md-cache: support negative xattr entries

Add support for negative xattr caching. For this, we need
to fetch xattrs in every opportunity (including readdirplus)
in order to treat missing key in cached dict as negative entry.

This is crucial to detect missing ACL xattrs in Samba workload.

Change-Id: I918a2ef4ab804724256f7546b15e808332ed518d
BUG: 953694
Signed-off-by: Anand Avati <avati@redhat.com>
Reviewed-on: http://review.gluster.org/5160
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

1 files changed, 31 insertions, 10 deletions

diff --git a/xlators/performance/md-cache/src/md-cache.c b/xlators/performance/md-cache/src/md-cache.c
index ed811514701..b761eaa871c 100644
--- a/xlators/performance/md-cache/src/md-cache.c
+++ b/xlators/performance/md-cache/src/md-cache.c
@@ -598,13 +598,15 @@ mdc_inode_xatt_get (xlator_t *this, inode_t *inode, dict_t **dict)
 
         LOCK (&mdc->lock);
         {
+                ret = 0;
+		/* Missing xattr only means no keys were there, i.e
+		   a negative cache for the "loaded" keys
+		*/
                 if (!mdc->xattr)
                         goto unlock;
 
                 if (dict)
                         *dict = dict_ref (mdc->xattr);
-
-                ret = 0;
         }
 unlock:
         UNLOCK (&mdc->lock);
@@ -647,7 +649,7 @@ is_mdc_key_satisfied (const char *key)
 		return 0;
 
 	for (mdc_key = mdc_keys[i].name; (mdc_key = mdc_keys[i].name); i++) {
-		if (!mdc_keys[i].check)
+		if (!mdc_keys[i].load)
 			continue;
 		if (strcmp (mdc_key, key) == 0)
 			return 1;
@@ -721,6 +723,7 @@ mdc_lookup (call_frame_t *frame, xlator_t *this, loc_t *loc,
         struct iatt  stbuf = {0, };
         struct iatt  postparent = {0, };
         dict_t      *xattr_rsp = NULL;
+        dict_t      *xattr_alloc = NULL;
         mdc_local_t *local = NULL;
 
 
@@ -752,6 +755,8 @@ mdc_lookup (call_frame_t *frame, xlator_t *this, loc_t *loc,
         return 0;
 
 uncached:
+	if (!xdata)
+		xdata = xattr_alloc = dict_new ();
 	if (xdata)
 		mdc_load_reqs (this, xdata);
 
@@ -760,7 +765,8 @@ uncached:
 
         if (xattr_rsp)
                 dict_unref (xattr_rsp);
-
+	if (xattr_alloc)
+		dict_unref (xattr_alloc);
         return 0;
 }
 
@@ -1666,6 +1672,7 @@ mdc_getxattr (call_frame_t *frame, xlator_t *this, loc_t *loc, const char *key,
               dict_t *xdata)
 {
         int           ret;
+	int           op_errno = ENODATA;
         mdc_local_t  *local = NULL;
 	dict_t       *xattr = NULL;
 
@@ -1682,10 +1689,12 @@ mdc_getxattr (call_frame_t *frame, xlator_t *this, loc_t *loc, const char *key,
 	if (ret != 0)
 		goto uncached;
 
-	if (!dict_get (xattr, (char *)key))
-		goto uncached;
+	if (!xattr || dict_get (xattr, (char *)key)) {
+		ret = -1;
+		op_errno = ENODATA;
+	}
 
-        MDC_STACK_UNWIND (getxattr, frame, 0, 0, xattr, xdata);
+        MDC_STACK_UNWIND (getxattr, frame, ret, op_errno, xattr, xdata);
 
         return 0;
 
@@ -1727,6 +1736,7 @@ mdc_fgetxattr (call_frame_t *frame, xlator_t *this, fd_t *fd, const char *key,
         int           ret;
         mdc_local_t  *local = NULL;
 	dict_t       *xattr = NULL;
+	int           op_errno = ENODATA;
 
         local = mdc_local_get (frame);
         if (!local)
@@ -1741,10 +1751,12 @@ mdc_fgetxattr (call_frame_t *frame, xlator_t *this, fd_t *fd, const char *key,
 	if (ret != 0)
 		goto uncached;
 
-	if (!dict_get (xattr, (char *)key))
-		goto uncached;
+	if (!xattr || dict_get (xattr, (char *)key)) {
+		ret = -1;
+		op_errno = ENODATA;
+	}
 
-        MDC_STACK_UNWIND (fgetxattr, frame, 0, 0, xattr, xdata);
+        MDC_STACK_UNWIND (fgetxattr, frame, ret, op_errno, xattr, xdata);
 
         return 0;
 
@@ -1782,9 +1794,18 @@ int
 mdc_readdirp (call_frame_t *frame, xlator_t *this, fd_t *fd,
 	      size_t size, off_t offset, dict_t *xdata)
 {
+	dict_t *xattr_alloc = NULL;
+
+	if (!xdata)
+		xdata = xattr_alloc = dict_new ();
+	if (xdata)
+		mdc_load_reqs (this, xdata);
+
 	STACK_WIND (frame, mdc_readdirp_cbk,
 		    FIRST_CHILD (this), FIRST_CHILD (this)->fops->readdirp,
 		    fd, size, offset, xdata);
+	if (xattr_alloc)
+		dict_unref (xattr_alloc);
 	return 0;
 }