Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client

Pull Ceph changes from Alex Elder:
 "This is a big pull.

  Most of it is culmination of Alex's work to implement RBD image
  layering, which is now complete (yay!).

  There is also some work from Yan to fix i_mutex behavior surrounding
  writes in cephfs, a sync write fix, a fix for RBD images that get
  resized while they are mapped, and a few patches from me that resolve
  annoying auth warnings and fix several bugs in the ceph auth code."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client: (254 commits)
  rbd: fix image request leak on parent read
  libceph: use slab cache for osd client requests
  libceph: allocate ceph message data with a slab allocator
  libceph: allocate ceph messages with a slab allocator
  rbd: allocate image object names with a slab allocator
  rbd: allocate object requests with a slab allocator
  rbd: allocate name separate from obj_request
  rbd: allocate image requests with a slab allocator
  rbd: use binary search for snapshot lookup
  rbd: clear EXISTS flag if mapped snapshot disappears
  rbd: kill off the snapshot list
  rbd: define rbd_snap_size() and rbd_snap_features()
  rbd: use snap_id not index to look up snap info
  rbd: look up snapshot name in names buffer
  rbd: drop obj_request->version
  rbd: drop rbd_obj_method_sync() version parameter
  rbd: more version parameter removal
  rbd: get rid of some version parameters
  rbd: stop tracking header object version
  rbd: snap names are pointer to constant data
  ...

1 files changed, 1834 insertions, 1024 deletions

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index b7b7a88d9f68..c2ca1818f335 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -1,3 +1,4 @@
+
 /*
    rbd.c -- Export ceph rados objects as a Linux block device
 
@@ -32,12 +33,14 @@
 #include <linux/ceph/mon_client.h>
 #include <linux/ceph/decode.h>
 #include <linux/parser.h>
+#include <linux/bsearch.h>
 
 #include <linux/kernel.h>
 #include <linux/device.h>
 #include <linux/module.h>
 #include <linux/fs.h>
 #include <linux/blkdev.h>
+#include <linux/slab.h>
 
 #include "rbd_types.h"
 
@@ -52,13 +55,6 @@
 #define	SECTOR_SHIFT	9
 #define	SECTOR_SIZE	(1ULL << SECTOR_SHIFT)
 
-/* It might be useful to have these defined elsewhere */
-
-#define	U8_MAX	((u8)	(~0U))
-#define	U16_MAX	((u16)	(~0U))
-#define	U32_MAX	((u32)	(~0U))
-#define	U64_MAX	((u64)	(~0ULL))
-
 #define RBD_DRV_NAME "rbd"
 #define RBD_DRV_NAME_LONG "rbd (rados block device)"
 
@@ -72,6 +68,8 @@
 
 #define RBD_SNAP_HEAD_NAME	"-"
 
+#define	BAD_SNAP_INDEX	U32_MAX		/* invalid index into snap array */
+
 /* This allows a single page to hold an image name sent by OSD */
 #define RBD_IMAGE_NAME_LEN_MAX	(PAGE_SIZE - sizeof (__le32) - 1)
 #define RBD_IMAGE_ID_LEN_MAX	64
@@ -80,11 +78,14 @@
 
 /* Feature bits */
 
-#define RBD_FEATURE_LAYERING      1
+#define RBD_FEATURE_LAYERING	(1<<0)
+#define RBD_FEATURE_STRIPINGV2	(1<<1)
+#define RBD_FEATURES_ALL \
+	    (RBD_FEATURE_LAYERING | RBD_FEATURE_STRIPINGV2)
 
 /* Features supported by this (client software) implementation. */
 
-#define RBD_FEATURES_ALL          (0)
+#define RBD_FEATURES_SUPPORTED	(RBD_FEATURES_ALL)
 
 /*
  * An RBD device name will be "rbd#", where the "rbd" comes from
@@ -112,7 +113,8 @@ struct rbd_image_header {
 	char *snap_names;
 	u64 *snap_sizes;
 
