blkdebug: Add ability to override unmap geometries

Make it easier to simulate various unusual hardware setups (for
example, recent commits 3482b9b and b8d0a98 affect the Dell
Equallogic iSCSI with its 15M preferred and maximum unmap and
write zero sizing, or b2f95fe deals with the Linux loopback
block device having a max_transfer of 64k), by allowing blkdebug
to wrap any other device with further restrictions on various
alignments.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 20170429191419.30051-9-eblake@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>

2 files changed, 125 insertions, 4 deletions

diff --git a/block/blkdebug.c b/block/blkdebug.c
index 29ab7a3a8b..a5196e889d 100644
--- a/block/blkdebug.c
+++ b/block/blkdebug.c
@@ -39,6 +39,11 @@ typedef struct BDRVBlkdebugState {
     int state;
     int new_state;
     uint64_t align;
+    uint64_t max_transfer;
+    uint64_t opt_write_zero;
+    uint64_t max_write_zero;
+    uint64_t opt_discard;
+    uint64_t max_discard;
 
     /* For blkdebug_refresh_filename() */
     char *config_file;
@@ -343,6 +348,31 @@ static QemuOptsList runtime_opts = {
             .type = QEMU_OPT_SIZE,
             .help = "Required alignment in bytes",
         },
+        {
+            .name = "max-transfer",
+            .type = QEMU_OPT_SIZE,
+            .help = "Maximum transfer size in bytes",
+        },
+        {
+            .name = "opt-write-zero",
+            .type = QEMU_OPT_SIZE,
+            .help = "Optimum write zero alignment in bytes",
+        },
+        {
+            .name = "max-write-zero",
+            .type = QEMU_OPT_SIZE,
+            .help = "Maximum write zero size in bytes",
+        },
+        {
+            .name = "opt-discard",
+            .type = QEMU_OPT_SIZE,
+            .help = "Optimum discard alignment in bytes",
+        },
+        {
+            .name = "max-discard",
+            .type = QEMU_OPT_SIZE,
+            .help = "Maximum discard size in bytes",
+        },
         { /* end of list */ }
     },
 };
@@ -354,6 +384,7 @@ static int blkdebug_open(BlockDriverState *bs, QDict *options, int flags,
     QemuOpts *opts;
     Error *local_err = NULL;
     int ret;
+    uint64_t align;
 
     opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
     qemu_opts_absorb_qdict(opts, options, &local_err);
@@ -388,13 +419,61 @@ static int blkdebug_open(BlockDriverState *bs, QDict *options, int flags,
         bs->file->bs->supported_zero_flags;
     ret = -EINVAL;
 
-    /* Set request alignment */
+    /* Set alignment overrides */
     s->align = qemu_opt_get_size(opts, "align", 0);
     if (s->align && (s->align >= INT_MAX || !is_power_of_2(s->align))) {
         error_setg(errp, "Cannot meet constraints with align %" PRIu64,
                    s->align);
         goto out;
     }
+    align = MAX(s->align, bs->file->bs->bl.request_alignment);
+
+    s->max_transfer = qemu_opt_get_size(opts, "max-transfer", 0);
+    if (s->max_transfer &&
+        (s->max_transfer >= INT_MAX ||
+         !QEMU_IS_ALIGNED(s->max_transfer, align))) {
+        error_setg(errp, "Cannot meet constraints with max-transfer %" PRIu64,
+                   s->max_transfer);
+        goto out;
+    }
+
+    s->opt_write_zero = qemu_opt_get_size(opts, "opt-write-zero", 0);
+    if (s->opt_write_zero &&
+        (s->opt_write_zero >= INT_MAX ||
+         !QEMU_IS_ALIGNED(s->opt_write_zero, align))) {
+        error_setg(errp, "Cannot meet constraints with opt-write-zero %" PRIu64,
+                   s->opt_write_zero);
+        goto out;
+    }
+
+    s->max_write_zero = qemu_opt_get_size(opts, "max-write-zero", 0);
+    if (s->max_write_zero &&
+        (s->max_write_zero >= INT_MAX ||
+         !QEMU_IS_ALIGNED(s->max_write_zero,
+                          MAX(s->opt_write_zero, align)))) {
+        error_setg(errp, "Cannot meet constraints with max-write-zero %" PRIu64,
+                   s->max_write_zero);
+        goto out;
+    }
+
+    s->opt_discard = qemu_opt_get_size(opts, "opt-discard", 0);
+    if (s->opt_discard &&
+        (s->opt_discard >= INT_MAX ||
+         !QEMU_IS_ALIGNED(s->opt_discard, align))) {
+        error_setg(errp, "Cannot meet constraints with opt-discard %" PRIu64,
+                   s->opt_discard);
+        goto out;
+    }
+
+    s->max_discard = qemu_opt_get_size(opts, "max-discard", 0);
+    if (s->max_discard &&
+        (s->max_discard >= INT_MAX ||
+         !QEMU_IS_ALIGNED(s->max_discard,
+                          MAX(s->opt_discard, align)))) {
+        error_setg(errp, "Cannot meet constraints with max-discard %" PRIu64,
+                   s->max_discard);
+        goto out;
+    }
 
