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btrfs-progs: mkfs: Prevent temporary system chunk to use space in reserved 1M range 

When creating btrfs, mkfs.btrfs will firstly create a temporary system
chunk as basis, and then created needed trees or new devices.

However the layout temporary system chunk is hard-coded and uses
reserved [0, 1M) range of devid 1.

Change the temporary chunk layout from old:

0	1M				4M	5M
|<----------- temp chunk -------------->|
  And it's 1:1 mapped, which means it's a SINGLE chunk,
  and stripe offset is also 0.

to new layout:

0	1M				4M	5M
	|<----------- temp chunk -------------->|
  And still keeps the 1:1 mapping.

However this also affects btrfs_min_dev_size() which still assume
temporary chunks starts at device offset 0.

The problem can only be exposed by "-m single" or "-M" where we reuse the
temporary chunk.

With other meta profiles, system and meta chunks are allocated by later
btrfs_alloc_chunk() call, and old SINGLE chunks are removed, so it will
be no such problem for other meta profiles.

Reported-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Tested-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
[ folded fix for the minimal device size calculation ]
Signed-off-by: David Sterba <dsterba@suse.com>
master
Qu Wenruo 2018-01-10 12:56:47 +08:00 committed by David Sterba
parent de802a47e0
commit 997f9977c2
2 changed files with 33 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

34
mkfs/common.c
View File

@ -100,6 +100,21 @@ static int btrfs_create_tree_root(int fd, struct btrfs_mkfs_config *cfg,
*
* The superblock signature is not valid, denotes a partially created
* filesystem, needs to be finalized.
*
* The temporary fs will have the following chunk layout:
* Device extent:
* 0 1M 5M ......
* | Reserved | dev extent for SYS chunk |
*
* And chunk mapping will be:
* Chunk mapping:
* 0 1M 5M
* | | System chunk, 1:1 mapped |
*
* That's to say, there will only be *ONE* system chunk, mapped to
* [1M, 5M) physical offset.
* And the only chunk is also in logical address [1M, 5M), containing
* all essential tree blocks.
*/
int make_btrfs(int fd, struct btrfs_mkfs_config *cfg)
{
@ -154,8 +169,8 @@ int make_btrfs(int fd, struct btrfs_mkfs_config *cfg)
cfg->blocks[MKFS_SUPER_BLOCK] = BTRFS_SUPER_INFO_OFFSET;
for (i = 1; i < MKFS_BLOCK_COUNT; i++) {
cfg->blocks[i] = BTRFS_SUPER_INFO_OFFSET + SZ_1M +
cfg->nodesize * i;
cfg->blocks[i] = BTRFS_BLOCK_RESERVED_1M_FOR_SUPER +
cfg->nodesize * (i - 1);
}
btrfs_set_super_bytenr(&super, cfg->blocks[MKFS_SUPER_BLOCK]);
@ -309,7 +324,7 @@ int make_btrfs(int fd, struct btrfs_mkfs_config *cfg)
/* then we have chunk 0 */
btrfs_set_disk_key_objectid(&disk_key, BTRFS_FIRST_CHUNK_TREE_OBJECTID);
btrfs_set_disk_key_offset(&disk_key, 0);
btrfs_set_disk_key_offset(&disk_key, BTRFS_BLOCK_RESERVED_1M_FOR_SUPER);
btrfs_set_disk_key_type(&disk_key, BTRFS_CHUNK_ITEM_KEY);
btrfs_set_item_key(buf, &disk_key, nritems);
btrfs_set_item_offset(buf, btrfs_item_nr(nritems), itemoff);
@ -325,7 +340,8 @@ int make_btrfs(int fd, struct btrfs_mkfs_config *cfg)
btrfs_set_chunk_sector_size(buf, chunk, cfg->sectorsize);
btrfs_set_chunk_num_stripes(buf, chunk, 1);
btrfs_set_stripe_devid_nr(buf, chunk, 0, 1);
btrfs_set_stripe_offset_nr(buf, chunk, 0, 0);
btrfs_set_stripe_offset_nr(buf, chunk, 0,
BTRFS_BLOCK_RESERVED_1M_FOR_SUPER);
nritems++;
write_extent_buffer(buf, super.dev_item.uuid,
@ -363,7 +379,7 @@ int make_btrfs(int fd, struct btrfs_mkfs_config *cfg)
sizeof(struct btrfs_dev_extent);
btrfs_set_disk_key_objectid(&disk_key, 1);
btrfs_set_disk_key_offset(&disk_key, 0);
btrfs_set_disk_key_offset(&disk_key, BTRFS_BLOCK_RESERVED_1M_FOR_SUPER);
btrfs_set_disk_key_type(&disk_key, BTRFS_DEV_EXTENT_KEY);
btrfs_set_item_key(buf, &disk_key, nritems);
btrfs_set_item_offset(buf, btrfs_item_nr(nritems), itemoff);
@ -374,7 +390,8 @@ int make_btrfs(int fd, struct btrfs_mkfs_config *cfg)
BTRFS_CHUNK_TREE_OBJECTID);
btrfs_set_dev_extent_chunk_objectid(buf, dev_extent,
BTRFS_FIRST_CHUNK_TREE_OBJECTID);
btrfs_set_dev_extent_chunk_offset(buf, dev_extent, 0);
btrfs_set_dev_extent_chunk_offset(buf, dev_extent,
BTRFS_BLOCK_RESERVED_1M_FOR_SUPER);
write_extent_buffer(buf, chunk_tree_uuid,
(unsigned long)btrfs_dev_extent_chunk_tree_uuid(dev_extent),
@ -466,6 +483,8 @@ u64 btrfs_min_dev_size(u32 nodesize, int mixed, u64 meta_profile,
/*
* Minimal size calculation is complex due to several factors:
* 0) Reserved 1M range.
*
* 1) Temporary chunk reuse
* If specified chunk profile is SINGLE, we can reuse
* temporary chunks, no need to allocate new chunks.
@ -484,7 +503,8 @@ u64 btrfs_min_dev_size(u32 nodesize, int mixed, u64 meta_profile,
* The latter two are all 8M, accroding to @calc_size of
* btrfs_alloc_chunk().
*/
reserved += BTRFS_MKFS_SYSTEM_GROUP_SIZE + SZ_8M * 2;
reserved += BTRFS_BLOCK_RESERVED_1M_FOR_SUPER +
BTRFS_MKFS_SYSTEM_GROUP_SIZE + SZ_8M * 2;
/*
* For real chunks, we need to select different sizes:

7
mkfs/main.c
View File

@ -66,10 +66,15 @@ static int create_metadata_block_groups(struct btrfs_root *root, int mixed,
bytes_used = btrfs_super_bytes_used(fs_info->super_copy);
root->fs_info->system_allocs = 1;
/*
* First temporary system chunk must match the chunk layout
* created in make_btrfs().
*/
ret = btrfs_make_block_group(trans, fs_info, bytes_used,
BTRFS_BLOCK_GROUP_SYSTEM,
BTRFS_FIRST_CHUNK_TREE_OBJECTID,
0, BTRFS_MKFS_SYSTEM_GROUP_SIZE);
BTRFS_BLOCK_RESERVED_1M_FOR_SUPER,
BTRFS_MKFS_SYSTEM_GROUP_SIZE);
allocation->system += BTRFS_MKFS_SYSTEM_GROUP_SIZE;
if (ret)
return ret;