After we lost ustat(2) in commit 4e7a824, we ended up with a slightly
bonkers method to determine if our target block device was mounted:
it goes through every entry returned by getmntent and stats the dir
to see if its underlying device matches ours.
Unfortunately that dir might be a hung nfs server and sadness ensues.
So do some pre-checks; can we stat the mounted "device?" If so is
it really a block device? If not, skip it.
Fixes: 4e7a824 ("libxfs/linux.c: Replace use of ustat by stat")
Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
---
diff --git a/libxfs/linux.c b/libxfs/linux.c
index 0bace3e..7350fa7 100644
--- a/libxfs/linux.c
+++ b/libxfs/linux.c
@@ -77,7 +77,21 @@ platform_check_mount(char *name, char *block, struct stat *s, int flags)
progname, name);
return 1;
}
+ /*
+ * This whole business is to work out if our block device is mounted
+ * after we lost ustat(2), see:
+ * 4e7a824 libxfs/linux.c: Replace use of ustat by stat
+ * We don't really want to stat every single mounted directory,
+ * as that may include tmpfs, cgroups, procfs or - worst - hung nfs
+ * servers. So we check the "device" before going after the mountpoint.
+ */
while ((mnt = getmntent(f)) != NULL) {
+ /* If the "fsname" is't a stat-able device, skip it */
+ if (stat(mnt->mnt_fsname, &mst) < 0)
+ continue;
+ if (!S_ISBLK(mst.st_mode))
+ continue;
+ /* Ok, this entry does seem to be a mounted block device */
if (stat(mnt->mnt_dir, &mst) < 0)
continue;
if (mst.st_dev != s->st_rdev)
--
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