[PATCH 01/15] Introduce noop_llseek()

[Jan Blunck <jblunck@suse.de>]

The noop_llseek() is a llseek() operation that filesystems can use that
don't want to support seeking (leave the file->f_pos untouched) but still
want to let the syscall itself to succeed.

Signed-off-by: Jan Blunck <jblunck@suse.de>
---
 fs/read_write.c    |    6 ++++++
 include/linux/fs.h |    1 +
 2 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/fs/read_write.c b/fs/read_write.c
index 3ac2898..7a01d11 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -97,6 +97,12 @@ loff_t generic_file_llseek(struct file *file, loff_t offset, int origin)
 }
 EXPORT_SYMBOL(generic_file_llseek);
 
+loff_t noop_llseek(struct file *file, loff_t offset, int origin)
+{
+	return file->f_pos;
+}
+EXPORT_SYMBOL(noop_llseek);
+
 loff_t no_llseek(struct file *file, loff_t offset, int origin)
 {
 	return -ESPIPE;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 2620a8c..0a0c1f4 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2237,6 +2237,7 @@ extern long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
 
 extern void
 file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping);
+extern loff_t noop_llseek(struct file *file, loff_t offset, int origin);
 extern loff_t no_llseek(struct file *file, loff_t offset, int origin);
 extern loff_t generic_file_llseek(struct file *file, loff_t offset, int origin);
 extern loff_t generic_file_llseek_unlocked(struct file *file, loff_t offset,
-- 
1.6.4.2