fs/xfs/xfs_pnfs.c

   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
  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
  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         printk_once(KERN_NOTICE
  62 "XFS (%s): using experimental pNFS feature, use at your own risk!\n",
  63                 mp->m_super->s_id);
  64
  65         if (*len < sizeof(uuid_t))
  66                 return -EINVAL;
  67
  68         memcpy(buf, &mp->m_sb.sb_uuid, sizeof(uuid_t));
  69         *len = sizeof(uuid_t);
  70         *offset = offsetof(struct xfs_dsb, sb_uuid);
  71         return 0;
  72 }
  73
  74 /*
  75  * Get a layout for the pNFS client.
  76  */
  77 int
  78 xfs_fs_map_blocks(
  79         struct inode            *inode,
  80         loff_t                  offset,
  81         u64                     length,
  82         struct iomap            *iomap,
  83         bool                    write,
  84         u32                     *device_generation)
  85 {
  86         struct xfs_inode        *ip = XFS_I(inode);
  87         struct xfs_mount        *mp = ip->i_mount;
  88         struct xfs_bmbt_irec    imap;
  89         xfs_fileoff_t           offset_fsb, end_fsb;
  90         loff_t                  limit;
  91         int                     bmapi_flags = XFS_BMAPI_ENTIRE;
  92         int                     nimaps = 1;
  93         uint                    lock_flags;
  94         int                     error = 0;
  95
  96         if (XFS_FORCED_SHUTDOWN(mp))
  97                 return -EIO;
  98
  99         /*
 100          * We can't export inodes residing on the realtime device.  The realtime
 101          * device doesn't have a UUID to identify it, so the client has no way
 102          * to find it.
 103          */
 104         if (XFS_IS_REALTIME_INODE(ip))
 105                 return -ENXIO;
 106
 107         /*
 108          * The pNFS block layout spec actually supports reflink like
 109          * functionality, but the Linux pNFS server doesn't implement it yet.
 110          */
 111         if (xfs_is_reflink_inode(ip))
 112                 return -ENXIO;
 113
 114         /*
 115          * Lock out any other I/O before we flush and invalidate the pagecache,
 116          * and then hand out a layout to the remote system.  This is very
 117          * similar to direct I/O, except that the synchronization is much more
 118          * complicated.  See the comment near xfs_break_leased_layouts
 119          * for a detailed explanation.
 120          */
 121         xfs_ilock(ip, XFS_IOLOCK_EXCL);
 122
 123         error = -EINVAL;
 124         limit = mp->m_super->s_maxbytes;
 125         if (!write)
 126                 limit = max(limit, round_up(i_size_read(inode),
 127                                      inode->i_sb->s_blocksize));
 128         if (offset > limit)
 129                 goto out_unlock;
 130         if (offset > limit - length)
 131                 length = limit - offset;
 132
 133         error = filemap_write_and_wait(inode->i_mapping);
 134         if (error)
 135                 goto out_unlock;
 136         error = invalidate_inode_pages2(inode->i_mapping);
 137         if (WARN_ON_ONCE(error))
 138                 return error;
 139
 140         end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + length);
 141         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 142
 143         lock_flags = xfs_ilock_data_map_shared(ip);
 144         error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
 145                                 &imap, &nimaps, bmapi_flags);
 146
 147         ASSERT(!nimaps || imap.br_startblock != DELAYSTARTBLOCK);
 148
 149         if (!error && write &&
 150             (!nimaps || imap.br_startblock == HOLESTARTBLOCK)) {
 151                 if (offset + length > XFS_ISIZE(ip))
 152                         end_fsb = xfs_iomap_eof_align_last_fsb(ip, end_fsb);
 153                 else if (nimaps && imap.br_startblock == HOLESTARTBLOCK)
 154                         end_fsb = min(end_fsb, imap.br_startoff +
 155                                                imap.br_blockcount);
 156                 xfs_iunlock(ip, lock_flags);
 157
 158                 error = xfs_iomap_write_direct(ip, offset_fsb,
 159                                 end_fsb - offset_fsb, &imap);
 160                 if (error)
 161                         goto out_unlock;
 162
 163                 /*
 164                  * Ensure the next transaction is committed synchronously so
 165                  * that the blocks allocated and handed out to the client are
 166                  * guaranteed to be present even after a server crash.
