* [Ocfs2-devel] [PATCH V1 RFC 1/1] Subject: [[PATCH V1 RFC] 1/1] ocfs2: race between searching chunks and release journal_head from buffer_head
@ 2021-10-20 5:15 Gautham Ananthakrishna
2021-10-20 5:15 ` [Ocfs2-devel] [PATCH V1 RFC " Gautham Ananthakrishna
2021-10-20 5:17 ` [Ocfs2-devel] [PATCH V1 RFC 1/1] Subject: [[PATCH V1 RFC] " Gautham Ananthakrishna
0 siblings, 2 replies; 4+ messages in thread
From: Gautham Ananthakrishna @ 2021-10-20 5:15 UTC (permalink / raw)
To: ocfs2-devel; +Cc: rajesh.sivaramasubramaniom, gautham.ananthakrishna
Encountered a race between ocfs2_test_bg_bit_allocatable() and
jbd2_journal_put_journal_head() resulting in the below vmcore.
PID: 106879 TASK: ffff880244ba9c00 CPU: 2 COMMAND: "loop3"
0 [ffff8802435ff1c0] panic at ffffffff816ed175
1 [ffff8802435ff240] oops_end at ffffffff8101a7c9
2 [ffff8802435ff270] no_context at ffffffff8106eccf
3 [ffff8802435ff2e0] __bad_area_nosemaphore at ffffffff8106ef9d
4 [ffff8802435ff330] bad_area_nosemaphore at ffffffff8106f143
5 [ffff8802435ff340] __do_page_fault at ffffffff8106f80b
6 [ffff8802435ff3a0] do_page_fault at ffffffff8106fc2f
7 [ffff8802435ff3e0] page_fault at ffffffff816fd667
[exception RIP: ocfs2_block_group_find_clear_bits+316]
RIP: ffffffffc11ef6fc RSP: ffff8802435ff498 RFLAGS: 00010206
RAX: 0000000000003918 RBX: 0000000000000001 RCX: 0000000000000018
RDX: 0000000000003918 RSI: 0000000000000000 RDI: ffff880060194040
RBP: ffff8802435ff4f8 R8: ffffffffff000000 R9: ffffffffffffffff
R10: ffff8802435ff730 R11: ffff8802a94e5800 R12: 0000000000000007
R13: 0000000000007e00 R14: 0000000000003918 R15: ffff88017c973a28
ORIG_RAX: ffffffffffffffff CS: e030 SS: e02b
8 [ffff8802435ff490] ocfs2_block_group_find_clear_bits at ffffffffc11ef680 [ocfs2]
9 [ffff8802435ff500] ocfs2_cluster_group_search at ffffffffc11ef916 [ocfs2]
10 [ffff8802435ff580] ocfs2_search_chain at ffffffffc11f0fb6 [ocfs2]
11 [ffff8802435ff660] ocfs2_claim_suballoc_bits at ffffffffc11f1b1b [ocfs2]
12 [ffff8802435ff6f0] __ocfs2_claim_clusters at ffffffffc11f32cb [ocfs2]
13 [ffff8802435ff770] ocfs2_claim_clusters at ffffffffc11f5caf [ocfs2]
14 [ffff8802435ff780] ocfs2_local_alloc_slide_window at ffffffffc11cc0db [ocfs2]
15 [ffff8802435ff820] ocfs2_reserve_local_alloc_bits at ffffffffc11ce53f [ocfs2]
16 [ffff8802435ff890] ocfs2_reserve_clusters_with_limit at ffffffffc11f59b5 [ocfs2]
17 [ffff8802435ff8e0] ocfs2_reserve_clusters at ffffffffc11f5c88 [ocfs2]
18 [ffff8802435ff8f0] ocfs2_lock_refcount_allocators at ffffffffc11dc169 [ocfs2]
19 [ffff8802435ff960] ocfs2_make_clusters_writable at ffffffffc11e4274 [ocfs2]
20 [ffff8802435ffa50] ocfs2_replace_cow at ffffffffc11e4df1 [ocfs2]
21 [ffff8802435ffac0] ocfs2_refcount_cow at ffffffffc11e54b1 [ocfs2]
22 [ffff8802435ffb80] ocfs2_file_write_iter at ffffffffc11bf8f4 [ocfs2]
23 [ffff8802435ffcd0] lo_rw_aio at ffffffff814a1b5d
24 [ffff8802435ffd80] loop_queue_work at ffffffff814a2802
25 [ffff8802435ffe60] kthread_worker_fn at ffffffff810a80d2
26 [ffff8802435ffec0] kthread at ffffffff810a7afb
27 [ffff8802435fff50] ret_from_fork at ffffffff816f7da1
When ocfs2_test_bg_bit_allocatable() called bh2jh(bg_bh), the bg_bh->b_private
NULL as jbd2_journal_put_journal_head() raced and released the jounal head
from the buffer head. Needed to take bit lock for the bit 'BH_JournalHead'
to fix this race.
