NTFS: Fix various bugs in the runlist merging code. (Based on libntfs

changes by Richard Russon.)

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>
This commit is contained in:
Anton Altaparmakov 2005-09-19 09:33:40 +01:00
parent 065d9cac98
commit 5c9f6de3b8
2 changed files with 70 additions and 64 deletions

View file

@ -92,6 +92,8 @@ ToDo/Notes:
an octal number to conform to how chmod(1) works, too. Thanks to
Giuseppe Bilotta and Horst von Brand for pointing out the errors of
my ways.
- Fix various bugs in the runlist merging code. (Based on libntfs
changes by Richard Russon.)
2.1.23 - Implement extension of resident files and make writing safe as well as
many bug fixes, cleanups, and enhancements...

View file

@ -2,7 +2,7 @@
* runlist.c - NTFS runlist handling code. Part of the Linux-NTFS project.
*
* Copyright (c) 2001-2005 Anton Altaparmakov
* Copyright (c) 2002 Richard Russon
* Copyright (c) 2002-2005 Richard Russon
*
* 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
@ -214,8 +214,8 @@ static inline void __ntfs_rl_merge(runlist_element *dst, runlist_element *src)
static inline runlist_element *ntfs_rl_append(runlist_element *dst,
int dsize, runlist_element *src, int ssize, int loc)
{
BOOL right;
int magic;
BOOL right; /* Right end of @src needs merging. */
int marker; /* End of the inserted runs. */
BUG_ON(!dst);
BUG_ON(!src);
@ -236,18 +236,19 @@ static inline runlist_element *ntfs_rl_append(runlist_element *dst,
if (right)
__ntfs_rl_merge(src + ssize - 1, dst + loc + 1);
magic = loc + ssize;
/* 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, magic + 1, loc + 1 + right, dsize - loc - 1 - right);
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[magic + 1].lcn == LCN_ENOENT)
dst[magic + 1].vcn = dst[magic].vcn + dst[magic].length;
if (dst[marker].lcn == LCN_ENOENT)
dst[marker].vcn = dst[marker - 1].vcn + dst[marker - 1].length;
return dst;
}
@ -279,18 +280,17 @@ static inline runlist_element *ntfs_rl_append(runlist_element *dst,
static inline runlist_element *ntfs_rl_insert(runlist_element *dst,
int dsize, runlist_element *src, int ssize, int loc)
{
BOOL left = FALSE;
BOOL disc = FALSE; /* Discontinuity */
BOOL hole = FALSE; /* Following a hole */
int magic;
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 hole.
* hole => @dst ends with a hole or an unmapped region which we can
* extend to match the discontinuity. */
/*
* 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 {
@ -303,58 +303,49 @@ static inline runlist_element *ntfs_rl_insert(runlist_element *dst,
merged_length += src->length;
disc = (src[0].vcn > dst[loc - 1].vcn + merged_length);
if (disc)
hole = (dst[loc - 1].lcn == LCN_HOLE);
}
/* Space required: @dst size + @src size, less one if we merged, plus
* one if there was a discontinuity, less one for a trailing hole. */
dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - left + disc - hole);
/*
* 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);
magic = loc + ssize - left + disc - hole;
/*
* 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, magic, loc, dsize - loc);
ntfs_rl_mc(dst, loc + disc - hole, src, left, ssize - left);
ntfs_rl_mm(dst, marker, loc, dsize - loc);
ntfs_rl_mc(dst, loc + disc, src, left, ssize - left);
/* Adjust the VCN of the last run ... */
if (dst[magic].lcn <= LCN_HOLE)
dst[magic].vcn = dst[magic - 1].vcn + dst[magic - 1].length;
/* 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[magic].lcn == LCN_HOLE || dst[magic].lcn == LCN_RL_NOT_MAPPED)
dst[magic].length = dst[magic + 1].vcn - dst[magic].vcn;
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's a discontinuity. */
/* Writing beyond the end of the file and there is a discontinuity. */
if (disc) {
if (hole)
dst[loc - 1].length = dst[loc].vcn - dst[loc - 1].vcn;
else {
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;
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;
}
magic += hole;
if (dst[magic].lcn == LCN_ENOENT)
dst[magic].vcn = dst[magic - 1].vcn +
dst[magic - 1].length;
dst[loc].lcn = LCN_RL_NOT_MAPPED;
}
return dst;
}
@ -385,9 +376,10 @@ static inline runlist_element *ntfs_rl_insert(runlist_element *dst,
static inline runlist_element *ntfs_rl_replace(runlist_element *dst,
int dsize, runlist_element *src, int ssize, int loc)
{
BOOL left = FALSE;
BOOL right;
int magic;
BOOL left = FALSE; /* Left end of @src needs merging. */
BOOL right; /* 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);
@ -396,9 +388,10 @@ static inline runlist_element *ntfs_rl_replace(runlist_element *dst,
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'll need less if the left, right, or both
* ends were merged. */
/*
* Allocate some space. We will need less if the left, right, or both
* ends were merged.
*/
dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - left - right);
if (IS_ERR(dst))
return dst;
@ -410,17 +403,28 @@ static inline runlist_element *ntfs_rl_replace(runlist_element *dst,
__ntfs_rl_merge(src + ssize - 1, dst + loc + 1);
if (left)
__ntfs_rl_merge(dst + loc - 1, src);
/* FIXME: What does this mean? (AIA) */
magic = loc + ssize - left;
/*
* First run of @dst that 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.
*/
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, magic, loc + right + 1, dsize - loc - right - 1);
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 (dst[magic].lcn == LCN_ENOENT)
dst[magic].vcn = dst[magic - 1].vcn + dst[magic - 1].length;
/* 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;
}