afs: Provide a splice-read wrapper

Provide a splice_read wrapper for AFS to call afs_validate() before going
into generic_file_splice_read() so that we're likely to have a callback
promise from the server.

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: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
cc: linux-fsdevel@vger.kernel.org
cc: linux-block@vger.kernel.org
cc: linux-mm@kvack.org
Link: https://lore.kernel.org/r/20230522135018.2742245-16-dhowells@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/afs/file.c b/fs/afs/file.c
index 719b313..d8a6b09 100644 (file)
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -25,6 +25,9 @@ static void afs_invalidate_folio(struct folio *folio, size_t offset,
 static bool afs_release_folio(struct folio *folio, gfp_t gfp_flags);
 
 static ssize_t afs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter);
+static ssize_t afs_file_splice_read(struct file *in, loff_t *ppos,
+                                   struct pipe_inode_info *pipe,
+                                   size_t len, unsigned int flags);
 static void afs_vm_open(struct vm_area_struct *area);
 static void afs_vm_close(struct vm_area_struct *area);
 static vm_fault_t afs_vm_map_pages(struct vm_fault *vmf, pgoff_t start_pgoff, pgoff_t end_pgoff);
@@ -36,7 +39,7 @@ const struct file_operations afs_file_operations = {
        .read_iter      = afs_file_read_iter,
        .write_iter     = afs_file_write,
        .mmap           = afs_file_mmap,
-       .splice_read    = generic_file_splice_read,
+       .splice_read    = afs_file_splice_read,
        .splice_write   = iter_file_splice_write,
        .fsync          = afs_fsync,
        .lock           = afs_lock,
@@ -587,3 +590,18 @@ static ssize_t afs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
 
        return generic_file_read_iter(iocb, iter);
 }
+
+static ssize_t afs_file_splice_read(struct file *in, loff_t *ppos,
+                                   struct pipe_inode_info *pipe,
+                                   size_t len, unsigned int flags)
+{
+       struct afs_vnode *vnode = AFS_FS_I(file_inode(in));
+       struct afs_file *af = in->private_data;
+       int ret;
+
+       ret = afs_validate(vnode, af->key);
+       if (ret < 0)
+               return ret;
+
+       return generic_file_splice_read(in, ppos, pipe, len, flags);
+}