Signed-off-by: Gautham Ananthakrishna <gautham.ananthakrishna@oracle.com>
---
fs/ocfs2/suballoc.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c
index 8521942..86f33f2 100644
--- a/fs/ocfs2/suballoc.c
+++ b/fs/ocfs2/suballoc.c
@@ -1256,9 +1256,17 @@ static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh,
if (ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap))
return 0;
+ /* Fast path */
if (!buffer_jbd(bg_bh))
return 1;
+ /* Slow path */
+ jbd_lock_bh_journal_head(bg_bh);
+ if (!buffer_jbd(bg_bh)){
+ jbd_unlock_bh_journal_head(bg_bh);
+ return 1;
+ }
+
jh = bh2jh(bg_bh);
spin_lock(&jh->b_state_lock);
bg = (struct ocfs2_group_desc *) jh->b_committed_data;
@@ -1267,6 +1275,7 @@ static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh,
else
ret = 1;
spin_unlock(&jh->b_state_lock);
+ jbd_unlock_bh_journal_head(bg_bh);
return ret;
}
--
1.8.3.1
_______________________________________________
Ocfs2-devel mailing list
Ocfs2-devel@oss.oracle.com
https://oss.oracle.com/mailman/listinfo/ocfs2-devel
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [Ocfs2-devel] [PATCH V1 RFC 1/1] ocfs2: race between searching chunks and release journal_head from buffer_head
2021-10-20 5:15 [Ocfs2-devel] [PATCH V1 RFC 1/1] Subject: [[PATCH V1 RFC] 1/1] ocfs2: race between searching chunks and release journal_head from buffer_head Gautham Ananthakrishna
@ 2021-10-20 5:15 ` Gautham Ananthakrishna
2021-10-20 5:17 ` Gautham Ananthakrishna
2021-10-20 5:17 ` [Ocfs2-devel] [PATCH V1 RFC 1/1] Subject: [[PATCH V1 RFC] " Gautham Ananthakrishna
1 sibling, 1 reply; 4+ messages in thread
From: Gautham Ananthakrishna @ 2021-10-20 5:15 UTC (permalink / raw)
To: ocfs2-devel; +Cc: rajesh.sivaramasubramaniom, gautham.ananthakrishna
Encountered a race between ocfs2_test_bg_bit_allocatable() and
jbd2_journal_put_journal_head() resulting in the below vmcore.
PID: 106879 TASK: ffff880244ba9c00 CPU: 2 COMMAND: "loop3"
0 [ffff8802435ff1c0] panic at ffffffff816ed175
1 [ffff8802435ff240] oops_end at ffffffff8101a7c9
2 [ffff8802435ff270] no_context at ffffffff8106eccf
3 [ffff8802435ff2e0] __bad_area_nosemaphore at ffffffff8106ef9d
4 [ffff8802435ff330] bad_area_nosemaphore at ffffffff8106f143
5 [ffff8802435ff340] __do_page_fault at ffffffff8106f80b
6 [ffff8802435ff3a0] do_page_fault at ffffffff8106fc2f
7 [ffff8802435ff3e0] page_fault at ffffffff816fd667
[exception RIP: ocfs2_block_group_find_clear_bits+316]
RIP: ffffffffc11ef6fc RSP: ffff8802435ff498 RFLAGS: 00010206
RAX: 0000000000003918 RBX: 0000000000000001 RCX: 0000000000000018
RDX: 0000000000003918 RSI: 0000000000000000 RDI: ffff880060194040
RBP: ffff8802435ff4f8 R8: ffffffffff000000 R9: ffffffffffffffff
R10: ffff8802435ff730 R11: ffff8802a94e5800 R12: 0000000000000007
R13: 0000000000007e00 R14: 0000000000003918 R15: ffff88017c973a28
ORIG_RAX: ffffffffffffffff CS: e030 SS: e02b
8 [ffff8802435ff490] ocfs2_block_group_find_clear_bits at ffffffffc11ef680 [ocfs2]
9 [ffff8802435ff500] ocfs2_cluster_group_search at ffffffffc11ef916 [ocfs2]
