git: sys/vfs/hammer: Add HAMMER_MIN_UNDO_BIGBLOCKS to set minimum undo fifo to 512MB

[Tomohiro Kusumi]

commit 668f11d85250ff62937eaca5f0219b55182a6c1d
Author: Tomohiro Kusumi <kusumi.tomohiro at gmail.com>
Date:   Sat Oct 29 16:03:13 2016 +0900

    sys/vfs/hammer: Add HAMMER_MIN_UNDO_BIGBLOCKS to set minimum undo fifo to 512MB
    
    Add HAMMER_MIN_UNDO_BIGBLOCKS which is 64 big-blocks in addition
    to HAMMER_MAX_UNDO_BIGBLOCKS which is 128 big-blocks.
    
    This not only removes magic number 500*1024*1024 from source,
    but also changes minimum undo fifo from 500MB to 512MB in terms
    of userspace command.
    
    This means the number of big-blocks created by newfs_hammer by
    default (depending on volumes size), and the minumum number of
    big-blocks that can be specified, change from 63(504MB) to 64(512MB),
    which is trivial given the size of total volumes required by
    the filesystem.
    
    I think it's just better to keep the number multiple of 8MB.
    As mentioned, one can't assign exact 500MB for undo fifo anyway
    as it gets aligned to big-block boundary.
    
    This change doesn't affect the existing filesystem.

Summary of changes:
 sbin/hammer/ondisk.c             |  6 +++---
 sbin/newfs_hammer/newfs_hammer.8 |  6 +++---
 sbin/newfs_hammer/newfs_hammer.c | 28 ++++++++++++++++++----------
 sys/vfs/hammer/hammer_disk.h     |  6 ++++--
 4 files changed, 28 insertions(+), 18 deletions(-)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/668f11d85250ff62937eaca5f0219b55182a6c1d


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