
+       struct rb_node *r = NULL;
+
+       while (*p) {
+               struct rb_node_key *k;
+
+               k = rb_entry(*p, struct rb_node_key, node);
+               if (v < k->key) {
+                       p = &(*p)->rb_left;
+               } else if (v > k->key) {
+                       r = &k->node;
+                       p = &(*p)->rb_right;
+               } else {
+                       return &k->node;
+               }
+       }
+
+       return r;
+}
+
+/*
+ * rb_insert_count
+ *
+ * Helper function to insert special kind of 'count' tree
+ */
+static inline bool rb_insert_count(struct rb_root *root, struct e_node *e)
+{
+       struct rb_node **p = &root->rb_node;
+       struct rb_node *parent = NULL;
+       size_t e_ckey = e->count.key;
+       size_t e_skey = e->start.key;
+
+       while (*p) {
+               struct e_node *k =
+                       rb_entry(parent = *p, struct e_node, count.node);
+
+               if (e_ckey > k->count.key) {
+                       p = &(*p)->rb_left;
+               } else if (e_ckey < k->count.key) {
+                       p = &(*p)->rb_right;
+               } else if (e_skey < k->start.key) {
+                       p = &(*p)->rb_left;
+               } else if (e_skey > k->start.key) {
+                       p = &(*p)->rb_right;
+               } else {
+                       WARN_ON(1);
+                       return false;
+               }
+       }
+
+       rb_link_node(&e->count.node, parent, p);
+       rb_insert_color(&e->count.node, root);
+       return true;
+}
+
+/*
+ * inline bool rb_insert_start
+ *
+ * Helper function to insert special kind of 'count' tree
+ */
+static inline bool rb_insert_start(struct rb_root *root, struct e_node *e)
+{
+       struct rb_node **p = &root->rb_node;
+       struct rb_node *parent = NULL;
+       size_t e_skey = e->start.key;
+
+       while (*p) {
+               struct e_node *k;
+
+               parent = *p;
+
+               k = rb_entry(parent, struct e_node, start.node);
+               if (e_skey < k->start.key) {
+                       p = &(*p)->rb_left;
+               } else if (e_skey > k->start.key) {
+                       p = &(*p)->rb_right;
+               } else {
+                       WARN_ON(1);
+                       return false;
+               }
+       }
+
+       rb_link_node(&e->start.node, parent, p);
+       rb_insert_color(&e->start.node, root);
+       return true;
+}
+
+#define NTFS_MAX_WND_EXTENTS (32u * 1024u)
+
+/*
+ * wnd_add_free_ext
+ *
+ * adds a new extent of free space
+ * build = 1 when building tree
+ */
+static void wnd_add_free_ext(struct wnd_bitmap *wnd, size_t bit, size_t len,
+                            bool build)
+{
+       struct e_node *e, *e0 = NULL;
+       size_t ib, end_in = bit + len;
+       struct rb_node *n;
+
+       if (build) {
+               /* Use extent_min to filter too short extents */
+               if (wnd->count >= NTFS_MAX_WND_EXTENTS &&
+                   len <= wnd->extent_min) {
+                       wnd->uptodated = -1;
+                       return;
+               }
+       } else {
+               /* Try to find extent before 'bit' */
+               n = rb_lookup(&wnd->start_tree, bit);
+
+               if (!n) {
+                       n = rb_first(&wnd->start_tree);
+               } else {
+                       e = rb_entry(n, struct e_node, start.node);
+                       n = rb_next(n);
+                       if (e->start.key + e->count.key == bit) {
+                               /* Remove left */
+                               bit = e->start.key;
+                               len += e->count.key;
+                               rb_erase(&e->start.node, &wnd->start_tree);
+                               rb_erase(&e->count.node, &wnd->count_tree);
+                               wnd->count -= 1;
+                               e0 = e;
+                       }
+               }
+
+               while (n) {
+                       size_t next_end;
+
+                       e = rb_entry(n, struct e_node, start.node);
+                       next_end = e->start.key + e->count.key;
+                       if (e->start.key > end_in)
+                               break;
+
+                       /* Remove right */
+                       n = rb_next(n);
+                       len += next_end - end_in;
+                       end_in = next_end;
+                       rb_erase(&e->start.node, &wnd->start_tree);
+                       rb_erase(&e->count.node, &wnd->count_tree);
+                       wnd->count -= 1;
+
+                       if (!e0)
+                               e0 = e;
+                       else
+                               ntfs_free(e);
+               }
+
+               if (wnd->uptodated != 1) {
+                       /* Check bits before 'bit' */
+                       ib = wnd->zone_bit == wnd->zone_end ||
+                                            bit < wnd->zone_end ?
+                                    0 :
+                                    wnd->zone_end;
+
+                       while (bit > ib && wnd_is_free_hlp(wnd, bit - 1, 1)) {
+                               bit -= 1;
+                               len += 1;
+                       }
+
+                       /* Check bits after 'end_in' */
+                       ib = wnd->zone_bit == wnd->zone_end ||
+                                            end_in > wnd->zone_bit ?
