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run.c
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// SPDX-License-Identifier: GPL-2.0
/*
*
* Copyright (C) 2019-2021 Paragon Software GmbH, All rights reserved.
*
* TODO: try to use extents tree (instead of array)
*/
#include <linux/blkdev.h>
#include <linux/fs.h>
#include <linux/log2.h>
#include "debug.h"
#include "ntfs.h"
#include "ntfs_fs.h"
/* runs_tree is a continues memory. Try to avoid big size. */
#define NTFS3_RUN_MAX_BYTES 0x10000
struct ntfs_run {
CLST vcn; /* Virtual cluster number. */
CLST len; /* Length in clusters. */
CLST lcn; /* Logical cluster number. */
};
/*
* run_lookup - Lookup the index of a MCB entry that is first <= vcn.
*
* Case of success it will return non-zero value and set
* @index parameter to index of entry been found.
* Case of entry missing from list 'index' will be set to
* point to insertion position for the entry question.
*/
static bool run_lookup(const struct runs_tree *run, CLST vcn, size_t *index)
{
size_t min_idx, max_idx, mid_idx;
struct ntfs_run *r;
if (!run->count) {
*index = 0;
return false;
}
min_idx = 0;
max_idx = run->count - 1;
/* Check boundary cases specially, 'cause they cover the often requests. */
r = run->runs;
if (vcn < r->vcn) {
*index = 0;
return false;
}
if (vcn < r->vcn + r->len) {
*index = 0;
return true;
}
r += max_idx;
if (vcn >= r->vcn + r->len) {
*index = run->count;
return false;
}
if (vcn >= r->vcn) {
*index = max_idx;
return true;
}
do {
mid_idx = min_idx + ((max_idx - min_idx) >> 1);
r = run->runs + mid_idx;
if (vcn < r->vcn) {
max_idx = mid_idx - 1;
if (!mid_idx)
break;
} else if (vcn >= r->vcn + r->len) {
min_idx = mid_idx + 1;
} else {
*index = mid_idx;
return true;
}
} while (min_idx <= max_idx);
*index = max_idx + 1;
return false;
}
/*
* run_consolidate - Consolidate runs starting from a given one.
*/
static void run_consolidate(struct runs_tree *run, size_t index)
{
size_t i;
struct ntfs_run *r = run->runs + index;
while (index + 1 < run->count) {
/*
* I should merge current run with next
* if start of the next run lies inside one being tested.
*/
struct ntfs_run *n = r + 1;
CLST end = r->vcn + r->len;
CLST dl;
/* Stop if runs are not aligned one to another. */
if (n->vcn > end)
break;
dl = end - n->vcn;
/*
* If range at index overlaps with next one
* then I will either adjust it's start position
* or (if completely matches) dust remove one from the list.
*/
if (dl > 0) {
if (n->len <= dl)
goto remove_next_range;
n->len -= dl;
n->vcn += dl;
if (n->lcn != SPARSE_LCN)
n->lcn += dl;
dl = 0;
}
/*
* Stop if sparse mode does not match
* both current and next runs.
*/
if ((n->lcn == SPARSE_LCN) != (r->lcn == SPARSE_LCN)) {
index += 1;
r = n;
continue;
}
/*
* Check if volume block
* of a next run lcn does not match
* last volume block of the current run.
*/
if (n->lcn != SPARSE_LCN && n->lcn != r->lcn + r->len)
break;
/*
* Next and current are siblings.
* Eat/join.
*/
r->len += n->len - dl;
remove_next_range:
i = run->count - (index + 1);
if (i > 1)
memmove(n, n + 1, sizeof(*n) * (i - 1));
run->count -= 1;
}
}
/*
* run_is_mapped_full
*
* Return: True if range [svcn - evcn] is mapped.