-	u64 obj_version;
+	u64 stripe_unit;
+	u64 stripe_count;
 };
 
 /*
@@ -142,13 +144,13 @@ struct rbd_image_header {
  */
 struct rbd_spec {
 	u64		pool_id;
-	char		*pool_name;
+	const char	*pool_name;
 
-	char		*image_id;
-	char		*image_name;
+	const char	*image_id;
+	const char	*image_name;
 
 	u64		snap_id;
-	char		*snap_name;
+	const char	*snap_name;
 
 	struct kref	kref;
 };
@@ -174,13 +176,44 @@ enum obj_request_type {
 	OBJ_REQUEST_NODATA, OBJ_REQUEST_BIO, OBJ_REQUEST_PAGES
 };
 
+enum obj_req_flags {
+	OBJ_REQ_DONE,		/* completion flag: not done = 0, done = 1 */
+	OBJ_REQ_IMG_DATA,	/* object usage: standalone = 0, image = 1 */
+	OBJ_REQ_KNOWN,		/* EXISTS flag valid: no = 0, yes = 1 */
+	OBJ_REQ_EXISTS,		/* target exists: no = 0, yes = 1 */
+};
+
 struct rbd_obj_request {
 	const char		*object_name;
 	u64			offset;		/* object start byte */
 	u64			length;		/* bytes from offset */
+	unsigned long		flags;
 
-	struct rbd_img_request	*img_request;
-	struct list_head	links;		/* img_request->obj_requests */
+	/*
+	 * An object request associated with an image will have its
+	 * img_data flag set; a standalone object request will not.
+	 *
+	 * A standalone object request will have which == BAD_WHICH
+	 * and a null obj_request pointer.
+	 *
+	 * An object request initiated in support of a layered image
+	 * object (to check for its existence before a write) will
+	 * have which == BAD_WHICH and a non-null obj_request pointer.
+	 *
+	 * Finally, an object request for rbd image data will have
+	 * which != BAD_WHICH, and will have a non-null img_request
+	 * pointer.  The value of which will be in the range
+	 * 0..(img_request->obj_request_count-1).
+	 */
+	union {
+		struct rbd_obj_request	*obj_request;	/* STAT op */
+		struct {
+			struct rbd_img_request	*img_request;
+			u64			img_offset;
+			/* links for img_request->obj_requests list */
+			struct list_head	links;
+		};
+	};
 	u32			which;		/* posn image request list */
 
 	enum obj_request_type	type;
@@ -191,13 +224,12 @@ struct rbd_obj_request {
 			u32		page_count;
 		};
 	};
+	struct page		**copyup_pages;
 
 	struct ceph_osd_request	*osd_req;
 
 	u64			xferred;	/* bytes transferred */
-	u64			version;
 	int			result;
-	atomic_t		done;
 
 	rbd_obj_callback_t	callback;
 	struct completion	completion;
@@ -205,19 +237,31 @@ struct rbd_obj_request {
 	struct kref		kref;
 };
 
+enum img_req_flags {
+	IMG_REQ_WRITE,		/* I/O direction: read = 0, write = 1 */
+	IMG_REQ_CHILD,		/* initiator: block = 0, child image = 1 */
+	IMG_REQ_LAYERED,	/* ENOENT handling: normal = 0, layered = 1 */
+};
+
 struct rbd_img_request {
-	struct request		*rq;
 	struct rbd_device	*rbd_dev;
 	u64			offset;	/* starting image byte offset */
 	u64			length;	/* byte count from offset */
-	bool			write_request;	/* false for read */
+	unsigned long		flags;
 	union {
+		u64			snap_id;	/* for reads */
 		struct ceph_snap_context *snapc;	/* for writes */
-		u64		snap_id;		/* for reads */
 	};
+	union {
+		struct request		*rq;		/* block request */
+		struct rbd_obj_request	*obj_request;	/* obj req initiator */
+	};
+	struct page		**copyup_pages;
 	spinlock_t		completion_lock;/* protects next_completion */
 	u32			next_completion;
 	rbd_img_callback_t	callback;
+	u64			xferred;/* aggregate bytes transferred */
+	int			result;	/* first nonzero obj_request result */
 
