[Qemu-devel] [PATCH v3 0/6] Live block commit

[Qemu-devel] [PATCH v3 0/6] Live block commit

[Jeff Cody]

This series adds the basic case, of a live commit between two
images below the active layer, e.g.:

[base] <--- [snp-1] <--- [snp-2] <--- [snp-3] <--- [active]

can be collapsed down via commit, into:

[base] <--- [active]

or,

[base] <--- [snp-1] <--- [active],

[base] <--- [snp-3] <--- [active],

etc..

TODO:  'stage-2' of live commit functionality, to be able to push down the
        active layer. 

These changes are all reflected in my github repo:

    git://github.com/codyprime/qemu-kvm-jtc.git  branch: jtc-live-commit-1.3-v9

Changes from v2 -> v3:
===================================

Patch 1/6:  Comment cleanup, code cleanup
Patch 2/6:  Added additional sanity checks for base & top:
                - check if top == active
                - check if top == base
                - check if top & base args are reversed
Patch 5/6:  Made top = active as the default, however 'top' argument
            is now non-optional.
Patch 6/6:  Added 6 more tests to the qemu-io test:
                - top == base
                - top is a non-existent file
                - base is a non-existent file
                - top == active
                - top and base are reversed
                - top is omitted
Patch 7/7 (old): dropped, already applied


Changes from v1 -> v2:
===================================

Patch 1/7: [Eric] - Commit message cleanup
                  - Make comments clearer
                  - fixed whitespace removal

Dropped old Patch 4/8 (new qerror message) - Eric

Patch 2/7:        - Changed error_set() to error_setg()

Patch 5/7: [Eric] - Changed error_set() to error_setg()
                  - Updated comments/docs to be clearer
                  - fixed whitespace removal


Changes from RFC to v1:
===================================

* Feedback incorporated (see below)
* qemu-iotests added
* live snapshots have active->backing_hd reopened read-only.

Patch 1/8: [Kevin] -  Rename bdrv_delete_intermediate() to
                      bdrv_drop_intermediate()
                   -  Change terminology from 'child' to 'overlay'
                   -  Do not allow top == active, and return NULL for error,
                      simplified some logic.

Patch 2/8: [Kevin]       - Preserve errors in commit_populate()
           [Kevin, Eric] - Check that there is enough room in base, and resize
                           with bdrv_truncate() if not.
           [Jeff]        - Switch from 'child' to 'overlay' terminology
                         - Fixed up more error checking
                         - Minor cleanup
           [Kevin]       - Perform the bdrv_reopen() inside commit_start(),
                           instead of in blockdev.c

Patch 3/8: [Paolo]  - Rearranged patch, so the forward declaration is gone
            
Patch 4/8: None
Patch 5/8: None

Patch 6/8: [Eric]   - Updated QMP/qmp-events.txt with the new 'type' field
           [Kevin]  - If base cannot be found, return attempted base name
                    - Moved reopen() logic to commit_start
                    - Fixed comments in JSON command header
           [Jeff]   - If 'top' is not specified, default to active->backing_hd

Patch 7/8: New - simple qemu-iotest for commit.

Patch 8/8: New - after live snapshot, use bdrv_reopen() to reopen
                 active->backing_hd read-only.



Changes from the RFC v1 -> RFC v2:
===================================

* This patch series is not on top of Paolo's blk mirror series yet, to make it
  easier to apply independently if desired.  This means some of what was in the
  previous RFC series is not in this one (BlockdevOnError, for instance), but
  that can be easily added in once Paolo's series are in.

* This patches series is dependent on the reopen() series with transactional
  reopen.

* The target release for this series is 1.3

* Found some mistakes in the reopen calls

* Dropped the BlockdevOnError argument (for now), will add in if rebasing on
  top of Paolo's series.

* Used the new qerror system

Jeff Cody (6):
  block: add support functions for live commit, to find and delete
    images.
  block: add live block commit functionality
  blockdev: rename block_stream_cb to a generic block_job_cb
  block: helper function, to find the base image of a chain
  QAPI: add command for live block commit, 'block-commit'
  qemu-iotests: add initial tests for live block commit

 QMP/qmp-events.txt         |   6 +-
 block.c                    | 159 +++++++++++++++++++++++++++
 block.h                    |   5 +
 block/Makefile.objs        |   1 +
 block/commit.c             | 267 +++++++++++++++++++++++++++++++++++++++++++++
 block_int.h                |  16 +++
 blockdev.c                 |  64 ++++++++++-
 qapi-schema.json           |  34 ++++++
 qmp-commands.hx            |   6 +
 tests/qemu-iotests/040     | 178 ++++++++++++++++++++++++++++++
 tests/qemu-iotests/040.out |   5 +
 tests/qemu-iotests/group   |   1 +
 trace-events               |   4 +-
 13 files changed, 740 insertions(+), 6 deletions(-)
 create mode 100644 block/commit.c
 create mode 100755 tests/qemu-iotests/040
 create mode 100644 tests/qemu-iotests/040.out

-- 
1.7.11.4

[Qemu-devel] [PATCH v3 1/6] block: add support functions for live commit, to find and delete images.

[Jeff Cody]

Add bdrv_find_overlay(), and bdrv_drop_intermediate().

bdrv_find_overlay():  given 'bs' and the active (topmost) BDS of an image chain,
                    find the image that is the immediate top of 'bs'

bdrv_drop_intermediate():
                    Given 3 BDS (active, top, base), drop images above
                    base up to and including top, and set base to be the
                    backing file of top's overlay node.

