nilfs2: reject filesystem with unsupported block size

This inserts sanity check that refuses to mount a filesystem with
unsupported block size.

Previously, kernel code of nilfs was looking only limitation of
devices though mkfs.nilfs2 limits the range of block sizes; there was
no check that prevents rec_len overflow with larger block sizes.

With this change, block sizes larger than 64KB or smaller than 1KB
will get rejected explicitly by kernel.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

2 files changed, 14 insertions, 1 deletions

diff --git a/fs/nilfs2/the_nilfs.c b/fs/nilfs2/the_nilfs.c
index da67b560f3c3..37de1f062d81 100644
--- a/fs/nilfs2/the_nilfs.c
+++ b/fs/nilfs2/the_nilfs.c
@@ -671,7 +671,7 @@ int init_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi, char *data)
                 goto out;
         }
 
-        blocksize = sb_min_blocksize(sb, BLOCK_SIZE);
+        blocksize = sb_min_blocksize(sb, NILFS_MIN_BLOCK_SIZE);
         if (!blocksize) {
                 printk(KERN_ERR "NILFS: unable to set blocksize\n");
                 err = -EINVAL;
@@ -690,6 +690,13 @@ int init_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi, char *data)
                 goto failed_sbh;
 
         blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
+        if (blocksize < NILFS_MIN_BLOCK_SIZE ||
+            blocksize > NILFS_MAX_BLOCK_SIZE) {
+                printk(KERN_ERR "NILFS: couldn't mount because of unsupported "
+                       "filesystem blocksize %d\n", blocksize);
+                err = -EINVAL;
+                goto failed_sbh;
+        }
         if (sb->s_blocksize != blocksize) {
                 int hw_blocksize = bdev_logical_block_size(sb->s_bdev);
 
diff --git a/include/linux/nilfs2_fs.h b/include/linux/nilfs2_fs.h
index 970828a5ffc5..f5487b6f91ed 100644
--- a/include/linux/nilfs2_fs.h
+++ b/include/linux/nilfs2_fs.h
@@ -287,6 +287,12 @@ struct nilfs_super_block {
 #define NILFS_NAME_LEN 255
 
 /*
+ * Block size limitations
+ */
+#define NILFS_MIN_BLOCK_SIZE            1024
+#define NILFS_MAX_BLOCK_SIZE            65536
+
+/*
  * The new version of the directory entry.  Since V0 structures are
  * stored in intel byte order, and the name_len field could never be
  * bigger than 255 chars, it's safe to reclaim the extra byte for the