     ret = 0;
 out:
@@ -789,6 +868,21 @@ static void blkdebug_refresh_limits(BlockDriverState *bs, Error **errp)
     if (s->align) {
         bs->bl.request_alignment = s->align;
     }
+    if (s->max_transfer) {
+        bs->bl.max_transfer = s->max_transfer;
+    }
+    if (s->opt_write_zero) {
+        bs->bl.pwrite_zeroes_alignment = s->opt_write_zero;
+    }
+    if (s->max_write_zero) {
+        bs->bl.max_pwrite_zeroes = s->max_write_zero;
+    }
+    if (s->opt_discard) {
+        bs->bl.pdiscard_alignment = s->opt_discard;
+    }
+    if (s->max_discard) {
+        bs->bl.max_pdiscard = s->max_discard;
+    }
 }
 
 static int blkdebug_reopen_prepare(BDRVReopenState *reopen_state,
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 52e3ecd505..6b974b952f 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -2434,8 +2434,33 @@
 #
 # @config:          filename of the configuration file
 #
-# @align:           required alignment for requests in bytes,
-#                   must be power of 2, or 0 for default
+# @align:           required alignment for requests in bytes, must be
+#                   positive power of 2, or 0 for default
+#
+# @max-transfer:    maximum size for I/O transfers in bytes, must be
+#                   positive multiple of @align and of the underlying
+#                   file's request alignment (but need not be a power of
+#                   2), or 0 for default (since 2.10)
+#
+# @opt-write-zero:  preferred alignment for write zero requests in bytes,
+#                   must be positive multiple of @align and of the
+#                   underlying file's request alignment (but need not be a
+#                   power of 2), or 0 for default (since 2.10)
+#
+# @max-write-zero:  maximum size for write zero requests in bytes, must be
+#                   positive multiple of @align, of @opt-write-zero, and of
+#                   the underlying file's request alignment (but need not
+#                   be a power of 2), or 0 for default (since 2.10)
+#
+# @opt-discard:     preferred alignment for discard requests in bytes, must
+#                   be positive multiple of @align and of the underlying
+#                   file's request alignment (but need not be a power of
+#                   2), or 0 for default (since 2.10)
+#
+# @max-discard:     maximum size for discard requests in bytes, must be
+#                   positive multiple of @align, of @opt-discard, and of
+#                   the underlying file's request alignment (but need not
+#                   be a power of 2), or 0 for default (since 2.10)
 #
 # @inject-error:    array of error injection descriptions
 #
@@ -2446,7 +2471,9 @@
 { 'struct': 'BlockdevOptionsBlkdebug',
   'data': { 'image': 'BlockdevRef',
             '*config': 'str',
-            '*align': 'int',
+            '*align': 'int', '*max-transfer': 'int32',
+            '*opt-write-zero': 'int32', '*max-write-zero': 'int32',
+            '*opt-discard': 'int32', '*max-discard': 'int32',
             '*inject-error': ['BlkdebugInjectErrorOptions'],
             '*set-state': ['BlkdebugSetStateOptions'] } }