tmpfs: per-superblock i_ino support

[linux-2.6-microblaze.git] / include / linux / fs.h

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 488c3ef..b1c3a14 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2946,6 +2946,21 @@ extern void discard_new_inode(struct inode *);
 extern unsigned int get_next_ino(void);
 extern void evict_inodes(struct super_block *sb);
 
+/*
+ * Userspace may rely on the the inode number being non-zero. For example, glibc
+ * simply ignores files with zero i_ino in unlink() and other places.
+ *
+ * As an additional complication, if userspace was compiled with
+ * _FILE_OFFSET_BITS=32 on a 64-bit kernel we'll only end up reading out the
+ * lower 32 bits, so we need to check that those aren't zero explicitly. With
+ * _FILE_OFFSET_BITS=64, this may cause some harmless false-negatives, but
+ * better safe than sorry.
+ */
+static inline bool is_zero_ino(ino_t ino)
+{
+       return (u32)ino == 0;
+}
+
 extern void __iget(struct inode * inode);
 extern void iget_failed(struct inode *);
 extern void clear_inode(struct inode *);