From d4803ddf6139cf2ad7e2d53035b5f828da97b51c Mon Sep 17 00:00:00 2001
From: Max Reitz <mreitz@redhat.com>
Date: Mon, 4 Nov 2013 22:32:04 +0100
Subject: [PATCH 11/87] qcow2-refcount: Repair shared refcount blocks
RH-Author: Max Reitz <mreitz@redhat.com>
Message-id: <1383604354-12743-14-git-send-email-mreitz@redhat.com>
Patchwork-id: 55313
O-Subject: [RHEL-7.0 qemu-kvm PATCH 13/43] qcow2-refcount: Repair shared refcount blocks
Bugzilla: 1004347
RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
RH-Acked-by: Fam Zheng <famz@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
BZ: 1004347
If the refcount of a refcount block is greater than one, we can at least
try to repair that problem by duplicating the affected block.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit afa50193cde574528a130a25544fd6f3aa8da069)
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
block/blkdebug.c | 1 +
block/qcow2-refcount.c | 148 ++++++++++++++++++++++++++++++++++++++++++++++++-
include/block/block.h | 1 +
3 files changed, 148 insertions(+), 2 deletions(-)
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
block/blkdebug.c | 1 +
block/qcow2-refcount.c | 148 +++++++++++++++++++++++++++++++++++++++++++++++-
include/block/block.h | 1 +
3 files changed, 148 insertions(+), 2 deletions(-)
diff --git a/block/blkdebug.c b/block/blkdebug.c
index 71f99e4..d659d38 100644
--- a/block/blkdebug.c
+++ b/block/blkdebug.c
@@ -168,6 +168,7 @@ static const char *event_names[BLKDBG_EVENT_MAX] = {
[BLKDBG_REFTABLE_LOAD] = "reftable_load",
[BLKDBG_REFTABLE_GROW] = "reftable_grow",
+ [BLKDBG_REFTABLE_UPDATE] = "reftable_update",
[BLKDBG_REFBLOCK_LOAD] = "refblock_load",
[BLKDBG_REFBLOCK_UPDATE] = "refblock_update",
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 92ecc64..927bdeb 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -1320,6 +1320,121 @@ fail:
}
/*
+ * Writes one sector of the refcount table to the disk
+ */
+#define RT_ENTRIES_PER_SECTOR (512 / sizeof(uint64_t))
+static int write_reftable_entry(BlockDriverState *bs, int rt_index)
+{
+ BDRVQcowState *s = bs->opaque;
+ uint64_t buf[RT_ENTRIES_PER_SECTOR];
+ int rt_start_index;
+ int i, ret;
+
+ rt_start_index = rt_index & ~(RT_ENTRIES_PER_SECTOR - 1);
+ for (i = 0; i < RT_ENTRIES_PER_SECTOR; i++) {
+ buf[i] = cpu_to_be64(s->refcount_table[rt_start_index + i]);
+ }
+
+ ret = qcow2_pre_write_overlap_check(bs,
+ QCOW2_OL_DEFAULT & ~QCOW2_OL_REFCOUNT_TABLE,
+ s->refcount_table_offset + rt_start_index * sizeof(uint64_t),
+ sizeof(buf));
+ if (ret < 0) {
+ return ret;
+ }
+
+ BLKDBG_EVENT(bs->file, BLKDBG_REFTABLE_UPDATE);
+ ret = bdrv_pwrite_sync(bs->file, s->refcount_table_offset +
+ rt_start_index * sizeof(uint64_t), buf, sizeof(buf));
+ if (ret < 0) {
+ return ret;
+ }
+
+ return 0;
+}
+
+/*
+ * Allocates a new cluster for the given refcount block (represented by its
+ * offset in the image file) and copies the current content there. This function
+ * does _not_ decrement the reference count for the currently occupied cluster.
+ *
+ * This function prints an informative message to stderr on error (and returns
+ * -errno); on success, 0 is returned.
