| Message ID | 3370085.1676475658@warthog.procyon.org.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | None | expand |
On Wed, 15 Feb 2023 at 16:41, David Howells <dhowells@redhat.com> wrote: > > How about the attached then? > > David > --- > overlayfs: Implement splice-read > > Implement splice-read for overlayfs by passing the request down a layer > rather than going through generic_file_splice_read() which is going to be > changed to assume that ->read_folio() is present on buffered files. Looks good. One more suggestion: add a vfs_splice() helper and use that from do_splice_to() as well. Thanks, Miklos
On Wed, Feb 15, 2023 at 04:50:04PM +0100, Miklos Szeredi wrote: > Looks good. One more suggestion: add a vfs_splice() helper and use > that from do_splice_to() as well. I really hate call_read_iter() etc. Please don't perpetuate that pattern.
Miklos Szeredi <miklos@szeredi.hu> wrote:
> Looks good.
Can I put that down as an Acked-by?
Thanks,
David
On Wed, Feb 15, 2023 at 03:53:23PM +0000, Matthew Wilcox wrote: > On Wed, Feb 15, 2023 at 04:50:04PM +0100, Miklos Szeredi wrote: > > Looks good. One more suggestion: add a vfs_splice() helper and use > > that from do_splice_to() as well. > > I really hate call_read_iter() etc. Please don't perpetuate that > pattern. I think it's time to kill it. I'll prepare a patch for it.
On Wed, 15 Feb 2023 at 16:53, Matthew Wilcox <willy@infradead.org> wrote: > > On Wed, Feb 15, 2023 at 04:50:04PM +0100, Miklos Szeredi wrote: > > Looks good. One more suggestion: add a vfs_splice() helper and use > > that from do_splice_to() as well. > > I really hate call_read_iter() etc. Please don't perpetuate that > pattern. I didn't suggest call_splice_read(). vfs_splice_read() would have the rw_verify_area() as well as the check for non-null ->splice_read(). Doing it that way from the start would have prevented two of the bugs that David introduced in the first version. Thanks, Miklos
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c index c9d0c362c7ef..72a545da51a2 100644 --- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -419,6 +419,37 @@ static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter) return ret; } +static ssize_t ovl_splice_read(struct file *in, loff_t *ppos, + struct pipe_inode_info *pipe, size_t len, + unsigned int flags) +{ + const struct cred *old_cred; + struct fd real; + ssize_t ret; + + ret = ovl_real_fdget(in, &real); + if (ret) + return ret; + + ret = -EINVAL; + if (!real.file->f_op->splice_read) + goto out_fdput; + + ret = rw_verify_area(READ, real.file, ppos, len); + if (unlikely(ret < 0)) + goto out_fdput; + + old_cred = ovl_override_creds(file_inode(in)->i_sb); + ret = real.file->f_op->splice_read(real.file, ppos, pipe, len, flags); + + revert_creds(old_cred); + ovl_file_accessed(in); +out_fdput: + fdput(real); + + return ret; +} + /* * Calling iter_file_splice_write() directly from overlay's f_op may deadlock * due to lock order inversion between pipe->mutex in iter_file_splice_write() @@ -695,7 +726,7 @@ const struct file_operations ovl_file_operations = { .fallocate = ovl_fallocate, .fadvise = ovl_fadvise, .flush = ovl_flush, - .splice_read = generic_file_splice_read, + .splice_read = ovl_splice_read, .splice_write = ovl_splice_write, .copy_file_range = ovl_copy_file_range,
How about the attached then? David --- overlayfs: Implement splice-read Implement splice-read for overlayfs by passing the request down a layer rather than going through generic_file_splice_read() which is going to be changed to assume that ->read_folio() is present on buffered files. Signed-off-by: David Howells <dhowells@redhat.com> cc: Christoph Hellwig <hch@lst.de> cc: Jens Axboe <axboe@kernel.dk> cc: Al Viro <viro@zeniv.linux.org.uk> cc: John Hubbard <jhubbard@nvidia.com> cc: David Hildenbrand <david@redhat.com> cc: Matthew Wilcox <willy@infradead.org> cc: Miklos Szeredi <miklos@szeredi.hu> cc: linux-unionfs@vger.kernel.org cc: linux-block@vger.kernel.org cc: linux-fsdevel@vger.kernel.org cc: linux-mm@kvack.org --- Notes: ver #15) - Remove redundant FMODE_CAN_ODIRECT check on real file. - Do rw_verify_area() on the real file, not the overlay file. - Fix a file leak. fs/overlayfs/file.c | 33 ++++++++++++++++++++++++++++++++- 1 file changed, 32 insertions(+), 1 deletion(-)