glusterfs: discard (hole punch) support

Add support for the DISCARD file operation. Discard punches a hole
in a file in the provided range. Block de-allocation is implemented
via fallocate() (as requested via fuse and passed on to the brick
fs) but a separate fop is created within gluster to emphasize the
fact that discard changes file data (the discarded region is
replaced with zeroes) and must invalidate caches where appropriate.

BUG: 963678
Change-Id: I34633a0bfff2187afeab4292a15f3cc9adf261af
Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-on: http://review.gluster.org/5090
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>

10 files changed, 173 insertions, 0 deletions

diff --git a/libglusterfs/src/call-stub.c b/libglusterfs/src/call-stub.c
index 2bb993411b8..2f07a0074c5 100644
--- a/libglusterfs/src/call-stub.c
+++ b/libglusterfs/src/call-stub.c
@@ -2186,6 +2186,61 @@ out:
 
 }
 
+call_stub_t *
+fop_discard_cbk_stub(call_frame_t *frame, fop_discard_cbk_t fn,
+                     int32_t op_ret, int32_t op_errno,
+                     struct iatt *statpre, struct iatt *statpost,
+		     dict_t *xdata)
+{
+        call_stub_t *stub = NULL;
+
+        GF_VALIDATE_OR_GOTO ("call-stub", frame, out);
+
+        stub = stub_new (frame, 0, GF_FOP_DISCARD);
+        GF_VALIDATE_OR_GOTO ("call-stub", stub, out);
+
+        stub->fn_cbk.discard = fn;
+
+        stub->args_cbk.op_ret = op_ret;
+        stub->args_cbk.op_errno = op_errno;
+
+        if (statpre)
+                stub->args_cbk.prestat = *statpre;
+        if (statpost)
+                stub->args_cbk.poststat = *statpost;
+        if (xdata)
+                stub->args_cbk.xdata = dict_ref (xdata);
+out:
+        return stub;
+}
+
+call_stub_t *
+fop_discard_stub(call_frame_t *frame, fop_discard_t fn, fd_t *fd,
+		 off_t offset, size_t len, dict_t *xdata)
+{
+        call_stub_t *stub = NULL;
+
+        GF_VALIDATE_OR_GOTO ("call-stub", frame, out);
+        GF_VALIDATE_OR_GOTO ("call-stub", fn, out);
+
+        stub = stub_new (frame, 1, GF_FOP_DISCARD);
+        GF_VALIDATE_OR_GOTO ("call-stub", stub, out);
+
+        stub->fn.discard = fn;
+
+        if (fd)
+                stub->args.fd = fd_ref (fd);
+
+	stub->args.offset = offset;
+	stub->args.size = len;
+
+        if (xdata)
+                stub->args.xdata = dict_ref (xdata);
+out:
+        return stub;
+
+}
+
 static void
 call_resume_wind (call_stub_t *stub)
 {
@@ -2408,6 +2463,11 @@ call_resume_wind (call_stub_t *stub)
 				   stub->args.offset, stub->args.size,
 				   stub->args.xdata);
 		break;
+	case GF_FOP_DISCARD:
+		stub->fn.discard(stub->frame, stub->frame->this,
+				 stub->args.fd, stub->args.offset,
+				 stub->args.size, stub->args.xdata);
+		break;
         default:
                 gf_log_callingfn ("call-stub", GF_LOG_ERROR,
                                   "Invalid value of FOP (%d)",
@@ -2606,6 +2666,10 @@ call_resume_unwind (call_stub_t *stub)
 		STUB_UNWIND(stub, fallocate, &stub->args_cbk.prestat,
 			    &stub->args_cbk.poststat, stub->args_cbk.xdata);
 		break;
+	case GF_FOP_DISCARD:
+		STUB_UNWIND(stub, discard, &stub->args_cbk.prestat,
+			    &stub->args_cbk.poststat, stub->args_cbk.xdata);
+		break;
         default:
                 gf_log_callingfn ("call-stub", GF_LOG_ERROR,
                                   "Invalid value of FOP (%d)",
diff --git a/libglusterfs/src/call-stub.h b/libglusterfs/src/call-stub.h
index d940fe6f173..f0872b1219a 100644
--- a/libglusterfs/src/call-stub.h
+++ b/libglusterfs/src/call-stub.h
@@ -70,6 +70,7 @@ typedef struct {
 		fop_setattr_t setattr;
 		fop_fsetattr_t fsetattr;
 		fop_fallocate_t fallocate;
+		fop_discard_t discard;
 	} fn;
 
