ext4: support fast symlinks from ext3 file systems

407cd7fb83c0 (ext4: change fast symlink test to not rely on i_blocks)
broke ~10 years old ext3 file systems created by 2.6.17. Any ELF
executable fails because the /lib/ld-linux.so.2 fast symlink
cannot be read anymore.

The patch assumed fast symlinks were created in a specific way,
but that's not true on these really old file systems.

The new behavior is apparently needed only with the large EA inode
feature.

Revert to the old behavior if the large EA inode feature is not set.

This makes my old VM boot again.

Fixes: 407cd7fb83c0 (ext4: change fast symlink test to not rely on i_blocks)
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Cc: stable@vger.kernel.org

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 7df2c5644e59c9678e9379985338f972a69d42d1..534a9130f62578931a24477f317c17b42c71ffc3 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -149,6 +149,15 @@ static int ext4_meta_trans_blocks(struct inode *inode, int lblocks,
  */
 int ext4_inode_is_fast_symlink(struct inode *inode)
 {
+       if (!(EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL)) {
+               int ea_blocks = EXT4_I(inode)->i_file_acl ?
+                               EXT4_CLUSTER_SIZE(inode->i_sb) >> 9 : 0;
+
+               if (ext4_has_inline_data(inode))
+                       return 0;
+
+               return (S_ISLNK(inode->i_mode) && inode->i_blocks - ea_blocks == 0);
+       }
        return S_ISLNK(inode->i_mode) && inode->i_size &&
               (inode->i_size < EXT4_N_BLOCKS * 4);
 }