[PATCH] generic_file_llseek tidyups

Add kerneldoc for generic_file_llseek and generic_file_llseek_unlocked,
use sane variable names and unclutter the code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/read_write.c b/fs/read_write.c
index 9ba495d5a29b26d9493eea556ccd0992deb68829..969a6d9c020ba01644578b04c86043b15e98b53a 100644 (file)
--- 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);