Andrew Morton
2018-Oct-31 21:26 UTC
[Ocfs2-devel] [PATCH V2] ocfs2: fix dead lock caused by ocfs2_defrag_extent
Folks, could we please review this patch for upstream inclusion?
Thanks.
From: Larry Chen <lchen at suse.com>
Subject: ocfs2: fix deadlock caused by ocfs2_defrag_extent
ocfs2_defrag_extent may fall into deadlock.
ocfs2_ioctl_move_extents
ocfs2_ioctl_move_extents
ocfs2_move_extents
ocfs2_defrag_extent
ocfs2_lock_allocators_move_extents
ocfs2_reserve_clusters
inode_lock GLOBAL_BITMAP_SYSTEM_INODE
__ocfs2_flush_truncate_log
inode_lock GLOBAL_BITMAP_SYSTEM_INODE
As backtrace shows above, ocfs2_reserve_clusters() will call inode_lock
against the global bitmap if local allocator has not sufficient cluters.
Once global bitmap could meet the demand, ocfs2_reserve_cluster will
return success with global bitmap locked.
After ocfs2_reserve_cluster(), if truncate log is full,
__ocfs2_flush_truncate_log() will definitely fall into deadlock because it
needs to inode_lock global bitmap, which has already been locked.
To fix this bug, we could remove from ocfs2_lock_allocators_move_extents()
the code which intends to lock global allocator, and put the removed code
after __ocfs2_flush_truncate_log().
ocfs2_lock_allocators_move_extents() is refered by 2 places, one is here,
the other does not need the data allocator context, which means this patch
does not affect the caller so far.
[lchen at suse.com: rename ocfs2_lock_allocators_move_extents() to
ocfs2_lock_meta_allocator_move_extents(), add some comments]
Link:
https://urldefense.proofpoint.com/v2/url?u=http-3A__lkml.kernel.org_r_20180902091455.23862-2D1-2Dlchen-40suse.com&d=DwICAg&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=C7gAd4uDxlAvTdc0vmU6X8CMk6L2iDY8-HD0qT6Fo7Y&m=K8aRgOiMescamJW-IuHq-cW4mWedGQv2JTT-2KPy1RI&s=3fQHFtwgixirPeQ5Px4fRBnd_UcSx3rvSsLKLidwESo&eLink:
https://urldefense.proofpoint.com/v2/url?u=http-3A__lkml.kernel.org_r_20180827080121.31145-2D1-2Dlchen-40suse.com&d=DwICAg&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=C7gAd4uDxlAvTdc0vmU6X8CMk6L2iDY8-HD0qT6Fo7Y&m=K8aRgOiMescamJW-IuHq-cW4mWedGQv2JTT-2KPy1RI&s=PQOJREyeElsg_1IlINdSGefNqA6w_cUrI1ezdVxyi7o&eSigned-off-by:
Larry Chen <lchen at suse.com>
Cc: Mark Fasheh <mark at fasheh.com>
Cc: Joel Becker <jlbec at evilplan.org>
Cc: Junxiao Bi <junxiao.bi at oracle.com>
Cc: Joseph Qi <jiangqi903 at gmail.com>
Cc: Changwei Ge <ge.changwei at h3c.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
---
fs/ocfs2/move_extents.c | 40 +++++++++++++++++++++++---------------
1 file changed, 25 insertions(+), 15 deletions(-)
--- a/fs/ocfs2/move_extents.c~fix-dead-lock-caused-by-ocfs2_defrag_extent
+++ a/fs/ocfs2/move_extents.c
@@ -162,7 +162,7 @@ out:
* in some cases, we don't need to reserve clusters, just let data_ac
* be NULL.
