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From 47601d6fd4a620799984340c1fd44ff472f9d824 Mon Sep 17 00:00:00 2001
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Message-Id: <47601d6fd4a620799984340c1fd44ff472f9d824.1418766606.git.jen@redhat.com>
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In-Reply-To: <6f81b4847eb68ebdf54a8f1a771e19d112d74152.1418766606.git.jen@redhat.com>
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References: <6f81b4847eb68ebdf54a8f1a771e19d112d74152.1418766606.git.jen@redhat.com>
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From: Fam Zheng <famz@redhat.com>
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Date: Thu, 4 Dec 2014 00:05:18 -0600
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Subject: [CHANGE 24/31] block: New bdrv_nb_sectors()
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To: rhvirt-patches@redhat.com,
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    jen@redhat.com
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RH-Author: Fam Zheng <famz@redhat.com>
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Message-id: <1417651524-18041-25-git-send-email-famz@redhat.com>
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Patchwork-id: 62697
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O-Subject: [RHEL-7.1 qemu-kvm PATCH v5 24/30] block: New bdrv_nb_sectors()
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Bugzilla: 1002493
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RH-Acked-by: Jeffrey Cody <jcody@redhat.com>
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RH-Acked-by: Markus Armbruster <armbru@redhat.com>
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RH-Acked-by: Max Reitz <mreitz@redhat.com>
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From: Markus Armbruster <armbru@redhat.com>
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A call to retrieve the image size converts between bytes and sectors
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several times:
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* BlockDriver method bdrv_getlength() returns bytes.
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* refresh_total_sectors() converts to sectors, rounding up, and stores
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  in total_sectors.
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* bdrv_getlength() converts total_sectors back to bytes (now rounded
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  up to a multiple of the sector size).
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* Callers wanting sectors rather bytes convert it right back.
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  Example: bdrv_get_geometry().
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bdrv_nb_sectors() provides a way to omit the last two conversions.
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It's exactly bdrv_getlength() with the conversion to bytes omitted.
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It's functionally like bdrv_get_geometry() without its odd error
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handling.
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Reimplement bdrv_getlength() and bdrv_get_geometry() on top of
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bdrv_nb_sectors().
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The next patches will convert some users of bdrv_getlength() to
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bdrv_nb_sectors().
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Signed-off-by: Markus Armbruster <armbru@redhat.com>
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Reviewed-by: Eric Blake <eblake@redhat.com>
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Reviewed-by: Benoit Canet <benoit@irqsave.net>
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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(cherry picked from commit 65a9bb25d6b7a4bb41edb102fa0363d81800b417)
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Signed-off-by: Fam Zheng <famz@redhat.com>
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Signed-off-by: Jeff E. Nelson <jen@redhat.com>
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---
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 block.c               | 29 +++++++++++++++++++----------
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 include/block/block.h |  1 +
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 2 files changed, 20 insertions(+), 10 deletions(-)
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diff --git a/block.c b/block.c
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index d7b6376..21418a6 100644
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--- a/block.c
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+++ b/block.c
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@@ -647,6 +647,7 @@ static int find_image_format(BlockDriverState *bs, const char *filename,
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 /**
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  * Set the current 'total_sectors' value
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+ * Return 0 on success, -errno on error.
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  */
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 static int refresh_total_sectors(BlockDriverState *bs, int64_t hint)
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 {
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@@ -3255,11 +3256,12 @@ int64_t bdrv_get_allocated_file_size(BlockDriverState *bs)
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 }
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 /**
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- * Length of a file in bytes. Return < 0 if error or unknown.
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+ * Return number of sectors on success, -errno on error.
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  */
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-int64_t bdrv_getlength(BlockDriverState *bs)
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+int64_t bdrv_nb_sectors(BlockDriverState *bs)
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 {
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     BlockDriver *drv = bs->drv;
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+
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     if (!drv)
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         return -ENOMEDIUM;
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@@ -3269,19 +3271,26 @@ int64_t bdrv_getlength(BlockDriverState *bs)
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             return ret;
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         }
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     }
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-    return bs->total_sectors * BDRV_SECTOR_SIZE;
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+    return bs->total_sectors;
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+}
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+
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+/**
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+ * Return length in bytes on success, -errno on error.
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+ * The length is always a multiple of BDRV_SECTOR_SIZE.
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+ */
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+int64_t bdrv_getlength(BlockDriverState *bs)
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+{
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+    int64_t ret = bdrv_nb_sectors(bs);
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+
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+    return ret < 0 ? ret : ret * BDRV_SECTOR_SIZE;
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 }
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 /* return 0 as number of sectors if no device present or error */
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 void bdrv_get_geometry(BlockDriverState *bs, uint64_t *nb_sectors_ptr)
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 {
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-    int64_t length;
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-    length = bdrv_getlength(bs);
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-    if (length < 0)
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-        length = 0;
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-    else
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-        length = length >> BDRV_SECTOR_BITS;
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-    *nb_sectors_ptr = length;
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+    int64_t nb_sectors = bdrv_nb_sectors(bs);
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+
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+    *nb_sectors_ptr = nb_sectors < 0 ? 0 : nb_sectors;
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 }
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 /* throttling disk io limits */
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diff --git a/include/block/block.h b/include/block/block.h
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index b06a9dc..c79a1e1 100644
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--- a/include/block/block.h
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+++ b/include/block/block.h
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@@ -250,6 +250,7 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
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     const char *backing_file);
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 int bdrv_get_backing_file_depth(BlockDriverState *bs);
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 int bdrv_truncate(BlockDriverState *bs, int64_t offset);
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+int64_t bdrv_nb_sectors(BlockDriverState *bs);
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 int64_t bdrv_getlength(BlockDriverState *bs);
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 int64_t bdrv_get_allocated_file_size(BlockDriverState *bs);
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 void bdrv_get_geometry(BlockDriverState *bs, uint64_t *nb_sectors_ptr);
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-- 
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2.1.0
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