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