ext4: Do not try to validate extents on special files

The EXTENTS_FL flag should never be set on special files, but if it
is, don't bother trying to validate that the extents tree is valid,
since only files, directories, and non-fast symlinks will ever have an
extent data structure.  We perhaps should flag the filesystem as being
corrupted if we see a special file (named pipes, device nodes, Unix
domain sockets, etc.) with the EXTENTS_FL flag, but e2fsck doesn't
currently check this case, so we'll just ignore this for now, since
it's harmless.

Without this fix, a special device with the extents flag is flagged as
an error by the kernel, so it is impossible to access or delete the
inode, but e2fsck doesn't see it as a problem, leading to
confused/frustrated users.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 6 insertions, 2 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 11460037ea9d..e91f978c7f12 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4407,6 +4407,7 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
                         (__u64)(le32_to_cpu(raw_inode->i_version_hi)) << 32;
         }
 
+        ret = 0;
         if (ei->i_file_acl &&
             ((ei->i_file_acl < 
               (le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block) +
@@ -4418,8 +4419,11 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
                 ret = -EIO;
                 goto bad_inode;
         } else if (ei->i_flags & EXT4_EXTENTS_FL) {
-                /* Validate extent which is part of inode */
-                ret = ext4_ext_check_inode(inode);
+                if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
+                    (S_ISLNK(inode->i_mode) &&
+                     !ext4_inode_is_fast_symlink(inode)))
+                        /* Validate extent which is part of inode */
+                        ret = ext4_ext_check_inode(inode);
         } else if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
                    (S_ISLNK(inode->i_mode) &&
                     !ext4_inode_is_fast_symlink(inode))) {