 	u32			obj_request_count;
 	struct list_head	obj_requests;	/* rbd_obj_request structs */
@@ -232,15 +276,6 @@ struct rbd_img_request {
 #define for_each_obj_request_safe(ireq, oreq, n) \
 	list_for_each_entry_safe_reverse(oreq, n, &(ireq)->obj_requests, links)
 
-struct rbd_snap {
-	struct	device		dev;
-	const char		*name;
-	u64			size;
-	struct list_head	node;
-	u64			id;
-	u64			features;
-};
-
 struct rbd_mapping {
 	u64                     size;
 	u64                     features;
@@ -276,6 +311,7 @@ struct rbd_device {
 
 	struct rbd_spec		*parent_spec;
 	u64			parent_overlap;
+	struct rbd_device	*parent;
 
 	/* protects updating the header */
 	struct rw_semaphore     header_rwsem;
@@ -284,9 +320,6 @@ struct rbd_device {
 
 	struct list_head	node;
 
-	/* list of snapshots */
-	struct list_head	snaps;
-
 	/* sysfs related */
 	struct device		dev;
 	unsigned long		open_count;	/* protected by lock */
@@ -312,16 +345,21 @@ static DEFINE_SPINLOCK(rbd_dev_list_lock);
 static LIST_HEAD(rbd_client_list);		/* clients */
 static DEFINE_SPINLOCK(rbd_client_list_lock);
 
-static int rbd_dev_snaps_update(struct rbd_device *rbd_dev);
-static int rbd_dev_snaps_register(struct rbd_device *rbd_dev);
+/* Slab caches for frequently-allocated structures */
+
+static struct kmem_cache	*rbd_img_request_cache;
+static struct kmem_cache	*rbd_obj_request_cache;
+static struct kmem_cache	*rbd_segment_name_cache;
 
-static void rbd_dev_release(struct device *dev);
-static void rbd_remove_snap_dev(struct rbd_snap *snap);
+static int rbd_img_request_submit(struct rbd_img_request *img_request);
+
+static void rbd_dev_device_release(struct device *dev);
 
 static ssize_t rbd_add(struct bus_type *bus, const char *buf,
 		       size_t count);
 static ssize_t rbd_remove(struct bus_type *bus, const char *buf,
 			  size_t count);
+static int rbd_dev_image_probe(struct rbd_device *rbd_dev);
 
 static struct bus_attribute rbd_bus_attrs[] = {
 	__ATTR(add, S_IWUSR, NULL, rbd_add),
@@ -383,8 +421,19 @@ void rbd_warn(struct rbd_device *rbd_dev, const char *fmt, ...)
 #  define rbd_assert(expr)	((void) 0)
 #endif /* !RBD_DEBUG */
 
-static int rbd_dev_refresh(struct rbd_device *rbd_dev, u64 *hver);
-static int rbd_dev_v2_refresh(struct rbd_device *rbd_dev, u64 *hver);
+static int rbd_img_obj_request_submit(struct rbd_obj_request *obj_request);
+static void rbd_img_parent_read(struct rbd_obj_request *obj_request);
+static void rbd_dev_remove_parent(struct rbd_device *rbd_dev);
+
+static int rbd_dev_refresh(struct rbd_device *rbd_dev);
+static int rbd_dev_v2_refresh(struct rbd_device *rbd_dev);
+static const char *rbd_dev_v2_snap_name(struct rbd_device *rbd_dev,
+					u64 snap_id);
+static int _rbd_dev_v2_snap_size(struct rbd_device *rbd_dev, u64 snap_id,
+				u8 *order, u64 *snap_size);
+static int _rbd_dev_v2_snap_features(struct rbd_device *rbd_dev, u64 snap_id,
+		u64 *snap_features);
+static u64 rbd_snap_id_by_name(struct rbd_device *rbd_dev, const char *name);
 
 static int rbd_open(struct block_device *bdev, fmode_t mode)
 {
@@ -484,6 +533,13 @@ out_opt:
 	return ERR_PTR(ret);
 }
 
