Split entry repairing to separate function, to be reused later.

Note: entry in in-memory l2 table (local variable in
check_refcounts_l2) is not updated after this patch.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block/qcow2-refcount.c | 147 ++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 109 insertions(+), 38 deletions(-)

diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 3b057b635d..d9c8cd666b 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -1554,6 +1554,99 @@ enum {
     CHECK_FRAG_INFO = 0x2,      /* update BlockFragInfo counters */
 };
 
+/* Update entry in L1 or L2 table
+ *
+ * Returns: -errno if overlap check failed
+ *          0 if write failed
+ *          1 on success
+ */
+static int write_table_entry(BlockDriverState *bs, const char *table_name,
+                             uint64_t table_offset, int entry_index,
+                             uint64_t new_val, int ign)
+{
+    int ret;
+    uint64_t entry_offset =
+            table_offset + (uint64_t)entry_index * sizeof(new_val);
+
+    cpu_to_be64s(&new_val);
+    ret = qcow2_pre_write_overlap_check(bs, ign, entry_offset, sizeof(new_val));
+    if (ret < 0) {
+        fprintf(stderr,
+                "ERROR: Can't write %s table entry: overlap check failed: %s\n",
+                table_name, strerror(-ret));
+        return ret;
+    }
+
+    ret = bdrv_pwrite_sync(bs->file, entry_offset, &new_val, sizeof(new_val));
+    if (ret < 0) {
+        fprintf(stderr, "ERROR: Failed to overwrite %s table entry: %s\n",
+                table_name, strerror(-ret));
+        return 0;
+    }
+
+    return 1;
+}
+
+/* Try to fix (if allowed) entry in L1 or L2 table. Update @res correspondingly.
+ *
+ * Returns: -errno if overlap check failed
+ *          0 if entry was not updated for other reason
+ *            (fixing disabled or write failed)
+ *          1 on success
+ */
+static int fix_table_entry(BlockDriverState *bs, BdrvCheckResult *res,
+                           BdrvCheckMode fix, const char *table_name,
+                           uint64_t table_offset, int entry_index,
+                           uint64_t new_val, int ign,
+                           const char *fmt, va_list args)
+{
+    int ret;
+
+    fprintf(stderr, fix & BDRV_FIX_ERRORS ? "Repairing: " : "ERROR: ");
+    vfprintf(stderr, fmt, args);
+    fprintf(stderr, "\n");
+
+    if (!(fix & BDRV_FIX_ERRORS)) {
+        res->corruptions++;
+        return 0;
+    }
+
+    ret = write_table_entry(bs, table_name, table_offset, entry_index, new_val,
+                            ign);
+
+    if (ret == 1) {
+        res->corruptions_fixed++;
+    } else {
+        res->check_errors++;
+    }
+
+    return ret;
+}
+
+/* Make L2 entry to be QCOW2_CLUSTER_ZERO_PLAIN
+ *
+ * Returns: -errno if overlap check failed
+ *          0 if write failed
+ *          1 on success
+ */
+static int fix_l2_entry_to_zero(BlockDriverState *bs, BdrvCheckResult *res,
+                                BdrvCheckMode fix, int64_t l2_offset,
+                                int l2_index, bool active,
+                                const char *fmt, ...)
+{
+    int ret;
+    int ign = active ? QCOW2_OL_ACTIVE_L2 : QCOW2_OL_INACTIVE_L2;
+    uint64_t l2_entry = QCOW_OFLAG_ZERO;
+    va_list args;
+
+    va_start(args, fmt);
+    ret = fix_table_entry(bs, res, fix, "L2", l2_offset, l2_index, l2_entry,
+                          ign, fmt, args);
+    va_end(args);
+
+    return ret;
+}
+
 /*
  * Increases the refcount in the given refcount table for the all clusters
  * referenced in the L2 table. While doing so, performs some checks on L2
@@ -1646,46 +1739,24 @@ static int check_refcounts_l2(BlockDriverState *bs, BdrvCheckResult *res,
                 if (qcow2_get_cluster_type(l2_entry) ==
                     QCOW2_CLUSTER_ZERO_ALLOC)
                 {
-                    fprintf(stderr, "%s offset=%" PRIx64 ": Preallocated zero "
-                            "cluster is not properly aligned; L2 entry "
-                            "corrupted.\n",
-                            fix & BDRV_FIX_ERRORS ? "Repairing" : "ERROR",
+                    ret = fix_l2_entry_to_zero(
+                            bs, res, fix, l2_offset, i, active,
+                            "offset=%" PRIx64 ": Preallocated zero cluster is "
+                            "not properly aligned; L2 entry corrupted.",
                             offset);
-                    if (fix & BDRV_FIX_ERRORS) {
-                        uint64_t l2e_offset =
-                            l2_offset + (uint64_t)i * sizeof(uint64_t);
-                        int ign = active ? QCOW2_OL_ACTIVE_L2 :
-                                           QCOW2_OL_INACTIVE_L2;
-
-                        l2_entry = QCOW_OFLAG_ZERO;
-                        l2_table[i] = cpu_to_be64(l2_entry);
-                        ret = qcow2_pre_write_overlap_check(bs, ign,
-                                l2e_offset, sizeof(uint64_t));
-                        if (ret < 0) {
-                            fprintf(stderr, "ERROR: Overlap check failed\n");
-                            res->check_errors++;
-                            /* Something is seriously wrong, so abort checking
-                             * this L2 table */
-                            goto fail;
-                        }
-
-                        ret = bdrv_pwrite_sync(bs->file, l2e_offset,
-                                               &l2_table[i], sizeof(uint64_t));
-                        if (ret < 0) {
-                            fprintf(stderr, "ERROR: Failed to overwrite L2 "
-                                    "table entry: %s\n", strerror(-ret));
-                            res->check_errors++;
-                            /* Do not abort, continue checking the rest of this
-                             * L2 table's entries */
-                        } else {
-                            res->corruptions_fixed++;
-                            /* Skip marking the cluster as used
-                             * (it is unused now) */
-                            continue;
-                        }
-                    } else {
-                        res->corruptions++;
+                    if (ret < 0) {
+                        /* Something is seriously wrong, so abort checking
+                         * this L2 table */
+                        goto fail;
+                    }
+                    if (ret == 1) {
+                        /* Skip marking the cluster as used
+                         * (it is unused now) */
+                        continue;
                     }
+                    /* Entry was not updated, but do not abort, mark cluster
+                     * as used and continue checking the rest of this L2
+                     * table's entries */
                 } else {
                     fprintf(stderr, "ERROR offset=%" PRIx64 ": Data cluster is "
                         "not properly aligned; L2 entry corrupted.\n", offset);
-- 
2.11.1

