Messages in this thread | | | Date | Wed, 26 Jan 2011 06:49:24 -0500 | From | Ric Wheeler <> | Subject | Re: [PATCHSET] Refactor barrier=/nobarrier flags from fs to block layer |
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On 01/26/2011 02:12 AM, Darrick J. Wong wrote: > Hello, > > From what I can tell, most of the filesystems that know how to issue commands > to flush the write cache also have some mechanism for the user to override > whether or not the filesystem actually issues those flushes. Unfortunately, > the term "barrier" is obsolete having been changed into flushes in 2.6.36, and > many of the filesystems implement the mount options with slightly different > syntaxes (barrier=[0|1|none|flush], nobarrier, etc). > > This patchset adds to the block layer a sysfs knob that an administrator can > use to disable flushes, and removes the mount options from the filesystem code. > As a starting point, I'm removing the mount options and flush toggle from > jbd2/ext4. > > Anyway, I'm looking for some feedback about refactoring the barrier/flush > control knob into the block layer. It sounds like we want a knob that picks > the safest option (issue flushes when supported) unless the administrator > decides that it is appropriate to do otherwise. I suspect that there are good > arguments for not having a knob at all, and good arguments for a safe knob. > However, since I don't see the barrier options being removed en masse, I'm > assuming that we still want a knob somewhere. Do we need the ignore_fua knob > too? Is this the proper way to deprecate mount options out of filesystems? > > --D
Just to be clear, I strongly object to remove the mount options.
"Barrier" and "poke a control knob in the block" layer are both equally mysterious and meaningless to real users, so I do not see this as a gain,
Ric
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