Darrick J. Wong
2018-Oct-05 21:47 UTC
[Ocfs2-devel] [PATCH 08/15] vfs: change clone and dedupe range function pointers to return bytes completed
On Fri, Oct 05, 2018 at 11:06:54AM +0300, Amir Goldstein wrote:> On Fri, Oct 5, 2018 at 3:46 AM Darrick J. Wong <darrick.wong at oracle.com> wrote: > > > > From: Darrick J. Wong <darrick.wong at oracle.com> > > > > Change the clone_file_range and dedupe_file_range functions to return > > the number of bytes they operated on. This is the precursor to allowing > > fs implementations to return short clone/dedupe results to the user, > > which will enable us to obey resource limits in a graceful manner. > > > > Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com> > > --- > > [...] > > > diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c > > index aeaefd2a551b..6d792d817538 100644 > > --- a/fs/overlayfs/file.c > > +++ b/fs/overlayfs/file.c > > @@ -487,16 +487,21 @@ static ssize_t ovl_copy_file_range(struct file *file_in, loff_t pos_in, > > OVL_COPY); > > } > > > > -static int ovl_clone_file_range(struct file *file_in, loff_t pos_in, > > +static s64 ovl_clone_file_range(struct file *file_in, loff_t pos_in, > > struct file *file_out, loff_t pos_out, u64 len) > > { > > - return ovl_copyfile(file_in, pos_in, file_out, pos_out, len, 0, > > - OVL_CLONE); > > + int ret; > > + > > + ret = ovl_copyfile(file_in, pos_in, file_out, pos_out, len, 0, > > + OVL_CLONE); > > + return ret < 0 ? ret : len; > > } > > > > -static int ovl_dedupe_file_range(struct file *file_in, loff_t pos_in, > > +static s64 ovl_dedupe_file_range(struct file *file_in, loff_t pos_in, > > struct file *file_out, loff_t pos_out, u64 len) > > { > > + int ret; > > + > > /* > > * Don't copy up because of a dedupe request, this wouldn't make sense > > * most of the time (data would be duplicated instead of deduplicated). > > @@ -505,8 +510,9 @@ static int ovl_dedupe_file_range(struct file *file_in, loff_t pos_in, > > !ovl_inode_upper(file_inode(file_out))) > > return -EPERM; > > > > - return ovl_copyfile(file_in, pos_in, file_out, pos_out, len, 0, > > - OVL_DEDUPE); > > + ret = ovl_copyfile(file_in, pos_in, file_out, pos_out, len, 0, > > + OVL_DEDUPE); > > + return ret < 0 ? ret : len; > > } > > > > This is not pretty at all. > You are blocking the propagation of partial dedupe/clone result > of files that are accessed via overlay over xfs. > > Please extend the interface change to the vfs helpers > (i.e. vfs_clone_file_range()) and then the change above is not needed. > > Of course you would need to change the 3 callers of > vfs_clone_file_range() that expect 0 is ok.Ok, I'll plumb the bytes-finished return value all the way through the internal APIs.> Please take a look at commit > a725356b6659 ("vfs: swap names of {do,vfs}_clone_file_range()") > > That was just merged for rc7. > > I do apologize for the churn, but it's a semantic mistake that > I made that needed fixing, so please rebase your work on top > of that and take care not to trip over it.Err... ok. That makes working on this a little messy, we'll see if I can get this mess rebased in time for 5.0.> ioctl_file_clone() and ovl_copy_up_data() just need to interpret > positive return value correctly. > nfsd4_clone_file_range() should have the same return value as > vfs_clone_file_range() to be interpreted in nfsd4_clone(), following > same practice as nfsd4_copy_file_range(). > > [...] > > > diff --git a/include/linux/fs.h b/include/linux/fs.h > > index 2a4141d36ebf..e5755340e825 100644 > > --- a/include/linux/fs.h > > +++ b/include/linux/fs.h > > @@ -1759,10 +1759,12 @@ struct file_operations { > > #endif > > ssize_t (*copy_file_range)(struct file *, loff_t, struct file *, > > loff_t, size_t, unsigned int); > > - int (*clone_file_range)(struct file *, loff_t, struct file *, loff_t, > > - u64); > > - int (*dedupe_file_range)(struct file *, loff_t, struct file *, loff_t, > > - u64); > > + s64 (*clone_file_range)(struct file *file_in, loff_t pos_in, > > + struct file *file_out, loff_t pos_out, > > + u64 count); > > + s64 (*dedupe_file_range)(struct file *file_in, loff_t pos_in, > > + struct file *file_out, loff_t pos_out, > > + u64 count); > > Matthew has objected a similar interface change when it was proposed by Miklos: > https://marc.info/?l=linux-fsdevel&m=152570317110292&w=2 > https://marc.info/?l=linux-fsdevel&m=152569298704781&w=2 > > He claimed that the interface should look like this: > + loff_t (*dedupe_file_range)(struct file *src, loff_t src_off, > + struct file *dst, loff_t dst_off, loff_t len);I don't really like loff_t (why does the typename for a size include "offset" in the name??) but I guess that's not horrible. I've never liked how functions take size_t (unsigned) but return ssize_t (signed) anyway. --D> Thanks, > Amir.