linux/fs/ntfs/runlist.c
Thomas Gleixner a1d312de77 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 96
Based on 1 normalized pattern(s):

  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

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 43 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190520075212.517001706@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-24 17:37:53 +02:00

1894 lines
59 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/**
* runlist.c - NTFS runlist handling code. Part of the Linux-NTFS project.
*
* Copyright (c) 2001-2007 Anton Altaparmakov
* Copyright (c) 2002-2005 Richard Russon
*/
#include "debug.h"
#include "dir.h"
#include "endian.h"
#include "malloc.h"
#include "ntfs.h"
/**
* ntfs_rl_mm - runlist memmove
*
* It is up to the caller to serialize access to the runlist @base.
*/
static inline void ntfs_rl_mm(runlist_element *base, int dst, int src,
int size)
{
if (likely((dst != src) && (size > 0)))
memmove(base + dst, base + src, size * sizeof(*base));
}
/**
* ntfs_rl_mc - runlist memory copy
*
* It is up to the caller to serialize access to the runlists @dstbase and
* @srcbase.
*/
static inline void ntfs_rl_mc(runlist_element *dstbase, int dst,
runlist_element *srcbase, int src, int size)
{
if (likely(size > 0))
memcpy(dstbase + dst, srcbase + src, size * sizeof(*dstbase));
}
/**
* ntfs_rl_realloc - Reallocate memory for runlists
* @rl: original runlist
* @old_size: number of runlist elements in the original runlist @rl
* @new_size: number of runlist elements we need space for
*
* As the runlists grow, more memory will be required. To prevent the
* kernel having to allocate and reallocate large numbers of small bits of
* memory, this function returns an entire page of memory.
*
* It is up to the caller to serialize access to the runlist @rl.
*
* N.B. If the new allocation doesn't require a different number of pages in
* memory, the function will return the original pointer.
*
* On success, return a pointer to the newly allocated, or recycled, memory.
* On error, return -errno. The following error codes are defined:
* -ENOMEM - Not enough memory to allocate runlist array.
* -EINVAL - Invalid parameters were passed in.
*/
static inline runlist_element *ntfs_rl_realloc(runlist_element *rl,
int old_size, int new_size)
{
runlist_element *new_rl;
old_size = PAGE_ALIGN(old_size * sizeof(*rl));
new_size = PAGE_ALIGN(new_size * sizeof(*rl));
if (old_size == new_size)
return rl;
new_rl = ntfs_malloc_nofs(new_size);
if (unlikely(!new_rl))
return ERR_PTR(-ENOMEM);
if (likely(rl != NULL)) {
if (unlikely(old_size > new_size))
old_size = new_size;
memcpy(new_rl, rl, old_size);
ntfs_free(rl);
}
return new_rl;
}
/**
* ntfs_rl_realloc_nofail - Reallocate memory for runlists
* @rl: original runlist
* @old_size: number of runlist elements in the original runlist @rl
* @new_size: number of runlist elements we need space for
*
* As the runlists grow, more memory will be required. To prevent the
* kernel having to allocate and reallocate large numbers of small bits of
* memory, this function returns an entire page of memory.
*
* This function guarantees that the allocation will succeed. It will sleep
* for as long as it takes to complete the allocation.
*
* It is up to the caller to serialize access to the runlist @rl.
*
* N.B. If the new allocation doesn't require a different number of pages in
* memory, the function will return the original pointer.
*
* On success, return a pointer to the newly allocated, or recycled, memory.
* On error, return -errno. The following error codes are defined:
* -ENOMEM - Not enough memory to allocate runlist array.
* -EINVAL - Invalid parameters were passed in.
*/
static inline runlist_element *ntfs_rl_realloc_nofail(runlist_element *rl,
int old_size, int new_size)
{
runlist_element *new_rl;
old_size = PAGE_ALIGN(old_size * sizeof(*rl));
new_size = PAGE_ALIGN(new_size * sizeof(*rl));
if (old_size == new_size)
return rl;
new_rl = ntfs_malloc_nofs_nofail(new_size);
BUG_ON(!new_rl);
if (likely(rl != NULL)) {
if (unlikely(old_size > new_size))
old_size = new_size;
memcpy(new_rl, rl, old_size);
ntfs_free(rl);
}
return new_rl;
}
/**
* ntfs_are_rl_mergeable - test if two runlists can be joined together
* @dst: original runlist
* @src: new runlist to test for mergeability with @dst
*
* Test if two runlists can be joined together. For this, their VCNs and LCNs
* must be adjacent.
*
* It is up to the caller to serialize access to the runlists @dst and @src.
*
* Return: true Success, the runlists can be merged.
* false Failure, the runlists cannot be merged.
*/
static inline bool ntfs_are_rl_mergeable(runlist_element *dst,
runlist_element *src)
{
BUG_ON(!dst);
BUG_ON(!src);
/* We can merge unmapped regions even if they are misaligned. */
if ((dst->lcn == LCN_RL_NOT_MAPPED) && (src->lcn == LCN_RL_NOT_MAPPED))
return true;
/* If the runs are misaligned, we cannot merge them. */
if ((dst->vcn + dst->length) != src->vcn)
return false;
/* If both runs are non-sparse and contiguous, we can merge them. */
if ((dst->lcn >= 0) && (src->lcn >= 0) &&
((dst->lcn + dst->length) == src->lcn))
return true;
/* If we are merging two holes, we can merge them. */
if ((dst->lcn == LCN_HOLE) && (src->lcn == LCN_HOLE))
return true;
/* Cannot merge. */
return false;
}
/**
* __ntfs_rl_merge - merge two runlists without testing if they can be merged
* @dst: original, destination runlist
* @src: new runlist to merge with @dst
*
* Merge the two runlists, writing into the destination runlist @dst. The
* caller must make sure the runlists can be merged or this will corrupt the
* destination runlist.
*
* It is up to the caller to serialize access to the runlists @dst and @src.
*/
static inline void __ntfs_rl_merge(runlist_element *dst, runlist_element *src)
{
dst->length += src->length;
}
/**
* ntfs_rl_append - append a runlist after a given element
* @dst: original runlist to be worked on
* @dsize: number of elements in @dst (including end marker)
* @src: runlist to be inserted into @dst
* @ssize: number of elements in @src (excluding end marker)
* @loc: append the new runlist @src after this element in @dst
*
* Append the runlist @src after element @loc in @dst. Merge the right end of
* the new runlist, if necessary. Adjust the size of the hole before the
* appended runlist.
*
* It is up to the caller to serialize access to the runlists @dst and @src.
*
* On success, return a pointer to the new, combined, runlist. Note, both
* runlists @dst and @src are deallocated before returning so you cannot use
* the pointers for anything any more. (Strictly speaking the returned runlist
* may be the same as @dst but this is irrelevant.)
*
* On error, return -errno. Both runlists are left unmodified. The following
* error codes are defined:
* -ENOMEM - Not enough memory to allocate runlist array.
* -EINVAL - Invalid parameters were passed in.
*/
static inline runlist_element *ntfs_rl_append(runlist_element *dst,
int dsize, runlist_element *src, int ssize, int loc)
{
bool right = false; /* Right end of @src needs merging. */
int marker; /* End of the inserted runs. */
BUG_ON(!dst);
BUG_ON(!src);
/* First, check if the right hand end needs merging. */
if ((loc + 1) < dsize)
right = ntfs_are_rl_mergeable(src + ssize - 1, dst + loc + 1);
/* Space required: @dst size + @src size, less one if we merged. */
dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - right);
if (IS_ERR(dst))
return dst;
/*
* We are guaranteed to succeed from here so can start modifying the
* original runlists.
