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authorChristoph Hellwig <hch@lst.de>2008-08-11 15:37:17 +0200
committerAl Viro <viro@zeniv.linux.org.uk>2008-10-23 05:12:59 -0400
commit3a8cff4f026c0b98bee6291eb28d4df42feb76dc (patch)
tree809078b0768e3b30b4e7ccbbd2eca7fd72f70158 /fs/read_write.c
parenta518ab9329041411526ab8e05edfda7e2715244f (diff)
downloadlinux-3a8cff4f026c0b98bee6291eb28d4df42feb76dc.tar.gz
[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>
Diffstat (limited to 'fs/read_write.c')
-rw-r--r--fs/read_write.c58
1 files changed, 40 insertions, 18 deletions
diff --git a/fs/read_write.c b/fs/read_write.c
index 9ba495d5a29..969a6d9c020 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);