[Devel] [PATCH vz7 v2] ploop: increase logging on errors when opening new deltas

[Alexander Atanasov]

Ocassionally we got EBUSY but it is a bit over used,
so it is not clear what it means.

Add more logging to catch the source of the error.

https://jira.vzint.dev/browse/PSBM-146836
Signed-off-by: Alexander Atanasov <alexander.atanasov at virtuozzo.com>
---
 drivers/block/ploop/dev.c         |  9 ++++++++-
 drivers/block/ploop/fmt_ploop1.c  |  4 +++-
 drivers/block/ploop/io_kaio.c     | 13 ++++++++++---
 drivers/block/ploop/io_kaio_map.c |  7 +++++--
 4 files changed, 26 insertions(+), 7 deletions(-)

v1->v2: addressing review comments - print the error value and fix coding style

diff --git a/drivers/block/ploop/dev.c b/drivers/block/ploop/dev.c
index 2833865b087f..8e238eafd9f2 100644
--- a/drivers/block/ploop/dev.c
+++ b/drivers/block/ploop/dev.c
@@ -3582,8 +3582,11 @@ static int ploop_replace_delta(struct ploop_device * plo, unsigned long arg)
 			   sizeof(struct ploop_ctl_chunk)))
 		return -EFAULT;
 
-	if (plo->maintenance_type != PLOOP_MNTN_OFF)
+	if (plo->maintenance_type != PLOOP_MNTN_OFF) {
+		if (printk_ratelimit())
+			PL_WARN(plo, "Attempt to replace while in maintenance mode\n");
 		return -EBUSY;
+	}
 
 	old_delta = find_delta(plo, ctl.pctl_level);
 	if (old_delta == NULL)
@@ -3596,6 +3599,10 @@ static int ploop_replace_delta(struct ploop_device * plo, unsigned long arg)
 	if (IS_ERR(delta))
 		return PTR_ERR(delta);
 
+	WARN_ONCE(delta->ops != old_delta->ops,
+		  "New delta uses different io %p vs %p\n",
+		  delta->ops, old_delta->ops);
+
 	err = delta->ops->compose(delta, 1, &chunk);
 	if (err)
 		goto out_destroy;
diff --git a/drivers/block/ploop/fmt_ploop1.c b/drivers/block/ploop/fmt_ploop1.c
index e59a9eb50ac2..a0369db35c83 100644
--- a/drivers/block/ploop/fmt_ploop1.c
+++ b/drivers/block/ploop/fmt_ploop1.c
@@ -314,8 +314,10 @@ ploop1_open(struct ploop_delta * delta)
 	if (!(delta->flags & PLOOP_FMT_RDONLY)) {
 		pvd_header_set_disk_in_use(vh);
 		err = delta->io.ops->sync_write(&delta->io, ph->dyn_page, 4096, 0, 0);
-		if (err)
+		if (err) {
+			PL_ERR(delta->plo, "failed to update in use err=%d\n", err);
 			goto out_err;
+		}
 	}
 
 	delta->io.alloc_head = ph->alloc_head;
diff --git a/drivers/block/ploop/io_kaio.c b/drivers/block/ploop/io_kaio.c
index 35c0fad43baf..098f6c7b5f2d 100644
--- a/drivers/block/ploop/io_kaio.c
+++ b/drivers/block/ploop/io_kaio.c
@@ -966,17 +966,23 @@ static int kaio_open(struct ploop_io * io)
 	io->files.bdev = io->files.inode->i_sb->s_bdev;
 
 	err = io->ops->sync(io);
-	if (err)
+	if (err) {
+		PL_WARN(delta->plo, "open failed to sync err=%d\n", err);
 		return err;
+	}
 
 	mutex_lock(&io->files.inode->i_mutex);
 	err = kaio_invalidate_cache(io);
-	if (!err)
+	if (err)
+		PL_WARN(delta->plo, "invaldiate_cache failed err=%d\n", err);
+	else
 		err = ploop_kaio_open(file, delta->flags & PLOOP_FMT_RDONLY);
 	mutex_unlock(&io->files.inode->i_mutex);
 
-	if (err)
+	if (err) {
+		PL_WARN(delta->plo, "open failed err=%d\n", err);
 		return err;
+	}
 
 	io->files.em_tree = &dummy_em_tree;
 
@@ -988,6 +994,7 @@ static int kaio_open(struct ploop_io * io)
 			err = PTR_ERR(io->fsync_thread);
 			io->fsync_thread = NULL;
 			ploop_kaio_close(io->files.mapping, 0);
+			PL_WARN(delta->plo, "fsync thread start failed=%d\n", err);
 			return err;
 		}
 
diff --git a/drivers/block/ploop/io_kaio_map.c b/drivers/block/ploop/io_kaio_map.c
index d4ff39d95e74..59e35c562ef9 100644
--- a/drivers/block/ploop/io_kaio_map.c
+++ b/drivers/block/ploop/io_kaio_map.c
@@ -35,10 +35,13 @@ int ploop_kaio_open(struct file * file, int rdonly)
 				else
 					m->readers++;
 			} else {
-				if (m->readers)
+				if (m->readers) {
+					pr_warn("File is already active:%d\n",
+						m->readers);
 					err = -EBUSY;
-				else
+				} else {
 					m->readers = -1;
+				}
 			}
 			goto kaio_open_done;
 		}
-- 
2.39.1