+                                    wnd->nbits :
+                                    wnd->zone_bit;
+
+                       while (end_in < ib && wnd_is_free_hlp(wnd, end_in, 1)) {
+                               end_in += 1;
+                               len += 1;
+                       }
+               }
+       }
+       /* Insert new fragment */
+       if (wnd->count >= NTFS_MAX_WND_EXTENTS) {
+               if (e0)
+                       ntfs_free(e0);
+
+               wnd->uptodated = -1;
+
+               /* Compare with smallest fragment */
+               n = rb_last(&wnd->count_tree);
+               e = rb_entry(n, struct e_node, count.node);
+               if (len <= e->count.key)
+                       goto out; /* Do not insert small fragments */
+
+               if (build) {
+                       struct e_node *e2;
+
+                       n = rb_prev(n);
+                       e2 = rb_entry(n, struct e_node, count.node);
+                       /* smallest fragment will be 'e2->count.key' */
+                       wnd->extent_min = e2->count.key;
+               }
+
+               /* Replace smallest fragment by new one */
+               rb_erase(&e->start.node, &wnd->start_tree);
+               rb_erase(&e->count.node, &wnd->count_tree);
+               wnd->count -= 1;
+       } else {
+               e = e0 ? e0 : ntfs_malloc(sizeof(struct e_node));
+               if (!e) {
+                       wnd->uptodated = -1;
+                       goto out;
+               }
+
+               if (build && len <= wnd->extent_min)
+                       wnd->extent_min = len;
+       }
+       e->start.key = bit;
+       e->count.key = len;
+       if (len > wnd->extent_max)
+               wnd->extent_max = len;
+
+       rb_insert_start(&wnd->start_tree, e);
+       rb_insert_count(&wnd->count_tree, e);
+       wnd->count += 1;
+
+out:;
+}
+
+/*
+ * wnd_remove_free_ext
+ *
+ * removes a run from the cached free space
+ */
+static void wnd_remove_free_ext(struct wnd_bitmap *wnd, size_t bit, size_t len)
+{
+       struct rb_node *n, *n3;
+       struct e_node *e, *e3;
+       size_t end_in = bit + len;
+       size_t end3, end, new_key, new_len, max_new_len;
+
+       /* Try to find extent before 'bit' */
+       n = rb_lookup(&wnd->start_tree, bit);
+
+       if (!n)
+               return;
+
+       e = rb_entry(n, struct e_node, start.node);
+       end = e->start.key + e->count.key;
+
+       new_key = new_len = 0;
+       len = e->count.key;
+
+       /* Range [bit,end_in) must be inside 'e' or outside 'e' and 'n' */
+       if (e->start.key > bit)
+               ;
+       else if (end_in <= end) {
+               /* Range [bit,end_in) inside 'e' */
+               new_key = end_in;
+               new_len = end - end_in;
+               len = bit - e->start.key;
+       } else if (bit > end) {
+               bool bmax = false;
+
+               n3 = rb_next(n);
+
+               while (n3) {
+                       e3 = rb_entry(n3, struct e_node, start.node);
+                       if (e3->start.key >= end_in)
+                               break;
+
+                       if (e3->count.key == wnd->extent_max)
+                               bmax = true;
+
+                       end3 = e3->start.key + e3->count.key;
+                       if (end3 > end_in) {
+                               e3->start.key = end_in;
+                               rb_erase(&e3->count.node, &wnd->count_tree);
+                               e3->count.key = end3 - end_in;
+                               rb_insert_count(&wnd->count_tree, e3);
+                               break;
+                       }
+
+                       n3 = rb_next(n3);
+                       rb_erase(&e3->start.node, &wnd->start_tree);
+                       rb_erase(&e3->count.node, &wnd->count_tree);
+                       wnd->count -= 1;
+                       ntfs_free(e3);
+               }
+               if (!bmax)
+                       return;
+               n3 = rb_first(&wnd->count_tree);
+               wnd->extent_max =
+                       n3 ? rb_entry(n3, struct e_node, count.node)->count.key 
:
+                            0;
+               return;
+       }
+
+       if (e->count.key != wnd->extent_max) {
+               ;
+       } else if (rb_prev(&e->count.node)) {
+               ;
+       } else {
+               n3 = rb_next(&e->count.node);
+               max_new_len = len > new_len ? len : new_len;
+               if (!n3) {
+                       wnd->extent_max = max_new_len;
+               } else {
+                       e3 = rb_entry(n3, struct e_node, count.node);
+                       wnd->extent_max = max(e3->count.key, max_new_len);
+               }
+       }
+
+       if (!len) {
+               if (new_len) {
+                       e->start.key = new_key;
+                       rb_erase(&e->count.node, &wnd->count_tree);
+                       e->count.key = new_len;
+                       rb_insert_count(&wnd->count_tree, e);
+               } else {
+                       rb_erase(&e->start.node, &wnd->start_tree);
+                       rb_erase(&e->count.node, &wnd->count_tree);
+                       wnd->count -= 1;
+                       ntfs_free(e);
+               }
+               goto out;
+       }
+       rb_erase(&e->count.node, &wnd->count_tree);
+       e->count.key = len;
+       rb_insert_count(&wnd->count_tree, e);
+
+       if (!new_len)
+               goto out;
+
+       if (wnd->count >= NTFS_MAX_WND_EXTENTS) {
+               wnd->uptodated = -1;
+
+               /* Get minimal extent */
+               e = rb_entry(rb_last(&wnd->count_tree), struct e_node,
+                            count.node);
+               if (e->count.key > new_len)
+                       goto out;
+
+               /* Replace minimum */
+               rb_erase(&e->start.node, &wnd->start_tree);
+               rb_erase(&e->count.node, &wnd->count_tree);
+               wnd->count -= 1;
+       } else {
+               e = ntfs_malloc(sizeof(struct e_node));
+               if (!e)
+                       wnd->uptodated = -1;
+       }
+
+       if (e) {
+               e->start.key = new_key;
+               e->count.key = new_len;
+               rb_insert_start(&wnd->start_tree, e);
+               rb_insert_count(&wnd->count_tree, e);
+               wnd->count += 1;
+       }
+
+out:
+       if (!wnd->count && 1 != wnd->uptodated)
+               wnd_rescan(wnd);
+}
+
+/*
+ * wnd_rescan
+ *
+ * Scan all bitmap. used while initialization.