 	union {
@@ -115,6 +116,7 @@ typedef struct {
 		fop_setattr_cbk_t setattr;
 		fop_fsetattr_cbk_t fsetattr;
 		fop_fallocate_cbk_t fallocate;
+		fop_discard_cbk_t discard;
 	} fn_cbk;
 
 	struct {
@@ -729,6 +731,20 @@ fop_fallocate_cbk_stub(call_frame_t *frame,
                        struct iatt *statpre, struct iatt *statpost,
                        dict_t *xdata);
 
+call_stub_t *
+fop_discard_stub(call_frame_t *frame,
+		 fop_discard_t fn,
+		 fd_t *fd,
+		 off_t offset,
+		 size_t len, dict_t *xdata);
+
+call_stub_t *
+fop_discard_cbk_stub(call_frame_t *frame,
+		     fop_discard_cbk_t fn,
+                     int32_t op_ret, int32_t op_errno,
+                     struct iatt *statpre, struct iatt *statpost,
+                     dict_t *xdata);
+
 void call_resume (call_stub_t *stub);
 void call_stub_destroy (call_stub_t *stub);
 void call_unwind_error (call_stub_t *stub, int op_ret, int op_errno);
diff --git a/libglusterfs/src/defaults.c b/libglusterfs/src/defaults.c
index 32454a1e916..a3c8d97f112 100644
--- a/libglusterfs/src/defaults.c
+++ b/libglusterfs/src/defaults.c
@@ -464,6 +464,15 @@ default_fallocate_cbk(call_frame_t *frame, void *cookie, xlator_t *this,
 }
 
 int32_t
+default_discard_cbk(call_frame_t *frame, void *cookie, xlator_t *this,
+                    int32_t op_ret, int32_t op_errno, struct iatt *pre,
+                    struct iatt *post, dict_t *xdata)
+{
+	STACK_UNWIND_STRICT(discard, frame, op_ret, op_errno, pre, post, xdata);
+	return 0;
+}
+
+int32_t
 default_getspec_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
                      int32_t op_ret, int32_t op_errno, char *spec_data)
 {
@@ -881,6 +890,15 @@ default_fallocate_resume(call_frame_t *frame, xlator_t *this, fd_t *fd,
         return 0;
 }
 
+int32_t
+default_discard_resume(call_frame_t *frame, xlator_t *this, fd_t *fd,
+		       off_t offset, size_t len, dict_t *xdata)
+{
+	STACK_WIND(frame, default_discard_cbk, FIRST_CHILD(this),
+		   FIRST_CHILD(this)->fops->discard, fd, offset, len,
+		   xdata);
+        return 0;
+}
 
 /* FOPS */
 
@@ -1297,6 +1315,16 @@ default_fallocate(call_frame_t *frame, xlator_t *this, fd_t *fd,
 }
 
 int32_t
+default_discard(call_frame_t *frame, xlator_t *this, fd_t *fd,
+		off_t offset, size_t len, dict_t *xdata)
+{
+	STACK_WIND_TAIL(frame, FIRST_CHILD(this),
+			FIRST_CHILD(this)->fops->discard, fd, offset, len,
+			xdata);
+	return 0;
+}
+
+int32_t
 default_forget (xlator_t *this, inode_t *inode)
 {
         gf_log_callingfn (this->name, GF_LOG_WARNING, "xlator does not "
diff --git a/libglusterfs/src/defaults.h b/libglusterfs/src/defaults.h
index bc2f6429b09..f3cbb3a4bb7 100644
--- a/libglusterfs/src/defaults.h
+++ b/libglusterfs/src/defaults.h
@@ -249,6 +249,12 @@ int32_t default_fallocate(call_frame_t *frame,
 			  int32_t keep_size, off_t offset,
 			  size_t len, dict_t *xdata);
 
