1 files changed, 16 insertions, 27 deletions

diff --git a/fs/btrfs/block-rsv.c b/fs/btrfs/block-rsv.c
index ec96285357e0..5367a14d44d2 100644
--- a/fs/btrfs/block-rsv.c
+++ b/fs/btrfs/block-rsv.c
@@ -7,6 +7,8 @@
 #include "transaction.h"
 #include "block-group.h"
 #include "disk-io.h"
+#include "fs.h"
+#include "accessors.h"
 
 /*
  * HOW DO BLOCK RESERVES WORK
@@ -225,7 +227,7 @@ int btrfs_block_rsv_add(struct btrfs_fs_info *fs_info,
 	return ret;
 }
 
-int btrfs_block_rsv_check(struct btrfs_block_rsv *block_rsv, int min_factor)
+int btrfs_block_rsv_check(struct btrfs_block_rsv *block_rsv, int min_percent)
 {
 	u64 num_bytes = 0;
 	int ret = -ENOSPC;
@@ -234,7 +236,7 @@ int btrfs_block_rsv_check(struct btrfs_block_rsv *block_rsv, int min_factor)
 		return 0;
 
 	spin_lock(&block_rsv->lock);
-	num_bytes = div_factor(block_rsv->size, min_factor);
+	num_bytes = mult_perc(block_rsv->size, min_percent);
 	if (block_rsv->reserved >= num_bytes)
 		ret = 0;
 	spin_unlock(&block_rsv->lock);
@@ -323,31 +325,6 @@ void btrfs_block_rsv_add_bytes(struct btrfs_block_rsv *block_rsv,
 	spin_unlock(&block_rsv->lock);
 }
 
-int btrfs_cond_migrate_bytes(struct btrfs_fs_info *fs_info,
-			     struct btrfs_block_rsv *dest, u64 num_bytes,
-			     int min_factor)
-{
-	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
-	u64 min_bytes;
-
-	if (global_rsv->space_info != dest->space_info)
-		return -ENOSPC;
-
-	spin_lock(&global_rsv->lock);
-	min_bytes = div_factor(global_rsv->size, min_factor);
-	if (global_rsv->reserved < min_bytes + num_bytes) {
-		spin_unlock(&global_rsv->lock);
-		return -ENOSPC;
-	}
-	global_rsv->reserved -= num_bytes;
-	if (global_rsv->reserved < global_rsv->size)
-		global_rsv->full = false;
-	spin_unlock(&global_rsv->lock);
-
-	btrfs_block_rsv_add_bytes(dest, num_bytes, true);
-	return 0;
-}
-
 void btrfs_update_global_block_rsv(struct btrfs_fs_info *fs_info)
 {
 	struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
@@ -552,5 +529,17 @@ try_reserve:
 		if (!ret)
 			return global_rsv;
 	}
+
+	/*
+	 * All hope is lost, but of course our reservations are overly
+	 * pessimistic, so instead of possibly having an ENOSPC abort here, try
+	 * one last time to force a reservation if there's enough actual space
+	 * on disk to make the reservation.
+	 */
+	ret = btrfs_reserve_metadata_bytes(fs_info, block_rsv, blocksize,
+					   BTRFS_RESERVE_FLUSH_EMERGENCY);
+	if (!ret)
+		return block_rsv;
+
 	return ERR_PTR(ret);
 }