| Message ID | 20201209131146.67289-4-laoar.shao@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | xfs: avoid transaction reservation recursion | expand |
On Wed, Dec 09, 2020 at 09:11:45PM +0800, Yafang Shao wrote: > The xfs_trans context should be active after it is allocated, and > deactive when it is freed. > > So these two helpers are refactored as, > - xfs_trans_context_set() > Used in xfs_trans_alloc() > - xfs_trans_context_clear() > Used in xfs_trans_free() > > This patch is based on Darrick's work to fix the issue in xfs/141 in the > earlier version. [1] > > 1. https://lore.kernel.org/linux-xfs/20201104001649.GN7123@magnolia > > 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> > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > --- > fs/xfs/xfs_trans.c | 28 +++++++++++++++------------- > 1 file changed, 15 insertions(+), 13 deletions(-) > > diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c > index 11d390f0d3f2..4f4645329bb2 100644 > --- a/fs/xfs/xfs_trans.c > +++ b/fs/xfs/xfs_trans.c > @@ -67,6 +67,17 @@ xfs_trans_free( > xfs_extent_busy_sort(&tp->t_busy); > xfs_extent_busy_clear(tp->t_mountp, &tp->t_busy, false); > > + > + /* Detach the transaction from this thread. */ > + ASSERT(current->journal_info != NULL); > + /* > + * The PF_MEMALLOC_NOFS is bound to the transaction itself instead > + * of the reservation, so we need to check if tp is still the > + * current transaction before clearing the flag. > + */ > + if (current->journal_info == tp) Um, you don't start setting journal_info until the next patch, so this means that someone who lands on this commit with git bisect will have a xfs with broken logic. Because this is the patch that changes where we set and restore NOFS context, I think you have to introduce xfs_trans_context_swap here, and not in the next patch. I also think the _swap routine has to move the old NOFS state to the new transaction's t_pflags, and then set NOFS in the old transaction's t_pflags so that when we clear the context on the old transaction we don't actually change the thread's NOFS state. --D > + xfs_trans_context_clear(tp); > + > trace_xfs_trans_free(tp, _RET_IP_); > if (!(tp->t_flags & XFS_TRANS_NO_WRITECOUNT)) > sb_end_intwrite(tp->t_mountp->m_super); > @@ -153,9 +164,6 @@ xfs_trans_reserve( > int error = 0; > bool rsvd = (tp->t_flags & XFS_TRANS_RESERVE) != 0; > > - /* Mark this thread as being in a transaction */ > - xfs_trans_context_set(tp); > - > /* > * Attempt to reserve the needed disk blocks by decrementing > * the number needed from the number available. This will > @@ -163,10 +171,9 @@ xfs_trans_reserve( > */ > if (blocks > 0) { > error = xfs_mod_fdblocks(mp, -((int64_t)blocks), rsvd); > - if (error != 0) { > - xfs_trans_context_clear(tp); > + if (error != 0) > return -ENOSPC; > - } > + > tp->t_blk_res += blocks; > } > > @@ -241,8 +248,6 @@ xfs_trans_reserve( > tp->t_blk_res = 0; > } > > - xfs_trans_context_clear(tp); > - > return error; > } > > @@ -284,6 +289,8 @@ xfs_trans_alloc( > INIT_LIST_HEAD(&tp->t_dfops); > tp->t_firstblock = NULLFSBLOCK; > > + /* Mark this thread as being in a transaction */ > + xfs_trans_context_set(tp); > error = xfs_trans_reserve(tp, resp, blocks, rtextents); > if (error) { > xfs_trans_cancel(tp); > @@ -878,7 +885,6 @@ __xfs_trans_commit( > > xfs_log_commit_cil(mp, tp, &commit_lsn, regrant); > > - xfs_trans_context_clear(tp); > xfs_trans_free(tp); > > /* > @@ -911,7 +917,6 @@ __xfs_trans_commit( > tp->t_ticket = NULL; > } > > - xfs_trans_context_clear(tp); > xfs_trans_free_items(tp, !!error); > xfs_trans_free(tp); > > @@ -971,9 +976,6 @@ xfs_trans_cancel( > tp->t_ticket = NULL; > } > > - /* mark this thread as no longer being in a transaction */ > - xfs_trans_context_clear(tp); > - > xfs_trans_free_items(tp, dirty); > xfs_trans_free(tp); > } > -- > 2.18.4 >