10 [ffff8802435ff580] ocfs2_search_chain at ffffffffc11f0fb6 [ocfs2]
11 [ffff8802435ff660] ocfs2_claim_suballoc_bits at ffffffffc11f1b1b [ocfs2]
12 [ffff8802435ff6f0] __ocfs2_claim_clusters at ffffffffc11f32cb [ocfs2]
13 [ffff8802435ff770] ocfs2_claim_clusters at ffffffffc11f5caf [ocfs2]
14 [ffff8802435ff780] ocfs2_local_alloc_slide_window at ffffffffc11cc0db [ocfs2]
15 [ffff8802435ff820] ocfs2_reserve_local_alloc_bits at ffffffffc11ce53f [ocfs2]
16 [ffff8802435ff890] ocfs2_reserve_clusters_with_limit at ffffffffc11f59b5 [ocfs2]
17 [ffff8802435ff8e0] ocfs2_reserve_clusters at ffffffffc11f5c88 [ocfs2]
18 [ffff8802435ff8f0] ocfs2_lock_refcount_allocators at ffffffffc11dc169 [ocfs2]
19 [ffff8802435ff960] ocfs2_make_clusters_writable at ffffffffc11e4274 [ocfs2]
20 [ffff8802435ffa50] ocfs2_replace_cow at ffffffffc11e4df1 [ocfs2]
21 [ffff8802435ffac0] ocfs2_refcount_cow at ffffffffc11e54b1 [ocfs2]
22 [ffff8802435ffb80] ocfs2_file_write_iter at ffffffffc11bf8f4 [ocfs2]
23 [ffff8802435ffcd0] lo_rw_aio at ffffffff814a1b5d
24 [ffff8802435ffd80] loop_queue_work at ffffffff814a2802
25 [ffff8802435ffe60] kthread_worker_fn at ffffffff810a80d2
26 [ffff8802435ffec0] kthread at ffffffff810a7afb
27 [ffff8802435fff50] ret_from_fork at ffffffff816f7da1
When ocfs2_test_bg_bit_allocatable() called bh2jh(bg_bh), the bg_bh->b_private
NULL as jbd2_journal_put_journal_head() raced and released the jounal head
from the buffer head. Needed to take bit lock for the bit 'BH_JournalHead'
to fix this race.
Signed-off-by: Gautham Ananthakrishna <gautham.ananthakrishna@oracle.com>
---
fs/ocfs2/suballoc.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c
index 8521942..86f33f2 100644
--- a/fs/ocfs2/suballoc.c
+++ b/fs/ocfs2/suballoc.c
@@ -1256,9 +1256,17 @@ static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh,
if (ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap))
return 0;
+ /* Fast path */
if (!buffer_jbd(bg_bh))
return 1;
+ /* Slow path */
+ jbd_lock_bh_journal_head(bg_bh);
+ if (!buffer_jbd(bg_bh)){
+ jbd_unlock_bh_journal_head(bg_bh);
+ return 1;
+ }
+
jh = bh2jh(bg_bh);
spin_lock(&jh->b_state_lock);
bg = (struct ocfs2_group_desc *) jh->b_committed_data;
@@ -1267,6 +1275,7 @@ static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh,
else
ret = 1;
spin_unlock(&jh->b_state_lock);
+ jbd_unlock_bh_journal_head(bg_bh);
return ret;
}
--
1.8.3.1
_______________________________________________
Ocfs2-devel mailing list
Ocfs2-devel@oss.oracle.com
https://oss.oracle.com/mailman/listinfo/ocfs2-devel
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [Ocfs2-devel] [PATCH V1 RFC 1/1] ocfs2: race between searching chunks and release journal_head from buffer_head
2021-10-20 5:15 ` [Ocfs2-devel] [PATCH V1 RFC " Gautham Ananthakrishna
@ 2021-10-20 5:17 ` Gautham Ananthakrishna
0 siblings, 0 replies; 4+ messages in thread
From: Gautham Ananthakrishna @ 2021-10-20 5:17 UTC (permalink / raw)
To: Gautham Ananthakrishna, ocfs2-devel; +Cc: Rajesh Sivaramasubramaniom
Please ignore this patch I will be resending it
Thanks,
Gautham.
-----Original Message-----
From: Gautham Ananthakrishna <gautham.ananthakrishna@oracle.com>
Sent: Wednesday, October 20, 2021 10:45 AM
To: ocfs2-devel@oss.oracle.com
Cc: joseph.qi@linux.alibaba.com; Junxiao Bi <junxiao.bi@oracle.com>; Rajesh Sivaramasubramaniom <rajesh.sivaramasubramaniom@oracle.com>; Gautham Ananthakrishna <gautham.ananthakrishna@oracle.com>
Subject: [PATCH V1 RFC 1/1] ocfs2: race between searching chunks and release journal_head from buffer_head
Encountered a race between ocfs2_test_bg_bit_allocatable() and
jbd2_journal_put_journal_head() resulting in the below vmcore.
PID: 106879 TASK: ffff880244ba9c00 CPU: 2 COMMAND: "loop3"
0 [ffff8802435ff1c0] panic at ffffffff816ed175
1 [ffff8802435ff240] oops_end at ffffffff8101a7c9
2 [ffff8802435ff270] no_context at ffffffff8106eccf
3 [ffff8802435ff2e0] __bad_area_nosemaphore at ffffffff8106ef9d
4 [ffff8802435ff330] bad_area_nosemaphore at ffffffff8106f143
5 [ffff8802435ff340] __do_page_fault at ffffffff8106f80b
6 [ffff8802435ff3a0] do_page_fault at ffffffff8106fc2f
7 [ffff8802435ff3e0] page_fault at ffffffff816fd667
[exception RIP: ocfs2_block_group_find_clear_bits+316]
RIP: ffffffffc11ef6fc RSP: ffff8802435ff498 RFLAGS: 00010206
RAX: 0000000000003918 RBX: 0000000000000001 RCX: 0000000000000018
RDX: 0000000000003918 RSI: 0000000000000000 RDI: ffff880060194040
RBP: ffff8802435ff4f8 R8: ffffffffff000000 R9: ffffffffffffffff
R10: ffff8802435ff730 R11: ffff8802a94e5800 R12: 0000000000000007
R13: 0000000000007e00 R14: 0000000000003918 R15: ffff88017c973a28
ORIG_RAX: ffffffffffffffff CS: e030 SS: e02b
8 [ffff8802435ff490] ocfs2_block_group_find_clear_bits at ffffffffc11ef680 [ocfs2]
9 [ffff8802435ff500] ocfs2_cluster_group_search at ffffffffc11ef916 [ocfs2]
10 [ffff8802435ff580] ocfs2_search_chain at ffffffffc11f0fb6 [ocfs2]
11 [ffff8802435ff660] ocfs2_claim_suballoc_bits at ffffffffc11f1b1b [ocfs2]
12 [ffff8802435ff6f0] __ocfs2_claim_clusters at ffffffffc11f32cb [ocfs2]
13 [ffff8802435ff770] ocfs2_claim_clusters at ffffffffc11f5caf [ocfs2]
14 [ffff8802435ff780] ocfs2_local_alloc_slide_window at ffffffffc11cc0db [ocfs2]
15 [ffff8802435ff820] ocfs2_reserve_local_alloc_bits at ffffffffc11ce53f [ocfs2]
16 [ffff8802435ff890] ocfs2_reserve_clusters_with_limit at ffffffffc11f59b5 [ocfs2]
17 [ffff8802435ff8e0] ocfs2_reserve_clusters at ffffffffc11f5c88 [ocfs2]
18 [ffff8802435ff8f0] ocfs2_lock_refcount_allocators at ffffffffc11dc169 [ocfs2]
19 [ffff8802435ff960] ocfs2_make_clusters_writable at ffffffffc11e4274 [ocfs2]
20 [ffff8802435ffa50] ocfs2_replace_cow at ffffffffc11e4df1 [ocfs2]
21 [ffff8802435ffac0] ocfs2_refcount_cow at ffffffffc11e54b1 [ocfs2]
22 [ffff8802435ffb80] ocfs2_file_write_iter at ffffffffc11bf8f4 [ocfs2]
23 [ffff8802435ffcd0] lo_rw_aio at ffffffff814a1b5d
24 [ffff8802435ffd80] loop_queue_work at ffffffff814a2802
25 [ffff8802435ffe60] kthread_worker_fn at ffffffff810a80d2
26 [ffff8802435ffec0] kthread at ffffffff810a7afb
27 [ffff8802435fff50] ret_from_fork at ffffffff816f7da1
When ocfs2_test_bg_bit_allocatable() called bh2jh(bg_bh), the bg_bh->b_private NULL as jbd2_journal_put_journal_head() raced and released the jounal head from the buffer head. Needed to take bit lock for the bit 'BH_JournalHead'
to fix this race.
