[JFFS2] Handle inodes with only a single metadata node with non-zero isize

This should never happen unless there's corruption on the medium and the
actual data nodes go missing. But the failure mode (an oops when we assume
the fragtree isn't empty and go looking for its last node) isn't useful.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

1 files changed, 7 insertions, 2 deletions

diff --git a/fs/jffs2/readinode.c b/fs/jffs2/readinode.c
index a42ffba2ed17..6aff38930b50 100644
--- a/fs/jffs2/readinode.c
+++ b/fs/jffs2/readinode.c
@@ -1132,7 +1132,7 @@ static int jffs2_do_read_inode_internal(struct jffs2_sb_info *c,
                                         struct jffs2_raw_inode *latest_node)
 {
         struct jffs2_readinode_info rii;
-        uint32_t crc;
+        uint32_t crc, new_size;
         size_t retlen;
         int ret;
 
@@ -1233,7 +1233,12 @@ static int jffs2_do_read_inode_internal(struct jffs2_sb_info *c,
 
         case S_IFREG:
                 /* If it was a regular file, truncate it to the latest node's isize */
-                jffs2_truncate_fragtree(c, &f->fragtree, je32_to_cpu(latest_node->isize));
+                new_size = jffs2_truncate_fragtree(c, &f->fragtree, je32_to_cpu(latest_node->isize));
+                if (new_size != je32_to_cpu(latest_node->isize)) {
+                        JFFS2_WARNING("Truncating ino #%u to %d bytes failed because it only had %d bytes to start with!\n",
+                                      f->inocache->ino, je32_to_cpu(latest_node->isize), new_size);
+                        latest_node->isize = cpu_to_je32(new_size);
+                }
                 break;
 
         case S_IFLNK: