NTFS: Add ntfs_rl_punch_nolock() which punches a caller specified hole into a runlist.
Signed-off-by: Anton Altaparmakov <aia21@cantab.net>
diff --git a/fs/ntfs/ChangeLog b/fs/ntfs/ChangeLog
index 79d9899b..39dca6d 100644
--- a/fs/ntfs/ChangeLog
+++ b/fs/ntfs/ChangeLog
@@ -53,6 +53,8 @@
pointing this out.
- Change ntfs_rl_truncate_nolock() to throw away the runlist if the new
length is zero.
+ - Add runlist.[hc]::ntfs_rl_punch_nolock() which punches a caller
+ specified hole into a runlist.
2.1.23 - Implement extension of resident files and make writing safe as well as
many bug fixes, cleanups, and enhancements...
diff --git a/fs/ntfs/runlist.c b/fs/ntfs/runlist.c
index 539fa2b..f5b2ac9 100644
--- a/fs/ntfs/runlist.c
+++ b/fs/ntfs/runlist.c
@@ -1601,4 +1601,288 @@
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) {
+ s64 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 */
diff --git a/fs/ntfs/runlist.h b/fs/ntfs/runlist.h
index aa0ee65..47728fb 100644
--- a/fs/ntfs/runlist.h
+++ b/fs/ntfs/runlist.h
@@ -94,6 +94,9 @@
extern int ntfs_rl_truncate_nolock(const ntfs_volume *vol,
runlist *const runlist, const s64 new_length);
+int ntfs_rl_punch_nolock(const ntfs_volume *vol, runlist *const runlist,
+ const VCN start, const s64 length);
+
#endif /* NTFS_RW */
#endif /* _LINUX_NTFS_RUNLIST_H */