fs/xfs/xfs_pnfs.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2014 Christoph Hellwig.
   4  */
   5 #include "xfs.h"
   6 #include "xfs_shared.h"
   7 #include "xfs_format.h"
   8 #include "xfs_log_format.h"
   9 #include "xfs_trans_resv.h"
  10 #include "xfs_mount.h"
  11 #include "xfs_inode.h"
  12 #include "xfs_trans.h"
  13 #include "xfs_bmap.h"
  14 #include "xfs_iomap.h"
  15 #include "xfs_pnfs.h"
  16
  17 /*
  18  * Ensure that we do not have any outstanding pNFS layouts that can be used by
  19  * clients to directly read from or write to this inode.  This must be called
  20  * before every operation that can remove blocks from the extent map.
  21  * Additionally we call it during the write operation, where aren't concerned
  22  * about exposing unallocated blocks but just want to provide basic
  23  * synchronization between a local writer and pNFS clients.  mmap writes would
  24  * also benefit from this sort of synchronization, but due to the tricky locking
  25  * rules in the page fault path we don't bother.
  26  */
  27 int
  28 xfs_break_leased_layouts(
  29         struct inode            *inode,
  30         uint                    *iolock,
  31         bool                    *did_unlock)
  32 {
  33         struct xfs_inode        *ip = XFS_I(inode);
  34         int                     error;
  35
  36         while ((error = break_layout(inode, false)) == -EWOULDBLOCK) {
  37                 xfs_iunlock(ip, *iolock);
  38                 *did_unlock = true;
  39                 error = break_layout(inode, true);
  40                 *iolock &= ~XFS_IOLOCK_SHARED;
  41                 *iolock |= XFS_IOLOCK_EXCL;
  42                 xfs_ilock(ip, *iolock);
  43         }
  44
  45         return error;
  46 }
  47
  48 /*
  49  * Get a unique ID including its location so that the client can identify
  50  * the exported device.
  51  */
  52 int
  53 xfs_fs_get_uuid(
  54         struct super_block      *sb,
  55         u8                      *buf,
  56         u32                     *len,
  57         u64                     *offset)
  58 {
  59         struct xfs_mount        *mp = XFS_M(sb);
  60
  61         xfs_warn_experimental(mp, XFS_EXPERIMENTAL_PNFS);
  62
  63         if (*len < sizeof(uuid_t))
  64                 return -EINVAL;
  65
  66         memcpy(buf, &mp->m_sb.sb_uuid, sizeof(uuid_t));
  67         *len = sizeof(uuid_t);
  68         *offset = offsetof(struct xfs_dsb, sb_uuid);
  69         return 0;
  70 }
  71
  72 /*
  73  * We cannot use file based VFS helpers such as file_modified() to update
  74  * inode state as we modify the data/metadata in the inode here. Hence we have
  75  * to open code the timestamp updates and SUID/SGID stripping. We also need
  76  * to set the inode prealloc flag to ensure that the extents we allocate are not
  77  * removed if the inode is reclaimed from memory before xfs_fs_block_commit()
  78  * is from the client to indicate that data has been written and the file size
  79  * can be extended.
  80  */
  81 static int
  82 xfs_fs_map_update_inode(
  83         struct xfs_inode        *ip)
  84 {
  85         struct xfs_trans        *tp;
  86         int                     error;
  87
  88         error = xfs_trans_alloc(ip->i_mount, &M_RES(ip->i_mount)->tr_writeid,
  89                         0, 0, 0, &tp);
  90         if (error)
  91                 return error;
  92
  93         xfs_ilock(ip, XFS_ILOCK_EXCL);
  94         xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
  95
  96         VFS_I(ip)->i_mode &= ~S_ISUID;
  97         if (VFS_I(ip)->i_mode & S_IXGRP)
  98                 VFS_I(ip)->i_mode &= ~S_ISGID;
  99         xfs_trans_ichgtime(tp, ip, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG);
 100         ip->i_diflags |= XFS_DIFLAG_PREALLOC;
 101
 102         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 103         return xfs_trans_commit(tp);
 104 }
 105
 106 /*
 107  * Get a layout for the pNFS client.
