1/*
2 * Copyright (c) 2014 Christoph Hellwig.
3 */
4#include "xfs.h"
5#include "xfs_format.h"
6#include "xfs_log_format.h"
7#include "xfs_trans_resv.h"
8#include "xfs_sb.h"
9#include "xfs_mount.h"
10#include "xfs_inode.h"
11#include "xfs_trans.h"
12#include "xfs_log.h"
13#include "xfs_bmap.h"
14#include "xfs_bmap_util.h"
15#include "xfs_error.h"
16#include "xfs_iomap.h"
17#include "xfs_shared.h"
18#include "xfs_bit.h"
19#include "xfs_pnfs.h"
20
21/*
22 * Ensure that we do not have any outstanding pNFS layouts that can be used by
23 * clients to directly read from or write to this inode.  This must be called
24 * before every operation that can remove blocks from the extent map.
25 * Additionally we call it during the write operation, where aren't concerned
26 * about exposing unallocated blocks but just want to provide basic
27 * synchronization between a local writer and pNFS clients.  mmap writes would
28 * also benefit from this sort of synchronization, but due to the tricky locking
29 * rules in the page fault path we don't bother.
30 */
31int
32xfs_break_layouts(
33	struct inode		*inode,
34	uint			*iolock,
35	bool			with_imutex)
36{
37	struct xfs_inode	*ip = XFS_I(inode);
38	int			error;
39
40	ASSERT(xfs_isilocked(ip, XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL));
41
42	while ((error = break_layout(inode, false) == -EWOULDBLOCK)) {
43		xfs_iunlock(ip, *iolock);
44		if (with_imutex && (*iolock & XFS_IOLOCK_EXCL))
45			mutex_unlock(&inode->i_mutex);
46		error = break_layout(inode, true);
47		*iolock = XFS_IOLOCK_EXCL;
48		if (with_imutex)
49			mutex_lock(&inode->i_mutex);
50		xfs_ilock(ip, *iolock);
51	}
52
53	return error;
54}
55
56/*
57 * Get a unique ID including its location so that the client can identify
58 * the exported device.
59 */
60int
61xfs_fs_get_uuid(
62	struct super_block	*sb,
63	u8			*buf,
64	u32			*len,
65	u64			*offset)
66{
67	struct xfs_mount	*mp = XFS_M(sb);
68
69	printk_once(KERN_NOTICE
70"XFS (%s): using experimental pNFS feature, use at your own risk!\n",
71		mp->m_fsname);
72
73	if (*len < sizeof(uuid_t))
74		return -EINVAL;
75
76	memcpy(buf, &mp->m_sb.sb_uuid, sizeof(uuid_t));
77	*len = sizeof(uuid_t);
78	*offset = offsetof(struct xfs_dsb, sb_uuid);
79	return 0;
80}
81
82static void
83xfs_bmbt_to_iomap(
84	struct xfs_inode	*ip,
85	struct iomap		*iomap,
86	struct xfs_bmbt_irec	*imap)
87{
88	struct xfs_mount	*mp = ip->i_mount;
89
90	if (imap->br_startblock == HOLESTARTBLOCK) {
91		iomap->blkno = IOMAP_NULL_BLOCK;
92		iomap->type = IOMAP_HOLE;
93	} else if (imap->br_startblock == DELAYSTARTBLOCK) {
94		iomap->blkno = IOMAP_NULL_BLOCK;
95		iomap->type = IOMAP_DELALLOC;
96	} else {
97		iomap->blkno =
98			XFS_FSB_TO_DADDR(ip->i_mount, imap->br_startblock);
99		if (imap->br_state == XFS_EXT_UNWRITTEN)
100			iomap->type = IOMAP_UNWRITTEN;
101		else
102			iomap->type = IOMAP_MAPPED;
103	}
104	iomap->offset = XFS_FSB_TO_B(mp, imap->br_startoff);
105	iomap->length = XFS_FSB_TO_B(mp, imap->br_blockcount);
106}
107
108/*
109 * Get a layout for the pNFS client.
110 */
111int
112xfs_fs_map_blocks(
113	struct inode		*inode,
114	loff_t			offset,
115	u64			length,
116	struct iomap		*iomap,
117	bool			write,
118	u32			*device_generation)
119{
120	struct xfs_inode	*ip = XFS_I(inode);
121	struct xfs_mount	*mp = ip->i_mount;
122	struct xfs_bmbt_irec	imap;
123	xfs_fileoff_t		offset_fsb, end_fsb;
124	loff_t			limit;
125	int			bmapi_flags = XFS_BMAPI_ENTIRE;
126	int			nimaps = 1;
127	uint			lock_flags;
128	int			error = 0;
129
130	if (XFS_FORCED_SHUTDOWN(mp))
131		return -EIO;
132
133	/*
134	 * We can't export inodes residing on the realtime device.  The realtime
135	 * device doesn't have a UUID to identify it, so the client has no way
136	 * to find it.
137	 */
138	if (XFS_IS_REALTIME_INODE(ip))
139		return -ENXIO;
140
141	/*
142	 * Lock out any other I/O before we flush and invalidate the pagecache,
143	 * and then hand out a layout to the remote system.  This is very
144	 * similar to direct I/O, except that the synchronization is much more
145	 * complicated.  See the comment near xfs_break_layouts for a detailed
146	 * explanation.
