From: "Luis R. Rodriguez" mcgrof@kernel.org
[ Upstream commit 41124db869b7e00e12052555f8987867ac01d70c ]
kmod <= v19 was broken -- it could return 0 to modprobe calls, incorrectly assuming that a kernel module was built-in, whereas in reality the module was just forming in the kernel. The reason for this is an incorrect userspace heuristics. A userspace kmod fix is available for it [0], however should userspace break again we could go on with an failed get_fs_type() which is hard to debug as the request_module() is detected as returning 0. The first suspect would be that there is something worth with the kernel's module loader and obviously in this case that is not the issue.
Since these issues are painful to debug complain when we know userspace has outright lied to us.
[0] http://git.kernel.org/cgit/utils/kernel/kmod/kmod.git/commit/libkmod/libkmod...
Suggested-by: Rusty Russell rusty@rustcorp.com.au Cc: Jessica Yu jeyu@redhat.com Signed-off-by: Luis R. Rodriguez mcgrof@kernel.org Signed-off-by: Al Viro viro@zeniv.linux.org.uk Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- fs/filesystems.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/filesystems.c b/fs/filesystems.c index c5618db110be..cd7ba6301a60 100644 --- a/fs/filesystems.c +++ b/fs/filesystems.c @@ -275,8 +275,10 @@ struct file_system_type *get_fs_type(const char *name) int len = dot ? dot - name : strlen(name);
fs = __get_fs_type(name, len); - if (!fs && (request_module("fs-%.*s", len, name) == 0)) + if (!fs && (request_module("fs-%.*s", len, name) == 0)) { fs = __get_fs_type(name, len); + WARN_ONCE(!fs, "request_module fs-%.*s succeeded, but still no fs?\n", len, name); + }
if (dot && fs && !(fs->fs_flags & FS_HAS_SUBTYPE)) { put_filesystem(fs);