*/
bool run_is_mapped_full(const struct runs_tree *run, CLST svcn, CLST evcn)
{
size_t i;
const struct ntfs_run *r, *end;
CLST next_vcn;
if (!run_lookup(run, svcn, &i))
return false;
end = run->runs + run->count;
r = run->runs + i;
for (;;) {
next_vcn = r->vcn + r->len;
if (next_vcn > evcn)
return true;
if (++r >= end)
return false;
if (r->vcn != next_vcn)
return false;
}
}
bool run_lookup_entry(const struct runs_tree *run, CLST vcn, CLST *lcn,
CLST *len, size_t *index)
{
size_t idx;
CLST gap;
struct ntfs_run *r;
/* Fail immediately if nrun was not touched yet. */
if (!run->runs)
return false;
if (!run_lookup(run, vcn, &idx))
return false;
r = run->runs + idx;
if (vcn >= r->vcn + r->len)
return false;
gap = vcn - r->vcn;
if (r->len <= gap)
return false;
*lcn = r->lcn == SPARSE_LCN ? SPARSE_LCN : (r->lcn + gap);
if (len)
*len = r->len - gap;
if (index)
*index = idx;
return true;
}
/*
* run_truncate_head - Decommit the range before vcn.
*/
void run_truncate_head(struct runs_tree *run, CLST vcn)
{
size_t index;
struct ntfs_run *r;
if (run_lookup(run, vcn, &index)) {
r = run->runs + index;
if (vcn > r->vcn) {
CLST dlen = vcn - r->vcn;
r->vcn = vcn;
r->len -= dlen;
if (r->lcn != SPARSE_LCN)
r->lcn += dlen;
}
if (!index)
return;
}
r = run->runs;
memmove(r, r + index, sizeof(*r) * (run->count - index));
run->count -= index;
if (!run->count) {
kvfree(run->runs);
run->runs = NULL;
run->allocated = 0;
}
}
/*
* run_truncate - Decommit the range after vcn.
*/
void run_truncate(struct runs_tree *run, CLST vcn)
{
size_t index;
/*
* If I hit the range then
* I have to truncate one.
* If range to be truncated is becoming empty
* then it will entirely be removed.
*/
if (run_lookup(run, vcn, &index)) {
struct ntfs_run *r = run->runs + index;
r->len = vcn - r->vcn;
if (r->len > 0)
index += 1;
}
/*
* At this point 'index' is set to position that
* should be thrown away (including index itself)
* Simple one - just set the limit.
*/
run->count = index;
/* Do not reallocate array 'runs'. Only free if possible. */
if (!index) {
kvfree(run->runs);
run->runs = NULL;
run->allocated = 0;
}
}
/*
* run_truncate_around - Trim head and tail if necessary.
*/
void run_truncate_around(struct runs_tree *run, CLST vcn)
{
run_truncate_head(run, vcn);
if (run->count >= NTFS3_RUN_MAX_BYTES / sizeof(struct ntfs_run) / 2)
run_truncate(run, (run->runs + (run->count >> 1))->vcn);
}
/*
* run_add_entry
*
* Sets location to known state.
* Run to be added may overlap with existing location.
*
* Return: false if of memory.
*/
bool run_add_entry(struct runs_tree *run, CLST vcn, CLST lcn, CLST len,
bool is_mft)
{
size_t used, index;
struct ntfs_run *r;
bool inrange;
CLST tail_vcn = 0, tail_len = 0, tail_lcn = 0;
bool should_add_tail = false;
/*
* Lookup the insertion point.
*
* Execute bsearch for the entry containing
* start position question.
*/
inrange = run_lookup(run, vcn, &index);
/*
* Shortcut here would be case of
* range not been found but one been added
* continues previous run.
* This case I can directly make use of
* existing range as my start point.
*/
if (!inrange && index > 0) {
struct ntfs_run *t = run->runs + index - 1;
if (t->vcn + t->len == vcn &&
(t->lcn == SPARSE_LCN) == (lcn == SPARSE_LCN) &&
(lcn == SPARSE_LCN || lcn == t->lcn + t->len)) {
inrange = true;
index -= 1;
}
}
/*
* At this point 'index' either points to the range
* containing start position or to the insertion position
* for a new range.
* So first let's check if range I'm probing is here already.
*/
if (!inrange) {
requires_new_range:
/*
* Range was not found.
