From: Dave Chinner Date: Thu, 22 Mar 2012 05:15:11 +0000 (+0000) Subject: xfs: Account log unmount transaction correctly X-Git-Tag: v3.2.55~62 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1c7a9417edf13a32244bba86cf8197073ebad9a7;p=pandora-kernel.git xfs: Account log unmount transaction correctly commit 3948659e30808fbaa7673bbe89de2ae9769e20a7 upstream. There have been a few reports of this warning appearing recently: XFS (dm-4): xlog_space_left: head behind tail tail_cycle = 129, tail_bytes = 20163072 GH cycle = 129, GH bytes = 20162880 The common cause appears to be lots of freeze and unfreeze cycles, and the output from the warnings indicates that we are leaking around 8 bytes of log space per freeze/unfreeze cycle. When we freeze the filesystem, we write an unmount record and that uses xlog_write directly - a special type of transaction, effectively. What it doesn't do, however, is correctly account for the log space it uses. The unmount record writes an 8 byte structure with a special magic number into the log, and the space this consumes is not accounted for in the log ticket tracking the operation. Hence we leak 8 bytes every unmount record that is written. Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Signed-off-by: Ben Myers Signed-off-by: Ben Hutchings --- Reading git-diff-tree failed