From 1cf89a8dee5e6e9d4fcb81b571a54d40068dfbb7 Mon Sep 17 00:00:00 2001
From: "Yan, Zheng" <zyan@redhat.com>
Date: Sat, 18 May 2019 11:18:44 +0800
Subject: ceph: single workqueue for inode related works

We have three workqueue for inode works. Later patch will introduce
one more work for inode. It's not good to introcuce more workqueue
and add more 'struct work_struct' to 'struct ceph_inode_info'.

Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
---
 fs/ceph/file.c  |   2 +-
 fs/ceph/inode.c | 124 +++++++++++++++++++++++++-------------------------------
 fs/ceph/super.c |  28 ++++---------
 fs/ceph/super.h |  17 ++++----
 4 files changed, 74 insertions(+), 97 deletions(-)

diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index 305daf043eb0..183c37c0a8fc 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -791,7 +791,7 @@ static void ceph_aio_complete_req(struct ceph_osd_request *req)
 		if (aio_work) {
 			INIT_WORK(&aio_work->work, ceph_aio_retry_work);
 			aio_work->req = req;
-			queue_work(ceph_inode_to_client(inode)->wb_wq,
+			queue_work(ceph_inode_to_client(inode)->inode_wq,
 				   &aio_work->work);
 			return;
 		}
diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index f85355bf49c4..3acdd3cc6039 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -33,9 +33,7 @@
 
 static const struct inode_operations ceph_symlink_iops;
 
-static void ceph_invalidate_work(struct work_struct *work);
-static void ceph_writeback_work(struct work_struct *work);
-static void ceph_vmtruncate_work(struct work_struct *work);
+static void ceph_inode_work(struct work_struct *work);
 
 /*
  * find or create an inode, given the ceph ino number
@@ -509,10 +507,8 @@ struct inode *ceph_alloc_inode(struct super_block *sb)
 	INIT_LIST_HEAD(&ci->i_snap_realm_item);
 	INIT_LIST_HEAD(&ci->i_snap_flush_item);
 
-	INIT_WORK(&ci->i_wb_work, ceph_writeback_work);
-	INIT_WORK(&ci->i_pg_inv_work, ceph_invalidate_work);
-
-	INIT_WORK(&ci->i_vmtruncate_work, ceph_vmtruncate_work);
+	INIT_WORK(&ci->i_work, ceph_inode_work);
+	ci->i_work_mask = 0;
 
 	ceph_fscache_inode_init(ci);
 
@@ -1746,51 +1742,62 @@ bool ceph_inode_set_size(struct inode *inode, loff_t size)
  */
 void ceph_queue_writeback(struct inode *inode)
 {
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	set_bit(CEPH_I_WORK_WRITEBACK, &ci->i_work_mask);
+
 	ihold(inode);
-	if (queue_work(ceph_inode_to_client(inode)->wb_wq,
-		       &ceph_inode(inode)->i_wb_work)) {
+	if (queue_work(ceph_inode_to_client(inode)->inode_wq,
+		       &ci->i_work)) {
 		dout("ceph_queue_writeback %p\n", inode);
 	} else {
-		dout("ceph_queue_writeback %p failed\n", inode);
+		dout("ceph_queue_writeback %p already queued, mask=%lx\n",
+		     inode, ci->i_work_mask);
 		iput(inode);
 	}
 }
 
-static void ceph_writeback_work(struct work_struct *work)
-{
-	struct ceph_inode_info *ci = container_of(work, struct ceph_inode_info,
-						  i_wb_work);
-	struct inode *inode = &ci->vfs_inode;
-
-	dout("writeback %p\n", inode);
-	filemap_fdatawrite(&inode->i_data);
-	iput(inode);
-}
-
 /*
  * queue an async invalidation
  */
 void ceph_queue_invalidate(struct inode *inode)
 {
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	set_bit(CEPH_I_WORK_INVALIDATE_PAGES, &ci->i_work_mask);
+
 	ihold(inode);
-	if (queue_work(ceph_inode_to_client(inode)->pg_inv_wq,
-		       &ceph_inode(inode)->i_pg_inv_work)) {
+	if (queue_work(ceph_inode_to_client(inode)->inode_wq,
+		       &ceph_inode(inode)->i_work)) {
 		dout("ceph_queue_invalidate %p\n", inode);
 	} else {
-		dout("ceph_queue_invalidate %p failed\n", inode);
+		dout("ceph_queue_invalidate %p already queued, mask=%lx\n",
+		     inode, ci->i_work_mask);
 		iput(inode);
 	}
 }
 
