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From 69fe324e32aad7e1afc6ad14021a6a08ad52646c Mon Sep 17 00:00:00 2001
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From: Max Reitz <mreitz@redhat.com>
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Date: Sat, 13 Jun 2015 16:22:27 +0200
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Subject: [PATCH 33/42] block: Respect underlying file's EOF
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Message-id: <1434212556-3927-34-git-send-email-mreitz@redhat.com>
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Patchwork-id: 66052
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O-Subject: [RHEL-7.2 qemu-kvm PATCH 33/42] block: Respect underlying file's EOF
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Bugzilla: 1129893
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RH-Acked-by: Jeffrey Cody <jcody@redhat.com>
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RH-Acked-by: Fam Zheng <famz@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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BZ: 1129893
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When falling through to the underlying file in
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bdrv_co_get_block_status(), if it returns that the query offset is
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beyond the file end (by setting *pnum to 0), return the range to be
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zero and do not let the number of sectors for which information could be
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obtained be overwritten.
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Signed-off-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 59c9a95fd29cfb3296ee58e8a446df251d14a459)
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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.c | 15 +++++++++++++--
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1 file changed, 13 insertions(+), 2 deletions(-)
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diff --git a/block.c b/block.c
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index 22ab762..fa6e192 100644
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--- a/block.c
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+++ b/block.c
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@@ -3797,13 +3797,24 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
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if (bs->file &&
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(ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO) &&
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(ret & BDRV_BLOCK_OFFSET_VALID)) {
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+ int file_pnum;
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+
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ret2 = bdrv_co_get_block_status(bs->file, ret >> BDRV_SECTOR_BITS,
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- *pnum, pnum);
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+ *pnum, &file_pnum);
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if (ret2 >= 0) {
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/* Ignore errors. This is just providing extra information, it
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* is useful but not necessary.
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*/
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- ret |= (ret2 & BDRV_BLOCK_ZERO);
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+ if (!file_pnum) {
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+ /* !file_pnum indicates an offset at or beyond the EOF; it is
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+ * perfectly valid for the format block driver to point to such
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+ * offsets, so catch it and mark everything as zero */
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+ ret |= BDRV_BLOCK_ZERO;
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+ } else {
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+ /* Limit request to the range reported by the protocol driver */
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+ *pnum = file_pnum;
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+ ret |= (ret2 & BDRV_BLOCK_ZERO);
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+ }
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}
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}
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--
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1.8.3.1
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