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#include "xfs_pnfs.h"
 16
 17/*
 18 * Ensure that we do not have any outstanding pNFS layouts that can be used by
 19 * clients to directly read from or write to this inode.  This must be called
 20 * before every operation that can remove blocks from the extent map.
 21 * Additionally we call it during the write operation, where aren't concerned
 22 * about exposing unallocated blocks but just want to provide basic
 23 * synchronization between a local writer and pNFS clients.  mmap writes would
 24 * also benefit from this sort of synchronization, but due to the tricky locking
 25 * rules in the page fault path we don't bother.
 26 */
 27int
 28xfs_break_leased_layouts(
 29	struct inode		*inode,
 30	uint			*iolock,
 31	bool			*did_unlock)
 32{
 33	struct xfs_inode	*ip = XFS_I(inode);
 34	int			error;
 35
 36	while ((error = break_layout(inode, false)) == -EWOULDBLOCK) {
 37		xfs_iunlock(ip, *iolock);
 38		*did_unlock = true;
 39		error = break_layout(inode, true);
 40		*iolock &= ~XFS_IOLOCK_SHARED;
 41		*iolock |= XFS_IOLOCK_EXCL;
 42		xfs_ilock(ip, *iolock);
 43	}
 44
 45	return error;
 46}
 47
 48/*
 49 * Get a unique ID including its location so that the client can identify
 50 * the exported device.
 51 */
 52int
 53xfs_fs_get_uuid(
 54	struct super_block	*sb,
 55	u8			*buf,
 56	u32			*len,
 57	u64			*offset)
 58{
 59	struct xfs_mount	*mp = XFS_M(sb);
 60
 61	xfs_notice_once(mp,
 62"Using experimental pNFS feature, use at your own risk!");
 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
146	ASSERT(!nimaps || imap.br_startblock != DELAYSTARTBLOCK);
147
148	if (!error && write &&
149	    (!nimaps || imap.br_startblock == HOLESTARTBLOCK)) {
150		if (offset + length > XFS_ISIZE(ip))
151			end_fsb = xfs_iomap_eof_align_last_fsb(ip, end_fsb);
152		else if (nimaps && imap.br_startblock == HOLESTARTBLOCK)
153			end_fsb = min(end_fsb, imap.br_startoff +
154					       imap.br_blockcount);
155		xfs_iunlock(ip, lock_flags);
156
157		error = xfs_iomap_write_direct(ip, offset_fsb,
158				end_fsb - offset_fsb, &imap);
159		if (error)
160			goto out_unlock;
161
162		/*
163		 * Ensure the next transaction is committed synchronously so
164		 * that the blocks allocated and handed out to the client are
165		 * guaranteed to be present even after a server crash.
166		 */
167		error = xfs_update_prealloc_flags(ip,
168				XFS_PREALLOC_SET | XFS_PREALLOC_SYNC);
169		if (error)
170			goto out_unlock;
171	} else {
172		xfs_iunlock(ip, lock_flags);
173	}
174	xfs_iunlock(ip, XFS_IOLOCK_EXCL);
175
176	error = xfs_bmbt_to_iomap(ip, iomap, &imap, 0);
177	*device_generation = mp->m_generation;
178	return error;
179out_unlock:
180	xfs_iunlock(ip, XFS_IOLOCK_EXCL);
181	return error;
182}
183
184/*
185 * Ensure the size update falls into a valid allocated block.
186 */
187static int
188xfs_pnfs_validate_isize(
189	struct xfs_inode	*ip,
190	xfs_off_t		isize)
191{
192	struct xfs_bmbt_irec	imap;
193	int			nimaps = 1;
194	int			error = 0;
195
196	xfs_ilock(ip, XFS_ILOCK_SHARED);
197	error = xfs_bmapi_read(ip, XFS_B_TO_FSBT(ip->i_mount, isize - 1), 1,
198				&imap, &nimaps, 0);
199	xfs_iunlock(ip, XFS_ILOCK_SHARED);
200	if (error)
201		return error;
202
203	if (imap.br_startblock == HOLESTARTBLOCK ||
204	    imap.br_startblock == DELAYSTARTBLOCK ||
205	    imap.br_state == XFS_EXT_UNWRITTEN)
206		return -EIO;
207	return 0;
208}
209
210/*
211 * Make sure the blocks described by maps are stable on disk.  This includes
212 * converting any unwritten extents, flushing the disk cache and updating the
213 * time stamps.
214 *
215 * Note that we rely on the caller to always send us a timestamp update so that
216 * we always commit a transaction here.  If that stops being true we will have
217 * to manually flush the cache here similar to what the fsync code path does
218 * for datasyncs on files that have no dirty metadata.
219 */
220int
221xfs_fs_commit_blocks(
222	struct inode		*inode,
223	struct iomap		*maps,
224	int			nr_maps,
225	struct iattr		*iattr)
226{
227	struct xfs_inode	*ip = XFS_I(inode);
228	struct xfs_mount	*mp = ip->i_mount;
229	struct xfs_trans	*tp;
230	bool			update_isize = false;
231	int			error, i;
232	loff_t			size;
233
234	ASSERT(iattr->ia_valid & (ATTR_ATIME|ATTR_CTIME|ATTR_MTIME));
235
236	xfs_ilock(ip, XFS_IOLOCK_EXCL);
237
238	size = i_size_read(inode);
239	if ((iattr->ia_valid & ATTR_SIZE) && iattr->ia_size > size) {
240		update_isize = true;
241		size = iattr->ia_size;
242	}
243
244	for (i = 0; i < nr_maps; i++) {
245		u64 start, length, end;
246
247		start = maps[i].offset;
248		if (start > size)
249			continue;
250
251		end = start + maps[i].length;
252		if (end > size)
253			end = size;
254
255		length = end - start;
256		if (!length)
257			continue;
258	
259		/*
260		 * Make sure reads through the pagecache see the new data.
261		 */
262		error = invalidate_inode_pages2_range(inode->i_mapping,
263					start >> PAGE_SHIFT,
264					(end - 1) >> PAGE_SHIFT);
265		WARN_ON_ONCE(error);
266
267		error = xfs_iomap_write_unwritten(ip, start, length, false);
268		if (error)
269			goto out_drop_iolock;
270	}
271
272	if (update_isize) {
273		error = xfs_pnfs_validate_isize(ip, size);
274		if (error)
275			goto out_drop_iolock;
276	}
277
278	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
279	if (error)
280		goto out_drop_iolock;
281
282	xfs_ilock(ip, XFS_ILOCK_EXCL);
283	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
284	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
285
286	xfs_setattr_time(ip, iattr);
287	if (update_isize) {
288		i_size_write(inode, iattr->ia_size);
289		ip->i_d.di_size = iattr->ia_size;
290	}
291
292	xfs_trans_set_sync(tp);
293	error = xfs_trans_commit(tp);
294
295out_drop_iolock:
296	xfs_iunlock(ip, XFS_IOLOCK_EXCL);
297	return error;
298}