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Re: [dm-devel] Re: [RFC PATCH 1/4] convert block layer drivers to blkerr error values



James Bottomley wrote:
On Wed, 2005-08-24 at 12:21 -0700, Patrick Mansfield wrote:

On Wed, Aug 24, 2005 at 04:03:58AM -0500, Mike Christie wrote:


-#define end_io_error(uptodate)	(unlikely((uptodate) <= 0))
+enum {
+	BLK_SUCCESS = 0,	/* Must be zero for compat with old usage */
+	BLKERR_IO,		/* Generic I/O error */
+	BLKERR_NOTSUPP,		/* Operation is not supported */
+	BLKERR_WOULDBLOCK,	/* Operation would block */
+	BLKERR_FATAL_DRV,	/* Fatal driver error */
+	BLKERR_FATAL_DEV,	/* Fatal device error */
+	BLKERR_FATAL_XPT,	/* Fatal transport error */
+	BLKERR_RETRY_DRV,	/* Driver error, I/O may be retried */
+	BLKERR_RETRY_DEV,	/* Device error, I/O may be retried */
+	BLKERR_RETRY_XPT,	/* Transport error, I/O may retried */
+};


Actually, I'd really be happier if these were a bitmap rather than an
enumeration.  That way we can divide them easily into cause (Driver,
Device or Transport) and severity (fatal or retryable), so something
like dm-multipath would only be interested in errors it made sense for a
path to be failed over for (i.e. all transport and driver errors).


Would it be good then to also extend the fail fast flag to a bit map so dm-multipath can tell scsi that scsi should handle device errors?



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