65 lines
2.3 KiB
Diff
65 lines
2.3 KiB
Diff
From 39e0c370357a414abacd64fb6a172e7b25eb4d82 Mon Sep 17 00:00:00 2001
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From: Eric Blake <eblake@redhat.com>
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Date: Fri, 9 May 2025 15:40:19 -0500
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Subject: [PATCH 04/16] file-posix, gluster: Handle zero block status hint
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better
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RH-Author: Eric Blake <eblake@redhat.com>
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RH-MergeRequest: 365: blockdev-mirror: More efficient handling of sparse mirrors
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RH-Jira: RHEL-82906 RHEL-83015
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Jon Maloy <jmaloy@redhat.com>
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RH-Commit: [2/14] 1f7b47ce5f5fb321aee41a16accf5bce3d1bfe95 (ebblake/centos-qemu-kvm)
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Although the previous patch to change 'bool want_zero' into a bitmask
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made no semantic change, it is now time to differentiate. When the
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caller specifically wants to know what parts of the file read as zero,
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we need to use lseek and actually reporting holes, rather than
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short-circuiting and advertising full allocation.
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This change will be utilized in later patches to let mirroring
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optimize for the case when the destination already reads as zeroes.
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Signed-off-by: Eric Blake <eblake@redhat.com>
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Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
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Message-ID: <20250509204341.3553601-17-eblake@redhat.com>
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(cherry picked from commit a6a0a7fb0e327d17594c971b4a39de14e025b415)
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Jira: https://issues.redhat.com/browse/RHEL-82906
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Jira: https://issues.redhat.com/browse/RHEL-83015
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Signed-off-by: Eric Blake <eblake@redhat.com>
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---
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block/file-posix.c | 3 ++-
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block/gluster.c | 2 +-
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2 files changed, 3 insertions(+), 2 deletions(-)
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diff --git a/block/file-posix.c b/block/file-posix.c
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index 9ca55620ca..ce5da2b4c2 100644
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--- a/block/file-posix.c
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+++ b/block/file-posix.c
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@@ -3293,7 +3293,8 @@ static int coroutine_fn raw_co_block_status(BlockDriverState *bs,
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return ret;
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}
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- if (mode != BDRV_WANT_PRECISE) {
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+ if (!(mode & BDRV_WANT_ZERO)) {
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+ /* There is no backing file - all bytes are allocated in this file. */
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*pnum = bytes;
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*map = offset;
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*file = bs;
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diff --git a/block/gluster.c b/block/gluster.c
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index ae5c45666b..175c70164c 100644
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--- a/block/gluster.c
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+++ b/block/gluster.c
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@@ -1483,7 +1483,7 @@ static int coroutine_fn qemu_gluster_co_block_status(BlockDriverState *bs,
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return ret;
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}
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- if (mode != BDRV_WANT_PRECISE) {
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+ if (!(mode & BDRV_WANT_ZERO)) {
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*pnum = bytes;
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*map = offset;
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*file = bs;
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--
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2.48.1
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