                    E.g., this converts:

                    bottom <- base <- intermediate <- top <- active

                    to

                    bottom <- base <- active

Signed-off-by: Jeff Cody <jcody@redhat.com>
---
 block.c | 143 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 block.h |   4 ++
 2 files changed, 147 insertions(+)

diff --git a/block.c b/block.c
index 751ebdc..54209a5 100644
--- a/block.c
+++ b/block.c
@@ -1724,6 +1724,149 @@ int bdrv_change_backing_file(BlockDriverState *bs,
     return ret;
 }
 
+/*
+ * Finds the image layer in the chain that has 'bs' as its backing file.
+ *
+ * active is the current topmost image.
+ *
+ * Returns NULL if bs is not found in active's image chain,
+ * or if active == bs.
+ */
+BlockDriverState *bdrv_find_overlay(BlockDriverState *active,
+                                    BlockDriverState *bs)
+{
+    BlockDriverState *overlay = NULL;
+    BlockDriverState *intermediate;
+
+    assert(active != NULL);
+    assert(bs != NULL);
+
+    /* if bs is the same as active, then by definition it has no overlay
+     */
+    if (active == bs) {
+        return NULL;
+    }
+
+    intermediate = active;
+    while (intermediate->backing_hd) {
+        if (intermediate->backing_hd == bs) {
+            overlay = intermediate;
+            break;
+        }
+        intermediate = intermediate->backing_hd;
+    }
+
+    return overlay;
+}
+
+typedef struct BlkIntermediateStates {
+    BlockDriverState *bs;
+    QSIMPLEQ_ENTRY(BlkIntermediateStates) entry;
+} BlkIntermediateStates;
+
+
+/*
+ * Drops images above 'base' up to and including 'top', and sets the image
+ * above 'top' to have base as its backing file.
+ *
+ * Requires that the overlay to 'top' is opened r/w, so that the backing file
+ * information in 'bs' can be properly updated.
+ *
+ * E.g., this will convert the following chain:
+ * bottom <- base <- intermediate <- top <- active
+ *
+ * to
+ *
+ * bottom <- base <- active
+ *
+ * It is allowed for bottom==base, in which case it converts:
+ *
+ * base <- intermediate <- top <- active
+ *
+ * to
+ *
+ * base <- active
+ *
+ * Error conditions:
+ *  if active == top, that is considered an error
+ *
+ */
+int bdrv_drop_intermediate(BlockDriverState *active, BlockDriverState *top,
+                           BlockDriverState *base)
+{
+    BlockDriverState *intermediate;
+    BlockDriverState *base_bs = NULL;
+    BlockDriverState *new_top_bs = NULL;
+    BlkIntermediateStates *intermediate_state, *next;
+    int ret = -EIO;
+
+    QSIMPLEQ_HEAD(states_to_delete, BlkIntermediateStates) states_to_delete;
+    QSIMPLEQ_INIT(&states_to_delete);
+
+    if (!top->drv || !base->drv) {
+        goto exit;
+    }
+
+    new_top_bs = bdrv_find_overlay(active, top);
+
+    if (new_top_bs == NULL) {
+        /* we could not find the image above 'top', this is an error */
+        goto exit;
+    }
+
+    /* special case of new_top_bs->backing_hd already pointing to base - nothing
+     * to do, no intermediate images */
+    if (new_top_bs->backing_hd == base) {
+        ret = 0;
+        goto exit;
+    }
+
+    intermediate = top;
+
+    /* now we will go down through the list, and add each BDS we find
+     * into our deletion queue, until we hit the 'base'
+     */
+    while (intermediate) {
+        intermediate_state = g_malloc0(sizeof(BlkIntermediateStates));
+        intermediate_state->bs = intermediate;
+        QSIMPLEQ_INSERT_TAIL(&states_to_delete, intermediate_state, entry);
+
+        if (intermediate->backing_hd == base) {
+            base_bs = intermediate->backing_hd;
+            break;
+        }
+        intermediate = intermediate->backing_hd;
+    }
+    if (base_bs == NULL) {
+        /* something went wrong, we did not end at the base. safely
+         * unravel everything, and exit with error */
+        goto exit;
+    }
+
+    /* success - we can delete the intermediate states, and link top->base */
+    ret = bdrv_change_backing_file(new_top_bs, base_bs->filename,
+                                   base_bs->drv ? base_bs->drv->format_name : "");
+    if (ret) {
+        goto exit;
+    }
+    new_top_bs->backing_hd = base_bs;
+
+
+    QSIMPLEQ_FOREACH_SAFE(intermediate_state, &states_to_delete, entry, next) {
+        /* so that bdrv_close() does not recursively close the chain */
+        intermediate_state->bs->backing_hd = NULL;
+        bdrv_delete(intermediate_state->bs);
+    }
+    ret = 0;
+
+exit:
+    QSIMPLEQ_FOREACH_SAFE(intermediate_state, &states_to_delete, entry, next) {
+        g_free(intermediate_state);
+    }
+    return ret;
+}
+
+
 static int bdrv_check_byte_request(BlockDriverState *bs, int64_t offset,
                                    size_t size)
 {
diff --git a/block.h b/block.h
index b1095d8..8c9b424 100644
--- a/block.h
+++ b/block.h
@@ -203,6 +203,10 @@ int bdrv_commit_all(void);
 int bdrv_change_backing_file(BlockDriverState *bs,
     const char *backing_file, const char *backing_fmt);
 void bdrv_register(BlockDriver *bdrv);
+int bdrv_drop_intermediate(BlockDriverState *active, BlockDriverState *top,
+                           BlockDriverState *base);
+BlockDriverState *bdrv_find_overlay(BlockDriverState *active,
+                                    BlockDriverState *bs);
 
 
 typedef struct BdrvCheckResult {
-- 
1.7.11.4

[Qemu-devel] [PATCH v3 2/6] block: add live block commit functionality

[Jeff Cody]

This adds the live commit coroutine.  This iteration focuses on the
commit only below the active layer, and not the active layer itself.

The behaviour is similar to block streaming; the sectors are walked
through, and anything that exists above 'base' is committed back down
into base.  At the end, intermediate images are deleted, and the
chain stitched together.  Images are restored to their original open
flags upon completion.

