NTFS: More runlist handling fixes from Richard Russon and myself.
Signed-off-by: Anton Altaparmakov <aia21@cantab.net>
diff --git a/fs/ntfs/runlist.c b/fs/ntfs/runlist.c
index e2665d0..061b5ff 100644
--- a/fs/ntfs/runlist.c
+++ b/fs/ntfs/runlist.c
@@ -158,17 +158,21 @@
BUG_ON(!dst);
BUG_ON(!src);
- if ((dst->lcn < 0) || (src->lcn < 0)) { /* Are we merging holes? */
- if (dst->lcn == LCN_HOLE && src->lcn == LCN_HOLE)
- return TRUE;
+ /* 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 ((dst->lcn + dst->length) != src->lcn) /* Are the runs contiguous? */
- return FALSE;
- if ((dst->vcn + dst->length) != src->vcn) /* Are the runs misaligned? */
- return FALSE;
-
- return TRUE;
+ /* 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;
}
/**
@@ -214,14 +218,15 @@
static inline runlist_element *ntfs_rl_append(runlist_element *dst,
int dsize, runlist_element *src, int ssize, int loc)
{
- BOOL right; /* Right end of @src needs merging. */
- int marker; /* End of the inserted runs. */
+ 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. */
- right = ntfs_are_rl_mergeable(src + ssize - 1, dst + loc + 1);
+ 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);
@@ -377,20 +382,21 @@
int dsize, runlist_element *src, int ssize, int loc)
{
BOOL left = FALSE; /* Left end of @src needs merging. */
- BOOL right; /* Right 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, merge the left and right ends, if necessary. */
- right = ntfs_are_rl_mergeable(src + ssize - 1, dst + loc + 1);
+ /* 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 were merged.
+ * ends get merged.
*/
dst = ntfs_rl_realloc(dst, dsize, dsize + ssize - left - right);
if (IS_ERR(dst))
@@ -399,21 +405,26 @@
* 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);
/*
- * 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.
+ * 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
+ * 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;