*/
/* First, merge the right hand end, if necessary. */
if (right)
__ntfs_rl_merge(src + ssize - 1, dst + loc + 1);
/* First run after the @src runs that have been inserted. */
marker = loc + ssize + 1;
/* Move the tail of @dst out of the way, then copy in @src. */
ntfs_rl_mm(dst, marker, loc + 1 + right, dsize - (loc + 1 + right));
ntfs_rl_mc(dst, loc + 1, src, 0, ssize);
/* Adjust the size of the preceding hole. */
dst[loc].length = dst[loc + 1].vcn - dst[loc].vcn;
/* We may have changed the length of the file, so fix the end marker */
if (dst[marker].lcn == LCN_ENOENT)
dst[marker].vcn = dst[marker - 1].vcn + dst[marker - 1].length;
return dst;
}
/**
* ntfs_rl_insert - insert a runlist into another
* @dst: original runlist to be worked on
* @dsize: number of elements in @dst (including end marker)
* @src: new runlist to be inserted
* @ssize: number of elements in @src (excluding end marker)
* @loc: insert the new runlist @src before this element in @dst
*
* Insert the runlist @src before element @loc in the runlist @dst. Merge the
* left end of the new runlist, if necessary. Adjust the size of the hole
* after the inserted runlist.
*
* It is up to the caller to serialize access to the runlists @dst and @src.
*
* On success, return a pointer to the new, combined, runlist. Note, both
* runlists @dst and @src are deallocated before returning so you cannot use
* the pointers for anything any more. (Strictly speaking the returned runlist
* may be the same as @dst but this is irrelevant.)
*
* On error, return -errno. Both runlists are left unmodified. The following
* error codes are defined:
* -ENOMEM - Not enough memory to allocate runlist array.
* -EINVAL - Invalid parameters were passed in.
*/
static inline runlist_element *ntfs_rl_insert(runlist_element *dst,
int dsize, runlist_element *src, int ssize, int loc)
{
bool left = false; /* Left end of @src needs merging. */
bool disc = false; /* Discontinuity between @dst and @src. */
int marker; /* End of the inserted runs. */
BUG_ON(!dst);
BUG_ON(!src);
/*
* disc => Discontinuity between the end of @dst and the start of @src.
* This means we might need to insert a "not mapped" run.
*/
if (loc == 0)
disc = (src[0].vcn > 0);
else {
s64 merged_length;
left = ntfs_are_rl_mergeable(dst + loc - 1, src);
merged_length = dst[loc - 1].length;
if (left)
merged_length += src->length;
disc = (src[0].vcn > dst[loc - 1].vcn + merged_length);
}
/*
* Space required: @dst size + @src size, less one if we merged, plus
* one if there was a discontinuity.
*/
dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - left + disc);
if (IS_ERR(dst))
return dst;
/*
* We are guaranteed to succeed from here so can start modifying the
* original runlist.
*/
if (left)
__ntfs_rl_merge(dst + loc - 1, src);
/*
* First run after the @src runs that have been inserted.
* Nominally, @marker equals @loc + @ssize, i.e. location + number of
* runs in @src. However, if @left, then the first run in @src has
* been merged with one in @dst. And if @disc, then @dst and @src do
* not meet and we need an extra run to fill the gap.
*/
marker = loc + ssize - left + disc;
/* Move the tail of @dst out of the way, then copy in @src. */
ntfs_rl_mm(dst, marker, loc, dsize - loc);
ntfs_rl_mc(dst, loc + disc, src, left, ssize - left);
/* Adjust the VCN of the first run after the insertion... */
dst[marker].vcn = dst[marker - 1].vcn + dst[marker - 1].length;
/* ... and the length. */
if (dst[marker].lcn == LCN_HOLE || dst[marker].lcn == LCN_RL_NOT_MAPPED)
dst[marker].length = dst[marker + 1].vcn - dst[marker].vcn;
/* Writing beyond the end of the file and there is a discontinuity. */
if (disc) {
if (loc > 0) {
dst[loc].vcn = dst[loc - 1].vcn + dst[loc - 1].length;
dst[loc].length = dst[loc + 1].vcn - dst[loc].vcn;
} else {
dst[loc].vcn = 0;
dst[loc].length = dst[loc + 1].vcn;
}
dst[loc].lcn = LCN_RL_NOT_MAPPED;
}
return dst;
}
/**
* ntfs_rl_replace - overwrite a runlist element with another runlist
* @dst: original runlist to be worked on
* @dsize: number of elements in @dst (including end marker)
* @src: new runlist to be inserted
* @ssize: number of elements in @src (excluding end marker)
* @loc: index in runlist @dst to overwrite with @src
*
* Replace the runlist element @dst at @loc with @src. Merge the left and
* right ends of the inserted runlist, if necessary.
*
* It is up to the caller to serialize access to the runlists @dst and @src.
*
* On success, return a pointer to the new, combined, runlist. Note, both
* runlists @dst and @src are deallocated before returning so you cannot use
* the pointers for anything any more. (Strictly speaking the returned runlist
* may be the same as @dst but this is irrelevant.)
*
* On error, return -errno. Both runlists are left unmodified. The following
* error codes are defined:
* -ENOMEM - Not enough memory to allocate runlist array.
* -EINVAL - Invalid parameters were passed in.
*/
static inline runlist_element *ntfs_rl_replace(runlist_element *dst,
int dsize, runlist_element *src, int ssize, int loc)
{
signed delta;
bool left = false; /* Left end of @src needs merging. */
bool right = false; /* Right end of @src needs merging. */
int tail; /* Start of tail of @dst. */
int marker; /* End of the inserted runs. */
BUG_ON(!dst);
BUG_ON(!src);
/* First, see if the left and right ends need merging. */
if ((loc + 1) < dsize)
right = ntfs_are_rl_mergeable(src + ssize - 1, dst + loc + 1);
if (loc > 0)
left = ntfs_are_rl_mergeable(dst + loc - 1, src);
/*
* Allocate some space. We will need less if the left, right, or both
* ends get merged. The -1 accounts for the run being replaced.
*/
delta = ssize - 1 - left - right;
if (delta > 0) {
dst = ntfs_rl_realloc(dst, dsize, dsize + delta);
if (IS_ERR(dst))
return dst;
}
/*
* We are guaranteed to succeed from here so can start modifying the
* original runlists.
*/
/* First, merge the left and right ends, if necessary. */
if (right)
__ntfs_rl_merge(src + ssize - 1, dst + loc + 1);
if (left)
__ntfs_rl_merge(dst + loc - 1, src);
/*
* Offset of the tail of @dst. This needs to be moved out of the way
* to make space for the runs to be copied from @src, i.e. the first
* run of the tail of @dst.
* Nominally, @tail equals @loc + 1, i.e. location, skipping the
* replaced run. However, if @right, then one of @dst's runs is
* already merged into @src.
*/
tail = loc + right + 1;
/*
* First run after the @src runs that have been inserted, i.e. where
* the tail of @dst needs to be moved to.
* Nominally, @marker equals @loc + @ssize, i.e. location + number of
* runs in @src. However, if @left, then the first run in @src has
* been merged with one in @dst.
*/
marker = loc + ssize - left;
/* Move the tail of @dst out of the way, then copy in @src. */
ntfs_rl_mm(dst, marker, tail, dsize - tail);
ntfs_rl_mc(dst, loc, src, left, ssize - left);
/* We may have changed the length of the file, so fix the end marker. */
if (dsize - tail > 0 && dst[marker].lcn == LCN_ENOENT)
dst[marker].vcn = dst[marker - 1].vcn + dst[marker - 1].length;
return dst;
}
/**
* ntfs_rl_split - insert a runlist into the centre of a hole
* @dst: original runlist to be worked on
* @dsize: number of elements in @dst (including end marker)
* @src: new runlist to be inserted
* @ssize: number of elements in @src (excluding end marker)
* @loc: index in runlist @dst at which to split and insert @src
*
* Split the runlist @dst at @loc into two and insert @new in between the two
* fragments. No merging of runlists is necessary. Adjust the size of the
* holes either side.
*
* It is up to the caller to serialize access to the runlists @dst and @src.
*
* On success, return a pointer to the new, combined, runlist. Note, both
* runlists @dst and @src are deallocated before returning so you cannot use
* the pointers for anything any more. (Strictly speaking the returned runlist
* may be the same as @dst but this is irrelevant.)
*
* On error, return -errno. Both runlists are left unmodified. The following
* error codes are defined:
* -ENOMEM - Not enough memory to allocate runlist array.
* -EINVAL - Invalid parameters were passed in.