+ */
+static int wnd_rescan(struct wnd_bitmap *wnd)
+{
+       int err = 0;
+       size_t prev_tail = 0;
+       struct super_block *sb = wnd->sb;
+       struct ntfs_sb_info *sbi = sb->s_fs_info;
+       u64 lbo, len = 0;
+       u32 blocksize = sb->s_blocksize;
+       u8 cluster_bits = sbi->cluster_bits;
+       u32 wbits = 8 * sb->s_blocksize;
+       u32 used, frb;
+       const ulong *buf;
+       size_t wpos, wbit, iw, vbo;
+       struct buffer_head *bh = NULL;
+       CLST lcn, clen;
+
+       wnd->uptodated = 0;
+       wnd->extent_max = 0;
+       wnd->extent_min = MINUS_ONE_T;
+       wnd->total_zeroes = 0;
+
+       vbo = 0;
+
+       for (iw = 0; iw < wnd->nwnd; iw++) {
+               if (iw + 1 == wnd->nwnd)
+                       wbits = wnd->bits_last;
+
+               if (wnd->inited) {
+                       if (!wnd->free_bits[iw]) {
+                               /* all ones */
+                               if (prev_tail) {
+                                       wnd_add_free_ext(wnd,
+                                                        vbo * 8 - prev_tail,
+                                                        prev_tail, true);
+                                       prev_tail = 0;
+                               }
+                               goto next_wnd;
+                       }
+                       if (wbits == wnd->free_bits[iw]) {
+                               /* all zeroes */
+                               prev_tail += wbits;
+                               wnd->total_zeroes += wbits;
+                               goto next_wnd;
+                       }
+               }
+
+               if (!len) {
+                       u32 off = vbo & sbi->cluster_mask;
+
+                       if (!run_lookup_entry(&wnd->run, vbo >> cluster_bits,
+                                             &lcn, &clen, NULL)) {
+                               err = -ENOENT;
+                               goto out;
+                       }
+
+                       lbo = ((u64)lcn << cluster_bits) + off;
+                       len = ((u64)clen << cluster_bits) - off;
+               }
+
+               bh = ntfs_bread(sb, lbo >> sb->s_blocksize_bits);
+               if (!bh) {
+                       err = -EIO;
+                       goto out;
+               }
+
+               buf = (ulong *)bh->b_data;
+
+               used = __bitmap_weight(buf, wbits);
+               if (used < wbits) {
+                       frb = wbits - used;
+                       wnd->free_bits[iw] = frb;
+                       wnd->total_zeroes += frb;
+               }
+
+               wpos = 0;
+               wbit = vbo * 8;
+
+               if (wbit + wbits > wnd->nbits)
+                       wbits = wnd->nbits - wbit;
+
+               do {
+                       used = find_next_zero_bit(buf, wbits, wpos);
+
+                       if (used > wpos && prev_tail) {
+                               wnd_add_free_ext(wnd, wbit + wpos - prev_tail,
+                                                prev_tail, true);
+                               prev_tail = 0;
+                       }
+
+                       wpos = used;
+
+                       if (wpos >= wbits) {
+                               /* No free blocks */
+                               prev_tail = 0;
+                               break;
+                       }
+
+                       frb = find_next_bit(buf, wbits, wpos);
+                       if (frb >= wbits) {
+                               /* keep last free block */
+                               prev_tail += frb - wpos;
+                               break;
+                       }
+
+                       wnd_add_free_ext(wnd, wbit + wpos - prev_tail,
+                                        frb + prev_tail - wpos, true);
+
+                       /* Skip free block and first '1' */
+                       wpos = frb + 1;
+                       /* Reset previous tail */
+                       prev_tail = 0;
+               } while (wpos < wbits);
+
+next_wnd:
+
+               if (bh)
+                       put_bh(bh);
+               bh = NULL;
+
+               vbo += blocksize;
+               if (len) {
+                       len -= blocksize;
+                       lbo += blocksize;
+               }
+       }
+
+       /* Add last block */
+       if (prev_tail)
+               wnd_add_free_ext(wnd, wnd->nbits - prev_tail, prev_tail, true);
+
+       /*
+        * Before init cycle wnd->uptodated was 0
+        * If any errors or limits occurs while initialization then
+        * wnd->uptodated will be -1
+        * If 'uptodated' is still 0 then Tree is really updated
+        */
+       if (!wnd->uptodated)
+               wnd->uptodated = 1;
+
+       if (wnd->zone_bit != wnd->zone_end) {
+               size_t zlen = wnd->zone_end - wnd->zone_bit;
+
+               wnd->zone_end = wnd->zone_bit;
+               wnd_zone_set(wnd, wnd->zone_bit, zlen);
+       }
+
+out:
+       return err;
+}
+
+/*
+ * wnd_init
+ */
+int wnd_init(struct wnd_bitmap *wnd, struct super_block *sb, size_t nbits)
+{
+       int err;
+       u32 blocksize = sb->s_blocksize;
