Darrick J. Wong
2018-Oct-10 15:50 UTC
[Ocfs2-devel] [PATCH 14/25] vfs: make remap_file_range functions take and return bytes completed
On Wed, Oct 10, 2018 at 09:47:00AM +0300, Amir Goldstein wrote:> On Wed, Oct 10, 2018 at 3:14 AM Darrick J. Wong <darrick.wong at oracle.com> wrote: > > > > From: Darrick J. Wong <darrick.wong at oracle.com> > > > > Change the remap_file_range functions to take a number of bytes to > > operate upon and return the number of bytes they operated on. This is a > > requirement for allowing fs implementations to return short clone/dedupe > > results to the user, which will enable us to obey resource limits in a > > graceful manner. > > > > A subsequent patch will enable copy_file_range to signal to the > > ->clone_file_range implementation that it can handle a short length, > > which will be returned in the function's return value. Neither clone > > ioctl can take advantage of this, alas. > > > > Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com> > > --- > [...] > > @@ -141,8 +142,8 @@ static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len) > > } > > > > /* Try to use clone_file_range to clone up within the same fs */ > > - error = do_clone_file_range(old_file, 0, new_file, 0, len); > > - if (!error) > > + cloned = do_clone_file_range(old_file, 0, new_file, 0, len); > > + if (cloned == len) > > goto out; > > /* Couldn't clone, so now we try to copy the data */ > > error = 0; > > This error = 0 not needed anymore, but not a big deal...Fixed.> > diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c > > index 693bd0620a81..c8c890c22898 100644 > > --- a/fs/overlayfs/file.c > > +++ b/fs/overlayfs/file.c > > @@ -434,14 +434,14 @@ enum ovl_copyop { > > OVL_DEDUPE, > > }; > > > > -static ssize_t ovl_copyfile(struct file *file_in, loff_t pos_in, > > +static loff_t ovl_copyfile(struct file *file_in, loff_t pos_in, > > struct file *file_out, loff_t pos_out, > > - u64 len, unsigned int flags, enum ovl_copyop op) > > + loff_t len, unsigned int flags, enum ovl_copyop op) > > { > > struct inode *inode_out = file_inode(file_out); > > struct fd real_in, real_out; > > const struct cred *old_cred; > > - ssize_t ret; > > + loff_t ret; > > > > ret = ovl_real_fdget(file_out, &real_out); > > if (ret) > > @@ -489,9 +489,9 @@ static ssize_t ovl_copy_file_range(struct file *file_in, loff_t pos_in, > > OVL_COPY); > > } > > > > -static int ovl_remap_file_range(struct file *file_in, loff_t pos_in, > > - struct file *file_out, loff_t pos_out, > > - u64 len, unsigned int flags) > > +static loff_t ovl_remap_file_range(struct file *file_in, loff_t pos_in, > > + struct file *file_out, loff_t pos_out, > > + loff_t len, unsigned int flags) > > { > > enum ovl_copyop op; > > > > diff --git a/fs/read_write.c b/fs/read_write.c > > index 917934770b08..f43b0620afd4 100644 > > --- a/fs/read_write.c > > +++ b/fs/read_write.c > > @@ -1589,10 +1589,13 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, > > * more efficient if both clone and copy are supported (e.g. NFS). > > */ > > if (file_in->f_op->remap_file_range) { > > - ret = file_in->f_op->remap_file_range(file_in, pos_in, > > - file_out, pos_out, len, 0); > > - if (ret == 0) { > > - ret = len; > > + s64 cloned; > > loff_t?Fixed.> > + > > + cloned = file_in->f_op->remap_file_range(file_in, pos_in, > > + file_out, pos_out, > > + min_t(loff_t, MAX_RW_COUNT, len), 0); > > + if (cloned >= 0) { > > + ret = cloned; > > goto done; > > } > > } > > Commit message wasn't clear enough on the behavior of copy_file_range() > before and after the patch IMO. Maybe it would be better to pospone this > semantic change to the RFR_SHORTEN patch and keep if (cloned == len) > in this patch?There shouldn't be any behavior change here -- all implementations return a negative error code or the length that was passed in. I'll clarify that in the commit message. --D> Thanks, > Amir.