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@xxxxxx>
Index: linux-2.6/fs/read_write.c
===================================================================
--- linux-2.6.orig/fs/read_write.c 2008-07-21 11:41:14.000000000 -0300
+++ linux-2.6/fs/read_write.c 2008-08-11 10:00:55.000000000 -0300
@@ -31,39 +31,61 @@ const struct file_operations generic_ro_
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);
--
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