qemu

block.c (7305B)

---

 /*
  * Common code for block device models
  *
  * Copyright (C) 2012 Red Hat, Inc.
  *
  * This work is licensed under the terms of the GNU GPL, version 2 or
  * later.  See the COPYING file in the top-level directory.
  */
 
 #include "qemu/osdep.h"
 #include "sysemu/blockdev.h"
 #include "sysemu/block-backend.h"
 #include "hw/block/block.h"
 #include "qapi/error.h"
 #include "qapi/qapi-types-block.h"
 
 /*
  * Read the entire contents of @blk into @buf.
  * @blk's contents must be @size bytes, and @size must be at most
  * BDRV_REQUEST_MAX_BYTES.
  * On success, return true.
  * On failure, store an error through @errp and return false.
  * Note that the error messages do not identify the block backend.
  * TODO Since callers don't either, this can result in confusing
  * errors.
  * This function not intended for actual block devices, which read on
  * demand.  It's for things like memory devices that (ab)use a block
  * backend to provide persistence.
  */
 bool blk_check_size_and_read_all(BlockBackend *blk, void *buf, hwaddr size,
                                  Error **errp)
 {
     int64_t blk_len;
     int ret;
 
     blk_len = blk_getlength(blk);
     if (blk_len < 0) {
         error_setg_errno(errp, -blk_len,
                          "can't get size of block backend");
         return false;
     }
     if (blk_len != size) {
         error_setg(errp, "device requires %" HWADDR_PRIu " bytes, "
                    "block backend provides %" PRIu64 " bytes",
                    size, blk_len);
         return false;
     }
 
     /*
      * We could loop for @size > BDRV_REQUEST_MAX_BYTES, but if we
      * ever get to the point we want to read *gigabytes* here, we
      * should probably rework the device to be more like an actual
      * block device and read only on demand.
      */
     assert(size <= BDRV_REQUEST_MAX_BYTES);
     ret = blk_pread(blk, 0, size, buf, 0);
     if (ret < 0) {
         error_setg_errno(errp, -ret, "can't read block backend");
         return false;
     }
     return true;
 }
 
 bool blkconf_blocksizes(BlockConf *conf, Error **errp)
 {
     BlockBackend *blk = conf->blk;
     BlockSizes blocksizes;
     BlockDriverState *bs;
     bool use_blocksizes;
     bool use_bs;
 
     switch (conf->backend_defaults) {
     case ON_OFF_AUTO_AUTO:
         use_blocksizes = !blk_probe_blocksizes(blk, &blocksizes);
         use_bs = false;
         break;
 
     case ON_OFF_AUTO_ON:
         use_blocksizes = !blk_probe_blocksizes(blk, &blocksizes);
         bs = blk_bs(blk);
         use_bs = bs;
         break;
 
     case ON_OFF_AUTO_OFF:
         use_blocksizes = false;
         use_bs = false;
         break;
 
     default:
         abort();
     }
 
     /* fill in detected values if they are not defined via qemu command line */
     if (!conf->physical_block_size) {
         if (use_blocksizes) {
            conf->physical_block_size = blocksizes.phys;
         } else {
             conf->physical_block_size = BDRV_SECTOR_SIZE;
         }
     }
     if (!conf->logical_block_size) {
         if (use_blocksizes) {
             conf->logical_block_size = blocksizes.log;
         } else {
             conf->logical_block_size = BDRV_SECTOR_SIZE;
         }
     }
     if (use_bs) {
         if (!conf->opt_io_size) {
             conf->opt_io_size = bs->bl.opt_transfer;
         }
         if (conf->discard_granularity == -1) {
             if (bs->bl.pdiscard_alignment) {
                 conf->discard_granularity = bs->bl.pdiscard_alignment;
             } else if (bs->bl.request_alignment != 1) {
                 conf->discard_granularity = bs->bl.request_alignment;
             }
         }
     }
 
     if (conf->logical_block_size > conf->physical_block_size) {
         error_setg(errp,
                    "logical_block_size > physical_block_size not supported");
         return false;
     }
 
     if (!QEMU_IS_ALIGNED(conf->min_io_size, conf->logical_block_size)) {
         error_setg(errp,
                    "min_io_size must be a multiple of logical_block_size");
         return false;
     }
 
