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 /* Called either from qed_check or with table_lock held.  */
  22 static int qed_read_table(BDRVQEDState *s, uint64_t offset, QEDTable *table)
  23 {
  24     QEMUIOVector qiov;
  25     int noffsets;
  26     int i, ret;
  27
  28     struct iovec iov = {
  29         .iov_base = table->offsets,
  30         .iov_len = s->header.cluster_size * s->header.table_size,
  31     };
  32     qemu_iovec_init_external(&qiov, &iov, 1);
  33
  34     trace_qed_read_table(s, offset, table);
  35
  36     if (qemu_in_coroutine()) {
  37         qemu_co_mutex_unlock(&s->table_lock);
  38     }
  39     ret = bdrv_preadv(s->bs->file, offset, &qiov);
  40     if (qemu_in_coroutine()) {
  41         qemu_co_mutex_lock(&s->table_lock);
  42     }
  43     if (ret < 0) {
  44         goto out;
  45     }
  46
  47     /* Byteswap offsets */
  48     noffsets = qiov.size / sizeof(uint64_t);
  49     for (i = 0; i < noffsets; i++) {
  50         table->offsets[i] = le64_to_cpu(table->offsets[i]);
  51     }
  52
  53     ret = 0;
  54 out:
  55     /* Completion */
  56     trace_qed_read_table_cb(s, table, ret);
  57     return ret;
  58 }
  59
  60 /**
  61  * Write out an updated part or all of a table
  62  *
  63  * @s:          QED state
  64  * @offset:     Offset of table in image file, in bytes
  65  * @table:      Table
  66  * @index:      Index of first element
  67  * @n:          Number of elements
  68  * @flush:      Whether or not to sync to disk
  69  *
  70  * Called either from qed_check or with table_lock held.
  71  */
  72 static int qed_write_table(BDRVQEDState *s, uint64_t offset, QEDTable *table,
  73                            unsigned int index, unsigned int n, bool flush)
  74 {
  75     unsigned int sector_mask = BDRV_SECTOR_SIZE / sizeof(uint64_t) - 1;
  76     unsigned int start, end, i;
  77     QEDTable *new_table;
  78     struct iovec iov;
  79     QEMUIOVector qiov;
  80     size_t len_bytes;
  81     int ret;
  82
  83     trace_qed_write_table(s, offset, table, index, n);
  84
  85     /* Calculate indices of the first and one after last elements */
  86     start = index & ~sector_mask;
  87     end = (index + n + sector_mask) & ~sector_mask;
  88
  89     len_bytes = (end - start) * sizeof(uint64_t);
  90
  91     new_table = qemu_blockalign(s->bs, len_bytes);
  92     iov = (struct iovec) {
  93         .iov_base = new_table->offsets,
  94         .iov_len = len_bytes,
  95     };
  96     qemu_iovec_init_external(&qiov, &iov, 1);
  97
  98     /* Byteswap table */
  99     for (i = start; i < end; i++) {
 100         uint64_t le_offset = cpu_to_le64(table->offsets[i]);
 101         new_table->offsets[i - start] = le_offset;
 102     }
 103
 104     /* Adjust for offset into table */
 105     offset += start * sizeof(uint64_t);
 106
 107     if (qemu_in_coroutine()) {
 108         qemu_co_mutex_unlock(&s->table_lock);
 109     }
 110     ret = bdrv_pwritev(s->bs->file, offset, &qiov);
 111     if (qemu_in_coroutine()) {
 112         qemu_co_mutex_lock(&s->table_lock);
 113     }
 114     trace_qed_write_table_cb(s, table, flush, ret);
 115     if (ret < 0) {
 116         goto out;
 117     }
 118
 119     if (flush) {
 120         ret = bdrv_flush(s->bs);
 121         if (ret < 0) {
 122             goto out;
 123         }
 124     }
 125
 126     ret = 0;
 127 out:
 128     qemu_vfree(new_table);
 129     return ret;
 130 }
 131
 132 int qed_read_l1_table_sync(BDRVQEDState *s)
 133 {
 134     return qed_read_table(s, s->header.l1_table_offset, s->l1_table);
 135 }
 136
 137 /* Called either from qed_check or with table_lock held.  */
 138 int qed_write_l1_table(BDRVQEDState *s, unsigned int index, unsigned int n)
 139 {
 140     BLKDBG_EVENT(s->bs->file, BLKDBG_L1_UPDATE);
 141     return qed_write_table(s, s->header.l1_table_offset,
 142                            s->l1_table, index, n, false);
 143 }
 144
 145 int qed_write_l1_table_sync(BDRVQEDState *s, unsigned int index,
 146                             unsigned int n)
 147 {
 148     return qed_write_l1_table(s, index, n);
 149 }
 150
 151 /* Called either from qed_check or with table_lock held.  */
 152 int qed_read_l2_table(BDRVQEDState *s, QEDRequest *request, uint64_t offset)
 153 {
 154     int ret;
 155
 156     qed_unref_l2_cache_entry(request->l2_table);
 157
 158     /* Check for cached L2 entry */
 159     request->l2_table = qed_find_l2_cache_entry(&s->l2_cache, offset);
 160     if (request->l2_table) {
 161         return 0;
 162     }
 163
 164     request->l2_table = qed_alloc_l2_cache_entry(&s->l2_cache);
 165     request->l2_table->table = qed_alloc_table(s);
 166
 167     BLKDBG_EVENT(s->bs->file, BLKDBG_L2_LOAD);
 168     ret = qed_read_table(s, offset, request->l2_table->table);
 169
 170     if (ret) {
 171         /* can't trust loaded L2 table anymore */
 172         qed_unref_l2_cache_entry(request->l2_table);
 173         request->l2_table = NULL;
 174     } else {
 175         request->l2_table->offset = offset;
 176
 177         qed_commit_l2_cache_entry(&s->l2_cache, request->l2_table);
 178
 179         /* This is guaranteed to succeed because we just committed the entry
 180          * to the cache.
 181          */
 182         request->l2_table = qed_find_l2_cache_entry(&s->l2_cache, offset);
 183         assert(request->l2_table != NULL);
 184     }
 185
 186     return ret;
 187 }
 188
 189 int qed_read_l2_table_sync(BDRVQEDState *s, QEDRequest *request, uint64_t offset)
 190 {
 191     return qed_read_l2_table(s, request, offset);
 192 }
 193
 194 /* Called either from qed_check or with table_lock held.  */
 195 int qed_write_l2_table(BDRVQEDState *s, QEDRequest *request,
 196                        unsigned int index, unsigned int n, bool flush)
 197 {
 198     BLKDBG_EVENT(s->bs->file, BLKDBG_L2_UPDATE);
 199     return qed_write_table(s, request->l2_table->offset,
 200                            request->l2_table->table, index, n, flush);
 201 }
 202
 203 int qed_write_l2_table_sync(BDRVQEDState *s, QEDRequest *request,
 204                             unsigned int index, unsigned int n, bool flush)
 205 {
 206     return qed_write_l2_table(s, request, index, n, flush);
 207 }