On Thu, Dec 10, 2020 at 3:52 AM Darrick J. Wong <darrick.wong@oracle.com> wrote: > > On Wed, Dec 09, 2020 at 09:11:45PM +0800, Yafang Shao wrote: > > The xfs_trans context should be active after it is allocated, and > > deactive when it is freed. > > > > So these two helpers are refactored as, > > - xfs_trans_context_set() > > Used in xfs_trans_alloc() > > - xfs_trans_context_clear() > > Used in xfs_trans_free() > > > > This patch is based on Darrick's work to fix the issue in xfs/141 in the > > earlier version. [1] > > > > 1. https://lore.kernel.org/linux-xfs/20201104001649.GN7123@magnolia > > > > 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> > > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > > --- > > fs/xfs/xfs_trans.c | 28 +++++++++++++++------------- > > 1 file changed, 15 insertions(+), 13 deletions(-) > > > > diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c > > index 11d390f0d3f2..4f4645329bb2 100644 > > --- a/fs/xfs/xfs_trans.c > > +++ b/fs/xfs/xfs_trans.c > > @@ -67,6 +67,17 @@ xfs_trans_free( > > xfs_extent_busy_sort(&tp->t_busy); > > xfs_extent_busy_clear(tp->t_mountp, &tp->t_busy, false); > > > > + > > + /* Detach the transaction from this thread. */ > > + ASSERT(current->journal_info != NULL); > > + /* > > + * The PF_MEMALLOC_NOFS is bound to the transaction itself instead > > + * of the reservation, so we need to check if tp is still the > > + * current transaction before clearing the flag. > > + */ > > + if (current->journal_info == tp) > > Um, you don't start setting journal_info until the next patch, so this > means that someone who lands on this commit with git bisect will have a > xfs with broken logic. > > Because this is the patch that changes where we set and restore NOFS > context, I think you have to introduce xfs_trans_context_swap here, > and not in the next patch. > Thanks for the review. I will change it in the next version. > I also think the _swap routine has to move the old NOFS state to the > new transaction's t_pflags, Sure > and then set NOFS in the old transaction's > t_pflags so that when we clear the context on the old transaction we > don't actually change the thread's NOFS state. > Both thread's NOFS state and thead's journal_info state can't be changed in that case, right ? So should it better be, __xfs_trans_commit(tp, regrant) xfs_trans_free(tp, regrant) if (!regrant). // don't clear the xfs_trans_context if regrant is true. xfs_trans_context_clear() > --D > > > + xfs_trans_context_clear(tp); > > + > > trace_xfs_trans_free(tp, _RET_IP_); > > if (!(tp->t_flags & XFS_TRANS_NO_WRITECOUNT)) > > sb_end_intwrite(tp->t_mountp->m_super); > > @@ -153,9 +164,6 @@ xfs_trans_reserve( > > int error = 0; > > bool rsvd = (tp->t_flags & XFS_TRANS_RESERVE) != 0; > > > > - /* Mark this thread as being in a transaction */ > > - xfs_trans_context_set(tp); > > - > > /* > > * Attempt to reserve the needed disk blocks by decrementing > > * the number needed from the number available. This will > > @@ -163,10 +171,9 @@ xfs_trans_reserve( > > */ > > if (blocks > 0) { > > error = xfs_mod_fdblocks(mp, -((int64_t)blocks), rsvd); > > - if (error != 0) { > > - xfs_trans_context_clear(tp); > > + if (error != 0) > > return -ENOSPC; > > - } > > + > > tp->t_blk_res += blocks; > > } > > > > @@ -241,8 +248,6 @@ xfs_trans_reserve( > > tp->t_blk_res = 0; > > } > > > > - xfs_trans_context_clear(tp); > > - > > return error; > > } > > > > @@ -284,6 +289,8 @@ xfs_trans_alloc( > > INIT_LIST_HEAD(&tp->t_dfops); > > tp->t_firstblock = NULLFSBLOCK; > > > > + /* Mark this thread as being in a transaction */ > > + xfs_trans_context_set(tp); > > error = xfs_trans_reserve(tp, resp, blocks, rtextents); > > if (error) { > > xfs_trans_cancel(tp); > > @@ -878,7 +885,6 @@ __xfs_trans_commit( > > > > xfs_log_commit_cil(mp, tp, &commit_lsn, regrant); > > > > - xfs_trans_context_clear(tp); > > xfs_trans_free(tp); > > > > /* > > @@ -911,7 +917,6 @@ __xfs_trans_commit( > > tp->t_ticket = NULL; > > } > > > > - xfs_trans_context_clear(tp); > > xfs_trans_free_items(tp, !!error); > > xfs_trans_free(tp); > > > > @@ -971,9 +976,6 @@ xfs_trans_cancel( > > tp->t_ticket = NULL; > > } > > > > - /* mark this thread as no longer being in a transaction */ > > - xfs_trans_context_clear(tp); > > - > > xfs_trans_free_items(tp, dirty); > > xfs_trans_free(tp); > > } > > -- > > 2.18.4 > >