*/
-static int ocfs2_lock_allocators_move_extents(struct inode *inode,
+static int ocfs2_lock_meta_allocator_move_extents(struct inode *inode,
struct ocfs2_extent_tree *et,
u32 clusters_to_move,
u32 extents_to_split,
@@ -192,13 +192,6 @@ static int ocfs2_lock_allocators_move_ex
goto out;
}
- if (data_ac) {
- ret = ocfs2_reserve_clusters(osb, clusters_to_move, data_ac);
- if (ret) {
- mlog_errno(ret);
- goto out;
- }
- }
*credits += ocfs2_calc_extend_credits(osb->sb, et->et_root_el);
@@ -257,10 +250,11 @@ static int ocfs2_defrag_extent(struct oc
}
}
- ret = ocfs2_lock_allocators_move_extents(inode, &context->et, *len, 1,
- &context->meta_ac,
- &context->data_ac,
- extra_blocks, &credits);
+ ret = ocfs2_lock_meta_allocator_move_extents(inode, &context->et,
+ *len, 1,
+ &context->meta_ac,
+ &context->data_ac,
+ extra_blocks, &credits);
if (ret) {
mlog_errno(ret);
goto out;
@@ -283,6 +277,21 @@ static int ocfs2_defrag_extent(struct oc
}
}
+ /*
+ * Make sure ocfs2_reserve_cluster is called after
+ * __ocfs2_flush_truncate_log, otherwise, dead lock may happen.
+ *
+ * If ocfs2_reserve_cluster is called
+ * before __ocfs2_flush_truncate_log, dead lock on global bitmap
+ * may happen.
+ *
+ */
+ ret = ocfs2_reserve_clusters(osb, *len, &context->data_ac);
+ if (ret) {
+ mlog_errno(ret);
+ goto out_unlock_mutex;
+ }
+
handle = ocfs2_start_trans(osb, credits);
if (IS_ERR(handle)) {
ret = PTR_ERR(handle);
@@ -600,9 +609,10 @@ static int ocfs2_move_extent(struct ocfs
}
}
- ret = ocfs2_lock_allocators_move_extents(inode, &context->et, len, 1,
- &context->meta_ac,
- NULL, extra_blocks, &credits);
+ ret = ocfs2_lock_meta_allocator_move_extents(inode, &context->et,
+ len, 1,
+ &context->meta_ac,
+ NULL, extra_blocks, &credits);
if (ret) {
mlog_errno(ret);
goto out;
_
Changwei Ge
2018-Nov-01 03:11 UTC
[Ocfs2-devel] [PATCH V2] ocfs2: fix dead lock caused by ocfs2_defrag_extent
Hi Larry, I still have a few tiny comments for your patch, please refer to them. On 2018/11/1 5:28, Andrew Morton wrote:> > Folks, could we please review this patch for upstream inclusion? > > Thanks. > > > From: Larry Chen <lchen at suse.com> > Subject: ocfs2: fix deadlock caused by ocfs2_defrag_extent > > ocfs2_defrag_extent may fall into deadlock. > > ocfs2_ioctl_move_extents > ocfs2_ioctl_move_extents > ocfs2_move_extents > ocfs2_defrag_extent > ocfs2_lock_allocators_move_extents > > ocfs2_reserve_clusters > inode_lock GLOBAL_BITMAP_SYSTEM_INODE > > __ocfs2_flush_truncate_log > inode_lock GLOBAL_BITMAP_SYSTEM_INODE > > As backtrace shows above, ocfs2_reserve_clusters() will call inode_lock > against the global bitmap if local allocator has not sufficient cluters. > Once global bitmap could meet the demand, ocfs2_reserve_cluster will > return success with global bitmap locked. > > After ocfs2_reserve_cluster(), if truncate log is full, > __ocfs2_flush_truncate_log() will definitely fall into deadlock because it > needs to inode_lock global bitmap, which has already been locked. > > To fix this bug, we could remove from ocfs2_lock_allocators_move_extents() > the code which intends to lock global allocator, and put the removed code > after __ocfs2_flush_truncate_log(). > > ocfs2_lock_allocators_move_extents() is refered by 