Signed-off-by: Jeff Cody <jcody@redhat.com>
---
 block/Makefile.objs |   1 +
 block/commit.c      | 267 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 block_int.h         |  16 ++++
 trace-events        |   2 +
 4 files changed, 286 insertions(+)
 create mode 100644 block/commit.c

diff --git a/block/Makefile.objs b/block/Makefile.objs
index b5754d3..4a136b8 100644
--- a/block/Makefile.objs
+++ b/block/Makefile.objs
@@ -4,6 +4,7 @@ block-obj-y += qed.o qed-gencb.o qed-l2-cache.o qed-table.o qed-cluster.o
 block-obj-y += qed-check.o
 block-obj-y += parallels.o nbd.o blkdebug.o sheepdog.o blkverify.o
 block-obj-y += stream.o
+block-obj-y += commit.o
 block-obj-$(CONFIG_WIN32) += raw-win32.o
 block-obj-$(CONFIG_POSIX) += raw-posix.o
 block-obj-$(CONFIG_LIBISCSI) += iscsi.o
diff --git a/block/commit.c b/block/commit.c
new file mode 100644
index 0000000..624ec5f
--- /dev/null
+++ b/block/commit.c
@@ -0,0 +1,267 @@
+/*
+ * Live block commit
+ *
+ * Copyright Red Hat, Inc. 2012
+ *
+ * Authors:
+ *  Jeff Cody   <jcody@redhat.com>
+ *  Based on stream.c by Stefan Hajnoczi
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2 or later.
+ * See the COPYING.LIB file in the top-level directory.
+ *
+ */
+
+#include "trace.h"
+#include "block_int.h"
+#include "qemu/ratelimit.h"
+
+enum {
+    /*
+     * Size of data buffer for populating the image file.  This should be large
+     * enough to process multiple clusters in a single call, so that populating
+     * contiguous regions of the image is efficient.
+     */
+    COMMIT_BUFFER_SIZE = 512 * 1024, /* in bytes */
+};
+
+#define SLICE_TIME 100000000ULL /* ns */
+
+typedef struct CommitBlockJob {
+    BlockJob common;
+    RateLimit limit;
+    BlockDriverState *active;
+    BlockDriverState *top;
+    BlockDriverState *base;
+    BlockErrorAction on_error;
+    int base_flags;
+    int orig_overlay_flags;
+} CommitBlockJob;
+
+static int coroutine_fn commit_populate(BlockDriverState *bs,
+                                        BlockDriverState *base,
+                                        int64_t sector_num, int nb_sectors,
+                                        void *buf)
+{
+    int ret = 0;
+
+    ret = bdrv_read(bs, sector_num, buf, nb_sectors);
+    if (ret) {
+        return ret;
+    }
+
+    ret = bdrv_write(base, sector_num, buf, nb_sectors);
+    if (ret) {
+        return ret;
+    }
+
+    return 0;
+}
+
+static void coroutine_fn commit_run(void *opaque)
+{
+    CommitBlockJob *s = opaque;
+    BlockDriverState *active = s->active;
+    BlockDriverState *top = s->top;
+    BlockDriverState *base = s->base;
+    BlockDriverState *overlay_bs = NULL;
+    int64_t sector_num, end;
+    int ret = 0;
+    int n = 0;
+    void *buf;
+    int bytes_written = 0;
+    int64_t base_len;
+
+    ret = s->common.len = bdrv_getlength(top);
+
+
+    if (s->common.len < 0) {
+        goto exit_restore_reopen;
+    }
+
+    ret = base_len = bdrv_getlength(base);
+    if (base_len < 0) {
+        goto exit_restore_reopen;
+    }
+
+    if (base_len < s->common.len) {
+        ret = bdrv_truncate(base, s->common.len);
+        if (ret) {
+            goto exit_restore_reopen;
+        }
+    }
+
+    overlay_bs = bdrv_find_overlay(active, top);
+
+    end = s->common.len >> BDRV_SECTOR_BITS;
+    buf = qemu_blockalign(top, COMMIT_BUFFER_SIZE);
+
+    for (sector_num = 0; sector_num < end; sector_num += n) {
+        uint64_t delay_ns = 0;
+        bool copy;
+
+wait:
+        /* Note that even when no rate limit is applied we need to yield
+         * with no pending I/O here so that qemu_aio_flush() returns.
+         */
+        block_job_sleep_ns(&s->common, rt_clock, delay_ns);
+        if (block_job_is_cancelled(&s->common)) {
+            break;
+        }
+        /* Copy if allocated above the base */
+        ret = bdrv_co_is_allocated_above(top, base, sector_num,
+                                         COMMIT_BUFFER_SIZE / BDRV_SECTOR_SIZE,
+                                         &n);
+        copy = (ret == 1);
+        trace_commit_one_iteration(s, sector_num, n, ret);
+        if (copy) {
+            if (s->common.speed) {
+                delay_ns = ratelimit_calculate_delay(&s->limit, n);
+                if (delay_ns > 0) {
+                    goto wait;
+                }
+            }
+            ret = commit_populate(top, base, sector_num, n, buf);
+            bytes_written += n * BDRV_SECTOR_SIZE;
+        }
+        if (ret < 0) {
+            if (s->on_error == BLOCK_ERR_STOP_ANY    ||
+                s->on_error == BLOCK_ERR_REPORT      ||
+                (s->on_error == BLOCK_ERR_STOP_ENOSPC && ret == -ENOSPC)) {
+                goto exit_free_buf;
+            } else {
+                n = 0;
+                continue;
+            }
+        }
+        /* Publish progress */
+        s->common.offset += n * BDRV_SECTOR_SIZE;
+    }
+
+    ret = 0;
+
+    if (!block_job_is_cancelled(&s->common) && sector_num == end) {
+        /* success */
+        ret = bdrv_drop_intermediate(active, top, base);
+    }
+
+exit_free_buf:
+    qemu_vfree(buf);
+
+exit_restore_reopen:
+    /* restore base open flags here if appropriate (e.g., change the base back
+     * to r/o). These reopens do not need to be atomic, since we won't abort
+     * even on failure here */
+    if (s->base_flags != bdrv_get_flags(base)) {
+        bdrv_reopen(base, s->base_flags, NULL);
+    }
+    if (s->orig_overlay_flags != bdrv_get_flags(overlay_bs)) {
+        bdrv_reopen(overlay_bs, s->orig_overlay_flags, NULL);
+    }
+
+    block_job_complete(&s->common, ret);
+}
+
+static void commit_set_speed(BlockJob *job, int64_t speed, Error **errp)
+{
+    CommitBlockJob *s = container_of(job, CommitBlockJob, common);
+
+    if (speed < 0) {
+        error_set(errp, QERR_INVALID_PARAMETER, "speed");
+        return;
+    }
+    ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME);
+}
+
+static BlockJobType commit_job_type = {
+    .instance_size = sizeof(CommitBlockJob),
+    .job_type      = "commit",
+    .set_speed     = commit_set_speed,
+};
+
+void commit_start(BlockDriverState *bs, BlockDriverState *base,
+                  BlockDriverState *top, int64_t speed,
+                  BlockErrorAction on_error, BlockDriverCompletionFunc *cb,
+                  void *opaque, Error **errp)
+{
+    CommitBlockJob *s;
+    BlockReopenQueue *reopen_queue = NULL;
+    int orig_overlay_flags;
+    int orig_base_flags;
+    BlockDriverState *overlay_bs;
+    Error *local_err = NULL;
+
+    if ((on_error == BLOCK_ERR_STOP_ANY ||
+         on_error == BLOCK_ERR_STOP_ENOSPC) &&
+        !bdrv_iostatus_is_enabled(bs)) {
+        error_set(errp, QERR_INVALID_PARAMETER_COMBINATION);
+        return;
+    }
+
+    /* Once we support top == active layer, remove this check */
+    if (top == bs) {
+        error_setg(errp,
+                   "Top image as the active layer is currently unsupported");
+        return;
+    }
+
+    if (top == base) {
+        error_setg(errp, "Invalid files for merge: top and base are the same");
+        return;
+    }
+
+    /* top and base may be valid, but let's make sure that base is reachable
+     * from top */
+    if (bdrv_find_backing_image(top, base->filename) != base) {
+        error_setg(errp,
+                   "Base (%s) is not reachable from top (%s)",
+                   base->filename, top->filename);
+        return;
+    }
+
+    overlay_bs = bdrv_find_overlay(bs, top);
+
+    if (overlay_bs == NULL) {
+        error_setg(errp, "Could not find overlay image for %s:", top->filename);
+        return;
+    }
+
+    orig_base_flags    = bdrv_get_flags(base);
+    orig_overlay_flags = bdrv_get_flags(overlay_bs);
+
+    /* convert base & overlay_bs to r/w, if necessary */
+    if (!(orig_base_flags & BDRV_O_RDWR)) {
+        reopen_queue = bdrv_reopen_queue(reopen_queue, base,
+                                         orig_base_flags | BDRV_O_RDWR);
+    }
+    if (!(orig_overlay_flags & BDRV_O_RDWR)) {
+        reopen_queue = bdrv_reopen_queue(reopen_queue, overlay_bs,
+                                         orig_overlay_flags | BDRV_O_RDWR);
+    }
+    if (reopen_queue) {
+        bdrv_reopen_multiple(reopen_queue, &local_err);
+        if (local_err != NULL) {
+            error_propagate(errp, local_err);
+            return;
+        }
+    }
+
+
+    s = block_job_create(&commit_job_type, bs, speed, cb, opaque, errp);
+    if (!s) {
+        return;
+    }
+
+    s->base   = base;
+    s->top    = top;
+    s->active = bs;
+
+    s->base_flags          = orig_base_flags;
+    s->orig_overlay_flags  = orig_overlay_flags;
+
+    s->on_error = on_error;
+    s->common.co = qemu_coroutine_create(commit_run);
+
+    trace_commit_start(bs, base, top, s, s->common.co, opaque);
+    qemu_coroutine_enter(s->common.co, s);
+}
diff --git a/block_int.h b/block_int.h
index ac4245c..56164a7 100644
--- a/block_int.h
+++ b/block_int.h
@@ -463,4 +463,20 @@ void stream_start(BlockDriverState *bs, BlockDriverState *base,
                   BlockDriverCompletionFunc *cb,
                   void *opaque, Error **errp);
 
