block: introduce new block status code type

Currently we use nornal Linux errno values in the block layer, and while
we accept any error a few have overloaded magic meanings.  This patch
instead introduces a new  blk_status_t value that holds block layer specific
status codes and explicitly explains their meaning.  Helpers to convert from
and to the previous special meanings are provided for now, but I suspect
we want to get rid of them in the long run - those drivers that have a
errno input (e.g. networking) usually get errnos that don't know about
the special block layer overloads, and similarly returning them to userspace
will usually return somethings that strictly speaking isn't correct
for file system operations, but that's left as an exercise for later.

For now the set of errors is a very limited set that closely corresponds
to the previous overloaded errno values, but there is some low hanging
fruite to improve it.

blk_status_t (ab)uses the sparse __bitwise annotations to allow for sparse
typechecking, so that we can easily catch places passing the wrong values.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/target/target_core_pscsi.c b/drivers/target/target_core_pscsi.c
index 3e4abb13f8ea..323ab47645d0 100644
--- a/drivers/target/target_core_pscsi.c
+++ b/drivers/target/target_core_pscsi.c
@@ -55,7 +55,7 @@ static inline struct pscsi_dev_virt *PSCSI_DEV(struct se_device *dev)
 }
 
 static sense_reason_t pscsi_execute_cmd(struct se_cmd *cmd);
-static void pscsi_req_done(struct request *, int);
+static void pscsi_req_done(struct request *, blk_status_t);
 
 /*	pscsi_attach_hba():
  *
@@ -1045,7 +1045,7 @@ static sector_t pscsi_get_blocks(struct se_device *dev)
 	return 0;
 }
 
-static void pscsi_req_done(struct request *req, int uptodate)
+static void pscsi_req_done(struct request *req, blk_status_t status)
 {
 	struct se_cmd *cmd = req->end_io_data;
 	struct pscsi_plugin_task *pt = cmd->priv;