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_leased_layouts(
  35         struct inode            *inode,
  36         uint                    *iolock,
  37         bool                    *did_unlock)
  38 {
  39         struct xfs_inode        *ip = XFS_I(inode);
  40         int                     error;
  41
  42         while ((error = break_layout(inode, false) == -EWOULDBLOCK)) {
  43                 xfs_iunlock(ip, *iolock);
  44                 *did_unlock = true;
  45                 error = break_layout(inode, true);
  46                 *iolock &= ~XFS_IOLOCK_SHARED;
  47                 *iolock |= XFS_IOLOCK_EXCL;
  48                 xfs_ilock(ip, *iolock);
  49         }
  50
  51         return error;
  52 }
  53
  54 /*
  55  * Get a unique ID including its location so that the client can identify
  56  * the exported device.
  57  */
  58 int
  59 xfs_fs_get_uuid(
  60         struct super_block      *sb,
  61         u8                      *buf,
  62         u32                     *len,
  63         u64                     *offset)
  64 {
  65         struct xfs_mount        *mp = XFS_M(sb);
  66
  67         printk_once(KERN_NOTICE
  68 "XFS (%s): using experimental pNFS feature, use at your own risk!\n",
  69                 mp->m_fsname);
  70
  71         if (*len < sizeof(uuid_t))
  72                 return -EINVAL;
  73
  74         memcpy(buf, &mp->m_sb.sb_uuid, sizeof(uuid_t));
  75         *len = sizeof(uuid_t);
  76         *offset = offsetof(struct xfs_dsb, sb_uuid);
  77         return 0;
  78 }
  79
  80 /*
  81  * Get a layout for the pNFS client.
  82  */
  83 int
  84 xfs_fs_map_blocks(
  85         struct inode            *inode,
  86         loff_t                  offset,
  87         u64                     length,
  88         struct iomap            *iomap,
  89         bool                    write,
  90         u32                     *device_generation)
  91 {
  92         struct xfs_inode        *ip = XFS_I(inode);
  93         struct xfs_mount        *mp = ip->i_mount;
  94         struct xfs_bmbt_irec    imap;
  95         xfs_fileoff_t           offset_fsb, end_fsb;
  96         loff_t                  limit;
  97         int                     bmapi_flags = XFS_BMAPI_ENTIRE;
  98         int                     nimaps = 1;
  99         uint                    lock_flags;
 100         int                     error = 0;
 101
 102         if (XFS_FORCED_SHUTDOWN(mp))
 103                 return -EIO;
 104
 105         /*
 106          * We can't export inodes residing on the realtime device.  The realtime
 107          * device doesn't have a UUID to identify it, so the client has no way
 108          * to find it.
 109          */
 110         if (XFS_IS_REALTIME_INODE(ip))
 111                 return -ENXIO;
 112
 113         /*
 114          * The pNFS block layout spec actually supports reflink like
 115          * functionality, but the Linux pNFS server doesn't implement it yet.
 116          */
 117         if (xfs_is_reflink_inode(ip))
 118                 return -ENXIO;
 119
 120         /*
 121          * Lock out any other I/O before we flush and invalidate the pagecache,
 122          * and then hand out a layout to the remote system.  This is very
 123          * similar to direct I/O, except that the synchronization is much more
 124          * complicated.  See the comment near xfs_break_leased_layouts
 125          * for a detailed explanation.
 126          */
 127         xfs_ilock(ip, XFS_IOLOCK_EXCL);
 128
 129         error = -EINVAL;
 130         limit = mp->m_super->s_maxbytes;
 131         if (!write)
 132                 limit = max(limit, round_up(i_size_read(inode),
 133                                      inode->i_sb->s_blocksize));
 134         if (offset > limit)
 135                 goto out_unlock;
 136         if (offset > limit - length)
 137                 length = limit - offset;
 138
 139         error = filemap_write_and_wait(inode->i_mapping);
 140         if (error)
 141                 goto out_unlock;
 142         error = invalidate_inode_pages2(inode->i_mapping);
 143         if (WARN_ON_ONCE(error))
 144                 return error;
 145
 146         end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + length);
 147         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 148
 149         lock_flags = xfs_ilock_data_map_shared(ip);
 150         error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
 151                                 &imap, &nimaps, bmapi_flags);
 152         xfs_iunlock(ip, lock_flags);
 153
 154         if (error)
 155                 goto out_unlock;
 156
 157         if (write) {
 158                 enum xfs_prealloc_flags flags = 0;
 159
 160                 ASSERT(imap.br_startblock != DELAYSTARTBLOCK);
 161
 162                 if (!nimaps || imap.br_startblock == HOLESTARTBLOCK) {
 163                         /*
 164                          * xfs_iomap_write_direct() expects to take ownership of
 165                          * the shared ilock.