+/**
+ * commit_start:
+ * @bs: Top Block device
+ * @base: Block device that will be written into, and become the new top
+ * @speed: The maximum speed, in bytes per second, or 0 for unlimited.
+ * @on_error: The action to take upon error.
+ * @cb: Completion function for the job.
+ * @opaque: Opaque pointer value passed to @cb.
+ * @errp: Error object.
+ *
+ */
+void commit_start(BlockDriverState *bs, BlockDriverState *base,
+                 BlockDriverState *top, int64_t speed,
+                 BlockErrorAction on_error, BlockDriverCompletionFunc *cb,
+                 void *opaque, Error **errp);
+
 #endif /* BLOCK_INT_H */
diff --git a/trace-events b/trace-events
index f5b5097..dbc3007 100644
--- a/trace-events
+++ b/trace-events
@@ -74,6 +74,8 @@ bdrv_co_do_copy_on_readv(void *bs, int64_t sector_num, int nb_sectors, int64_t c
 # block/stream.c
 stream_one_iteration(void *s, int64_t sector_num, int nb_sectors, int is_allocated) "s %p sector_num %"PRId64" nb_sectors %d is_allocated %d"
 stream_start(void *bs, void *base, void *s, void *co, void *opaque) "bs %p base %p s %p co %p opaque %p"
+commit_one_iteration(void *s, int64_t sector_num, int nb_sectors, int is_allocated) "s %p sector_num %"PRId64" nb_sectors %d is_allocated %d"
+commit_start(void *bs, void *base, void *top, void *s, void *co, void *opaque) "bs %p base %p top %p s %p co %p opaque %p"
 
