[PATCH RESEND] vfs: Return EINVAL for default SEEK_HOLE, SEEK_DATA implementation

Jan Kara
2014-10-10T14:24:11Z

Generic implementation of SEEK_HOLE & SEEK_DATA in
generic_file_llseek_size() and default_llseek() behaved as if everything
within i_size is data and everything beyond i_size is a hole. That makes
sense at the first sight (and definitely is a valid implementation of
the spec) but at the second sight it isn't very useful. If anyone
bothers with looking for holes / data, he should be better told we don't
really know so that he can fall back to his chosen backup strategy
(think of e.g. cp(1)).

This is a userspace API change however the kernel interface is there
only for two years so hopefully userspace is still prepared to handle
EINVAL return value.

Signed-off-by: Jan Kara <jack@suse.cz>
---
fs/read_write.c | 38 ++------------------------------------
1 file changed, 2 insertions(+), 36 deletions(-)

Al, what do you think about this change?

diff --git a/fs/read_write.c b/fs/read_write.c
index edc5746a902a..71525d75742f 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -111,22 +111,8 @@ generic_file_llseek_size(struct file *file, loff_t offset, int whence,
spin_unlock(&file->f_lock);
return offset;
case SEEK_DATA:
- /*
- * In the generic case the entire file is data, so as long as
- * offset isn't at the end of the file then the offset is data.
- */
- if (offset >= eof)
- return -ENXIO;
- break;
case SEEK_HOLE:
- /*
- * There is a virtual hole at the end of the file, so as long as
- * offset isn't i_size or larger, return i_size.
- */
- if (offset >= eof)
- return -ENXIO;
- offset = eof;
- break;
+ return -EINVAL;
}

return vfs_setpos(file, offset, maxsize);
@@ -214,28 +200,8 @@ loff_t default_llseek(struct file *file, loff_t offset, int whence)
offset += file->f_pos;
break;
case SEEK_DATA:
- /*
- * In the generic case the entire file is data, so as
- * long as offset isn't at the end of the file then the
- * offset is data.
- */
- if (offset >= inode->i_size) {
- retval = -ENXIO;
- goto out;
- }
- break;
case SEEK_HOLE:
- /*
- * There is a virtual hole at the end of the file, so
- * as long as offset isn't i_size or larger, return
- * i_size.
- */
- if (offset >= inode->i_size) {
- retval = -ENXIO;
- goto out;
- }
- offset = inode->i_size;
- break;
+ return -EINVAL;
}
retval = -EINVAL;
if (offset >= 0 || unsigned_offsets(file)) {