1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (c) 2014 Christoph Hellwig.
  4 */
  5#include <linux/iomap.h>
  6#include "xfs.h"
  7#include "xfs_format.h"
  8#include "xfs_log_format.h"
  9#include "xfs_trans_resv.h"
 10#include "xfs_sb.h"
 11#include "xfs_mount.h"
 12#include "xfs_inode.h"
 13#include "xfs_trans.h"
 14#include "xfs_log.h"
 15#include "xfs_bmap.h"
 16#include "xfs_bmap_util.h"
 17#include "xfs_error.h"
 18#include "xfs_iomap.h"
 19#include "xfs_shared.h"
 20#include "xfs_bit.h"
 21#include "xfs_pnfs.h"
 22
 23/*
 24 * Ensure that we do not have any outstanding pNFS layouts that can be used by
 25 * clients to directly read from or write to this inode.  This must be called
 26 * before every operation that can remove blocks from the extent map.
 27 * Additionally we call it during the write operation, where aren't concerned
 28 * about exposing unallocated blocks but just want to provide basic
 29 * synchronization between a local writer and pNFS clients.  mmap writes would
 30 * also benefit from this sort of synchronization, but due to the tricky locking
 31 * rules in the page fault path we don't bother.
 32 */
 33int
 34xfs_break_layouts(
 35	struct inode		*inode,
 36	uint			*iolock)
 37{
 38	struct xfs_inode	*ip = XFS_I(inode);
 39	int			error;
 40
 41	ASSERT(xfs_isilocked(ip, XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL));
 42
 43	while ((error = break_layout(inode, false) == -EWOULDBLOCK)) {
 44		xfs_iunlock(ip, *iolock);
 45		error = break_layout(inode, true);
 46		*iolock = XFS_IOLOCK_EXCL;
 47		xfs_ilock(ip, *iolock);
 48	}
 49
 50	return error;
 51}
 52
 53/*
 54 * Get a unique ID including its location so that the client can identify
 55 * the exported device.
 56 */
 57int
 58xfs_fs_get_uuid(
 59	struct super_block	*sb,
 60	u8			*buf,
 61	u32			*len,
 62	u64			*offset)
 63{
 64	struct xfs_mount	*mp = XFS_M(sb);
 65
 66	printk_once(KERN_NOTICE
 67"XFS (%s): using experimental pNFS feature, use at your own risk!\n",
 68		mp->m_fsname);
 69
 70	if (*len < sizeof(uuid_t))
 71		return -EINVAL;
 72
 73	memcpy(buf, &mp->m_sb.sb_uuid, sizeof(uuid_t));
 74	*len = sizeof(uuid_t);
 75	*offset = offsetof(struct xfs_dsb, sb_uuid);
 76	return 0;
 77}
 78
 79/*
 80 * Get a layout for the pNFS client.
 81 */
 82int
 83xfs_fs_map_blocks(
 84	struct inode		*inode,
 85	loff_t			offset,
 86	u64			length,
 87	struct iomap		*iomap,
 88	bool			write,
 89	u32			*device_generation)
 90{
 91	struct xfs_inode	*ip = XFS_I(inode);
 92	struct xfs_mount	*mp = ip->i_mount;
 93	struct xfs_bmbt_irec	imap;
 94	xfs_fileoff_t		offset_fsb, end_fsb;
 95	loff_t			limit;
 96	int			bmapi_flags = XFS_BMAPI_ENTIRE;
 97	int			nimaps = 1;
 98	uint			lock_flags;
 99	int			error = 0;
100
101	if (XFS_FORCED_SHUTDOWN(mp))
102		return -EIO;
103
104	/*
105	 * We can't export inodes residing on the realtime device.  The realtime
106	 * device doesn't have a UUID to identify it, so the client has no way
107	 * to find it.
108	 */
109	if (XFS_IS_REALTIME_INODE(ip))
110		return -ENXIO;
111
112	/*
113	 * The pNFS block layout spec actually supports reflink like
114	 * functionality, but the Linux pNFS server doesn't implement it yet.
115	 */
116	if (xfs_is_reflink_inode(ip))
117		return -ENXIO;
118
119	/*
120	 * Lock out any other I/O before we flush and invalidate the pagecache,
121	 * and then hand out a layout to the remote system.  This is very
122	 * similar to direct I/O, except that the synchronization is much more
123	 * complicated.  See the comment near xfs_break_layouts for a detailed
124	 * explanation.
125	 */
126	xfs_ilock(ip, XFS_IOLOCK_EXCL);
127
128	error = -EINVAL;
129	limit = mp->m_super->s_maxbytes;
130	if (!write)
131		limit = max(limit, round_up(i_size_read(inode),
132				     inode->i_sb->s_blocksize));
133	if (offset > limit)
134		goto out_unlock;
135	if (offset > limit - length)
136		length = limit - offset;
137
138	error = filemap_write_and_wait(inode->i_mapping);
139	if (error)
140		goto out_unlock;
141	error = invalidate_inode_pages2(inode->i_mapping);
142	if (WARN_ON_ONCE(error))
143		return error;
144
145	end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + length);
146	offset_fsb = XFS_B_TO_FSBT(mp, offset);
147
148	lock_flags = xfs_ilock_data_map_shared(ip);
149	error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
150				&imap, &nimaps, bmapi_flags);
151	xfs_iunlock(ip, lock_flags);
152
153	if (error)
154		goto out_unlock;
155
156	if (write) {
157		enum xfs_prealloc_flags	flags = 0;
158
159		ASSERT(imap.br_startblock != DELAYSTARTBLOCK);
160
161		if (!nimaps || imap.br_startblock == HOLESTARTBLOCK) {
162			/*
163			 * xfs_iomap_write_direct() expects to take ownership of
164			 * the shared ilock.
