cluster/afr: Disable eager-lock if open-fd-count > 1

Lets say mount1 has eager-lock(full-lock) and after the eager-lock
is taken mount2 opened the same file, it won't be able to
perform any data operations until mount1 releases eager-lock.
To avoid such scenario do not enable eager-lock for transaction
if open-fd-count is > 1. Delaying of changelog piggybacking is
avoided in this situation.

Change-Id: I51b45d6a7c216a78860aff0265a0b8dabc6423a5
BUG: 910217
Signed-off-by: Pranith Kumar K <pkarampu@redhat.com>
Reviewed-on: http://review.gluster.org/5432
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: venkatesh somyajulu <vsomyaju@redhat.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

4 files changed, 98 insertions, 5 deletions

diff --git a/xlators/cluster/afr/src/afr-common.c b/xlators/cluster/afr/src/afr-common.c
index 075f33c618b..79644b74086 100644
--- a/xlators/cluster/afr/src/afr-common.c
+++ b/xlators/cluster/afr/src/afr-common.c
@@ -4890,3 +4890,28 @@ afr_is_fd_fixable (fd_t *fd)
 
         return _gf_true;
 }
+
+void
+afr_handle_open_fd_count (call_frame_t *frame, xlator_t *this)
+{
+        afr_local_t     *local = NULL;
+        inode_t         *inode = NULL;
+        afr_inode_ctx_t *ctx   = NULL;
+
+        local = frame->local;
+
+        if (local->fd)
+                inode = local->fd->inode;
+        else
+                inode = local->loc.inode;
+
+        if (!inode)
+                return;
+
+        LOCK (&inode->lock);
+        {
+                ctx = __afr_inode_ctx_get (inode, this);
+                ctx->open_fd_count = local->open_fd_count;
+        }
+        UNLOCK (&inode->lock);
+}
diff --git a/xlators/cluster/afr/src/afr-inode-write.c b/xlators/cluster/afr/src/afr-inode-write.c
index ce4fbf22698..68570f15afe 100644
--- a/xlators/cluster/afr/src/afr-inode-write.c
+++ b/xlators/cluster/afr/src/afr-inode-write.c
@@ -137,6 +137,8 @@ afr_writev_wind_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
         int child_index = (long) cookie;
         int call_count  = -1;
         int read_child  = 0;
+        int      ret = 0;
+        uint32_t open_fd_count = 0;
 
         local = frame->local;
 
@@ -162,6 +164,17 @@ afr_writev_wind_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
 		}
 
 		if (op_ret != -1) {
+                        if (xdata) {
+                                ret = dict_get_uint32 (xdata,
+                                                       GLUSTERFS_OPEN_FD_COUNT,
+                                                       &open_fd_count);
+                                if ((ret == 0) &&
+                                    (open_fd_count > local->open_fd_count)) {
+                                        local->open_fd_count = open_fd_count;
+                                        local->update_open_fd_count = _gf_true;
+                                }
+                        }
+
 			if ((local->success_count == 0) ||
 			    (child_index == read_child)) {
 				local->cont.writev.prebuf  = *prebuf;
@@ -176,8 +189,11 @@ afr_writev_wind_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
 
         if (call_count == 0) {
 
-		if (!local->stable_write)
-			afr_fd_report_unstable_write (this, local->fd);
+                if (local->update_open_fd_count)
+                        afr_handle_open_fd_count (frame, this);
+
+                if (!local->stable_write)
+                        afr_fd_report_unstable_write (this, local->fd);
 
                 afr_writev_handle_short_writes (frame, this);
                 /*
@@ -206,6 +222,8 @@ afr_writev_wind (call_frame_t *frame, xlator_t *this)
         afr_private_t *priv = NULL;
         int i = 0;
         int call_count = -1;
+        dict_t *xdata = NULL;
+        GF_UNUSED int     ret = 0;
 
         local = frame->local;
         priv = this->private;
@@ -229,6 +247,12 @@ afr_writev_wind (call_frame_t *frame, xlator_t *this)
 		return 0;
 	}
 
+        xdata = dict_new ();
+        if (xdata) {
+                ret = dict_set_uint32 (xdata, GLUSTERFS_OPEN_FD_COUNT,
+                                       sizeof (uint32_t));
+        }
+
         for (i = 0; i < priv->child_count; i++) {
                 if (local->transaction.pre_op[i]) {
                         STACK_WIND_COOKIE (frame, afr_writev_wind_cbk,
@@ -241,13 +265,16 @@ afr_writev_wind (call_frame_t *frame, xlator_t *this)
                                            local->cont.writev.offset,
                                            local->cont.writev.flags,
                                            local->cont.writev.iobref,
-                                           NULL);
+                                           xdata);
 
