fs: do not compare against ->llseek

Now vfs_llseek() can simply check for FMODE_LSEEK; if it's set,
we know that ->llseek() won't be NULL and if it's not we should
just fail with -ESPIPE.

A couple of other places where we used to check for special
values of ->llseek() (somewhat inconsistently) switched to
checking FMODE_LSEEK.

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

diff --git a/fs/coredump.c b/fs/coredump.c
index ebc43f9..9f4aae2 100644 (file)
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -816,9 +816,9 @@ static int __dump_skip(struct coredump_params *cprm, size_t nr)
 {
        static char zeroes[PAGE_SIZE];
        struct file *file = cprm->file;
-       if (file->f_op->llseek && file->f_op->llseek != no_llseek) {
+       if (file->f_mode & FMODE_LSEEK) {
                if (dump_interrupted() ||
-                   file->f_op->llseek(file, nr, SEEK_CUR) < 0)
+                   vfs_llseek(file, nr, SEEK_CUR) < 0)
                        return 0;
                cprm->pos += nr;
                return 1;

diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index 714ec56..022606c 100644 (file)
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -226,8 +226,7 @@ static int ovl_copy_up_data(struct ovl_fs *ofs, struct path *old,
        /* Couldn't clone, so now we try to copy the data */
 
        /* Check if lower fs supports seek operation */
-       if (old_file->f_mode & FMODE_LSEEK &&
-           old_file->f_op->llseek)
+       if (old_file->f_mode & FMODE_LSEEK)
                skip_hole = true;
 
        while (len) {

diff --git a/fs/read_write.c b/fs/read_write.c
index b1b1cdf..d94b6db 100644 (file)
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -290,14 +290,9 @@ EXPORT_SYMBOL(default_llseek);
 
 loff_t vfs_llseek(struct file *file, loff_t offset, int whence)
 {
-       loff_t (*fn)(struct file *, loff_t, int);
-
-       fn = no_llseek;
-       if (file->f_mode & FMODE_LSEEK) {
-               if (file->f_op->llseek)
-                       fn = file->f_op->llseek;
-       }
-       return fn(file, offset, whence);
+       if (!(file->f_mode & FMODE_LSEEK))
+               return -ESPIPE;
+       return file->f_op->llseek(file, offset, whence);
 }
 EXPORT_SYMBOL(vfs_llseek);