147	 */
148	xfs_ilock(ip, XFS_IOLOCK_EXCL);
149
150	error = -EINVAL;
151	limit = mp->m_super->s_maxbytes;
152	if (!write)
153		limit = max(limit, round_up(i_size_read(inode),
154				     inode->i_sb->s_blocksize));
155	if (offset > limit)
156		goto out_unlock;
157	if (offset > limit - length)
158		length = limit - offset;
159
160	error = filemap_write_and_wait(inode->i_mapping);
161	if (error)
162		goto out_unlock;
163	error = invalidate_inode_pages2(inode->i_mapping);
164	if (WARN_ON_ONCE(error))
165		return error;
166
167	end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + length);
168	offset_fsb = XFS_B_TO_FSBT(mp, offset);
169
170	lock_flags = xfs_ilock_data_map_shared(ip);
171	error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
172				&imap, &nimaps, bmapi_flags);
173	xfs_iunlock(ip, lock_flags);
174
175	if (error)
176		goto out_unlock;
177
178	if (write) {
179		enum xfs_prealloc_flags	flags = 0;
180
181		ASSERT(imap.br_startblock != DELAYSTARTBLOCK);
182
183		if (!nimaps || imap.br_startblock == HOLESTARTBLOCK) {
184			error = xfs_iomap_write_direct(ip, offset, length,
185						       &imap, nimaps);
186			if (error)
187				goto out_unlock;
188
189			/*
190			 * Ensure the next transaction is committed
191			 * synchronously so that the blocks allocated and
192			 * handed out to the client are guaranteed to be
193			 * present even after a server crash.
194			 */
195			flags |= XFS_PREALLOC_SET | XFS_PREALLOC_SYNC;
196		}
197
198		error = xfs_update_prealloc_flags(ip, flags);
199		if (error)
200			goto out_unlock;
201	}
202	xfs_iunlock(ip, XFS_IOLOCK_EXCL);
203
204	xfs_bmbt_to_iomap(ip, iomap, &imap);
205	*device_generation = mp->m_generation;
206	return error;
207out_unlock:
208	xfs_iunlock(ip, XFS_IOLOCK_EXCL);
209	return error;
210}
211
212/*
213 * Ensure the size update falls into a valid allocated block.
214 */
215static int
216xfs_pnfs_validate_isize(
217	struct xfs_inode	*ip,
218	xfs_off_t		isize)
219{
220	struct xfs_bmbt_irec	imap;
221	int			nimaps = 1;
222	int			error = 0;
223
224	xfs_ilock(ip, XFS_ILOCK_SHARED);
225	error = xfs_bmapi_read(ip, XFS_B_TO_FSBT(ip->i_mount, isize - 1), 1,
226				&imap, &nimaps, 0);
227	xfs_iunlock(ip, XFS_ILOCK_SHARED);
228	if (error)
229		return error;
230
231	if (imap.br_startblock == HOLESTARTBLOCK ||
232	    imap.br_startblock == DELAYSTARTBLOCK ||
233	    imap.br_state == XFS_EXT_UNWRITTEN)
234		return -EIO;
235	return 0;
236}
237
238/*
239 * Make sure the blocks described by maps are stable on disk.  This includes
240 * converting any unwritten extents, flushing the disk cache and updating the
241 * time stamps.
242 *
243 * Note that we rely on the caller to always send us a timestamp update so that
244 * we always commit a transaction here.  If that stops being true we will have
245 * to manually flush the cache here similar to what the fsync code path does
246 * for datasyncs on files that have no dirty metadata.
247 */
248int
249xfs_fs_commit_blocks(
250	struct inode		*inode,
251	struct iomap		*maps,
252	int			nr_maps,
253	struct iattr		*iattr)
254{
255	struct xfs_inode	*ip = XFS_I(inode);
256	struct xfs_mount	*mp = ip->i_mount;
257	struct xfs_trans	*tp;
258	bool			update_isize = false;
259	int			error, i;
260	loff_t			size;
261
262	ASSERT(iattr->ia_valid & (ATTR_ATIME|ATTR_CTIME|ATTR_MTIME));
263
264	xfs_ilock(ip, XFS_IOLOCK_EXCL);
265
266	size = i_size_read(inode);
267	if ((iattr->ia_valid & ATTR_SIZE) && iattr->ia_size > size) {
268		update_isize = true;
269		size = iattr->ia_size;
270	}
271
272	for (i = 0; i < nr_maps; i++) {
273		u64 start, length, end;
274
275		start = maps[i].offset;
276		if (start > size)
277			continue;
278
279		end = start + maps[i].length;
280		if (end > size)
281			end = size;
282
283		length = end - start;
284		if (!length)
285			continue;
286
287		/*
288		 * Make sure reads through the pagecache see the new data.
289		 */
290		error = invalidate_inode_pages2_range(inode->i_mapping,
291					start >> PAGE_CACHE_SHIFT,
292					(end - 1) >> PAGE_CACHE_SHIFT);
293		WARN_ON_ONCE(error);
294
295		error = xfs_iomap_write_unwritten(ip, start, length);
296		if (error)
297			goto out_drop_iolock;
298	}
299
300	if (update_isize) {
301		error = xfs_pnfs_validate_isize(ip, size);
302		if (error)
303			goto out_drop_iolock;
304	}
305
306	tp = xfs_trans_alloc(mp, XFS_TRANS_SETATTR_NOT_SIZE);
307	error = xfs_trans_reserve(tp, &M_RES(mp)->tr_ichange, 0, 0);
308	if (error) {
309		xfs_trans_cancel(tp, 0);
310		goto out_drop_iolock;
311	}
312
313	xfs_ilock(ip, XFS_ILOCK_EXCL);
314	xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
315	xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
316
317	xfs_setattr_time(ip, iattr);
318	if (update_isize) {
319		i_size_write(inode, iattr->ia_size);
320		ip->i_d.di_size = iattr->ia_size;
321	}
322
323	xfs_trans_set_sync(tp);
324	error = xfs_trans_commit(tp, 0);
325
326out_drop_iolock:
327	xfs_iunlock(ip, XFS_IOLOCK_EXCL);
328	return error;
329}
330