 # blockdev.c
 qmp_block_job_cancel(void *job) "job %p"
-- 
1.7.11.4

[Qemu-devel] [PATCH v3 3/6] blockdev: rename block_stream_cb to a generic block_job_cb

[Jeff Cody]

Signed-off-by: Jeff Cody <jcody@redhat.com>
---
 blockdev.c   | 6 +++---
 trace-events | 2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/blockdev.c b/blockdev.c
index 7c83baa..9caa16f 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1063,12 +1063,12 @@ static QObject *qobject_from_block_job(BlockJob *job)
                               job->speed);
 }
 
-static void block_stream_cb(void *opaque, int ret)
+static void block_job_cb(void *opaque, int ret)
 {
     BlockDriverState *bs = opaque;
     QObject *obj;
 
-    trace_block_stream_cb(bs, bs->job, ret);
+    trace_block_job_cb(bs, bs->job, ret);
 
     assert(bs->job);
     obj = qobject_from_block_job(bs->job);
@@ -1110,7 +1110,7 @@ void qmp_block_stream(const char *device, bool has_base,
     }
 
     stream_start(bs, base_bs, base, has_speed ? speed : 0,
-                 block_stream_cb, bs, &local_err);
+                 block_job_cb, bs, &local_err);
     if (error_is_set(&local_err)) {
         error_propagate(errp, local_err);
         return;
diff --git a/trace-events b/trace-events
index dbc3007..29771a7 100644
--- a/trace-events
+++ b/trace-events
@@ -79,7 +79,7 @@ commit_start(void *bs, void *base, void *top, void *s, void *co, void *opaque) "
 
 # blockdev.c
 qmp_block_job_cancel(void *job) "job %p"
-block_stream_cb(void *bs, void *job, int ret) "bs %p job %p ret %d"
+block_job_cb(void *bs, void *job, int ret) "bs %p job %p ret %d"
 qmp_block_stream(void *bs, void *job) "bs %p job %p"
 
 # hw/virtio-blk.c
-- 
1.7.11.4

[Qemu-devel] [PATCH v3 4/6] block: helper function, to find the base image of a chain

[Jeff Cody]

This is a simple helper function, that will return the base image
of a given image chain.

Signed-off-by: Jeff Cody <jcody@redhat.com>
---
 block.c | 16 ++++++++++++++++
 block.h |  1 +
 2 files changed, 17 insertions(+)

diff --git a/block.c b/block.c
index 54209a5..d7a6d14 100644
--- a/block.c
+++ b/block.c
@@ -3117,6 +3117,22 @@ int bdrv_get_backing_file_depth(BlockDriverState *bs)
     return 1 + bdrv_get_backing_file_depth(bs->backing_hd);
 }
 
+BlockDriverState *bdrv_find_base(BlockDriverState *bs)
+{
+    BlockDriverState *curr_bs = NULL;
+
+    if (!bs) {
+        return NULL;
+    }
+
+    curr_bs = bs;
+
+    while (curr_bs->backing_hd) {
+        curr_bs = curr_bs->backing_hd;
+    }
+    return curr_bs;
+}
+
 #define NB_SUFFIXES 4
 
 char *get_human_readable_size(char *buf, int buf_size, int64_t size)
diff --git a/block.h b/block.h
index 8c9b424..e9249c4 100644
--- a/block.h
+++ b/block.h
@@ -207,6 +207,7 @@ int bdrv_drop_intermediate(BlockDriverState *active, BlockDriverState *top,
                            BlockDriverState *base);
 BlockDriverState *bdrv_find_overlay(BlockDriverState *active,
                                     BlockDriverState *bs);
+BlockDriverState *bdrv_find_base(BlockDriverState *bs);
 
 
 typedef struct BdrvCheckResult {
-- 
1.7.11.4

[Qemu-devel] [PATCH v3 5/6] QAPI: add command for live block commit, 'block-commit'

[Jeff Cody]

The command for live block commit is added, which has the following
arguments:

device: the block device to perform the commit on (mandatory)
base:   the base image to commit into; optional (if not specified,
        it is the underlying original image)
top:    the top image of the commit - all data from inside top down
        to base will be committed into base (mandatory for now; see
        note, below)

speed:  maximum speed, in bytes/sec

Note: Eventually this command will support merging down the active layer,
      but that code is not yet complete.  If the active layer is passed
      in as top, then an error will be returned.  Once merging down the
      active layer is supported, the 'top' argument may become optional,
      and default to the active layer.

The is done as a block job, so upon completion a BLOCK_JOB_COMPLETED will
be emitted.

Signed-off-by: Jeff Cody <jcody@redhat.com>
---
 QMP/qmp-events.txt |  6 ++++--
 blockdev.c         | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 qapi-schema.json   | 34 ++++++++++++++++++++++++++++++++
 qmp-commands.hx    |  6 ++++++
 4 files changed, 102 insertions(+), 2 deletions(-)

diff --git a/QMP/qmp-events.txt b/QMP/qmp-events.txt
index 2878058..4491020 100644
--- a/QMP/qmp-events.txt
+++ b/QMP/qmp-events.txt
@@ -50,7 +50,8 @@ Emitted when a block job has been cancelled.
 
 Data:
 
-- "type":     Job type ("stream" for image streaming, json-string)
+- "type":     Job type (json-string; "stream" for image streaming
+                                     "commit" for block commit)
 - "device":   Device name (json-string)
 - "len":      Maximum progress value (json-int)
 - "offset":   Current progress value (json-int)
@@ -73,7 +74,8 @@ Emitted when a block job has completed.
 