 /*
- * Invalidate inode pages in a worker thread.  (This can't be done
- * in the message handler context.)
+ * Queue an async vmtruncate.  If we fail to queue work, we will handle
+ * the truncation the next time we call __ceph_do_pending_vmtruncate.
  */
-static void ceph_invalidate_work(struct work_struct *work)
+void ceph_queue_vmtruncate(struct inode *inode)
 {
-	struct ceph_inode_info *ci = container_of(work, struct ceph_inode_info,
-						  i_pg_inv_work);
-	struct inode *inode = &ci->vfs_inode;
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	set_bit(CEPH_I_WORK_VMTRUNCATE, &ci->i_work_mask);
+
+	ihold(inode);
+	if (queue_work(ceph_inode_to_client(inode)->inode_wq,
+		       &ci->i_work)) {
+		dout("ceph_queue_vmtruncate %p\n", inode);
+	} else {
+		dout("ceph_queue_vmtruncate %p already queued, mask=%lx\n",
+		     inode, ci->i_work_mask);
+		iput(inode);
+	}
+}
+
+static void ceph_do_invalidate_pages(struct inode *inode)
+{
+	struct ceph_inode_info *ci = ceph_inode(inode);
 	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
 	u32 orig_gen;
 	int check = 0;
@@ -1842,44 +1849,6 @@ static void ceph_invalidate_work(struct work_struct *work)
 out:
 	if (check)
 		ceph_check_caps(ci, 0, NULL);
-	iput(inode);
-}
-
-
-/*
- * called by trunc_wq;
- *
- * We also truncate in a separate thread as well.
- */
-static void ceph_vmtruncate_work(struct work_struct *work)
-{
-	struct ceph_inode_info *ci = container_of(work, struct ceph_inode_info,
-						  i_vmtruncate_work);
-	struct inode *inode = &ci->vfs_inode;
-
-	dout("vmtruncate_work %p\n", inode);
-	__ceph_do_pending_vmtruncate(inode);
-	iput(inode);
-}
-
-/*
- * Queue an async vmtruncate.  If we fail to queue work, we will handle
- * the truncation the next time we call __ceph_do_pending_vmtruncate.
- */
-void ceph_queue_vmtruncate(struct inode *inode)
-{
-	struct ceph_inode_info *ci = ceph_inode(inode);
-
-	ihold(inode);
-
-	if (queue_work(ceph_sb_to_client(inode->i_sb)->trunc_wq,
-		       &ci->i_vmtruncate_work)) {
-		dout("ceph_queue_vmtruncate %p\n", inode);
-	} else {
-		dout("ceph_queue_vmtruncate %p failed, pending=%d\n",
-		     inode, ci->i_truncate_pending);
-		iput(inode);
-	}
 }
 
 /*
@@ -1943,6 +1912,25 @@ retry:
 	wake_up_all(&ci->i_cap_wq);
 }
 
+static void ceph_inode_work(struct work_struct *work)
+{
+	struct ceph_inode_info *ci = container_of(work, struct ceph_inode_info,
+						 i_work);
+	struct inode *inode = &ci->vfs_inode;
+
+	if (test_and_clear_bit(CEPH_I_WORK_WRITEBACK, &ci->i_work_mask)) {
+		dout("writeback %p\n", inode);
+		filemap_fdatawrite(&inode->i_data);
+	}
+	if (test_and_clear_bit(CEPH_I_WORK_INVALIDATE_PAGES, &ci->i_work_mask))
+		ceph_do_invalidate_pages(inode);
+
+	if (test_and_clear_bit(CEPH_I_WORK_VMTRUNCATE, &ci->i_work_mask))
+		__ceph_do_pending_vmtruncate(inode);
+
+	iput(inode);
+}
+
 /*
  * symlinks
  */
diff --git a/fs/ceph/super.c b/fs/ceph/super.c
index 01be7c1bc4c6..d57fa60dcd43 100644
--- a/fs/ceph/super.c
+++ b/fs/ceph/super.c
@@ -672,18 +672,12 @@ static struct ceph_fs_client *create_fs_client(struct ceph_mount_options *fsopt,
 	 * The number of concurrent works can be high but they don't need
 	 * to be processed in parallel, limit concurrency.
 	 */
-	fsc->wb_wq = alloc_workqueue("ceph-writeback", 0, 1);
-	if (!fsc->wb_wq)
+	fsc->inode_wq = alloc_workqueue("ceph-inode", WQ_UNBOUND, 0);
+	if (!fsc->inode_wq)
 		goto fail_client;
-	fsc->pg_inv_wq = alloc_workqueue("ceph-pg-invalid", 0, 1);
-	if (!fsc->pg_inv_wq)
-		goto fail_wb_wq;
-	fsc->trunc_wq = alloc_workqueue("ceph-trunc", 0, 1);
-	if (!fsc->trunc_wq)
-		goto fail_pg_inv_wq;
 	fsc->cap_wq = alloc_workqueue("ceph-cap", 0, 1);
 	if (!fsc->cap_wq)
-		goto fail_trunc_wq;
+		goto fail_inode_wq;
 
