1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* Unbuffered and direct write support. 3 * 4 * Copyright (C) 2023 Red Hat, Inc. All Rights Reserved. 5 * Written by David Howells (dhowells@redhat.com) 6 */ 7 8 #include <linux/export.h> 9 #include <linux/uio.h> 10 #include "internal.h" 11 12 static void netfs_cleanup_dio_write(struct netfs_io_request *wreq) 13 { 14 struct inode *inode = wreq->inode; 15 unsigned long long end = wreq->start + wreq->len; 16 17 if (!wreq->error && 18 i_size_read(inode) < end) { 19 if (wreq->netfs_ops->update_i_size) 20 wreq->netfs_ops->update_i_size(inode, end); 21 else 22 i_size_write(inode, end); 23 } 24 } 25 26 /* 27 * Perform an unbuffered write where we may have to do an RMW operation on an 28 * encrypted file. This can also be used for direct I/O writes. 29 */ 30 static ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *iter, 31 struct netfs_group *netfs_group) 32 { 33 struct netfs_io_request *wreq; 34 unsigned long long start = iocb->ki_pos; 35 unsigned long long end = start + iov_iter_count(iter); 36 ssize_t ret, n; 37 bool async = !is_sync_kiocb(iocb); 38 39 _enter(""); 40 41 /* We're going to need a bounce buffer if what we transmit is going to 42 * be different in some way to the source buffer, e.g. because it gets 43 * encrypted/compressed or because it needs expanding to a block size. 44 */ 45 // TODO 46 47 _debug("uw %llx-%llx", start, end); 48 49 wreq = netfs_alloc_request(iocb->ki_filp->f_mapping, iocb->ki_filp, 50 start, end - start, 51 iocb->ki_flags & IOCB_DIRECT ? 52 NETFS_DIO_WRITE : NETFS_UNBUFFERED_WRITE); 53 if (IS_ERR(wreq)) 54 return PTR_ERR(wreq); 55 56 { 57 /* If this is an async op and we're not using a bounce buffer, 58 * we have to save the source buffer as the iterator is only 59 * good until we return. In such a case, extract an iterator 60 * to represent as much of the the output buffer as we can 61 * manage. Note that the extraction might not be able to 62 * allocate a sufficiently large bvec array and may shorten the 63 * request. 64 */ 65 if (async || user_backed_iter(iter)) { 66 n = netfs_extract_user_iter(iter, wreq->len, &wreq->iter, 0); 67 if (n < 0) { 68 ret = n; 69 goto out; 70 } 71 wreq->direct_bv = (struct bio_vec *)wreq->iter.bvec; 72 wreq->direct_bv_count = n; 73 wreq->direct_bv_unpin = iov_iter_extract_will_pin(iter); 74 wreq->len = iov_iter_count(&wreq->iter); 75 } else { 76 wreq->iter = *iter; 77 } 78 79 wreq->io_iter = wreq->iter; 80 } 81 82 /* Copy the data into the bounce buffer and encrypt it. */ 83 // TODO 84 85 /* Dispatch the write. */ 86 __set_bit(NETFS_RREQ_UPLOAD_TO_SERVER, &wreq->flags); 87 if (async) 88 wreq->iocb = iocb; 89 wreq->cleanup = netfs_cleanup_dio_write; 90 ret = netfs_begin_write(wreq, is_sync_kiocb(iocb), 91 iocb->ki_flags & IOCB_DIRECT ? 92 netfs_write_trace_dio_write : 93 netfs_write_trace_unbuffered_write); 94 if (ret < 0) { 95 _debug("begin = %zd", ret); 96 goto out; 97 } 98 99 if (!async) { 100 trace_netfs_rreq(wreq, netfs_rreq_trace_wait_ip); 101 wait_on_bit(&wreq->flags, NETFS_RREQ_IN_PROGRESS, 102 TASK_UNINTERRUPTIBLE); 103 104 ret = wreq->error; 105 _debug("waited = %zd", ret); 106 if (ret == 0) { 107 ret = wreq->transferred; 108 iocb->ki_pos += ret; 109 } 110 } else { 111 ret = -EIOCBQUEUED; 112 } 113 114 out: 115 netfs_put_request(wreq, false, netfs_rreq_trace_put_return); 116 return ret; 117 } 118 119 /** 120 * netfs_unbuffered_write_iter - Unbuffered write to a file 121 * @iocb: IO state structure 122 * @from: iov_iter with data to write 123 * 124 * Do an unbuffered write to a file, writing the data directly to the server 125 * and not lodging the data in the pagecache. 126 * 127 * Return: 128 * * Negative error code if no data has been written at all of 129 * vfs_fsync_range() failed for a synchronous write 130 * * Number of bytes written, even for truncated writes 131 */ 132 ssize_t netfs_unbuffered_write_iter(struct kiocb *iocb, struct iov_iter *from) 133 { 134 struct file *file = iocb->ki_filp; 135 struct inode *inode = file->f_mapping->host; 136 struct netfs_inode *ictx = netfs_inode(inode); 137 unsigned long long end; 138 ssize_t ret; 139 140 _enter("%llx,%zx,%llx", iocb->ki_pos, iov_iter_count(from), i_size_read(inode)); 141 142 trace_netfs_write_iter(iocb, from); 143 netfs_stat(&netfs_n_rh_dio_write); 144 145 ret = netfs_start_io_direct(inode); 146 if (ret < 0) 147 return ret; 148 ret = generic_write_checks(iocb, from); 149 if (ret < 0) 150 goto out; 151 ret = file_remove_privs(file); 152 if (ret < 0) 153 goto out; 154 ret = file_update_time(file); 155 if (ret < 0) 156 goto out; 157 ret = kiocb_invalidate_pages(iocb, iov_iter_count(from)); 158 if (ret < 0) 159 goto out; 160 end = iocb->ki_pos + iov_iter_count(from); 161 if (end > ictx->zero_point) 162 ictx->zero_point = end; 163 164 fscache_invalidate(netfs_i_cookie(ictx), NULL, i_size_read(inode), 165 FSCACHE_INVAL_DIO_WRITE); 166 ret = netfs_unbuffered_write_iter_locked(iocb, from, NULL); 167 out: 168 netfs_end_io_direct(inode); 169 return ret; 170 } 171 EXPORT_SYMBOL(netfs_unbuffered_write_iter); 172