[BUG]
Since btrfs-progs v5.14, mkfs.btrfs no longer cleans up the temporary
SINGLE metadata chunks if "-R free-space-tree" is specified:
$ mkfs.btrfs -f -R free-space-tree -m dup -d dup /dev/test/test
$ btrfs ins dump-tree -t chunk /dev/test/test | grep "type METADATA"
length 8388608 owner 2 stripe_len 65536 type METADATA
length 268435456 owner 2 stripe_len 65536 type METADATA|DUP
[CAUSE]
Since commit 4b6cf2a3eb ("btrfs-progs: mkfs: generate free space tree
at make_btrfs() time"), free space tree is created when the temporary
btrfs image is created.
This behavior itself has no problem at all. The problem happens when
"-m DUP -d DUP" (or other profiles) is specified.
This makes btrfs to create extra chunks, enlarging free space tree so
that it can be as high as level 1.
During mkfs, we rely on recow_roots() to re-COW all tree blocks to the
newly allocated chunks.
But __recow_root() can only handle tree root at level 0, as it forces
root node to be COWed, not bothering the children leaves/nodes.
This makes part of the free space cache tree still live on the old
temporary chunks, leaving later cleanup_temp_chunks() unable to delete
temporary SINGLE chunks.
[FIX]
Rework __recow_root() to do a proper COW of the whole tree.
But above rework is not enough, as if a free space tree block is
allocated during current transaction, but before new chunks added.
Then the reworked __recow_root() can't COW it, as btrfs_search_slot()
won't COW a tree block allocated in current transaction.
So this patch will also commit current transaction before calling
recow_roots(), to force us to re-cow all tree blocks.
This shouldn't be a problem, as at the time of calling, we should have
less than a dozen tree blocks, thus there won't be a performance impact.
Reported-by: FireFish5000 <firefish5000@gmail.com>
Fixes: 4b6cf2a3eb ("btrfs-progs: mkfs: generate free space tree at make_btrfs() time")
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
0befc6dce2