 	/* set up mempools */
 	err = -ENOMEM;
@@ -697,12 +691,8 @@ static struct ceph_fs_client *create_fs_client(struct ceph_mount_options *fsopt,
 
 fail_cap_wq:
 	destroy_workqueue(fsc->cap_wq);
-fail_trunc_wq:
-	destroy_workqueue(fsc->trunc_wq);
-fail_pg_inv_wq:
-	destroy_workqueue(fsc->pg_inv_wq);
-fail_wb_wq:
-	destroy_workqueue(fsc->wb_wq);
+fail_inode_wq:
+	destroy_workqueue(fsc->inode_wq);
 fail_client:
 	ceph_destroy_client(fsc->client);
 fail:
@@ -715,9 +705,7 @@ fail:
 
 static void flush_fs_workqueues(struct ceph_fs_client *fsc)
 {
-	flush_workqueue(fsc->wb_wq);
-	flush_workqueue(fsc->pg_inv_wq);
-	flush_workqueue(fsc->trunc_wq);
+	flush_workqueue(fsc->inode_wq);
 	flush_workqueue(fsc->cap_wq);
 }
 
@@ -725,9 +713,7 @@ static void destroy_fs_client(struct ceph_fs_client *fsc)
 {
 	dout("destroy_fs_client %p\n", fsc);
 
-	destroy_workqueue(fsc->wb_wq);
-	destroy_workqueue(fsc->pg_inv_wq);
-	destroy_workqueue(fsc->trunc_wq);
+	destroy_workqueue(fsc->inode_wq);
 	destroy_workqueue(fsc->cap_wq);
 
 	mempool_destroy(fsc->wb_pagevec_pool);
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index 6edab9a750f8..3fb866a979ce 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -109,9 +109,7 @@ struct ceph_fs_client {
 	mempool_t *wb_pagevec_pool;
 	atomic_long_t writeback_count;
 
-	struct workqueue_struct *wb_wq;
-	struct workqueue_struct *pg_inv_wq;
-	struct workqueue_struct *trunc_wq;
+	struct workqueue_struct *inode_wq;
 	struct workqueue_struct *cap_wq;
 
 #ifdef CONFIG_DEBUG_FS
@@ -387,10 +385,8 @@ struct ceph_inode_info {
 	struct list_head i_snap_realm_item;
 	struct list_head i_snap_flush_item;
 
-	struct work_struct i_wb_work;  /* writeback work */
-	struct work_struct i_pg_inv_work;  /* page invalidation work */
-
-	struct work_struct i_vmtruncate_work;
+	struct work_struct i_work;
+	unsigned long  i_work_mask;
 
 #ifdef CONFIG_CEPH_FSCACHE
 	struct fscache_cookie *fscache;
@@ -512,6 +508,13 @@ static inline struct inode *ceph_find_inode(struct super_block *sb,
 #define CEPH_I_ERROR_FILELOCK	(1 << 12) /* have seen file lock errors */
 
 
+/*
+ * Masks of ceph inode work.
+ */
+#define CEPH_I_WORK_WRITEBACK		0 /* writeback */
+#define CEPH_I_WORK_INVALIDATE_PAGES	1 /* invalidate pages */
+#define CEPH_I_WORK_VMTRUNCATE		2 /* vmtruncate */
+
 /*
  * We set the ERROR_WRITE bit when we start seeing write errors on an inode
  * and then clear it when they start succeeding. Note that we do a lockless
-- 
cgit v1.2.3-70-g09d2