Signed-off-by: Gautham Ananthakrishna <gautham.ananthakrishna@oracle.com>
---
fs/ocfs2/suballoc.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c index 8521942..86f33f2 100644
--- a/fs/ocfs2/suballoc.c
+++ b/fs/ocfs2/suballoc.c
@@ -1256,9 +1256,17 @@ static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh,
if (ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap))
return 0;
+ /* Fast path */
if (!buffer_jbd(bg_bh))
return 1;
+ /* Slow path */
+ jbd_lock_bh_journal_head(bg_bh);
+ if (!buffer_jbd(bg_bh)){
+ jbd_unlock_bh_journal_head(bg_bh);
+ return 1;
+ }
+
jh = bh2jh(bg_bh);
spin_lock(&jh->b_state_lock);
bg = (struct ocfs2_group_desc *) jh->b_committed_data; @@ -1267,6 +1275,7 @@ static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh,
else
ret = 1;
spin_unlock(&jh->b_state_lock);
+ jbd_unlock_bh_journal_head(bg_bh);
return ret;
}
--
1.8.3.1
_______________________________________________
Ocfs2-devel mailing list
Ocfs2-devel@oss.oracle.com
https://oss.oracle.com/mailman/listinfo/ocfs2-devel
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Ocfs2-devel] [PATCH V1 RFC 1/1] Subject: [[PATCH V1 RFC] 1/1] ocfs2: race between searching chunks and release journal_head from buffer_head
2021-10-20 5:15 [Ocfs2-devel] [PATCH V1 RFC 1/1] Subject: [[PATCH V1 RFC] 1/1] ocfs2: race between searching chunks and release journal_head from buffer_head Gautham Ananthakrishna
2021-10-20 5:15 ` [Ocfs2-devel] [PATCH V1 RFC " Gautham Ananthakrishna
@ 2021-10-20 5:17 ` Gautham Ananthakrishna
1 sibling, 0 replies; 4+ messages in thread
From: Gautham Ananthakrishna @ 2021-10-20 5:17 UTC (permalink / raw)
To: Gautham Ananthakrishna, ocfs2-devel; +Cc: Rajesh Sivaramasubramaniom
Please ignore this patch I will be resending it
Thanks,
Gautham.
-----Original Message-----
From: Gautham Ananthakrishna <gautham.ananthakrishna@oracle.com>
Sent: Wednesday, October 20, 2021 10:45 AM
To: ocfs2-devel@oss.oracle.com
Cc: joseph.qi@linux.alibaba.com; Junxiao Bi <junxiao.bi@oracle.com>; Rajesh Sivaramasubramaniom <rajesh.sivaramasubramaniom@oracle.com>; Gautham Ananthakrishna <gautham.ananthakrishna@oracle.com>
Subject: [PATCH V1 RFC 1/1] Subject: [[PATCH V1 RFC] 1/1] ocfs2: race between searching chunks and release journal_head from buffer_head
Encountered a race between ocfs2_test_bg_bit_allocatable() and
jbd2_journal_put_journal_head() resulting in the below vmcore.
PID: 106879 TASK: ffff880244ba9c00 CPU: 2 COMMAND: "loop3"
0 [ffff8802435ff1c0] panic at ffffffff816ed175
1 [ffff8802435ff240] oops_end at ffffffff8101a7c9
2 [ffff8802435ff270] no_context at ffffffff8106eccf
3 [ffff8802435ff2e0] __bad_area_nosemaphore at ffffffff8106ef9d
4 [ffff8802435ff330] bad_area_nosemaphore at ffffffff8106f143
5 [ffff8802435ff340] __do_page_fault at ffffffff8106f80b
6 [ffff8802435ff3a0] do_page_fault at ffffffff8106fc2f
7 [ffff8802435ff3e0] page_fault at ffffffff816fd667
[exception RIP: ocfs2_block_group_find_clear_bits+316]
RIP: ffffffffc11ef6fc RSP: ffff8802435ff498 RFLAGS: 00010206
RAX: 0000000000003918 RBX: 0000000000000001 RCX: 0000000000000018
RDX: 0000000000003918 RSI: 0000000000000000 RDI: ffff880060194040
RBP: ffff8802435ff4f8 R8: ffffffffff000000 R9: ffffffffffffffff
