1 files changed, 26 insertions, 20 deletions

diff --git a/fs/ocfs2/move_extents.c b/fs/ocfs2/move_extents.c
index 800552168d8a..efc509b3af1f 100644
--- a/fs/ocfs2/move_extents.c
+++ b/fs/ocfs2/move_extents.c
@@ -44,6 +44,7 @@ struct ocfs2_move_extents_context {
         struct inode *inode;
         struct file *file;
         int auto_defrag;
+        int partial;
         int credits;
         u32 new_phys_cpos;
         u32 clusters_moved;
@@ -221,9 +222,9 @@ out:
  * crash happens anywhere.
  */
 static int ocfs2_defrag_extent(struct ocfs2_move_extents_context *context,
-                               u32 cpos, u32 phys_cpos, u32 len, int ext_flags)
+                               u32 cpos, u32 phys_cpos, u32 *len, int ext_flags)
 {
-        int ret, credits = 0, extra_blocks = 0;
+        int ret, credits = 0, extra_blocks = 0, partial = context->partial;
         handle_t *handle;
         struct inode *inode = context->inode;
         struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
@@ -232,7 +233,7 @@ static int ocfs2_defrag_extent(struct ocfs2_move_extents_context *context,
         u32 new_phys_cpos, new_len;
         u64 phys_blkno = ocfs2_clusters_to_blocks(inode->i_sb, phys_cpos);
 
-        if ((ext_flags & OCFS2_EXT_REFCOUNTED) && len) {
+        if ((ext_flags & OCFS2_EXT_REFCOUNTED) && *len) {
 
                 BUG_ON(!(OCFS2_I(inode)->ip_dyn_features &
                          OCFS2_HAS_REFCOUNT_FL));
@@ -249,7 +250,7 @@ static int ocfs2_defrag_extent(struct ocfs2_move_extents_context *context,
                 ret = ocfs2_prepare_refcount_change_for_del(inode,
                                                         context->refcount_loc,
                                                         phys_blkno,
-                                                        len,
+                                                        *len,
                                                         &credits,
                                                         &extra_blocks);
                 if (ret) {
@@ -258,7 +259,7 @@ static int ocfs2_defrag_extent(struct ocfs2_move_extents_context *context,
                 }
         }
 
-        ret = ocfs2_lock_allocators_move_extents(inode, &context->et, len, 1,
+        ret = ocfs2_lock_allocators_move_extents(inode, &context->et, *len, 1,
                                                  &context->meta_ac,
                                                  &context->data_ac,
                                                  extra_blocks, &credits);
@@ -291,7 +292,7 @@ static int ocfs2_defrag_extent(struct ocfs2_move_extents_context *context,
                 goto out_unlock_mutex;
         }
 
-        ret = __ocfs2_claim_clusters(handle, context->data_ac, 1, len,
+        ret = __ocfs2_claim_clusters(handle, context->data_ac, 1, *len,
                                      &new_phys_cpos, &new_len);
         if (ret) {
                 mlog_errno(ret);
@@ -299,33 +300,36 @@ static int ocfs2_defrag_extent(struct ocfs2_move_extents_context *context,
         }
 
         /*
-         * we're not quite patient here to make multiple attempts for claiming
-         * enough clusters, failure to claim clusters per-requested is not a
-         * disaster though, it can only mean partial range of defragmentation
-         * or extent movements gets gone, users anyway is able to have another
-         * try as they wish anytime, since they're going to be returned a
-         * '-ENOSPC' and completed length of this movement.
+         * allowing partial extent moving is kind of 'pros and cons', it makes
+         * whole defragmentation less likely to fail, on the contrary, the bad
+         * thing is it may make the fs even more fragmented after moving, let
+         * userspace make a good decision here.
          */
-        if (new_len != len) {
-                mlog(0, "len_claimed: %u, len: %u\n", new_len, len);
-                context->range->me_flags &= ~OCFS2_MOVE_EXT_FL_COMPLETE;
-                ret = -ENOSPC;
-                goto out_commit;
+        if (new_len != *len) {
+                mlog(0, "len_claimed: %u, len: %u\n", new_len, *len);
+                if (!partial) {
+                        context->range->me_flags &= ~OCFS2_MOVE_EXT_FL_COMPLETE;
+                        ret = -ENOSPC;
+                        goto out_commit;
+                }
         }
 
         mlog(0, "cpos: %u, phys_cpos: %u, new_phys_cpos: %u\n", cpos,
              phys_cpos, new_phys_cpos);
 
-        ret = __ocfs2_move_extent(handle, context, cpos, len, phys_cpos,
+        ret = __ocfs2_move_extent(handle, context, cpos, new_len, phys_cpos,
                                   new_phys_cpos, ext_flags);
         if (ret)
                 mlog_errno(ret);
 
+        if (partial && (new_len != *len))
+                *len = new_len;
+
         /*
          * Here we should write the new page out first if we are
          * in write-back mode.
          */
-        ret = ocfs2_cow_sync_writeback(inode->i_sb, context->inode, cpos, len);
+        ret = ocfs2_cow_sync_writeback(inode->i_sb, context->inode, cpos, *len);
         if (ret)
                 mlog_errno(ret);
 
@@ -926,7 +930,7 @@ static int __ocfs2_move_extents_range(struct buffer_head *di_bh,
                              cpos, phys_cpos, alloc_size, len_defraged);
 
                         ret = ocfs2_defrag_extent(context, cpos, phys_cpos,
-                                                  alloc_size, flags);
+                                                  &alloc_size, flags);
                 } else {
                         ret = ocfs2_move_extent(context, cpos, phys_cpos,
                                                 &new_phys_cpos, alloc_size,
@@ -1101,6 +1105,8 @@ int ocfs2_ioctl_move_extents(struct file *filp, void __user *argp)
                          * any thought?
                          */
                         range.me_threshold = 1024 * 1024;
+                if (range.me_flags & OCFS2_MOVE_EXT_FL_PART_DEFRAG)
+                        context->partial = 1;
         } else {
                 /*
                  * first best-effort attempt to validate and adjust the goal