From 3e1d0452edceebb903d23db53201013c940bf000 Mon Sep 17 00:00:00 2001
From: "Yan, Zheng" <zyan@redhat.com>
Date: Sat, 18 May 2019 20:39:55 +0800
Subject: ceph: avoid iput_final() while holding mutex or in dispatch thread

iput_final() may wait for reahahead pages. The wait can cause deadlock.
For example:

  Workqueue: ceph-msgr ceph_con_workfn [libceph]
    Call Trace:
     schedule+0x36/0x80
     io_schedule+0x16/0x40
     __lock_page+0x101/0x140
     truncate_inode_pages_range+0x556/0x9f0
     truncate_inode_pages_final+0x4d/0x60
     evict+0x182/0x1a0
     iput+0x1d2/0x220
     iterate_session_caps+0x82/0x230 [ceph]
     dispatch+0x678/0xa80 [ceph]
     ceph_con_workfn+0x95b/0x1560 [libceph]
     process_one_work+0x14d/0x410
     worker_thread+0x4b/0x460
     kthread+0x105/0x140
     ret_from_fork+0x22/0x40

  Workqueue: ceph-msgr ceph_con_workfn [libceph]
    Call Trace:
     __schedule+0x3d6/0x8b0
     schedule+0x36/0x80
     schedule_preempt_disabled+0xe/0x10
     mutex_lock+0x2f/0x40
     ceph_check_caps+0x505/0xa80 [ceph]
     ceph_put_wrbuffer_cap_refs+0x1e5/0x2c0 [ceph]
     writepages_finish+0x2d3/0x410 [ceph]
     __complete_request+0x26/0x60 [libceph]
     handle_reply+0x6c8/0xa10 [libceph]
     dispatch+0x29a/0xbb0 [libceph]
     ceph_con_workfn+0x95b/0x1560 [libceph]
     process_one_work+0x14d/0x410
     worker_thread+0x4b/0x460
     kthread+0x105/0x140
     ret_from_fork+0x22/0x40

In above example, truncate_inode_pages_range() waits for readahead pages
while holding s_mutex. ceph_check_caps() waits for s_mutex and blocks
OSD dispatch thread. Later OSD replies (for readahead) can't be handled.

ceph_check_caps() also may lock snap_rwsem for read. So similar deadlock
can happen if iput_final() is called while holding snap_rwsem.

In general, it's not good to call iput_final() inside MDS/OSD dispatch
threads or while holding any mutex.

The fix is introducing ceph_async_iput(), which calls iput_final() in
workqueue.

Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
---
 fs/ceph/caps.c       | 12 ++++++++----
 fs/ceph/inode.c      | 31 +++++++++++++++++++++++++++----
 fs/ceph/mds_client.c | 28 ++++++++++++++++++----------
 fs/ceph/quota.c      |  9 ++++++---
 fs/ceph/snap.c       | 16 +++++++++++-----
 fs/ceph/super.h      |  2 +-
 6 files changed, 71 insertions(+), 27 deletions(-)

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 72f8e1311392..52a2b90621cd 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -2992,8 +2992,10 @@ void ceph_put_wrbuffer_cap_refs(struct ceph_inode_info *ci, int nr,
 	}
 	if (complete_capsnap)
 		wake_up_all(&ci->i_cap_wq);
-	while (put-- > 0)
-		iput(inode);
+	while (put-- > 0) {
+		/* avoid calling iput_final() in osd dispatch threads */
+		ceph_async_iput(inode);
+	}
 }
 
