On Thu, May 27, 2021 at 01:38:44PM -0700, Darrick J. Wong wrote: > On Wed, May 19, 2021 at 10:13:17PM +1000, Dave Chinner wrote: > > +As a result, permanent transactions only "regrant" reservation space during > > +xfs_trans_commit() calls, while the physical log space reservation - tracked by > > +the write head - is then reserved separately by a call to xfs_log_reserve() > > +after the commit completes. Once the commit completes, we can sleep waiting for > > +physical log space to be reserved from the write grant head, but only if one > > +critical rule has been observed:: > > + > > + Code using permanent reservations must always log the items they hold > > + locked across each transaction they roll in the chain. > > + > > +"Re-logging" the locked items on every transaction roll ensures that the items > > +the transaction chain is rolling are always relocated to the physical head of > > This reads (to me) a little awkwardly. One could ask if the transaction > chain itself is rolling the items? Which is not really what's > happening. How about: > > "...ensures that the items attached to the transaction chain being > rolled are always relocated..." Fixed. > > -This relogging is also used to implement long-running, multiple-commit > > -transactions. These transaction are known as rolling transactions, and require > > -a special log reservation known as a permanent transaction reservation. A > > -typical example of a rolling transaction is the removal of extents from an > > +A typical example of a rolling transaction is the removal of extents from an > > inode which can only be done at a rate of two extents per transaction because > > Ignoring rt files, do we even have /that/ limit anymore? Especially > considering the other patchset you just sent... :) Well.... Remind me to make this update in that patch set if I forget to do it. :P > With that one odd sentence up there reworked, > Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx> Thx! -Dave. -- Dave Chinner david@xxxxxxxxxxxxx
