Merge branches 'upstream' and 'upstream-fixes' into for-linus

[pandora-kernel.git] / fs / libfs.c

diff --git a/fs/libfs.c b/fs/libfs.c
index 0a9da95..62baa03 100644 (file)
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -913,6 +913,35 @@ int generic_file_fsync(struct file *file, int datasync)
 }
 EXPORT_SYMBOL(generic_file_fsync);
 
+/**
+ * generic_check_addressable - Check addressability of file system
+ * @blocksize_bits:    log of file system block size
+ * @num_blocks:                number of blocks in file system
+ *
+ * Determine whether a file system with @num_blocks blocks (and a
+ * block size of 2**@blocksize_bits) is addressable by the sector_t
+ * and page cache of the system.  Return 0 if so and -EFBIG otherwise.
+ */
+int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks)
+{
+       u64 last_fs_block = num_blocks - 1;
+       u64 last_fs_page =
+               last_fs_block >> (PAGE_CACHE_SHIFT - blocksize_bits);
+
+       if (unlikely(num_blocks == 0))
+               return 0;
+
+       if ((blocksize_bits < 9) || (blocksize_bits > PAGE_CACHE_SHIFT))
+               return -EINVAL;
+
+       if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) ||
+           (last_fs_page > (pgoff_t)(~0ULL))) {
+               return -EFBIG;
+       }
+       return 0;
+}
+EXPORT_SYMBOL(generic_check_addressable);
+
 /*
  * No-op implementation of ->fsync for in-memory filesystems.
  */