*/
static inline runlist_element *ntfs_rl_split(runlist_element *dst, int dsize,
runlist_element *src, int ssize, int loc)
{
BUG_ON(!dst);
BUG_ON(!src);
/* Space required: @dst size + @src size + one new hole. */
dst = ntfs_rl_realloc(dst, dsize, dsize + ssize + 1);
if (IS_ERR(dst))
return dst;
/*
* We are guaranteed to succeed from here so can start modifying the
* original runlists.
*/
/* Move the tail of @dst out of the way, then copy in @src. */
ntfs_rl_mm(dst, loc + 1 + ssize, loc, dsize - loc);
ntfs_rl_mc(dst, loc + 1, src, 0, ssize);
/* Adjust the size of the holes either size of @src. */
dst[loc].length = dst[loc+1].vcn - dst[loc].vcn;
dst[loc+ssize+1].vcn = dst[loc+ssize].vcn + dst[loc+ssize].length;
dst[loc+ssize+1].length = dst[loc+ssize+2].vcn - dst[loc+ssize+1].vcn;
return dst;
}
/**
* ntfs_runlists_merge - merge two runlists into one
* @drl: original runlist to be worked on
* @srl: new runlist to be merged into @drl
*
* First we sanity check the two runlists @srl and @drl to make sure that they
* are sensible and can be merged. The runlist @srl must be either after the
* runlist @drl or completely within a hole (or unmapped region) in @drl.
*
* It is up to the caller to serialize access to the runlists @drl and @srl.
*
* Merging of runlists is necessary in two cases:
* 1. When attribute lists are used and a further extent is being mapped.
* 2. When new clusters are allocated to fill a hole or extend a file.
*
* There are four possible ways @srl can be merged. It can:
* - be inserted at the beginning of a hole,
* - split the hole in two and be inserted between the two fragments,
* - be appended at the end of a hole, or it can
* - replace the whole hole.
* It can also be appended to the end of the runlist, which is just a variant
* of the insert case.
*
* On success, return a pointer to the new, combined, runlist. Note, both
* runlists @drl and @srl are deallocated before returning so you cannot use
* the pointers for anything any more. (Strictly speaking the returned runlist
* may be the same as @dst but this is irrelevant.)
*
* On error, return -errno. Both runlists are left unmodified. The following
* error codes are defined:
* -ENOMEM - Not enough memory to allocate runlist array.
* -EINVAL - Invalid parameters were passed in.
* -ERANGE - The runlists overlap and cannot be merged.
*/
runlist_element *ntfs_runlists_merge(runlist_element *drl,
runlist_element *srl)
{
int di, si; /* Current index into @[ds]rl. */
int sstart; /* First index with lcn > LCN_RL_NOT_MAPPED. */
int dins; /* Index into @drl at which to insert @srl. */
int dend, send; /* Last index into @[ds]rl. */
int dfinal, sfinal; /* The last index into @[ds]rl with
lcn >= LCN_HOLE. */
int marker = 0;
VCN marker_vcn = 0;
#ifdef DEBUG
ntfs_debug("dst:");
ntfs_debug_dump_runlist(drl);
ntfs_debug("src:");
ntfs_debug_dump_runlist(srl);
#endif
/* Check for silly calling... */
if (unlikely(!srl))
return drl;
if (IS_ERR(srl) || IS_ERR(drl))
return ERR_PTR(-EINVAL);
/* Check for the case where the first mapping is being done now. */
if (unlikely(!drl)) {
drl = srl;
/* Complete the source runlist if necessary. */
if (unlikely(drl[0].vcn)) {
/* Scan to the end of the source runlist. */
for (dend = 0; likely(drl[dend].length); dend++)
;
dend++;
drl = ntfs_rl_realloc(drl, dend, dend + 1);
if (IS_ERR(drl))
return drl;
/* Insert start element at the front of the runlist. */
ntfs_rl_mm(drl, 1, 0, dend);
drl[0].vcn = 0;
drl[0].lcn = LCN_RL_NOT_MAPPED;
drl[0].length = drl[1].vcn;
}
goto finished;
}
si = di = 0;
/* Skip any unmapped start element(s) in the source runlist. */
while (srl[si].length && srl[si].lcn < LCN_HOLE)
si++;
/* Can't have an entirely unmapped source runlist. */
BUG_ON(!srl[si].length);
/* Record the starting points. */
sstart = si;
/*
* Skip forward in @drl until we reach the position where @srl needs to
* be inserted. If we reach the end of @drl, @srl just needs to be
* appended to @drl.
*/
for (; drl[di].length; di++) {
if (drl[di].vcn + drl[di].length > srl[sstart].vcn)
break;
}
dins = di;
/* Sanity check for illegal overlaps. */
if ((drl[di].vcn == srl[si].vcn) && (drl[di].lcn >= 0) &&
(srl[si].lcn >= 0)) {
ntfs_error(NULL, "Run lists overlap. Cannot merge!");
return ERR_PTR(-ERANGE);
}
/* Scan to the end of both runlists in order to know their sizes. */
for (send = si; srl[send].length; send++)
;
for (dend = di; drl[dend].length; dend++)
;
if (srl[send].lcn == LCN_ENOENT)
marker_vcn = srl[marker = send].vcn;
/* Scan to the last element with lcn >= LCN_HOLE. */
for (sfinal = send; sfinal >= 0 && srl[sfinal].lcn < LCN_HOLE; sfinal--)
;
for (dfinal = dend; dfinal >= 0 && drl[dfinal].lcn < LCN_HOLE; dfinal--)
;
{
bool start;
bool finish;
int ds = dend + 1; /* Number of elements in drl & srl */
int ss = sfinal - sstart + 1;
start = ((drl[dins].lcn < LCN_RL_NOT_MAPPED) || /* End of file */
(drl[dins].vcn == srl[sstart].vcn)); /* Start of hole */
finish = ((drl[dins].lcn >= LCN_RL_NOT_MAPPED) && /* End of file */
((drl[dins].vcn + drl[dins].length) <= /* End of hole */
(srl[send - 1].vcn + srl[send - 1].length)));
/* Or we will lose an end marker. */
if (finish && !drl[dins].length)
ss++;
if (marker && (drl[dins].vcn + drl[dins].length > srl[send - 1].vcn))
finish = false;
#if 0
ntfs_debug("dfinal = %i, dend = %i", dfinal, dend);
ntfs_debug("sstart = %i, sfinal = %i, send = %i", sstart, sfinal, send);
ntfs_debug("start = %i, finish = %i", start, finish);
ntfs_debug("ds = %i, ss = %i, dins = %i", ds, ss, dins);
#endif
if (start) {
if (finish)
drl = ntfs_rl_replace(drl, ds, srl + sstart, ss, dins);
else
drl = ntfs_rl_insert(drl, ds, srl + sstart, ss, dins);
} else {
if (finish)
drl = ntfs_rl_append(drl, ds, srl + sstart, ss, dins);
else
drl = ntfs_rl_split(drl, ds, srl + sstart, ss, dins);
}
if (IS_ERR(drl)) {
ntfs_error(NULL, "Merge failed.");
return drl;
}
ntfs_free(srl);
if (marker) {
ntfs_debug("Triggering marker code.");
for (ds = dend; drl[ds].length; ds++)
;
/* We only need to care if @srl ended after @drl. */
if (drl[ds].vcn <= marker_vcn) {
int slots = 0;
if (drl[ds].vcn == marker_vcn) {
ntfs_debug("Old marker = 0x%llx, replacing "
"with LCN_ENOENT.",
(unsigned long long)
drl[ds].lcn);
drl[ds].lcn = LCN_ENOENT;
goto finished;
}
/*
* We need to create an unmapped runlist element in
* @drl or extend an existing one before adding the
* ENOENT terminator.
