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 "block/block-io.h"
  17 #include "trace.h"
  18 #include "qemu/sockets.h" /* for EINPROGRESS on Windows */
  19 #include "qed.h"
  20 #include "qemu/bswap.h"
  21 #include "qemu/memalign.h"
  22
  23 /* Called with table_lock held.  */
  24 static int coroutine_fn qed_read_table(BDRVQEDState *s, uint64_t offset,
  25                                        QEDTable *table)
  26 {
  27     unsigned int bytes = s->header.cluster_size * s->header.table_size;
  28
  29     int noffsets;
  30     int i, ret;
  31
  32     trace_qed_read_table(s, offset, table);
  33
  34     qemu_co_mutex_unlock(&s->table_lock);
  35     ret = bdrv_co_pread(s->bs->file, offset, bytes, table->offsets, 0);
  36     qemu_co_mutex_lock(&s->table_lock);
  37     if (ret < 0) {
  38         goto out;
  39     }
  40
  41     /* Byteswap offsets */
  42     noffsets = bytes / sizeof(uint64_t);
  43     for (i = 0; i < noffsets; i++) {
  44         table->offsets[i] = le64_to_cpu(table->offsets[i]);
  45     }
  46
  47     ret = 0;
  48 out:
  49     /* Completion */
  50     trace_qed_read_table_cb(s, table, ret);
  51     return ret;
  52 }
  53
  54 /**
  55  * Write out an updated part or all of a table
  56  *
  57  * @s:          QED state
  58  * @offset:     Offset of table in image file, in bytes
  59  * @table:      Table
  60  * @index:      Index of first element
  61  * @n:          Number of elements
  62  * @flush:      Whether or not to sync to disk
  63  *
  64  * Called with table_lock held.
  65  */
  66 static int coroutine_fn qed_write_table(BDRVQEDState *s, uint64_t offset,
  67                                         QEDTable *table, unsigned int index,
  68                                         unsigned int n, bool flush)
  69 {
  70     unsigned int sector_mask = BDRV_SECTOR_SIZE / sizeof(uint64_t) - 1;
  71     unsigned int start, end, i;
  72     QEDTable *new_table;
  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
  86     /* Byteswap table */
  87     for (i = start; i < end; i++) {
  88         uint64_t le_offset = cpu_to_le64(table->offsets[i]);
  89         new_table->offsets[i - start] = le_offset;
  90     }
  91
  92     /* Adjust for offset into table */
  93     offset += start * sizeof(uint64_t);
  94
  95     qemu_co_mutex_unlock(&s->table_lock);
  96     ret = bdrv_co_pwrite(s->bs->file, offset, len_bytes, new_table->offsets, 0);
  97     qemu_co_mutex_lock(&s->table_lock);
  98     trace_qed_write_table_cb(s, table, flush, ret);
  99     if (ret < 0) {
 100         goto out;
 101     }
 102
 103     if (flush) {
 104         ret = bdrv_co_flush(s->bs);
 105         if (ret < 0) {
 106             goto out;
 107         }
 108     }
 109
 110     ret = 0;
 111 out:
 112     qemu_vfree(new_table);
 113     return ret;
 114 }
 115
 116 int coroutine_fn qed_read_l1_table_sync(BDRVQEDState *s)
 117 {
 118     return qed_read_table(s, s->header.l1_table_offset, s->l1_table);
 119 }
 120
 121 /* Called with table_lock held.  */
 122 int coroutine_fn qed_write_l1_table(BDRVQEDState *s, unsigned int index,
 123                                     unsigned int n)
 124 {
 125     BLKDBG_EVENT(s->bs->file, BLKDBG_L1_UPDATE);
 126     return qed_write_table(s, s->header.l1_table_offset,
 127                            s->l1_table, index, n, false);
 128 }
 129
 130 int coroutine_fn qed_write_l1_table_sync(BDRVQEDState *s, unsigned int index,
 131                                          unsigned int n)
 132 {
 133     return qed_write_l1_table(s, index, n);
 134 }
 135
 136 /* Called with table_lock held.  */
 137 int coroutine_fn qed_read_l2_table(BDRVQEDState *s, QEDRequest *request,
 138                                    uint64_t offset)
 139 {
 140     int ret;
 141
 142     qed_unref_l2_cache_entry(request->l2_table);
 143
 144     /* Check for cached L2 entry */
 145     request->l2_table = qed_find_l2_cache_entry(&s->l2_cache, offset);
 146     if (request->l2_table) {
 147         return 0;
 148     }
 149
 150     request->l2_table = qed_alloc_l2_cache_entry(&s->l2_cache);
 151     request->l2_table->table = qed_alloc_table(s);
 152
 153     BLKDBG_EVENT(s->bs->file, BLKDBG_L2_LOAD);
 154     ret = qed_read_table(s, offset, request->l2_table->table);
 155
 156     if (ret) {
 157         /* can't trust loaded L2 table anymore */
 158         qed_unref_l2_cache_entry(request->l2_table);
 159         request->l2_table = NULL;
 160     } else {
 161         request->l2_table->offset = offset;
 162
 163         qed_commit_l2_cache_entry(&s->l2_cache, request->l2_table);
 164
 165         /* This is guaranteed to succeed because we just committed the entry
 166          * to the cache.
 167          */
 168         request->l2_table = qed_find_l2_cache_entry(&s->l2_cache, offset);
 169         assert(request->l2_table != NULL);
 170     }
 171
 172     return ret;
 173 }
 174
 175 int coroutine_fn qed_read_l2_table_sync(BDRVQEDState *s, QEDRequest *request,
 176                                         uint64_t offset)
 177 {
 178     return qed_read_l2_table(s, request, offset);
 179 }
 180
 181 /* Called with table_lock held.  */
 182 int coroutine_fn qed_write_l2_table(BDRVQEDState *s, QEDRequest *request,
 183                                     unsigned int index, unsigned int n,
 184                                     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 coroutine_fn qed_write_l2_table_sync(BDRVQEDState *s, QEDRequest *request,
 192                                          unsigned int index, unsigned int n,
 193                                          bool flush)
 194 {
 195     return qed_write_l2_table(s, request, index, n, flush);
 196 }