 166                          */
 167                         xfs_ilock(ip, XFS_ILOCK_SHARED);
 168                         error = xfs_iomap_write_direct(ip, offset, length,
 169                                                        &imap, nimaps);
 170                         if (error)
 171                                 goto out_unlock;
 172
 173                         /*
 174                          * Ensure the next transaction is committed
 175                          * synchronously so that the blocks allocated and
 176                          * handed out to the client are guaranteed to be
 177                          * present even after a server crash.
 178                          */
 179                         flags |= XFS_PREALLOC_SET | XFS_PREALLOC_SYNC;
 180                 }
 181
 182                 error = xfs_update_prealloc_flags(ip, flags);
 183                 if (error)
 184                         goto out_unlock;
 185         }
 186         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 187
 188         error = xfs_bmbt_to_iomap(ip, iomap, &imap, false);
 189         *device_generation = mp->m_generation;
 190         return error;
 191 out_unlock:
 192         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 193         return error;
 194 }
 195
 196 /*
 197  * Ensure the size update falls into a valid allocated block.
 198  */
 199 static int
 200 xfs_pnfs_validate_isize(
 201         struct xfs_inode        *ip,
 202         xfs_off_t               isize)
 203 {
 204         struct xfs_bmbt_irec    imap;
 205         int                     nimaps = 1;
 206         int                     error = 0;
 207
 208         xfs_ilock(ip, XFS_ILOCK_SHARED);
 209         error = xfs_bmapi_read(ip, XFS_B_TO_FSBT(ip->i_mount, isize - 1), 1,
 210                                 &imap, &nimaps, 0);
 211         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 212         if (error)
 213                 return error;
 214
 215         if (imap.br_startblock == HOLESTARTBLOCK ||
 216             imap.br_startblock == DELAYSTARTBLOCK ||
 217             imap.br_state == XFS_EXT_UNWRITTEN)
 218                 return -EIO;
 219         return 0;
 220 }
 221
 222 /*
 223  * Make sure the blocks described by maps are stable on disk.  This includes
 224  * converting any unwritten extents, flushing the disk cache and updating the
 225  * time stamps.
 226  *
 227  * Note that we rely on the caller to always send us a timestamp update so that
 228  * we always commit a transaction here.  If that stops being true we will have
 229  * to manually flush the cache here similar to what the fsync code path does
 230  * for datasyncs on files that have no dirty metadata.
 231  */
 232 int
 233 xfs_fs_commit_blocks(
 234         struct inode            *inode,
 235         struct iomap            *maps,
 236         int                     nr_maps,
 237         struct iattr            *iattr)
 238 {
 239         struct xfs_inode        *ip = XFS_I(inode);
 240         struct xfs_mount        *mp = ip->i_mount;
 241         struct xfs_trans        *tp;
 242         bool                    update_isize = false;
 243         int                     error, i;
 244         loff_t                  size;
 245
 246         ASSERT(iattr->ia_valid & (ATTR_ATIME|ATTR_CTIME|ATTR_MTIME));
 247
 248         xfs_ilock(ip, XFS_IOLOCK_EXCL);
 249
 250         size = i_size_read(inode);
 251         if ((iattr->ia_valid & ATTR_SIZE) && iattr->ia_size > size) {
 252                 update_isize = true;
 253                 size = iattr->ia_size;
 254         }
 255
 256         for (i = 0; i < nr_maps; i++) {
 257                 u64 start, length, end;
 258
 259                 start = maps[i].offset;
 260                 if (start > size)
 261                         continue;
 262
 263                 end = start + maps[i].length;
 264                 if (end > size)
 265                         end = size;
 266
 267                 length = end - start;
 268                 if (!length)
 269                         continue;
 270
 271                 /*
 272                  * Make sure reads through the pagecache see the new data.
 273                  */
 274                 error = invalidate_inode_pages2_range(inode->i_mapping,
 275                                         start >> PAGE_SHIFT,
 276                                         (end - 1) >> PAGE_SHIFT);
 277                 WARN_ON_ONCE(error);
 278
 279                 error = xfs_iomap_write_unwritten(ip, start, length, false);
 280                 if (error)
 281                         goto out_drop_iolock;
 282         }
 283
 284         if (update_isize) {
 285                 error = xfs_pnfs_validate_isize(ip, size);
 286                 if (error)
 287                         goto out_drop_iolock;
 288         }
 289
 290         error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
 291         if (error)
 292                 goto out_drop_iolock;
 293
 294         xfs_ilock(ip, XFS_ILOCK_EXCL);
 295         xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 296         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 297
 298         xfs_setattr_time(ip, iattr);
 299         if (update_isize) {
 300                 i_size_write(inode, iattr->ia_size);
 301                 ip->i_d.di_size = iattr->ia_size;
 302         }
 303
 304         xfs_trans_set_sync(tp);
 305         error = xfs_trans_commit(tp);
 306
 307 out_drop_iolock:
 308         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 309         return error;
 310 }