*/
if (drl[ds].lcn == LCN_ENOENT) {
ds--;
slots = 1;
}
if (drl[ds].lcn != LCN_RL_NOT_MAPPED) {
/* Add an unmapped runlist element. */
if (!slots) {
drl = ntfs_rl_realloc_nofail(drl, ds,
ds + 2);
slots = 2;
}
ds++;
/* Need to set vcn if it isn't set already. */
if (slots != 1)
drl[ds].vcn = drl[ds - 1].vcn +
drl[ds - 1].length;
drl[ds].lcn = LCN_RL_NOT_MAPPED;
/* We now used up a slot. */
slots--;
}
drl[ds].length = marker_vcn - drl[ds].vcn;
/* Finally add the ENOENT terminator. */
ds++;
if (!slots)
drl = ntfs_rl_realloc_nofail(drl, ds, ds + 1);
drl[ds].vcn = marker_vcn;
drl[ds].lcn = LCN_ENOENT;
drl[ds].length = (s64)0;
}
}
}
finished:
/* The merge was completed successfully. */
ntfs_debug("Merged runlist:");
ntfs_debug_dump_runlist(drl);
return drl;
}
/**
* ntfs_mapping_pairs_decompress - convert mapping pairs array to runlist
* @vol: ntfs volume on which the attribute resides
* @attr: attribute record whose mapping pairs array to decompress
* @old_rl: optional runlist in which to insert @attr's runlist
*
* It is up to the caller to serialize access to the runlist @old_rl.
*
* Decompress the attribute @attr's mapping pairs array into a runlist. On
* success, return the decompressed runlist.
*
* If @old_rl is not NULL, decompressed runlist is inserted into the
* appropriate place in @old_rl and the resultant, combined runlist is
* returned. The original @old_rl is deallocated.
*
* On error, return -errno. @old_rl is left unmodified in that case.
*
* The following error codes are defined:
* -ENOMEM - Not enough memory to allocate runlist array.
* -EIO - Corrupt runlist.
* -EINVAL - Invalid parameters were passed in.
* -ERANGE - The two runlists overlap.
*
* FIXME: For now we take the conceptionally simplest approach of creating the
* new runlist disregarding the already existing one and then splicing the
* two into one, if that is possible (we check for overlap and discard the new
* runlist if overlap present before returning ERR_PTR(-ERANGE)).
*/
runlist_element *ntfs_mapping_pairs_decompress(const ntfs_volume *vol,
const ATTR_RECORD *attr, runlist_element *old_rl)
{
VCN vcn; /* Current vcn. */
LCN lcn; /* Current lcn. */
s64 deltaxcn; /* Change in [vl]cn. */
runlist_element *rl; /* The output runlist. */
u8 *buf; /* Current position in mapping pairs array. */
u8 *attr_end; /* End of attribute. */
int rlsize; /* Size of runlist buffer. */
u16 rlpos; /* Current runlist position in units of
runlist_elements. */
u8 b; /* Current byte offset in buf. */
#ifdef DEBUG
/* Make sure attr exists and is non-resident. */
if (!attr || !attr->non_resident || sle64_to_cpu(
attr->data.non_resident.lowest_vcn) < (VCN)0) {
ntfs_error(vol->sb, "Invalid arguments.");
return ERR_PTR(-EINVAL);
}
#endif
/* Start at vcn = lowest_vcn and lcn 0. */
vcn = sle64_to_cpu(attr->data.non_resident.lowest_vcn);
lcn = 0;
/* Get start of the mapping pairs array. */
buf = (u8*)attr + le16_to_cpu(
attr->data.non_resident.mapping_pairs_offset);
attr_end = (u8*)attr + le32_to_cpu(attr->length);
if (unlikely(buf < (u8*)attr || buf > attr_end)) {
ntfs_error(vol->sb, "Corrupt attribute.");
return ERR_PTR(-EIO);
}
/* If the mapping pairs array is valid but empty, nothing to do. */
if (!vcn && !*buf)
return old_rl;
/* Current position in runlist array. */
rlpos = 0;
/* Allocate first page and set current runlist size to one page. */
rl = ntfs_malloc_nofs(rlsize = PAGE_SIZE);
if (unlikely(!rl))
return ERR_PTR(-ENOMEM);
/* Insert unmapped starting element if necessary. */
if (vcn) {
rl->vcn = 0;
rl->lcn = LCN_RL_NOT_MAPPED;
rl->length = vcn;
rlpos++;
}
while (buf < attr_end && *buf) {
/*
* Allocate more memory if needed, including space for the
* not-mapped and terminator elements. ntfs_malloc_nofs()
* operates on whole pages only.
*/
if (((rlpos + 3) * sizeof(*old_rl)) > rlsize) {
runlist_element *rl2;
rl2 = ntfs_malloc_nofs(rlsize + (int)PAGE_SIZE);
if (unlikely(!rl2)) {
ntfs_free(rl);
return ERR_PTR(-ENOMEM);
}
memcpy(rl2, rl, rlsize);
ntfs_free(rl);
rl = rl2;
rlsize += PAGE_SIZE;
}
/* Enter the current vcn into the current runlist element. */
rl[rlpos].vcn = vcn;
/*
* Get the change in vcn, i.e. the run length in clusters.
* Doing it this way ensures that we signextend negative values.
* A negative run length doesn't make any sense, but hey, I
* didn't make up the NTFS specs and Windows NT4 treats the run
* length as a signed value so that's how it is...
*/
b = *buf & 0xf;
if (b) {
if (unlikely(buf + b > attr_end))
goto io_error;
for (deltaxcn = (s8)buf[b--]; b; b--)
deltaxcn = (deltaxcn << 8) + buf[b];
} else { /* The length entry is compulsory. */
ntfs_error(vol->sb, "Missing length entry in mapping "
"pairs array.");
deltaxcn = (s64)-1;
}
/*
* Assume a negative length to indicate data corruption and
* hence clean-up and return NULL.
*/
if (unlikely(deltaxcn < 0)) {
ntfs_error(vol->sb, "Invalid length in mapping pairs "
"array.");
goto err_out;
}
/*
* Enter the current run length into the current runlist
* element.
*/
rl[rlpos].length = deltaxcn;
/* Increment the current vcn by the current run length. */
vcn += deltaxcn;
/*
* There might be no lcn change at all, as is the case for
* sparse clusters on NTFS 3.0+, in which case we set the lcn
* to LCN_HOLE.
*/
if (!(*buf & 0xf0))
rl[rlpos].lcn = LCN_HOLE;
else {
/* Get the lcn change which really can be negative. */
u8 b2 = *buf & 0xf;
b = b2 + ((*buf >> 4) & 0xf);
if (buf + b > attr_end)
goto io_error;
for (deltaxcn = (s8)buf[b--]; b > b2; b--)
deltaxcn = (deltaxcn << 8) + buf[b];
/* Change the current lcn to its new value. */
lcn += deltaxcn;
#ifdef DEBUG
/*
* On NTFS 1.2-, apparently can have lcn == -1 to
* indicate a hole. But we haven't verified ourselves
* whether it is really the lcn or the deltaxcn that is
* -1. So if either is found give us a message so we
* can investigate it further!
*/
if (vol->major_ver < 3) {
if (unlikely(deltaxcn == (LCN)-1))
ntfs_error(vol->sb, "lcn delta == -1");
if (unlikely(lcn == (LCN)-1))
ntfs_error(vol->sb, "lcn == -1");
}
#endif
/* Check lcn is not below -1. */
if (unlikely(lcn < (LCN)-1)) {
ntfs_error(vol->sb, "Invalid LCN < -1 in "
"mapping pairs array.");
goto err_out;
}
/* Enter the current lcn into the runlist element. */
rl[rlpos].lcn = lcn;
}
/* Get to the next runlist element. */
rlpos++;
/* Increment the buffer position to the next mapping pair. */
buf += (*buf & 0xf) + ((*buf >> 4) & 0xf) + 1;
}
if (unlikely(buf >= attr_end))
goto io_error;
/*
* If there is a highest_vcn specified, it must be equal to the final
* vcn in the runlist - 1, or something has gone badly wrong.
*/
deltaxcn = sle64_to_cpu(attr->data.non_resident.highest_vcn);
if (unlikely(deltaxcn && vcn - 1 != deltaxcn)) {
mpa_err:
ntfs_error(vol->sb, "Corrupt mapping pairs array in "
"non-resident attribute.");
goto err_out;
}
/* Setup not mapped runlist element if this is the base extent. */
if (!attr->data.non_resident.lowest_vcn) {
VCN max_cluster;
max_cluster = ((sle64_to_cpu(
attr->data.non_resident.allocated_size) +
vol->cluster_size - 1) >>
vol->cluster_size_bits) - 1;
/*
* A highest_vcn of zero means this is a single extent
* attribute so simply terminate the runlist with LCN_ENOENT).