* Insert at position 'index'
*/
used = run->count * sizeof(struct ntfs_run);
/*
* Check allocated space.
* If one is not enough to get one more entry
* then it will be reallocated.
*/
if (run->allocated < used + sizeof(struct ntfs_run)) {
size_t bytes;
struct ntfs_run *new_ptr;
/* Use power of 2 for 'bytes'. */
if (!used) {
bytes = 64;
} else if (used <= 16 * PAGE_SIZE) {
if (is_power_of_2(run->allocated))
bytes = run->allocated << 1;
else
bytes = (size_t)1
<< (2 + blksize_bits(used));
} else {
bytes = run->allocated + (16 * PAGE_SIZE);
}
WARN_ON(!is_mft && bytes > NTFS3_RUN_MAX_BYTES);
new_ptr = kvmalloc(bytes, GFP_KERNEL);
if (!new_ptr)
return false;
r = new_ptr + index;
memcpy(new_ptr, run->runs,
index * sizeof(struct ntfs_run));
memcpy(r + 1, run->runs + index,
sizeof(struct ntfs_run) * (run->count - index));
kvfree(run->runs);
run->runs = new_ptr;
run->allocated = bytes;
} else {
size_t i = run->count - index;
r = run->runs + index;
/* memmove appears to be a bottle neck here... */
if (i > 0)
memmove(r + 1, r, sizeof(struct ntfs_run) * i);
}
r->vcn = vcn;
r->lcn = lcn;
r->len = len;
run->count += 1;
} else {
r = run->runs + index;
/*
* If one of ranges was not allocated then we
* have to split location we just matched and
* insert current one.
* A common case this requires tail to be reinserted
* a recursive call.
*/
if (((lcn == SPARSE_LCN) != (r->lcn == SPARSE_LCN)) ||
(lcn != SPARSE_LCN && lcn != r->lcn + (vcn - r->vcn))) {
CLST to_eat = vcn - r->vcn;
CLST Tovcn = to_eat + len;
should_add_tail = Tovcn < r->len;
if (should_add_tail) {
tail_lcn = r->lcn == SPARSE_LCN
? SPARSE_LCN
: (r->lcn + Tovcn);
tail_vcn = r->vcn + Tovcn;
tail_len = r->len - Tovcn;
}
if (to_eat > 0) {
r->len = to_eat;
inrange = false;
index += 1;
goto requires_new_range;
}
/* lcn should match one were going to add. */
r->lcn = lcn;
}
/*
* If existing range fits then were done.
* Otherwise extend found one and fall back to range jocode.
*/
if (r->vcn + r->len < vcn + len)
r->len += len - ((r->vcn + r->len) - vcn);
}
/*
* And normalize it starting from insertion point.
* It's possible that no insertion needed case if
* start point lies within the range of an entry
* that 'index' points to.
*/
if (inrange && index > 0)
index -= 1;
run_consolidate(run, index);
run_consolidate(run, index + 1);
/*
* A special case.
* We have to add extra range a tail.
*/
if (should_add_tail &&
!run_add_entry(run, tail_vcn, tail_lcn, tail_len, is_mft))
return false;
return true;
}
/* run_collapse_range
*
* Helper for attr_collapse_range(),
* which is helper for fallocate(collapse_range).
