| Message ID | 20201208122824.16118-4-laoar.shao@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | xfs: avoid transaction reservation recursion | expand |
On Tue, Dec 08, 2020 at 08:28:23PM +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 | 20 +++++++------------- > 1 file changed, 7 insertions(+), 13 deletions(-) > > diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c > index 11d390f0d3f2..fe20398a214e 100644 > --- a/fs/xfs/xfs_trans.c > +++ b/fs/xfs/xfs_trans.c > @@ -67,6 +67,9 @@ 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. */ > + xfs_trans_context_clear(tp); Don't you need to check if tp is still the current transaction before you clear PF_MEMALLOC_NOFS, now that the NOFS is bound to the lifespan of the transaction itself instead of the reservation? --D > + > 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 +156,6 @@ 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 +163,9 @@ 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 +240,6 @@ xfs_trans_reserve( > tp->t_blk_res = 0; > } > > - xfs_trans_context_clear(tp); > - > return error; > } > > @@ -284,6 +281,8 @@ 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 +877,6 @@ __xfs_trans_commit( > > xfs_log_commit_cil(mp, tp, &commit_lsn, regrant); > > - xfs_trans_context_clear(tp); > xfs_trans_free(tp); > > /* > @@ -911,7 +909,6 @@ __xfs_trans_commit( > tp->t_ticket = NULL; > } > > - xfs_trans_context_clear(tp); > xfs_trans_free_items(tp, !!error); > xfs_trans_free(tp); > > @@ -971,9 +968,6 @@ 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 Wed, Dec 09, 2020 at 09:47:38AM +0800, Yafang Shao wrote: > On Wed, Dec 9, 2020 at 2:59 AM Darrick J. Wong <darrick.wong@oracle.com> wrote: > > > > On Tue, Dec 08, 2020 at 08:28:23PM +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 | 20 +++++++------------- > > > 1 file changed, 7 insertions(+), 13 deletions(-) > > > > > > diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c > > > index 11d390f0d3f2..fe20398a214e 100644 > > > --- a/fs/xfs/xfs_trans.c > > > +++ b/fs/xfs/xfs_trans.c > > > @@ -67,6 +67,9 @@ 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. */ > > > + xfs_trans_context_clear(tp); > > > > Don't you need to check if tp is still the current transaction before > > you clear PF_MEMALLOC_NOFS, now that the NOFS is bound to the lifespan > > of the transaction itself instead of the reservation? > > > > The current->journal_info is always the same with tp here in my verification. > I don't know in which case they are different. I don't know why you changed it from the previous version. > It would be better if you could explain in detail. Anyway I can add > the check with your comment in the next version. xfs_trans_alloc is called to allocate a transaction. We set _NOFS and save the old flags (which don't contain _NOFS) to this transaction. thread logs some changes and calls xfs_trans_roll. xfs_trans_roll calls xfs_trans_dup to duplicate the old transaction. xfs_trans_dup allocates a new transaction, which sets PF_MEMALLOC_NOFS and saves the current context flags (in which _NOFS is set) in the new transaction. xfs_trans_roll then commits the old transaction xfs_trans_commit frees the old transaction xfs_trans_free restores the old context (which didn't have _NOFS) and now we've dropped NOFS incorrectly now we move on with the new transaction, but in the wrong NOFS mode. note that this becomes a lot more obvious once you start fiddling with current->journal_info in the last patch. --D > > > > > > + > > > 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 +156,6 @@ 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 +163,9 @@ 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 +240,6 @@ xfs_trans_reserve( > > > tp->t_blk_res = 0; > > > } > > > > > > - xfs_trans_context_clear(tp); > > > - > > > return error; > > > } > > > > > > @@ -284,6 +281,8 @@ 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 +877,6 @@ __xfs_trans_commit( > > > > > > xfs_log_commit_cil(mp, tp, &commit_lsn, regrant); > > > > > > - xfs_trans_context_clear(tp); > > > xfs_trans_free(tp); > > > > > > /* > > > @@ -911,7 +909,6 @@ __xfs_trans_commit( > > > tp->t_ticket = NULL; > > > } > > > > > > - xfs_trans_context_clear(tp); > > > xfs_trans_free_items(tp, !!error); > > > xfs_trans_free(tp); > > > > > > @@ -971,9 +968,6 @@ 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 > > > > > > > -- > Thanks > Yafang
