On Fri, Jan 16, 2009 at 7:24 AM, Yuri Tikhonov <yur@xxxxxxxxxxx> wrote: >> Ok, I now see why this change was made. Please make this changelog >> more descriptive than "Rewrite handle_stripe_dirtying6 function to >> work asynchronously." > > Sure, how about the following: > > " > > md: rewrite handle_stripe_dirtying6 in asynchronous way > > Processing stripe dirtying in asynchronous way requires some changes > to the handle_stripe_dirtying6() algorithm. > > In the synchronous implementation of the stripe dirtying we processed > dirtying of a degraded stripe (with partially changed strip(s) located > on the failed drive(s)) inside one handle_stripe_dirtying6() call: > - we computed the missed strips from the old parities, and thus got > the fully up-to-date stripe, then > - we did reconstruction using the new data to write. > > In the asynchronous case of handle_stripe_dirtying6() we don't > process anything right inside this function (since we under the lock), > but only schedule the necessary operations with flags. Thus, if > handle_stripe_dirtying6() is performed on the top of a degraded array > we should schedule the reconstruction operation when the failed strips > are marked (by previously called fetch_block6()) as to be computed > (with the R5_Wantcompute flag), and all the other strips of the stripe > are UPTODATE. The schedule_reconstruction() function will set the > STRIPE_OP_POSTXOR flag [for new parity calculation], which is then > handled in raid_run_ops() after the STRIPE_OP_COMPUTE_BLK one [which > causes computing of the data missed]. > > " Excellent! Thanks, Dan -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
