fs/xfs/xfs_pnfs.c

   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                         /*
 185                          * xfs_iomap_write_direct() expects to take ownership of
 186                          * the shared ilock.
 187                          */
 188                         xfs_ilock(ip, XFS_ILOCK_SHARED);
 189                         error = xfs_iomap_write_direct(ip, offset, length,
 190                                                        &imap, nimaps);
 191                         if (error)
 192                                 goto out_unlock;
 193
 194                         /*
 195                          * Ensure the next transaction is committed
 196                          * synchronously so that the blocks allocated and
 197                          * handed out to the client are guaranteed to be
 198                          * present even after a server crash.
 199                          */
 200                         flags |= XFS_PREALLOC_SET | XFS_PREALLOC_SYNC;
 201                 }
 202
 203                 error = xfs_update_prealloc_flags(ip, flags);
 204                 if (error)
 205                         goto out_unlock;
 206         }
 207         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 208
 209         xfs_bmbt_to_iomap(ip, iomap, &imap);
 210         *device_generation = mp->m_generation;
 211         return error;
 212 out_unlock:
 213         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 214         return error;
 215 }
 216
 217 /*
 218  * Ensure the size update falls into a valid allocated block.
 219  */
 220 static int
 221 xfs_pnfs_validate_isize(
 222         struct xfs_inode        *ip,
 223         xfs_off_t               isize)
 224 {
 225         struct xfs_bmbt_irec    imap;
 226         int                     nimaps = 1;
 227         int                     error = 0;
 228
 229         xfs_ilock(ip, XFS_ILOCK_SHARED);
 230         error = xfs_bmapi_read(ip, XFS_B_TO_FSBT(ip->i_mount, isize - 1), 1,
 231                                 &imap, &nimaps, 0);
 232         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 233         if (error)
 234                 return error;
 235
 236         if (imap.br_startblock == HOLESTARTBLOCK ||
 237             imap.br_startblock == DELAYSTARTBLOCK ||
 238             imap.br_state == XFS_EXT_UNWRITTEN)
 239                 return -EIO;
 240         return 0;
 241 }
 242
 243 /*
 244  * Make sure the blocks described by maps are stable on disk.  This includes
 245  * converting any unwritten extents, flushing the disk cache and updating the
 246  * time stamps.
 247  *
 248  * Note that we rely on the caller to always send us a timestamp update so that
 249  * we always commit a transaction here.  If that stops being true we will have
 250  * to manually flush the cache here similar to what the fsync code path does
 251  * for datasyncs on files that have no dirty metadata.
 252  */
 253 int
 254 xfs_fs_commit_blocks(
 255         struct inode            *inode,
 256         struct iomap            *maps,
 257         int                     nr_maps,
 258         struct iattr            *iattr)
 259 {
 260         struct xfs_inode        *ip = XFS_I(inode);
 261         struct xfs_mount        *mp = ip->i_mount;
 262         struct xfs_trans        *tp;
 263         bool                    update_isize = false;
 264         int                     error, i;
 265         loff_t                  size;
 266
 267         ASSERT(iattr->ia_valid & (ATTR_ATIME|ATTR_CTIME|ATTR_MTIME));
 268
 269         xfs_ilock(ip, XFS_IOLOCK_EXCL);
 270
 271         size = i_size_read(inode);
 272         if ((iattr->ia_valid & ATTR_SIZE) && iattr->ia_size > size) {
 273                 update_isize = true;
 274                 size = iattr->ia_size;
 275         }
 276
 277         for (i = 0; i < nr_maps; i++) {
 278                 u64 start, length, end;
 279
 280                 start = maps[i].offset;
 281                 if (start > size)
 282                         continue;
 283
 284                 end = start + maps[i].length;
 285                 if (end > size)
 286                         end = size;
 287
 288                 length = end - start;
 289                 if (!length)
 290                         continue;
 291
 292                 /*
 293                  * Make sure reads through the pagecache see the new data.
 294                  */
 295                 error = invalidate_inode_pages2_range(inode->i_mapping,
 296                                         start >> PAGE_CACHE_SHIFT,
 297                                         (end - 1) >> PAGE_CACHE_SHIFT);
 298                 WARN_ON_ONCE(error);
 299
 300                 error = xfs_iomap_write_unwritten(ip, start, length);
 301                 if (error)
 302                         goto out_drop_iolock;
 303         }
 304
 305         if (update_isize) {
 306                 error = xfs_pnfs_validate_isize(ip, size);
 307                 if (error)
 308                         goto out_drop_iolock;
 309         }
 310
 311         tp = xfs_trans_alloc(mp, XFS_TRANS_SETATTR_NOT_SIZE);
 312         error = xfs_trans_reserve(tp, &M_RES(mp)->tr_ichange, 0, 0);
 313         if (error) {
 314                 xfs_trans_cancel(tp);
 315                 goto out_drop_iolock;
 316         }
 317
 318         xfs_ilock(ip, XFS_ILOCK_EXCL);
 319         xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 320         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 321
 322         xfs_setattr_time(ip, iattr);
 323         if (update_isize) {
 324                 i_size_write(inode, iattr->ia_size);
 325                 ip->i_d.di_size = iattr->ia_size;
 326         }
 327
 328         xfs_trans_set_sync(tp);
 329         error = xfs_trans_commit(tp);
 330
 331 out_drop_iolock:
 332         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 333         return error;
 334 }