On Tue, Apr 22, 2025 at 12:27:39PM +0000, John Garry wrote: > From: "Darrick J. Wong" <djwong@xxxxxxxxxx> > > Introduce a mount option to allow sysadmins to specify the maximum size > of an atomic write. If the filesystem can work with the supplied value, > that becomes the new guaranteed maximum. > > The value mustn't be too big for the existing filesystem geometry (max > write size, max AG/rtgroup size). We dynamically recompute the > tr_atomic_write transaction reservation based on the given block size, > check that the current log size isn't less than the new minimum log size > constraints, and set a new maximum. > > The actual software atomic write max is still computed based off of > tr_atomic_ioend the same way it has for the past few commits. The cap is a good idea, but a mount option for something that has strong effects for persistent application formats is a little suboptimal. But adding a sb field and an incompat bit wouldn't be great either. Maybe this another use case for a trusted xattr on the root inode like the autofsck flag?
