[PATCH v21 20/30] nfs: Provide a splice-read stub

David Howells
2023-05-20T00:02:03Z

Provide a splice_read stub for NFS. This locks the inode around
filemap_splice_read() and revalidates the mapping. Splicing from direct
I/O is handled by the caller.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Christoph Hellwig <hch@lst.de>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: Jens Axboe <axboe@kernel.dk>
cc: Trond Myklebust <trond.myklebust@hammerspace.com>
cc: Anna Schumaker <anna@kernel.org>
cc: linux-nfs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
cc: linux-block@vger.kernel.org
cc: linux-mm@kvack.org
---

Notes:
ver #21)
- Fix pos -> ppos in dprintk().

fs/nfs/file.c | 23 ++++++++++++++++++++++-
fs/nfs/internal.h | 2 ++
fs/nfs/nfs4file.c | 2 +-
3 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index f0edf5a36237..f5615fdaa9ed 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -178,6 +178,27 @@ nfs_file_read(struct kiocb *iocb, struct iov_iter *to)
}
EXPORT_SYMBOL_GPL(nfs_file_read);

+ssize_t
+nfs_file_splice_read(struct file *in, loff_t *ppos, struct pipe_inode_info *pipe,
+ size_t len, unsigned int flags)
+{
+ struct inode *inode = file_inode(in);
+ ssize_t result;
+
+ dprintk("NFS: splice_read(%pD2, %zu@%lu)\n", in, len, *ppos);
+
+ nfs_start_io_read(inode);
+ result = nfs_revalidate_mapping(inode, in->f_mapping);
+ if (!result) {
+ result = filemap_splice_read(in, ppos, pipe, len, flags);
+ if (result > 0)
+ nfs_add_stats(inode, NFSIOS_NORMALREADBYTES, result);
+ }
+ nfs_end_io_read(inode);
+ return result;
+}
+EXPORT_SYMBOL_GPL(nfs_file_splice_read);
+
int
nfs_file_mmap(struct file * file, struct vm_area_struct * vma)
{
@@ -879,7 +900,7 @@ const struct file_operations nfs_file_operations = {
.fsync = nfs_file_fsync,
.lock = nfs_lock,
.flock = nfs_flock,
- .splice_read = generic_file_splice_read,
+ .splice_read = nfs_file_splice_read,
.splice_write = iter_file_splice_write,
.check_flags = nfs_check_flags,
.setlease = simple_nosetlease,
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 3cc027d3bd58..b5f21d35d30e 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -416,6 +416,8 @@ static inline __u32 nfs_access_xattr_mask(const struct nfs_server *server)
int nfs_file_fsync(struct file *file, loff_t start, loff_t end, int datasync);
loff_t nfs_file_llseek(struct file *, loff_t, int);
ssize_t nfs_file_read(struct kiocb *, struct iov_iter *);
+ssize_t nfs_file_splice_read(struct file *in, loff_t *ppos, struct pipe_inode_info *pipe,
+ size_t len, unsigned int flags);
int nfs_file_mmap(struct file *, struct vm_area_struct *);
ssize_t nfs_file_write(struct kiocb *, struct iov_iter *);
int nfs_file_release(struct inode *, struct file *);
diff --git a/fs/nfs/nfs4file.c b/fs/nfs/nfs4file.c
index 2563ed8580f3..4aeadd6e1a6d 100644
--- a/fs/nfs/nfs4file.c
+++ b/fs/nfs/nfs4file.c
@@ -454,7 +454,7 @@ const struct file_operations nfs4_file_operations = {
.fsync = nfs_file_fsync,
.lock = nfs_lock,
.flock = nfs_flock,
- .splice_read = generic_file_splice_read,
+ .splice_read = nfs_file_splice_read,
.splice_write = iter_file_splice_write,
.check_flags = nfs_check_flags,
.setlease = nfs4_setlease,