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

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