fs/xfs/xfs_pnfs.c

   1 /*
   2  * Copyright (c) 2014 Christoph Hellwig.
   3  */
   4 #include <linux/iomap.h>
   5 #include "xfs.h"
   6 #include "xfs_format.h"
   7 #include "xfs_log_format.h"
   8 #include "xfs_trans_resv.h"
   9 #include "xfs_sb.h"
  10 #include "xfs_mount.h"
  11 #include "xfs_inode.h"
  12 #include "xfs_trans.h"
  13 #include "xfs_log.h"
  14 #include "xfs_bmap.h"
  15 #include "xfs_bmap_util.h"
  16 #include "xfs_error.h"
  17 #include "xfs_iomap.h"
  18 #include "xfs_shared.h"
  19 #include "xfs_bit.h"
  20 #include "xfs_pnfs.h"
  21
  22 /*
  23  * Ensure that we do not have any outstanding pNFS layouts that can be used by
  24  * clients to directly read from or write to this inode.  This must be called
  25  * before every operation that can remove blocks from the extent map.
  26  * Additionally we call it during the write operation, where aren't concerned
  27  * about exposing unallocated blocks but just want to provide basic
  28  * synchronization between a local writer and pNFS clients.  mmap writes would
  29  * also benefit from this sort of synchronization, but due to the tricky locking
  30  * rules in the page fault path we don't bother.
  31  */
  32 int
  33 xfs_break_layouts(
  34         struct inode            *inode,
  35         uint                    *iolock)
  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                 error = break_layout(inode, true);
  45                 *iolock = XFS_IOLOCK_EXCL;
  46                 xfs_ilock(ip, *iolock);
  47         }
  48
  49         return error;
  50 }
  51
  52 /*
  53  * Get a unique ID including its location so that the client can identify
  54  * the exported device.
  55  */
  56 int
  57 xfs_fs_get_uuid(
  58         struct super_block      *sb,
  59         u8                      *buf,
  60         u32                     *len,
  61         u64                     *offset)
  62 {
  63         struct xfs_mount        *mp = XFS_M(sb);
  64
  65         printk_once(KERN_NOTICE
  66 "XFS (%s): using experimental pNFS feature, use at your own risk!\n",
  67                 mp->m_fsname);
  68
  69         if (*len < sizeof(uuid_t))
  70                 return -EINVAL;
  71
  72         memcpy(buf, &mp->m_sb.sb_uuid, sizeof(uuid_t));
  73         *len = sizeof(uuid_t);
  74         *offset = offsetof(struct xfs_dsb, sb_uuid);
  75         return 0;
  76 }
  77
  78 /*
  79  * Get a layout for the pNFS client.
  80  */
  81 int
  82 xfs_fs_map_blocks(
  83         struct inode            *inode,
  84         loff_t                  offset,
  85         u64                     length,
  86         struct iomap            *iomap,
  87         bool                    write,
  88         u32                     *device_generation)
  89 {
  90         struct xfs_inode        *ip = XFS_I(inode);
  91         struct xfs_mount        *mp = ip->i_mount;
  92         struct xfs_bmbt_irec    imap;
  93         xfs_fileoff_t           offset_fsb, end_fsb;
  94         loff_t                  limit;
  95         int                     bmapi_flags = XFS_BMAPI_ENTIRE;
  96         int                     nimaps = 1;
  97         uint                    lock_flags;
  98         int                     error = 0;
  99
 100         if (XFS_FORCED_SHUTDOWN(mp))
 101                 return -EIO;
 102
 103         /*
 104          * We can't export inodes residing on the realtime device.  The realtime
 105          * device doesn't have a UUID to identify it, so the client has no way
 106          * to find it.
 107          */
 108         if (XFS_IS_REALTIME_INODE(ip))
 109                 return -ENXIO;
 110
 111         /*
 112          * The pNFS block layout spec actually supports reflink like
 113          * functionality, but the Linux pNFS server doesn't implement it yet.
 114          */
 115         if (xfs_is_reflink_inode(ip))
 116                 return -ENXIO;
 117
 118         /*
 119          * Lock out any other I/O before we flush and invalidate the pagecache,
 120          * and then hand out a layout to the remote system.  This is very
 121          * similar to direct I/O, except that the synchronization is much more
 122          * complicated.  See the comment near xfs_break_layouts for a detailed
 123          * explanation.
 124          */
 125         xfs_ilock(ip, XFS_IOLOCK_EXCL);
 126
 127         error = -EINVAL;
 128         limit = mp->m_super->s_maxbytes;
 129         if (!write)
 130                 limit = max(limit, round_up(i_size_read(inode),
 131                                      inode->i_sb->s_blocksize));
 132         if (offset > limit)
 133                 goto out_unlock;
 134         if (offset > limit - length)
 135                 length = limit - offset;
 136
 137         error = filemap_write_and_wait(inode->i_mapping);
 138         if (error)
 139                 goto out_unlock;
 140         error = invalidate_inode_pages2(inode->i_mapping);
 141         if (WARN_ON_ONCE(error))
 142                 return error;
 143
 144         end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + length);
 145         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 146
 147         lock_flags = xfs_ilock_data_map_shared(ip);
 148         error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
 149                                 &imap, &nimaps, bmapi_flags);
 150         xfs_iunlock(ip, lock_flags);
 151
 152         if (error)
 153                 goto out_unlock;
 154
 155         if (write) {
 156                 enum xfs_prealloc_flags flags = 0;
 157
 158                 ASSERT(imap.br_startblock != DELAYSTARTBLOCK);
 159
 160                 if (!nimaps || imap.br_startblock == HOLESTARTBLOCK) {
 161                         /*
 162                          * xfs_iomap_write_direct() expects to take ownership of
 163                          * the shared ilock.