*/
bool run_collapse_range(struct runs_tree *run, CLST vcn, CLST len)
{
size_t index, eat;
struct ntfs_run *r, *e, *eat_start, *eat_end;
CLST end;
if (WARN_ON(!run_lookup(run, vcn, &index)))
return true; /* Should never be here. */
e = run->runs + run->count;
r = run->runs + index;
end = vcn + len;
if (vcn > r->vcn) {
if (r->vcn + r->len <= end) {
/* Collapse tail of run .*/
r->len = vcn - r->vcn;
} else if (r->lcn == SPARSE_LCN) {
/* Collapse a middle part of sparsed run. */
r->len -= len;
} else {
/* Collapse a middle part of normal run, split. */
if (!run_add_entry(run, vcn, SPARSE_LCN, len, false))
return false;
return run_collapse_range(run, vcn, len);
}
r += 1;
}
eat_start = r;
eat_end = r;
for (; r < e; r++) {
CLST d;
if (r->vcn >= end) {
r->vcn -= len;
continue;
}
if (r->vcn + r->len <= end) {
/* Eat this run. */
eat_end = r + 1;
continue;
}
d = end - r->vcn;
if (r->lcn != SPARSE_LCN)
r->lcn += d;
r->len -= d;
r->vcn -= len - d;
}
eat = eat_end - eat_start;
memmove(eat_start, eat_end, (e - eat_end) * sizeof(*r));
run->count -= eat;
return true;
}
/* run_insert_range
*
* Helper for attr_insert_range(),
* which is helper for fallocate(insert_range).
*/
bool run_insert_range(struct runs_tree *run, CLST vcn, CLST len)
{
size_t index;
struct ntfs_run *r, *e;
if (WARN_ON(!run_lookup(run, vcn, &index)))
return false; /* Should never be here. */
e = run->runs + run->count;
r = run->runs + index;
if (vcn > r->vcn)
r += 1;
for (; r < e; r++)
r->vcn += len;
r = run->runs + index;
if (vcn > r->vcn) {
/* split fragment. */
CLST len1 = vcn - r->vcn;
CLST len2 = r->len - len1;
CLST lcn2 = r->lcn == SPARSE_LCN ? SPARSE_LCN : (r->lcn + len1);
r->len = len1;
if (!run_add_entry(run, vcn + len, lcn2, len2, false))
return false;
}
if (!run_add_entry(run, vcn, SPARSE_LCN, len, false))
return false;
return true;
}
/*
* run_get_entry - Return index-th mapped region.
*/
bool run_get_entry(const struct runs_tree *run, size_t index, CLST *vcn,
CLST *lcn, CLST *len)
{
const struct ntfs_run *r;
if (index >= run->count)
return false;
r = run->runs + index;
if (!r->len)
return false;
if (vcn)
*vcn = r->vcn;
if (lcn)
*lcn = r->lcn;
if (len)
*len = r->len;
return true;
}
/*
* run_packed_size - Calculate the size of packed int64.
*/
#ifdef __BIG_ENDIAN
static inline int run_packed_size(const s64 n)
{
const u8 *p = (const u8 *)&n + sizeof(n) - 1;
if (n >= 0) {
if (p[-7] || p[-6] || p[-5] || p[-4])
p -= 4;
if (p[-3] || p[-2])
p -= 2;
if (p[-1])
p -= 1;
if (p[0] & 0x80)
p -= 1;
} else {
if (p[-7] != 0xff || p[-6] != 0xff || p[-5] != 0xff ||
p[-4] != 0xff)
p -= 4;
if (p[-3] != 0xff || p[-2] != 0xff)
p -= 2;
if (p[-1] != 0xff)
p -= 1;
if (!(p[0] & 0x80))
p -= 1;
}
return (const u8 *)&n + sizeof(n) - p;
}
/* Full trusted function. It does not check 'size' for errors. */
static inline void run_pack_s64(u8 *run_buf, u8 size, s64 v)
{
const u8 *p = (u8 *)&v;
switch (size) {
case 8:
run_buf[7] = p[0];
fallthrough;
case 7:
run_buf[6] = p[1];
fallthrough;
case 6:
run_buf[5] = p[2];
fallthrough;
case 5:
run_buf[4] = p[3];
fallthrough;
case 4:
run_buf[3] = p[4];
fallthrough;
case 3:
run_buf[2] = p[5];
fallthrough;
case 2:
run_buf[1] = p[6];
fallthrough;
case 1:
run_buf[0] = p[7];
}
}
/* Full trusted function. It does not check 'size' for errors. */
static inline s64 run_unpack_s64(const u8 *run_buf, u8 size, s64 v)
{
u8 *p = (u8 *)&v;
switch (size) {
case 8:
p[0] = run_buf[7];
fallthrough;
case 7:
p[1] = run_buf[6];
fallthrough;
case 6:
p[2] = run_buf[5];
fallthrough;
case 5:
p[3] = run_buf[4];
fallthrough;
case 4:
p[4] = run_buf[3];
fallthrough;
case 3:
p[5] = run_buf[2];
fallthrough;
case 2:
p[6] = run_buf[1];
fallthrough;
case 1:
p[7] = run_buf[0];
}
return v;
}
#else
static inline int run_packed_size(const s64 n)
{
const u8 *p = (const u8 *)&n;
if (n >= 0) {
if (p[7] || p[6] || p[5] || p[4])
p += 4;
if (p[3] || p[2])
p += 2;
if (p[1])
p += 1;
if (p[0] & 0x80)
p += 1;
} else {
if (p[7] != 0xff || p[6] != 0xff || p[5] != 0xff ||
p[4] != 0xff)
p += 4;
if (p[3] != 0xff || p[2] != 0xff)
p += 2;
if (p[1] != 0xff)
p += 1;
if (!(p[0] & 0x80))
p += 1;
}
return 1 + p - (const u8 *)&n;
}
/* Full trusted function. It does not check 'size' for errors. */
static inline void run_pack_s64(u8 *run_buf, u8 size, s64 v)
{
const u8 *p = (u8 *)&v;
/* memcpy( run_buf, &v, size); Is it faster? */
switch (size) {
case 8:
run_buf[7] = p[7];
fallthrough;
case 7:
run_buf[6] = p[6];
fallthrough;
case 6:
run_buf[5] = p[5];
fallthrough;
case 5:
run_buf[4] = p[4];
fallthrough;
case 4:
run_buf[3] = p[3];
fallthrough;
case 3:
run_buf[2] = p[2];
fallthrough;
case 2:
run_buf[1] = p[1];
fallthrough;
case 1:
run_buf[0] = p[0];
}
}
/* full trusted function. It does not check 'size' for errors */
static inline s64 run_unpack_s64(const u8 *run_buf, u8 size, s64 v)
{
u8 *p = (u8 *)&v;
/* memcpy( &v, run_buf, size); Is it faster? */
switch (size) {
case 8:
p[7] = run_buf[7];
fallthrough;
case 7:
p[6] = run_buf[6];
fallthrough;
case 6:
p[5] = run_buf[5];
fallthrough;
case 5:
p[4] = run_buf[4];
fallthrough;
case 4:
p[3] = run_buf[3];
fallthrough;
case 3:
p[2] = run_buf[2];
fallthrough;
case 2:
p[1] = run_buf[1];
fallthrough;
case 1:
p[0] = run_buf[0];
}
return v;
}
#endif
/*
* run_pack - Pack runs into buffer.
*
* packed_vcns - How much runs we have packed.
* packed_size - How much bytes we have used run_buf.
*/
int run_pack(const struct runs_tree *run, CLST svcn, CLST len, u8 *run_buf,
u32 run_buf_size, CLST *packed_vcns)
{
CLST next_vcn, vcn, lcn;
CLST prev_lcn = 0;
CLST evcn1 = svcn + len;
const struct ntfs_run *r, *r_end;
int packed_size = 0;
size_t i;
s64 dlcn;
int offset_size, size_size, tmp;
*packed_vcns = 0;
if (!len)
goto out;
/* Check all required entries [svcn, encv1) available. */
if (!run_lookup(run, svcn, &i))
return -ENOENT;
r_end = run->runs + run->count;
r = run->runs + i;
for (next_vcn = r->vcn + r->len; next_vcn < evcn1;
next_vcn = r->vcn + r->len) {
if (++r >= r_end || r->vcn != next_vcn)
return -ENOENT;
}
/* Repeat cycle above and pack runs. Assume no errors. */
r = run->runs + i;
len = svcn - r->vcn;
vcn = svcn;
lcn = r->lcn == SPARSE_LCN ? SPARSE_LCN : (r->lcn + len);
