Unregister and reregister BDI devices in the proper order. This patch
avoids that the following kernel warning can be triggered during
SCSI device reregistration:
WARNING: CPU: 7 PID: 203 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x68/0x80()
sysfs: cannot create duplicate filename '/devices/virtual/bdi/8:32'
Workqueue: events_unbound async_run_entry_fn
Call Trace:
[<ffffffff814ff5a4>] dump_stack+0x4c/0x65
[<ffffffff810746ba>] warn_slowpath_common+0x8a/0xc0
[<ffffffff81074736>] warn_slowpath_fmt+0x46/0x50
[<ffffffff81237ca8>] sysfs_warn_dup+0x68/0x80
[<ffffffff81237d8e>] sysfs_create_dir_ns+0x7e/0x90
[<ffffffff81291f58>] kobject_add_internal+0xa8/0x320
[<ffffffff812923a0>] kobject_add+0x60/0xb0
[<ffffffff8138c937>] device_add+0x107/0x5e0
[<ffffffff8138d018>] device_create_groups_vargs+0xd8/0x100
[<ffffffff8138d05c>] device_create_vargs+0x1c/0x20
[<ffffffff8117f233>] bdi_register+0x63/0x2a0
[<ffffffff8117f497>] bdi_register_dev+0x27/0x30
[<ffffffff81281549>] add_disk+0x1a9/0x4e0
[<ffffffffa00c5739>] sd_probe_async+0x119/0x1d0 [sd_mod]
[<ffffffff8109a81a>] async_run_entry_fn+0x4a/0x140
[<ffffffff81091078>] process_one_work+0x1d8/0x7c0
[<ffffffff81091774>] worker_thread+0x114/0x460
[<ffffffff81097878>] kthread+0xf8/0x110
[<ffffffff8150801f>] ret_from_fork+0x3f/0x70
Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxx>
Cc: Aaro Koskinen <aaro.koskinen@xxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
---
drivers/scsi/scsi_sysfs.c | 2 ++
include/linux/backing-dev-defs.h | 1 +
include/linux/backing-dev.h | 1 +
mm/backing-dev.c | 28 ++++++++++++++++++++++++++--
4 files changed, 30 insertions(+), 2 deletions(-)
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index f5ace2b..8d64518 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -12,6 +12,7 @@
#include <linux/blkdev.h>
#include <linux/device.h>
#include <linux/pm_runtime.h>
+#include <linux/backing-dev.h>
#include <scsi/scsi.h>
#include <scsi/scsi_device.h>
@@ -1110,6 +1111,7 @@ void __scsi_remove_device(struct scsi_device *sdev)
device_unregister(&sdev->sdev_dev);
transport_remove_device(dev);
scsi_dh_remove_device(sdev);
+ bdi_sysfs_del(&sdev->request_queue->backing_dev_info);
device_del(dev);
} else
put_device(&sdev->sdev_dev);
diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h
index 1b4d69f..1a42ecb 100644
--- a/include/linux/backing-dev-defs.h
+++ b/include/linux/backing-dev-defs.h
@@ -135,6 +135,7 @@ struct bdi_writeback {
struct backing_dev_info {
struct list_head bdi_list;
+ bool is_visible;
unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
unsigned int capabilities; /* Device capabilities */
congested_fn *congested_fn; /* Function pointer if device is md/dm */
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index c82794f..9004d90 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -24,6 +24,7 @@ __printf(3, 4)
int bdi_register(struct backing_dev_info *bdi, struct device *parent,
const char *fmt, ...);
int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
+void bdi_sysfs_del(struct backing_dev_info *bdi);
void bdi_unregister(struct backing_dev_info *bdi);
int __must_check bdi_setup_and_register(struct backing_dev_info *, char *);
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 8ed2ffd..b56971f 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -774,6 +774,7 @@ int bdi_init(struct backing_dev_info *bdi)
int ret;
bdi->dev = NULL;
+ bdi->is_visible = false;
bdi->min_ratio = 0;
bdi->max_ratio = 100;
@@ -806,6 +807,7 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent,
return PTR_ERR(dev);
bdi->dev = dev;
+ bdi->is_visible = true;
bdi_debug_register(bdi, dev_name(dev));
set_bit(WB_registered, &bdi->wb.state);
@@ -837,6 +839,28 @@ static void bdi_remove_from_list(struct backing_dev_info *bdi)
synchronize_rcu_expedited();
}
+/**
+ * bdi_sysfs_del - remove a BDI device from sysfs
+ * @bdi: BDI device pointer.
+ *
+ * It is safe to call this function more than once.
+ */
+void bdi_sysfs_del(struct backing_dev_info *bdi)
+{
+ bool is_visible = false;
+
+ spin_lock_bh(&bdi_lock);
+ swap(bdi->is_visible, is_visible);
+ spin_unlock_bh(&bdi_lock);
+
+ if (!is_visible)
+ return;
+
+ bdi_debug_unregister(bdi);
+ device_del(bdi->dev);
+}
+EXPORT_SYMBOL(bdi_sysfs_del);
+
void bdi_unregister(struct backing_dev_info *bdi)
{
/* make sure nobody finds us on the bdi_list anymore */
@@ -845,8 +869,8 @@ void bdi_unregister(struct backing_dev_info *bdi)
cgwb_bdi_destroy(bdi);
if (bdi->dev) {
- bdi_debug_unregister(bdi);
- device_unregister(bdi->dev);
+ bdi_sysfs_del(bdi);
+ put_device(bdi->dev);
bdi->dev = NULL;
}
}
--
2.1.4
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