[PATCH 2 of 8] libxl: introduce libxl_set_relative_memory_target

[Stefano Stabellini <stefano.stabellini@eu.citrix.com>]

libxl: introduce libxl_set_relative_memory_target

Introduce libxl_set_relative_memory_target to modify the memory target
of a domain by a relative amount of memory in a single xenstore
transaction.
Modify libxl_set_memory_target to use xenstore transactions.
The first time we are reading/writing dom0 memory target, fill the
informations in xenstore if they are missing.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

diff -r 990ff10b7b00 tools/libxl/libxl.c
--- a/tools/libxl/libxl.c	Wed Aug 25 20:59:35 2010 +0100
+++ b/tools/libxl/libxl.c	Wed Aug 25 21:01:36 2010 +0100
@@ -2751,56 +2751,243 @@ out:
     return rc;
 }
 
+static int fill_dom0_memory_info(libxl_gc *gc, uint32_t *target_memkb)
+{
+    int rc;
+    libxl_dominfo info;
+    char *target = NULL, *endptr = NULL;
+    char *target_path = "/local/domain/0/memory/target";
+    char *max_path = "/local/domain/0/memory/static-max";
+    xs_transaction_t t;
+    libxl_ctx *ctx = libxl_gc_owner(gc);
+
+retry_transaction:
+    t = xs_transaction_start(ctx->xsh);
+
+    target = libxl_xs_read(gc, t, target_path);
+    if (target) {
+        *target_memkb = strtoul(target, &endptr, 10);
+        if (*endptr != '\0') {
+            XL_LOG_ERRNO(ctx, XL_LOG_ERROR,
+                    "invalid memory target %s from %s\n", target, target_path);
+            rc = ERROR_FAIL;
+            goto out;
+        }
+        rc = 0;
+        goto out;
+    }
+
+    rc = libxl_domain_info(ctx, &info, 0);
+    if (rc < 0)
+        return rc;
+
+    libxl_xs_write(gc, t, target_path, "%"PRIu32, (uint32_t) info.target_memkb);
+    libxl_xs_write(gc, t, max_path, "%"PRIu32, (uint32_t) info.max_memkb);
+
+    *target_memkb = (uint32_t) info.target_memkb;
+    rc = 0;
+
+out:
+    if (!xs_transaction_end(ctx->xsh, t, 0))
+        if (errno == EAGAIN)
+            goto retry_transaction;
+
+
+    return rc;
+}
+
 int libxl_set_memory_target(libxl_ctx *ctx, uint32_t domid, uint32_t target_memkb, int enforce)
 {
     libxl_gc gc = LIBXL_INIT_GC(ctx);
-    int rc = 1;
-    uint32_t memorykb = 0, videoram = 0;
-    char *memmax, *endptr, *videoram_s = NULL;
+    int rc = 1, abort = 0;
+    uint32_t videoram = 0;
+    char *videoram_s = NULL;
     char *dompath = libxl_xs_get_dompath(&gc, domid);
     xc_domaininfo_t info;
     libxl_dominfo ptr;
     char *uuid;
-
-    if (domid) {
-        memmax = libxl_xs_read(&gc, XBT_NULL, libxl_sprintf(&gc, "%s/memory/static-max", dompath));
-        if (!memmax) {
+    xs_transaction_t t;
+
+retry_transaction:
+    t = xs_transaction_start(ctx->xsh);
+
+    videoram_s = libxl_xs_read(&gc, t, libxl_sprintf(&gc, "%s/memory/videoram", dompath));
+    videoram = videoram_s ? atoi(videoram_s) : 0;
+
+    if (enforce) {
+        rc = xc_domain_setmaxmem(ctx->xch, domid, target_memkb + LIBXL_MAXMEM_CONSTANT);
+        if (rc != 0) {
             XL_LOG_ERRNO(ctx, XL_LOG_ERROR,
-                "cannot get memory info from %s/memory/static-max\n", dompath);
+                    "xc_domain_setmaxmem domid=%d memkb=%d failed "
+                    "rc=%d\n", domid, target_memkb + LIBXL_MAXMEM_CONSTANT, rc);
+            abort = 1;
             goto out;
         }
-        memorykb = strtoul(memmax, &endptr, 10);
+        libxl_xs_write(&gc, t, libxl_sprintf(&gc, "%s/memory/static-max", dompath), "%"PRIu32, target_memkb);
+    }
+
+    rc = xc_domain_memory_set_pod_target(ctx->xch, domid, (target_memkb - videoram) / 4, NULL, NULL, NULL);