 Data:
 
-- "type":     Job type ("stream" for image streaming, json-string)
+- "type":     Job type (json-string; "stream" for image streaming
+                                     "commit" for block commit)
 - "device":   Device name (json-string)
 - "len":      Maximum progress value (json-int)
 - "offset":   Current progress value (json-int)
diff --git a/blockdev.c b/blockdev.c
index 9caa16f..946e3c2 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1124,6 +1124,64 @@ void qmp_block_stream(const char *device, bool has_base,
     trace_qmp_block_stream(bs, bs->job);
 }
 
+void qmp_block_commit(const char *device,
+                      bool has_base, const char *base, const char *top,
+                      bool has_speed, int64_t speed,
+                      Error **errp)
+{
+    BlockDriverState *bs;
+    BlockDriverState *base_bs, *top_bs;
+    Error *local_err = NULL;
+    /* This will be part of the QMP command, if/when the
+     * BlockdevOnError change for blkmirror makes it in
+     */
+    BlockErrorAction on_error = BLOCK_ERR_REPORT;
+
+    /* drain all i/o before commits */
+    bdrv_drain_all();
+
+    bs = bdrv_find(device);
+    if (!bs) {
+        error_set(errp, QERR_DEVICE_NOT_FOUND, device);
+        return;
+    }
+    if (base && has_base) {
+        base_bs = bdrv_find_backing_image(bs, base);
+    } else {
+        base_bs = bdrv_find_base(bs);
+    }
+
+    if (base_bs == NULL) {
+        error_set(errp, QERR_BASE_NOT_FOUND, base ? base : "NULL");
+        return;
+    }
+
+    /* default top_bs is the active layer */
+    top_bs = bs;
+
+    if (top) {
+        if (strcmp(bs->filename, top) != 0) {
+            top_bs = bdrv_find_backing_image(bs, top);
+        }
+    }
+
+    if (top_bs == NULL) {
+        error_setg(errp, "Top image file %s not found", top ? top : "NULL");
+        return;
+    }
+
+    commit_start(bs, base_bs, top_bs, speed, on_error, block_job_cb, bs,
+                &local_err);
+    if (local_err != NULL) {
+        error_propagate(errp, local_err);
+        return;
+    }
+    /* Grab a reference so hotplug does not delete the BlockDriverState from
+     * underneath us.
+     */
+    drive_get_ref(drive_get_by_blockdev(bs));
+}
+
 static BlockJob *find_block_job(const char *device)
 {
     BlockDriverState *bs;
diff --git a/qapi-schema.json b/qapi-schema.json
index 14e4419..5816545 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -1468,6 +1468,40 @@
   'returns': 'str' }
 
 ##
+# @block-commit
+#
+# Live commit of data from overlay image nodes into backing nodes - i.e.,
+# writes data between 'top' and 'base' into 'base'.
+#
+# @device:  the name of the device
+#
+# @base:   #optional The file name of the backing image to write data into.
+#                    If not specified, this is the deepest backing image
+#
+# @top:              The file name of the backing image within the image chain,
+#                    which contains the topmost data to be committed down.
+#                    Note, the active layer as 'top' is currently unsupported.
+#
+#                    If top == base, that is an error.
+#
+#
+# @speed:  #optional the maximum speed, in bytes per second
+#
+# Returns: Nothing on success
+#          If commit or stream is already active on this device, DeviceInUse
+#          If @device does not exist, DeviceNotFound
+#          If image commit is not supported by this device, NotSupported
+#          If @base or @top is invalid, a generic error is returned
+#          If @top is the active layer, or omitted, a generic error is returned
+#          If @speed is invalid, InvalidParameter
+#
+# Since: 1.3
+#
+##
+{ 'command': 'block-commit',
+  'data': { 'device': 'str', '*base': 'str', 'top': 'str',
+            '*speed': 'int' } }
+
 # @migrate_cancel
 #
 # Cancel the current executing migration process.
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 6e21ddb..e244763 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -792,6 +792,12 @@ EQMP
     },
 
     {
+        .name       = "block-commit",
+        .args_type  = "device:B,base:s?,top:s?,speed:o?",
+        .mhandler.cmd_new = qmp_marshal_input_block_commit,
+    },
+
+    {
         .name       = "block-job-set-speed",
         .args_type  = "device:B,speed:o",
         .mhandler.cmd_new = qmp_marshal_input_block_job_set_speed,
-- 
1.7.11.4

[Qemu-devel] [PATCH v3 6/6] qemu-iotests: add initial tests for live block commit

[Jeff Cody]

Derived from the streaming test cases (030), this adds the
following 9 tests:

1. For the following image chain, commit [mid] into [backing],
   and use qemu-io to verify [backing] has its original data, as
   well as the data from [mid]

           [backing] <-- [mid] <-- [test]

2. Verifies that 'block-commit' with the 'speed' parameter sets the
   speed parameter, as reported by 'query-block-jobs'

3. Verifies that a bogus 'device' parameter to 'block-commit'
   results in error

4-9: Appropriate error values returned for the following argument errors:
    * top == base
    * top is nonexistent
    * base is nonexistent
    * top == active layer (this is currently not supported)
    * top and base arguments are reversed
    * top argument is omitted

