[sheepdog] [PATCH] md: don't use xattr for calculating path space

[Kai Zhang]

Currently, md calls init_path_space() for calculating path space after a path is pluged.
If the path is pluged for the first time, md will use statvfs() to calculate path space
ant set it to xattr. Next time when md calls init_path_space(), it will try to get path
space from xattr other than re-calculate it.

This works fine for most times.
However, if the path space changes for some reasons (for example, a lvm resize operation),
init_path_space() will return a wrong number, because xattr haven't changed.

This patch will let init_path_space() use statvfs() for calculating space for each time.

Signed-off-by: Kai Zhang <kyle at zelin.io>
---
 sheep/md.c |   31 ++++---------------------------
 1 files changed, 4 insertions(+), 27 deletions(-)

diff --git a/sheep/md.c b/sheep/md.c
index 291ffca..60dbd04 100644
--- a/sheep/md.c
+++ b/sheep/md.c
@@ -255,47 +255,24 @@ out:
 }
 
 /*
- * If path is broken during initilization or not support xattr return 0. We can
+ * If path is broken during initilization return 0. We can
  * safely use 0 to represent failure case  because 0 space path can be
  * considered as broken path.
  */
 static uint64_t init_path_space(char *path)
 {
-	uint64_t size;
+	uint64_t size = 0;
 	char stale[PATH_MAX];
 
-	if (!is_xattr_enabled(path)) {
-		sd_iprintf("multi-disk support need xattr feature");
-		goto broken_path;
-	}
-
 	snprintf(stale, PATH_MAX, "%s/.stale", path);
 	if (xmkdir(stale, sd_def_dmode) < 0) {
 		sd_eprintf("can't mkdir for %s, %m", stale);
-		goto broken_path;
-	}
-
-	if (getxattr(path, MDNAME, &size, MDSIZE) < 0) {
-		if (errno == ENODATA) {
-			goto create;
-		} else {
-			sd_eprintf("%s, %m", path);
-			goto broken_path;
-		}
+		goto out;
 	}
 
-	return size;
-create:
 	size = get_path_size(path, NULL);
-	if (!size)
-		goto broken_path;
-	if (setxattr(path, MDNAME, &size, MDSIZE, 0) < 0) {
-		sd_eprintf("%s, %m", path);
-		goto broken_path;
-	}
+out:
 	return size;
-broken_path:
-	return 0;
 }
 
 static inline void remove_disk(int idx)
-- 
1.7.1