[PATCH 2/2] block: Add new BLK_STS_FSCORRUPTED status

[Qu Wenruo <wqu@suse.com>]

There are quite a lot of filesystems doing their verification work done
at endio hook or hook before submitting bio.

Normally such verification returns -EUCLEAN/-EFSCORRUPTED to indicate
something unexpected, and some of such verification either use
bio->bi_status or users bio->bi_endio to return their value.

In such case, the missing of corresponding BLK_STS_ bit can lower
the severity just like:

  In endio function:
	return errno_to_blk_status(-EFSCORRUPTED);
 	^^^ -EFSCORRUPTED gets interpreted to BLK_STS_IOERR

  In the filesystem code:
	ret = blk_status_to_errno(bi->bi_status);
	^^^ BLK_STS_IOERR gets interpreted to -EIO;

This lowers the severity, making the filesystem layer to believe it's
just an ordinary error.

This patch will add a new BLK_STS_FSCORRUPTED, to allow -EFSCORRUPTED to
be converted to BLK_STS_FSCORRUPTED, and then converted back to
-EFSCORRUPTED without losing info.

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 block/blk-core.c          | 1 +
 include/linux/blk_types.h | 3 +++
 2 files changed, 4 insertions(+)

diff --git a/block/blk-core.c b/block/blk-core.c
index a55389ba8779..ba7acfc3d8e0 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -135,6 +135,7 @@ static const struct {
 	[BLK_STS_RESOURCE]	= { -ENOMEM,	"kernel resource" },
 	[BLK_STS_DEV_RESOURCE]	= { -EBUSY,	"device resource" },
 	[BLK_STS_AGAIN]		= { -EAGAIN,	"nonblocking retry" },
+	[BLK_STS_FSCORRUPTED]	= { -EFSCORRUPTED, "filesystem is corrupted" },
 
 	/* device mapper special case, should not leak out: */
 	[BLK_STS_DM_REQUEUE]	= { -EREMCHG, "dm internal retry" },
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 791fee35df88..8f70bbec6c83 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -63,6 +63,9 @@ typedef u8 __bitwise blk_status_t;
  */
 #define BLK_STS_DEV_RESOURCE	((__force blk_status_t)13)
 
+/* Normally filesystem layer generated error */
+#define BLK_STS_FSCORRUPTED	((__force blk_status_t)14)
+
 /**
  * blk_path_error - returns true if error may be path related
  * @error: status the request was completed with
-- 
2.21.0