*/
if (deltaxcn) {
/*
* If there is a difference between the highest_vcn and
* the highest cluster, the runlist is either corrupt
* or, more likely, there are more extents following
* this one.
*/
if (deltaxcn < max_cluster) {
ntfs_debug("More extents to follow; deltaxcn "
"= 0x%llx, max_cluster = "
"0x%llx",
(unsigned long long)deltaxcn,
(unsigned long long)
max_cluster);
rl[rlpos].vcn = vcn;
vcn += rl[rlpos].length = max_cluster -
deltaxcn;
rl[rlpos].lcn = LCN_RL_NOT_MAPPED;
rlpos++;
} else if (unlikely(deltaxcn > max_cluster)) {
ntfs_error(vol->sb, "Corrupt attribute. "
"deltaxcn = 0x%llx, "
"max_cluster = 0x%llx",
(unsigned long long)deltaxcn,
(unsigned long long)
max_cluster);
goto mpa_err;
}
}
rl[rlpos].lcn = LCN_ENOENT;
} else /* Not the base extent. There may be more extents to follow. */
rl[rlpos].lcn = LCN_RL_NOT_MAPPED;
/* Setup terminating runlist element. */
rl[rlpos].vcn = vcn;
rl[rlpos].length = (s64)0;
/* If no existing runlist was specified, we are done. */
if (!old_rl) {
ntfs_debug("Mapping pairs array successfully decompressed:");
ntfs_debug_dump_runlist(rl);
return rl;
}
/* Now combine the new and old runlists checking for overlaps. */
old_rl = ntfs_runlists_merge(old_rl, rl);
if (likely(!IS_ERR(old_rl)))
return old_rl;
ntfs_free(rl);
ntfs_error(vol->sb, "Failed to merge runlists.");
return old_rl;
io_error:
ntfs_error(vol->sb, "Corrupt attribute.");
err_out:
ntfs_free(rl);
return ERR_PTR(-EIO);
}
/**
* ntfs_rl_vcn_to_lcn - convert a vcn into a lcn given a runlist
* @rl: runlist to use for conversion
* @vcn: vcn to convert
*
* Convert the virtual cluster number @vcn of an attribute into a logical
* cluster number (lcn) of a device using the runlist @rl to map vcns to their
* corresponding lcns.
*
* It is up to the caller to serialize access to the runlist @rl.
*
* Since lcns must be >= 0, we use negative return codes with special meaning:
*
* Return code Meaning / Description
* ==================================================
* LCN_HOLE Hole / not allocated on disk.
* LCN_RL_NOT_MAPPED This is part of the runlist which has not been
* inserted into the runlist yet.
* LCN_ENOENT There is no such vcn in the attribute.
*
* Locking: - The caller must have locked the runlist (for reading or writing).
* - This function does not touch the lock, nor does it modify the
* runlist.
*/
LCN ntfs_rl_vcn_to_lcn(const runlist_element *rl, const VCN vcn)
{
int i;
BUG_ON(vcn < 0);
/*
* If rl is NULL, assume that we have found an unmapped runlist. The
* caller can then attempt to map it and fail appropriately if
* necessary.
*/
if (unlikely(!rl))
return LCN_RL_NOT_MAPPED;
/* Catch out of lower bounds vcn. */
if (unlikely(vcn < rl[0].vcn))
return LCN_ENOENT;
for (i = 0; likely(rl[i].length); i++) {
if (unlikely(vcn < rl[i+1].vcn)) {
if (likely(rl[i].lcn >= (LCN)0))
return rl[i].lcn + (vcn - rl[i].vcn);
return rl[i].lcn;
}
}
/*
* The terminator element is setup to the correct value, i.e. one of
* LCN_HOLE, LCN_RL_NOT_MAPPED, or LCN_ENOENT.
*/
if (likely(rl[i].lcn < (LCN)0))
return rl[i].lcn;
/* Just in case... We could replace this with BUG() some day. */
return LCN_ENOENT;
}
#ifdef NTFS_RW
/**
* ntfs_rl_find_vcn_nolock - find a vcn in a runlist
* @rl: runlist to search
* @vcn: vcn to find
*
* Find the virtual cluster number @vcn in the runlist @rl and return the
* address of the runlist element containing the @vcn on success.
*
* Return NULL if @rl is NULL or @vcn is in an unmapped part/out of bounds of
* the runlist.
*
* Locking: The runlist must be locked on entry.
*/
runlist_element *ntfs_rl_find_vcn_nolock(runlist_element *rl, const VCN vcn)
{
BUG_ON(vcn < 0);
if (unlikely(!rl || vcn < rl[0].vcn))
return NULL;
while (likely(rl->length)) {
if (unlikely(vcn < rl[1].vcn)) {
if (likely(rl->lcn >= LCN_HOLE))
return rl;
return NULL;
}
rl++;
}
if (likely(rl->lcn == LCN_ENOENT))
return rl;
return NULL;
}
/**
* ntfs_get_nr_significant_bytes - get number of bytes needed to store a number
* @n: number for which to get the number of bytes for
*
* Return the number of bytes required to store @n unambiguously as
* a signed number.
*
* This is used in the context of the mapping pairs array to determine how
* many bytes will be needed in the array to store a given logical cluster
* number (lcn) or a specific run length.
*
* Return the number of bytes written. This function cannot fail.
*/
static inline int ntfs_get_nr_significant_bytes(const s64 n)
{
s64 l = n;
int i;
s8 j;
i = 0;
do {
l >>= 8;
i++;
} while (l != 0 && l != -1);
j = (n >> 8 * (i - 1)) & 0xff;
/* If the sign bit is wrong, we need an extra byte. */
if ((n < 0 && j >= 0) || (n > 0 && j < 0))
i++;
return i;
}
/**
* ntfs_get_size_for_mapping_pairs - get bytes needed for mapping pairs array
* @vol: ntfs volume (needed for the ntfs version)
* @rl: locked runlist to determine the size of the mapping pairs of
* @first_vcn: first vcn which to include in the mapping pairs array
* @last_vcn: last vcn which to include in the mapping pairs array
*
* Walk the locked runlist @rl and calculate the size in bytes of the mapping
* pairs array corresponding to the runlist @rl, starting at vcn @first_vcn and
* finishing with vcn @last_vcn.
*
* A @last_vcn of -1 means end of runlist and in that case the size of the
* mapping pairs array corresponding to the runlist starting at vcn @first_vcn
* and finishing at the end of the runlist is determined.
*
* This for example allows us to allocate a buffer of the right size when
* building the mapping pairs array.
*
* If @rl is NULL, just return 1 (for the single terminator byte).
*
* Return the calculated size in bytes on success. On error, return -errno.
* The following error codes are defined:
* -EINVAL - Run list contains unmapped elements. Make sure to only pass
* fully mapped runlists to this function.
* -EIO - The runlist is corrupt.
*
* Locking: @rl must be locked on entry (either for reading or writing), it
* remains locked throughout, and is left locked upon return.
*/
int ntfs_get_size_for_mapping_pairs(const ntfs_volume *vol,
const runlist_element *rl, const VCN first_vcn,
const VCN last_vcn)
{
LCN prev_lcn;
int rls;
bool the_end = false;
BUG_ON(first_vcn < 0);
BUG_ON(last_vcn < -1);
BUG_ON(last_vcn >= 0 && first_vcn > last_vcn);
if (!rl) {
BUG_ON(first_vcn);
BUG_ON(last_vcn > 0);
return 1;
}
/* Skip to runlist element containing @first_vcn. */
while (rl->length && first_vcn >= rl[1].vcn)
rl++;
if (unlikely((!rl->length && first_vcn > rl->vcn) ||
first_vcn < rl->vcn))
return -EINVAL;
prev_lcn = 0;
/* Always need the termining zero byte. */
rls = 1;
/* Do the first partial run if present. */
if (first_vcn > rl->vcn) {
s64 delta, length = rl->length;
/* We know rl->length != 0 already. */
if (unlikely(length < 0 || rl->lcn < LCN_HOLE))
goto err_out;
/*
* If @stop_vcn is given and finishes inside this run, cap the
* run length.
