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          * The pNFS block layout spec actually supports reflink like
 118          * functionality, but the Linux pNFS server doesn't implement it yet.
 119          */
 120         if (xfs_is_reflink_inode(ip))
 121                 return -ENXIO;
 122
 123         /*
 124          * Lock out any other I/O before we flush and invalidate the pagecache,
 125          * and then hand out a layout to the remote system.  This is very
 126          * similar to direct I/O, except that the synchronization is much more
 127          * complicated.  See the comment near xfs_break_layouts for a detailed
 128          * explanation.
 129          */
 130         xfs_ilock(ip, XFS_IOLOCK_EXCL);
 131
 132         error = -EINVAL;
 133         limit = mp->m_super->s_maxbytes;
 134         if (!write)
 135                 limit = max(limit, round_up(i_size_read(inode),
 136                                      inode->i_sb->s_blocksize));
 137         if (offset > limit)
 138                 goto out_unlock;
 139         if (offset > limit - length)
 140                 length = limit - offset;
 141
 142         error = filemap_write_and_wait(inode->i_mapping);
 143         if (error)
 144                 goto out_unlock;
 145         error = invalidate_inode_pages2(inode->i_mapping);
 146         if (WARN_ON_ONCE(error))
 147                 return error;
 148
 149         end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + length);
 150         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 151
 152         lock_flags = xfs_ilock_data_map_shared(ip);
 153         error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
 154                                 &imap, &nimaps, bmapi_flags);
 155         xfs_iunlock(ip, lock_flags);
 156
 157         if (error)
 158                 goto out_unlock;
 159
 160         if (write) {
 161                 enum xfs_prealloc_flags flags = 0;
 162
 163                 ASSERT(imap.br_startblock != DELAYSTARTBLOCK);
 164
 165                 if (!nimaps || imap.br_startblock == HOLESTARTBLOCK) {
 166                         /*
 167                          * xfs_iomap_write_direct() expects to take ownership of
 168                          * the shared ilock.
 169                          */
 170                         xfs_ilock(ip, XFS_ILOCK_SHARED);
 171                         error = xfs_iomap_write_direct(ip, offset, length,
 172                                                        &imap, nimaps);
 173                         if (error)
 174                                 goto out_unlock;
 175
 176                         /*
 177                          * Ensure the next transaction is committed
 178                          * synchronously so that the blocks allocated and
 179                          * handed out to the client are guaranteed to be
 180                          * present even after a server crash.
 181                          */
 182                         flags |= XFS_PREALLOC_SET | XFS_PREALLOC_SYNC;
 183                 }
 184
 185                 error = xfs_update_prealloc_flags(ip, flags);
 186                 if (error)
 187                         goto out_unlock;
 188         }
 189         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 190
 191         xfs_bmbt_to_iomap(ip, iomap, &imap);
 192         *device_generation = mp->m_generation;
 193         return error;
 194 out_unlock:
 195         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 196         return error;
 197 }
 198
 199 /*
 200  * Ensure the size update falls into a valid allocated block.
 201  */
 202 static int
 203 xfs_pnfs_validate_isize(
 204         struct xfs_inode        *ip,
 205         xfs_off_t               isize)
 206 {
 207         struct xfs_bmbt_irec    imap;
 208         int                     nimaps = 1;
 209         int                     error = 0;
 210
 211         xfs_ilock(ip, XFS_ILOCK_SHARED);
 212         error = xfs_bmapi_read(ip, XFS_B_TO_FSBT(ip->i_mount, isize - 1), 1,
 213                                 &imap, &nimaps, 0);
 214         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 215         if (error)
 216                 return error;
 217
 218         if (imap.br_startblock == HOLESTARTBLOCK ||
 219             imap.br_startblock == DELAYSTARTBLOCK ||
 220             imap.br_state == XFS_EXT_UNWRITTEN)
 221                 return -EIO;
 222         return 0;
 223 }
 224
 225 /*
 226  * Make sure the blocks described by maps are stable on disk.  This includes
 227  * converting any unwritten extents, flushing the disk cache and updating the
 228  * time stamps.
 229  *
 230  * Note that we rely on the caller to always send us a timestamp update so that
 231  * we always commit a transaction here.  If that stops being true we will have
 232  * to manually flush the cache here similar to what the fsync code path does
 233  * for datasyncs on files that have no dirty metadata.
 234  */
 235 int
 236 xfs_fs_commit_blocks(
 237         struct inode            *inode,
 238         struct iomap            *maps,
 239         int                     nr_maps,
 240         struct iattr            *iattr)
 241 {
 242         struct xfs_inode        *ip = XFS_I(inode);
 243         struct xfs_mount        *mp = ip->i_mount;
 244         struct xfs_trans        *tp;
 245         bool                    update_isize = false;
 246         int                     error, i;
 247         loff_t                  size;
 248
 249         ASSERT(iattr->ia_valid & (ATTR_ATIME|ATTR_CTIME|ATTR_MTIME));
 250
 251         xfs_ilock(ip, XFS_IOLOCK_EXCL);
 252
 253         size = i_size_read(inode);
 254         if ((iattr->ia_valid & ATTR_SIZE) && iattr->ia_size > size) {
 255                 update_isize = true;
 256                 size = iattr->ia_size;
 257         }
 258
 259         for (i = 0; i < nr_maps; i++) {
 260                 u64 start, length, end;
 261
 262                 start = maps[i].offset;
 263                 if (start > size)
 264                         continue;
 265
 266                 end = start + maps[i].length;
 267                 if (end > size)
 268                         end = size;
 269
 270                 length = end - start;
 271                 if (!length)
 272                         continue;
 273
 274                 /*
 275                  * Make sure reads through the pagecache see the new data.
 276                  */
 277                 error = invalidate_inode_pages2_range(inode->i_mapping,
 278                                         start >> PAGE_SHIFT,
 279                                         (end - 1) >> PAGE_SHIFT);
 280                 WARN_ON_ONCE(error);
 281
 282                 error = xfs_iomap_write_unwritten(ip, start, length, false);
 283                 if (error)
 284                         goto out_drop_iolock;
 285         }
 286
 287         if (update_isize) {
 288                 error = xfs_pnfs_validate_isize(ip, size);
 289                 if (error)
 290                         goto out_drop_iolock;
 291         }
 292
 293         error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
 294         if (error)
 295                 goto out_drop_iolock;
 296
 297         xfs_ilock(ip, XFS_ILOCK_EXCL);
 298         xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 299         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 300
 301         xfs_setattr_time(ip, iattr);
 302         if (update_isize) {
 303                 i_size_write(inode, iattr->ia_size);
 304                 ip->i_d.di_size = iattr->ia_size;
 305         }
 306
 307         xfs_trans_set_sync(tp);
 308         error = xfs_trans_commit(tp);
 309
 310 out_drop_iolock:
 311         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 312         return error;
 313 }