From: Jaegeuk Kim <jaegeuk@kernel.org>
Date: Wed, 10 Sep 2014 23:53:02 +0000 (-0700)
Subject: f2fs: give an option to enable in-place-updates during fsync to users
X-Git-Tag: fixes-for-v3.18-merge-window~8^2~28
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c1ce1b02bb25640567dc484dc94d3a195d21e705;p=pandora-kernel.git

f2fs: give an option to enable in-place-updates during fsync to users

If user wrote F2FS_IPU_FSYNC:4 in /sys/fs/f2fs/ipu_policy, f2fs_sync_file
only starts to try in-place-updates.
And, if the number of dirty pages is over /sys/fs/f2fs/min_fsync_blocks, it
keeps out-of-order manner. Otherwise, it triggers in-place-updates.

This may be used by storage showing very high random write performance.

For example, it can be used when,

Seq. writes (Data) + wait + Seq. writes (Node)

is pretty much slower than,

Rand. writes (Data)

Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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