On Wed, Dec 9, 2020 at 11:53 AM Darrick J. Wong <darrick.wong@oracle.com> wrote: > > On Wed, Dec 09, 2020 at 09:47:38AM +0800, Yafang Shao wrote: > > On Wed, Dec 9, 2020 at 2:59 AM Darrick J. Wong <darrick.wong@oracle.com> wrote: > > > > > > On Tue, Dec 08, 2020 at 08:28:23PM +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 | 20 +++++++------------- > > > > 1 file changed, 7 insertions(+), 13 deletions(-) > > > > > > > > diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c > > > > index 11d390f0d3f2..fe20398a214e 100644 > > > > --- a/fs/xfs/xfs_trans.c > > > > +++ b/fs/xfs/xfs_trans.c > > > > @@ -67,6 +67,9 @@ 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. */ > > > > + xfs_trans_context_clear(tp); > > > > > > Don't you need to check if tp is still the current transaction before > > > you clear PF_MEMALLOC_NOFS, now that the NOFS is bound to the lifespan > > > of the transaction itself instead of the reservation? > > > > > > > The current->journal_info is always the same with tp here in my verification. > > I don't know in which case they are different. > > I don't know why you changed it from the previous version. > I should explain it in the change log. Sorry about that. > > It would be better if you could explain in detail. Anyway I can add > > the check with your comment in the next version. > > xfs_trans_alloc is called to allocate a transaction. We set _NOFS and > save the old flags (which don't contain _NOFS) to this transaction. > > thread logs some changes and calls xfs_trans_roll. > > xfs_trans_roll calls xfs_trans_dup to duplicate the old transaction. > > xfs_trans_dup allocates a new transaction, which sets PF_MEMALLOC_NOFS > and saves the current context flags (in which _NOFS is set) in the new > transaction. > > xfs_trans_roll then commits the old transaction > > xfs_trans_commit frees the old transaction > > xfs_trans_free restores the old context (which didn't have _NOFS) and > now we've dropped NOFS incorrectly > > now we move on with the new transaction, but in the wrong NOFS mode. > > note that this becomes a lot more obvious once you start fiddling with > current->journal_info in the last patch. > Many thanks for the detailed explanation. I missed the rolling transaction. I will add this check in the next version. > --D > > > > > > > > > > + > > > > 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 +156,6 @@ 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 +163,9 @@ 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 +240,6 @@ xfs_trans_reserve( > > > > tp->t_blk_res = 0; > > > > } > > > > > > > > - xfs_trans_context_clear(tp); > > > > - > > > > return error; > > > > } > > > > > > > > @@ -284,6 +281,8 @@ 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 +877,6 @@ __xfs_trans_commit( > > > > > > > > xfs_log_commit_cil(mp, tp, &commit_lsn, regrant); > > > > > > > > - xfs_trans_context_clear(tp); > > > > xfs_trans_free(tp); > > > > > > > > /* > > > > @@ -911,7 +909,6 @@ __xfs_trans_commit( > > > > tp->t_ticket = NULL; > > > > } > > > > > > > > - xfs_trans_context_clear(tp); > > > > xfs_trans_free_items(tp, !!error); > > > > xfs_trans_free(tp); > > > > > > > > @@ -971,9 +968,6 @@ 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 > > > > > > > > > > > > -- > > Thanks > > Yafang
diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c index 11d390f0d3f2..fe20398a214e 100644 --- a/fs/xfs/xfs_trans.c +++ b/fs/xfs/xfs_trans.c @@ -67,6 +67,9 @@ 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. */ + 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 +156,6 @@ 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 +163,9 @@ 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 +240,6 @@ xfs_trans_reserve( tp->t_blk_res = 0; } - xfs_trans_context_clear(tp); - return error; } @@ -284,6 +281,8 @@ 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 +877,6 @@ __xfs_trans_commit( xfs_log_commit_cil(mp, tp, &commit_lsn, regrant); - xfs_trans_context_clear(tp); xfs_trans_free(tp); /* @@ -911,7 +909,6 @@ __xfs_trans_commit( tp->t_ticket = NULL; } - xfs_trans_context_clear(tp); xfs_trans_free_items(tp, !!error); xfs_trans_free(tp); @@ -971,9 +968,6 @@ 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 | 20 +++++++------------- 1 file changed, 7 insertions(+), 13 deletions(-)