1 files changed, 42 insertions, 3 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 64067de70c6f..c79e46b7f159 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1600,19 +1600,58 @@ static void ext4_orphan_cleanup (struct super_block * sb,
 #endif
         sb->s_flags = s_flags; /* Restore MS_RDONLY status */
 }
+/*
+ * Maximal extent format file size.
+ * Resulting logical blkno at s_maxbytes must fit in our on-disk
+ * extent format containers, within a sector_t, and within i_blocks
+ * in the vfs.  ext4 inode has 48 bits of i_block in fsblock units,
+ * so that won't be a limiting factor.
+ *
+ * Note, this does *not* consider any metadata overhead for vfs i_blocks.
+ */
+static loff_t ext4_max_size(int blkbits)
+{
+        loff_t res;
+        loff_t upper_limit = MAX_LFS_FILESIZE;
+
+        /* small i_blocks in vfs inode? */
+        if (sizeof(blkcnt_t) < sizeof(u64)) {
+                /*
+                 * CONFIG_LSF is not enabled implies the inode
+                 * i_block represent total blocks in 512 bytes
+                 * 32 == size of vfs inode i_blocks * 8
+                 */
+                upper_limit = (1LL << 32) - 1;
+
+                /* total blocks in file system block size */
+                upper_limit >>= (blkbits - 9);
+                upper_limit <<= blkbits;
+        }
+
+        /* 32-bit extent-start container, ee_block */
+        res = 1LL << 32;
+        res <<= blkbits;
+        res -= 1;
+
+        /* Sanity check against vm- & vfs- imposed limits */
+        if (res > upper_limit)
+                res = upper_limit;
+
+        return res;
+}
 
 /*
- * Maximal file size.  There is a direct, and {,double-,triple-}indirect
+ * Maximal bitmap file size.  There is a direct, and {,double-,triple-}indirect
  * block limit, and also a limit of (2^48 - 1) 512-byte sectors in i_blocks.
  * We need to be 1 filesystem block less than the 2^48 sector limit.
  */
-static loff_t ext4_max_size(int bits)
+static loff_t ext4_max_bitmap_size(int bits)
 {
         loff_t res = EXT4_NDIR_BLOCKS;
         int meta_blocks;
         loff_t upper_limit;
         /* This is calculated to be the largest file size for a
-         * dense, file such that the total number of
+         * dense, bitmapped file such that the total number of
          * sectors in the file, including data and all indirect blocks,
          * does not exceed 2^48 -1
          * __u32 i_blocks_lo and _u16 i_blocks_high representing the