 /*
@@ -3964,8 +3966,9 @@ void ceph_handle_caps(struct ceph_mds_session *session,
 done:
 	mutex_unlock(&session->s_mutex);
 done_unlocked:
-	iput(inode);
 	ceph_put_string(extra_info.pool_ns);
+	/* avoid calling iput_final() in mds dispatch threads */
+	ceph_async_iput(inode);
 	return;
 
 flush_cap_releases:
@@ -4011,7 +4014,8 @@ void ceph_check_delayed_caps(struct ceph_mds_client *mdsc)
 		if (inode) {
 			dout("check_delayed_caps on %p\n", inode);
 			ceph_check_caps(ci, flags, NULL);
-			iput(inode);
+			/* avoid calling iput_final() in tick thread */
+			ceph_async_iput(inode);
 		}
 	}
 	spin_unlock(&mdsc->cap_delay_lock);
diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
index 3acdd3cc6039..761451f36e2d 100644
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -1476,7 +1476,8 @@ static int readdir_prepopulate_inodes_only(struct ceph_mds_request *req,
 			pr_err("fill_inode badness on %p got %d\n", in, rc);
 			err = rc;
 		}
-		iput(in);
+		/* avoid calling iput_final() in mds dispatch threads */
+		ceph_async_iput(in);
 	}
 
 	return err;
@@ -1674,8 +1675,11 @@ retry_lookup:
 				 &req->r_caps_reservation);
 		if (ret < 0) {
 			pr_err("fill_inode badness on %p\n", in);
-			if (d_really_is_negative(dn))
-				iput(in);
+			if (d_really_is_negative(dn)) {
+				/* avoid calling iput_final() in mds
+				 * dispatch threads */
+				ceph_async_iput(in);
+			}
 			d_drop(dn);
 			err = ret;
 			goto next_item;
@@ -1685,7 +1689,7 @@ retry_lookup:
 			if (ceph_security_xattr_deadlock(in)) {
 				dout(" skip splicing dn %p to inode %p"
 				     " (security xattr deadlock)\n", dn, in);
-				iput(in);
+				ceph_async_iput(in);
 				skipped++;
 				goto next_item;
 			}
@@ -1736,6 +1740,25 @@ bool ceph_inode_set_size(struct inode *inode, loff_t size)
 	return ret;
 }
 
+/*
+ * Put reference to inode, but avoid calling iput_final() in current thread.
+ * iput_final() may wait for reahahead pages. The wait can cause deadlock in
+ * some contexts.
+ */
+void ceph_async_iput(struct inode *inode)
+{
+	if (!inode)
+		return;
+	for (;;) {
+		if (atomic_add_unless(&inode->i_count, -1, 1))
+			break;
+		if (queue_work(ceph_inode_to_client(inode)->inode_wq,
+			       &ceph_inode(inode)->i_work))
+			break;
+		/* queue work failed, i_count must be at least 2 */
+	}
+}
+
 /*
  * Write back inode data in a worker thread.  (This can't be done
  * in the message handler context.)
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 959b1bf7c327..6af2d0d4a87a 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -690,11 +690,12 @@ void ceph_mdsc_release_request(struct kref *kref)
 		ceph_msg_put(req->r_reply);
 	if (req->r_inode) {
 		ceph_put_cap_refs(ceph_inode(req->r_inode), CEPH_CAP_PIN);
-		iput(req->r_inode);
+		/* avoid calling iput_final() in mds dispatch threads */
+		ceph_async_iput(req->r_inode);
 	}
 	if (req->r_parent)
 		ceph_put_cap_refs(ceph_inode(req->r_parent), CEPH_CAP_PIN);
-	iput(req->r_target_inode);
+	ceph_async_iput(req->r_target_inode);
 	if (req->r_dentry)
 		dput(req->r_dentry);
 	if (req->r_old_dentry)
@@ -708,7 +709,7 @@ void ceph_mdsc_release_request(struct kref *kref)
 		 */
 		ceph_put_cap_refs(ceph_inode(req->r_old_dentry_dir),
 				  CEPH_CAP_PIN);
-		iput(req->r_old_dentry_dir);
+		ceph_async_iput(req->r_old_dentry_dir);
 	}
 	kfree(req->r_path1);
 	kfree(req->r_path2);
@@ -818,7 +819,8 @@ static void __unregister_request(struct ceph_mds_client *mdsc,
 	}
 
 	if (req->r_unsafe_dir) {
-		iput(req->r_unsafe_dir);
+		/* avoid calling iput_final() in mds dispatch threads */
+		ceph_async_iput(req->r_unsafe_dir);
 		req->r_unsafe_dir = NULL;
 	}
 
