diff options
| -rw-r--r-- | fs/read_write.c | 17 | ||||
| -rw-r--r-- | include/linux/fs.h | 1 |
2 files changed, 18 insertions, 0 deletions
diff --git a/fs/read_write.c b/fs/read_write.c index 113386d..9c04852 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -97,6 +97,23 @@ loff_t generic_file_llseek(struct file *file, loff_t offset, int origin) } EXPORT_SYMBOL(generic_file_llseek); +/** + * noop_llseek - No Operation Performed llseek implementation + * @file: file structure to seek on + * @offset: file offset to seek to + * @origin: type of seek + * + * This is an implementation of ->llseek useable for the rare special case when + * userspace expects the seek to succeed but the (device) file is actually not + * able to perform the seek. In this case you use noop_llseek() instead of + * falling back to the default implementation of ->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 b336cb9..9682d52 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2228,6 +2228,7 @@ 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, |