 108  */
 109 int
 110 xfs_fs_map_blocks(
 111         struct inode            *inode,
 112         loff_t                  offset,
 113         u64                     length,
 114         struct iomap            *iomap,
 115         bool                    write,
 116         u32                     *device_generation)
 117 {
 118         struct xfs_inode        *ip = XFS_I(inode);
 119         struct xfs_mount        *mp = ip->i_mount;
 120         struct xfs_bmbt_irec    imap;
 121         xfs_fileoff_t           offset_fsb, end_fsb;
 122         loff_t                  limit;
 123         int                     bmapi_flags = XFS_BMAPI_ENTIRE;
 124         int                     nimaps = 1;
 125         uint                    lock_flags;
 126         int                     error = 0;
 127         u64                     seq;
 128
 129         if (xfs_is_shutdown(mp))
 130                 return -EIO;
 131
 132         /*
 133          * We can't export inodes residing on the realtime device.  The realtime
 134          * device doesn't have a UUID to identify it, so the client has no way
 135          * to find it.
 136          */
 137         if (XFS_IS_REALTIME_INODE(ip))
 138                 return -ENXIO;
 139
 140         /*
 141          * The pNFS block layout spec actually supports reflink like
 142          * functionality, but the Linux pNFS server doesn't implement it yet.
 143          */
 144         if (xfs_is_reflink_inode(ip))
 145                 return -ENXIO;
 146
 147         /*
 148          * Lock out any other I/O before we flush and invalidate the pagecache,
 149          * and then hand out a layout to the remote system.  This is very
 150          * similar to direct I/O, except that the synchronization is much more
 151          * complicated.  See the comment near xfs_break_leased_layouts
 152          * for a detailed explanation.
 153          */
 154         xfs_ilock(ip, XFS_IOLOCK_EXCL);
 155
 156         error = -EINVAL;
 157         limit = mp->m_super->s_maxbytes;
 158         if (!write)
 159                 limit = max(limit, round_up(i_size_read(inode),
 160                                      inode->i_sb->s_blocksize));
 161         if (offset > limit)
 162                 goto out_unlock;
 163         if (offset > limit - length)
 164                 length = limit - offset;
 165
 166         error = filemap_write_and_wait(inode->i_mapping);
 167         if (error)
 168                 goto out_unlock;
 169         error = invalidate_inode_pages2(inode->i_mapping);
 170         if (WARN_ON_ONCE(error))
 171                 goto out_unlock;
 172
 173         end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + length);
 174         offset_fsb = XFS_B_TO_FSBT(mp, offset);
 175
 176         lock_flags = xfs_ilock_data_map_shared(ip);
 177         error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
 178                                 &imap, &nimaps, bmapi_flags);
 179         seq = xfs_iomap_inode_sequence(ip, 0);
 180
 181         ASSERT(!nimaps || imap.br_startblock != DELAYSTARTBLOCK);
 182
 183         if (!error && write &&
 184             (!nimaps || imap.br_startblock == HOLESTARTBLOCK)) {
 185                 if (offset + length > XFS_ISIZE(ip))
 186                         end_fsb = xfs_iomap_eof_align_last_fsb(ip, end_fsb);
 187                 else if (nimaps && imap.br_startblock == HOLESTARTBLOCK)
 188                         end_fsb = min(end_fsb, imap.br_startoff +
 189                                                imap.br_blockcount);
 190                 xfs_iunlock(ip, lock_flags);
 191
 192                 error = xfs_iomap_write_direct(ip, offset_fsb,
 193                                 end_fsb - offset_fsb, 0, &imap, &seq);
 194                 if (error)
 195                         goto out_unlock;
 196
 197                 /*
 198                  * Ensure the next transaction is committed synchronously so
 199                  * that the blocks allocated and handed out to the client are
 200                  * guaranteed to be present even after a server crash.
 201                  */
 202                 error = xfs_fs_map_update_inode(ip);
 203                 if (!error)
 204                         error = xfs_log_force_inode(ip);
 205                 if (error)
 206                         goto out_unlock;
 207
 208         } else {
 209                 xfs_iunlock(ip, lock_flags);
 210         }
 211         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 212
 213         error = xfs_bmbt_to_iomap(ip, iomap, &imap, 0, 0, seq);
 214         *device_generation = mp->m_generation;
 215         return error;
 216 out_unlock:
 217         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 218         return error;
 219 }
 220
 221 /*
 222  * Ensure the size update falls into a valid allocated block.
