btrfs: increase ->free_chunk_space in btrfs_grow_device

My overcommit patch exposed a bug with btrfs/177 [1].  The problem here is
that when we grow the device we're not adding to ->free_chunk_space, so
subsequent allocations can cause ->free_chunk_space to wrap, which
causes problems in can_overcommit because we add this to ->total_bytes,
which causes the counter to wrap and gives us an unexpected ENOSPC.

Fix this by properly updating ->free_chunk_space with the new available
space in btrfs_grow_device.

[1] First version of the fix:
    https://lore.kernel.org/linux-btrfs/b97e47ce0ce1d41d221878de7d6090b90aa7a597.1695065233.git.josef@toxicpanda.com/

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 8355533fd2876c6f7e4ca2c36349510ac18d852f..790368d4b866bacaccced70fcbe84cda98c3ff82 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2812,6 +2812,7 @@ int btrfs_grow_device(struct btrfs_trans_handle *trans,
        btrfs_set_super_total_bytes(super_copy,
                        round_down(old_total + diff, fs_info->sectorsize));
        device->fs_devices->total_rw_bytes += diff;
+       atomic64_add(diff, &fs_info->free_chunk_space);
 
        btrfs_device_set_total_bytes(device, new_size);
        btrfs_device_set_disk_total_bytes(device, new_size);