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Message-Id: <20170531124540.8782-4-jlayton@redhat.com>
Date: Wed, 31 May 2017 08:45:26 -0400
From: Jeff Layton <jlayton@...hat.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
Al Viro <viro@...IV.linux.org.uk>, Jan Kara <jack@...e.cz>,
tytso@....edu, axboe@...nel.dk, mawilcox@...rosoft.com,
ross.zwisler@...ux.intel.com, corbet@....net
Cc: linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
linux-doc@...r.kernel.org
Subject: [PATCH v5 03/17] mm: tracepoints for writeback error events
To enable that, make __errseq_set return the value that it was set to
we exit the loop. Take heed that that value is not suitable as a later
"since" value, as it will not have been marked seen.
Signed-off-by: Jeff Layton <jlayton@...hat.com>
---
include/linux/errseq.h | 2 +-
include/linux/fs.h | 5 +++-
include/trace/events/filemap.h | 55 ++++++++++++++++++++++++++++++++++++++++++
lib/errseq.c | 20 ++++++++++-----
mm/filemap.c | 13 +++++++++-
5 files changed, 86 insertions(+), 9 deletions(-)
diff --git a/include/linux/errseq.h b/include/linux/errseq.h
index 0d2555f310cd..9e0d444ac88d 100644
--- a/include/linux/errseq.h
+++ b/include/linux/errseq.h
@@ -5,7 +5,7 @@
typedef u32 errseq_t;
-void __errseq_set(errseq_t *eseq, int err);
+errseq_t __errseq_set(errseq_t *eseq, int err);
static inline void errseq_set(errseq_t *eseq, int err)
{
/* Optimize for the common case of no error */
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 24178107379d..293cbc7f3520 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2528,6 +2528,7 @@ extern int filemap_fdatawrite_range(struct address_space *mapping,
extern int filemap_check_errors(struct address_space *mapping);
extern int __must_check filemap_report_wb_err(struct file *file);
+extern void __filemap_set_wb_err(struct address_space *mapping, int err);
/**
* filemap_set_wb_err - set a writeback error on an address_space
@@ -2547,7 +2548,9 @@ extern int __must_check filemap_report_wb_err(struct file *file);
*/
static inline void filemap_set_wb_err(struct address_space *mapping, int err)
{
- errseq_set(&mapping->wb_err, err);
+ /* Fastpath for common case of no error */
+ if (unlikely(err))
+ __filemap_set_wb_err(mapping, err);
}
/**
diff --git a/include/trace/events/filemap.h b/include/trace/events/filemap.h
index 42febb6bc1d5..2af66920f267 100644
--- a/include/trace/events/filemap.h
+++ b/include/trace/events/filemap.h
@@ -10,6 +10,7 @@
#include <linux/memcontrol.h>
#include <linux/device.h>
#include <linux/kdev_t.h>
+#include <linux/errseq.h>
DECLARE_EVENT_CLASS(mm_filemap_op_page_cache,
@@ -52,6 +53,60 @@ DEFINE_EVENT(mm_filemap_op_page_cache, mm_filemap_add_to_page_cache,
TP_ARGS(page)
);
+TRACE_EVENT(filemap_set_wb_err,
+ TP_PROTO(struct address_space *mapping, errseq_t eseq),
+
+ TP_ARGS(mapping, eseq),
+
+ TP_STRUCT__entry(
+ __field(unsigned long, i_ino)
+ __field(dev_t, s_dev)
+ __field(errseq_t, errseq)
+ ),
+
+ TP_fast_assign(
+ __entry->i_ino = mapping->host->i_ino;
+ __entry->errseq = eseq;
+ if (mapping->host->i_sb)
+ __entry->s_dev = mapping->host->i_sb->s_dev;
+ else
+ __entry->s_dev = mapping->host->i_rdev;
+ ),
+
+ TP_printk("dev=%d:%d ino=0x%lx errseq=0x%x",
+ MAJOR(__entry->s_dev), MINOR(__entry->s_dev),
+ __entry->i_ino, __entry->errseq)
+);
+
+TRACE_EVENT(filemap_report_wb_err,
+ TP_PROTO(struct file *file, errseq_t old),
+
+ TP_ARGS(file, old),
+
+ TP_STRUCT__entry(
+ __field(struct file *, file);
+ __field(unsigned long, i_ino)
+ __field(dev_t, s_dev)
+ __field(errseq_t, old)
+ __field(errseq_t, new)
+ ),
+
+ TP_fast_assign(
+ __entry->file = file;
+ __entry->i_ino = file->f_mapping->host->i_ino;
+ if (file->f_mapping->host->i_sb)
+ __entry->s_dev = file->f_mapping->host->i_sb->s_dev;
+ else
+ __entry->s_dev = file->f_mapping->host->i_rdev;
+ __entry->old = old;
+ __entry->new = file->f_wb_err;
+ ),
+
+ TP_printk("file=%p dev=%d:%d ino=0x%lx old=0x%x new=0x%x",
+ __entry->file, MAJOR(__entry->s_dev),
+ MINOR(__entry->s_dev), __entry->i_ino, __entry->old,
+ __entry->new)
+);
#endif /* _TRACE_FILEMAP_H */
/* This part must be outside protection */
diff --git a/lib/errseq.c b/lib/errseq.c
index d129c0611c1f..009972d3000c 100644
--- a/lib/errseq.c
+++ b/lib/errseq.c
@@ -52,10 +52,14 @@
*
* Most callers will want to use the errseq_set inline wrapper to efficiently
* handle the common case where err is 0.