+       u32 wbits = blocksize * 8;
+
+       init_rwsem(&wnd->rw_lock);
+
+       wnd->sb = sb;
+       wnd->nbits = nbits;
+       wnd->total_zeroes = nbits;
+       wnd->extent_max = MINUS_ONE_T;
+       wnd->zone_bit = wnd->zone_end = 0;
+       wnd->nwnd = bytes_to_block(sb, bitmap_size(nbits));
+       wnd->bits_last = nbits & (wbits - 1);
+       if (!wnd->bits_last)
+               wnd->bits_last = wbits;
+
+       wnd->free_bits = ntfs_zalloc(wnd->nwnd * sizeof(u16));
+       if (!wnd->free_bits)
+               return -ENOMEM;
+
+       err = wnd_rescan(wnd);
+       if (err)
+               return err;
+
+       wnd->inited = true;
+
+       return 0;
+}
+
+/*
+ * wnd_map
+ *
+ * call sb_bread for requested window
+ */
+static struct buffer_head *wnd_map(struct wnd_bitmap *wnd, size_t iw)
+{
+       size_t vbo;
+       CLST lcn, clen;
+       struct super_block *sb = wnd->sb;
+       struct ntfs_sb_info *sbi;
+       struct buffer_head *bh;
+       u64 lbo;
+
+       sbi = sb->s_fs_info;
+       vbo = (u64)iw << sb->s_blocksize_bits;
+
+       if (!run_lookup_entry(&wnd->run, vbo >> sbi->cluster_bits, &lcn, &clen,
+                             NULL)) {
+               return ERR_PTR(-ENOENT);
+       }
+
+       lbo = ((u64)lcn << sbi->cluster_bits) + (vbo & sbi->cluster_mask);
+
+       bh = ntfs_bread(wnd->sb, lbo >> sb->s_blocksize_bits);
+       if (!bh)
+               return ERR_PTR(-EIO);
+
+       return bh;
+}
+
+/*
+ * wnd_set_free
+ *
+ * Marks the bits range from bit to bit + bits as free
+ */
+int wnd_set_free(struct wnd_bitmap *wnd, size_t bit, size_t bits)
+{
+       int err = 0;
+       struct super_block *sb = wnd->sb;
+       size_t bits0 = bits;
+       u32 wbits = 8 * sb->s_blocksize;
+       size_t iw = bit >> (sb->s_blocksize_bits + 3);
+       u32 wbit = bit & (wbits - 1);
+       struct buffer_head *bh;
+
+       while (iw < wnd->nwnd && bits) {
+               u32 tail, op;
+               ulong *buf;
+
+               if (iw + 1 == wnd->nwnd)
+                       wbits = wnd->bits_last;
+
+               tail = wbits - wbit;
+               op = tail < bits ? tail : bits;
+
+               bh = wnd_map(wnd, iw);
+               if (IS_ERR(bh)) {
+                       err = PTR_ERR(bh);
+                       break;
+               }
+
+               buf = (ulong *)bh->b_data;
+
+               lock_buffer(bh);
+
+               __bitmap_clear(buf, wbit, op);
+
+               wnd->free_bits[iw] += op;
+
+               set_buffer_uptodate(bh);
+               mark_buffer_dirty(bh);
+               unlock_buffer(bh);
+               put_bh(bh);
+
+               wnd->total_zeroes += op;
+               bits -= op;
+               wbit = 0;
+               iw += 1;
+       }
+
+       wnd_add_free_ext(wnd, bit, bits0, false);
+
+       return err;
+}
+
+/*
+ * wnd_set_used
+ *
+ * Marks the bits range from bit to bit + bits as used
+ */
+int wnd_set_used(struct wnd_bitmap *wnd, size_t bit, size_t bits)
+{
+       int err = 0;
+       struct super_block *sb = wnd->sb;
+       size_t bits0 = bits;
+       size_t iw = bit >> (sb->s_blocksize_bits + 3);
+       u32 wbits = 8 * sb->s_blocksize;
+       u32 wbit = bit & (wbits - 1);
+       struct buffer_head *bh;
+
+       while (iw < wnd->nwnd && bits) {
+               u32 tail, op;
+               ulong *buf;
+
+               if (unlikely(iw + 1 == wnd->nwnd))
+                       wbits = wnd->bits_last;
+
+               tail = wbits - wbit;
+               op = tail < bits ? tail : bits;
+
+               bh = wnd_map(wnd, iw);
+               if (IS_ERR(bh)) {
+                       err = PTR_ERR(bh);
+                       break;
+               }
+               buf = (ulong *)bh->b_data;
+
+               lock_buffer(bh);
+
+               __bitmap_set(buf, wbit, op);
+               wnd->free_bits[iw] -= op;
+
+               set_buffer_uptodate(bh);
+               mark_buffer_dirty(bh);
+               unlock_buffer(bh);
+               put_bh(bh);
+
+               wnd->total_zeroes -= op;
+               bits -= op;
+               wbit = 0;
+               iw += 1;
+       }
+
+       if (!RB_EMPTY_ROOT(&wnd->start_tree))
+               wnd_remove_free_ext(wnd, bit, bits0);
+
+       return err;
+}
+
+/*
+ * wnd_is_free_hlp
+ *
+ * Returns true if all clusters [bit, bit+bits) are free (bitmap only)
+ */
+static bool wnd_is_free_hlp(struct wnd_bitmap *wnd, size_t bit, size_t bits)
+{
+       struct super_block *sb = wnd->sb;
+       size_t iw = bit >> (sb->s_blocksize_bits + 3);
+       u32 wbits = 8 * sb->s_blocksize;
+       u32 wbit = bit & (wbits - 1);
+
+       while (iw < wnd->nwnd && bits) {
+               u32 tail, op;
+
+               if (unlikely(iw + 1 == wnd->nwnd))
+                       wbits = wnd->bits_last;
+
+               tail = wbits - wbit;
+               op = tail < bits ? tail : bits;
+
+               if (wbits != wnd->free_bits[iw]) {
+                       bool ret;
+                       struct buffer_head *bh = wnd_map(wnd, iw);
+
+                       if (IS_ERR(bh))
+                               return false;
+