 164                          */
 165                         xfs_ilock(ip, XFS_ILOCK_SHARED);
 166                         error = xfs_iomap_write_direct(ip, offset, length,
 167                                                        &imap, nimaps);
 168                         if (error)
 169                                 goto out_unlock;
 170
 171                         /*
 172                          * Ensure the next transaction is committed
 173                          * synchronously so that the blocks allocated and
 174                          * handed out to the client are guaranteed to be
 175                          * present even after a server crash.
 176                          */
 177                         flags |= XFS_PREALLOC_SET | XFS_PREALLOC_SYNC;
 178                 }
 179
 180                 error = xfs_update_prealloc_flags(ip, flags);
 181                 if (error)
 182                         goto out_unlock;
 183         }
 184         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 185
 186         xfs_bmbt_to_iomap(ip, iomap, &imap);
 187         *device_generation = mp->m_generation;
 188         return error;
 189 out_unlock:
 190         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 191         return error;
 192 }
 193
 194 /*
 195  * Ensure the size update falls into a valid allocated block.
 196  */
 197 static int
 198 xfs_pnfs_validate_isize(
 199         struct xfs_inode        *ip,
 200         xfs_off_t               isize)
 201 {
 202         struct xfs_bmbt_irec    imap;
 203         int                     nimaps = 1;
 204         int                     error = 0;
 205
 206         xfs_ilock(ip, XFS_ILOCK_SHARED);
 207         error = xfs_bmapi_read(ip, XFS_B_TO_FSBT(ip->i_mount, isize - 1), 1,
 208                                 &imap, &nimaps, 0);
 209         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 210         if (error)
 211                 return error;
 212
 213         if (imap.br_startblock == HOLESTARTBLOCK ||
 214             imap.br_startblock == DELAYSTARTBLOCK ||
 215             imap.br_state == XFS_EXT_UNWRITTEN)
 216                 return -EIO;
 217         return 0;
 218 }
 219
 220 /*
 221  * Make sure the blocks described by maps are stable on disk.  This includes
 222  * converting any unwritten extents, flushing the disk cache and updating the
 223  * time stamps.
 224  *
 225  * Note that we rely on the caller to always send us a timestamp update so that
 226  * we always commit a transaction here.  If that stops being true we will have
 227  * to manually flush the cache here similar to what the fsync code path does
 228  * for datasyncs on files that have no dirty metadata.
 229  */
 230 int
 231 xfs_fs_commit_blocks(
 232         struct inode            *inode,
 233         struct iomap            *maps,
 234         int                     nr_maps,
 235         struct iattr            *iattr)
 236 {
 237         struct xfs_inode        *ip = XFS_I(inode);
 238         struct xfs_mount        *mp = ip->i_mount;
 239         struct xfs_trans        *tp;
 240         bool                    update_isize = false;
 241         int                     error, i;
 242         loff_t                  size;
 243
 244         ASSERT(iattr->ia_valid & (ATTR_ATIME|ATTR_CTIME|ATTR_MTIME));
 245
 246         xfs_ilock(ip, XFS_IOLOCK_EXCL);
 247
 248         size = i_size_read(inode);
 249         if ((iattr->ia_valid & ATTR_SIZE) && iattr->ia_size > size) {
 250                 update_isize = true;
 251                 size = iattr->ia_size;
 252         }
 253
 254         for (i = 0; i < nr_maps; i++) {
 255                 u64 start, length, end;
 256
 257                 start = maps[i].offset;
 258                 if (start > size)
 259                         continue;
 260
 261                 end = start + maps[i].length;
 262                 if (end > size)
 263                         end = size;
 264
 265                 length = end - start;
 266                 if (!length)
 267                         continue;
 268
 269                 /*
 270                  * Make sure reads through the pagecache see the new data.
 271                  */
 272                 error = invalidate_inode_pages2_range(inode->i_mapping,
 273                                         start >> PAGE_SHIFT,
 274                                         (end - 1) >> PAGE_SHIFT);
 275                 WARN_ON_ONCE(error);
 276
 277                 error = xfs_iomap_write_unwritten(ip, start, length);
 278                 if (error)
 279                         goto out_drop_iolock;
 280         }
 281
 282         if (update_isize) {
 283                 error = xfs_pnfs_validate_isize(ip, size);
 284                 if (error)
 285                         goto out_drop_iolock;
 286         }
 287
 288         error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
 289         if (error)
 290                 goto out_drop_iolock;
 291
 292         xfs_ilock(ip, XFS_ILOCK_EXCL);
 293         xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 294         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 295
 296         xfs_setattr_time(ip, iattr);
 297         if (update_isize) {
 298                 i_size_write(inode, iattr->ia_size);
 299                 ip->i_d.di_size = iattr->ia_size;
 300         }
 301
 302         xfs_trans_set_sync(tp);
 303         error = xfs_trans_commit(tp);
 304
 305 out_drop_iolock:
 306         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 307         return error;
 308 }