qemu

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/*
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 * QEMU Enhanced Disk Format Table I/O
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 *
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 * Copyright IBM, Corp. 2010
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 *
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 * Authors:
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 *  Stefan Hajnoczi   <stefanha@linux.vnet.ibm.com>
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 *  Anthony Liguori   <aliguori@us.ibm.com>
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 *
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 * This work is licensed under the terms of the GNU LGPL, version 2 or later.
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 * See the COPYING.LIB file in the top-level directory.
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 *
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 */
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#include "qemu/osdep.h"
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#include "block/block-io.h"
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#include "trace.h"
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#include "qemu/sockets.h" /* for EINPROGRESS on Windows */
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#include "qed.h"
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#include "qemu/bswap.h"
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#include "qemu/memalign.h"
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/* Called with table_lock held.  */
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static int coroutine_fn GRAPH_RDLOCK
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qed_read_table(BDRVQEDState *s, uint64_t offset, QEDTable *table)
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{
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    unsigned int bytes = s->header.cluster_size * s->header.table_size;
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    int noffsets;
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    int i, ret;
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    trace_qed_read_table(s, offset, table);
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    qemu_co_mutex_unlock(&s->table_lock);
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    ret = bdrv_co_pread(s->bs->file, offset, bytes, table->offsets, 0);
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    qemu_co_mutex_lock(&s->table_lock);
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    if (ret < 0) {
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        goto out;
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    }
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    /* Byteswap offsets */
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    noffsets = bytes / sizeof(uint64_t);
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    for (i = 0; i < noffsets; i++) {
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        table->offsets[i] = le64_to_cpu(table->offsets[i]);
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    }
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    ret = 0;
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out:
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    /* Completion */
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    trace_qed_read_table_cb(s, table, ret);
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    return ret;
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}
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/**
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 * Write out an updated part or all of a table
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 *
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 * @s:          QED state
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 * @offset:     Offset of table in image file, in bytes
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 * @table:      Table
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 * @index:      Index of first element
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 * @n:          Number of elements
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 * @flush:      Whether or not to sync to disk
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 *
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 * Called with table_lock held.
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 */
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static int coroutine_fn GRAPH_RDLOCK
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qed_write_table(BDRVQEDState *s, uint64_t offset, QEDTable *table,
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                unsigned int index, unsigned int n, bool flush)
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{
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    unsigned int sector_mask = BDRV_SECTOR_SIZE / sizeof(uint64_t) - 1;
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    unsigned int start, end, i;
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    QEDTable *new_table;
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    size_t len_bytes;
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    int ret;
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    trace_qed_write_table(s, offset, table, index, n);
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    /* Calculate indices of the first and one after last elements */
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    start = index & ~sector_mask;
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    end = (index + n + sector_mask) & ~sector_mask;
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    len_bytes = (end - start) * sizeof(uint64_t);
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    new_table = qemu_blockalign(s->bs, len_bytes);
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    /* Byteswap table */
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    for (i = start; i < end; i++) {
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        uint64_t le_offset = cpu_to_le64(table->offsets[i]);
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        new_table->offsets[i - start] = le_offset;
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    }
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    /* Adjust for offset into table */
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    offset += start * sizeof(uint64_t);
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    qemu_co_mutex_unlock(&s->table_lock);
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    ret = bdrv_co_pwrite(s->bs->file, offset, len_bytes, new_table->offsets, 0);
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    qemu_co_mutex_lock(&s->table_lock);
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    trace_qed_write_table_cb(s, table, flush, ret);
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    if (ret < 0) {
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        goto out;
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    }
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    if (flush) {
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        ret = bdrv_co_flush(s->bs);
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        if (ret < 0) {
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            goto out;
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        }
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    }
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    ret = 0;
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out:
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    qemu_vfree(new_table);
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    return ret;
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}
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int coroutine_fn qed_read_l1_table_sync(BDRVQEDState *s)
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{
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    return qed_read_table(s, s->header.l1_table_offset, s->l1_table);
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}
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/* Called with table_lock held.  */
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int coroutine_fn qed_write_l1_table(BDRVQEDState *s, unsigned int index,
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                                    unsigned int n)
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{
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    BLKDBG_CO_EVENT(s->bs->file, BLKDBG_L1_UPDATE);
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    return qed_write_table(s, s->header.l1_table_offset,
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                           s->l1_table, index, n, false);
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}
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int coroutine_fn qed_write_l1_table_sync(BDRVQEDState *s, unsigned int index,
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                                         unsigned int n)
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{
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    return qed_write_l1_table(s, index, n);
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}
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/* Called with table_lock held.  */
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int coroutine_fn qed_read_l2_table(BDRVQEDState *s, QEDRequest *request,
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                                   uint64_t offset)
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{
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    int ret;
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    qed_unref_l2_cache_entry(request->l2_table);
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    /* Check for cached L2 entry */
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    request->l2_table = qed_find_l2_cache_entry(&s->l2_cache, offset);
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    if (request->l2_table) {
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        return 0;
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    }
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    request->l2_table = qed_alloc_l2_cache_entry(&s->l2_cache);
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    request->l2_table->table = qed_alloc_table(s);
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    BLKDBG_CO_EVENT(s->bs->file, BLKDBG_L2_LOAD);
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    ret = qed_read_table(s, offset, request->l2_table->table);
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    if (ret) {
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        /* can't trust loaded L2 table anymore */
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        qed_unref_l2_cache_entry(request->l2_table);
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        request->l2_table = NULL;
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    } else {
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        request->l2_table->offset = offset;
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        qed_commit_l2_cache_entry(&s->l2_cache, request->l2_table);
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        /* This is guaranteed to succeed because we just committed the entry
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         * to the cache.
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         */
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        request->l2_table = qed_find_l2_cache_entry(&s->l2_cache, offset);
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        assert(request->l2_table != NULL);
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    }
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    return ret;
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}
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int coroutine_fn qed_read_l2_table_sync(BDRVQEDState *s, QEDRequest *request,
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                                        uint64_t offset)
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{
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    return qed_read_l2_table(s, request, offset);
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}
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/* Called with table_lock held.  */
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int coroutine_fn qed_write_l2_table(BDRVQEDState *s, QEDRequest *request,
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                                    unsigned int index, unsigned int n,
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                                    bool flush)
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{
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    BLKDBG_CO_EVENT(s->bs->file, BLKDBG_L2_UPDATE);
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    return qed_write_table(s, request->l2_table->offset,
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                           request->l2_table->table, index, n, flush);
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}
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int coroutine_fn qed_write_l2_table_sync(BDRVQEDState *s, QEDRequest *request,
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                                         unsigned int index, unsigned int n,
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                                         bool flush)
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{
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    return qed_write_l2_table(s, request, index, n, flush);
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}
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