+static struct rbd_client *__rbd_get_client(struct rbd_client *rbdc)
+{
+	kref_get(&rbdc->kref);
+
+	return rbdc;
+}
+
 /*
  * Find a ceph client with specific addr and configuration.  If
  * found, bump its reference count.
@@ -499,7 +555,8 @@ static struct rbd_client *rbd_client_find(struct ceph_options *ceph_opts)
 	spin_lock(&rbd_client_list_lock);
 	list_for_each_entry(client_node, &rbd_client_list, node) {
 		if (!ceph_compare_options(ceph_opts, client_node->client)) {
-			kref_get(&client_node->kref);
+			__rbd_get_client(client_node);
+
 			found = true;
 			break;
 		}
@@ -722,7 +779,6 @@ static int rbd_header_from_disk(struct rbd_image_header *header,
 			header->snap_sizes[i] =
 				le64_to_cpu(ondisk->snaps[i].image_size);
 	} else {
-		WARN_ON(ondisk->snap_names_len);
 		header->snap_names = NULL;
 		header->snap_sizes = NULL;
 	}
@@ -735,18 +791,13 @@ static int rbd_header_from_disk(struct rbd_image_header *header,
 	/* Allocate and fill in the snapshot context */
 
 	header->image_size = le64_to_cpu(ondisk->image_size);
-	size = sizeof (struct ceph_snap_context);
-	size += snap_count * sizeof (header->snapc->snaps[0]);
-	header->snapc = kzalloc(size, GFP_KERNEL);
+
+	header->snapc = ceph_create_snap_context(snap_count, GFP_KERNEL);
 	if (!header->snapc)
 		goto out_err;
-
-	atomic_set(&header->snapc->nref, 1);
 	header->snapc->seq = le64_to_cpu(ondisk->snap_seq);
-	header->snapc->num_snaps = snap_count;
 	for (i = 0; i < snap_count; i++)
-		header->snapc->snaps[i] =
-			le64_to_cpu(ondisk->snaps[i].id);
+		header->snapc->snaps[i] = le64_to_cpu(ondisk->snaps[i].id);
 
 	return 0;
 
@@ -761,70 +812,174 @@ out_err:
 	return -ENOMEM;
 }
 
-static const char *rbd_snap_name(struct rbd_device *rbd_dev, u64 snap_id)
+static const char *_rbd_dev_v1_snap_name(struct rbd_device *rbd_dev, u32 which)
 {
-	struct rbd_snap *snap;
+	const char *snap_name;
 
