On Wed, Apr 19, 2023 at 07:32:59AM +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> > --- > > Darrick, > > As I wrote in $LINK, this fix from v5.13 was missed from my backports > due to a tool error. > > It's also in good timeing because Chandan has just finished the v5.12 > backports. > > I ran it though 10 kdevops cycles. > > Please approve. Looks good to me, Acked-by: Darrick J. Wong <djwong@xxxxxxxxxx> --D > > Thanks, > Amir. > > fs/xfs/xfs_aops.c | 45 +++------------------------------------------ > 1 file changed, 3 insertions(+), 42 deletions(-) > > diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c > index 953de843d9c3..e341d6531e68 100644 > --- a/fs/xfs/xfs_aops.c > +++ b/fs/xfs/xfs_aops.c > @@ -39,33 +39,6 @@ static inline bool xfs_ioend_is_append(struct iomap_ioend *ioend) > XFS_I(ioend->io_inode)->i_d.di_size; > } > > -STATIC int > -xfs_setfilesize_trans_alloc( > - struct iomap_ioend *ioend) > -{ > - struct xfs_mount *mp = XFS_I(ioend->io_inode)->i_mount; > - struct xfs_trans *tp; > - int error; > - > - error = xfs_trans_alloc(mp, &M_RES(mp)->tr_fsyncts, 0, 0, 0, &tp); > - if (error) > - return error; > - > - ioend->io_private = tp; > - > - /* > - * We may pass freeze protection with a transaction. So tell lockdep > - * we released it. > - */ > - __sb_writers_release(ioend->io_inode->i_sb, SB_FREEZE_FS); > - /* > - * We hand off the transaction to the completion thread now, so > - * clear the flag here. > - */ > - xfs_trans_clear_context(tp); > - return 0; > -} > - > /* > * Update on-disk file size now that data has been written to disk. > */ > @@ -191,12 +164,10 @@ xfs_end_ioend( > error = xfs_reflink_end_cow(ip, offset, size); > else if (ioend->io_type == IOMAP_UNWRITTEN) > error = xfs_iomap_write_unwritten(ip, offset, size, false); > - else > - ASSERT(!xfs_ioend_is_append(ioend) || ioend->io_private); > > + if (!error && xfs_ioend_is_append(ioend)) > + error = xfs_setfilesize(ip, ioend->io_offset, ioend->io_size); > done: > - if (ioend->io_private) > - error = xfs_setfilesize_ioend(ioend, error); > iomap_finish_ioends(ioend, error); > memalloc_nofs_restore(nofs_flag); > } > @@ -246,7 +217,7 @@ xfs_end_io( > > static inline bool xfs_ioend_needs_workqueue(struct iomap_ioend *ioend) > { > - return ioend->io_private || > + return xfs_ioend_is_append(ioend) || > ioend->io_type == IOMAP_UNWRITTEN || > (ioend->io_flags & IOMAP_F_SHARED); > } > @@ -259,8 +230,6 @@ xfs_end_bio( > struct xfs_inode *ip = XFS_I(ioend->io_inode); > unsigned long flags; > > - ASSERT(xfs_ioend_needs_workqueue(ioend)); > - > spin_lock_irqsave(&ip->i_ioend_lock, flags); > if (list_empty(&ip->i_ioend_list)) > WARN_ON_ONCE(!queue_work(ip->i_mount->m_unwritten_workqueue, > @@ -510,14 +479,6 @@ xfs_prepare_ioend( > ioend->io_offset, ioend->io_size); > } > > - /* Reserve log space if we might write beyond the on-disk inode size. */ > - if (!status && > - ((ioend->io_flags & IOMAP_F_SHARED) || > - ioend->io_type != IOMAP_UNWRITTEN) && > - xfs_ioend_is_append(ioend) && > - !ioend->io_private) > - status = xfs_setfilesize_trans_alloc(ioend); > - > memalloc_nofs_restore(nofs_flag); > > if (xfs_ioend_needs_workqueue(ioend)) > -- > 2.34.1 >