2 places, one is here, > the other does not need the data allocator context, which means this patch > does not affect the caller so far. > > [lchen at suse.com: rename ocfs2_lock_allocators_move_extents() to ocfs2_lock_meta_allocator_move_extents(), add some comments] > Link: https://urldefense.proofpoint.com/v2/url?u=http-3A__lkml.kernel.org_r_20180902091455.23862-2D1-2Dlchen-40suse.com&d=DwICAg&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=C7gAd4uDxlAvTdc0vmU6X8CMk6L2iDY8-HD0qT6Fo7Y&m=K8aRgOiMescamJW-IuHq-cW4mWedGQv2JTT-2KPy1RI&s=3fQHFtwgixirPeQ5Px4fRBnd_UcSx3rvSsLKLidwESo&e> Link: https://urldefense.proofpoint.com/v2/url?u=http-3A__lkml.kernel.org_r_20180827080121.31145-2D1-2Dlchen-40suse.com&d=DwICAg&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=C7gAd4uDxlAvTdc0vmU6X8CMk6L2iDY8-HD0qT6Fo7Y&m=K8aRgOiMescamJW-IuHq-cW4mWedGQv2JTT-2KPy1RI&s=PQOJREyeElsg_1IlINdSGefNqA6w_cUrI1ezdVxyi7o&e> Signed-off-by: Larry Chen <lchen at suse.com> > Cc: Mark Fasheh <mark at fasheh.com> > Cc: Joel Becker <jlbec at evilplan.org> > Cc: Junxiao Bi <junxiao.bi at oracle.com> > Cc: Joseph Qi <jiangqi903 at gmail.com> > Cc: Changwei Ge <ge.changwei at h3c.com> > Signed-off-by: Andrew Morton <akpm at linux-foundation.org> > --- > > fs/ocfs2/move_extents.c | 40 +++++++++++++++++++++++--------------- > 1 file changed, 25 insertions(+), 15 deletions(-) > > --- a/fs/ocfs2/move_extents.c~fix-dead-lock-caused-by-ocfs2_defrag_extent > +++ a/fs/ocfs2/move_extents.c > @@ -162,7 +162,7 @@ out: > * in some cases, we don't need to reserve clusters, just let data_ac > * be NULL. > */ > -static int ocfs2_lock_allocators_move_extents(struct inode *inode, > +static int ocfs2_lock_meta_allocator_move_extents(struct inode *inode, > struct ocfs2_extent_tree *et, > u32 clusters_to_move, > u32 extents_to_split,After removing 'reserving clusters logic' out of this function, I suggest to also change the function header comments. And I think there is no need for arguments _data_ac_ now. Otherwise this patch looks sane to me. Thanks, Changwei> @@ -192,13 +192,6 @@ static int ocfs2_lock_allocators_move_ex > goto out; > } > > - if (data_ac) { > - ret = ocfs2_reserve_clusters(osb, clusters_to_move, data_ac); > - if (ret) { > - mlog_errno(ret); > - goto out; > - } > - } > > *credits += ocfs2_calc_extend_credits(osb->sb, et->et_root_el); > > @@ -257,10 +250,11 @@ static int ocfs2_defrag_extent(struct oc > } > } > > - ret = ocfs2_lock_allocators_move_extents(inode, &context->et, *len, 1, > - &context->meta_ac, > - &context->data_ac, > - extra_blocks, &credits); > + ret = ocfs2_lock_meta_allocator_move_extents(inode, &context->et, > + *len, 1, > + &context->meta_ac, > + &context->data_ac, > + extra_blocks, &credits); > if (ret) { > mlog_errno(ret); > goto out; > @@ -283,6 +277,21 @@ static int ocfs2_defrag_extent(struct oc > } > } > > + /* > + * Make sure ocfs2_reserve_cluster is called after > + * __ocfs2_flush_truncate_log, otherwise, dead lock may happen. > + * > + * If ocfs2_reserve_cluster is called > + * before __ocfs2_flush_truncate_log, dead lock on global bitmap > + * may happen. > + * > + */ > + ret = ocfs2_reserve_clusters(osb, *len, &context->data_ac); > + if (ret) { > + mlog_errno(ret); > + goto