+                       ret = are_bits_clear((ulong *)bh->b_data, wbit, op);
+
+                       put_bh(bh);
+                       if (!ret)
+                               return false;
+               }
+
+               bits -= op;
+               wbit = 0;
+               iw += 1;
+       }
+
+       return true;
+}
+
+/*
+ * wnd_is_free
+ *
+ * Returns true if all clusters [bit, bit+bits) are free
+ */
+bool wnd_is_free(struct wnd_bitmap *wnd, size_t bit, size_t bits)
+{
+       bool ret;
+       struct rb_node *n;
+       size_t end;
+       struct e_node *e;
+
+       if (RB_EMPTY_ROOT(&wnd->start_tree))
+               goto use_wnd;
+
+       n = rb_lookup(&wnd->start_tree, bit);
+       if (!n)
+               goto use_wnd;
+
+       e = rb_entry(n, struct e_node, start.node);
+
+       end = e->start.key + e->count.key;
+
+       if (bit < end && bit + bits <= end)
+               return true;
+
+use_wnd:
+       ret = wnd_is_free_hlp(wnd, bit, bits);
+
+       return ret;
+}
+
+/*
+ * wnd_is_used
+ *
+ * Returns true if all clusters [bit, bit+bits) are used
+ */
+bool wnd_is_used(struct wnd_bitmap *wnd, size_t bit, size_t bits)
+{
+       bool ret = false;
+       struct super_block *sb = wnd->sb;
+       size_t iw = bit >> (sb->s_blocksize_bits + 3);
+       u32 wbits = 8 * sb->s_blocksize;
+       u32 wbit = bit & (wbits - 1);
+       size_t end;
+       struct rb_node *n;
+       struct e_node *e;
+
+       if (RB_EMPTY_ROOT(&wnd->start_tree))
+               goto use_wnd;
+
+       end = bit + bits;
+       n = rb_lookup(&wnd->start_tree, end - 1);
+       if (!n)
+               goto use_wnd;
+
+       e = rb_entry(n, struct e_node, start.node);
+       if (e->start.key + e->count.key > bit)
+               return false;
+
+use_wnd:
+       while (iw < wnd->nwnd && bits) {
+               u32 tail, op;
+
+               if (unlikely(iw + 1 == wnd->nwnd))
+                       wbits = wnd->bits_last;
+
+               tail = wbits - wbit;
+               op = tail < bits ? tail : bits;
+
+               if (wnd->free_bits[iw]) {
+                       bool ret;
+                       struct buffer_head *bh = wnd_map(wnd, iw);
+
+                       if (IS_ERR(bh))
+                               goto out;
+
+                       ret = are_bits_set((ulong *)bh->b_data, wbit, op);
+                       put_bh(bh);
+                       if (!ret)
+                               goto out;
+               }
+
+               bits -= op;
+               wbit = 0;
+               iw += 1;
+       }
+       ret = true;
+
+out:
+       return ret;
+}
+
+/*
+ * wnd_find
+ * - flags - BITMAP_FIND_XXX flags
+ *
+ * looks for free space
+ * Returns 0 if not found
+ */
+size_t wnd_find(struct wnd_bitmap *wnd, size_t to_alloc, size_t hint,
+               size_t flags, size_t *allocated)
+{
+       struct super_block *sb;
+       u32 wbits, wpos, wzbit, wzend;
+       size_t fnd, max_alloc, b_len, b_pos;
+       size_t iw, prev_tail, nwnd, wbit, ebit, zbit, zend;
+       size_t to_alloc0 = to_alloc;
+       const ulong *buf;
+       const struct e_node *e;
+       const struct rb_node *pr, *cr;
+       u8 log2_bits;
+       bool fbits_valid;
+       struct buffer_head *bh;
+
+       /* fast checking for available free space */
+       if (flags & BITMAP_FIND_FULL) {
+               size_t zeroes = wnd_zeroes(wnd);
+
+               zeroes -= wnd->zone_end - wnd->zone_bit;
+               if (zeroes < to_alloc0)
+                       goto no_space;
+
+               if (to_alloc0 > wnd->extent_max)
+                       goto no_space;
+       } else {
+               if (to_alloc > wnd->extent_max)
+                       to_alloc = wnd->extent_max;
+       }
+
+       if (wnd->zone_bit <= hint && hint < wnd->zone_end)
+               hint = wnd->zone_end;
+
+       max_alloc = wnd->nbits;
+       b_len = b_pos = 0;
+
+       if (hint >= max_alloc)
+               hint = 0;
+
+       if (RB_EMPTY_ROOT(&wnd->start_tree)) {
+               if (wnd->uptodated == 1) {
+                       /* extents tree is updated -> no free space */
+                       goto no_space;
+               }
+               goto scan_bitmap;
+       }
+
+       e = NULL;
+       if (!hint)
+               goto allocate_biggest;
+
+       /* Use hint: enumerate extents by start >= hint */
+       pr = NULL;
+       cr = wnd->start_tree.rb_node;
+
+       for (;;) {
+               e = rb_entry(cr, struct e_node, start.node);
+
+               if (e->start.key == hint)
+                       break;
+
+               if (e->start.key < hint) {
+                       pr = cr;
+                       cr = cr->rb_right;
+                       if (!cr)
+                               break;
+                       continue;
+               }
+
+               cr = cr->rb_left;
+               if (!cr) {
+                       e = pr ? rb_entry(pr, struct e_node, start.node) : NULL;
+                       break;
+               }
+       }
+
+       if (!e)
+               goto allocate_biggest;
+
+       if (e->start.key + e->count.key > hint) {
+               /* We have found extension with 'hint' inside */
