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