+    if (rc != 0) {
+        XL_LOG_ERRNO(ctx, XL_LOG_ERROR,
+                "xc_domain_memory_set_pod_target domid=%d, memkb=%d "
+                "failed rc=%d\n", domid, (target_memkb - videoram) / 4,
+                rc);
+        abort = 1;
+        goto out;
+    }
+
+    libxl_xs_write(&gc, t, libxl_sprintf(&gc, "%s/memory/target", dompath), "%"PRIu32, target_memkb);
+    rc = xc_domain_getinfolist(ctx->xch, domid, 1, &info);
+    if (rc != 1 || info.domain != domid) {
+        abort = 1;
+        goto out;
+    }
+    xcinfo2xlinfo(&info, &ptr);
+    uuid = libxl_uuid2string(&gc, ptr.uuid);
+    libxl_xs_write(&gc, t, libxl_sprintf(&gc, "/vm/%s/memory", uuid), "%"PRIu32, target_memkb / 1024);
+
+out:
+    if (!xs_transaction_end(ctx->xsh, t, abort) && !abort)
+        if (errno == EAGAIN)
+            goto retry_transaction;
+
+    libxl_free_all(&gc);
+    return rc;
+}
+
+int libxl_set_relative_memory_target(libxl_ctx *ctx, uint32_t domid, int32_t relative_target_memkb, int enforce)
+{
+    libxl_gc gc = LIBXL_INIT_GC(ctx);
+    int rc = 1, abort = 0;
+    uint32_t memorykb = 0, videoram = 0, target_memkb = 0, new_target_memkb = 0;
+    char *memmax, *endptr, *videoram_s = NULL, *target = NULL;
+    char *dompath = libxl_xs_get_dompath(&gc, domid);
+    xc_domaininfo_t info;
+    libxl_dominfo ptr;
+    char *uuid;
+    xs_transaction_t t;
+
+retry_transaction:
+    t = xs_transaction_start(ctx->xsh);
+
+    target = libxl_xs_read(&gc, t, libxl_sprintf(&gc, "%s/memory/target", dompath));
+    if (!target && !domid) {
+        xs_transaction_end(ctx->xsh, t, 1);
+        rc = fill_dom0_memory_info(&gc, &target_memkb);
+        if (rc < 0) {
+            abort = 1;
+            goto out;
+        }
+        goto retry_transaction;
+    } else if (!target) {
+        XL_LOG_ERRNO(ctx, XL_LOG_ERROR,
+                "cannot get target memory info from %s/memory/target\n", dompath);
+        abort = 1;
+        goto out;
+    } else {
+        target_memkb = strtoul(target, &endptr, 10);
         if (*endptr != '\0') {
             XL_LOG_ERRNO(ctx, XL_LOG_ERROR,
-                "invalid max memory %s from %s/memory/static-max\n", memmax, dompath);
-            goto out;
-        }
-
-        if (target_memkb > memorykb) {
-            XL_LOG(ctx, XL_LOG_ERROR,
-                "memory_dynamic_max must be less than or equal to memory_static_max\n");
+                    "invalid memory target %s from %s/memory/target\n", target, dompath);
+            abort = 1;
             goto out;
         }
     }
-
-    videoram_s = libxl_xs_read(&gc, XBT_NULL, libxl_sprintf(&gc, "%s/memory/videoram", dompath));
+    memmax = libxl_xs_read(&gc, t, libxl_sprintf(&gc, "%s/memory/static-max", dompath));
+    if (!memmax) {
+        XL_LOG_ERRNO(ctx, XL_LOG_ERROR,
+                "cannot get memory info from %s/memory/static-max\n", dompath);
+        abort = 1;
+        goto out;
+    }
+    memorykb = strtoul(memmax, &endptr, 10);
+    if (*endptr != '\0') {
+        XL_LOG_ERRNO(ctx, XL_LOG_ERROR,
+                "invalid max memory %s from %s/memory/static-max\n", memmax, dompath);
+        abort = 1;
+        goto out;
+    }
+
+    new_target_memkb = target_memkb + relative_target_memkb;
+    if (new_target_memkb > memorykb) {
+        XL_LOG(ctx, XL_LOG_ERROR,
+                "memory_dynamic_max must be less than or equal to memory_static_max\n");
+        abort = 1;
+        goto out;
+    }
+
+    videoram_s = libxl_xs_read(&gc, t, libxl_sprintf(&gc, "%s/memory/videoram", dompath));
     videoram = videoram_s ? atoi(videoram_s) : 0;
 
