fs/xfs/xfs_pnfs.c

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