fs: remove no_llseek

Now that all callers of ->llseek are going through vfs_llseek(), we
don't gain anything by keeping no_llseek around. Nothing actually calls
it and setting ->llseek to no_lseek is completely equivalent to
leaving it NULL.

Longer term (== by the end of merge window) we want to remove all such
intializations.  To simplify the merge window this commit does *not*
touch initializers - it only defines no_llseek as NULL (and simplifies
the tests on file opening).

At -rc1 we'll need do a mechanical removal of no_llseek -

git grep -l -w no_llseek | grep -v porting.rst | while read i; do
	sed -i '/\<no_llseek\>/d' $i
done
would do it.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 8 insertions, 0 deletions

diff --git a/Documentation/filesystems/porting.rst b/Documentation/filesystems/porting.rst
index 2e0e4f0e0c6f..aee9aaf9f3df 100644
--- a/Documentation/filesystems/porting.rst
+++ b/Documentation/filesystems/porting.rst
@@ -914,3 +914,11 @@ Calling conventions for file_open_root() changed; now it takes struct path *
 instead of passing mount and dentry separately.  For callers that used to
 pass <mnt, mnt->mnt_root> pair (i.e. the root of given mount), a new helper
 is provided - file_open_root_mnt().  In-tree users adjusted.
+
+---
+
+**mandatory**
+
+no_llseek is gone; don't set .llseek to that - just leave it NULL instead.
+Checks for "does that file have llseek(2), or should it fail with ESPIPE"
+should be done by looking at FMODE_LSEEK in file->f_mode.