Author: scottl
Date: Mon Nov 20 20:53:03 2017
New Revision: 326029
URL: https://svnweb.freebsd.org/changeset/base/326029
Log:
Update a comment in brelse() to match reality.
Modified:
head/sys/kern/vfs_bio.c
Modified: head/sys/kern/vfs_bio.c
==============================================================================
--- head/sys/kern/vfs_bio.c Mon Nov 20 20:05:30 2017 (r326028)
+++ head/sys/kern/vfs_bio.c Mon Nov 20 20:53:03 2017 (r326029)
@@ -2340,9 +2340,18 @@ brelse(struct buf *bp)
!(bp->b_flags & B_INVAL)) {
/*
* Failed write, redirty. All errors except ENXIO (which
- * means the device is gone) are expected to be potentially
- * transient - underlying media might work if tried again
- * after EIO, and memory might be available after an ENOMEM.
+ * means the device is gone) are treated as being
+ * transient.
+ *
+ * XXX Treating EIO as transient is not correct; the
+ * contract with the local storage device drivers is that
+ * they will only return EIO once the I/O is no longer
+ * retriable. Network I/O also respects this through the
+ * guarantees of TCP and/or the internal retries of NFS.
+ * ENOMEM might be transient, but we also have no way of
+ * knowing when its ok to retry/reschedule. In general,
+ * this entire case should be made obsolete through better
+ * error handling/recovery and resource scheduling.
*
* Do this also for buffers that failed with ENXIO, but have
* non-empty dependencies - the soft updates code might need
_______________________________________________
svn-src-head@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/svn-src-head
To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
