diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 335607b8c5c001ca35847c5ec22409ab04d83b05..76ac9c7d32ec7ee2e719e48d2956276676810d92 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -2063,7 +2063,7 @@ void wb_workfn(struct work_struct *work)
struct bdi_writeback, dwork);
long pages_written;
- set_worker_desc("flush-%s", dev_name(wb->bdi->dev));
+ set_worker_desc("flush-%s", bdi_dev_name(wb->bdi));
current->flags |= PF_SWAPWRITE;
if (likely(!current_is_workqueue_rescuer() ||
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 97967ce06de3342f951f0d36c4b7a4e082a1b0d7..f88197c1ffc2db0fcdbc5b9ab0c9d8b0f95fec43 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -13,6 +13,7 @@
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/blkdev.h>
+#include <linux/device.h>
#include <linux/writeback.h>
#include <linux/blk-cgroup.h>
#include <linux/backing-dev-defs.h>
@@ -504,4 +505,13 @@ static inline int bdi_rw_congested(struct backing_dev_info *bdi)
(1 << WB_async_congested));
}
+extern const char *bdi_unknown_name;
+
+static inline const char *bdi_dev_name(struct backing_dev_info *bdi)
+{
+ if (!bdi || !bdi->dev)
+ return bdi_unknown_name;
+ return dev_name(bdi->dev);
+}
+
#endif /* _LINUX_BACKING_DEV_H */
diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h
index ef50be4e5e6cae80bb260b23e3a3f5c066d7d135..d94def25e4dc94098648cf9a2568f75f0e2865b3 100644
--- a/include/trace/events/writeback.h
+++ b/include/trace/events/writeback.h
@@ -67,8 +67,8 @@ DECLARE_EVENT_CLASS(writeback_page_template,
TP_fast_assign(
strscpy_pad(__entry->name,
- mapping ? dev_name(inode_to_bdi(mapping->host)->dev) : "(unknown)",
- 32);
+ bdi_dev_name(mapping ? inode_to_bdi(mapping->host) :
+ NULL), 32);
__entry->ino = mapping ? mapping->host->i_ino : 0;
__entry->index = page->index;
),
@@ -111,8 +111,7 @@ DECLARE_EVENT_CLASS(writeback_dirty_inode_template,
struct backing_dev_info *bdi = inode_to_bdi(inode);
/* may be called for files on pseudo FSes w/ unregistered bdi */
- strscpy_pad(__entry->name,
- bdi->dev ? dev_name(bdi->dev) : "(unknown)", 32);
+ strscpy_pad(__entry->name, bdi_dev_name(bdi), 32);
__entry->ino = inode->i_ino;
__entry->state = inode->i_state;
__entry->flags = flags;
@@ -193,7 +192,7 @@ TRACE_EVENT(inode_foreign_history,
),
TP_fast_assign(
- strncpy(__entry->name, dev_name(inode_to_bdi(inode)->dev), 32);
+ strncpy(__entry->name, bdi_dev_name(inode_to_bdi(inode)), 32);
__entry->ino = inode->i_ino;
__entry->cgroup_ino = __trace_wbc_assign_cgroup(wbc);
__entry->history = history;
@@ -222,7 +221,7 @@ TRACE_EVENT(inode_switch_wbs,
),
TP_fast_assign(
- strncpy(__entry->name, dev_name(old_wb->bdi->dev), 32);
+ strncpy(__entry->name, bdi_dev_name(old_wb->bdi), 32);
__entry->ino = inode->i_ino;
__entry->old_cgroup_ino = __trace_wb_assign_cgroup(old_wb);
__entry->new_cgroup_ino = __trace_wb_assign_cgroup(new_wb);
@@ -255,7 +254,7 @@ TRACE_EVENT(track_foreign_dirty,
struct address_space *mapping = page_mapping(page);
struct inode *inode = mapping ? mapping->host : NULL;
- strncpy(__entry->name, dev_name(wb->bdi->dev), 32);
+ strncpy(__entry->name, bdi_dev_name(wb->bdi), 32);
__entry->bdi_id = wb->bdi->id;
__entry->ino = inode ? inode->i_ino : 0;
__entry->memcg_id = wb->memcg_css->id;
@@ -288,7 +287,7 @@ TRACE_EVENT(flush_foreign,
),
TP_fast_assign(
- strncpy(__entry->name, dev_name(wb->bdi->dev), 32);
+ strncpy(__entry->name, bdi_dev_name(wb->bdi), 32);
__entry->cgroup_ino = __trace_wb_assign_cgroup(wb);
__entry->frn_bdi_id = frn_bdi_id;
__entry->frn_memcg_id = frn_memcg_id;
@@ -318,7 +317,7 @@ DECLARE_EVENT_CLASS(writeback_write_inode_template,
