svn commit: r187468 - head/sys/ufs/ffs

[Roman Divacky]

On Tue, Jan 20, 2009 at 11:30:22AM +0000, Konstantin Belousov wrote:
> Author: kib
> Date: Tue Jan 20 11:30:22 2009
> New Revision: 187468
> URL: http://svn.freebsd.org/changeset/base/187468
> 
> Log:
>   When extending inode size, we call vnode_pager_setsize(), to have a
>   address space where to put vnode pages, and then call UFS_BALLOC(),
>   to actually allocate new block and map it. When UFS_BALLOC() returns
>   error, sometimes we forget to revert the vm object size increase,
>   allowing for the pages that are not backed by the logical disk blocks.
>   
>   Revert vnode_pager_setsize() back when UFS_BALLOC() failed, for
>   ffs_truncate() and ffs_write().

can you describe in what scenario this can trigger? can it be that
many smallish (a few tens of kB?) of mmaped files being read/write
may cause this?

thnx