volume_id: abort early on read failures.

 should help with probing missing fdd's

1 files changed, 9 insertions, 3 deletions

diff --git a/util-linux/volume_id/util.c b/util-linux/volume_id/util.c
index 1a1b3f92e..dd75c7ba1 100644
--- a/util-linux/volume_id/util.c
+++ b/util-linux/volume_id/util.c
@@ -254,9 +254,15 @@ void *volume_id_get_buffer(struct volume_id *id, uint64_t off, size_t len)
                 dbg("requested 0x%x bytes, got 0x%x bytes",
                                 (unsigned) len, (unsigned) read_len);
  err:
-                /* id->seekbuf_len or id->sbbuf_len is wrong now! Fixing.
-                 * Most likely user will not do any additional
-                 * calls anyway, it's a corrupted fs or something. */
+                /* No filesystem can be this tiny. It's most likely
+                 * non-associated loop device, empty drive and so on.
+                 * Flag it, making it possible to short circuit future
+                 * accesses. Rationale:
+                 * users complained of slow blkid due to empty floppy drives.
+                 */
+                if (off < 64*1024)
+                        id->error = 1;
+                /* id->seekbuf_len or id->sbbuf_len is wrong now! Fixing. */
                 volume_id_free_buffer(id);
                 return NULL;
         }