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 #include "qemu/memalign.h"
  21
  22 /* Called with table_lock held.  */
  23 static int coroutine_fn qed_read_table(BDRVQEDState *s, uint64_t offset,
  24                                        QEDTable *table)
  25 {
  26     unsigned int bytes = s->header.cluster_size * s->header.table_size;
  27
  28     int noffsets;
  29     int i, ret;
  30
  31     trace_qed_read_table(s, offset, table);
  32
  33     qemu_co_mutex_unlock(&s->table_lock);
  34     ret = bdrv_co_pread(s->bs->file, offset, bytes, table->offsets, 0);
  35     qemu_co_mutex_lock(&s->table_lock);
  36     if (ret < 0) {
  37         goto out;
  38     }
  39
  40     /* Byteswap offsets */
  41     noffsets = bytes / sizeof(uint64_t);
  42     for (i = 0; i < noffsets; i++) {
  43         table->offsets[i] = le64_to_cpu(table->offsets[i]);
  44     }
  45
  46     ret = 0;
  47 out:
  48     /* Completion */
  49     trace_qed_read_table_cb(s, table, ret);
  50     return ret;
  51 }
  52
  53 /**
  54  * Write out an updated part or all of a table
  55  *
  56  * @s:          QED state
  57  * @offset:     Offset of table in image file, in bytes
  58  * @table:      Table
  59  * @index:      Index of first element
  60  * @n:          Number of elements
  61  * @flush:      Whether or not to sync to disk
  62  *
  63  * Called with table_lock held.
  64  */
  65 static int coroutine_fn qed_write_table(BDRVQEDState *s, uint64_t offset,
  66                                         QEDTable *table, unsigned int index,
  67                                         unsigned int n, bool flush)
  68 {
  69     unsigned int sector_mask = BDRV_SECTOR_SIZE / sizeof(uint64_t) - 1;
  70     unsigned int start, end, i;
  71     QEDTable *new_table;
  72     size_t len_bytes;
  73     int ret;
  74
  75     trace_qed_write_table(s, offset, table, index, n);
  76
  77     /* Calculate indices of the first and one after last elements */
  78     start = index & ~sector_mask;
  79     end = (index + n + sector_mask) & ~sector_mask;
  80
  81     len_bytes = (end - start) * sizeof(uint64_t);
  82
  83     new_table = qemu_blockalign(s->bs, len_bytes);
  84
  85     /* Byteswap table */
  86     for (i = start; i < end; i++) {
  87         uint64_t le_offset = cpu_to_le64(table->offsets[i]);
  88         new_table->offsets[i - start] = le_offset;
  89     }
  90
  91     /* Adjust for offset into table */
  92     offset += start * sizeof(uint64_t);
  93
  94     qemu_co_mutex_unlock(&s->table_lock);
  95     ret = bdrv_co_pwrite(s->bs->file, offset, len_bytes, new_table->offsets, 0);
  96     qemu_co_mutex_lock(&s->table_lock);
  97     trace_qed_write_table_cb(s, table, flush, ret);
  98     if (ret < 0) {
  99         goto out;
 100     }
 101
 102     if (flush) {
 103         ret = bdrv_co_flush(s->bs);
 104         if (ret < 0) {
 105             goto out;
 106         }
 107     }
 108
 109     ret = 0;
 110 out:
 111     qemu_vfree(new_table);
 112     return ret;
 113 }
 114
 115 int coroutine_fn qed_read_l1_table_sync(BDRVQEDState *s)
 116 {
 117     return qed_read_table(s, s->header.l1_table_offset, s->l1_table);
 118 }
 119
 120 /* Called with table_lock held.  */
 121 int coroutine_fn qed_write_l1_table(BDRVQEDState *s, unsigned int index,
 122                                     unsigned int n)
 123 {
 124     BLKDBG_EVENT(s->bs->file, BLKDBG_L1_UPDATE);
 125     return qed_write_table(s, s->header.l1_table_offset,
 126                            s->l1_table, index, n, false);
 127 }
 128
 129 int coroutine_fn qed_write_l1_table_sync(BDRVQEDState *s, unsigned int index,
 130                                          unsigned int n)
 131 {
 132     return qed_write_l1_table(s, index, n);
 133 }
 134
 135 /* Called with table_lock held.  */
 136 int coroutine_fn qed_read_l2_table(BDRVQEDState *s, QEDRequest *request,
 137                                    uint64_t offset)
 138 {
 139     int ret;
 140
 141     qed_unref_l2_cache_entry(request->l2_table);
 142
 143     /* Check for cached L2 entry */
 144     request->l2_table = qed_find_l2_cache_entry(&s->l2_cache, offset);
 145     if (request->l2_table) {
 146         return 0;
 147     }
 148
 149     request->l2_table = qed_alloc_l2_cache_entry(&s->l2_cache);
 150     request->l2_table->table = qed_alloc_table(s);
 151
 152     BLKDBG_EVENT(s->bs->file, BLKDBG_L2_LOAD);
 153     ret = qed_read_table(s, offset, request->l2_table->table);
 154
 155     if (ret) {
 156         /* can't trust loaded L2 table anymore */
 157         qed_unref_l2_cache_entry(request->l2_table);
 158         request->l2_table = NULL;
 159     } else {
 160         request->l2_table->offset = offset;
 161
 162         qed_commit_l2_cache_entry(&s->l2_cache, request->l2_table);
 163
 164         /* This is guaranteed to succeed because we just committed the entry
 165          * to the cache.
 166          */
 167         request->l2_table = qed_find_l2_cache_entry(&s->l2_cache, offset);
 168         assert(request->l2_table != NULL);
 169     }
 170
 171     return ret;
 172 }
 173
 174 int coroutine_fn qed_read_l2_table_sync(BDRVQEDState *s, QEDRequest *request,
 175                                         uint64_t offset)
 176 {
 177     return qed_read_l2_table(s, request, offset);
 178 }
 179
 180 /* Called with table_lock held.  */
 181 int coroutine_fn qed_write_l2_table(BDRVQEDState *s, QEDRequest *request,
 182                                     unsigned int index, unsigned int n,
 183                                     bool flush)
 184 {
 185     BLKDBG_EVENT(s->bs->file, BLKDBG_L2_UPDATE);
 186     return qed_write_table(s, request->l2_table->offset,
 187                            request->l2_table->table, index, n, flush);
 188 }
 189
 190 int coroutine_fn qed_write_l2_table_sync(BDRVQEDState *s, QEDRequest *request,
 191                                          unsigned int index, unsigned int n,
 192                                          bool flush)
 193 {
 194     return qed_write_l2_table(s, request, index, n, flush);
 195 }