+int32_t default_discard(call_frame_t *frame,
+			xlator_t *this,
+			fd_t *fd,
+			off_t offset,
+			size_t len, dict_t *xdata);
+
 /* Resume */
 int32_t default_getspec_resume (call_frame_t *frame,
                                 xlator_t *this,
@@ -465,6 +471,11 @@ int32_t default_fallocate_resume(call_frame_t *frame,
 				 int32_t keep_size, off_t offset,
 				 size_t len, dict_t *xdata);
 
+int32_t default_discard_resume(call_frame_t *frame,
+			       xlator_t *this,
+			       fd_t *fd,
+			       off_t offset,
+			       size_t len, dict_t *xdata);
 
 /* _cbk */
 
@@ -680,6 +691,9 @@ int32_t default_fallocate_cbk(call_frame_t *frame, void *cookie, xlator_t *this,
 			      int32_t op_ret, int32_t op_errno, struct iatt *pre,
 			      struct iatt *post, dict_t *xdata);
 
+int32_t default_discard_cbk(call_frame_t *frame, void *cookie, xlator_t *this,
+			    int32_t op_ret, int32_t op_errno, struct iatt *pre,
+			    struct iatt *post, dict_t *xdata);
 
 int32_t
 default_getspec_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
diff --git a/libglusterfs/src/globals.c b/libglusterfs/src/globals.c
index ba5075b2eea..072b1d523f9 100644
--- a/libglusterfs/src/globals.c
+++ b/libglusterfs/src/globals.c
@@ -68,6 +68,7 @@ const char *gf_fop_list[GF_FOP_MAXVALUE] = {
         [GF_FOP_RELEASEDIR]  = "RELEASEDIR",
         [GF_FOP_FREMOVEXATTR]= "FREMOVEXATTR",
 	[GF_FOP_FALLOCATE]   = "FALLOCATE",
+	[GF_FOP_DISCARD]     = "DISCARD",
 };
 /* THIS */
 
diff --git a/libglusterfs/src/glusterfs.h b/libglusterfs/src/glusterfs.h
index 013cdfffa25..c2fbf5ac48d 100644
--- a/libglusterfs/src/glusterfs.h
+++ b/libglusterfs/src/glusterfs.h
@@ -198,6 +198,7 @@ typedef enum {
         GF_FOP_GETSPEC,
         GF_FOP_FREMOVEXATTR,
 	GF_FOP_FALLOCATE,
+	GF_FOP_DISCARD,
         GF_FOP_MAXVALUE,
 } glusterfs_fop_t;
 
diff --git a/libglusterfs/src/syncop.c b/libglusterfs/src/syncop.c
index f57e8da5a72..9cceaf55c5c 100644
--- a/libglusterfs/src/syncop.c
+++ b/libglusterfs/src/syncop.c
@@ -1948,6 +1948,36 @@ syncop_fallocate(xlator_t *subvol, fd_t *fd, int32_t keep_size, off_t offset,
 