@@ -983,7 +985,7 @@ static int __choose_mds(struct ceph_mds_client *mdsc,
 		cap = rb_entry(rb_first(&ci->i_caps), struct ceph_cap, ci_node);
 	if (!cap) {
 		spin_unlock(&ci->i_ceph_lock);
-		iput(inode);
+		ceph_async_iput(inode);
 		goto random;
 	}
 	mds = cap->session->s_mds;
@@ -992,7 +994,9 @@ static int __choose_mds(struct ceph_mds_client *mdsc,
 	     cap == ci->i_auth_cap ? "auth " : "", cap);
 	spin_unlock(&ci->i_ceph_lock);
 out:
-	iput(inode);
+	/* avoid calling iput_final() while holding mdsc->mutex or
+	 * in mds dispatch threads */
+	ceph_async_iput(inode);
 	return mds;
 
 random:
@@ -1302,7 +1306,9 @@ int ceph_iterate_session_caps(struct ceph_mds_session *session,
 		spin_unlock(&session->s_cap_lock);
 
 		if (last_inode) {
-			iput(last_inode);
+			/* avoid calling iput_final() while holding
+			 * s_mutex or in mds dispatch threads */
+			ceph_async_iput(last_inode);
 			last_inode = NULL;
 		}
 		if (old_cap) {
@@ -1335,7 +1341,7 @@ out:
 	session->s_cap_iterator = NULL;
 	spin_unlock(&session->s_cap_lock);
 
-	iput(last_inode);
+	ceph_async_iput(last_inode);
 	if (old_cap)
 		ceph_put_cap(session->s_mdsc, old_cap);
 
@@ -1471,7 +1477,8 @@ static void remove_session_caps(struct ceph_mds_session *session)
 			spin_unlock(&session->s_cap_lock);
 
 			inode = ceph_find_inode(sb, vino);
-			iput(inode);
+			 /* avoid calling iput_final() while holding s_mutex */
+			ceph_async_iput(inode);
 
 			spin_lock(&session->s_cap_lock);
 		}
@@ -3912,8 +3919,9 @@ release:
 	ceph_con_send(&session->s_con, msg);
 
 out:
-	iput(inode);
 	mutex_unlock(&session->s_mutex);
+	/* avoid calling iput_final() in mds dispatch threads */
+	ceph_async_iput(inode);
 	return;
 
 bad:
diff --git a/fs/ceph/quota.c b/fs/ceph/quota.c
index c4522212872c..d629fc857450 100644
--- a/fs/ceph/quota.c
+++ b/fs/ceph/quota.c
@@ -74,7 +74,8 @@ void ceph_handle_quota(struct ceph_mds_client *mdsc,
 		            le64_to_cpu(h->max_files));
 	spin_unlock(&ci->i_ceph_lock);
 
-	iput(inode);
+	/* avoid calling iput_final() in dispatch thread */
+	ceph_async_iput(inode);
 }
 
 static struct ceph_quotarealm_inode *
@@ -235,7 +236,8 @@ restart:
 
 		ci = ceph_inode(in);
 		has_quota = __ceph_has_any_quota(ci);
-		iput(in);
+		/* avoid calling iput_final() while holding mdsc->snap_rwsem */
+		ceph_async_iput(in);
 
 		next = realm->parent;
 		if (has_quota || !next)
@@ -372,7 +374,8 @@ restart:
 			pr_warn("Invalid quota check op (%d)\n", op);
 			exceeded = true; /* Just break the loop */
 		}
-		iput(in);
+		/* avoid calling iput_final() while holding mdsc->snap_rwsem */
+		ceph_async_iput(in);
 
 		next = realm->parent;
 		if (exceeded || !next)
diff --git a/fs/ceph/snap.c b/fs/ceph/snap.c
index b26e12cd8ec3..72c6c022f02b 100644
--- a/fs/ceph/snap.c
+++ b/fs/ceph/snap.c
@@ -648,13 +648,15 @@ static void queue_realm_cap_snaps(struct ceph_snap_realm *realm)
 		if (!inode)
 			continue;
 		spin_unlock(&realm->inodes_with_caps_lock);
-		iput(lastinode);
+		/* avoid calling iput_final() while holding
+		 * mdsc->snap_rwsem or in mds dispatch threads */
+		ceph_async_iput(lastinode);
 		lastinode = inode;
 		ceph_queue_cap_snap(ci);
 		spin_lock(&realm->inodes_with_caps_lock);
 	}
 	spin_unlock(&realm->inodes_with_caps_lock);
-	iput(lastinode);
+	ceph_async_iput(lastinode);
 
