btrfs: shrink the size of struct btrfs_delayed_item
Currently struct btrfs_delayed_item has a base size of 96 bytes, but its size can be decreased by doing the following 2 tweaks: 1) Change data_len from u32 to u16. Our maximum possible leaf size is 64K, so the data_len can never be larger than that, and in fact it is always much smaller than that. The max length for a dentry's name is ensured at the VFS level (PATH_MAX, 4096 bytes) and in struct btrfs_inode_ref and btrfs_dir_item we use a u16 to store the name's length; 2) Change 'ins_or_del' to a 1 bit enum, which is all we need since it can only have 2 values. After this there's also no longer the need to BUG_ON() before using 'ins_or_del' in several places. Also rename the field from 'ins_or_del' to 'type', which is more clear. These two tweaks decrease the size of struct btrfs_delayed_item from 96 bytes down to 88 bytes. A previous patch already reduced the size of this structure by 16 bytes, but an upcoming change will increase its size by 16 bytes (adding a struct list_head element). Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
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