+	rbd_assert(which < rbd_dev->header.snapc->num_snaps);
+
+	/* Skip over names until we find the one we are looking for */
+
+	snap_name = rbd_dev->header.snap_names;
+	while (which--)
+		snap_name += strlen(snap_name) + 1;
+
+	return kstrdup(snap_name, GFP_KERNEL);
+}
+
+/*
+ * Snapshot id comparison function for use with qsort()/bsearch().
+ * Note that result is for snapshots in *descending* order.
+ */
+static int snapid_compare_reverse(const void *s1, const void *s2)
+{
+	u64 snap_id1 = *(u64 *)s1;
+	u64 snap_id2 = *(u64 *)s2;
+
+	if (snap_id1 < snap_id2)
+		return 1;
+	return snap_id1 == snap_id2 ? 0 : -1;
+}
+
+/*
+ * Search a snapshot context to see if the given snapshot id is
+ * present.
+ *
+ * Returns the position of the snapshot id in the array if it's found,
+ * or BAD_SNAP_INDEX otherwise.
+ *
+ * Note: The snapshot array is in kept sorted (by the osd) in
+ * reverse order, highest snapshot id first.
+ */
+static u32 rbd_dev_snap_index(struct rbd_device *rbd_dev, u64 snap_id)
+{
+	struct ceph_snap_context *snapc = rbd_dev->header.snapc;
+	u64 *found;
+
+	found = bsearch(&snap_id, &snapc->snaps, snapc->num_snaps,
+				sizeof (snap_id), snapid_compare_reverse);
+
+	return found ? (u32)(found - &snapc->snaps[0]) : BAD_SNAP_INDEX;
+}
+
+static const char *rbd_dev_v1_snap_name(struct rbd_device *rbd_dev,
+					u64 snap_id)
+{
+	u32 which;
+
+	which = rbd_dev_snap_index(rbd_dev, snap_id);
+	if (which == BAD_SNAP_INDEX)
+		return NULL;
+
+	return _rbd_dev_v1_snap_name(rbd_dev, which);
+}
+
+static const char *rbd_snap_name(struct rbd_device *rbd_dev, u64 snap_id)
+{
 	if (snap_id == CEPH_NOSNAP)
 		return RBD_SNAP_HEAD_NAME;
 
-	list_for_each_entry(snap, &rbd_dev->snaps, node)
-		if (snap_id == snap->id)
-			return snap->name;
+	rbd_assert(rbd_image_format_valid(rbd_dev->image_format));
+	if (rbd_dev->image_format == 1)
+		return rbd_dev_v1_snap_name(rbd_dev, snap_id);
 
-	return NULL;
+	return rbd_dev_v2_snap_name(rbd_dev, snap_id);
 }
 
-static int snap_by_name(struct rbd_device *rbd_dev, const char *snap_name)
+static int rbd_snap_size(struct rbd_device *rbd_dev, u64 snap_id,
+				u64 *snap_size)
 {
+	rbd_assert(rbd_image_format_valid(rbd_dev->image_format));
+	if (snap_id == CEPH_NOSNAP) {
+		*snap_size = rbd_dev->header.image_size;
+	} else if (rbd_dev->image_format == 1) {
+		u32 which;
 
-	struct rbd_snap *snap;
+		which = rbd_dev_snap_index(rbd_dev, snap_id);
+		if (which == BAD_SNAP_INDEX)
+			return -ENOENT;
 
-	list_for_each_entry(snap, &rbd_dev->snaps, node) {
-		if (!strcmp(snap_name, snap->name)) {
-			rbd_dev->spec->snap_id = snap->id;
-			rbd_dev->mapping.size = snap->size;
-			rbd_dev->mapping.features = snap->features;
+		*snap_size = rbd_dev->header.snap_sizes[which];
+	} else {
+		u64 size = 0;
+		int ret;
 
-			return 0;
-		}
+		ret = _rbd_dev_v2_snap_size(rbd_dev, snap_id, NULL, &size);
+		if (ret)
+			return ret;
+
+		*snap_size = size;
 	}
+	return 0;
+}
+
+static int rbd_snap_features(struct rbd_device *rbd_dev, u64 snap_id,
+			u64 *snap_features)
+{
+	rbd_assert(rbd_image_format_valid(rbd_dev->image_format));
+	if (snap_id == CEPH_NOSNAP) {
+		*snap_features = rbd_dev->header.features;
+	} else if (rbd_dev->image_format == 1) {
+		*snap_features = 0;	/* No features for format 1 */
+	} else {
+		u64 features = 0;
+		int ret;
+
+		ret = _rbd_dev_v2_snap_features(rbd_dev, snap_id, &features);
+		if (ret)
+			return ret;
 
-	return -ENOENT;
+		*snap_features = features;
+	}
+	return 0;
 }
 
-static int rbd_dev_set_mapping(struct rbd_device *rbd_dev)
+static int rbd_dev_mapping_set(struct rbd_device *rbd_dev)
 {
+	const char *snap_name = rbd_dev->spec->snap_name;
+	u64 snap_id;
+	u64 size = 0;
+	u64 features = 0;
 	int ret;
 
