Revert "fs: don't allow splice read/write without explicit ops"
This reverts commit 36e2c7421f02a22f71c9283e55fdb672a9eb58e7.
Bug: 171770067
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Change-Id: Ibfd77d2f44380efa15edee606ff0d9d3dbeb48cb
diff --git a/fs/read_write.c b/fs/read_write.c
index 334252c60..b479ad8 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -1085,7 +1085,7 @@ ssize_t vfs_iter_write(struct file *file, struct iov_iter *iter, loff_t *ppos,
}
EXPORT_SYMBOL(vfs_iter_write);
-static ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
+ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
unsigned long vlen, loff_t *pos, rwf_t flags)
{
struct iovec iovstack[UIO_FASTIOV];
diff --git a/fs/splice.c b/fs/splice.c
index abb19d3..ce75aec 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -342,6 +342,89 @@ const struct pipe_buf_operations nosteal_pipe_buf_ops = {
};
EXPORT_SYMBOL(nosteal_pipe_buf_ops);
+static ssize_t kernel_readv(struct file *file, const struct kvec *vec,
+ unsigned long vlen, loff_t offset)
+{
+ mm_segment_t old_fs;
+ loff_t pos = offset;
+ ssize_t res;
+
+ old_fs = get_fs();
+ set_fs(KERNEL_DS);
+ /* The cast to a user pointer is valid due to the set_fs() */
+ res = vfs_readv(file, (const struct iovec __user *)vec, vlen, &pos, 0);
+ set_fs(old_fs);
+
+ return res;
+}
+
+static ssize_t default_file_splice_read(struct file *in, loff_t *ppos,
+ struct pipe_inode_info *pipe, size_t len,
+ unsigned int flags)
+{
+ struct kvec *vec, __vec[PIPE_DEF_BUFFERS];
+ struct iov_iter to;
+ struct page **pages;
+ unsigned int nr_pages;
+ unsigned int mask;
+ size_t offset, base, copied = 0;
+ ssize_t res;
+ int i;
+
+ if (pipe_full(pipe->head, pipe->tail, pipe->max_usage))
+ return -EAGAIN;
+
+ /*
+ * Try to keep page boundaries matching to source pagecache ones -
+ * it probably won't be much help, but...
+ */
+ offset = *ppos & ~PAGE_MASK;
+
+ iov_iter_pipe(&to, READ, pipe, len + offset);
+
+ res = iov_iter_get_pages_alloc(&to, &pages, len + offset, &base);
+ if (res <= 0)
+ return -ENOMEM;
+
+ nr_pages = DIV_ROUND_UP(res + base, PAGE_SIZE);
+
+ vec = __vec;
+ if (nr_pages > PIPE_DEF_BUFFERS) {
+ vec = kmalloc_array(nr_pages, sizeof(struct kvec), GFP_KERNEL);
+ if (unlikely(!vec)) {
+ res = -ENOMEM;
+ goto out;
+ }
+ }
+
+ mask = pipe->ring_size - 1;
+ pipe->bufs[to.head & mask].offset = offset;
+ pipe->bufs[to.head & mask].len -= offset;
+
+ for (i = 0; i < nr_pages; i++) {
+ size_t this_len = min_t(size_t, len, PAGE_SIZE - offset);
+ vec[i].iov_base = page_address(pages[i]) + offset;
+ vec[i].iov_len = this_len;
+ len -= this_len;
+ offset = 0;
+ }
+
+ res = kernel_readv(in, vec, nr_pages, *ppos);
+ if (res > 0) {
+ copied = res;
+ *ppos += res;
+ }
+
+ if (vec != __vec)
+ kfree(vec);
+out:
+ for (i = 0; i < nr_pages; i++)
+ put_page(pages[i]);
+ kvfree(pages);
+ iov_iter_advance(&to, copied); /* truncates and discards */
+ return res;
+}
+
/*
* Send 'sd->len' bytes to socket from 'sd->file' at position 'sd->pos'
* using sendpage(). Return the number of bytes sent.
@@ -725,6 +808,33 @@ iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
EXPORT_SYMBOL(iter_file_splice_write);
+static int write_pipe_buf(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
+ struct splice_desc *sd)
+{
+ int ret;
+ void *data;
+ loff_t tmp = sd->pos;
+
+ data = kmap(buf->page);
+ ret = __kernel_write(sd->u.file, data + buf->offset, sd->len, &tmp);
+ kunmap(buf->page);
+
+ return ret;
+}
+
+static ssize_t default_file_splice_write(struct pipe_inode_info *pipe,
+ struct file *out, loff_t *ppos,
+ size_t len, unsigned int flags)
+{
+ ssize_t ret;
+
+ ret = splice_from_pipe(pipe, out, ppos, len, flags, write_pipe_buf);
+ if (ret > 0)
+ *ppos += ret;
+
+ return ret;
+}
+
/**
* generic_splice_sendpage - splice data from a pipe to a socket
* @pipe: pipe to splice from
@@ -746,23 +856,15 @@ ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe, struct file *out,
EXPORT_SYMBOL(generic_splice_sendpage);
-static int warn_unsupported(struct file *file, const char *op)
-{
- pr_debug_ratelimited(
- "splice %s not supported for file %pD4 (pid: %d comm: %.20s)\n",
- op, file, current->pid, current->comm);
- return -EINVAL;
-}
-
/*
* Attempt to initiate a splice from pipe to file.
*/
static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
loff_t *ppos, size_t len, unsigned int flags)
{
- if (unlikely(!out->f_op->splice_write))
- return warn_unsupported(out, "write");
- return out->f_op->splice_write(pipe, out, ppos, len, flags);
+ if (out->f_op->splice_write)
+ return out->f_op->splice_write(pipe, out, ppos, len, flags);
+ return default_file_splice_write(pipe, out, ppos, len, flags);
}
/*
@@ -784,9 +886,9 @@ static long do_splice_to(struct file *in, loff_t *ppos,
if (unlikely(len > MAX_RW_COUNT))
len = MAX_RW_COUNT;
- if (unlikely(!in->f_op->splice_read))
- return warn_unsupported(in, "read");
- return in->f_op->splice_read(in, ppos, pipe, len, flags);
+ if (in->f_op->splice_read)
+ return in->f_op->splice_read(in, ppos, pipe, len, flags);
+ return default_file_splice_read(in, ppos, pipe, len, flags);
}
/**
diff --git a/include/linux/fs.h b/include/linux/fs.h
index fc0cf45..aba30ad 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1907,6 +1907,8 @@ ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
extern ssize_t vfs_read(struct file *, char __user *, size_t, loff_t *);
extern ssize_t vfs_write(struct file *, const char __user *, size_t, loff_t *);
+extern ssize_t vfs_readv(struct file *, const struct iovec __user *,
+ unsigned long, loff_t *, rwf_t);
extern ssize_t vfs_copy_file_range(struct file *, loff_t , struct file *,
loff_t, size_t, unsigned int);
extern ssize_t generic_copy_file_range(struct file *file_in, loff_t pos_in,