out_unlock_mutex; > + } > + > handle = ocfs2_start_trans(osb, credits); > if (IS_ERR(handle)) { > ret = PTR_ERR(handle); > @@ -600,9 +609,10 @@ static int ocfs2_move_extent(struct ocfs > } > } > > - ret = ocfs2_lock_allocators_move_extents(inode, &context->et, len, 1, > - &context->meta_ac, > - NULL, extra_blocks, &credits); > + ret = ocfs2_lock_meta_allocator_move_extents(inode, &context->et, > + len, 1, > + &context->meta_ac, > + NULL, extra_blocks, &credits); > if (ret) { > mlog_errno(ret); > goto out; > _ > > > _______________________________________________ > Ocfs2-devel mailing list > Ocfs2-devel at oss.oracle.com > https://oss.oracle.com/mailman/listinfo/ocfs2-devel >
Joseph Qi
2018-Nov-01 07:25 UTC
[Ocfs2-devel] [PATCH V2] ocfs2: fix dead lock caused by ocfs2_defrag_extent
On 18/11/1 11:11, Changwei Ge wrote:> Hi Larry, > > I still have a few tiny comments for your patch, please refer to them. > > On 2018/11/1 5:28, Andrew Morton wrote: >> >> Folks, could we please review this patch for upstream inclusion? >> >> Thanks. >> >> >> From: Larry Chen <lchen at suse.com> >> Subject: ocfs2: fix deadlock caused by ocfs2_defrag_extent >> >> ocfs2_defrag_extent may fall into deadlock. >> >> ocfs2_ioctl_move_extents >> ocfs2_ioctl_move_extents >> ocfs2_move_extents >> ocfs2_defrag_extent >> ocfs2_lock_allocators_move_extents >> >> ocfs2_reserve_clusters >> inode_lock GLOBAL_BITMAP_SYSTEM_INODE >> >> __ocfs2_flush_truncate_log >> inode_lock GLOBAL_BITMAP_SYSTEM_INODE >> >> As backtrace shows above, ocfs2_reserve_clusters() will call inode_lock >> against the global bitmap if local allocator has not sufficient cluters. >> Once global bitmap could meet the demand, ocfs2_reserve_cluster will >> return success with global bitmap locked. >> >> After ocfs2_reserve_cluster(), if truncate log is full, >> __ocfs2_flush_truncate_log() will definitely fall into deadlock because it >> needs to inode_lock global bitmap, which has already been locked. >> >> To fix this bug, we could remove from ocfs2_lock_allocators_move_extents() >> the code which intends to lock global allocator, and put the removed code >> after __ocfs2_flush_truncate_log(). >> >> ocfs2_lock_allocators_move_extents() is refered by 2 places, one is here, >> the other does not need the data allocator context, which means this patch >> does not affect the caller so far. >> >> [lchen at suse.com: rename ocfs2_lock_allocators_move_extents() to ocfs2_lock_meta_allocator_move_extents(), add some comments] >> Link: https://urldefense.proofpoint.com/v2/url?u=http-3A__lkml.kernel.org_r_20180902091455.23862-2D1-2Dlchen-40suse.com&d=DwICAg&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=C7gAd4uDxlAvTdc0vmU6X8CMk6L2iDY8-HD0qT6Fo7Y&m=K8aRgOiMescamJW-IuHq-cW4mWedGQv2JTT-2KPy1RI&s=3fQHFtwgixirPeQ5Px4fRBnd_UcSx3rvSsLKLidwESo&e>> Link: https://urldefense.proofpoint.com/v2/url?u=http-3A__lkml.kernel.org_r_20180827080121.31145-2D1-2Dlchen-40suse.com&d=DwICAg&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=C7gAd4uDxlAvTdc0vmU6X8CMk6L2iDY8-HD0qT6Fo7Y&m=K8aRgOiMescamJW-IuHq-cW4mWedGQv2JTT-2KPy1RI&s=PQOJREyeElsg_1IlINdSGefNqA6w_cUrI1ezdVxyi7o&e>> Signed-off-by: Larry Chen <lchen at suse.com> >> Cc: Mark Fasheh <mark at fasheh.com> >> Cc: Joel