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// SPDX-License-Identifier: GPL-2.0-or-later
/* Unbuffered and direct write support.
*
* Copyright (C) 2023 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/export.h>
#include <linux/uio.h>
#include "internal.h"
/*
* Perform an unbuffered write where we may have to do an RMW operation on an
* encrypted file. This can also be used for direct I/O writes.
*/
ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *iter,
struct netfs_group *netfs_group)
{
struct netfs_io_request *wreq;
unsigned long long start = iocb->ki_pos;
unsigned long long end = start + iov_iter_count(iter);
ssize_t ret, n;
size_t len = iov_iter_count(iter);
bool async = !is_sync_kiocb(iocb);
_enter("");
/* We're going to need a bounce buffer if what we transmit is going to
* be different in some way to the source buffer, e.g. because it gets
* encrypted/compressed or because it needs expanding to a block size.
*/
// TODO
_debug("uw %llx-%llx", start, end);
wreq = netfs_create_write_req(iocb->ki_filp->f_mapping, iocb->ki_filp, start,
iocb->ki_flags & IOCB_DIRECT ?
NETFS_DIO_WRITE : NETFS_UNBUFFERED_WRITE);
if (IS_ERR(wreq))
return PTR_ERR(wreq);
wreq->io_streams[0].avail = true;
trace_netfs_write(wreq, (iocb->ki_flags & IOCB_DIRECT ?
netfs_write_trace_dio_write :
netfs_write_trace_unbuffered_write));
{
/* If this is an async op and we're not using a bounce buffer,
* we have to save the source buffer as the iterator is only
* good until we return. In such a case, extract an iterator
* to represent as much of the the output buffer as we can
* manage. Note that the extraction might not be able to
* allocate a sufficiently large bvec array and may shorten the
* request.
*/
if (user_backed_iter(iter)) {
n = netfs_extract_user_iter(iter, len, &wreq->buffer.iter, 0);
if (n < 0) {
ret = n;
goto error_put;
}
wreq->direct_bv = (struct bio_vec *)wreq->buffer.iter.bvec;
wreq->direct_bv_count = n;
wreq->direct_bv_unpin = iov_iter_extract_will_pin(iter);
} else {
/* If this is a kernel-generated async DIO request,
* assume that any resources the iterator points to
* (eg. a bio_vec array) will persist till the end of
* the op.
*/
wreq->buffer.iter = *iter;
}
}
__set_bit(NETFS_RREQ_USE_IO_ITER, &wreq->flags);
if (async)
__set_bit(NETFS_RREQ_OFFLOAD_COLLECTION, &wreq->flags);
/* Copy the data into the bounce buffer and encrypt it. */
// TODO
/* Dispatch the write. */
__set_bit(NETFS_RREQ_UPLOAD_TO_SERVER, &wreq->flags);
if (async)
wreq->iocb = iocb;
wreq->len = iov_iter_count(&wreq->buffer.iter);
ret = netfs_unbuffered_write(wreq, is_sync_kiocb(iocb), wreq->len);
if (ret < 0) {
_debug("begin = %zd", ret);
goto out;
}
if (!async) {
ret = netfs_wait_for_write(wreq);
if (ret > 0)
iocb->ki_pos += ret;
} else {
ret = -EIOCBQUEUED;
}
out:
netfs_put_request(wreq, netfs_rreq_trace_put_return);
return ret;
error_put:
netfs_put_failed_request(wreq);
return ret;
}
EXPORT_SYMBOL(netfs_unbuffered_write_iter_locked);
/**
* netfs_unbuffered_write_iter - Unbuffered write to a file
* @iocb: IO state structure
* @from: iov_iter with data to write
*
* Do an unbuffered write to a file, writing the data directly to the server
* and not lodging the data in the pagecache.
*
* Return:
* * Negative error code if no data has been written at all of
* vfs_fsync_range() failed for a synchronous write
* * Number of bytes written, even for truncated writes
*/
ssize_t netfs_unbuffered_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
struct file *file = iocb->ki_filp;
struct address_space *mapping = file->f_mapping;
struct inode *inode = mapping->host;
struct netfs_inode *ictx = netfs_inode(inode);
ssize_t ret;
loff_t pos = iocb->ki_pos;
unsigned long long end = pos + iov_iter_count(from) - 1;
_enter("%llx,%zx,%llx", pos, iov_iter_count(from), i_size_read(inode));
if (!iov_iter_count(from))
return 0;
trace_netfs_write_iter(iocb, from);
netfs_stat(&netfs_n_wh_dio_write);
ret = netfs_start_io_direct(inode);
if (ret < 0)
return ret;
ret = generic_write_checks(iocb, from);
if (ret <= 0)
goto out;
ret = file_remove_privs(file);
if (ret < 0)
goto out;
ret = file_update_time(file);
if (ret < 0)
goto out;
if (iocb->ki_flags & IOCB_NOWAIT) {
/* We could block if there are any pages in the range. */
ret = -EAGAIN;
if (filemap_range_has_page(mapping, pos, end))
if (filemap_invalidate_inode(inode, true, pos, end))
goto out;
} else {
ret = filemap_write_and_wait_range(mapping, pos, end);
if (ret < 0)
goto out;
}
/*
* After a write we want buffered reads to be sure to go to disk to get
* the new data. We invalidate clean cached page from the region we're
* about to write. We do this *before* the write so that we can return
* without clobbering -EIOCBQUEUED from ->direct_IO().
*/
ret = filemap_invalidate_inode(inode, true, pos, end);
if (ret < 0)
goto out;
end = iocb->ki_pos + iov_iter_count(from);
if (end > ictx->zero_point)
ictx->zero_point = end;
fscache_invalidate(netfs_i_cookie(ictx), NULL, i_size_read(inode),
FSCACHE_INVAL_DIO_WRITE);
ret = netfs_unbuffered_write_iter_locked(iocb, from, NULL);
out:
netfs_end_io_direct(inode);
return ret;
}
EXPORT_SYMBOL(netfs_unbuffered_write_iter);
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