btrfs-progs: mkfs: remove alloc start options and docs

The option -A was used long time ago for debugging and marked as
obsolete since 4.14.1. Remove the option and set the alloc start to the
default value 1MiB.

Signed-off-by: David Sterba <dsterba@suse.com>

Author: kdave

Documentation/mkfs.btrfs.asciidoc

@@ -161,12 +161,6 @@ Print the *mkfs.btrfs* version and exit.
 *--help*::
 Print help.
 
-*-A|--alloc-start <offset>*::
-*deprecated, will be removed*
-(An option to help debugging chunk allocator.)
-Specify the (physical) offset from the start of the device at which allocations
-start.  The default value is zero.
-
 SIZE UNITS
 ----------
 The default unit is 'byte'. All size parameters accept suffixes in the 1024

ctree.h

@@ -1173,7 +1173,6 @@ struct btrfs_fs_info {
 	u64 data_alloc_profile;
 	u64 metadata_alloc_profile;
 	u64 system_alloc_profile;
-	u64 alloc_start;
 
 	struct btrfs_trans_handle *running_transaction;
 	struct btrfs_super_block *super_copy;

mkfs/main.c

@@ -361,7 +361,6 @@ static void print_usage(int ret)
 	printf("\t-V|--version                print the mkfs.btrfs version and exit\n");
 	printf("\t--help                      print this help and exit\n");
 	printf("  deprecated:\n");
-	printf("\t-A|--alloc-start START      the offset to start the filesystem\n");
 	printf("\t-l|--leafsize SIZE          deprecated, alias for nodesize\n");
 	exit(ret);
 }
@@ -920,7 +919,6 @@ int BOX_MAIN(mkfs)(int argc, char **argv)
 	char *label = NULL;
 	u64 block_count = 0;
 	u64 dev_block_count = 0;
-	u64 alloc_start = 0;
 	u64 metadata_profile = 0;
 	u64 data_profile = 0;
 	u32 nodesize = max_t(u32, sysconf(_SC_PAGESIZE),
@@ -960,7 +958,6 @@ int BOX_MAIN(mkfs)(int argc, char **argv)
 		int c;
 		enum { GETOPT_VAL_SHRINK = 257, GETOPT_VAL_CHECKSUM };
 		static const struct option long_options[] = {
-			{ "alloc-start", required_argument, NULL, 'A'},
 			{ "byte-count", required_argument, NULL, 'b' },
 			{ "csum", required_argument, NULL,
 				GETOPT_VAL_CHECKSUM },
@@ -991,9 +988,6 @@ int BOX_MAIN(mkfs)(int argc, char **argv)
 		if (c < 0)
 			break;
 		switch(c) {
-			case 'A':
-				alloc_start = parse_size(optarg);
-				break;
 			case 'f':
 				force_overwrite = 1;
 				break;
@@ -1348,7 +1342,6 @@ int BOX_MAIN(mkfs)(int argc, char **argv)
 	close(fd);
 	fd = -1;
 	root = fs_info->fs_root;
-	fs_info->alloc_start = alloc_start;
 
 	ret = create_metadata_block_groups(root, mixed, &allocation);
 	if (ret) {

volumes.c

@@ -487,7 +487,7 @@ static int find_free_dev_extent_start(struct btrfs_device *device,
 	 * used by the boot loader (grub for example), so we make sure to start
 	 * at an offset of at least 1MB.
 	 */
-	min_search_start = max(root->fs_info->alloc_start, (u64)SZ_1M);
+	min_search_start = BTRFS_BLOCK_RESERVED_1M_FOR_SUPER;
 	search_start = max(search_start, min_search_start);
 
 	path = btrfs_alloc_path();
@@ -906,7 +906,7 @@ static u64 chunk_bytes_by_type(u64 type, u64 calc_size,
  * It is not equal to "device->total_bytes - device->bytes_used".
  * We do not allocate any chunk in 1M at beginning of device, and not
  * allowed to allocate any chunk before alloc_start if it is specified.
- * So search holes from max(1M, alloc_start) to device->total_bytes.
+ * So search holes from 1M to device->total_bytes.
  */
 static int btrfs_device_avail_bytes(struct btrfs_trans_handle *trans,
 				    struct btrfs_device *device,
@@ -917,21 +917,19 @@ static int btrfs_device_avail_bytes(struct btrfs_trans_handle *trans,
 	struct btrfs_key key;
 	struct btrfs_dev_extent *dev_extent = NULL;
 	struct extent_buffer *l;
-	u64 search_start = root->fs_info->alloc_start;
+	u64 search_start = BTRFS_BLOCK_RESERVED_1M_FOR_SUPER;;
 	u64 search_end = device->total_bytes;
 	u64 extent_end = 0;
 	u64 free_bytes = 0;
 	int ret;
 	int slot = 0;
 
-	search_start = max(BTRFS_BLOCK_RESERVED_1M_FOR_SUPER, search_start);
-
 	path = btrfs_alloc_path();
 	if (!path)
 		return -ENOMEM;
 
 	key.objectid = device->devid;
-	key.offset = root->fs_info->alloc_start;
+	key.offset = search_start;
 	key.type = BTRFS_DEV_EXTENT_KEY;
 
 	path->reada = READA_FORWARD;