Becker <jlbec at evilplan.org> >> Cc: Junxiao Bi <junxiao.bi at oracle.com> >> Cc: Joseph Qi <jiangqi903 at gmail.com> >> Cc: Changwei Ge <ge.changwei at h3c.com> >> Signed-off-by: Andrew Morton <akpm at linux-foundation.org> >> --- >> >> fs/ocfs2/move_extents.c | 40 +++++++++++++++++++++++--------------- >> 1 file changed, 25 insertions(+), 15 deletions(-) >> >> --- a/fs/ocfs2/move_extents.c~fix-dead-lock-caused-by-ocfs2_defrag_extent >> +++ a/fs/ocfs2/move_extents.c >> @@ -162,7 +162,7 @@ out: >> * in some cases, we don't need to reserve clusters, just let data_ac >> * be NULL. >> */ >> -static int ocfs2_lock_allocators_move_extents(struct inode *inode, >> +static int ocfs2_lock_meta_allocator_move_extents(struct inode *inode, >> struct ocfs2_extent_tree *et, >> u32 clusters_to_move, >> u32 extents_to_split, > > After removing 'reserving clusters logic' out of this function, I suggest to also change the function header comments. > And I think there is no need for arguments _data_ac_ now. > Otherwise this patch looks sane to me. >Agree, I think I have commented this out before. Thanks, Joseph> Thanks, > Changwei > >> @@ -192,13 +192,6 @@ static int ocfs2_lock_allocators_move_ex >> goto out; >> } >> >> - if (data_ac) { >> - ret = ocfs2_reserve_clusters(osb, clusters_to_move, data_ac); >> - if (ret) { >> - mlog_errno(ret); >> - goto out; >> - } >> - } >> >> *credits += ocfs2_calc_extend_credits(osb->sb, et->et_root_el); >> >> @@ -257,10 +250,11 @@ static int ocfs2_defrag_extent(struct oc >> } >> } >> >> - ret = ocfs2_lock_allocators_move_extents(inode, &context->et, *len, 1, >> - &context->meta_ac, >> - &context->data_ac, >> - extra_blocks, &credits); >> + ret = ocfs2_lock_meta_allocator_move_extents(inode, &context->et, >> + *len, 1, >> + &context->meta_ac, >> + &context->data_ac, >> + extra_blocks, &credits); >> if (ret) { >> mlog_errno(ret); >> goto out; >> @@ -283,6 +277,21 @@ static int ocfs2_defrag_extent(struct oc >> } >> } >> >> + /* >> + * Make sure ocfs2_reserve_cluster is called after >> + * __ocfs2_flush_truncate_log, otherwise, dead lock may happen. >> + * >> + * If ocfs2_reserve_cluster is called >> + * before __ocfs2_flush_truncate_log, dead lock on global bitmap >> + * may happen. >> + * >> + */ >> + ret = ocfs2_reserve_clusters(osb, *len, &context->data_ac); >> + if (ret) { >> + mlog_errno(ret); >> + goto out_unlock_mutex; >> + } >> + >> handle = ocfs2_start_trans(osb, credits); >> if (IS_ERR(handle)) { >> ret = PTR_ERR(handle); >> @@ -600,9 +609,10 @@ static int ocfs2_move_extent(struct ocfs >> } >> } >> >> - ret = ocfs2_lock_allocators_move_extents(inode, &context->et, len, 1, >> - &context->meta_ac, >> - NULL, extra_blocks, &credits); >> + ret = ocfs2_lock_meta_allocator_move_extents(inode, &context->et, >> + len, 1, >> + &context->meta_ac, >> + NULL, extra_blocks, &credits); >> if (ret) { >> mlog_errno(ret); >> goto out; >> _ >> >> >> _______________________________________________ >> Ocfs2-devel mailing list >> Ocfs2-devel at oss.oracle.com >> https://oss.oracle.com/mailman/listinfo/ocfs2-devel >> > > _______________________________________________ > Ocfs2-devel mailing list > Ocfs2-devel at oss.oracle.com > https://oss.oracle.com/mailman/listinfo/ocfs2-devel >