Messages in this thread | | | Date | Fri, 11 Mar 2011 19:40:30 -0500 | From | Ric Wheeler <> | Subject | Re: [PATCH v3] introduce sys_syncfs to sync a single file system |
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On 03/11/2011 06:45 PM, Indan Zupancic wrote: > On Fri, March 11, 2011 12:55, Arnd Bergmann wrote: >> On Friday 11 March 2011, Indan Zupancic wrote: >>>> http://marc.info/?l=linux-fsdevel&m=127970513829285&w=2 >>> The patch there seems much more reasonable than introducing a whole >>> new systemcall just for 20 lines of kernel code. New system calls are >>> added too easily nowadays. >> The only problem with adding new system calls is that we are stuck >> with the interface until the end of time, so we must be sure not >> to get it wrong. The same thing is true for any other interface >> such as ioctl or extensions to existing system calls. People usually >> get away with adding new ioctls more easily because it is less >> obvious when they are added. > Agreed. > > I'm not sure this feature is important enough to add. I can't really > think of a regular use case where this would be useful, generally > it's transparent on which mount files are. Add symlinks, and you > give users a lot of rope. Any user has to make sure that all the > files they want to sync are on the same file system. > > About the arguments against sync(2): > >> - On machines with many mounts, it is not at all uncommon for some of >> them to hang (e.g. unresponsive NFS server). sync(2) will get stuck on >> those and may never get to the one you do care about (e.g., /). > It would be better to fix NFS, or mount it with the fsc option (assuming > a sync will write to the local cache instead of hanging forever then). > >> - Some applications write lots of data to the file system and then >> want to make sure it is flushed to disk. Calling fsync(2) on each >> file introduces unnecessary ordering constraints that result in a large >> amount of sub-optimal writeback/flush/commit behavior by the file >> system. > You can use sync_file_range() on those files to schedule the writes > and then do the fsync(2) as usual (both on files and dirs). > > If there still is a good reason to implement this, please don't add it > as a new system call, but add it to sync_file_range(), as that seems > the best place for odd file synchronisation operations. > > Greetings, > > Indan > > > --
Hi Indan,
I think that you missed the point of the extension.
Ric
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