*/
if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) {
s64 s1 = last_vcn + 1;
if (unlikely(rl[1].vcn > s1))
length = s1 - rl->vcn;
the_end = true;
}
delta = first_vcn - rl->vcn;
/* Header byte + length. */
rls += 1 + ntfs_get_nr_significant_bytes(length - delta);
/*
* If the logical cluster number (lcn) denotes a hole and we
* are on NTFS 3.0+, we don't store it at all, i.e. we need
* zero space. On earlier NTFS versions we just store the lcn.
* Note: this assumes that on NTFS 1.2-, holes are stored with
* an lcn of -1 and not a delta_lcn of -1 (unless both are -1).
*/
if (likely(rl->lcn >= 0 || vol->major_ver < 3)) {
prev_lcn = rl->lcn;
if (likely(rl->lcn >= 0))
prev_lcn += delta;
/* Change in lcn. */
rls += ntfs_get_nr_significant_bytes(prev_lcn);
}
/* Go to next runlist element. */
rl++;
}
/* Do the full runs. */
for (; rl->length && !the_end; rl++) {
s64 length = rl->length;
if (unlikely(length < 0 || rl->lcn < LCN_HOLE))
goto err_out;
/*
* If @stop_vcn is given and finishes inside this run, cap the
* run length.
*/
if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) {
s64 s1 = last_vcn + 1;
if (unlikely(rl[1].vcn > s1))
length = s1 - rl->vcn;
the_end = true;
}
/* Header byte + length. */
rls += 1 + ntfs_get_nr_significant_bytes(length);
/*
* If the logical cluster number (lcn) denotes a hole and we
* are on NTFS 3.0+, we don't store it at all, i.e. we need
* zero space. On earlier NTFS versions we just store the lcn.
* Note: this assumes that on NTFS 1.2-, holes are stored with
* an lcn of -1 and not a delta_lcn of -1 (unless both are -1).
*/
if (likely(rl->lcn >= 0 || vol->major_ver < 3)) {
/* Change in lcn. */
rls += ntfs_get_nr_significant_bytes(rl->lcn -
prev_lcn);
prev_lcn = rl->lcn;
}
}
return rls;
err_out:
if (rl->lcn == LCN_RL_NOT_MAPPED)
rls = -EINVAL;
else
rls = -EIO;
return rls;
}
/**
* ntfs_write_significant_bytes - write the significant bytes of a number
* @dst: destination buffer to write to
* @dst_max: pointer to last byte of destination buffer for bounds checking
* @n: number whose significant bytes to write
*
* Store in @dst, the minimum bytes of the number @n which are required to
* identify @n unambiguously as a signed number, taking care not to exceed
* @dest_max, the maximum position within @dst to which we are allowed to
* write.
*
* This is used when building the mapping pairs array of a runlist to compress
* a given logical cluster number (lcn) or a specific run length to the minimum
* size possible.
*
* Return the number of bytes written on success. On error, i.e. the
* destination buffer @dst is too small, return -ENOSPC.
*/
static inline int ntfs_write_significant_bytes(s8 *dst, const s8 *dst_max,
const s64 n)
{
s64 l = n;
int i;
s8 j;
i = 0;
do {
if (unlikely(dst > dst_max))
goto err_out;
*dst++ = l & 0xffll;
l >>= 8;
i++;
} while (l != 0 && l != -1);
j = (n >> 8 * (i - 1)) & 0xff;
/* If the sign bit is wrong, we need an extra byte. */
if (n < 0 && j >= 0) {
if (unlikely(dst > dst_max))
goto err_out;
i++;
*dst = (s8)-1;
} else if (n > 0 && j < 0) {
if (unlikely(dst > dst_max))
goto err_out;
i++;
*dst = (s8)0;
}
return i;
err_out:
return -ENOSPC;
}
/**
* ntfs_mapping_pairs_build - build the mapping pairs array from a runlist
* @vol: ntfs volume (needed for the ntfs version)
* @dst: destination buffer to which to write the mapping pairs array
* @dst_len: size of destination buffer @dst in bytes
* @rl: locked runlist for which to build the mapping pairs array
* @first_vcn: first vcn which to include in the mapping pairs array
* @last_vcn: last vcn which to include in the mapping pairs array
* @stop_vcn: first vcn outside destination buffer on success or -ENOSPC
*
* Create the mapping pairs array from the locked runlist @rl, starting at vcn
* @first_vcn and finishing with vcn @last_vcn and save the array in @dst.
* @dst_len is the size of @dst in bytes and it should be at least equal to the
* value obtained by calling ntfs_get_size_for_mapping_pairs().
*
* A @last_vcn of -1 means end of runlist and in that case the mapping pairs
* array corresponding to the runlist starting at vcn @first_vcn and finishing
* at the end of the runlist is created.
*
* If @rl is NULL, just write a single terminator byte to @dst.
*
* On success or -ENOSPC error, if @stop_vcn is not NULL, *@stop_vcn is set to
* the first vcn outside the destination buffer. Note that on error, @dst has
* been filled with all the mapping pairs that will fit, thus it can be treated
* as partial success, in that a new attribute extent needs to be created or
* the next extent has to be used and the mapping pairs build has to be
* continued with @first_vcn set to *@stop_vcn.
*
* Return 0 on success and -errno on error. The following error codes are
* defined:
* -EINVAL - Run list contains unmapped elements. Make sure to only pass
* fully mapped runlists to this function.
* -EIO - The runlist is corrupt.
* -ENOSPC - The destination buffer is too small.
*
* Locking: @rl must be locked on entry (either for reading or writing), it
* remains locked throughout, and is left locked upon return.
*/
int ntfs_mapping_pairs_build(const ntfs_volume *vol, s8 *dst,
const int dst_len, const runlist_element *rl,
const VCN first_vcn, const VCN last_vcn, VCN *const stop_vcn)
{
LCN prev_lcn;
s8 *dst_max, *dst_next;
int err = -ENOSPC;
bool the_end = false;
s8 len_len, lcn_len;
BUG_ON(first_vcn < 0);
BUG_ON(last_vcn < -1);
BUG_ON(last_vcn >= 0 && first_vcn > last_vcn);
BUG_ON(dst_len < 1);
if (!rl) {
BUG_ON(first_vcn);
BUG_ON(last_vcn > 0);
if (stop_vcn)
*stop_vcn = 0;
/* Terminator byte. */
*dst = 0;
return 0;
}
/* Skip to runlist element containing @first_vcn. */
while (rl->length && first_vcn >= rl[1].vcn)
rl++;
if (unlikely((!rl->length && first_vcn > rl->vcn) ||
first_vcn < rl->vcn))
return -EINVAL;
/*
* @dst_max is used for bounds checking in
* ntfs_write_significant_bytes().
*/
dst_max = dst + dst_len - 1;
prev_lcn = 0;
/* Do the first partial run if present. */
if (first_vcn > rl->vcn) {
s64 delta, length = rl->length;
/* We know rl->length != 0 already. */
if (unlikely(length < 0 || rl->lcn < LCN_HOLE))
goto err_out;
/*
* If @stop_vcn is given and finishes inside this run, cap the
* run length.
*/
if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) {
s64 s1 = last_vcn + 1;
if (unlikely(rl[1].vcn > s1))
length = s1 - rl->vcn;
the_end = true;
}
delta = first_vcn - rl->vcn;
/* Write length. */
len_len = ntfs_write_significant_bytes(dst + 1, dst_max,
length - delta);
if (unlikely(len_len < 0))
goto size_err;
/*
* If the logical cluster number (lcn) denotes a hole and we
* are on NTFS 3.0+, we don't store it at all, i.e. we need
* zero space. On earlier NTFS versions we just write the lcn
* change. FIXME: Do we need to write the lcn change or just
* the lcn in that case? Not sure as I have never seen this
* case on NT4. - We assume that we just need to write the lcn
* change until someone tells us otherwise... (AIA)
*/
if (likely(rl->lcn >= 0 || vol->major_ver < 3)) {
prev_lcn = rl->lcn;
if (likely(rl->lcn >= 0))
prev_lcn += delta;
/* Write change in lcn. */
lcn_len = ntfs_write_significant_bytes(dst + 1 +
len_len, dst_max, prev_lcn);
if (unlikely(lcn_len < 0))
goto size_err;
} else
lcn_len = 0;
dst_next = dst + len_len + lcn_len + 1;
if (unlikely(dst_next > dst_max))
goto size_err;
/* Update header byte. */
*dst = lcn_len << 4 | len_len;
/* Position at next mapping pairs array element. */
dst = dst_next;
/* Go to next runlist element. */
rl++;
}
/* Do the full runs. */
for (; rl->length && !the_end; rl++) {
s64 length = rl->length;
if (unlikely(length < 0 || rl->lcn < LCN_HOLE))
goto err_out;
/*
* If @stop_vcn is given and finishes inside this run, cap the
* run length.