+ *
+ * We do return an errseq_t here, primarily for debugging purposes. The return
+ * value should not be used as a previously sampled value in later calls as it
+ * will not have the SEEN flag set.
*/
-void __errseq_set(errseq_t *eseq, int err)
+errseq_t __errseq_set(errseq_t *eseq, int err)
{
- errseq_t old;
+ errseq_t cur, old;
/* MAX_ERRNO must be able to serve as a mask */
BUILD_BUG_ON_NOT_POWER_OF_2(MAX_ERRNO + 1);
@@ -66,13 +70,14 @@ void __errseq_set(errseq_t *eseq, int err)
* also don't accept zero here as that would effectively clear a
* previous error.
*/
+ old = READ_ONCE(*eseq);
+
if (WARN(unlikely(err == 0 || (unsigned int)-err > MAX_ERRNO),
"err = %d\n", err))
- return;
+ return old;
- old = READ_ONCE(*eseq);
for (;;) {
- errseq_t new, cur;
+ errseq_t new;
/* Clear out error bits and set new error */
new = (old & ~(MAX_ERRNO|ERRSEQ_SEEN)) | -err;
@@ -82,8 +87,10 @@ void __errseq_set(errseq_t *eseq, int err)
new += ERRSEQ_CTR_INC;
/* If there would be no change, then call it done */
- if (new == old)
+ if (new == old) {
+ cur = new;
break;
+ }
/* Try to swap the new value into place */
cur = cmpxchg(eseq, old, new);
@@ -98,6 +105,7 @@ void __errseq_set(errseq_t *eseq, int err)
/* Raced with an update, try again */
old = cur;
}
+ return cur;
}
EXPORT_SYMBOL(__errseq_set);
diff --git a/mm/filemap.c b/mm/filemap.c
index aeb58db10688..c5e19ea0bf12 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -535,6 +535,14 @@ int filemap_write_and_wait_range(struct address_space *mapping,
}
EXPORT_SYMBOL(filemap_write_and_wait_range);
+void __filemap_set_wb_err(struct address_space *mapping, int err)
+{
+ errseq_t eseq = __errseq_set(&mapping->wb_err, err);
+ trace_filemap_set_wb_err(mapping, eseq);
+
+}
+EXPORT_SYMBOL(__filemap_set_wb_err);
+
/**
* filemap_report_wb_err - report wb error (if any) that was previously set
* @file: struct file on which the error is being reported
@@ -559,14 +567,17 @@ EXPORT_SYMBOL(filemap_write_and_wait_range);
int filemap_report_wb_err(struct file *file)
{
int err = 0;
+ errseq_t old = READ_ONCE(file->f_wb_err);
struct address_space *mapping = file->f_mapping;
/* Locklessly handle the common case where nothing has changed */
- if (errseq_check(&mapping->wb_err, READ_ONCE(file->f_wb_err))) {
+ if (errseq_check(&mapping->wb_err, old)) {
/* Something changed, must use slow path */
spin_lock(&file->f_lock);
+ old = file->f_wb_err;
err = errseq_check_and_advance(&mapping->wb_err,
&file->f_wb_err);
+ trace_filemap_report_wb_err(file, old);
spin_unlock(&file->f_lock);
}
return err;
--
2.9.4
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