cluster/ec: Allow parallel writes in EC if possible

Problem:
Ec at the moment sends one modification fop after another, so if some of
the disks become slow, for a while then the wait time for the writes that
are waiting in the queue becomes really bad.

Fix:
Allow parallel writes when possible. For this we need to make 3 changes.
1) Each fop now has range parameters they will be updating.
2) Xattrop is changed to handle parallel xattrop requests where some
   would be modifying just dirty xattr.
3) Fops that refer to size now take locks and update the locks.

Fixes #251
Change-Id: Ibc3c15372f91bbd6fb617f0d99399b3149fa64b2
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>

1 files changed, 30 insertions, 21 deletions

diff --git a/xlators/cluster/ec/src/ec.c b/xlators/cluster/ec/src/ec.c
index c32f4ef21dd..856d60c00c9 100644
--- a/xlators/cluster/ec/src/ec.c
+++ b/xlators/cluster/ec/src/ec.c
@@ -295,6 +295,8 @@ reconfigure (xlator_t *this, dict_t *options)
 
         GF_OPTION_RECONF ("optimistic-change-log", ec->optimistic_changelog,
                           options, bool, failed);
+        GF_OPTION_RECONF ("parallel-writes", ec->parallel_writes,
+                          options, bool, failed);
         ret = 0;
         if (ec_assign_read_policy (ec, read_policy)) {
                 ret = -1;
@@ -665,6 +667,7 @@ init (xlator_t *this)
     GF_OPTION_INIT ("shd-max-threads", ec->shd.max_threads, uint32, failed);
     GF_OPTION_INIT ("shd-wait-qlength", ec->shd.wait_qlength, uint32, failed);
     GF_OPTION_INIT ("optimistic-change-log", ec->optimistic_changelog, bool, failed);
+    GF_OPTION_INIT ("parallel-writes", ec->parallel_writes, bool, failed);
 
     this->itable = inode_table_new (EC_SHD_INODE_LRU_LIMIT, this);
     if (!this->itable)
@@ -1466,28 +1469,34 @@ struct volume_options options[] =
                        "galois field computations."
     },
     { .key  = {"self-heal-window-size"},
-        .type = GF_OPTION_TYPE_INT,
-        .min  = 1,
-        .max  = 1024,
-        .default_value = "1",
-        .description = "Maximum number blocks(128KB) per file for which "
-                       "self-heal process would be applied simultaneously."
+      .type = GF_OPTION_TYPE_INT,
+      .min  = 1,
+      .max  = 1024,
+      .default_value = "1",
+      .description = "Maximum number blocks(128KB) per file for which "
+                     "self-heal process would be applied simultaneously."
     },
-    {   .key = {"optimistic-change-log"},
-        .type = GF_OPTION_TYPE_BOOL,
-        .default_value = "on",
-        .description =  "Set/Unset dirty flag for every update fop at the start"
-                        "of the fop. If OFF, this option impacts performance of"
-                        "entry  operations or metadata operations as it will"
-                        "set dirty flag at the start and unset it at the end of"
-                        "ALL update fop. If ON and all the bricks are good,"
-                        "dirty flag will be set at the start only for file fops"
-                        "For metadata and entry fops dirty flag will not be set"
-                        "at the start, if all the bricks are good. This does"
-                        "not impact performance for metadata operations and"
-                        "entry operation but has a very small window to miss"
-                        "marking entry as dirty in case it is required to be"
-                        "healed"
+    { .key = {"optimistic-change-log"},
+      .type = GF_OPTION_TYPE_BOOL,
+      .default_value = "on",
+      .description =  "Set/Unset dirty flag for every update fop at the start"
+                      "of the fop. If OFF, this option impacts performance of"
+                      "entry  operations or metadata operations as it will"
+                      "set dirty flag at the start and unset it at the end of"
+                      "ALL update fop. If ON and all the bricks are good,"
+                      "dirty flag will be set at the start only for file fops"
+                      "For metadata and entry fops dirty flag will not be set"
+                      "at the start, if all the bricks are good. This does"
+                      "not impact performance for metadata operations and"
+                      "entry operation but has a very small window to miss"
+                      "marking entry as dirty in case it is required to be"
+                      "healed"
+    },
+    { .key = {"parallel-writes"},
+      .type = GF_OPTION_TYPE_BOOL,
+      .default_value = "on",
+      .description = "This controls if writes can be wound in parallel as long"
+                     "as it doesn't modify same stripes"
     },
     { .key = {NULL} }
 };