R10: ffff8802435ff730 R11: ffff8802a94e5800 R12: 0000000000000007
R13: 0000000000007e00 R14: 0000000000003918 R15: ffff88017c973a28
ORIG_RAX: ffffffffffffffff CS: e030 SS: e02b
8 [ffff8802435ff490] ocfs2_block_group_find_clear_bits at ffffffffc11ef680 [ocfs2]
9 [ffff8802435ff500] ocfs2_cluster_group_search at ffffffffc11ef916 [ocfs2]
10 [ffff8802435ff580] ocfs2_search_chain at ffffffffc11f0fb6 [ocfs2]
11 [ffff8802435ff660] ocfs2_claim_suballoc_bits at ffffffffc11f1b1b [ocfs2]
12 [ffff8802435ff6f0] __ocfs2_claim_clusters at ffffffffc11f32cb [ocfs2]
13 [ffff8802435ff770] ocfs2_claim_clusters at ffffffffc11f5caf [ocfs2]
14 [ffff8802435ff780] ocfs2_local_alloc_slide_window at ffffffffc11cc0db [ocfs2]
15 [ffff8802435ff820] ocfs2_reserve_local_alloc_bits at ffffffffc11ce53f [ocfs2]
16 [ffff8802435ff890] ocfs2_reserve_clusters_with_limit at ffffffffc11f59b5 [ocfs2]
17 [ffff8802435ff8e0] ocfs2_reserve_clusters at ffffffffc11f5c88 [ocfs2]
18 [ffff8802435ff8f0] ocfs2_lock_refcount_allocators at ffffffffc11dc169 [ocfs2]
19 [ffff8802435ff960] ocfs2_make_clusters_writable at ffffffffc11e4274 [ocfs2]
20 [ffff8802435ffa50] ocfs2_replace_cow at ffffffffc11e4df1 [ocfs2]
21 [ffff8802435ffac0] ocfs2_refcount_cow at ffffffffc11e54b1 [ocfs2]
22 [ffff8802435ffb80] ocfs2_file_write_iter at ffffffffc11bf8f4 [ocfs2]
23 [ffff8802435ffcd0] lo_rw_aio at ffffffff814a1b5d
24 [ffff8802435ffd80] loop_queue_work at ffffffff814a2802
25 [ffff8802435ffe60] kthread_worker_fn at ffffffff810a80d2
26 [ffff8802435ffec0] kthread at ffffffff810a7afb
27 [ffff8802435fff50] ret_from_fork at ffffffff816f7da1
When ocfs2_test_bg_bit_allocatable() called bh2jh(bg_bh), the bg_bh->b_private NULL as jbd2_journal_put_journal_head() raced and released the jounal head from the buffer head. Needed to take bit lock for the bit 'BH_JournalHead'
to fix this race.
Signed-off-by: Gautham Ananthakrishna <gautham.ananthakrishna@oracle.com>
---
fs/ocfs2/suballoc.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c index 8521942..86f33f2 100644
--- a/fs/ocfs2/suballoc.c
+++ b/fs/ocfs2/suballoc.c
@@ -1256,9 +1256,17 @@ static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh,
if (ocfs2_test_bit(nr, (unsigned long *)bg->bg_bitmap))
return 0;
+ /* Fast path */
if (!buffer_jbd(bg_bh))
return 1;
+ /* Slow path */
+ jbd_lock_bh_journal_head(bg_bh);
+ if (!buffer_jbd(bg_bh)){
+ jbd_unlock_bh_journal_head(bg_bh);
+ return 1;
+ }
+
jh = bh2jh(bg_bh);
spin_lock(&jh->b_state_lock);
bg = (struct ocfs2_group_desc *) jh->b_committed_data; @@ -1267,6 +1275,7 @@ static int ocfs2_test_bg_bit_allocatable(struct buffer_head *bg_bh,
else
ret = 1;
spin_unlock(&jh->b_state_lock);
+ jbd_unlock_bh_journal_head(bg_bh);
return ret;
}
--
1.8.3.1
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2021-10-20 5:15 [Ocfs2-devel] [PATCH V1 RFC 1/1] Subject: [[PATCH V1 RFC] 1/1] ocfs2: race between searching chunks and release journal_head from buffer_head Gautham Ananthakrishna
2021-10-20 5:15 ` [Ocfs2-devel] [PATCH V1 RFC " Gautham Ananthakrishna
2021-10-20 5:17 ` Gautham Ananthakrishna
2021-10-20 5:17 ` [Ocfs2-devel] [PATCH V1 RFC 1/1] Subject: [[PATCH V1 RFC] " Gautham Ananthakrishna
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