NTFS: Change ntfs_rl_truncate_nolock() to throw away the runlist if the new

      length is zero.

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>

diff --git a/fs/ntfs/ChangeLog b/fs/ntfs/ChangeLog
index 45f806fc45f9146655f3031a283adf7878a5fc2c..79d9899b3b0136a4b01f6e86ccf056e18b1819b3 100644 (file)
--- a/fs/ntfs/ChangeLog
+++ b/fs/ntfs/ChangeLog
@@ -51,6 +51,8 @@ ToDo/Notes:
        - Report unrepresentable inodes during ntfs_readdir() as KERN_WARNING
          messages and include the inode number.  Thanks to Yura Pakhuchiy for
          pointing this out.
+       - Change ntfs_rl_truncate_nolock() to throw away the runlist if the new
+         length is zero.
 
 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 e4c4716939de3d73dbe971bb6c3cd9e5bb4e76d4..539fa2b7f361371041b3fde11952bc3cd215ffb6 100644 (file)
--- a/fs/ntfs/runlist.c
+++ b/fs/ntfs/runlist.c
@@ -1455,6 +1455,7 @@ err_out:
 
 /**
  * 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
  *
@@ -1462,12 +1463,16 @@ err_out:
  * 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.
+ * @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.
@@ -1482,6 +1487,13 @@ int ntfs_rl_truncate_nolock(const ntfs_volume *vol, runlist *const runlist,
        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