On 17.08.18 14:22, Vladimir Sementsov-Ogievskiy wrote:
> Split entry repairing to separate function, to be reused later.
> 
> Note: entry in in-memory l2 table (local variable in
> check_refcounts_l2) is not updated after this patch.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
>  block/qcow2-refcount.c | 147 ++++++++++++++++++++++++++++++++++++-------------
>  1 file changed, 109 insertions(+), 38 deletions(-)
> 
> diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
> index 3b057b635d..d9c8cd666b 100644
> --- a/block/qcow2-refcount.c
> +++ b/block/qcow2-refcount.c
> @@ -1554,6 +1554,99 @@ enum {
>      CHECK_FRAG_INFO = 0x2,      /* update BlockFragInfo counters */
>  };
>  
> +/* Update entry in L1 or L2 table
> + *
> + * Returns: -errno if overlap check failed
> + *          0 if write failed
> + *          1 on success
> + */
> +static int write_table_entry(BlockDriverState *bs, const char *table_name,
> +                             uint64_t table_offset, int entry_index,
> +                             uint64_t new_val, int ign)
> +{
> +    int ret;
> +    uint64_t entry_offset =
> +            table_offset + (uint64_t)entry_index * sizeof(new_val);
> +
> +    cpu_to_be64s(&new_val);
> +    ret = qcow2_pre_write_overlap_check(bs, ign, entry_offset, sizeof(new_val));
> +    if (ret < 0) {
> +        fprintf(stderr,
> +                "ERROR: Can't write %s table entry: overlap check failed: %s\n",

I recently complained to Berto that I don't like elisions ("can't") in
user interfaces, so I suppose I'll have to complain here, too, that I'd
prefer a "Cannot".

