The subject should have been [PATCH 00/27]... Sorry for the mistake.
Honza
On Mon 16-04-12 18:13:38, Jan Kara wrote:
> Hello,
>
> here is the fifth iteration of my patches to improve filesystem freezing.
> No serious changes since last time. Mostly I rebased patches and merged this
> series with series moving file_update_time() to ->page_mkwrite() to simplify
> testing and merging.
>
> Filesystem freezing is currently racy and thus we can end up with dirty data
> on
> frozen filesystem (see changelog patch 13 for detailed race description). This
> patch series aims at fixing this.
>
> To be able to block all places where inodes get dirtied, I've moved filesystem
> file_update_time() call to ->page_mkwrite callback (patches 01-07) and put
> freeze handling in mnt_want_write() / mnt_drop_write(). That however required
> some code shuffling and changes to kern_path_create() (see patches 09-12). I
> think the result is OK but opinions may differ ;). The advantage of this
> change
> also is that all filesystems get freeze protection almost for free - even ext2
> can handle freezing well now.
>
> Another potential contention point might be patch 19. In that patch we make
> freeze_super() refuse to freeze the filesystem when there are open but
> unlinked
> files which may be impractical in some cases. The main reason for this is the
> problem with handling of file deletion from fput() called with mmap_sem held
> (e.g. from munmap(2)), and then there's the fact that we cannot really force
> such filesystem into a consistent state... But if people think that freezing
> with open but unlinked files should happen, then I have some possible
> solutions in mind (maybe as a separate patchset since this is large enough).
>
> I'm not able to hit any deadlocks, lockdep warnings, or dirty data on frozen
> filesystem despite beating it with fsstress and bash-shared-mapping while
> freezing and unfreezing for several hours (using ext4 and xfs) so I'm
> reasonably confident this could finally be the right solution.
>
> Changes since v4:
> * added a couple of Acked-by's
> * added some comments & doc update
> * added patches from series "Push file_update_time() into .page_mkwrite"
> since it doesn't make much sense to keep them separate anymore
> * rebased on top of 3.4-rc2
>
> Changes since v3:
> * added third level of freezing for fs internal purposes - hooked some
> filesystems to use it (XFS, nilfs2)
> * removed racy i_size check from filemap_mkwrite()
>
> Changes since v2:
> * completely rewritten
> * freezing is now blocked at VFS entry points
> * two stage freezing to handle both mmapped writes and other IO
>
> The biggest changes since v1:
> * have two counters to provide safe state transitions for SB_FREEZE_WRITE
> and SB_FREEZE_TRANS states
> * use percpu counters instead of own percpu structure
> * added documentation fixes from the old fs freezing series
> * converted XFS to use SB_FREEZE_TRANS counter instead of its private
> m_active_trans counter
>
> Honza
>
> CC: Alex Elder <[email protected]>
> CC: Anton Altaparmakov <[email protected]>
> CC: Ben Myers <[email protected]>
> CC: Chris Mason <[email protected]>
> CC: [email protected]
> CC: "David S. Miller" <[email protected]>
> CC: [email protected]
> CC: "J. Bruce Fields" <[email protected]>
> CC: Joel Becker <[email protected]>
> CC: KONISHI Ryusuke <[email protected]>
> CC: [email protected]
> CC: [email protected]
> CC: [email protected]
> CC: [email protected]
> CC: [email protected]
> CC: Mark Fasheh <[email protected]>
> CC: Miklos Szeredi <[email protected]>
> CC: [email protected]
> CC: OGAWA Hirofumi <[email protected]>
> CC: Steven Whitehouse <[email protected]>
> CC: "Theodore Ts'o" <[email protected]>
> CC: [email protected]
--
Jan Kara <[email protected]>
SUSE Labs, CR