+               size_t len = e->start.key + e->count.key - hint;
+
+               if (len >= to_alloc && hint + to_alloc <= max_alloc) {
+                       fnd = hint;
+                       goto found;
+               }
+
+               if (!(flags & BITMAP_FIND_FULL)) {
+                       if (len > to_alloc)
+                               len = to_alloc;
+
+                       if (hint + len <= max_alloc) {
+                               fnd = hint;
+                               to_alloc = len;
+                               goto found;
+                       }
+               }
+       }
+
+allocate_biggest:
+       /* Allocate from biggest free extent */
+       e = rb_entry(rb_first(&wnd->count_tree), struct e_node, count.node);
+       if (e->count.key != wnd->extent_max)
+               wnd->extent_max = e->count.key;
+
+       if (e->count.key < max_alloc) {
+               if (e->count.key >= to_alloc) {
+                       ;
+               } else if (flags & BITMAP_FIND_FULL) {
+                       if (e->count.key < to_alloc0) {
+                               /* Biggest free block is less then requested */
+                               goto no_space;
+                       }
+                       to_alloc = e->count.key;
+               } else if (-1 != wnd->uptodated) {
+                       to_alloc = e->count.key;
+               } else {
+                       /* Check if we can use more bits */
+                       size_t op, max_check;
+                       struct rb_root start_tree;
+
+                       memcpy(&start_tree, &wnd->start_tree,
+                              sizeof(struct rb_root));
+                       memset(&wnd->start_tree, 0, sizeof(struct rb_root));
+
+                       max_check = e->start.key + to_alloc;
+                       if (max_check > max_alloc)
+                               max_check = max_alloc;
+                       for (op = e->start.key + e->count.key; op < max_check;
+                            op++) {
+                               if (!wnd_is_free(wnd, op, 1))
+                                       break;
+                       }
+                       memcpy(&wnd->start_tree, &start_tree,
+                              sizeof(struct rb_root));
+                       to_alloc = op - e->start.key;
+               }
+
+               /* Prepare to return */
+               fnd = e->start.key;
+               if (e->start.key + to_alloc > max_alloc)
+                       to_alloc = max_alloc - e->start.key;
+               goto found;
+       }
+
+       if (wnd->uptodated == 1) {
+               /* extents tree is updated -> no free space */
+               goto no_space;
+       }
+
+       b_len = e->count.key;
+       b_pos = e->start.key;
+
+scan_bitmap:
+       sb = wnd->sb;
+       log2_bits = sb->s_blocksize_bits + 3;
+
+       /* At most two ranges [hint, max_alloc) + [0, hint) */
+Again:
+
+       /* TODO: optimize request for case nbits > wbits */
+       iw = hint >> log2_bits;
+       wbits = sb->s_blocksize * 8;
+       wpos = hint & (wbits - 1);
+       prev_tail = 0;
+       fbits_valid = true;
+
+       if (max_alloc == wnd->nbits) {
+               nwnd = wnd->nwnd;
+       } else {
+               size_t t = max_alloc + wbits - 1;
+
+               nwnd = likely(t > max_alloc) ? (t >> log2_bits) : wnd->nwnd;
+       }
+
+       /* Enumerate all windows */
+       for (; iw < nwnd; iw++) {
+               wbit = iw << log2_bits;
+
+               if (!wnd->free_bits[iw]) {
+                       if (prev_tail > b_len) {
+                               b_pos = wbit - prev_tail;
+                               b_len = prev_tail;
+                       }
+
+                       /* Skip full used window */
+                       prev_tail = 0;
+                       wpos = 0;
+                       continue;
+               }
+
+               if (unlikely(iw + 1 == nwnd)) {
+                       if (max_alloc == wnd->nbits) {
+                               wbits = wnd->bits_last;
+                       } else {
+                               size_t t = max_alloc & (wbits - 1);
+
+                               if (t) {
+                                       wbits = t;
+                                       fbits_valid = false;
+                               }
+                       }
+               }
+
+               if (wnd->zone_end > wnd->zone_bit) {
+                       ebit = wbit + wbits;
+                       zbit = max(wnd->zone_bit, wbit);
+                       zend = min(wnd->zone_end, ebit);
+
+                       /* Here we have a window [wbit, ebit) and zone [zbit, 
zend) */
+                       if (zend <= zbit) {
+                               /* Zone does not overlap window */
+                       } else {
+                               wzbit = zbit - wbit;
+                               wzend = zend - wbit;
+
+                               /* Zone overlaps window */
+                               if (wnd->free_bits[iw] == wzend - wzbit) {
+                                       prev_tail = 0;
+                                       wpos = 0;