 
 int
+syncop_discard_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
+                    int op_ret, int op_errno, struct iatt *prebuf,
+                    struct iatt *postbuf, dict_t *xdata)
+{
+	struct syncargs *args = NULL;
+
+        args = cookie;
+
+        args->op_ret   = op_ret;
+        args->op_errno = op_errno;
+
+        __wake (args);
+
+	return 0;
+}
+
+int
+syncop_discard(xlator_t *subvol, fd_t *fd, off_t offset, size_t len)
+{
+        struct syncargs args = {0, };
+
+        SYNCOP (subvol, (&args), syncop_discard_cbk, subvol->fops->discard,
+                fd, offset, len, NULL);
+
+        errno = args.op_errno;
+        return args.op_ret;
+}
+
+
+int
 syncop_lk_cbk (call_frame_t *frame, void *cookie, xlator_t *this,
 	       int op_ret, int op_errno, struct gf_flock *flock,
 	       dict_t *xdata)
diff --git a/libglusterfs/src/syncop.h b/libglusterfs/src/syncop.h
index 59e62ad14a2..43e71c4f6f8 100644
--- a/libglusterfs/src/syncop.h
+++ b/libglusterfs/src/syncop.h
@@ -335,6 +335,7 @@ int syncop_fsyncdir (xlator_t *subvol, fd_t *fd, int datasync);
 int syncop_access (xlator_t *subvol, loc_t *loc, int32_t mask);
 int syncop_fallocate(xlator_t *subvol, fd_t *fd, int32_t keep_size, off_t offset,
 		     size_t len);
+int syncop_discard(xlator_t *subvol, fd_t *fd, off_t offset, size_t len);
 
 int syncop_rename (xlator_t *subvol, loc_t *oldloc, loc_t *newloc);
 
diff --git a/libglusterfs/src/xlator.c b/libglusterfs/src/xlator.c
index 1926240e858..b1c090c1e64 100644
--- a/libglusterfs/src/xlator.c
+++ b/libglusterfs/src/xlator.c
@@ -80,6 +80,7 @@ fill_defaults (xlator_t *xl)
         SET_DEFAULT_FOP (setattr);
         SET_DEFAULT_FOP (fsetattr);
 	SET_DEFAULT_FOP (fallocate);
+	SET_DEFAULT_FOP (discard);
 
         SET_DEFAULT_FOP (getspec);
 
diff --git a/libglusterfs/src/xlator.h b/libglusterfs/src/xlator.h
index ace73f2ed03..817eaddecfe 100644
--- a/libglusterfs/src/xlator.h
+++ b/libglusterfs/src/xlator.h
@@ -425,6 +425,14 @@ typedef int32_t (*fop_fallocate_cbk_t) (call_frame_t *frame,
                                         struct iatt *preop_stbuf,
                                         struct iatt *postop_stbuf, dict_t *xdata);
 
+typedef int32_t (*fop_discard_cbk_t) (call_frame_t *frame,
+                                      void *cookie,
+                                      xlator_t *this,
+                                      int32_t op_ret,
+                                      int32_t op_errno,
+                                      struct iatt *preop_stbuf,
+                                      struct iatt *postop_stbuf, dict_t *xdata);
+
 typedef int32_t (*fop_lookup_t) (call_frame_t *frame,
                                  xlator_t *this,
                                  loc_t *loc,
@@ -650,6 +658,13 @@ typedef int32_t (*fop_fallocate_t) (call_frame_t *frame,
 				    size_t len,
                                     dict_t *xdata);
 
+typedef int32_t (*fop_discard_t) (call_frame_t *frame,
+                                  xlator_t *this,
+                                  fd_t *fd,
+				  off_t offset,
+				  size_t len,
+                                  dict_t *xdata);
+
 struct xlator_fops {
         fop_lookup_t         lookup;
         fop_stat_t           stat;
@@ -694,6 +709,7 @@ struct xlator_fops {
         fop_fsetattr_t       fsetattr;
         fop_getspec_t        getspec;
 	fop_fallocate_t	     fallocate;
+	fop_discard_t	     discard;
 
         /* these entries are used for a typechecking hack in STACK_WIND _only_ */
         fop_lookup_cbk_t         lookup_cbk;
@@ -739,6 +755,7 @@ struct xlator_fops {
         fop_fsetattr_cbk_t       fsetattr_cbk;
         fop_getspec_cbk_t        getspec_cbk;
 	fop_fallocate_cbk_t	 fallocate_cbk;
+	fop_discard_cbk_t	 discard_cbk;
 };
 
 typedef int32_t (*cbk_forget_t) (xlator_t *this,