 167                  */
 168                 error = xfs_update_prealloc_flags(ip,
 169                                 XFS_PREALLOC_SET | XFS_PREALLOC_SYNC);
 170                 if (error)
 171                         goto out_unlock;
 172         } else {
 173                 xfs_iunlock(ip, lock_flags);
 174         }
 175         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 176
 177         error = xfs_bmbt_to_iomap(ip, iomap, &imap, 0);
 178         *device_generation = mp->m_generation;
 179         return error;
 180 out_unlock:
 181         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 182         return error;
 183 }
 184
 185 /*
 186  * Ensure the size update falls into a valid allocated block.
 187  */
 188 static int
 189 xfs_pnfs_validate_isize(
 190         struct xfs_inode        *ip,
 191         xfs_off_t               isize)
 192 {
 193         struct xfs_bmbt_irec    imap;
 194         int                     nimaps = 1;
 195         int                     error = 0;
 196
 197         xfs_ilock(ip, XFS_ILOCK_SHARED);
 198         error = xfs_bmapi_read(ip, XFS_B_TO_FSBT(ip->i_mount, isize - 1), 1,
 199                                 &imap, &nimaps, 0);
 200         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 201         if (error)
 202                 return error;
 203
 204         if (imap.br_startblock == HOLESTARTBLOCK ||
 205             imap.br_startblock == DELAYSTARTBLOCK ||
 206             imap.br_state == XFS_EXT_UNWRITTEN)
 207                 return -EIO;
 208         return 0;
 209 }
 210
 211 /*
 212  * Make sure the blocks described by maps are stable on disk.  This includes
 213  * converting any unwritten extents, flushing the disk cache and updating the
 214  * time stamps.
 215  *
 216  * Note that we rely on the caller to always send us a timestamp update so that
 217  * we always commit a transaction here.  If that stops being true we will have
 218  * to manually flush the cache here similar to what the fsync code path does
 219  * for datasyncs on files that have no dirty metadata.
 220  */
 221 int
 222 xfs_fs_commit_blocks(
 223         struct inode            *inode,
 224         struct iomap            *maps,
 225         int                     nr_maps,
 226         struct iattr            *iattr)
 227 {
 228         struct xfs_inode        *ip = XFS_I(inode);
 229         struct xfs_mount        *mp = ip->i_mount;
 230         struct xfs_trans        *tp;
 231         bool                    update_isize = false;
 232         int                     error, i;
 233         loff_t                  size;
 234
 235         ASSERT(iattr->ia_valid & (ATTR_ATIME|ATTR_CTIME|ATTR_MTIME));
 236
 237         xfs_ilock(ip, XFS_IOLOCK_EXCL);
 238
 239         size = i_size_read(inode);
 240         if ((iattr->ia_valid & ATTR_SIZE) && iattr->ia_size > size) {
 241                 update_isize = true;
 242                 size = iattr->ia_size;
 243         }
 244
 245         for (i = 0; i < nr_maps; i++) {
 246                 u64 start, length, end;
 247
 248                 start = maps[i].offset;
 249                 if (start > size)
 250                         continue;
 251
 252                 end = start + maps[i].length;
 253                 if (end > size)
 254                         end = size;
 255
 256                 length = end - start;
 257                 if (!length)
 258                         continue;
 259
 260                 /*
 261                  * Make sure reads through the pagecache see the new data.
 262                  */
 263                 error = invalidate_inode_pages2_range(inode->i_mapping,
 264                                         start >> PAGE_SHIFT,
 265                                         (end - 1) >> PAGE_SHIFT);
 266                 WARN_ON_ONCE(error);
 267
 268                 error = xfs_iomap_write_unwritten(ip, start, length, false);
 269                 if (error)
 270                         goto out_drop_iolock;
 271         }
 272
 273         if (update_isize) {
 274                 error = xfs_pnfs_validate_isize(ip, size);
 275                 if (error)
 276                         goto out_drop_iolock;
 277         }
 278
 279         error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
 280         if (error)
 281                 goto out_drop_iolock;
 282
 283         xfs_ilock(ip, XFS_ILOCK_EXCL);
 284         xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 285         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 286
 287         xfs_setattr_time(ip, iattr);
 288         if (update_isize) {
 289                 i_size_write(inode, iattr->ia_size);
 290                 ip->i_d.di_size = iattr->ia_size;
 291         }
 292
 293         xfs_trans_set_sync(tp);
 294         error = xfs_trans_commit(tp);
 295
 296 out_drop_iolock:
 297         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 298         return error;
 299 }