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From aa604fc31ecd9c11e59bc586eabea7cfa9c9175e Mon Sep 17 00:00:00 2001
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From: Max Reitz <mreitz@redhat.com>
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Date: Tue, 18 Nov 2014 15:30:16 +0100
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Subject: [PATCH 3/7] block/raw-posix: use seek_hole ahead of fiemap
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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Message-id: <1416324620-16229-4-git-send-email-mreitz@redhat.com>
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Patchwork-id: 62438
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O-Subject: [RHEL-7.1/7.0.z qemu-kvm PATCH v3 3/7] block/raw-posix: use seek_hole ahead of fiemap
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Bugzilla: 1166605
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
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RH-Acked-by: Markus Armbruster <armbru@redhat.com>
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From: Tony Breeds <tony@bakeyournoodle.com>
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try_fiemap() uses FIEMAP_FLAG_SYNC which has a significant performance
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impact.
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Prefer seek_hole() over fiemap() to avoid this impact where possible.
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seek_hole is more widely used and, arguably, has potential to be
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optimised in the kernel.
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Reported-By: Michael Steffens <michael_steffens@posteo.de>
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Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
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Cc: Kevin Wolf <kwolf@redhat.com>
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Cc: Markus Armbruster <armbru@redhat.com>
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Cc: Stefan Hajnoczi <stefanha@redhat.com>
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Cc: Max Reitz <mreitz@redhat.com>
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Cc: Pádraig Brady <pbrady@redhat.com>
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Cc: Eric Blake <eblake@redhat.com>
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Reviewed-by: Eric Blake <eblake@redhat.com>
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Reviewed-by: Max Reitz <mreitz@redhat.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit 7c15903789953ead14a417882657d52dc0c19a24)
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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block/raw-posix.c | 4 ++--
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1 file changed, 2 insertions(+), 2 deletions(-)
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diff --git a/block/raw-posix.c b/block/raw-posix.c
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index 0d963eb..47b4b71 100644
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--- a/block/raw-posix.c
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+++ b/block/raw-posix.c
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@@ -1366,9 +1366,9 @@ static int64_t coroutine_fn raw_co_get_block_status(BlockDriverState *bs,
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start = sector_num * BDRV_SECTOR_SIZE;
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- ret = try_fiemap(bs, start, &data, &hole, nb_sectors, pnum);
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+ ret = try_seek_hole(bs, start, &data, &hole, pnum);
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if (ret < 0) {
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- ret = try_seek_hole(bs, start, &data, &hole, pnum);
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+ ret = try_fiemap(bs, start, &data, &hole, nb_sectors, pnum);
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if (ret < 0) {
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/* Assume everything is allocated. */
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data = 0;
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--
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1.8.3.1
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