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