block/qed-table.c

   1 /*
   2  * QEMU Enhanced Disk Format Table I/O
   3  *
   4  * Copyright IBM, Corp. 2010
   5  *
   6  * Authors:
   7  *  Stefan Hajnoczi   <stefanha@linux.vnet.ibm.com>
   8  *  Anthony Liguori   <aliguori@us.ibm.com>
   9  *
  10  * This work is licensed under the terms of the GNU LGPL, version 2 or later.
  11  * See the COPYING.LIB file in the top-level directory.
  12  *
  13  */
  14
  15 #include "qemu/osdep.h"
  16 #include "trace.h"
  17 #include "qemu/sockets.h" /* for EINPROGRESS on Windows */
  18 #include "qed.h"
  19 #include "qemu/bswap.h"
  20
  21 static int qed_read_table(BDRVQEDState *s, uint64_t offset, QEDTable *table)
  22 {
  23     QEMUIOVector qiov;
  24     int noffsets;
  25     int i, ret;
  26
  27     struct iovec iov = {
  28         .iov_base = table->offsets,
  29         .iov_len = s->header.cluster_size * s->header.table_size,
  30     };
  31     qemu_iovec_init_external(&qiov, &iov, 1);
  32
  33     trace_qed_read_table(s, offset, table);
  34
  35     ret = bdrv_preadv(s->bs->file, offset, &qiov);
  36     if (ret < 0) {
  37         goto out;
  38     }
  39
  40     /* Byteswap offsets */
  41     qed_acquire(s);
  42     noffsets = qiov.size / sizeof(uint64_t);
  43     for (i = 0; i < noffsets; i++) {
  44         table->offsets[i] = le64_to_cpu(table->offsets[i]);
  45     }
  46     qed_release(s);
  47
  48     ret = 0;
  49 out:
  50     /* Completion */
  51     trace_qed_read_table_cb(s, table, ret);
  52     return ret;
  53 }
  54
  55 /**
  56  * Write out an updated part or all of a table
  57  *
  58  * @s:          QED state
  59  * @offset:     Offset of table in image file, in bytes
  60  * @table:      Table
  61  * @index:      Index of first element
  62  * @n:          Number of elements
  63  * @flush:      Whether or not to sync to disk
  64  */
  65 static int qed_write_table(BDRVQEDState *s, uint64_t offset, QEDTable *table,
  66                            unsigned int index, unsigned int n, bool flush)
  67 {
  68     unsigned int sector_mask = BDRV_SECTOR_SIZE / sizeof(uint64_t) - 1;
  69     unsigned int start, end, i;
  70     QEDTable *new_table;
  71     struct iovec iov;
  72     QEMUIOVector qiov;
  73     size_t len_bytes;
  74     int ret;
  75
  76     trace_qed_write_table(s, offset, table, index, n);
  77
  78     /* Calculate indices of the first and one after last elements */
  79     start = index & ~sector_mask;
  80     end = (index + n + sector_mask) & ~sector_mask;
  81
  82     len_bytes = (end - start) * sizeof(uint64_t);
  83
  84     new_table = qemu_blockalign(s->bs, len_bytes);
  85     iov = (struct iovec) {
  86         .iov_base = new_table->offsets,
  87         .iov_len = len_bytes,
  88     };
  89     qemu_iovec_init_external(&qiov, &iov, 1);
  90
  91     /* Byteswap table */
  92     for (i = start; i < end; i++) {
  93         uint64_t le_offset = cpu_to_le64(table->offsets[i]);
  94         new_table->offsets[i - start] = le_offset;
  95     }
  96
  97     /* Adjust for offset into table */
  98     offset += start * sizeof(uint64_t);
  99
 100     ret = bdrv_pwritev(s->bs->file, offset, &qiov);
 101     trace_qed_write_table_cb(s, table, flush, ret);
 102     if (ret < 0) {
 103         goto out;
 104     }
 105
 106     if (flush) {
 107         qed_acquire(s);
 108         ret = bdrv_flush(s->bs);
 109         qed_release(s);
 110         if (ret < 0) {
 111             goto out;
 112         }
 113     }
 114
 115     ret = 0;
 116 out:
 117     qemu_vfree(new_table);
 118     return ret;
 119 }
 120
 121 int qed_read_l1_table_sync(BDRVQEDState *s)
 122 {
 123     return qed_read_table(s, s->header.l1_table_offset, s->l1_table);
 124 }
 125
 126 int qed_write_l1_table(BDRVQEDState *s, unsigned int index, unsigned int n)
 127 {
 128     BLKDBG_EVENT(s->bs->file, BLKDBG_L1_UPDATE);
 129     return qed_write_table(s, s->header.l1_table_offset,
 130                            s->l1_table, index, n, false);
 131 }
 132
 133 int qed_write_l1_table_sync(BDRVQEDState *s, unsigned int index,
 134                             unsigned int n)
 135 {
 136     return qed_write_l1_table(s, index, n);
 137 }
 138
 139 int qed_read_l2_table(BDRVQEDState *s, QEDRequest *request, uint64_t offset)
 140 {
 141     int ret;
 142
 143     qed_unref_l2_cache_entry(request->l2_table);
 144
 145     /* Check for cached L2 entry */
 146     request->l2_table = qed_find_l2_cache_entry(&s->l2_cache, offset);
 147     if (request->l2_table) {
 148         return 0;
 149     }
 150
 151     request->l2_table = qed_alloc_l2_cache_entry(&s->l2_cache);
 152     request->l2_table->table = qed_alloc_table(s);
 153
 154     BLKDBG_EVENT(s->bs->file, BLKDBG_L2_LOAD);
 155     ret = qed_read_table(s, offset, request->l2_table->table);
 156
 157     qed_acquire(s);
 158     if (ret) {
 159         /* can't trust loaded L2 table anymore */
 160         qed_unref_l2_cache_entry(request->l2_table);
 161         request->l2_table = NULL;
 162     } else {
 163         request->l2_table->offset = offset;
 164
 165         qed_commit_l2_cache_entry(&s->l2_cache, request->l2_table);
 166
 167         /* This is guaranteed to succeed because we just committed the entry
 168          * to the cache.
 169          */
 170         request->l2_table = qed_find_l2_cache_entry(&s->l2_cache, offset);
 171         assert(request->l2_table != NULL);
 172     }
 173     qed_release(s);
 174
 175     return ret;
 176 }
 177
 178 int qed_read_l2_table_sync(BDRVQEDState *s, QEDRequest *request, uint64_t offset)
 179 {
 180     return qed_read_l2_table(s, request, offset);
 181 }
 182
 183 int qed_write_l2_table(BDRVQEDState *s, QEDRequest *request,
 184                        unsigned int index, unsigned int n, bool flush)
 185 {
 186     BLKDBG_EVENT(s->bs->file, BLKDBG_L2_UPDATE);
 187     return qed_write_table(s, request->l2_table->offset,
 188                            request->l2_table->table, index, n, flush);
 189 }
 190
 191 int qed_write_l2_table_sync(BDRVQEDState *s, QEDRequest *request,
 192                             unsigned int index, unsigned int n, bool flush)
 193 {
 194     return qed_write_l2_table(s, request, index, n, flush);
 195 }