> +                table_name, strerror(-ret));
> +        return ret;
> +    }
> +
> +    ret = bdrv_pwrite_sync(bs->file, entry_offset, &new_val, sizeof(new_val));
> +    if (ret < 0) {
> +        fprintf(stderr, "ERROR: Failed to overwrite %s table entry: %s\n",
> +                table_name, strerror(-ret));
> +        return 0;
> +    }
> +
> +    return 1;
> +}
> +
> +/* Try to fix (if allowed) entry in L1 or L2 table. Update @res correspondingly.
> + *
> + * Returns: -errno if overlap check failed
> + *          0 if entry was not updated for other reason
> + *            (fixing disabled or write failed)
> + *          1 on success
> + */
> +static int fix_table_entry(BlockDriverState *bs, BdrvCheckResult *res,
> +                           BdrvCheckMode fix, const char *table_name,
> +                           uint64_t table_offset, int entry_index,
> +                           uint64_t new_val, int ign,
> +                           const char *fmt, va_list args)
> +{
> +    int ret;
> +
> +    fprintf(stderr, fix & BDRV_FIX_ERRORS ? "Repairing: " : "ERROR: ");
> +    vfprintf(stderr, fmt, args);
> +    fprintf(stderr, "\n");

If you're just going to print this here, right at the start, I think it
would be better to just do it in the caller.

Sure, with this solution the caller safes an fprintf() call, but I find
it a bit over the top to start with vararg handling here when the caller
can just do an additional fprintf().

(Also, I actually find it clearer if you have to call two separate
functions.)

> +
> +    if (!(fix & BDRV_FIX_ERRORS)) {
> +        res->corruptions++;
> +        return 0;
> +    }
> +
> +    ret = write_table_entry(bs, table_name, table_offset, entry_index, new_val,
> +                            ign);
> +
> +    if (ret == 1) {
> +        res->corruptions_fixed++;
> +    } else {
> +        res->check_errors++;
> +    }
> +
> +    return ret;
> +}
> +
> +/* Make L2 entry to be QCOW2_CLUSTER_ZERO_PLAIN
> + *
> + * Returns: -errno if overlap check failed
> + *          0 if write failed
> + *          1 on success
> + */
> +static int fix_l2_entry_to_zero(BlockDriverState *bs, BdrvCheckResult *res,
> +                                BdrvCheckMode fix, int64_t l2_offset,
> +                                int l2_index, bool active,
> +                                const char *fmt, ...)
> +{
> +    int ret;
> +    int ign = active ? QCOW2_OL_ACTIVE_L2 : QCOW2_OL_INACTIVE_L2;
> +    uint64_t l2_entry = QCOW_OFLAG_ZERO;
> +    va_list args;
> +
> +    va_start(args, fmt);
> +    ret = fix_table_entry(bs, res, fix, "L2", l2_offset, l2_index, l2_entry,
> +                          ign, fmt, args);
> +    va_end(args);
> +
> +    return ret;
> +}

If you drop the fprintf() from fix_table_entry(), this function will
make less sense as well.  Just calling fix_table_entry() directly will
be just as easy.

(Yes, I see that you use the function in patch 7 again, and yes, you'd
have to use a full line for the "active ?:" ternary, but still.)