*/
if (unlikely(last_vcn >= 0 && rl[1].vcn > last_vcn)) {
s64 s1 = last_vcn + 1;
if (unlikely(rl[1].vcn > s1))
length = s1 - rl->vcn;
the_end = true;
}
/* Write length. */
len_len = ntfs_write_significant_bytes(dst + 1, dst_max,
length);
if (unlikely(len_len < 0))
goto size_err;
/*
* If the logical cluster number (lcn) denotes a hole and we
* are on NTFS 3.0+, we don't store it at all, i.e. we need
* zero space. On earlier NTFS versions we just write the lcn
* change. FIXME: Do we need to write the lcn change or just
* the lcn in that case? Not sure as I have never seen this
* case on NT4. - We assume that we just need to write the lcn
* change until someone tells us otherwise... (AIA)
*/
if (likely(rl->lcn >= 0 || vol->major_ver < 3)) {
/* Write change in lcn. */
lcn_len = ntfs_write_significant_bytes(dst + 1 +
len_len, dst_max, rl->lcn - prev_lcn);
if (unlikely(lcn_len < 0))
goto size_err;
prev_lcn = rl->lcn;
} else
lcn_len = 0;
dst_next = dst + len_len + lcn_len + 1;
if (unlikely(dst_next > dst_max))
goto size_err;
/* Update header byte. */
*dst = lcn_len << 4 | len_len;
/* Position at next mapping pairs array element. */
dst = dst_next;
}
/* Success. */
err = 0;
size_err:
/* Set stop vcn. */
if (stop_vcn)
*stop_vcn = rl->vcn;
/* Add terminator byte. */
*dst = 0;
return err;
err_out:
if (rl->lcn == LCN_RL_NOT_MAPPED)
err = -EINVAL;
else
err = -EIO;
return err;
}
/**
* ntfs_rl_truncate_nolock - truncate a runlist starting at a specified vcn
* @vol: ntfs volume (needed for error output)
* @runlist: runlist to truncate
* @new_length: the new length of the runlist in VCNs
*
* Truncate the runlist described by @runlist as well as the memory buffer
* holding the runlist elements to a length of @new_length VCNs.
*
* If @new_length lies within the runlist, the runlist elements with VCNs of
* @new_length and above are discarded. As a special case if @new_length is
* zero, the runlist is discarded and set to NULL.
*
* If @new_length lies beyond the runlist, a sparse runlist element is added to
* the end of the runlist @runlist or if the last runlist element is a sparse
* one already, this is extended.
*
* Note, no checking is done for unmapped runlist elements. It is assumed that
* the caller has mapped any elements that need to be mapped already.
*
* Return 0 on success and -errno on error.
*
* Locking: The caller must hold @runlist->lock for writing.
*/
int ntfs_rl_truncate_nolock(const ntfs_volume *vol, runlist *const runlist,
const s64 new_length)
{
runlist_element *rl;
int old_size;
ntfs_debug("Entering for new_length 0x%llx.", (long long)new_length);
BUG_ON(!runlist);
BUG_ON(new_length < 0);
rl = runlist->rl;
if (!new_length) {
ntfs_debug("Freeing runlist.");
runlist->rl = NULL;
if (rl)
ntfs_free(rl);
return 0;
}
if (unlikely(!rl)) {
/*
* Create a runlist consisting of a sparse runlist element of
* length @new_length followed by a terminator runlist element.
*/
rl = ntfs_malloc_nofs(PAGE_SIZE);
if (unlikely(!rl)) {
ntfs_error(vol->sb, "Not enough memory to allocate "
"runlist element buffer.");
return -ENOMEM;
}
runlist->rl = rl;
rl[1].length = rl->vcn = 0;
rl->lcn = LCN_HOLE;
rl[1].vcn = rl->length = new_length;
rl[1].lcn = LCN_ENOENT;
return 0;
}
BUG_ON(new_length < rl->vcn);
/* Find @new_length in the runlist. */
while (likely(rl->length && new_length >= rl[1].vcn))
rl++;
/*
* If not at the end of the runlist we need to shrink it.
* If at the end of the runlist we need to expand it.
*/
if (rl->length) {
runlist_element *trl;
bool is_end;
ntfs_debug("Shrinking runlist.");
/* Determine the runlist size. */
trl = rl + 1;
while (likely(trl->length))
trl++;
old_size = trl - runlist->rl + 1;
/* Truncate the run. */
rl->length = new_length - rl->vcn;
/*
* If a run was partially truncated, make the following runlist
* element a terminator.
*/
is_end = false;
if (rl->length) {
rl++;
if (!rl->length)
is_end = true;
rl->vcn = new_length;
rl->length = 0;
}
rl->lcn = LCN_ENOENT;
/* Reallocate memory if necessary. */
if (!is_end) {
int new_size = rl - runlist->rl + 1;
rl = ntfs_rl_realloc(runlist->rl, old_size, new_size);
if (IS_ERR(rl))
ntfs_warning(vol->sb, "Failed to shrink "
"runlist buffer. This just "
"wastes a bit of memory "
"temporarily so we ignore it "
"and return success.");
else
runlist->rl = rl;
}
} else if (likely(/* !rl->length && */ new_length > rl->vcn)) {
ntfs_debug("Expanding runlist.");
/*
* If there is a previous runlist element and it is a sparse
* one, extend it. Otherwise need to add a new, sparse runlist
* element.
*/
if ((rl > runlist->rl) && ((rl - 1)->lcn == LCN_HOLE))
(rl - 1)->length = new_length - (rl - 1)->vcn;
else {
/* Determine the runlist size. */
old_size = rl - runlist->rl + 1;
/* Reallocate memory if necessary. */
rl = ntfs_rl_realloc(runlist->rl, old_size,
old_size + 1);
if (IS_ERR(rl)) {
ntfs_error(vol->sb, "Failed to expand runlist "
"buffer, aborting.");
return PTR_ERR(rl);
}
runlist->rl = rl;
/*
* Set @rl to the same runlist element in the new
* runlist as before in the old runlist.
*/
rl += old_size - 1;
/* Add a new, sparse runlist element. */
rl->lcn = LCN_HOLE;
rl->length = new_length - rl->vcn;
/* Add a new terminator runlist element. */
rl++;
rl->length = 0;
}
rl->vcn = new_length;
rl->lcn = LCN_ENOENT;
} else /* if (unlikely(!rl->length && new_length == rl->vcn)) */ {
/* Runlist already has same size as requested. */
rl->lcn = LCN_ENOENT;
}
ntfs_debug("Done.");
return 0;
}
/**
* ntfs_rl_punch_nolock - punch a hole into a runlist
* @vol: ntfs volume (needed for error output)
* @runlist: runlist to punch a hole into
* @start: starting VCN of the hole to be created
* @length: size of the hole to be created in units of clusters
*
* Punch a hole into the runlist @runlist starting at VCN @start and of size
* @length clusters.
*
* Return 0 on success and -errno on error, in which case @runlist has not been
* modified.
*
* If @start and/or @start + @length are outside the runlist return error code
* -ENOENT.
*
* If the runlist contains unmapped or error elements between @start and @start
* + @length return error code -EINVAL.
*
* Locking: The caller must hold @runlist->lock for writing.
