LU-2099 osd: set dr_elapsed before dr_numreqs

so that service thread always get dr_elapsed and
dr_elapsed_valid initialized when the bio is done.
also, the patch adds a bit of debug to help with
the original bug if this patch doesn't help.

Signed-off-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Change-Id: I7c41af9a2be5be2f37190fb053d7449653fc7a99
Reviewed-on: http://review.whamcloud.com/4216
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>

diff --git a/lustre/osd-ldiskfs/osd_internal.h b/lustre/osd-ldiskfs/osd_internal.h
index 0a3480d..f01412d 100644 (file)
--- a/lustre/osd-ldiskfs/osd_internal.h
+++ b/lustre/osd-ldiskfs/osd_internal.h
@@ -504,6 +504,7 @@ struct osd_iobuf {
         unsigned long      dr_start_time;
         unsigned long      dr_elapsed;  /* how long io took */
         struct osd_device *dr_dev;
+       unsigned int       dr_init_at;  /* the line iobuf was initialized */
 };
 
 struct osd_thread_info {

diff --git a/lustre/osd-ldiskfs/osd_io.c b/lustre/osd-ldiskfs/osd_io.c
index 84aabbe..5626f5f 100644 (file)
--- a/lustre/osd-ldiskfs/osd_io.c
+++ b/lustre/osd-ldiskfs/osd_io.c
@@ -93,8 +93,14 @@ int generic_error_remove_page(struct address_space *mapping, struct page *page)
 }
 #endif
 
-static void osd_init_iobuf(struct osd_device *d, struct osd_iobuf *iobuf,int rw)
+static void __osd_init_iobuf(struct osd_device *d, struct osd_iobuf *iobuf,
+                            int rw, int line)
 {
+       LASSERTF(iobuf->dr_elapsed_valid == 0,
+                "iobuf %p, reqs %d, rw %d, line %d\n", iobuf,
+                cfs_atomic_read(&iobuf->dr_numreqs), iobuf->dr_rw,
+                iobuf->dr_init_at);
+
         cfs_waitq_init(&iobuf->dr_wait);
         cfs_atomic_set(&iobuf->dr_numreqs, 0);
         iobuf->dr_max_pages = PTLRPC_MAX_BRW_PAGES;
@@ -104,9 +110,10 @@ static void osd_init_iobuf(struct osd_device *d, struct osd_iobuf *iobuf,int rw)
         iobuf->dr_frags = 0;
         iobuf->dr_elapsed = 0;
         /* must be counted before, so assert */
-        LASSERT(iobuf->dr_elapsed_valid == 0);
         iobuf->dr_rw = rw;
+       iobuf->dr_init_at = line;
 }
+#define osd_init_iobuf(dev,iobuf,rw) __osd_init_iobuf(dev, iobuf, rw, __LINE__)
 
 static void osd_iobuf_add_page(struct osd_iobuf *iobuf, struct page *page)
 {
@@ -188,11 +195,19 @@ static int dio_complete_routine(struct bio *bio, unsigned int done, int error)
         if (error != 0 && iobuf->dr_error == 0)
                 iobuf->dr_error = error;
 
-        if (cfs_atomic_dec_and_test(&iobuf->dr_numreqs)) {
-                iobuf->dr_elapsed = jiffies - iobuf->dr_start_time;
-                iobuf->dr_elapsed_valid = 1;
-                cfs_waitq_signal(&iobuf->dr_wait);
-        }
+       /*
+        * set dr_elapsed before dr_numreqs turns to 0, otherwise
+        * it's possible that service thread will see dr_numreqs
+        * is zero, but dr_elapsed is not set yet, leading to lost
+        * data in this processing and an assertion in a subsequent
+        * call to OSD.
+        */
+       if (cfs_atomic_read(&iobuf->dr_numreqs) == 1) {
+               iobuf->dr_elapsed = jiffies - iobuf->dr_start_time;
+               iobuf->dr_elapsed_valid = 1;
+       }
+       if (cfs_atomic_dec_and_test(&iobuf->dr_numreqs))
+               cfs_waitq_signal(&iobuf->dr_wait);
 
         /* Completed bios used to be chained off iobuf->dr_bios and freed in
          * filter_clear_dreq().  It was then possible to exhaust the biovec-256