| Message ID | 20230520000049.2226926-11-dhowells@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | splice: Kill ITER_PIPE | expand |
[Cc Amir as well] On Sat, May 20, 2023 at 01:00:29AM +0100, David Howells wrote: > 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 > --- Acked-by: Christian Brauner <brauner@kernel.org> > > Notes: > ver #17) > - Use vfs_splice_read() helper rather than open-coding checks. > > 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 | 23 ++++++++++++++++++++++- > 1 file changed, 22 insertions(+), 1 deletion(-) > > diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c > index 7c04f033aadd..86197882ff35 100644 > --- a/fs/overlayfs/file.c > +++ b/fs/overlayfs/file.c > @@ -419,6 +419,27 @@ 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; > + > + old_cred = ovl_override_creds(file_inode(in)->i_sb); > + ret = vfs_splice_read(real.file, ppos, pipe, len, flags); > + revert_creds(old_cred); > + ovl_file_accessed(in); > + > + 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 +716,7 @@ 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, >
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c index 7c04f033aadd..86197882ff35 100644 --- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -419,6 +419,27 @@ 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; + + old_cred = ovl_override_creds(file_inode(in)->i_sb); + ret = vfs_splice_read(real.file, ppos, pipe, len, flags); + revert_creds(old_cred); + ovl_file_accessed(in); + + 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 +716,7 @@ 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,
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 #17) - Use vfs_splice_read() helper rather than open-coding checks. 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 | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-)