Blame SOURCES/kvm-qcow2-Repair-OFLAG_COPIED-when-fixing-leaks.patch

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From ec8057f43c44075e02b59078b38b40340220f955 Mon Sep 17 00:00:00 2001
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From: Max Reitz <mreitz@redhat.com>
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Date: Mon, 18 Jun 2018 17:24:53 +0200
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Subject: [PATCH 05/17] qcow2: Repair OFLAG_COPIED when fixing leaks
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RH-Author: Max Reitz <mreitz@redhat.com>
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Message-id: <20180618172454.27434-2-mreitz@redhat.com>
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Patchwork-id: 80785
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O-Subject: [RHEL-7.6 qemu-kvm PATCH 1/2] qcow2: Repair OFLAG_COPIED when fixing leaks
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Bugzilla: 1527122
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RH-Acked-by: John Snow <jsnow@redhat.com>
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RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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Repairing OFLAG_COPIED is usually safe because it is done after the
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refcounts have been repaired.  Therefore, it we did not find anyone else
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referencing a data or L2 cluster, it makes no sense to not set
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OFLAG_COPIED -- and the other direction (clearing OFLAG_COPIED) is
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always safe, anyway, it may just induce leaks.
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Furthermore, if OFLAG_COPIED is actually consistent with a wrong (leaky)
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refcount, we will decrement the refcount with -r leaks, but OFLAG_COPIED
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will then be wrong.  qemu-img check should not produce images that are
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more corrupted afterwards then they were before.
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Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1527085
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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Reviewed-by: Eric Blake <eblake@redhat.com>
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Message-id: 20180509200059.31125-2-mreitz@redhat.com
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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(cherry picked from commit 3cce51c919c7b4028cf6676dfcb80a45741b5117)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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Conflicts:
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	block/qcow2-refcount.c
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Conflicts due to refcounts being fixed to 16 bit downstream, which means
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that every instance of the "refcount" variable is an int instead of
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uint64_t.  This results in contextual conflicts in the corruption
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printf()s.
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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---
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 block/qcow2-refcount.c | 25 +++++++++++++++++--------
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 1 file changed, 17 insertions(+), 8 deletions(-)
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diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
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index 848fd31..7a69bcd 100644
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--- a/block/qcow2-refcount.c
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+++ b/block/qcow2-refcount.c
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@@ -1333,6 +1333,19 @@ static int check_oflag_copied(BlockDriverState *bs, BdrvCheckResult *res,
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     int ret;
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     int refcount;
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     int i, j;
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+    bool repair;
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+
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+    if (fix & BDRV_FIX_ERRORS) {
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+        /* Always repair */
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+        repair = true;
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+    } else if (fix & BDRV_FIX_LEAKS) {
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+        /* Repair only if that seems safe: This function is always
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+         * called after the refcounts have been fixed, so the refcount
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+         * is accurate if that repair was successful */
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+        repair = !res->check_errors && !res->corruptions && !res->leaks;
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+    } else {
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+        repair = false;
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+    }
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     for (i = 0; i < s->l1_size; i++) {
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         uint64_t l1_entry = s->l1_table[i];
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@@ -1351,10 +1364,8 @@ static int check_oflag_copied(BlockDriverState *bs, BdrvCheckResult *res,
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         if ((refcount == 1) != ((l1_entry & QCOW_OFLAG_COPIED) != 0)) {
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             fprintf(stderr, "%s OFLAG_COPIED L2 cluster: l1_index=%d "
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                     "l1_entry=%" PRIx64 " refcount=%d\n",
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-                    fix & BDRV_FIX_ERRORS ? "Repairing" :
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-                                            "ERROR",
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-                    i, l1_entry, refcount);
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-            if (fix & BDRV_FIX_ERRORS) {
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+                    repair ? "Repairing" : "ERROR", i, l1_entry, refcount);
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+            if (repair) {
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                 s->l1_table[i] = refcount == 1
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                                ? l1_entry |  QCOW_OFLAG_COPIED
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                                : l1_entry & ~QCOW_OFLAG_COPIED;
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@@ -1393,10 +1404,8 @@ static int check_oflag_copied(BlockDriverState *bs, BdrvCheckResult *res,
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                 if ((refcount == 1) != ((l2_entry & QCOW_OFLAG_COPIED) != 0)) {
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                     fprintf(stderr, "%s OFLAG_COPIED data cluster: "
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                             "l2_entry=%" PRIx64 " refcount=%d\n",
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-                            fix & BDRV_FIX_ERRORS ? "Repairing" :
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-                                                    "ERROR",
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-                            l2_entry, refcount);
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-                    if (fix & BDRV_FIX_ERRORS) {
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+                            repair ? "Repairing" : "ERROR", l2_entry, refcount);
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+                    if (repair) {
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                         l2_table[j] = cpu_to_be64(refcount == 1
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                                     ? l2_entry |  QCOW_OFLAG_COPIED
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                                     : l2_entry & ~QCOW_OFLAG_COPIED);
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-- 
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1.8.3.1
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