Re: [PATCH]: VM 7/8 cluster pageout

[Nikita Danilov <nikita@clusterfs.com>]

Andrew Morton writes:
 > Nikita Danilov <nikita@clusterfs.com> wrote:
 > >
 > > Andrew Morton writes:
 > >  > Nikita Danilov <nikita@clusterfs.com> wrote:
 > >  > >
 > >  > > Implement pageout clustering at the VM level.
 > >  > 
 > >  > I dunno...
 > >  > 
 > >  > Once __mpage_writepages() has started I/O against the pivot page, I don't
 > >  > see that we have any guarantees that some other CPU cannot come in,
 > >  > truncated or reclaim all the inode's pages and then reclaimed the inode
 > >  > altogether.  While __mpage_writepages() is still dinking with it all.
 > > 
 > > Ah, silly me. Will __iget(page->mapping->host) in pageout_cluster() be
 > > enough? We risk truncate on matching iput(), but VM scanner calls iput()
 > > on inodes with ->i_nlink == 0 already (from shrink_dcache()).
 > 
 > I have vague memories about iput() in page reclaim causing deadlocks or
 > some other nastiness.  Maybe not.

Aren't you talking about

http://marc.theaimsgroup.com/?t=108272583200001&r=1&w=2

by any chance? As I remember it, conclusion was that file system has to
be ready to handle final iput() from within GFP_FS allocation.

 > 

Nikita.
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