1 files changed, 47 insertions, 9 deletions

diff --git a/fs/ntfs/lcnalloc.c b/fs/ntfs/lcnalloc.c
index 5af3bf0b7eee..29cabf93d2d2 100644
--- a/fs/ntfs/lcnalloc.c
+++ b/fs/ntfs/lcnalloc.c
@@ -76,6 +76,7 @@ int ntfs_cluster_free_from_rl_nolock(ntfs_volume *vol,
  * @count:      number of clusters to allocate
  * @start_lcn:  starting lcn at which to allocate the clusters (or -1 if none)
  * @zone:       zone from which to allocate the clusters
+ * @is_extension:       if TRUE, this is an attribute extension
  *
  * Allocate @count clusters preferably starting at cluster @start_lcn or at the
  * current allocator position if @start_lcn is -1, on the mounted ntfs volume
@@ -86,6 +87,13 @@ int ntfs_cluster_free_from_rl_nolock(ntfs_volume *vol,
  * @start_vcn specifies the vcn of the first allocated cluster.  This makes
  * merging the resulting runlist with the old runlist easier.
  *
+ * If @is_extension is TRUE, the caller is allocating clusters to extend an
+ * attribute and if it is FALSE, the caller is allocating clusters to fill a
+ * hole in an attribute.  Practically the difference is that if @is_extension
+ * is TRUE the returned runlist will be terminated with LCN_ENOENT and if
+ * @is_extension is FALSE the runlist will be terminated with
+ * LCN_RL_NOT_MAPPED.
+ *
  * You need to check the return value with IS_ERR().  If this is false, the
  * function was successful and the return value is a runlist describing the
  * allocated cluster(s).  If IS_ERR() is true, the function failed and
@@ -137,7 +145,8 @@ int ntfs_cluster_free_from_rl_nolock(ntfs_volume *vol,
  */
 runlist_element *ntfs_cluster_alloc(ntfs_volume *vol, const VCN start_vcn,
                 const s64 count, const LCN start_lcn,
-                const NTFS_CLUSTER_ALLOCATION_ZONES zone)
+                const NTFS_CLUSTER_ALLOCATION_ZONES zone,
+                const BOOL is_extension)
 {
         LCN zone_start, zone_end, bmp_pos, bmp_initial_pos, last_read_pos, lcn;
         LCN prev_lcn = 0, prev_run_len = 0, mft_zone_size;
@@ -310,7 +319,7 @@ runlist_element *ntfs_cluster_alloc(ntfs_volume *vol, const VCN start_vcn,
                                 continue;
                         }
                         bit = 1 << (lcn & 7);
-                        ntfs_debug("bit %i.", bit);
+                        ntfs_debug("bit 0x%x.", bit);
                         /* If the bit is already set, go onto the next one. */
                         if (*byte & bit) {
                                 lcn++;
@@ -729,7 +738,7 @@ out:
         /* Add runlist terminator element. */
         if (likely(rl)) {
                 rl[rlpos].vcn = rl[rlpos - 1].vcn + rl[rlpos - 1].length;
-                rl[rlpos].lcn = LCN_RL_NOT_MAPPED;
+                rl[rlpos].lcn = is_extension ? LCN_ENOENT : LCN_RL_NOT_MAPPED;
                 rl[rlpos].length = 0;
         }
         if (likely(page && !IS_ERR(page))) {
@@ -782,6 +791,7 @@ out:
  * @ni:         ntfs inode whose runlist describes the clusters to free
  * @start_vcn:  vcn in the runlist of @ni at which to start freeing clusters
  * @count:      number of clusters to free or -1 for all clusters
+ * @ctx:        active attribute search context if present or NULL if not
  * @is_rollback:        true if this is a rollback operation
  *
  * Free @count clusters starting at the cluster @start_vcn in the runlist
@@ -791,15 +801,39 @@ out:
  * deallocated.  Thus, to completely free all clusters in a runlist, use
  * @start_vcn = 0 and @count = -1.
  *
+ * If @ctx is specified, it is an active search context of @ni and its base mft
+ * record.  This is needed when __ntfs_cluster_free() encounters unmapped
+ * runlist fragments and allows their mapping.  If you do not have the mft
+ * record mapped, you can specify @ctx as NULL and __ntfs_cluster_free() will
+ * perform the necessary mapping and unmapping.
+ *
+ * Note, __ntfs_cluster_free() saves the state of @ctx on entry and restores it
+ * before returning.  Thus, @ctx will be left pointing to the same attribute on
+ * return as on entry.  However, the actual pointers in @ctx may point to
+ * different memory locations on return, so you must remember to reset any
+ * cached pointers from the @ctx, i.e. after the call to __ntfs_cluster_free(),
+ * you will probably want to do:
+ *      m = ctx->mrec;
+ *      a = ctx->attr;
+ * Assuming you cache ctx->attr in a variable @a of type ATTR_RECORD * and that
+ * you cache ctx->mrec in a variable @m of type MFT_RECORD *.
+ *
  * @is_rollback should always be FALSE, it is for internal use to rollback
  * errors.  You probably want to use ntfs_cluster_free() instead.
  *
- * Note, ntfs_cluster_free() does not modify the runlist at all, so the caller
- * has to deal with it later.
+ * Note, __ntfs_cluster_free() does not modify the runlist, so you have to
+ * remove from the runlist or mark sparse the freed runs later.
  *
  * Return the number of deallocated clusters (not counting sparse ones) on
  * success and -errno on error.
  *
+ * WARNING: If @ctx is supplied, regardless of whether success or failure is
+ *          returned, you need to check IS_ERR(@ctx->mrec) and if TRUE the @ctx
+ *          is no longer valid, i.e. you need to either call
+ *          ntfs_attr_reinit_search_ctx() or ntfs_attr_put_search_ctx() on it.
+ *          In that case PTR_ERR(@ctx->mrec) will give you the error code for
+ *          why the mapping of the old inode failed.
+ *
  * Locking: - The runlist described by @ni must be locked for writing on entry
  *            and is locked on return.  Note the runlist may be modified when
  *            needed runlist fragments need to be mapped.
@@ -807,9 +841,13 @@ out:
  *            on return.
  *          - This function takes the volume lcn bitmap lock for writing and
  *            modifies the bitmap contents.
+ *          - If @ctx is NULL, the base mft record of @ni must not be mapped on
+ *            entry and it will be left unmapped on return.
+ *          - If @ctx is not NULL, the base mft record must be mapped on entry
+ *            and it will be left mapped on return.
  */
 s64 __ntfs_cluster_free(ntfs_inode *ni, const VCN start_vcn, s64 count,
-                const BOOL is_rollback)
+                ntfs_attr_search_ctx *ctx, const BOOL is_rollback)
 {
         s64 delta, to_free, total_freed, real_freed;
         ntfs_volume *vol;
@@ -839,7 +877,7 @@ s64 __ntfs_cluster_free(ntfs_inode *ni, const VCN start_vcn, s64 count,
 
