[sheepdog] [PATCH] ec: make data strip as 512B to make VM and mkfs happy

[Liu Yuan]

1K is not suitable for some softwares like mkfs because it is operating on
sector size.

With sbd inserted,

# sbd0 mapped to an erasure coded vdi
$ mkfs.xfs -f /dev/sbd0 && xfs_check /dev/sbd0

will report error. Setting data strip as 512B solve the problem. This also
fixes the possible size problem in VM.

Signed-off-by: Liu Yuan <namei.unix at gmail.com>
---
 include/fec.h | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/include/fec.h b/include/fec.h
index 0297f33..b3c6e55 100644
--- a/include/fec.h
+++ b/include/fec.h
@@ -107,16 +107,8 @@ void fec_decode(const struct fec *code,
 		uint8_t *const *const outpkts,
 		const int *const index, size_t sz);
 
-/*
- * data stripe <= 1K is the safe value to run VM after some experimentations.
- *
- * Though most OS's file system will operate on 4K block, some softwares like
- * grub will operate on 512 bytes and Linux kernel itself will sometimes
- * operate on 1K blocks. I have tried 4K alignement and centos6 installation
- * failed (grub got screwed) and 1K is probably the biggest value if we want
- * VM to run on erasure coded volume.
- */
-#define SD_EC_DATA_STRIPE_SIZE (1024) /* 1K */
+/* Set data stripe as sector size to make VM happy */
+#define SD_EC_DATA_STRIPE_SIZE (512) /* 512 Byte */
 #define SD_EC_NR_STRIPE_PER_OBJECT (SD_DATA_OBJ_SIZE / SD_EC_DATA_STRIPE_SIZE)
 #define SD_EC_MAX_STRIP (16)
 
-- 
1.8.1.2