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-rw-r--r--fs/ntfs/runlist.c35
1 files changed, 35 insertions, 0 deletions
diff --git a/fs/ntfs/runlist.c b/fs/ntfs/runlist.c
index 3f479f17661..396d767c2ca 100644
--- a/fs/ntfs/runlist.c
+++ b/fs/ntfs/runlist.c
@@ -980,6 +980,39 @@ LCN ntfs_rl_vcn_to_lcn(const runlist_element *rl, const VCN vcn)
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
@@ -1452,3 +1485,5 @@ int ntfs_rl_truncate_nolock(const ntfs_volume *vol, runlist *const runlist,
ntfs_debug("Done.");
return 0;
}
+
+#endif /* NTFS_RW */