linux/fs/xfs/xfs_pnfs.c
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   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 */
  27int
  28xfs_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 */
  52int
  53xfs_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_notice_once(mp,
  62"Using experimental pNFS feature, use at your own risk!");
  63
  64        if (*len < sizeof(uuid_t))
  65                return -EINVAL;
  66
  67        memcpy(buf, &mp->m_sb.sb_uuid, sizeof(uuid_t));
  68        *len = sizeof(uuid_t);
  69        *offset = offsetof(struct xfs_dsb, sb_uuid);
  70        return 0;
  71}
  72
  73/*
  74 * Get a layout for the pNFS client.
  75 */
  76int
  77xfs_fs_map_blocks(
  78        struct inode            *inode,
  79        loff_t                  offset,
  80        u64                     length,
  81        struct iomap            *iomap,
  82        bool                    write,
  83        u32                     *device_generation)
  84{
  85        struct xfs_inode        *ip = XFS_I(inode);
  86        struct xfs_mount        *mp = ip->i_mount;
  87        struct xfs_bmbt_irec    imap;
  88        xfs_fileoff_t           offset_fsb, end_fsb;
  89        loff_t                  limit;
  90        int                     bmapi_flags = XFS_BMAPI_ENTIRE;
  91        int                     nimaps = 1;
  92        uint                    lock_flags;
  93        int                     error = 0;
  94
  95        if (XFS_FORCED_SHUTDOWN(mp))
  96                return -EIO;
  97
  98        /*
  99         * We can't export inodes residing on the realtime device.  The realtime
 100         * device doesn't have a UUID to identify it, so the client has no way
 101         * to find it.
 102         */
 103        if (XFS_IS_REALTIME_INODE(ip))
 104                return -ENXIO;
 105
 106        /*
 107         * The pNFS block layout spec actually supports reflink like
 108         * functionality, but the Linux pNFS server doesn't implement it yet.
 109         */
 110        if (xfs_is_reflink_inode(ip))
 111                return -ENXIO;
 112
 113        /*
 114         * Lock out any other I/O before we flush and invalidate the pagecache,
 115         * and then hand out a layout to the remote system.  This is very
 116         * similar to direct I/O, except that the synchronization is much more
 117         * complicated.  See the comment near xfs_break_leased_layouts
 118         * for a detailed explanation.
 119         */
 120        xfs_ilock(ip, XFS_IOLOCK_EXCL);
 121
 122        error = -EINVAL;
 123        limit = mp->m_super->s_maxbytes;
 124        if (!write)
 125                limit = max(limit, round_up(i_size_read(inode),
 126                                     inode->i_sb->s_blocksize));
 127        if (offset > limit)
 128                goto out_unlock;
 129        if (offset > limit - length)
 130                length = limit - offset;
 131
 132        error = filemap_write_and_wait(inode->i_mapping);
 133        if (error)
 134                goto out_unlock;
 135        error = invalidate_inode_pages2(inode->i_mapping);
 136        if (WARN_ON_ONCE(error))
 137                return error;
 138
 139        end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + length);
 140        offset_fsb = XFS_B_TO_FSBT(mp, offset);
 141
 142        lock_flags = xfs_ilock_data_map_shared(ip);
 143        error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
 144                                &imap, &nimaps, bmapi_flags);
 145
 146        ASSERT(!nimaps || imap.br_startblock != DELAYSTARTBLOCK);
 147
 148        if (!error && write &&
 149            (!nimaps || imap.br_startblock == HOLESTARTBLOCK)) {
 150                if (offset + length > XFS_ISIZE(ip))
 151                        end_fsb = xfs_iomap_eof_align_last_fsb(ip, end_fsb);
 152                else if (nimaps && imap.br_startblock == HOLESTARTBLOCK)
 153                        end_fsb = min(end_fsb, imap.br_startoff +
 154                                               imap.br_blockcount);
 155                xfs_iunlock(ip, lock_flags);
 156
 157                error = xfs_iomap_write_direct(ip, offset_fsb,
 158                                end_fsb - offset_fsb, &imap);
 159                if (error)
 160                        goto out_unlock;
 161
 162                /*
 163                 * Ensure the next transaction is committed synchronously so
 164                 * that the blocks allocated and handed out to the client are
 165                 * guaranteed to be present even after a server crash.
