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    SubjectRe: [PATCH 6/8] xfs: Use generic writers counter instead of m_active_trans counter
    On 1/20/12 2:34 PM, Jan Kara wrote:
    > m_active_trans counter is racy wrt filesystem freezing. The patch replaces it
    > with generic counter of running transactions which is properly synchronized
    > with filesystem freezing. Things are a bit more complex because we need to log
    > a dummy transaction and free block counters after the filesystem is frozen so
    > we need to pass information to _xfs_trans_alloc() whether the transaction is
    > part of filesystem freezing or not.
    >
    > Signed-off-by: Jan Kara <jack@suse.cz>
    > ---

    ...

    > xfs_trans_t *
    > _xfs_trans_alloc(
    > xfs_mount_t *mp,
    > uint type,
    > - uint memflags)
    > + uint memflags,
    > + bool freezing)
    > {
    > xfs_trans_t *tp;
    >
    > - atomic_inc(&mp->m_active_trans);
    > -
    > + if (!freezing)
    > + sb_start_write(mp->m_super, SB_FREEZE_TRANS);
    > + else
    > + WARN_ON(xfs_test_for_freeze(mp) != SB_FREEZE_TRANS);

    Hm this could be an issue because for both the umount path and the
    freeze / xfs_quiesce_attr path, we call xfs_log_sbcount which sends
    "true" for freezing and we'll trip up here because we won't be
    in SB_FREEZE_TRANS during umount.

    I think we have to push the flag all the way up to xfs_log_sbcount
    callers?

    -Eric


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