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Linux/fs/xfs/xfs_pnfs.c

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  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  */
 26 int
 27 xfs_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  */
 51 int
 52 xfs_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  */
 76 int
 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_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;
184 out_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  */
192 static int
193 xfs_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  */
225 int
226 xfs_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 
300 out_drop_iolock:
301         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
302         return error;
303 }
304 

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