TP_fast_assign(
strscpy_pad(__entry->name,
- dev_name(inode_to_bdi(inode)->dev), 32);
+ bdi_dev_name(inode_to_bdi(inode)), 32);
__entry->ino = inode->i_ino;
__entry->sync_mode = wbc->sync_mode;
__entry->cgroup_ino = __trace_wbc_assign_cgroup(wbc);
@@ -361,9 +360,7 @@ DECLARE_EVENT_CLASS(writeback_work_class,
__field(ino_t, cgroup_ino)
),
TP_fast_assign(
- strscpy_pad(__entry->name,
- wb->bdi->dev ? dev_name(wb->bdi->dev) :
- "(unknown)", 32);
+ strscpy_pad(__entry->name, bdi_dev_name(wb->bdi), 32);
__entry->nr_pages = work->nr_pages;
__entry->sb_dev = work->sb ? work->sb->s_dev : 0;
__entry->sync_mode = work->sync_mode;
@@ -416,7 +413,7 @@ DECLARE_EVENT_CLASS(writeback_class,
__field(ino_t, cgroup_ino)
),
TP_fast_assign(
- strscpy_pad(__entry->name, dev_name(wb->bdi->dev), 32);
+ strscpy_pad(__entry->name, bdi_dev_name(wb->bdi), 32);
__entry->cgroup_ino = __trace_wb_assign_cgroup(wb);
),
TP_printk("bdi %s: cgroup_ino=%lu",
@@ -438,7 +435,7 @@ TRACE_EVENT(writeback_bdi_register,
__array(char, name, 32)
),
TP_fast_assign(
- strscpy_pad(__entry->name, dev_name(bdi->dev), 32);
+ strscpy_pad(__entry->name, bdi_dev_name(bdi), 32);
),
TP_printk("bdi %s",
__entry->name
@@ -463,7 +460,7 @@ DECLARE_EVENT_CLASS(wbc_class,
),
TP_fast_assign(
- strscpy_pad(__entry->name, dev_name(bdi->dev), 32);
+ strscpy_pad(__entry->name, bdi_dev_name(bdi), 32);
__entry->nr_to_write = wbc->nr_to_write;
__entry->pages_skipped = wbc->pages_skipped;
__entry->sync_mode = wbc->sync_mode;
@@ -514,7 +511,7 @@ TRACE_EVENT(writeback_queue_io,
),
TP_fast_assign(
unsigned long *older_than_this = work->older_than_this;
- strscpy_pad(__entry->name, dev_name(wb->bdi->dev), 32);
+ strscpy_pad(__entry->name, bdi_dev_name(wb->bdi), 32);
__entry->older = older_than_this ? *older_than_this : 0;
__entry->age = older_than_this ?
(jiffies - *older_than_this) * 1000 / HZ : -1;
@@ -600,7 +597,7 @@ TRACE_EVENT(bdi_dirty_ratelimit,
),
TP_fast_assign(
- strscpy_pad(__entry->bdi, dev_name(wb->bdi->dev), 32);
+ strscpy_pad(__entry->bdi, bdi_dev_name(wb->bdi), 32);
__entry->write_bw = KBps(wb->write_bandwidth);
__entry->avg_write_bw = KBps(wb->avg_write_bandwidth);
__entry->dirty_rate = KBps(dirty_rate);
@@ -665,7 +662,7 @@ TRACE_EVENT(balance_dirty_pages,
TP_fast_assign(
unsigned long freerun = (thresh + bg_thresh) / 2;
- strscpy_pad(__entry->bdi, dev_name(wb->bdi->dev), 32);
+ strscpy_pad(__entry->bdi, bdi_dev_name(wb->bdi), 32);
__entry->limit = global_wb_domain.dirty_limit;
__entry->setpoint = (global_wb_domain.dirty_limit +
@@ -726,7 +723,7 @@ TRACE_EVENT(writeback_sb_inodes_requeue,
TP_fast_assign(
strscpy_pad(__entry->name,
- dev_name(inode_to_bdi(inode)->dev), 32);
+ bdi_dev_name(inode_to_bdi(inode)), 32);
__entry->ino = inode->i_ino;
__entry->state = inode->i_state;
__entry->dirtied_when = inode->dirtied_when;
@@ -800,7 +797,7 @@ DECLARE_EVENT_CLASS(writeback_single_inode_template,
TP_fast_assign(
strscpy_pad(__entry->name,
- dev_name(inode_to_bdi(inode)->dev), 32);
+ bdi_dev_name(inode_to_bdi(inode)), 32);
__entry->ino = inode->i_ino;
__entry->state = inode->i_state;
__entry->dirtied_when = inode->dirtied_when;
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index c360f6a6c8443fe6a78d325fefd2d6c45338e38c..62f05f605fb5b30c1f4a047480dedf4e7509e13a 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -21,6 +21,7 @@ struct backing_dev_info noop_backing_dev_info = {
EXPORT_SYMBOL_GPL(noop_backing_dev_info);
static struct class *bdi_class;
+const char *bdi_unknown_name = "(unknown)";
/*
* bdi_lock protects bdi_tree and updates to bdi_list. bdi_list has RCU