| Message ID | 20201208122824.16118-5-laoar.shao@gmail.com (mailing list archive) |
|---|---|
| State | Superseded, archived |
| Headers | show |
| Series | xfs: avoid transaction reservation recursion | expand |
On Tue, Dec 08, 2020 at 08:28:24PM +0800, Yafang Shao wrote: > PF_FSTRANS which is used to avoid transaction reservation recursion, is > dropped since commit 9070733b4efa ("xfs: abstract PF_FSTRANS to > PF_MEMALLOC_NOFS") and commit 7dea19f9ee63 ("mm: introduce > memalloc_nofs_{save,restore} API") and replaced by PF_MEMALLOC_NOFS which > means to avoid filesystem reclaim recursion. > > As these two flags have different meanings, we'd better reintroduce > PF_FSTRANS back. To avoid wasting the space of PF_* flags in task_struct, > we can reuse the current->journal_info to do that, per Willy. As the > check of transaction reservation recursion is used by XFS only, we can > move the check into xfs_vm_writepage(s), per Dave. > > To better abstract that behavoir, two new helpers are introduced, as > follows, > - xfs_trans_context_active > To check whehter current is in fs transcation or not > - xfs_trans_context_swap > Transfer the transaction context when rolling a permanent transaction > > These two new helpers are instroduced in xfs_trans.h. > > Cc: Darrick J. Wong <darrick.wong@oracle.com> > Cc: Matthew Wilcox (Oracle) <willy@infradead.org> > Cc: Christoph Hellwig <hch@lst.de> > Cc: Dave Chinner <david@fromorbit.com> > Cc: Michal Hocko <mhocko@kernel.org> > Cc: David Howells <dhowells@redhat.com> > Cc: Jeff Layton <jlayton@redhat.com> > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > --- > fs/iomap/buffered-io.c | 7 ------- > fs/xfs/xfs_aops.c | 17 +++++++++++++++++ > fs/xfs/xfs_trans.c | 3 +++ > fs/xfs/xfs_trans.h | 22 ++++++++++++++++++++++ > 4 files changed, 42 insertions(+), 7 deletions(-) > > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c > index 10cc7979ce38..3c53fa6ce64d 100644 > --- a/fs/iomap/buffered-io.c > +++ b/fs/iomap/buffered-io.c > @@ -1458,13 +1458,6 @@ iomap_do_writepage(struct page *page, struct writeback_control *wbc, void *data) > PF_MEMALLOC)) > goto redirty; > > - /* > - * Given that we do not allow direct reclaim to call us, we should > - * never be called in a recursive filesystem reclaim context. > - */ > - if (WARN_ON_ONCE(current->flags & PF_MEMALLOC_NOFS)) > - goto redirty; > - > /* > * Is this page beyond the end of the file? > * > diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c > index 2371187b7615..0da0242d42c3 100644 > --- a/fs/xfs/xfs_aops.c > +++ b/fs/xfs/xfs_aops.c > @@ -568,6 +568,16 @@ xfs_vm_writepage( > { > struct xfs_writepage_ctx wpc = { }; > > + /* > + * Given that we do not allow direct reclaim to call us, we should > + * never be called while in a filesystem transaction. > + */ > + if (WARN_ON_ONCE(xfs_trans_context_active())) { > + redirty_page_for_writepage(wbc, page); > + unlock_page(page); > + return 0; > + } > + > return iomap_writepage(page, wbc, &wpc.ctx, &xfs_writeback_ops); > } > > @@ -579,6 +589,13 @@ xfs_vm_writepages( > struct xfs_writepage_ctx wpc = { }; > > xfs_iflags_clear(XFS_I(mapping->host), XFS_ITRUNCATED); > + /* > + * Given that we do not allow direct reclaim to call us, we should > + * never be called while in a filesystem transaction. > + */ > + if (WARN_ON_ONCE(xfs_trans_context_active())) > + return 0; > + > return iomap_writepages(mapping, wbc, &wpc.ctx, &xfs_writeback_ops); > } > > diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c > index fe20398a214e..08d4916ffb13 100644 > --- a/fs/xfs/xfs_trans.c > +++ b/fs/xfs/xfs_trans.c > @@ -124,6 +124,9 @@ xfs_trans_dup( > tp->t_rtx_res = tp->t_rtx_res_used; > ntp->t_pflags = tp->t_pflags; This one line (ntp->t_pflags = tp->t_pflags) should move to xfs_trans_context_swap. --D > > + /* Associate the new transaction with this thread. */ > + xfs_trans_context_swap(tp, ntp); > + > /* move deferred ops over to the new tp */ > xfs_defer_move(ntp, tp); > > diff --git a/fs/xfs/xfs_trans.h b/fs/xfs/xfs_trans.h > index 44b11c64a15e..d596a375e3bf 100644 > --- a/fs/xfs/xfs_trans.h > +++ b/fs/xfs/xfs_trans.h > @@ -268,16 +268,38 @@ xfs_trans_item_relog( > return lip->li_ops->iop_relog(lip, tp); > } > > +static inline bool > +xfs_trans_context_active(void) > +{ > + /* Use journal_info to indicate current is in a transaction */ > + return current->journal_info != NULL; > +} > + > static inline void > xfs_trans_context_set(struct xfs_trans *tp) > { > + ASSERT(!current->journal_info); > + current->journal_info = tp; > tp->t_pflags = memalloc_nofs_save(); > } > > static inline void > xfs_trans_context_clear(struct xfs_trans *tp) > { > + ASSERT(current->journal_info == tp); > + current->journal_info = NULL; > memalloc_nofs_restore(tp->t_pflags); > } > > +/* > + * Transfer the transaction context when rolling a permanent > + * transaction. > + */ > +static inline void > +xfs_trans_context_swap(struct xfs_trans *tp, struct xfs_trans *ntp) > +{ > + ASSERT(current->journal_info == tp); > + current->journal_info = ntp; > +} > + > #endif /* __XFS_TRANS_H__ */ > -- > 2.18.4 >
On Wed, Dec 9, 2020 at 3:00 AM Darrick J. Wong <darrick.wong@oracle.com> wrote: > > On Tue, Dec 08, 2020 at 08:28:24PM +0800, Yafang Shao wrote: > > PF_FSTRANS which is used to avoid transaction reservation recursion, is > > dropped since commit 9070733b4efa ("xfs: abstract PF_FSTRANS to > > PF_MEMALLOC_NOFS") and commit 7dea19f9ee63 ("mm: introduce > > memalloc_nofs_{save,restore} API") and replaced by PF_MEMALLOC_NOFS which > > means to avoid filesystem reclaim recursion. > > > > As these two flags have different meanings, we'd better reintroduce > > PF_FSTRANS back. To avoid wasting the space of PF_* flags in task_struct, > > we can reuse the current->journal_info to do that, per Willy. As the > > check of transaction reservation recursion is used by XFS only, we can > > move the check into xfs_vm_writepage(s), per Dave. > > > > To better abstract that behavoir, two new helpers are introduced, as > > follows, > > - xfs_trans_context_active > > To check whehter current is in fs transcation or not > > - xfs_trans_context_swap > > Transfer the transaction context when rolling a permanent transaction > > > > These two new helpers are instroduced in xfs_trans.h. > > > > Cc: Darrick J. Wong <darrick.wong@oracle.com> > > Cc: Matthew Wilcox (Oracle) <willy@infradead.org> > > Cc: Christoph Hellwig <hch@lst.de> > > Cc: Dave Chinner <david@fromorbit.com> > > Cc: Michal Hocko <mhocko@kernel.org> > > Cc: David Howells <dhowells@redhat.com> > > Cc: Jeff Layton <jlayton@redhat.com> > > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > > --- > > fs/iomap/buffered-io.c | 7 ------- > > fs/xfs/xfs_aops.c | 17 +++++++++++++++++ > > fs/xfs/xfs_trans.c | 3 +++ > > fs/xfs/xfs_trans.h | 22 ++++++++++++++++++++++ > > 4 files changed, 42 insertions(+), 7 deletions(-) > > > > diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c > > index 10cc7979ce38..3c53fa6ce64d 100644 > > --- a/fs/iomap/buffered-io.c > > +++ b/fs/iomap/buffered-io.c > > @@ -1458,13 +1458,6 @@ iomap_do_writepage(struct page *page, struct writeback_control *wbc, void *data) > > PF_MEMALLOC)) > > goto redirty; > > > > - /* > > - * Given that we do not allow direct reclaim to call us, we should > > - * never be called in a recursive filesystem reclaim context. > > - */ > > - if (WARN_ON_ONCE(current->flags & PF_MEMALLOC_NOFS)) > > - goto redirty; > > - > > /* > > * Is this page beyond the end of the file? > > * > > diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c > > index 2371187b7615..0da0242d42c3 100644 > > --- a/fs/xfs/xfs_aops.c > > +++ b/fs/xfs/xfs_aops.c > > @@ -568,6 +568,16 @@ xfs_vm_writepage( > > { > > struct xfs_writepage_ctx wpc = { }; > > > > + /* > > + * Given that we do not allow direct reclaim to call us, we should > > + * never be called while in a filesystem transaction. > > + */ > > + if (WARN_ON_ONCE(xfs_trans_context_active())) { > > + redirty_page_for_writepage(wbc, page); > > + unlock_page(page); > > + return 0; > > + } > > + > > return iomap_writepage(page, wbc, &wpc.ctx, &xfs_writeback_ops); > > } > > > > @@ -579,6 +589,13 @@ xfs_vm_writepages( > > struct xfs_writepage_ctx wpc = { }; > > > > xfs_iflags_clear(XFS_I(mapping->host), XFS_ITRUNCATED); > > + /* > > + * Given that we do not allow direct reclaim to call us, we should > > + * never be called while in a filesystem transaction. > > + */ > > + if (WARN_ON_ONCE(xfs_trans_context_active())) > > + return 0; > > + > > return iomap_writepages(mapping, wbc, &wpc.ctx, &xfs_writeback_ops); > > } > > > > diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c > > index fe20398a214e..08d4916ffb13 100644 > > --- a/fs/xfs/xfs_trans.c > > +++ b/fs/xfs/xfs_trans.c > > @@ -124,6 +124,9 @@ xfs_trans_dup( > > tp->t_rtx_res = tp->t_rtx_res_used; > > ntp->t_pflags = tp->t_pflags; > > This one line (ntp->t_pflags = tp->t_pflags) should move to > xfs_trans_context_swap. > Make sense to me. Will update it. > --D > > > > > + /* Associate the new transaction with this thread. */ > > + xfs_trans_context_swap(tp, ntp); > > + > > /* move deferred ops over to the new tp */ > > xfs_defer_move(ntp, tp); > > > > diff --git a/fs/xfs/xfs_trans.h b/fs/xfs/xfs_trans.h > > index 44b11c64a15e..d596a375e3bf 100644 > > --- a/fs/xfs/xfs_trans.h > > +++ b/fs/xfs/xfs_trans.h > > @@ -268,16 +268,38 @@ xfs_trans_item_relog( > > return lip->li_ops->iop_relog(lip, tp); > > } > > > > +static inline bool > > +xfs_trans_context_active(void) > > +{ > > + /* Use journal_info to indicate current is in a transaction */ > > + return current->journal_info != NULL; > > +} > > + > > static inline void > > xfs_trans_context_set(struct xfs_trans *tp) > > { > > + ASSERT(!current->journal_info); > > + current->journal_info = tp; > > tp->t_pflags = memalloc_nofs_save(); > > } > > > > static inline void > > xfs_trans_context_clear(struct xfs_trans *tp) > > { > > + ASSERT(current->journal_info == tp); > > + current->journal_info = NULL; > > memalloc_nofs_restore(tp->t_pflags); > > } > > > > +/* > > + * Transfer the transaction context when rolling a permanent > > + * transaction. > > + */ > > +static inline void > > +xfs_trans_context_swap(struct xfs_trans *tp, struct xfs_trans *ntp) > > +{ > > + ASSERT(current->journal_info == tp); > > + current->journal_info = ntp; > > +} > > + > > #endif /* __XFS_TRANS_H__ */ > > -- > > 2.18.4 > > -- Thanks Yafang
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index 10cc7979ce38..3c53fa6ce64d 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -1458,13 +1458,6 @@ iomap_do_writepage(struct page *page, struct writeback_control *wbc, void *data) PF_MEMALLOC)) goto redirty; - /* - * Given that we do not allow direct reclaim to call us, we should - * never be called in a recursive filesystem reclaim context. - */ - if (WARN_ON_ONCE(current->flags & PF_MEMALLOC_NOFS)) - goto redirty; - /* * Is this page beyond the end of the file? * diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c index 2371187b7615..0da0242d42c3 100644 --- a/fs/xfs/xfs_aops.c +++ b/fs/xfs/xfs_aops.c @@ -568,6 +568,16 @@ xfs_vm_writepage( { struct xfs_writepage_ctx wpc = { }; + /* + * Given that we do not allow direct reclaim to call us, we should + * never be called while in a filesystem transaction. + */ + if (WARN_ON_ONCE(xfs_trans_context_active())) { + redirty_page_for_writepage(wbc, page); + unlock_page(page); + return 0; + } + return iomap_writepage(page, wbc, &wpc.ctx, &xfs_writeback_ops); } @@ -579,6 +589,13 @@ xfs_vm_writepages( struct xfs_writepage_ctx wpc = { }; xfs_iflags_clear(XFS_I(mapping->host), XFS_ITRUNCATED); + /* + * Given that we do not allow direct reclaim to call us, we should + * never be called while in a filesystem transaction. + */ + if (WARN_ON_ONCE(xfs_trans_context_active())) + return 0; + return iomap_writepages(mapping, wbc, &wpc.ctx, &xfs_writeback_ops); } diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c index fe20398a214e..08d4916ffb13 100644 --- a/fs/xfs/xfs_trans.c +++ b/fs/xfs/xfs_trans.c @@ -124,6 +124,9 @@ xfs_trans_dup( tp->t_rtx_res = tp->t_rtx_res_used; ntp->t_pflags = tp->t_pflags; + /* Associate the new transaction with this thread. */ + xfs_trans_context_swap(tp, ntp); + /* move deferred ops over to the new tp */ xfs_defer_move(ntp, tp); diff --git a/fs/xfs/xfs_trans.h b/fs/xfs/xfs_trans.h index 44b11c64a15e..d596a375e3bf 100644 --- a/fs/xfs/xfs_trans.h +++ b/fs/xfs/xfs_trans.h @@ -268,16 +268,38 @@ xfs_trans_item_relog( return lip->li_ops->iop_relog(lip, tp); } +static inline bool +xfs_trans_context_active(void) +{ + /* Use journal_info to indicate current is in a transaction */ + return current->journal_info != NULL; +} + static inline void xfs_trans_context_set(struct xfs_trans *tp) { + ASSERT(!current->journal_info); + current->journal_info = tp; tp->t_pflags = memalloc_nofs_save(); } static inline void xfs_trans_context_clear(struct xfs_trans *tp) { + ASSERT(current->journal_info == tp); + current->journal_info = NULL; memalloc_nofs_restore(tp->t_pflags); } +/* + * Transfer the transaction context when rolling a permanent + * transaction. + */ +static inline void +xfs_trans_context_swap(struct xfs_trans *tp, struct xfs_trans *ntp) +{ + ASSERT(current->journal_info == tp); + current->journal_info = ntp; +} + #endif /* __XFS_TRANS_H__ */
PF_FSTRANS which is used to avoid transaction reservation recursion, is dropped since commit 9070733b4efa ("xfs: abstract PF_FSTRANS to PF_MEMALLOC_NOFS") and commit 7dea19f9ee63 ("mm: introduce memalloc_nofs_{save,restore} API") and replaced by PF_MEMALLOC_NOFS which means to avoid filesystem reclaim recursion. As these two flags have different meanings, we'd better reintroduce PF_FSTRANS back. To avoid wasting the space of PF_* flags in task_struct, we can reuse the current->journal_info to do that, per Willy. As the check of transaction reservation recursion is used by XFS only, we can move the check into xfs_vm_writepage(s), per Dave. To better abstract that behavoir, two new helpers are introduced, as follows, - xfs_trans_context_active To check whehter current is in fs transcation or not - xfs_trans_context_swap Transfer the transaction context when rolling a permanent transaction These two new helpers are instroduced in xfs_trans.h. Cc: Darrick J. Wong <darrick.wong@oracle.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Dave Chinner <david@fromorbit.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: David Howells <dhowells@redhat.com> Cc: Jeff Layton <jlayton@redhat.com> Signed-off-by: Yafang Shao <laoar.shao@gmail.com> --- fs/iomap/buffered-io.c | 7 ------- fs/xfs/xfs_aops.c | 17 +++++++++++++++++ fs/xfs/xfs_trans.c | 3 +++ fs/xfs/xfs_trans.h | 22 ++++++++++++++++++++++ 4 files changed, 42 insertions(+), 7 deletions(-)