+                                       continue;
+                               }
+
+                               /* Scan two ranges window: [wbit, zbit) and 
[zend, ebit) */
+                               bh = wnd_map(wnd, iw);
+
+                               if (IS_ERR(bh)) {
+                                       /* TODO: error */
+                                       prev_tail = 0;
+                                       wpos = 0;
+                                       continue;
+                               }
+
+                               buf = (ulong *)bh->b_data;
+
+                               /* Scan range [wbit, zbit) */
+                               if (wpos < wzbit) {
+                                       /* Scan range [wpos, zbit) */
+                                       fnd = wnd_scan(buf, wbit, wpos, wzbit,
+                                                      to_alloc, &prev_tail,
+                                                      &b_pos, &b_len);
+                                       if (fnd != MINUS_ONE_T) {
+                                               put_bh(bh);
+                                               goto found;
+                                       }
+                               }
+
+                               prev_tail = 0;
+
+                               /* Scan range [zend, ebit) */
+                               if (wzend < wbits) {
+                                       fnd = wnd_scan(buf, wbit,
+                                                      max(wzend, wpos), wbits,
+                                                      to_alloc, &prev_tail,
+                                                      &b_pos, &b_len);
+                                       if (fnd != MINUS_ONE_T) {
+                                               put_bh(bh);
+                                               goto found;
+                                       }
+                               }
+
+                               wpos = 0;
+                               put_bh(bh);
+                               continue;
+                       }
+               }
+
+               /* Current window does not overlap zone */
+               if (!wpos && fbits_valid && wnd->free_bits[iw] == wbits) {
+                       /* window is empty */
+                       if (prev_tail + wbits >= to_alloc) {
+                               fnd = wbit + wpos - prev_tail;
+                               goto found;
+                       }
+
+                       /* Increase 'prev_tail' and process next window */
+                       prev_tail += wbits;
+                       wpos = 0;
+                       continue;
+               }
+
+               /* read window */
+               bh = wnd_map(wnd, iw);
+               if (IS_ERR(bh)) {
+                       // TODO: error
+                       prev_tail = 0;
+                       wpos = 0;
+                       continue;
+               }
+
+               buf = (ulong *)bh->b_data;
+
+               /* Scan range [wpos, eBits) */
+               fnd = wnd_scan(buf, wbit, wpos, wbits, to_alloc, &prev_tail,
+                              &b_pos, &b_len);
+               put_bh(bh);
+               if (fnd != MINUS_ONE_T)
+                       goto found;
+       }
+
+       if (b_len < prev_tail) {
+               /* The last fragment */
+               b_len = prev_tail;
+               b_pos = max_alloc - prev_tail;
+       }
+
+       if (hint) {
+               /*
+                * We have scanned range [hint max_alloc)
+                * Prepare to scan range [0 hint + to_alloc)
+                */
+               size_t nextmax = hint + to_alloc;
+
+               if (likely(nextmax >= hint) && nextmax < max_alloc)
+                       max_alloc = nextmax;
+               hint = 0;
+               goto Again;
+       }
+
+       if (!b_len)
+               goto no_space;
+
+       wnd->extent_max = b_len;
+
+       if (flags & BITMAP_FIND_FULL)
+               goto no_space;
+
+       fnd = b_pos;
+       to_alloc = b_len;
+
+found:
+       if (flags & BITMAP_FIND_MARK_AS_USED) {
+               /* TODO optimize remove extent (pass 'e'?) */
+               if (wnd_set_used(wnd, fnd, to_alloc))
+                       goto no_space;
+       } else if (wnd->extent_max != MINUS_ONE_T &&
+                  to_alloc > wnd->extent_max) {
+               wnd->extent_max = to_alloc;
+       }
+
+       *allocated = fnd;
+       return to_alloc;
+
+no_space:
+       return 0;
+}
+
+/*
+ * wnd_extend
+ *
+ * Extend bitmap ($MFT bitmap)
+ */
+int wnd_extend(struct wnd_bitmap *wnd, size_t new_bits)
+{
+       int err;
+       struct super_block *sb = wnd->sb;
+       struct ntfs_sb_info *sbi = sb->s_fs_info;
+       u32 blocksize = sb->s_blocksize;
+       u32 wbits = blocksize * 8;
+       u32 b0, new_last;
+       size_t bits, iw, new_wnd;
+       size_t old_bits = wnd->nbits;
+       u16 *new_free;
+
+       if (new_bits <= old_bits)
+               return -EINVAL;
+
+       /* align to 8 byte boundary */
+       new_wnd = bytes_to_block(sb, bitmap_size(new_bits));