 	dout("queue_realm_cap_snaps %p %llx done\n", realm, realm->ino);
 }
@@ -806,7 +808,9 @@ static void flush_snaps(struct ceph_mds_client *mdsc)
 		ihold(inode);
 		spin_unlock(&mdsc->snap_flush_lock);
 		ceph_flush_snaps(ci, &session);
-		iput(inode);
+		/* avoid calling iput_final() while holding
+		 * session->s_mutex or in mds dispatch threads */
+		ceph_async_iput(inode);
 		spin_lock(&mdsc->snap_flush_lock);
 	}
 	spin_unlock(&mdsc->snap_flush_lock);
@@ -950,12 +954,14 @@ void ceph_handle_snap(struct ceph_mds_client *mdsc,
 			ceph_get_snap_realm(mdsc, realm);
 			ceph_put_snap_realm(mdsc, oldrealm);
 
-			iput(inode);
+			/* avoid calling iput_final() while holding
+			 * mdsc->snap_rwsem or mds in dispatch threads */
+			ceph_async_iput(inode);
 			continue;
 
 skip_inode:
 			spin_unlock(&ci->i_ceph_lock);
-			iput(inode);
+			ceph_async_iput(inode);
 		}
 
 		/* we may have taken some of the old realm's children. */
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index 3fb866a979ce..5f27e1f7f2d6 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -899,9 +899,9 @@ extern int ceph_inode_holds_cap(struct inode *inode, int mask);
 extern bool ceph_inode_set_size(struct inode *inode, loff_t size);
 extern void __ceph_do_pending_vmtruncate(struct inode *inode);
 extern void ceph_queue_vmtruncate(struct inode *inode);
-
 extern void ceph_queue_invalidate(struct inode *inode);
 extern void ceph_queue_writeback(struct inode *inode);
+extern void ceph_async_iput(struct inode *inode);
 
 extern int __ceph_do_getattr(struct inode *inode, struct page *locked_page,
 			     int mask, bool force);
-- 
cgit v1.2.3-70-g09d2


From 7b2f936fc8282ab56d4d21247f2f9c21607c085c Mon Sep 17 00:00:00 2001
From: "Yan, Zheng" <zyan@redhat.com>
Date: Mon, 20 May 2019 09:50:09 +0800
Subject: ceph: fix error handling in ceph_get_caps()

The function return 0 even when interrupted or try_get_cap_refs()
return error.

Fixes: 1199d7da2d ("ceph: simplify arguments and return semantics of try_get_cap_refs")
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
---
 fs/ceph/caps.c | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index 52a2b90621cd..0176241eaea7 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -2738,15 +2738,13 @@ int ceph_get_caps(struct ceph_inode_info *ci, int need, int want,
 		_got = 0;
 		ret = try_get_cap_refs(ci, need, want, endoff,
 				       false, &_got);
-		if (ret == -EAGAIN) {
+		if (ret == -EAGAIN)
 			continue;
-		} else if (!ret) {
-			int err;
-
+		if (!ret) {
 			DEFINE_WAIT_FUNC(wait, woken_wake_function);
 			add_wait_queue(&ci->i_cap_wq, &wait);
 
-			while (!(err = try_get_cap_refs(ci, need, want, endoff,
+			while (!(ret = try_get_cap_refs(ci, need, want, endoff,
 							true, &_got))) {
 				if (signal_pending(current)) {
 					ret = -ERESTARTSYS;
@@ -2756,14 +2754,16 @@ int ceph_get_caps(struct ceph_inode_info *ci, int need, int want,
 			}
 
 			remove_wait_queue(&ci->i_cap_wq, &wait);
-			if (err == -EAGAIN)
+			if (ret == -EAGAIN)
 				continue;
 		}
-		if (ret == -ESTALE) {
-			/* session was killed, try renew caps */
-			ret = ceph_renew_caps(&ci->vfs_inode);
-			if (ret == 0)
-				continue;
+		if (ret < 0) {
+			if (ret == -ESTALE) {
+				/* session was killed, try renew caps */
+				ret = ceph_renew_caps(&ci->vfs_inode);
+				if (ret == 0)
+					continue;
+			}
 			return ret;
 		}
 
-- 
cgit v1.2.3-70-g09d2