Signed-off-by: Jeff Cody <jcody@redhat.com>
---
 tests/qemu-iotests/040     | 178 +++++++++++++++++++++++++++++++++++++++++++++
 tests/qemu-iotests/040.out |   5 ++
 tests/qemu-iotests/group   |   1 +
 3 files changed, 184 insertions(+)
 create mode 100755 tests/qemu-iotests/040
 create mode 100644 tests/qemu-iotests/040.out

diff --git a/tests/qemu-iotests/040 b/tests/qemu-iotests/040
new file mode 100755
index 0000000..6c3cc6a
--- /dev/null
+++ b/tests/qemu-iotests/040
@@ -0,0 +1,178 @@
+#!/usr/bin/env python
+#
+# Tests for image block commit.
+#
+# Copyright (C) 2012 IBM, Corp.
+# Copyright (C) 2012 Red Hat, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+# Test for live block commit
+# Derived from Image Streaming Test 030
+
+import time
+import os
+import iotests
+from iotests import qemu_img, qemu_io
+import struct
+
+backing_img = os.path.join(iotests.test_dir, 'backing.img')
+mid_img = os.path.join(iotests.test_dir, 'mid.img')
+test_img = os.path.join(iotests.test_dir, 'test.img')
+
+class ImageCommitTestCase(iotests.QMPTestCase):
+    '''Abstract base class for image commit test cases'''
+
+    def assert_no_active_commit(self):
+        result = self.vm.qmp('query-block-jobs')
+        self.assert_qmp(result, 'return', [])
+
+    def cancel_and_wait(self, drive='drive0'):
+        '''Cancel a block job and wait for it to finish'''
+        result = self.vm.qmp('block-job-cancel', device=drive)
+        self.assert_qmp(result, 'return', {})
+
+        cancelled = False
+        while not cancelled:
+            for event in self.vm.get_qmp_events(wait=True):
+                if event['event'] == 'BLOCK_JOB_CANCELLED':
+                    self.assert_qmp(event, 'data/type', 'commit')
+                    self.assert_qmp(event, 'data/device', drive)
+                    cancelled = True
+
+        self.assert_no_active_commit()
+
+    def create_image(self, name, size):
+        file = open(name, 'w')
+        i = 0
+        while i < size:
+            sector = struct.pack('>l504xl', i / 512, i / 512)
+            file.write(sector)
+            i = i + 512
+        file.close()
+
+
+class TestSingleDrive(ImageCommitTestCase):
+    image_len = 1 * 1024 * 1024
+    test_len = 1 * 1024 * 256
+
+    def setUp(self):
+        self.create_image(backing_img, TestSingleDrive.image_len)
+        qemu_img('create', '-f', iotests.imgfmt, '-o', 'backing_file=%s' % backing_img, mid_img)
+        qemu_img('create', '-f', iotests.imgfmt, '-o', 'backing_file=%s' % mid_img, test_img)
+        qemu_io('-c', 'write -P 0xab 0 524288', backing_img)
+        qemu_io('-c', 'write -P 0xef 524288 524288', mid_img)
+        self.vm = iotests.VM().add_drive(test_img)
+        self.vm.launch()
+
+    def tearDown(self):
+        self.vm.shutdown()
+        os.remove(test_img)
+        os.remove(mid_img)
+        os.remove(backing_img)
+
+    def test_commit(self):
+        self.assert_no_active_commit()
+        result = self.vm.qmp('block-commit', device='drive0', top='%s' % mid_img)
+        self.assert_qmp(result, 'return', {})
+
+        completed = False
+        while not completed:
+            for event in self.vm.get_qmp_events(wait=True):
+                if event['event'] == 'BLOCK_JOB_COMPLETED':
+                    self.assert_qmp(event, 'data/type', 'commit')
+                    self.assert_qmp(event, 'data/device', 'drive0')
+                    self.assert_qmp(event, 'data/offset', self.image_len)
+                    self.assert_qmp(event, 'data/len', self.image_len)
+                    completed = True
+
+        self.assert_no_active_commit()
+        self.vm.shutdown()
+
+        self.assertEqual(-1, qemu_io('-c', 'read -P 0xab 0 524288', backing_img).find("verification failed"))
+        self.assertEqual(-1, qemu_io('-c', 'read -P 0xef 524288 524288', backing_img).find("verification failed"))
+
+    def test_device_not_found(self):
+        result = self.vm.qmp('block-commit', device='nonexistent', top='%s' % mid_img)
+        self.assert_qmp(result, 'error/class', 'DeviceNotFound')
+
+    def test_top_same_base(self):
+        self.assert_no_active_commit()
+        result = self.vm.qmp('block-commit', device='drive0', top='%s' % backing_img, base='%s' % backing_img)
+        self.assert_qmp(result, 'error/class', 'GenericError')
+        self.assert_qmp(result, 'error/desc', 'Invalid files for merge: top and base are the same')
+
+    def test_top_invalid(self):
+        self.assert_no_active_commit()
+        result = self.vm.qmp('block-commit', device='drive0', top='badfile', base='%s' % backing_img)
+        self.assert_qmp(result, 'error/class', 'GenericError')
+        self.assert_qmp(result, 'error/desc', 'Top image file badfile not found')
+
+    def test_base_invalid(self):
+        self.assert_no_active_commit()
+        result = self.vm.qmp('block-commit', device='drive0', top='%s' % mid_img, base='badfile')
+        self.assert_qmp(result, 'error/class', 'GenericError')
+        self.assert_qmp(result, 'error/desc', 'Base \'badfile\' not found')
+
+    def test_top_is_active(self):
+        self.assert_no_active_commit()
+        result = self.vm.qmp('block-commit', device='drive0', top='%s' % test_img, base='%s' % backing_img)
+        self.assert_qmp(result, 'error/class', 'GenericError')
+        self.assert_qmp(result, 'error/desc', 'Top image as the active layer is currently unsupported')
+
+    def test_top_and_base_reversed(self):
+        self.assert_no_active_commit()
+        result = self.vm.qmp('block-commit', device='drive0', top='%s' % backing_img, base='%s' % mid_img)
+        self.assert_qmp(result, 'error/class', 'GenericError')
+        self.assert_qmp(result, 'error/desc', 'Base (%(1)s) is not reachable from top (%(2)s)' % {"1" : mid_img, "2" : backing_img})
+
+    def test_top_omitted(self):
+        self.assert_no_active_commit()
+        result = self.vm.qmp('block-commit', device='drive0')
+        self.assert_qmp(result, 'error/class', 'GenericError')
+        self.assert_qmp(result, 'error/desc', 'Invalid parameter type for \'top\', expected: string')
+
+
+class TestSetSpeed(ImageCommitTestCase):
+    image_len = 80 * 1024 * 1024 # MB
+
+    def setUp(self):
+        qemu_img('create', backing_img, str(TestSetSpeed.image_len))
+        qemu_img('create', '-f', iotests.imgfmt, '-o', 'backing_file=%s' % backing_img, mid_img)
+        qemu_img('create', '-f', iotests.imgfmt, '-o', 'backing_file=%s' % mid_img, test_img)
+        self.vm = iotests.VM().add_drive(test_img)
+        self.vm.launch()
+
+    def tearDown(self):
+        self.vm.shutdown()
+        os.remove(test_img)
+        os.remove(mid_img)
+        os.remove(backing_img)
+
+    def test_set_speed(self):
+        self.assert_no_active_commit()
+
+        result = self.vm.qmp('block-commit', device='drive0', top=mid_img, speed=1024 * 1024)
+        self.assert_qmp(result, 'return', {})
+
+        # Ensure the speed we set was accepted
+        result = self.vm.qmp('query-block-jobs')
+        self.assert_qmp(result, 'return[0]/device', 'drive0')
+        self.assert_qmp(result, 'return[0]/speed', 1024 * 1024)
+
+        self.cancel_and_wait()
+
+
+if __name__ == '__main__':
+    iotests.main(supported_fmts=['qcow2', 'qed'])
diff --git a/tests/qemu-iotests/040.out b/tests/qemu-iotests/040.out
new file mode 100644
index 0000000..dae404e
--- /dev/null
+++ b/tests/qemu-iotests/040.out
@@ -0,0 +1,5 @@
+.........
+----------------------------------------------------------------------
+Ran 9 tests
+
+OK
diff --git a/tests/qemu-iotests/group b/tests/qemu-iotests/group
index ebb5ca4..4b54fa6 100644
--- a/tests/qemu-iotests/group
+++ b/tests/qemu-iotests/group
@@ -46,3 +46,4 @@
 037 rw auto backing
 038 rw auto backing
 039 rw auto
+040 rw auto
-- 
1.7.11.4