 223  */
 224 static int
 225 xfs_pnfs_validate_isize(
 226         struct xfs_inode        *ip,
 227         xfs_off_t               isize)
 228 {
 229         struct xfs_bmbt_irec    imap;
 230         int                     nimaps = 1;
 231         int                     error = 0;
 232
 233         xfs_ilock(ip, XFS_ILOCK_SHARED);
 234         error = xfs_bmapi_read(ip, XFS_B_TO_FSBT(ip->i_mount, isize - 1), 1,
 235                                 &imap, &nimaps, 0);
 236         xfs_iunlock(ip, XFS_ILOCK_SHARED);
 237         if (error)
 238                 return error;
 239
 240         if (imap.br_startblock == HOLESTARTBLOCK ||
 241             imap.br_startblock == DELAYSTARTBLOCK ||
 242             imap.br_state == XFS_EXT_UNWRITTEN)
 243                 return -EIO;
 244         return 0;
 245 }
 246
 247 /*
 248  * Make sure the blocks described by maps are stable on disk.  This includes
 249  * converting any unwritten extents, flushing the disk cache and updating the
 250  * time stamps.
 251  *
 252  * Note that we rely on the caller to always send us a timestamp update so that
 253  * we always commit a transaction here.  If that stops being true we will have
 254  * to manually flush the cache here similar to what the fsync code path does
 255  * for datasyncs on files that have no dirty metadata.
 256  */
 257 int
 258 xfs_fs_commit_blocks(
 259         struct inode            *inode,
 260         struct iomap            *maps,
 261         int                     nr_maps,
 262         struct iattr            *iattr)
 263 {
 264         struct xfs_inode        *ip = XFS_I(inode);
 265         struct xfs_mount        *mp = ip->i_mount;
 266         struct xfs_trans        *tp;
 267         bool                    update_isize = false;
 268         int                     error, i;
 269         loff_t                  size;
 270
 271         ASSERT(iattr->ia_valid & (ATTR_ATIME|ATTR_CTIME|ATTR_MTIME));
 272
 273         xfs_ilock(ip, XFS_IOLOCK_EXCL);
 274
 275         size = i_size_read(inode);
 276         if ((iattr->ia_valid & ATTR_SIZE) && iattr->ia_size > size) {
 277                 update_isize = true;
 278                 size = iattr->ia_size;
 279         }
 280
 281         for (i = 0; i < nr_maps; i++) {
 282                 u64 start, length, end;
 283
 284                 start = maps[i].offset;
 285                 if (start > size)
 286                         continue;
 287
 288                 end = start + maps[i].length;
 289                 if (end > size)
 290                         end = size;
 291
 292                 length = end - start;
 293                 if (!length)
 294                         continue;
 295
 296                 /*
 297                  * Make sure reads through the pagecache see the new data.
 298                  */
 299                 error = invalidate_inode_pages2_range(inode->i_mapping,
 300                                         start >> PAGE_SHIFT,
 301                                         (end - 1) >> PAGE_SHIFT);
 302                 WARN_ON_ONCE(error);
 303
 304                 error = xfs_iomap_write_unwritten(ip, start, length, false);
 305                 if (error)
 306                         goto out_drop_iolock;
 307         }
 308
 309         if (update_isize) {
 310                 error = xfs_pnfs_validate_isize(ip, size);
 311                 if (error)
 312                         goto out_drop_iolock;
 313         }
 314
 315         error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
 316         if (error)
 317                 goto out_drop_iolock;
 318
 319         xfs_ilock(ip, XFS_ILOCK_EXCL);
 320         xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 321         xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 322
 323         ASSERT(!(iattr->ia_valid & (ATTR_UID | ATTR_GID)));
 324         setattr_copy(&nop_mnt_idmap, inode, iattr);
 325         if (update_isize) {
 326                 i_size_write(inode, iattr->ia_size);
 327                 ip->i_disk_size = iattr->ia_size;
 328         }
 329
 330         xfs_trans_set_sync(tp);
 331         error = xfs_trans_commit(tp);
 332
 333 out_drop_iolock:
 334         xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 335         return error;
 336 }