3 files changed, 45 insertions, 2 deletions

diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c
index 374510f72baa..ece76fb6a40c 100644
--- a/fs/ext4/dir.c
+++ b/fs/ext4/dir.c
@@ -39,7 +39,7 @@ static int ext4_release_dir(struct inode *inode,
                                 struct file *filp);
 
 const struct file_operations ext4_dir_operations = {
-        .llseek         = generic_file_llseek,
+        .llseek         = ext4_llseek,
         .read           = generic_read_dir,
         .readdir        = ext4_readdir,         /* we take BKL. needed?*/
         .unlocked_ioctl = ext4_ioctl,
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 4c5fe37b237d..e1c01552a3df 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2006,6 +2006,7 @@ extern const struct file_operations ext4_dir_operations;
 /* file.c */
 extern const struct inode_operations ext4_file_inode_operations;
 extern const struct file_operations ext4_file_operations;
+extern loff_t ext4_llseek(struct file *file, loff_t offset, int origin);
 
 /* namei.c */
 extern const struct inode_operations ext4_dir_inode_operations;
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index ee92b66d4558..5a5c55ddceef 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -130,8 +130,50 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
         return dquot_file_open(inode, filp);
 }
 
+/*
+ * ext4_llseek() copied from generic_file_llseek() to handle both
+ * block-mapped and extent-mapped maxbytes values. This should
+ * otherwise be identical with generic_file_llseek().
+ */
+loff_t ext4_llseek(struct file *file, loff_t offset, int origin)
+{
+        struct inode *inode = file->f_mapping->host;
+        loff_t maxbytes;
+
+        if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
+                maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
+        else
+                maxbytes = inode->i_sb->s_maxbytes;
+        mutex_lock(&inode->i_mutex);
+        switch (origin) {
+        case SEEK_END:
+                offset += inode->i_size;
+                break;
+        case SEEK_CUR:
+                if (offset == 0) {
+                        mutex_unlock(&inode->i_mutex);
+                        return file->f_pos;
+                }
+                offset += file->f_pos;
+                break;
+        }
+
+        if (offset < 0 || offset > maxbytes) {
+                mutex_unlock(&inode->i_mutex);
+                return -EINVAL;
+        }
+
+        if (offset != file->f_pos) {
+                file->f_pos = offset;
+                file->f_version = 0;
+        }
+        mutex_unlock(&inode->i_mutex);
+
+        return offset;
+}
+
 const struct file_operations ext4_file_operations = {
-        .llseek         = generic_file_llseek,
+        .llseek         = ext4_llseek,
         .read           = do_sync_read,
         .write          = do_sync_write,
         .aio_read       = generic_file_aio_read,