*/
int ntfs_rl_punch_nolock(const ntfs_volume *vol, runlist *const runlist,
const VCN start, const s64 length)
{
const VCN end = start + length;
s64 delta;
runlist_element *rl, *rl_end, *rl_real_end, *trl;
int old_size;
bool lcn_fixup = false;
ntfs_debug("Entering for start 0x%llx, length 0x%llx.",
(long long)start, (long long)length);
BUG_ON(!runlist);
BUG_ON(start < 0);
BUG_ON(length < 0);
BUG_ON(end < 0);
rl = runlist->rl;
if (unlikely(!rl)) {
if (likely(!start && !length))
return 0;
return -ENOENT;
}
/* Find @start in the runlist. */
while (likely(rl->length && start >= rl[1].vcn))
rl++;
rl_end = rl;
/* Find @end in the runlist. */
while (likely(rl_end->length && end >= rl_end[1].vcn)) {
/* Verify there are no unmapped or error elements. */
if (unlikely(rl_end->lcn < LCN_HOLE))
return -EINVAL;
rl_end++;
}
/* Check the last element. */
if (unlikely(rl_end->length && rl_end->lcn < LCN_HOLE))
return -EINVAL;
/* This covers @start being out of bounds, too. */
if (!rl_end->length && end > rl_end->vcn)
return -ENOENT;
if (!length)
return 0;
if (!rl->length)
return -ENOENT;
rl_real_end = rl_end;
/* Determine the runlist size. */
while (likely(rl_real_end->length))
rl_real_end++;
old_size = rl_real_end - runlist->rl + 1;
/* If @start is in a hole simply extend the hole. */
if (rl->lcn == LCN_HOLE) {
/*
* If both @start and @end are in the same sparse run, we are
* done.
*/
if (end <= rl[1].vcn) {
ntfs_debug("Done (requested hole is already sparse).");
return 0;
}
extend_hole:
/* Extend the hole. */
rl->length = end - rl->vcn;
/* If @end is in a hole, merge it with the current one. */
if (rl_end->lcn == LCN_HOLE) {
rl_end++;
rl->length = rl_end->vcn - rl->vcn;
}
/* We have done the hole. Now deal with the remaining tail. */
rl++;
/* Cut out all runlist elements up to @end. */
if (rl < rl_end)
memmove(rl, rl_end, (rl_real_end - rl_end + 1) *
sizeof(*rl));
/* Adjust the beginning of the tail if necessary. */
if (end > rl->vcn) {
delta = end - rl->vcn;
rl->vcn = end;
rl->length -= delta;
/* Only adjust the lcn if it is real. */
if (rl->lcn >= 0)
rl->lcn += delta;
}
shrink_allocation:
/* Reallocate memory if the allocation changed. */
if (rl < rl_end) {
rl = ntfs_rl_realloc(runlist->rl, old_size,
old_size - (rl_end - rl));
if (IS_ERR(rl))
ntfs_warning(vol->sb, "Failed to shrink "
"runlist buffer. This just "
"wastes a bit of memory "
"temporarily so we ignore it "
"and return success.");
else
runlist->rl = rl;
}
ntfs_debug("Done (extend hole).");
return 0;
}
/*
* If @start is at the beginning of a run things are easier as there is
* no need to split the first run.
*/
if (start == rl->vcn) {
/*
* @start is at the beginning of a run.
*
* If the previous run is sparse, extend its hole.
*
* If @end is not in the same run, switch the run to be sparse
* and extend the newly created hole.
*
* Thus both of these cases reduce the problem to the above
* case of "@start is in a hole".
*/
if (rl > runlist->rl && (rl - 1)->lcn == LCN_HOLE) {
rl--;
goto extend_hole;
}
if (end >= rl[1].vcn) {
rl->lcn = LCN_HOLE;
goto extend_hole;
}
/*
* The final case is when @end is in the same run as @start.
* For this need to split the run into two. One run for the
* sparse region between the beginning of the old run, i.e.
* @start, and @end and one for the remaining non-sparse
* region, i.e. between @end and the end of the old run.
*/
trl = ntfs_rl_realloc(runlist->rl, old_size, old_size + 1);
if (IS_ERR(trl))
goto enomem_out;
old_size++;
if (runlist->rl != trl) {
rl = trl + (rl - runlist->rl);
rl_end = trl + (rl_end - runlist->rl);
rl_real_end = trl + (rl_real_end - runlist->rl);
runlist->rl = trl;
}
split_end:
/* Shift all the runs up by one. */
memmove(rl + 1, rl, (rl_real_end - rl + 1) * sizeof(*rl));
/* Finally, setup the two split runs. */
rl->lcn = LCN_HOLE;
rl->length = length;
rl++;
rl->vcn += length;
/* Only adjust the lcn if it is real. */
if (rl->lcn >= 0 || lcn_fixup)
rl->lcn += length;
rl->length -= length;
ntfs_debug("Done (split one).");
return 0;
}
/*
* @start is neither in a hole nor at the beginning of a run.
*
* If @end is in a hole, things are easier as simply truncating the run
* @start is in to end at @start - 1, deleting all runs after that up
* to @end, and finally extending the beginning of the run @end is in
* to be @start is all that is needed.
*/
if (rl_end->lcn == LCN_HOLE) {
/* Truncate the run containing @start. */
rl->length = start - rl->vcn;
rl++;
/* Cut out all runlist elements up to @end. */
if (rl < rl_end)
memmove(rl, rl_end, (rl_real_end - rl_end + 1) *
sizeof(*rl));
/* Extend the beginning of the run @end is in to be @start. */
rl->vcn = start;
rl->length = rl[1].vcn - start;
goto shrink_allocation;
}
/*
* If @end is not in a hole there are still two cases to distinguish.
* Either @end is or is not in the same run as @start.
*
* The second case is easier as it can be reduced to an already solved
* problem by truncating the run @start is in to end at @start - 1.
* Then, if @end is in the next run need to split the run into a sparse
* run followed by a non-sparse run (already covered above) and if @end
* is not in the next run switching it to be sparse, again reduces the
* problem to the already covered case of "@start is in a hole".
*/
if (end >= rl[1].vcn) {
/*
* If @end is not in the next run, reduce the problem to the
* case of "@start is in a hole".
*/
if (rl[1].length && end >= rl[2].vcn) {
/* Truncate the run containing @start. */
rl->length = start - rl->vcn;
rl++;
rl->vcn = start;
rl->lcn = LCN_HOLE;
goto extend_hole;
}
trl = ntfs_rl_realloc(runlist->rl, old_size, old_size + 1);
if (IS_ERR(trl))
goto enomem_out;
old_size++;
if (runlist->rl != trl) {
rl = trl + (rl - runlist->rl);
rl_end = trl + (rl_end - runlist->rl);
rl_real_end = trl + (rl_real_end - runlist->rl);
runlist->rl = trl;
}
/* Truncate the run containing @start. */
rl->length = start - rl->vcn;
rl++;
/*
* @end is in the next run, reduce the problem to the case
* where "@start is at the beginning of a run and @end is in
* the same run as @start".
*/
delta = rl->vcn - start;
rl->vcn = start;
if (rl->lcn >= 0) {
rl->lcn -= delta;
/* Need this in case the lcn just became negative. */
lcn_fixup = true;
}
rl->length += delta;
goto split_end;
}
/*
* The first case from above, i.e. @end is in the same run as @start.
* We need to split the run into three. One run for the non-sparse
* region between the beginning of the old run and @start, one for the
* sparse region between @start and @end, and one for the remaining
* non-sparse region, i.e. between @end and the end of the old run.
*/
trl = ntfs_rl_realloc(runlist->rl, old_size, old_size + 2);
if (IS_ERR(trl))
goto enomem_out;
old_size += 2;
if (runlist->rl != trl) {
rl = trl + (rl - runlist->rl);
rl_end = trl + (rl_end - runlist->rl);
rl_real_end = trl + (rl_real_end - runlist->rl);
runlist->rl = trl;
}
/* Shift all the runs up by two. */
memmove(rl + 2, rl, (rl_real_end - rl + 1) * sizeof(*rl));
/* Finally, setup the three split runs. */
rl->length = start - rl->vcn;
rl++;
rl->vcn = start;
rl->lcn = LCN_HOLE;
rl->length = length;
rl++;
delta = end - rl->vcn;
rl->vcn = end;
rl->lcn += delta;
rl->length -= delta;
ntfs_debug("Done (split both).");
return 0;
enomem_out:
ntfs_error(vol->sb, "Not enough memory to extend runlist buffer.");
return -ENOMEM;
}
#endif /* NTFS_RW */