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Linux/fs/xfs/xfs_pnfs.c

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  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  */
 31 int
 32 xfs_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  */
 60 int
 61 xfs_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 
 82 static void
 83 xfs_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  */
111 int
112 xfs_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;
207 out_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  */
215 static int
216 xfs_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  */
248 int
249 xfs_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);
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);
325 
326 out_drop_iolock:
327         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
328         return error;
329 }
330 

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