     /*
      * all devices which support min_io_size (scsi and virtio-blk) expose it to
      * the guest as a uint16_t in units of logical blocks
      */
     if (conf->min_io_size / conf->logical_block_size > UINT16_MAX) {
         error_setg(errp, "min_io_size must not exceed %u logical blocks",
                    UINT16_MAX);
         return false;
     }
 
     if (!QEMU_IS_ALIGNED(conf->opt_io_size, conf->logical_block_size)) {
         error_setg(errp,
                    "opt_io_size must be a multiple of logical_block_size");
         return false;
     }
 
     if (conf->discard_granularity != -1 &&
         !QEMU_IS_ALIGNED(conf->discard_granularity,
                          conf->logical_block_size)) {
         error_setg(errp, "discard_granularity must be "
                    "a multiple of logical_block_size");
         return false;
     }
 
     return true;
 }
 
 bool blkconf_apply_backend_options(BlockConf *conf, bool readonly,
                                    bool resizable, Error **errp)
 {
     BlockBackend *blk = conf->blk;
     BlockdevOnError rerror, werror;
     uint64_t perm, shared_perm;
     bool wce;
     int ret;
 
     perm = BLK_PERM_CONSISTENT_READ;
     if (!readonly) {
         perm |= BLK_PERM_WRITE;
     }
 
     shared_perm = BLK_PERM_CONSISTENT_READ | BLK_PERM_WRITE_UNCHANGED;
     if (resizable) {
         shared_perm |= BLK_PERM_RESIZE;
     }
     if (conf->share_rw) {
         shared_perm |= BLK_PERM_WRITE;
     }
 
     ret = blk_set_perm(blk, perm, shared_perm, errp);
     if (ret < 0) {
         return false;
     }
 
     switch (conf->wce) {
     case ON_OFF_AUTO_ON:    wce = true; break;
     case ON_OFF_AUTO_OFF:   wce = false; break;
     case ON_OFF_AUTO_AUTO:  wce = blk_enable_write_cache(blk); break;
     default:
         abort();
     }
 
     rerror = conf->rerror;
     if (rerror == BLOCKDEV_ON_ERROR_AUTO) {
         rerror = blk_get_on_error(blk, true);
     }
 
     werror = conf->werror;
     if (werror == BLOCKDEV_ON_ERROR_AUTO) {
         werror = blk_get_on_error(blk, false);
     }
 
     blk_set_enable_write_cache(blk, wce);
     blk_set_on_error(blk, rerror, werror);
 
     block_acct_setup(blk_get_stats(blk), conf->account_invalid,
                      conf->account_failed);
     return true;
 }
 
 bool blkconf_geometry(BlockConf *conf, int *ptrans,
                       unsigned cyls_max, unsigned heads_max, unsigned secs_max,
                       Error **errp)
 {
     if (!conf->cyls && !conf->heads && !conf->secs) {
         hd_geometry_guess(conf->blk,
                           &conf->cyls, &conf->heads, &conf->secs,
                           ptrans);
     } else if (ptrans && *ptrans == BIOS_ATA_TRANSLATION_AUTO) {
         *ptrans = hd_bios_chs_auto_trans(conf->cyls, conf->heads, conf->secs);
     }
     if (conf->cyls || conf->heads || conf->secs) {
         if (conf->cyls < 1 || conf->cyls > cyls_max) {
             error_setg(errp, "cyls must be between 1 and %u", cyls_max);
             return false;
         }
         if (conf->heads < 1 || conf->heads > heads_max) {
             error_setg(errp, "heads must be between 1 and %u", heads_max);
             return false;
         }
         if (conf->secs < 1 || conf->secs > secs_max) {
             error_setg(errp, "secs must be between 1 and %u", secs_max);
             return false;
         }
     }
     return true;
 }