UBIFS: respect MS_SILENT mount flag

When attempting to mount a non-ubifs formatted volume, lots of error
messages (including a stack dump) are thrown to the kernel log even if
the MS_SILENT mount flag is set.
Fix this by introducing adding an additional state-variable in
struct ubifs_info and suppress error messages in ubifs_read_node if
MS_SILENT is set.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

3 files changed, 26 insertions, 8 deletions

diff --git a/fs/ubifs/io.c b/fs/ubifs/io.c
index e18b9889a51b..2290d5866725 100644
--- a/fs/ubifs/io.c
+++ b/fs/ubifs/io.c
@@ -988,30 +988,32 @@ int ubifs_read_node(const struct ubifs_info *c, void *buf, int type, int len,
                 return err;
 
         if (type != ch->node_type) {
-                ubifs_err("bad node type (%d but expected %d)",
-                          ch->node_type, type);
+                ubifs_errc(c, "bad node type (%d but expected %d)",
+                           ch->node_type, type);
                 goto out;
         }
 
         err = ubifs_check_node(c, buf, lnum, offs, 0, 0);
         if (err) {
-                ubifs_err("expected node type %d", type);
+                ubifs_errc(c, "expected node type %d", type);
                 return err;
         }
 
         l = le32_to_cpu(ch->len);
         if (l != len) {
-                ubifs_err("bad node length %d, expected %d", l, len);
+                ubifs_errc(c, "bad node length %d, expected %d", l, len);
                 goto out;
         }
 
         return 0;
 
 out:
-        ubifs_err("bad node at LEB %d:%d, LEB mapping status %d", lnum, offs,
-                  ubi_is_mapped(c->ubi, lnum));
-        ubifs_dump_node(c, buf);
-        dump_stack();
+        ubifs_errc(c, "bad node at LEB %d:%d, LEB mapping status %d", lnum,
+                   offs, ubi_is_mapped(c->ubi, lnum));
+        if (!c->probing) {
+                ubifs_dump_node(c, buf);
+                dump_stack();
+        }
         return -EINVAL;
 }
 
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index a81c7b556896..3904c8574ef9 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -1149,6 +1149,9 @@ static int mount_ubifs(struct ubifs_info *c)
         size_t sz;
 
         c->ro_mount = !!(c->vfs_sb->s_flags & MS_RDONLY);
+        /* Suppress error messages while probing if MS_SILENT is set */
+        c->probing = !!(c->vfs_sb->s_flags & MS_SILENT);
+
         err = init_constants_early(c);
         if (err)
                 return err;
@@ -1214,6 +1217,8 @@ static int mount_ubifs(struct ubifs_info *c)
         if (err)
                 goto out_free;
 
+        c->probing = 0;
+
         /*
          * Make sure the compressor which is set as default in the superblock
          * or overridden by mount options is actually compiled in.
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index e8c8cfe1435c..c1f71fe17cc0 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -51,6 +51,15 @@
 #define ubifs_warn(fmt, ...)                                        \
         pr_warn("UBIFS warning (pid %d): %s: " fmt "\n",            \
                 current->pid, __func__, ##__VA_ARGS__)
+/*
+ * A variant of 'ubifs_err()' which takes the UBIFS file-sytem description
+ * object as an argument.
+ */
+#define ubifs_errc(c, fmt, ...)                                     \
+        do {                                                        \
+                if (!(c)->probing)                                  \
+                        ubifs_err(fmt, ##__VA_ARGS__);              \
+        } while (0)
 
 /* UBIFS file system VFS magic number */
 #define UBIFS_SUPER_MAGIC 0x24051905
@@ -1209,6 +1218,7 @@ struct ubifs_debug_info;
  * @need_recovery: %1 if the file-system needs recovery
  * @replaying: %1 during journal replay
  * @mounting: %1 while mounting
+ * @probing: %1 while attempting to mount if MS_SILENT mount flag is set
  * @remounting_rw: %1 while re-mounting from R/O mode to R/W mode
  * @replay_list: temporary list used during journal replay
  * @replay_buds: list of buds to replay
@@ -1441,6 +1451,7 @@ struct ubifs_info {
         unsigned int replaying:1;
         unsigned int mounting:1;
         unsigned int remounting_rw:1;
+        unsigned int probing:1;
         struct list_head replay_list;
         struct list_head replay_buds;
         unsigned long long cs_sqnum;