On Wed, Apr 19, 2023 at 07:18:13PM +0300, Amir Goldstein wrote: > From: Brian Foster <bfoster@xxxxxxxxxx> > > commit 7cd3099f4925d7c15887d1940ebd65acd66100f5 upstream. > > Per-inode ioend completion batching has a log reservation deadlock > vector between preallocated append transactions and transactions > that are acquired at completion time for other purposes (i.e., > unwritten extent conversion or COW fork remaps). For example, if the > ioend completion workqueue task executes on a batch of ioends that > are sorted such that an append ioend sits at the tail, it's possible > for the outstanding append transaction reservation to block > allocation of transactions required to process preceding ioends in > the list. > > Append ioend completion is historically the common path for on-disk > inode size updates. While file extending writes may have completed > sometime earlier, the on-disk inode size is only updated after > successful writeback completion. These transactions are preallocated > serially from writeback context to mitigate concurrency and > associated log reservation pressure across completions processed by > multi-threaded workqueue tasks. > > However, now that delalloc blocks unconditionally map to unwritten > extents at physical block allocation time, size updates via append > ioends are relatively rare. This means that inode size updates most > commonly occur as part of the preexisting completion time > transaction to convert unwritten extents. As a result, there is no > longer a strong need to preallocate size update transactions. > > Remove the preallocation of inode size update transactions to avoid > the ioend completion processing log reservation deadlock. Instead, > continue to send all potential size extending ioends to workqueue > context for completion and allocate the transaction from that > context. This ensures that no outstanding log reservation is owned > by the ioend completion worker task when it begins to process > ioends. > > Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx> > Reviewed-by: Christoph Hellwig <hch@xxxxxx> > Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx> > Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx> > Reported-by: Christian Theune <ct@xxxxxxxxxxxxxxx> > Link: https://lore.kernel.org/linux-xfs/CAOQ4uxjj2UqA0h4Y31NbmpHksMhVrXfXjLG4Tnz3zq_UR-3gSA@xxxxxxxxxxxxxx/ > Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx> > Acked-by: Darrick J. Wong <djwong@xxxxxxxxxx> > --- > > Greg, > > One more fix from v5.13 that I missed from my backports. Now queued up, thanks. greg k-h