On Sun, Dec 13, 2020 at 05:09:02PM +0800, Yafang Shao wrote: > On Thu, Dec 10, 2020 at 3:52 AM Darrick J. Wong <darrick.wong@oracle.com> wrote: > > > > On Wed, Dec 09, 2020 at 09:11:45PM +0800, Yafang Shao wrote: > > > The xfs_trans context should be active after it is allocated, and > > > deactive when it is freed. > > > > > > So these two helpers are refactored as, > > > - xfs_trans_context_set() > > > Used in xfs_trans_alloc() > > > - xfs_trans_context_clear() > > > Used in xfs_trans_free() > > > > > > This patch is based on Darrick's work to fix the issue in xfs/141 in the > > > earlier version. [1] > > > > > > 1. https://lore.kernel.org/linux-xfs/20201104001649.GN7123@magnolia > > > > > > 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> > > > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > > > --- > > > fs/xfs/xfs_trans.c | 28 +++++++++++++++------------- > > > 1 file changed, 15 insertions(+), 13 deletions(-) > > > > > > diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c > > > index 11d390f0d3f2..4f4645329bb2 100644 > > > --- a/fs/xfs/xfs_trans.c > > > +++ b/fs/xfs/xfs_trans.c > > > @@ -67,6 +67,17 @@ xfs_trans_free( > > > xfs_extent_busy_sort(&tp->t_busy); > > > xfs_extent_busy_clear(tp->t_mountp, &tp->t_busy, false); > > > > > > + > > > + /* Detach the transaction from this thread. */ > > > + ASSERT(current->journal_info != NULL); > > > + /* > > > + * The PF_MEMALLOC_NOFS is bound to the transaction itself instead > > > + * of the reservation, so we need to check if tp is still the > > > + * current transaction before clearing the flag. > > > + */ > > > + if (current->journal_info == tp) > > > > Um, you don't start setting journal_info until the next patch, so this > > means that someone who lands on this commit with git bisect will have a > > xfs with broken logic. > > > > Because this is the patch that changes where we set and restore NOFS > > context, I think you have to introduce xfs_trans_context_swap here, > > and not in the next patch. > > > > Thanks for the review. I will change it in the next version. > > > I also think the _swap routine has to move the old NOFS state to the > > new transaction's t_pflags, > > Sure > > > and then set NOFS in the old transaction's > > t_pflags so that when we clear the context on the old transaction we > > don't actually change the thread's NOFS state. > > > > Both thread's NOFS state and thead's journal_info state can't be > changed in that case, right ? > So should it better be, > > __xfs_trans_commit(tp, regrant) > xfs_trans_free(tp, regrant) > if (!regrant). // don't clear the xfs_trans_context if > regrant is true. > xfs_trans_context_clear() No. You are trying to make this way more complex than it needs to be. The logic in the core XFS code is *already correct* and all we need to do is move that logic to wrapper functions, then slightly modify the implementation inside the wrapper functions. That is, xfs_trans_context_clear() should end up like this: static inline void xfs_trans_context_clear(struct xfs_trans *tp) { /* * If xfs_trans_context_swap() handed the NOFS context to a * new transaction we do not clear the context here. */ if (current->journal_info != tp) return; current->journal_info = NULL; memalloc_nofs_restore(tp->t_pflags); } -Dave.
