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 */
27 int
xfs_break_leased_layouts(struct inode * inode,uint * iolock,bool * did_unlock)28 xfs_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 */
52 int
xfs_fs_get_uuid(struct super_block * sb,u8 * buf,u32 * len,u64 * offset)53 xfs_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 */
76 int
xfs_fs_map_blocks(struct inode * inode,loff_t offset,u64 length,struct iomap * iomap,bool write,u32 * device_generation)77 xfs_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_is_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 goto out_unlock;
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, XFS_PREALLOC_SET);
168 if (!error)
169 error = xfs_log_force_inode(ip);
170 if (error)
171 goto out_unlock;
172
173 } else {
174 xfs_iunlock(ip, lock_flags);
175 }
176 xfs_iunlock(ip, XFS_IOLOCK_EXCL);
177
178 error = xfs_bmbt_to_iomap(ip, iomap, &imap, 0);
179 *device_generation = mp->m_generation;
180 return error;
181 out_unlock:
182 xfs_iunlock(ip, XFS_IOLOCK_EXCL);
183 return error;
184 }
185
186 /*
187 * Ensure the size update falls into a valid allocated block.
188 */
189 static int
xfs_pnfs_validate_isize(struct xfs_inode * ip,xfs_off_t isize)190 xfs_pnfs_validate_isize(
191 struct xfs_inode *ip,
192 xfs_off_t isize)
193 {
194 struct xfs_bmbt_irec imap;
195 int nimaps = 1;
196 int error = 0;
197
198 xfs_ilock(ip, XFS_ILOCK_SHARED);
199 error = xfs_bmapi_read(ip, XFS_B_TO_FSBT(ip->i_mount, isize - 1), 1,
200 &imap, &nimaps, 0);
201 xfs_iunlock(ip, XFS_ILOCK_SHARED);
202 if (error)
203 return error;
204
205 if (imap.br_startblock == HOLESTARTBLOCK ||
206 imap.br_startblock == DELAYSTARTBLOCK ||
207 imap.br_state == XFS_EXT_UNWRITTEN)
208 return -EIO;
209 return 0;
210 }
211
212 /*
213 * Make sure the blocks described by maps are stable on disk. This includes
214 * converting any unwritten extents, flushing the disk cache and updating the
215 * time stamps.
216 *
217 * Note that we rely on the caller to always send us a timestamp update so that
218 * we always commit a transaction here. If that stops being true we will have
219 * to manually flush the cache here similar to what the fsync code path does
220 * for datasyncs on files that have no dirty metadata.
221 */
222 int
xfs_fs_commit_blocks(struct inode * inode,struct iomap * maps,int nr_maps,struct iattr * iattr)223 xfs_fs_commit_blocks(
224 struct inode *inode,
225 struct iomap *maps,
226 int nr_maps,
227 struct iattr *iattr)
228 {
229 struct xfs_inode *ip = XFS_I(inode);
230 struct xfs_mount *mp = ip->i_mount;
231 struct xfs_trans *tp;
232 bool update_isize = false;
233 int error, i;
234 loff_t size;
235
236 ASSERT(iattr->ia_valid & (ATTR_ATIME|ATTR_CTIME|ATTR_MTIME));
237
238 xfs_ilock(ip, XFS_IOLOCK_EXCL);
239
240 size = i_size_read(inode);
241 if ((iattr->ia_valid & ATTR_SIZE) && iattr->ia_size > size) {
242 update_isize = true;
243 size = iattr->ia_size;
244 }
245
246 for (i = 0; i < nr_maps; i++) {
247 u64 start, length, end;
248
249 start = maps[i].offset;
250 if (start > size)
251 continue;
252
253 end = start + maps[i].length;
254 if (end > size)
255 end = size;
256
257 length = end - start;
258 if (!length)
259 continue;
260
261 /*
262 * Make sure reads through the pagecache see the new data.
263 */
264 error = invalidate_inode_pages2_range(inode->i_mapping,
265 start >> PAGE_SHIFT,
266 (end - 1) >> PAGE_SHIFT);
267 WARN_ON_ONCE(error);
268
269 error = xfs_iomap_write_unwritten(ip, start, length, false);
270 if (error)
271 goto out_drop_iolock;
272 }
273
274 if (update_isize) {
275 error = xfs_pnfs_validate_isize(ip, size);
276 if (error)
277 goto out_drop_iolock;
278 }
279
280 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
281 if (error)
282 goto out_drop_iolock;
283
284 xfs_ilock(ip, XFS_ILOCK_EXCL);
285 xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
286 xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
287
288 ASSERT(!(iattr->ia_valid & (ATTR_UID | ATTR_GID)));
289 setattr_copy(&init_user_ns, inode, iattr);
290 if (update_isize) {
291 i_size_write(inode, iattr->ia_size);
292 ip->i_disk_size = iattr->ia_size;
293 }
294
295 xfs_trans_set_sync(tp);
296 error = xfs_trans_commit(tp);
297
298 out_drop_iolock:
299 xfs_iunlock(ip, XFS_IOLOCK_EXCL);
300 return error;
301 }
302