+       new_last = new_bits & (wbits - 1);
+       if (!new_last)
+               new_last = wbits;
+
+       if (new_wnd != wnd->nwnd) {
+               new_free = ntfs_malloc(new_wnd * sizeof(u16));
+               if (!new_free)
+                       return -ENOMEM;
+
+               if (new_free != wnd->free_bits)
+                       memcpy(new_free, wnd->free_bits,
+                              wnd->nwnd * sizeof(short));
+               memset(new_free + wnd->nwnd, 0,
+                      (new_wnd - wnd->nwnd) * sizeof(short));
+               ntfs_free(wnd->free_bits);
+               wnd->free_bits = new_free;
+       }
+
+       /* Zero bits [old_bits,new_bits) */
+       bits = new_bits - old_bits;
+       b0 = old_bits & (wbits - 1);
+
+       for (iw = old_bits >> (sb->s_blocksize_bits + 3); bits; iw += 1) {
+               u32 op;
+               size_t frb;
+               u64 vbo, lbo, bytes;
+               struct buffer_head *bh;
+               ulong *buf;
+
+               if (iw + 1 == new_wnd)
+                       wbits = new_last;
+
+               op = b0 + bits > wbits ? wbits - b0 : bits;
+               vbo = (u64)iw * blocksize;
+
+               err = ntfs_vbo_to_lbo(sbi, &wnd->run, vbo, &lbo, &bytes);
+               if (err)
+                       break;
+
+               bh = ntfs_bread(sb, lbo >> sb->s_blocksize_bits);
+               if (!bh)
+                       return -EIO;
+
+               lock_buffer(bh);
+               buf = (ulong *)bh->b_data;
+
+               __bitmap_clear(buf, b0, blocksize * 8 - b0);
+               frb = wbits - __bitmap_weight(buf, wbits);
+               wnd->total_zeroes += frb - wnd->free_bits[iw];
+               wnd->free_bits[iw] = frb;
+
+               set_buffer_uptodate(bh);
+               mark_buffer_dirty(bh);
+               unlock_buffer(bh);
+               /*err = sync_dirty_buffer(bh);*/
+
+               b0 = 0;
+               bits -= op;
+       }
+
+       wnd->nbits = new_bits;
+       wnd->nwnd = new_wnd;
+       wnd->bits_last = new_last;
+
+       wnd_add_free_ext(wnd, old_bits, new_bits - old_bits, false);
+
+       return 0;
+}
+
+/*
+ * wnd_zone_set
+ */
+void wnd_zone_set(struct wnd_bitmap *wnd, size_t lcn, size_t len)
+{
+       size_t zlen;
+
+       zlen = wnd->zone_end - wnd->zone_bit;
+       if (zlen)
+               wnd_add_free_ext(wnd, wnd->zone_bit, zlen, false);
+
+       if (!RB_EMPTY_ROOT(&wnd->start_tree) && len)
+               wnd_remove_free_ext(wnd, lcn, len);
+
+       wnd->zone_bit = lcn;
+       wnd->zone_end = lcn + len;
+}
+
+int ntfs_trim_fs(struct ntfs_sb_info *sbi, struct fstrim_range *range)
+{
+       int err = 0;
+       struct super_block *sb = sbi->sb;
+       struct wnd_bitmap *wnd = &sbi->used.bitmap;
+       u32 wbits = 8 * sb->s_blocksize;
+       CLST len = 0, lcn = 0, done = 0;
+       CLST minlen = bytes_to_cluster(sbi, range->minlen);
+       CLST lcn_from = bytes_to_cluster(sbi, range->start);
+       size_t iw = lcn_from >> (sb->s_blocksize_bits + 3);
+       u32 wbit = lcn_from & (wbits - 1);
+       const ulong *buf;
+       CLST lcn_to;
+
+       if (!minlen)
+               minlen = 1;
+
+       if (range->len == (u64)-1)
+               lcn_to = wnd->nbits;
+       else
+               lcn_to = bytes_to_cluster(sbi, range->start + range->len);
+
+       down_read_nested(&wnd->rw_lock, BITMAP_MUTEX_CLUSTERS);
+
+       for (; iw < wnd->nbits; iw++, wbit = 0) {
+               CLST lcn_wnd = iw * wbits;
+               struct buffer_head *bh;
+
+               if (lcn_wnd > lcn_to)
+                       break;
+
+               if (!wnd->free_bits[iw])
+                       continue;
+
+               if (iw + 1 == wnd->nwnd)
+                       wbits = wnd->bits_last;
+
+               if (lcn_wnd + wbits > lcn_to)
+                       wbits = lcn_to - lcn_wnd;
+
+               bh = wnd_map(wnd, iw);
+               if (IS_ERR(bh)) {
+                       err = PTR_ERR(bh);
+                       break;
+               }
+
+               buf = (ulong *)bh->b_data;
+
+               for (; wbit < wbits; wbit++) {
+                       if (!test_bit(wbit, buf)) {
+                               if (!len)
+                                       lcn = lcn_wnd + wbit;
+                               len += 1;
+                               continue;
+                       }
+                       if (len >= minlen) {
+                               err = ntfs_discard(sbi, lcn, len);
+                               if (err)
+                                       goto out;
+                               done += len;
+                       }
+                       len = 0;
+               }
+               put_bh(bh);
+       }
+
+       /* Process the last fragment */
+       if (len >= minlen) {
+               err = ntfs_discard(sbi, lcn, len);
+               if (err)
+                       goto out;
+               done += len;
+       }
+
+out:
+       range->len = (u64)done << sbi->cluster_bits;
+
+       up_read(&wnd->rw_lock);
+
+       return err;
+}
-- 
2.25.4

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