165			 */
166			xfs_ilock(ip, XFS_ILOCK_SHARED);
167			error = xfs_iomap_write_direct(ip, offset, length,
168						       &imap, nimaps);
169			if (error)
170				goto out_unlock;
171
172			/*
173			 * Ensure the next transaction is committed
174			 * synchronously so that the blocks allocated and
175			 * handed out to the client are guaranteed to be
176			 * present even after a server crash.
177			 */
178			flags |= XFS_PREALLOC_SET | XFS_PREALLOC_SYNC;
179		}
180
181		error = xfs_update_prealloc_flags(ip, flags);
182		if (error)
183			goto out_unlock;
184	}
185	xfs_iunlock(ip, XFS_IOLOCK_EXCL);
186
187	xfs_bmbt_to_iomap(ip, iomap, &imap);
188	*device_generation = mp->m_generation;
189	return error;
190out_unlock:
191	xfs_iunlock(ip, XFS_IOLOCK_EXCL);
192	return error;
193}
194
195/*
196 * Ensure the size update falls into a valid allocated block.
197 */
198static int
199xfs_pnfs_validate_isize(
200	struct xfs_inode	*ip,
201	xfs_off_t		isize)
202{
203	struct xfs_bmbt_irec	imap;
204	int			nimaps = 1;
205	int			error = 0;
206
207	xfs_ilock(ip, XFS_ILOCK_SHARED);
208	error = xfs_bmapi_read(ip, XFS_B_TO_FSBT(ip->i_mount, isize - 1), 1,
209				&imap, &nimaps, 0);
210	xfs_iunlock(ip, XFS_ILOCK_SHARED);
211	if (error)
212		return error;
213
214	if (imap.br_startblock == HOLESTARTBLOCK ||
215	    imap.br_startblock == DELAYSTARTBLOCK ||
216	    imap.br_state == XFS_EXT_UNWRITTEN)
217		return -EIO;
218	return 0;
219}
220
221/*
222 * Make sure the blocks described by maps are stable on disk.  This includes
223 * converting any unwritten extents, flushing the disk cache and updating the
224 * time stamps.
225 *
226 * Note that we rely on the caller to always send us a timestamp update so that
227 * we always commit a transaction here.  If that stops being true we will have
228 * to manually flush the cache here similar to what the fsync code path does
229 * for datasyncs on files that have no dirty metadata.
230 */
231int
232xfs_fs_commit_blocks(
233	struct inode		*inode,
234	struct iomap		*maps,
235	int			nr_maps,
236	struct iattr		*iattr)
237{
238	struct xfs_inode	*ip = XFS_I(inode);
239	struct xfs_mount	*mp = ip->i_mount;
240	struct xfs_trans	*tp;
241	bool			update_isize = false;
242	int			error, i;
243	loff_t			size;
244
245	ASSERT(iattr->ia_valid & (ATTR_ATIME|ATTR_CTIME|ATTR_MTIME));
246
247	xfs_ilock(ip, XFS_IOLOCK_EXCL);
248
249	size = i_size_read(inode);
250	if ((iattr->ia_valid & ATTR_SIZE) && iattr->ia_size > size) {
251		update_isize = true;
252		size = iattr->ia_size;
253	}
254
255	for (i = 0; i < nr_maps; i++) {
256		u64 start, length, end;
257
258		start = maps[i].offset;
259		if (start > size)
260			continue;
261
262		end = start + maps[i].length;
263		if (end > size)
264			end = size;
265
266		length = end - start;
267		if (!length)
268			continue;
269	
270		/*
271		 * Make sure reads through the pagecache see the new data.
272		 */
273		error = invalidate_inode_pages2_range(inode->i_mapping,
274					start >> PAGE_SHIFT,
275					(end - 1) >> PAGE_SHIFT);
276		WARN_ON_ONCE(error);
277
278		error = xfs_iomap_write_unwritten(ip, start, length, false);
279		if (error)
280			goto out_drop_iolock;
281	}
282
283	if (update_isize) {
284		error = xfs_pnfs_validate_isize(ip, size);
285		if (error)
286			goto out_drop_iolock;
287	}
288
289	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
290	if (error)
291		goto out_drop_iolock;
292
293	xfs_ilock(ip, XFS_ILOCK_EXCL);
294	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
295	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
296
297	xfs_setattr_time(ip, iattr);
298	if (update_isize) {
299		i_size_write(inode, iattr->ia_size);
300		ip->i_d.di_size = iattr->ia_size;
301	}
302
303	xfs_trans_set_sync(tp);
304	error = xfs_trans_commit(tp);
305
306out_drop_iolock:
307	xfs_iunlock(ip, XFS_IOLOCK_EXCL);
308	return error;
309}