Re: [Qemu-devel] [PATCH v3 5/6] QAPI: add command for live block commit, 'block-commit'

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 827 bytes --]

On 09/27/2012 11:29 AM, Jeff Cody wrote:
> The command for live block commit is added, which has the following
> arguments:
> 
> device: the block device to perform the commit on (mandatory)
> base:   the base image to commit into; optional (if not specified,
>         it is the underlying original image)
> top:    the top image of the commit - all data from inside top down
>         to base will be committed into base (mandatory for now; see
>         note, below)
> 

> +++ b/qmp-commands.hx
> @@ -792,6 +792,12 @@ EQMP
>      },
>  
>      {
> +        .name       = "block-commit",
> +        .args_type  = "device:B,base:s?,top:s?,speed:o?",

s/top:s?/top:s/ now that top is mandatory.

-- 
Eric Blake   eblake@redhat.com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH v3 0/6] Live block commit

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 1001 bytes --]

On 09/27/2012 11:29 AM, Jeff Cody wrote:
> This series adds the basic case, of a live commit between two
> images below the active layer, e.g.:
> 
> [base] <--- [snp-1] <--- [snp-2] <--- [snp-3] <--- [active]
> 
> can be collapsed down via commit, into:
> 
> [base] <--- [active]
> 

> Jeff Cody (6):
>   block: add support functions for live commit, to find and delete
>     images.
>   block: add live block commit functionality
>   blockdev: rename block_stream_cb to a generic block_job_cb
>   block: helper function, to find the base image of a chain
>   QAPI: add command for live block commit, 'block-commit'
>   qemu-iotests: add initial tests for live block commit

Series:

Reviewed-by: Eric Blake <eblake@redhat.com>

I found one minor problem in 5/6, and wonder if that can be fixed by
whoever sends the pull request without needing a full spin of v4.

-- 
Eric Blake   eblake@redhat.com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH v3 5/6] QAPI: add command for live block commit, 'block-commit'

[Jeff Cody]

On 09/27/2012 01:57 PM, Eric Blake wrote:
> On 09/27/2012 11:29 AM, Jeff Cody wrote:
>> The command for live block commit is added, which has the following
>> arguments:
>>
>> device: the block device to perform the commit on (mandatory)
>> base:   the base image to commit into; optional (if not specified,
>>         it is the underlying original image)
>> top:    the top image of the commit - all data from inside top down
>>         to base will be committed into base (mandatory for now; see
>>         note, below)
>>
> 
>> +++ b/qmp-commands.hx
>> @@ -792,6 +792,12 @@ EQMP
>>      },
>>  
>>      {
>> +        .name       = "block-commit",
>> +        .args_type  = "device:B,base:s?,top:s?,speed:o?",
> 
> s/top:s?/top:s/ now that top is mandatory.
> 

Right, forgot the hx file.  Although, QAPI catches it just fine
regardless of the hx file... but I will spin that really quick
(hopefully that is the only change required), unless Kevin wants to do
it when he pulls it into his branch.

Re: [Qemu-devel] [PATCH v3 0/6] Live block commit

[Kevin Wolf]

Am 27.09.2012 19:29, schrieb Jeff Cody:
> This series adds the basic case, of a live commit between two
> images below the active layer, e.g.:
> 
> [base] <--- [snp-1] <--- [snp-2] <--- [snp-3] <--- [active]
> 
> can be collapsed down via commit, into:
> 
> [base] <--- [active]
> 
> or,
> 
> [base] <--- [snp-1] <--- [active],
> 
> [base] <--- [snp-3] <--- [active],
> 
> etc..
> 
> TODO:  'stage-2' of live commit functionality, to be able to push down the
>         active layer. 
> 
> These changes are all reflected in my github repo:
> 
>     git://github.com/codyprime/qemu-kvm-jtc.git  branch: jtc-live-commit-1.3-v9

Thanks, applied all to the block branch.

Kevin