len = r->len - len;
for (;;) {
next_vcn = vcn + len;
if (next_vcn > evcn1)
len = evcn1 - vcn;
/* How much bytes required to pack len. */
size_size = run_packed_size(len);
/* offset_size - How much bytes is packed dlcn. */
if (lcn == SPARSE_LCN) {
offset_size = 0;
dlcn = 0;
} else {
/* NOTE: lcn can be less than prev_lcn! */
dlcn = (s64)lcn - prev_lcn;
offset_size = run_packed_size(dlcn);
prev_lcn = lcn;
}
tmp = run_buf_size - packed_size - 2 - offset_size;
if (tmp <= 0)
goto out;
/* Can we store this entire run. */
if (tmp < size_size)
goto out;
if (run_buf) {
/* Pack run header. */
run_buf[0] = ((u8)(size_size | (offset_size << 4)));
run_buf += 1;
/* Pack the length of run. */
run_pack_s64(run_buf, size_size, len);
run_buf += size_size;
/* Pack the offset from previous LCN. */
run_pack_s64(run_buf, offset_size, dlcn);
run_buf += offset_size;
}
packed_size += 1 + offset_size + size_size;
*packed_vcns += len;
if (packed_size + 1 >= run_buf_size || next_vcn >= evcn1)
goto out;
r += 1;
vcn = r->vcn;
lcn = r->lcn;
len = r->len;
}
out:
/* Store last zero. */
if (run_buf)
run_buf[0] = 0;
return packed_size + 1;
}
/*
* run_unpack - Unpack packed runs from @run_buf.
*
* Return: Error if negative, or real used bytes.
*/
int run_unpack(struct runs_tree *run, struct ntfs_sb_info *sbi, CLST ino,
CLST svcn, CLST evcn, CLST vcn, const u8 *run_buf,
int run_buf_size)
{
u64 prev_lcn, vcn64, lcn, next_vcn;
const u8 *run_last, *run_0;
bool is_mft = ino == MFT_REC_MFT;
if (run_buf_size < 0)
return -EINVAL;
/* Check for empty. */
if (evcn + 1 == svcn)
return 0;
if (evcn < svcn)
return -EINVAL;
run_0 = run_buf;
run_last = run_buf + run_buf_size;
prev_lcn = 0;
vcn64 = svcn;
/* Read all runs the chain. */
/* size_size - How much bytes is packed len. */
while (run_buf < run_last) {
/* size_size - How much bytes is packed len. */
u8 size_size = *run_buf & 0xF;
/* offset_size - How much bytes is packed dlcn. */
u8 offset_size = *run_buf++ >> 4;
u64 len;
if (!size_size)
break;
/*
* Unpack runs.
* NOTE: Runs are stored little endian order
* "len" is unsigned value, "dlcn" is signed.
* Large positive number requires to store 5 bytes
* e.g.: 05 FF 7E FF FF 00 00 00
*/
if (size_size > 8)
return -EINVAL;
len = run_unpack_s64(run_buf, size_size, 0);
/* Skip size_size. */
run_buf += size_size;
if (!len)
return -EINVAL;
if (!offset_size)
lcn = SPARSE_LCN64;
else if (offset_size <= 8) {
s64 dlcn;
/* Initial value of dlcn is -1 or 0. */
dlcn = (run_buf[offset_size - 1] & 0x80) ? (s64)-1 : 0;
dlcn = run_unpack_s64(run_buf, offset_size, dlcn);
/* Skip offset_size. */
run_buf += offset_size;
if (!dlcn)
return -EINVAL;
lcn = prev_lcn + dlcn;
prev_lcn = lcn;
} else
return -EINVAL;
next_vcn = vcn64 + len;
/* Check boundary. */
if (next_vcn > evcn + 1)
return -EINVAL;
#ifndef CONFIG_NTFS3_64BIT_CLUSTER
if (next_vcn > 0x100000000ull || (lcn + len) > 0x100000000ull) {
ntfs_err(
sbi->sb,
"This driver is compiled without CONFIG_NTFS3_64BIT_CLUSTER (like windows driver).\n"
"Volume contains 64 bits run: vcn %llx, lcn %llx, len %llx.\n"