From: Wengang Wang wen.gang.wang@oracle.com
commit 90bd070aae6c4fb5d302f9c4b9c88be60c8197ec upstream.
The following deadlock is detected:
truncate -> setattr path is waiting for pending direct IO to be done (inode->i_dio_count become zero) with inode->i_rwsem held (down_write).
PID: 14827 TASK: ffff881686a9af80 CPU: 20 COMMAND: "ora_p005_hrltd9" #0 __schedule at ffffffff818667cc #1 schedule at ffffffff81866de6 #2 inode_dio_wait at ffffffff812a2d04 #3 ocfs2_setattr at ffffffffc05f322e [ocfs2] #4 notify_change at ffffffff812a5a09 #5 do_truncate at ffffffff812808f5 #6 do_sys_ftruncate.constprop.18 at ffffffff81280cf2 #7 sys_ftruncate at ffffffff81280d8e #8 do_syscall_64 at ffffffff81003949 #9 entry_SYSCALL_64_after_hwframe at ffffffff81a001ad
dio completion path is going to complete one direct IO (decrement inode->i_dio_count), but before that it hung at locking inode->i_rwsem:
#0 __schedule+700 at ffffffff818667cc #1 schedule+54 at ffffffff81866de6 #2 rwsem_down_write_failed+536 at ffffffff8186aa28 #3 call_rwsem_down_write_failed+23 at ffffffff8185a1b7 #4 down_write+45 at ffffffff81869c9d #5 ocfs2_dio_end_io_write+180 at ffffffffc05d5444 [ocfs2] #6 ocfs2_dio_end_io+85 at ffffffffc05d5a85 [ocfs2] #7 dio_complete+140 at ffffffff812c873c #8 dio_aio_complete_work+25 at ffffffff812c89f9 #9 process_one_work+361 at ffffffff810b1889 #10 worker_thread+77 at ffffffff810b233d #11 kthread+261 at ffffffff810b7fd5 #12 ret_from_fork+62 at ffffffff81a0035e
Thus above forms ABBA deadlock. The same deadlock was mentioned in upstream commit 28f5a8a7c033 ("ocfs2: should wait dio before inode lock in ocfs2_setattr()"). It seems that that commit only removed the cluster lock (the victim of above dead lock) from the ABBA deadlock party.
End-user visible effects: Process hang in truncate -> ocfs2_setattr path and other processes hang at ocfs2_dio_end_io_write path.
This is to fix the deadlock itself. It removes inode_lock() call from dio completion path to remove the deadlock and add ip_alloc_sem lock in setattr path to synchronize the inode modifications.
[wen.gang.wang@oracle.com: remove the "had_alloc_lock" as suggested] Link: https://lkml.kernel.org/r/20210402171344.1605-1-wen.gang.wang@oracle.com
Link: https://lkml.kernel.org/r/20210331203654.3911-1-wen.gang.wang@oracle.com Signed-off-by: Wengang Wang wen.gang.wang@oracle.com Reviewed-by: Joseph Qi joseph.qi@linux.alibaba.com Cc: Mark Fasheh mark@fasheh.com Cc: Joel Becker jlbec@evilplan.org Cc: Junxiao Bi junxiao.bi@oracle.com Cc: Changwei Ge gechangwei@live.cn Cc: Gang He ghe@suse.com Cc: Jun Piao piaojun@huawei.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ocfs2/aops.c | 11 +---------- fs/ocfs2/file.c | 8 ++++++-- 2 files changed, 7 insertions(+), 12 deletions(-)
--- a/fs/ocfs2/aops.c +++ b/fs/ocfs2/aops.c @@ -2301,7 +2301,7 @@ static void ocfs2_dio_end_io_write(struc struct ocfs2_alloc_context *meta_ac = NULL; handle_t *handle = NULL; loff_t end = offset + bytes; - int ret = 0, credits = 0, locked = 0; + int ret = 0, credits = 0;
ocfs2_init_dealloc_ctxt(&dealloc);
@@ -2312,13 +2312,6 @@ static void ocfs2_dio_end_io_write(struc !dwc->dw_orphaned) goto out;
- /* ocfs2_file_write_iter will get i_mutex, so we need not lock if we - * are in that context. */ - if (dwc->dw_writer_pid != task_pid_nr(current)) { - inode_lock(inode); - locked = 1; - } - ret = ocfs2_inode_lock(inode, &di_bh, 1); if (ret < 0) { mlog_errno(ret); @@ -2393,8 +2386,6 @@ out: if (meta_ac) ocfs2_free_alloc_context(meta_ac); ocfs2_run_deallocs(osb, &dealloc); - if (locked) - inode_unlock(inode); ocfs2_dio_free_write_ctx(inode, dwc); }
--- a/fs/ocfs2/file.c +++ b/fs/ocfs2/file.c @@ -1236,22 +1236,24 @@ int ocfs2_setattr(struct dentry *dentry, goto bail_unlock; } } + down_write(&OCFS2_I(inode)->ip_alloc_sem); handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS + 2 * ocfs2_quota_trans_credits(sb)); if (IS_ERR(handle)) { status = PTR_ERR(handle); mlog_errno(status); - goto bail_unlock; + goto bail_unlock_alloc; } status = __dquot_transfer(inode, transfer_to); if (status < 0) goto bail_commit; } else { + down_write(&OCFS2_I(inode)->ip_alloc_sem); handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS); if (IS_ERR(handle)) { status = PTR_ERR(handle); mlog_errno(status); - goto bail_unlock; + goto bail_unlock_alloc; } }
@@ -1264,6 +1266,8 @@ int ocfs2_setattr(struct dentry *dentry,
bail_commit: ocfs2_commit_trans(osb, handle); +bail_unlock_alloc: + up_write(&OCFS2_I(inode)->ip_alloc_sem); bail_unlock: if (status) { ocfs2_inode_unlock(inode, 1);