On Tue, Dec 15, 2020 at 5:08 AM Dave Chinner <david@fromorbit.com> wrote: > > On Sun, Dec 13, 2020 at 05:09:02PM +0800, Yafang Shao wrote: > > On Thu, Dec 10, 2020 at 3:52 AM Darrick J. Wong <darrick.wong@oracle.com> wrote: > > > > > > On Wed, Dec 09, 2020 at 09:11:45PM +0800, Yafang Shao wrote: > > > > The xfs_trans context should be active after it is allocated, and > > > > deactive when it is freed. > > > > > > > > So these two helpers are refactored as, > > > > - xfs_trans_context_set() > > > > Used in xfs_trans_alloc() > > > > - xfs_trans_context_clear() > > > > Used in xfs_trans_free() > > > > > > > > This patch is based on Darrick's work to fix the issue in xfs/141 in the > > > > earlier version. [1] > > > > > > > > 1. https://lore.kernel.org/linux-xfs/20201104001649.GN7123@magnolia > > > > > > > > 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> > > > > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > > > > --- > > > > fs/xfs/xfs_trans.c | 28 +++++++++++++++------------- > > > > 1 file changed, 15 insertions(+), 13 deletions(-) > > > > > > > > diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c > > > > index 11d390f0d3f2..4f4645329bb2 100644 > > > > --- a/fs/xfs/xfs_trans.c > > > > +++ b/fs/xfs/xfs_trans.c > > > > @@ -67,6 +67,17 @@ xfs_trans_free( > > > > xfs_extent_busy_sort(&tp->t_busy); > > > > xfs_extent_busy_clear(tp->t_mountp, &tp->t_busy, false); > > > > > > > > + > > > > + /* Detach the transaction from this thread. */ > > > > + ASSERT(current->journal_info != NULL); > > > > + /* > > > > + * The PF_MEMALLOC_NOFS is bound to the transaction itself instead > > > > + * of the reservation, so we need to check if tp is still the > > > > + * current transaction before clearing the flag. > > > > + */ > > > > + if (current->journal_info == tp) > > > > > > Um, you don't start setting journal_info until the next patch, so this > > > means that someone who lands on this commit with git bisect will have a > > > xfs with broken logic. > > > > > > Because this is the patch that changes where we set and restore NOFS > > > context, I think you have to introduce xfs_trans_context_swap here, > > > and not in the next patch. > > > > > > > Thanks for the review. I will change it in the next version. > > > > > I also think the _swap routine has to move the old NOFS state to the > > > new transaction's t_pflags, > > > > Sure > > > > > and then set NOFS in the old transaction's > > > t_pflags so that when we clear the context on the old transaction we > > > don't actually change the thread's NOFS state. > > > > > > > Both thread's NOFS state and thead's journal_info state can't be > > changed in that case, right ? > > So should it better be, > > > > __xfs_trans_commit(tp, regrant) > > xfs_trans_free(tp, regrant) > > if (!regrant). // don't clear the xfs_trans_context if > > regrant is true. > > xfs_trans_context_clear() > > No. You are trying to make this way more complex than it needs to be. > The logic in the core XFS code is *already correct* and all we need > to do is move that logic to wrapper functions, then slightly modify > the implementation inside the wrapper functions. > Thanks for the explanation. > > That is, xfs_trans_context_clear() should end up like this: > Agreed. > static inline void > xfs_trans_context_clear(struct xfs_trans *tp) > { > /* > * If xfs_trans_context_swap() handed the NOFS context to a > * new transaction we do not clear the context here. > */ > if (current->journal_info != tp) current->journal_info hasn't been used in patch #3, that will make patch #3 a little more complex. We have to do some workaround in patch #3. I will think about it. > return; > current->journal_info = NULL; > memalloc_nofs_restore(tp->t_pflags); > } > > -Dave. > -- > Dave Chinner > david@fromorbit.com
On Tue, Dec 15, 2020 at 08:42:08AM +0800, Yafang Shao wrote: > On Tue, Dec 15, 2020 at 5:08 AM Dave Chinner <david@fromorbit.com> wrote: > > On Sun, Dec 13, 2020 at 05:09:02PM +0800, Yafang Shao wrote: > > > On Thu, Dec 10, 2020 at 3:52 AM Darrick J. Wong <darrick.wong@oracle.com> wrote: > > > > On Wed, Dec 09, 2020 at 09:11:45PM +0800, Yafang Shao wrote: > > static inline void > > xfs_trans_context_clear(struct xfs_trans *tp) > > { > > /* > > * If xfs_trans_context_swap() handed the NOFS context to a > > * new transaction we do not clear the context here. > > */ > > if (current->journal_info != tp) > > current->journal_info hasn't been used in patch #3, that will make > patch #3 a little more complex. > We have to do some workaround in patch #3. I will think about it. What I wrote is how the function should look at the end of the patch series. Do not add the current->journal_info parts of it until the patch that introduces the current->journal_info tracking. -Dave.
