Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs

Pull second set of btrfs updates from Chris Mason:
 "The most important changes here are from Josef, fixing a btrfs
  regression in 3.14 that can cause corruptions in the extent allocation
  tree when snapshots are in use.

  Josef also fixed some deadlocks in send/recv and other assorted races
  when balance is running"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs: (23 commits)
  Btrfs: fix compile warnings on on avr32 platform
  btrfs: allow mounting btrfs subvolumes with different ro/rw options
  btrfs: export global block reserve size as space_info
  btrfs: fix crash in remount(thread_pool=) case
  Btrfs: abort the transaction when we don't find our extent ref
  Btrfs: fix EINVAL checks in btrfs_clone
  Btrfs: fix unlock in __start_delalloc_inodes()
  Btrfs: scrub raid56 stripes in the right way
  Btrfs: don't compress for a small write
  Btrfs: more efficient io tree navigation on wait_extent_bit
  Btrfs: send, build path string only once in send_hole
  btrfs: filter invalid arg for btrfs resize
  Btrfs: send, fix data corruption due to incorrect hole detection
  Btrfs: kmalloc() doesn't return an ERR_PTR
  Btrfs: fix snapshot vs nocow writting
  btrfs: Change the expanding write sequence to fix snapshot related bug.
  btrfs: make device scan less noisy
  btrfs: fix lockdep warning with reclaim lock inversion
  Btrfs: hold the commit_root_sem when getting the commit root during send
  Btrfs: remove transaction from send
  ...

fs/btrfs/inode.c

@@ -394,6 +394,14 @@ static noinline int compress_file_range(struct inode *inode,
 	    (start > 0 || end + 1 < BTRFS_I(inode)->disk_i_size))
 		btrfs_add_inode_defrag(NULL, inode);
 
+	/*
+	 * skip compression for a small file range(<=blocksize) that
+	 * isn't an inline extent, since it dosen't save disk space at all.
+	 */
+	if ((end - start + 1) <= blocksize &&
+	    (start > 0 || end + 1 < BTRFS_I(inode)->disk_i_size))
+		goto cleanup_and_bail_uncompressed;
+
 	actual_end = min_t(u64, isize, end + 1);
 again:
 	will_compress = 0;
@@ -1270,6 +1278,15 @@ next_slot:
 			disk_bytenr += extent_offset;
 			disk_bytenr += cur_offset - found_key.offset;
 			num_bytes = min(end + 1, extent_end) - cur_offset;
+			/*
+			 * if there are pending snapshots for this root,
+			 * we fall into common COW way.
+			 */
+			if (!nolock) {
+				err = btrfs_start_nocow_write(root);
+				if (!err)
+					goto out_check;
+			}
 			/*
 			 * force cow if csum exists in the range.
 			 * this ensure that csum for a given extent are
@@ -1289,6 +1306,8 @@ next_slot:
 out_check:
 		if (extent_end <= start) {
 			path->slots[0]++;
+			if (!nolock && nocow)
+				btrfs_end_nocow_write(root);
 			goto next_slot;
 		}
 		if (!nocow) {
@@ -1306,8 +1325,11 @@ out_check:
 			ret = cow_file_range(inode, locked_page,
 					     cow_start, found_key.offset - 1,
 					     page_started, nr_written, 1);
-			if (ret)
+			if (ret) {
+				if (!nolock && nocow)
+					btrfs_end_nocow_write(root);
 				goto error;
+			}
 			cow_start = (u64)-1;
 		}
 
@@ -1354,8 +1376,11 @@ out_check:
 		    BTRFS_DATA_RELOC_TREE_OBJECTID) {
 			ret = btrfs_reloc_clone_csums(inode, cur_offset,
 						      num_bytes);
-			if (ret)
+			if (ret) {
+				if (!nolock && nocow)
+					btrfs_end_nocow_write(root);
 				goto error;
+			}
 		}
 
 		extent_clear_unlock_delalloc(inode, cur_offset,
@@ -1363,6 +1388,8 @@ out_check:
 					     locked_page, EXTENT_LOCKED |
 					     EXTENT_DELALLOC, PAGE_UNLOCK |
 					     PAGE_SET_PRIVATE2);
+		if (!nolock && nocow)
+			btrfs_end_nocow_write(root);
 		cur_offset = extent_end;
 		if (cur_offset > end)
 			break;
@@ -8476,19 +8503,20 @@ static int __start_delalloc_inodes(struct btrfs_root *root, int delay_iput,
 			else
 				iput(inode);
 			ret = -ENOMEM;
-			break;
+			goto out;
 		}
 		list_add_tail(&work->list, &works);
 		btrfs_queue_work(root->fs_info->flush_workers,
 				 &work->work);
 		ret++;
 		if (nr != -1 && ret >= nr)
-			break;
+			goto out;
 		cond_resched();
 		spin_lock(&root->delalloc_lock);
 	}
 	spin_unlock(&root->delalloc_lock);
 
+out:
 	list_for_each_entry_safe(work, next, &works, list) {
 		list_del_init(&work->list);
 		btrfs_wait_and_free_delalloc_work(work);