Re: [dm-devel] [PATCH] deadlock with suspend and quotas

[Mikulas Patocka]

> > dm-ioctl.h:
> > /*
> >  * Set this to avoid attempting to freeze any filesystem when suspending.
> >  */
> > #define DM_SKIP_LOCKFS_FLAG     (1 << 10) /* In */
>   Thanks. I was now checking in detail and indeed FIFREEZE fails if
> ->freeze_fs is not set. And only xfs, ext3, ext4, reiserfs, jfs, nilfs2,
> and gfs2 provide this function. So I was correct in assuming that when
> filesystem supports FIFREEZE it must make sure no modifications happen to
> the filesystem. So I believe that my original plan for sync to skip frozen
> filesystem is correct.
> 
> 								Honza

LVM doesn't suspend with FIFREEZE, it calls freeze_bdev directly from 
drivers/md/dm.c (and it works for all filesystems, including ext2). So if 
you skip sync of frozen filesystems, you introduce a data corruption if 
someone takes a snapshot of ext2.

Mikulas
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