X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=include%2Flinux%2Fjournal-head.h;h=98cd41bb39c8667953c10030ef32f2945765f7e8;hb=07318247213c8a57198b2866b52ac74dac7eb266;hp=13a3da25ff0752a99bccb12b9c105cdbdae13457;hpb=f35546e072a7a86ccb950d4d1508879b0d49e374;p=firefly-linux-kernel-4.4.55.git

diff --git a/include/linux/journal-head.h b/include/linux/journal-head.h
index 13a3da25ff07..98cd41bb39c8 100644
--- a/include/linux/journal-head.h
+++ b/include/linux/journal-head.h
@@ -30,15 +30,19 @@ struct journal_head {
 
 	/*
 	 * Journalling list for this buffer [jbd_lock_bh_state()]
+	 * NOTE: We *cannot* combine this with b_modified into a bitfield
+	 * as gcc would then (which the C standard allows but which is
+	 * very unuseful) make 64-bit accesses to the bitfield and clobber
+	 * b_jcount if its update races with bitfield modification.
 	 */
-	unsigned b_jlist:4;
+	unsigned b_jlist;
 
 	/*
 	 * This flag signals the buffer has been modified by
 	 * the currently running transaction
 	 * [jbd_lock_bh_state()]
 	 */
-	unsigned b_modified:1;
+	unsigned b_modified;
 
 	/*
 	 * Copy of the buffer data frozen for writing to the log.