+ */
+static int64_t realloc_refcount_block(BlockDriverState *bs, int reftable_index,
+ uint64_t offset)
+{
+ BDRVQcowState *s = bs->opaque;
+ int64_t new_offset = 0;
+ void *refcount_block = NULL;
+ int ret;
+
+ /* allocate new refcount block */
+ new_offset = qcow2_alloc_clusters(bs, s->cluster_size);
+ if (new_offset < 0) {
+ fprintf(stderr, "Could not allocate new cluster: %s\n",
+ strerror(-new_offset));
+ ret = new_offset;
+ goto fail;
+ }
+
+ /* fetch current refcount block content */
+ ret = qcow2_cache_get(bs, s->refcount_block_cache, offset, &refcount_block);
+ if (ret < 0) {
+ fprintf(stderr, "Could not fetch refcount block: %s\n", strerror(-ret));
+ goto fail;
+ }
+
+ /* new block has not yet been entered into refcount table, therefore it is
+ * no refcount block yet (regarding this check) */
+ ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_DEFAULT, new_offset,
+ s->cluster_size);
+ if (ret < 0) {
+ fprintf(stderr, "Could not write refcount block; metadata overlap "
+ "check failed: %s\n", strerror(-ret));
+ /* the image will be marked corrupt, so don't even attempt on freeing
+ * the cluster */
+ new_offset = 0;
+ goto fail;
+ }
+
+ /* write to new block */
+ ret = bdrv_write(bs->file, new_offset / BDRV_SECTOR_SIZE, refcount_block,
+ s->cluster_sectors);
+ if (ret < 0) {
+ fprintf(stderr, "Could not write refcount block: %s\n", strerror(-ret));
+ goto fail;
+ }
+
+ /* update refcount table */
+ assert(!(new_offset & (s->cluster_size - 1)));
+ s->refcount_table[reftable_index] = new_offset;
+ ret = write_reftable_entry(bs, reftable_index);
+ if (ret < 0) {
+ fprintf(stderr, "Could not update refcount table: %s\n",
+ strerror(-ret));
+ goto fail;
+ }
+
+fail:
+ if (new_offset && (ret < 0)) {
+ qcow2_free_clusters(bs, new_offset, s->cluster_size,
+ QCOW2_DISCARD_ALWAYS);
+ }
+ if (refcount_block) {
+ if (ret < 0) {
+ qcow2_cache_put(bs, s->refcount_block_cache, &refcount_block);
+ } else {
+ ret = qcow2_cache_put(bs, s->refcount_block_cache, &refcount_block);
+ }
+ }
+ if (ret < 0) {
+ return ret;
+ }
+ return new_offset;
+}
+
+/*
* Checks an image for refcount consistency.
*
* Returns 0 if no errors are found, the number of errors in case the image is
@@ -1395,10 +1510,39 @@ int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
inc_refcounts(bs, res, refcount_table, nb_clusters,
offset, s->cluster_size);
if (refcount_table[cluster] != 1) {
- fprintf(stderr, "ERROR refcount block %" PRId64
+ fprintf(stderr, "%s refcount block %" PRId64
" refcount=%d\n",
+ fix & BDRV_FIX_ERRORS ? "Repairing" :
+ "ERROR",
i, refcount_table[cluster]);
- res->corruptions++;
+
+ if (fix & BDRV_FIX_ERRORS) {
+ int64_t new_offset;
+
+ new_offset = realloc_refcount_block(bs, i, offset);
+ if (new_offset < 0) {
+ res->corruptions++;
+ continue;
+ }
+
+ /* update refcounts */
+ if ((new_offset >> s->cluster_bits) >= nb_clusters) {
+ /* increase refcount_table size if necessary */
+ int old_nb_clusters = nb_clusters;
+ nb_clusters = (new_offset >> s->cluster_bits) + 1;
+ refcount_table = g_realloc(refcount_table,
+ nb_clusters * sizeof(uint16_t));
+ memset(&refcount_table[old_nb_clusters], 0, (nb_clusters
+ - old_nb_clusters) * sizeof(uint16_t));
+ }
+ refcount_table[cluster]--;
+ inc_refcounts(bs, res, refcount_table, nb_clusters,
+ new_offset, s->cluster_size);
+
+ res->corruptions_fixed++;
+ } else {
+ res->corruptions++;
+ }
}
}
}
diff --git a/include/block/block.h b/include/block/block.h
index 03ebc47..39770a3 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -447,6 +447,7 @@ typedef enum {
BLKDBG_REFTABLE_LOAD,
BLKDBG_REFTABLE_GROW,
+ BLKDBG_REFTABLE_UPDATE,
BLKDBG_REFBLOCK_LOAD,
BLKDBG_REFBLOCK_UPDATE,
--
1.7.1