Max

08.10.2018 22:54, Max Reitz wrote:
> On 17.08.18 14:22, Vladimir Sementsov-Ogievskiy wrote:
>> Split entry repairing to separate function, to be reused later.
>>
>> Note: entry in in-memory l2 table (local variable in
>> check_refcounts_l2) is not updated after this patch.
>>
>> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
>> ---
>>   block/qcow2-refcount.c | 147 ++++++++++++++++++++++++++++++++++++-------------
>>   1 file changed, 109 insertions(+), 38 deletions(-)
>>
>> diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
>> index 3b057b635d..d9c8cd666b 100644
>> --- a/block/qcow2-refcount.c
>> +++ b/block/qcow2-refcount.c
>> @@ -1554,6 +1554,99 @@ enum {
>>       CHECK_FRAG_INFO = 0x2,      /* update BlockFragInfo counters */
>>   };
>>   
>> +/* Update entry in L1 or L2 table
>> + *
>> + * Returns: -errno if overlap check failed
>> + *          0 if write failed
>> + *          1 on success
>> + */
>> +static int write_table_entry(BlockDriverState *bs, const char *table_name,
>> +                             uint64_t table_offset, int entry_index,
>> +                             uint64_t new_val, int ign)
>> +{
>> +    int ret;
>> +    uint64_t entry_offset =
>> +            table_offset + (uint64_t)entry_index * sizeof(new_val);
>> +
>> +    cpu_to_be64s(&new_val);
>> +    ret = qcow2_pre_write_overlap_check(bs, ign, entry_offset, sizeof(new_val));
>> +    if (ret < 0) {
>> +        fprintf(stderr,
>> +                "ERROR: Can't write %s table entry: overlap check failed: %s\n",
> I recently complained to Berto that I don't like elisions ("can't") in
> user interfaces, so I suppose I'll have to complain here, too, that I'd
> prefer a "Cannot".
>
>> +                table_name, strerror(-ret));
>> +        return ret;
>> +    }
>> +
>> +    ret = bdrv_pwrite_sync(bs->file, entry_offset, &new_val, sizeof(new_val));
>> +    if (ret < 0) {
>> +        fprintf(stderr, "ERROR: Failed to overwrite %s table entry: %s\n",
>> +                table_name, strerror(-ret));
>> +        return 0;
>> +    }
>> +
>> +    return 1;
>> +}
>> +
>> +/* Try to fix (if allowed) entry in L1 or L2 table. Update @res correspondingly.
>> + *
>> + * Returns: -errno if overlap check failed
>> + *          0 if entry was not updated for other reason
>> + *            (fixing disabled or write failed)
>> + *          1 on success
>> + */
>> +static int fix_table_entry(BlockDriverState *bs, BdrvCheckResult *res,
>> +                           BdrvCheckMode fix, const char *table_name,
>> +                           uint64_t table_offset, int entry_index,
>> +                           uint64_t new_val, int ign,
>> +                           const char *fmt, va_list args)
>> +{
>> +    int ret;
>> +
>> +    fprintf(stderr, fix & BDRV_FIX_ERRORS ? "Repairing: " : "ERROR: ");
>> +    vfprintf(stderr, fmt, args);
>> +    fprintf(stderr, "\n");
> If you're just going to print this here, right at the start, I think it
> would be better to just do it in the caller.
>
> Sure, with this solution the caller safes an fprintf() call, but I find
> it a bit over the top to start with vararg handling here when the caller
> can just do an additional fprintf().
>
> (Also, I actually find it clearer if you have to call two separate
> functions.)
>
>> +
>> +    if (!(fix & BDRV_FIX_ERRORS)) {
>> +        res->corruptions++;
>> +        return 0;
>> +    }

hmm, after dropping printfs, this if becomes strange too. it's the only 
use of "fix", and not correspond to function name (correspond to 
comments, but it's a bad reason).

>> +
>> +    ret = write_table_entry(bs, table_name, table_offset, entry_index, new_val,
>> +                            ign);
>> +
>> +    if (ret == 1) {
>> +        res->corruptions_fixed++;
>> +    } else {
>> +        res->check_errors++;
>> +    }
>> +
>> +    return ret;
>> +}
>> +
>> +/* Make L2 entry to be QCOW2_CLUSTER_ZERO_PLAIN
>> + *
>> + * Returns: -errno if overlap check failed
>> + *          0 if write failed
>> + *          1 on success
>> + */
>> +static int fix_l2_entry_to_zero(BlockDriverState *bs, BdrvCheckResult *res,
>> +                                BdrvCheckMode fix, int64_t l2_offset,
>> +                                int l2_index, bool active,
>> +                                const char *fmt, ...)
>> +{
>> +    int ret;
>> +    int ign = active ? QCOW2_OL_ACTIVE_L2 : QCOW2_OL_INACTIVE_L2;
>> +    uint64_t l2_entry = QCOW_OFLAG_ZERO;
>> +    va_list args;
>> +
>> +    va_start(args, fmt);
>> +    ret = fix_table_entry(bs, res, fix, "L2", l2_offset, l2_index, l2_entry,
>> +                          ign, fmt, args);
>> +    va_end(args);
>> +
>> +    return ret;
>> +}
> If you drop the fprintf() from fix_table_entry(), this function will
> make less sense as well.  Just calling fix_table_entry() directly will
> be just as easy.
>
> (Yes, I see that you use the function in patch 7 again, and yes, you'd
> have to use a full line for the "active ?:" ternary, but still.)
>
> Max
>


-- 
Best regards,
Vladimir