will remove indirect function calls using nilfs_btree_operations
table.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

Previously, the bmap codes of nilfs used three types of function
tables.  The abuse of indirect function calls decreased source
readability and suffered many indirect jumps which would confuse
branch prediction of processors.

This eliminates one type of the function tables,
nilfs_bmap_ptr_operations, which was used to dispatch low level
pointer operations of the nilfs bmap.

This adds a new integer variable "b_ptr_type" to nilfs_bmap struct,
and uses the value to select the pointer operations.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

This will cut off 16 bytes from the nilfs_bmap struct which is
embedded in the on-memory inode of nilfs.

The b_high field was never used, and the b_low field stores a constant
value which can be determined by whether the inode uses btree for
block mapping or not.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

This indirect function is set to NULL only for gc cache inodes, but
the gc cache inodes never call this function.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

Two get block function for btree nodes, nilfs_bmap_get_block() and
nilfs_bmap_get_new_block(), are called only from the btree codes.
This relocation will increase opportunities of compiler optimization.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs_bmap_delete_block() is a wrapper function calling
nilfs_btnode_delete().  This removes it for simplicity.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs_bmap_put_block() is a wrapper function calling brelse().  This
eliminates the wrapper for simplicity.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

This simplifies some low level functions of bmap.

Three bmap pointer operations, nilfs_bmap_start_v(),
nilfs_bmap_commit_v(), and nilfs_bmap_abort_v(), are unified into one
nilfs_bmap_start_v() function. And the related indirect function calls
are replaced with it.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

Pekka Enberg advised me:
> It would be nice if BUG(), BUG_ON(), and panic() calls would be
> converted to proper error handling using WARN_ON() calls. The BUG()
> call in nilfs_cpfile_delete_checkpoints(), for example, looks to be
> triggerable from user-space via the ioctl() system call.

This will follow the comment and keep them to a minimum.
Acked-by: NPekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This cleans up the strange indirect function calling convention used in
nilfs to follow the normal kernel coding style.
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>
Acked-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This adds declarations and functions of NILFS2 B-tree.

Two variants are integrated in the NILFS2 B-tree.  The B-tree for the most
files points to the child nodes or data blocks with virtual block
addresses, whereas the B-tree of the DAT uses actual block addresses.
Signed-off-by: NKoji Sato <sato.koji@lab.ntt.co.jp>
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>