On Tue, Dec 15, 2020 at 9:12 AM Dave Chinner <david@fromorbit.com> wrote: > > On Tue, Dec 15, 2020 at 08:42:08AM +0800, Yafang Shao wrote: > > On Tue, Dec 15, 2020 at 5:08 AM Dave Chinner <david@fromorbit.com> wrote: > > > On Sun, Dec 13, 2020 at 05:09:02PM +0800, Yafang Shao wrote: > > > > On Thu, Dec 10, 2020 at 3:52 AM Darrick J. Wong <darrick.wong@oracle.com> wrote: > > > > > On Wed, Dec 09, 2020 at 09:11:45PM +0800, Yafang Shao wrote: > > > static inline void > > > xfs_trans_context_clear(struct xfs_trans *tp) > > > { > > > /* > > > * If xfs_trans_context_swap() handed the NOFS context to a > > > * new transaction we do not clear the context here. > > > */ > > > if (current->journal_info != tp) > > > > current->journal_info hasn't been used in patch #3, that will make > > patch #3 a little more complex. > > We have to do some workaround in patch #3. I will think about it. > > What I wrote is how the function should look at the end of the patch > series. Do not add the current->journal_info parts of it until the > patch that introduces the current->journal_info tracking. > I know what you meant. While I mean we have to do some hack, as suggested by Darrrick that "set NOFS in the old transaction's t_pflags so that when we clear the context on the old transaction we don't actually change the thread's NOFS state." in patch #3 and then remove it in patch #4.
diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c index 11d390f0d3f2..4f4645329bb2 100644 --- a/fs/xfs/xfs_trans.c +++ b/fs/xfs/xfs_trans.c @@ -67,6 +67,17 @@ xfs_trans_free( xfs_extent_busy_sort(&tp->t_busy); xfs_extent_busy_clear(tp->t_mountp, &tp->t_busy, false); + + /* Detach the transaction from this thread. */ + ASSERT(current->journal_info != NULL); + /* + * The PF_MEMALLOC_NOFS is bound to the transaction itself instead + * of the reservation, so we need to check if tp is still the + * current transaction before clearing the flag. + */ + if (current->journal_info == tp) + xfs_trans_context_clear(tp); + trace_xfs_trans_free(tp, _RET_IP_); if (!(tp->t_flags & XFS_TRANS_NO_WRITECOUNT)) sb_end_intwrite(tp->t_mountp->m_super); @@ -153,9 +164,6 @@ xfs_trans_reserve( int error = 0; bool rsvd = (tp->t_flags & XFS_TRANS_RESERVE) != 0; - /* Mark this thread as being in a transaction */ - xfs_trans_context_set(tp); - /* * Attempt to reserve the needed disk blocks by decrementing * the number needed from the number available. This will @@ -163,10 +171,9 @@ xfs_trans_reserve( */ if (blocks > 0) { error = xfs_mod_fdblocks(mp, -((int64_t)blocks), rsvd); - if (error != 0) { - xfs_trans_context_clear(tp); + if (error != 0) return -ENOSPC; - } + tp->t_blk_res += blocks; } @@ -241,8 +248,6 @@ xfs_trans_reserve( tp->t_blk_res = 0; } - xfs_trans_context_clear(tp); - return error; } @@ -284,6 +289,8 @@ xfs_trans_alloc( INIT_LIST_HEAD(&tp->t_dfops); tp->t_firstblock = NULLFSBLOCK; + /* Mark this thread as being in a transaction */ + xfs_trans_context_set(tp); error = xfs_trans_reserve(tp, resp, blocks, rtextents); if (error) { xfs_trans_cancel(tp); @@ -878,7 +885,6 @@ __xfs_trans_commit( xfs_log_commit_cil(mp, tp, &commit_lsn, regrant); - xfs_trans_context_clear(tp); xfs_trans_free(tp); /* @@ -911,7 +917,6 @@ __xfs_trans_commit( tp->t_ticket = NULL; } - xfs_trans_context_clear(tp); xfs_trans_free_items(tp, !!error); xfs_trans_free(tp); @@ -971,9 +976,6 @@ xfs_trans_cancel( tp->t_ticket = NULL; } - /* mark this thread as no longer being in a transaction */ - xfs_trans_context_clear(tp); - xfs_trans_free_items(tp, dirty); xfs_trans_free(tp); }
The xfs_trans context should be active after it is allocated, and deactive when it is freed. So these two helpers are refactored as, - xfs_trans_context_set() Used in xfs_trans_alloc() - xfs_trans_context_clear() Used in xfs_trans_free() This patch is based on Darrick's work to fix the issue in xfs/141 in the earlier version. [1] 1. https://lore.kernel.org/linux-xfs/20201104001649.GN7123@magnolia 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> Signed-off-by: Yafang Shao <laoar.shao@gmail.com> --- fs/xfs/xfs_trans.c | 28 +++++++++++++++------------- 1 file changed, 15 insertions(+), 13 deletions(-)