 166                 */
 167                error = xfs_update_prealloc_flags(ip,
 168                                XFS_PREALLOC_SET | XFS_PREALLOC_SYNC);
 169                if (error)
 170                        goto out_unlock;
 171        } else {
 172                xfs_iunlock(ip, lock_flags);
 173        }
 174        xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 175
 176        error = xfs_bmbt_to_iomap(ip, iomap, &imap, 0);
 177        *device_generation = mp->m_generation;
 178        return error;
 179out_unlock:
 180        xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 181        return error;
 182}
 183
 184/*
 185 * Ensure the size update falls into a valid allocated block.
 186 */
 187static int
 188xfs_pnfs_validate_isize(
 189        struct xfs_inode        *ip,
 190        xfs_off_t               isize)
 191{
 192        struct xfs_bmbt_irec    imap;
 193        int                     nimaps = 1;
 194        int                     error = 0;
 195
 196        xfs_ilock(ip, XFS_ILOCK_SHARED);
 197        error = xfs_bmapi_read(ip, XFS_B_TO_FSBT(ip->i_mount, isize - 1), 1,
 198                                &imap, &nimaps, 0);
 199        xfs_iunlock(ip, XFS_ILOCK_SHARED);
 200        if (error)
 201                return error;
 202
 203        if (imap.br_startblock == HOLESTARTBLOCK ||
 204            imap.br_startblock == DELAYSTARTBLOCK ||
 205            imap.br_state == XFS_EXT_UNWRITTEN)
 206                return -EIO;
 207        return 0;
 208}
 209
 210/*
 211 * Make sure the blocks described by maps are stable on disk.  This includes
 212 * converting any unwritten extents, flushing the disk cache and updating the
 213 * time stamps.
 214 *
 215 * Note that we rely on the caller to always send us a timestamp update so that
 216 * we always commit a transaction here.  If that stops being true we will have
 217 * to manually flush the cache here similar to what the fsync code path does
 218 * for datasyncs on files that have no dirty metadata.
 219 */
 220int
 221xfs_fs_commit_blocks(
 222        struct inode            *inode,
 223        struct iomap            *maps,
 224        int                     nr_maps,
 225        struct iattr            *iattr)
 226{
 227        struct xfs_inode        *ip = XFS_I(inode);
 228        struct xfs_mount        *mp = ip->i_mount;
 229        struct xfs_trans        *tp;
 230        bool                    update_isize = false;
 231        int                     error, i;
 232        loff_t                  size;
 233
 234        ASSERT(iattr->ia_valid & (ATTR_ATIME|ATTR_CTIME|ATTR_MTIME));
 235
 236        xfs_ilock(ip, XFS_IOLOCK_EXCL);
 237
 238        size = i_size_read(inode);
 239        if ((iattr->ia_valid & ATTR_SIZE) && iattr->ia_size > size) {
 240                update_isize = true;
 241                size = iattr->ia_size;
 242        }
 243
 244        for (i = 0; i < nr_maps; i++) {
 245                u64 start, length, end;
 246
 247                start = maps[i].offset;
 248                if (start > size)
 249                        continue;
 250
 251                end = start + maps[i].length;
 252                if (end > size)
 253                        end = size;
 254
 255                length = end - start;
 256                if (!length)
 257                        continue;
 258        
 259                /*
 260                 * Make sure reads through the pagecache see the new data.
 261                 */
 262                error = invalidate_inode_pages2_range(inode->i_mapping,
 263                                        start >> PAGE_SHIFT,
 264                                        (end - 1) >> PAGE_SHIFT);
 265                WARN_ON_ONCE(error);
 266
 267                error = xfs_iomap_write_unwritten(ip, start, length, false);
 268                if (error)
 269                        goto out_drop_iolock;
 270        }
 271
 272        if (update_isize) {
 273                error = xfs_pnfs_validate_isize(ip, size);
 274                if (error)
 275                        goto out_drop_iolock;
 276        }
 277
 278        error = xfs_trans_alloc(mp, &M_RES(mp)->tr_ichange, 0, 0, 0, &tp);
 279        if (error)
 280                goto out_drop_iolock;
 281
 282        xfs_ilock(ip, XFS_ILOCK_EXCL);
 283        xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
 284        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
 285
 286        xfs_setattr_time(ip, iattr);
 287        if (update_isize) {
 288                i_size_write(inode, iattr->ia_size);
 289                ip->i_d.di_size = iattr->ia_size;
 290        }
 291
 292        xfs_trans_set_sync(tp);
 293        error = xfs_trans_commit(tp);
 294
 295out_drop_iolock:
 296        xfs_iunlock(ip, XFS_IOLOCK_EXCL);
 297        return error;
 298}
 299