-    libxl_xs_write(&gc, XBT_NULL, libxl_sprintf(&gc, "%s/memory/target", dompath), "%"PRIu32, target_memkb);
-
+    if (enforce) {
+        memorykb = new_target_memkb;
+        rc = xc_domain_setmaxmem(ctx->xch, domid, memorykb + LIBXL_MAXMEM_CONSTANT);
+        if (rc != 0) {
+            XL_LOG_ERRNO(ctx, XL_LOG_ERROR,
+                    "xc_domain_setmaxmem domid=%d memkb=%d failed "
+                    "rc=%d\n", domid, memorykb + LIBXL_MAXMEM_CONSTANT, rc);
+            abort = 1;
+            goto out;
+        }
+        libxl_xs_write(&gc, t, libxl_sprintf(&gc, "%s/memory/static-max", dompath), "%"PRIu32, memorykb);
+    }
+
+    rc = xc_domain_memory_set_pod_target(ctx->xch, domid, (new_target_memkb - videoram) / 4, NULL, NULL, NULL);
+    if (rc != 0) {
+        XL_LOG_ERRNO(ctx, XL_LOG_ERROR,
+                "xc_domain_memory_set_pod_target domid=%d, memkb=%d "
+                "failed rc=%d\n", domid, (new_target_memkb - videoram) / 4,
+                rc);
+        abort = 1;
+        goto out;
+    }
+
+    libxl_xs_write(&gc, t, libxl_sprintf(&gc, "%s/memory/target", dompath), "%"PRIu32, new_target_memkb);
     rc = xc_domain_getinfolist(ctx->xch, domid, 1, &info);
-    if (rc != 1 || info.domain != domid)
+    if (rc != 1 || info.domain != domid) {
+        abort = 1;
         goto out;
+    }
     xcinfo2xlinfo(&info, &ptr);
     uuid = libxl_uuid2string(&gc, ptr.uuid);
-    libxl_xs_write(&gc, XBT_NULL, libxl_sprintf(&gc, "/vm/%s/memory", uuid), "%"PRIu32, target_memkb / 1024);
-
-    if (enforce || !domid)
-        memorykb = target_memkb;
-    rc = xc_domain_setmaxmem(ctx->xch, domid, memorykb + LIBXL_MAXMEM_CONSTANT);
-    if (rc != 0)
+    libxl_xs_write(&gc, t, libxl_sprintf(&gc, "/vm/%s/memory", uuid), "%"PRIu32, new_target_memkb / 1024);
+
+out:
+    if (!xs_transaction_end(ctx->xsh, t, abort) && !abort)
+        if (errno == EAGAIN)
+            goto retry_transaction;
+
+    libxl_free_all(&gc);
+    return rc;
+}
+
+int libxl_get_memory_target(libxl_ctx *ctx, uint32_t domid, uint32_t *out_target)
+{
+    libxl_gc gc = LIBXL_INIT_GC(ctx);
+    int rc = 1;
+    char *target = NULL, *endptr = NULL;
+    char *dompath = libxl_xs_get_dompath(&gc, domid);
+    uint32_t target_memkb;
+
+    target = libxl_xs_read(&gc, XBT_NULL, libxl_sprintf(&gc, "%s/memory/target", dompath));
+    if (!target && !domid) {
+        rc = fill_dom0_memory_info(&gc, &target_memkb);
+        if (rc < 0)
+            goto out;
+    } else if (!target) {
+        XL_LOG_ERRNO(ctx, XL_LOG_ERROR,
+                "cannot get target memory info from %s/memory/target\n", dompath);
         goto out;
-    rc = xc_domain_memory_set_pod_target(ctx->xch, domid, (target_memkb - videoram) / 4, NULL, NULL, NULL);
+    } else {
+        target_memkb = strtoul(target, &endptr, 10);
+        if (*endptr != '\0') {
+            XL_LOG_ERRNO(ctx, XL_LOG_ERROR,
+                    "invalid memory target %s from %s/memory/target\n", target, dompath);
+            goto out;
+        }
+    }
+    *out_target = target_memkb;
+    rc = 0;
 
 out:
     libxl_free_all(&gc);
diff -r 990ff10b7b00 tools/libxl/libxl.h
--- a/tools/libxl/libxl.h	Wed Aug 25 20:59:35 2010 +0100
+++ b/tools/libxl/libxl.h	Wed Aug 25 21:01:36 2010 +0100
@@ -322,6 +322,8 @@ int libxl_domain_core_dump(libxl_ctx *ct
 
 int libxl_domain_setmaxmem(libxl_ctx *ctx, uint32_t domid, uint32_t target_memkb);
 int libxl_set_memory_target(libxl_ctx *ctx, uint32_t domid, uint32_t target_memkb, int enforce);
+int libxl_set_relative_memory_target(libxl_ctx *ctx, uint32_t domid, int32_t relative_target_memkb, int enforce);
+int libxl_get_memory_target(libxl_ctx *ctx, uint32_t domid, uint32_t *out_target);
 
 int libxl_vncviewer_exec(libxl_ctx *ctx, uint32_t domid, int autopass);
 int libxl_console_exec(libxl_ctx *ctx, uint32_t domid, int cons_num, libxl_console_constype type);