         total_freed = real_freed = 0;
 
-        rl = ntfs_attr_find_vcn_nolock(ni, start_vcn, TRUE);
+        rl = ntfs_attr_find_vcn_nolock(ni, start_vcn, ctx);
         if (IS_ERR(rl)) {
                 if (!is_rollback)
                         ntfs_error(vol->sb, "Failed to find first runlist "
@@ -893,7 +931,7 @@ s64 __ntfs_cluster_free(ntfs_inode *ni, const VCN start_vcn, s64 count,
 
                         /* Attempt to map runlist. */
                         vcn = rl->vcn;
-                        rl = ntfs_attr_find_vcn_nolock(ni, vcn, TRUE);
+                        rl = ntfs_attr_find_vcn_nolock(ni, vcn, ctx);
                         if (IS_ERR(rl)) {
                                 err = PTR_ERR(rl);
                                 if (!is_rollback)
@@ -961,7 +999,7 @@ err_out:
          * If rollback fails, set the volume errors flag, emit an error
          * message, and return the error code.
          */
-        delta = __ntfs_cluster_free(ni, start_vcn, total_freed, TRUE);
+        delta = __ntfs_cluster_free(ni, start_vcn, total_freed, ctx, TRUE);
         if (delta < 0) {
                 ntfs_error(vol->sb, "Failed to rollback (error %i).  Leaving "
                                 "inconsistent metadata!  Unmount and run "