diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index e5f19b49efa804fe02752b6c8f676eafe3853dd0..6d9f81d4e99c09f7373f963120bd0f79e98cb9cf 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -229,6 +229,13 @@ struct btrfs_root_backup {
 #define BTRFS_SUPER_INFO_OFFSET			SZ_64K
 #define BTRFS_SUPER_INFO_SIZE			4096
 
+/*
+ * The reserved space at the beginning of each device.
+ * It covers the primary super block and leaves space for potential use by other
+ * tools like bootloaders or to lower potential damage of accidental overwrite.
+ */
+#define BTRFS_DEVICE_RANGE_RESERVED			(SZ_1M)
+
 /*
  * the super block basically lists the main trees of the FS
  * it currently lacks any block count etc etc
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 91d2c20c7c8a6f20bfcf436941e6efacf19d80f6..a1696e3ffb1e38277318fa3f3e867d2f1e00084d 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -5976,7 +5976,7 @@ int btrfs_error_unpin_extent_range(struct btrfs_fs_info *fs_info,
  */
 static int btrfs_trim_free_extents(struct btrfs_device *device, u64 *trimmed)
 {
-	u64 start = SZ_1M, len = 0, end = 0;
+	u64 start = BTRFS_DEVICE_RANGE_RESERVED, len = 0, end = 0;
 	int ret;
 
 	*trimmed = 0;
@@ -6020,8 +6020,8 @@ static int btrfs_trim_free_extents(struct btrfs_device *device, u64 *trimmed)
 			break;
 		}
 
-		/* Ensure we skip the reserved area in the first 1M */
-		start = max_t(u64, start, SZ_1M);
+		/* Ensure we skip the reserved space on each device. */
+		start = max_t(u64, start, BTRFS_DEVICE_RANGE_RESERVED);
 
 		/*
 		 * If find_first_clear_extent_bit find a range that spans the
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 719dda57dc7a0a1c2a575ab0eb544c8657948874..41652dcd16f436eeb2142cb1fc89ee17c37c8634 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -2272,17 +2272,13 @@ static inline int btrfs_calc_avail_data_space(struct btrfs_fs_info *fs_info,
 		avail_space = rounddown(avail_space, BTRFS_STRIPE_LEN);
 
 		/*
-		 * In order to avoid overwriting the superblock on the drive,
-		 * btrfs starts at an offset of at least 1MB when doing chunk
-		 * allocation.
-		 *
-		 * This ensures we have at least min_stripe_size free space
-		 * after excluding 1MB.
+		 * Ensure we have at least min_stripe_size on top of the
+		 * reserved space on the device.
 		 */
-		if (avail_space <= SZ_1M + min_stripe_size)
+		if (avail_space <= BTRFS_DEVICE_RANGE_RESERVED + min_stripe_size)
 			continue;
 
-		avail_space -= SZ_1M;
+		avail_space -= BTRFS_DEVICE_RANGE_RESERVED;
 
 		devices_info[i].dev = device;
 		devices_info[i].max_avail = avail_space;
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 80636fbf28b7a3f46d4d134e49580532bbf5853b..e6af960a69614fea94cf070e28453fcb7718a3f3 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1403,12 +1403,7 @@ static u64 dev_extent_search_start(struct btrfs_device *device, u64 start)
 {
 	switch (device->fs_devices->chunk_alloc_policy) {
 	case BTRFS_CHUNK_ALLOC_REGULAR:
-		/*
-		 * We don't want to overwrite the superblock on the drive nor
-		 * any area used by the boot loader (grub for example), so we
-		 * make sure to start at an offset of at least 1MB.
-		 */
-		return max_t(u64, start, SZ_1M);
+		return max_t(u64, start, BTRFS_DEVICE_RANGE_RESERVED);
 	case BTRFS_CHUNK_ALLOC_ZONED:
 		/*
 		 * We don't care about the starting region like regular