                         if (!--call_count)
                                 break;
                 }
         }
 
+        if (xdata)
+                dict_unref (xdata);
+
         return 0;
 }
 
diff --git a/xlators/cluster/afr/src/afr-transaction.c b/xlators/cluster/afr/src/afr-transaction.c
index def00e28834..817645505c6 100644
--- a/xlators/cluster/afr/src/afr-transaction.c
+++ b/xlators/cluster/afr/src/afr-transaction.c
@@ -1308,6 +1308,34 @@ afr_set_delayed_post_op (call_frame_t *frame, xlator_t *this)
                 local->delayed_post_op = _gf_true;
 }
 
+gf_boolean_t
+afr_are_multiple_fds_opened (inode_t *inode, xlator_t *this)
+{
+        afr_inode_ctx_t *ictx = NULL;
+
+        if (!inode) {
+                /* If false is returned, it may keep on taking eager-lock
+                 * which may lead to starvation, so return true to avoid that.
+                 */
+                gf_log_callingfn (this->name, GF_LOG_ERROR, "Invalid inode");
+                return _gf_true;
+        }
+        /* Lets say mount1 has eager-lock(full-lock) and after the eager-lock
+         * is taken mount2 opened the same file, it won't be able to
+         * perform any data operations until mount1 releases eager-lock.
+         * To avoid such scenario do not enable eager-lock for this transaction
+         * if open-fd-count is > 1
+         */
+
+        ictx = afr_inode_ctx_get (inode, this);
+        if (!ictx)
+                return _gf_true;
+
+        if (ictx->open_fd_count > 1)
+                return _gf_true;
+
+        return _gf_false;
+}
 
 gf_boolean_t
 is_afr_delayed_changelog_post_op_needed (call_frame_t *frame, xlator_t *this)
@@ -1322,6 +1350,9 @@ is_afr_delayed_changelog_post_op_needed (call_frame_t *frame, xlator_t *this)
         if (!local->delayed_post_op)
                 goto out;
 
+        if (local->fd && afr_are_multiple_fds_opened (local->fd->inode, this))
+                goto out;
+
         res = _gf_true;
 out:
         return res;
@@ -1753,8 +1784,7 @@ afr_locals_overlap (afr_local_t *local1, afr_local_t *local2)
         return ((end1 >= start2) && (end2 >= start1));
 }
 
-
-        void
+void
 afr_transaction_eager_lock_init (afr_local_t *local, xlator_t *this)
 {
         afr_private_t *priv = NULL;
@@ -1776,6 +1806,8 @@ afr_transaction_eager_lock_init (afr_local_t *local, xlator_t *this)
         if (!fdctx)
                 return;
 
+        if (afr_are_multiple_fds_opened (local->fd->inode, this))
+                return;
         /*
          * Once full file lock is acquired in eager-lock phase, overlapping
          * writes do not compete for inode-locks, instead are transferred to the
diff --git a/xlators/cluster/afr/src/afr.h b/xlators/cluster/afr/src/afr.h
index c6e6913df29..49d281acae1 100644
--- a/xlators/cluster/afr/src/afr.h
+++ b/xlators/cluster/afr/src/afr.h
@@ -87,6 +87,7 @@ typedef struct afr_inode_ctx_ {
         int32_t  *fresh_children;//increasing order of latency
         afr_spb_state_t mdata_spb;
         afr_spb_state_t data_spb;
+        uint32_t        open_fd_count;
 } afr_inode_ctx_t;
 
 typedef enum {
@@ -445,6 +446,8 @@ typedef struct _afr_local {
         unsigned int call_count;
         unsigned int success_count;
         unsigned int enoent_count;
+        uint32_t     open_fd_count;
+        gf_boolean_t update_open_fd_count;
 
 
         unsigned int unhealable;
@@ -1171,4 +1174,10 @@ afr_delayed_changelog_wake_resume (xlator_t *this, fd_t *fd, call_stub_t *stub);
 int
 afr_inodelk_init (afr_inodelk_t *lk, char *dom, size_t child_count);
 
+void
+afr_handle_open_fd_count (call_frame_t *frame, xlator_t *this);
+
+afr_inode_ctx_t*
+afr_inode_ctx_get (inode_t *inode, xlator_t *this);
+
 #endif /* __AFR_H__ */