1 files changed, 40 insertions, 18 deletions

diff --git a/fs/read_write.c b/fs/read_write.c
index 9ba495d5a29b..969a6d9c020b 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -31,39 +31,61 @@ const struct file_operations generic_ro_fops = {
 
 EXPORT_SYMBOL(generic_ro_fops);
 
+/**
+ * generic_file_llseek_unlocked - lockless generic llseek implementation
+ * @file:       file structure to seek on
+ * @offset:     file offset to seek to
+ * @origin:     type of seek
+ *
+ * Updates the file offset to the value specified by @offset and @origin.
+ * Locking must be provided by the caller.
+ */
 loff_t
 generic_file_llseek_unlocked(struct file *file, loff_t offset, int origin)
 {
-        loff_t retval;
         struct inode *inode = file->f_mapping->host;
 
         switch (origin) {
-                case SEEK_END:
-                        offset += inode->i_size;
-                        break;
-                case SEEK_CUR:
-                        offset += file->f_pos;
+        case SEEK_END:
+                offset += inode->i_size;
+                break;
+        case SEEK_CUR:
+                offset += file->f_pos;
+                break;
         }
-        retval = -EINVAL;
-        if (offset>=0 && offset<=inode->i_sb->s_maxbytes) {
-                /* Special lock needed here? */
-                if (offset != file->f_pos) {
-                        file->f_pos = offset;
-                        file->f_version = 0;
-                }
-                retval = offset;
+
+        if (offset < 0 || offset > inode->i_sb->s_maxbytes)
+                return -EINVAL;
+
+        /* Special lock needed here? */
+        if (offset != file->f_pos) {
+                file->f_pos = offset;
+                file->f_version = 0;
         }
-        return retval;
+
+        return offset;
 }
 EXPORT_SYMBOL(generic_file_llseek_unlocked);
 
+/**
+ * generic_file_llseek - generic llseek implementation for regular files
+ * @file:       file structure to seek on
+ * @offset:     file offset to seek to
+ * @origin:     type of seek
+ *
+ * This is a generic implemenation of ->llseek useable for all normal local
+ * filesystems.  It just updates the file offset to the value specified by
+ * @offset and @origin under i_mutex.
+ */
 loff_t generic_file_llseek(struct file *file, loff_t offset, int origin)
 {
-        loff_t n;
+        loff_t rval;
+
         mutex_lock(&file->f_dentry->d_inode->i_mutex);
-        n = generic_file_llseek_unlocked(file, offset, origin);
+        rval = generic_file_llseek_unlocked(file, offset, origin);
         mutex_unlock(&file->f_dentry->d_inode->i_mutex);
-        return n;
+
+        return rval;
 }
 EXPORT_SYMBOL(generic_file_llseek);