-	if (!memcmp(rbd_dev->spec->snap_name, RBD_SNAP_HEAD_NAME,
-		    sizeof (RBD_SNAP_HEAD_NAME))) {
-		rbd_dev->spec->snap_id = CEPH_NOSNAP;
-		rbd_dev->mapping.size = rbd_dev->header.image_size;
-		rbd_dev->mapping.features = rbd_dev->header.features;
-		ret = 0;
+	if (strcmp(snap_name, RBD_SNAP_HEAD_NAME)) {
+		snap_id = rbd_snap_id_by_name(rbd_dev, snap_name);
+		if (snap_id == CEPH_NOSNAP)
+			return -ENOENT;
 	} else {
-		ret = snap_by_name(rbd_dev, rbd_dev->spec->snap_name);
-		if (ret < 0)
-			goto done;
-		rbd_dev->mapping.read_only = true;
+		snap_id = CEPH_NOSNAP;
 	}
-	set_bit(RBD_DEV_FLAG_EXISTS, &rbd_dev->flags);
 
-done:
-	return ret;
+	ret = rbd_snap_size(rbd_dev, snap_id, &size);
+	if (ret)
+		return ret;
+	ret = rbd_snap_features(rbd_dev, snap_id, &features);
+	if (ret)
+		return ret;
+
+	rbd_dev->mapping.size = size;
+	rbd_dev->mapping.features = features;
+
+	/* If we are mapping a snapshot it must be marked read-only */
+
+	if (snap_id != CEPH_NOSNAP)
+		rbd_dev->mapping.read_only = true;
+
+	return 0;
 }
 
-static void rbd_header_free(struct rbd_image_header *header)
+static void rbd_dev_mapping_clear(struct rbd_device *rbd_dev)
 {
-	kfree(header->object_prefix);
-	header->object_prefix = NULL;
-	kfree(header->snap_sizes);
-	header->snap_sizes = NULL;
-	kfree(header->snap_names);
-	header->snap_names = NULL;
-	ceph_put_snap_context(header->snapc);
-	header->snapc = NULL;
+	rbd_dev->mapping.size = 0;
+	rbd_dev->mapping.features = 0;
+	rbd_dev->mapping.read_only = true;
+}
+
+static void rbd_dev_clear_mapping(struct rbd_device *rbd_dev)
+{
+	rbd_dev->mapping.size = 0;
+	rbd_dev->mapping.features = 0;
+	rbd_dev->mapping.read_only = true;
 }
 
 static const char *rbd_segment_name(struct rbd_device *rbd_dev, u64 offset)
@@ -833,7 +988,7 @@ static const char *rbd_segment_name(struct rbd_device *rbd_dev, u64 offset)
 	u64 segment;
 	int ret;
 
-	name = kmalloc(MAX_OBJ_NAME_SIZE + 1, GFP_NOIO);
+	name = kmem_cache_alloc(rbd_segment_name_cache, GFP_NOIO);
 	if (!name)
 		return NULL;
 	segment = offset >> rbd_dev->header.obj_order;
@@ -849,6 +1004,13 @@ static const char *rbd_segment_name(struct rbd_device *rbd_dev, u64 offset)
 	return name;
 }
 
+static void rbd_segment_name_free(const char *name)
+{
+	/* The explicit cast here is needed to drop the const qualifier */
+
+	kmem_cache_free(rbd_segment_name_cache, (void *)name);
+}
+
 static u64 rbd_segment_offset(struct rbd_device *rbd_dev, u64 offset)
 {
 	u64 segment_size = (u64) 1 << rbd_dev->header.obj_order;
@@ -921,6 +1083,37 @@ static void zero_bio_chain(struct bio *chain, int start_ofs)
 }
 
 /*
+ * similar to zero_bio_chain(), zeros data defined by a page array,
+ * starting at the given byte offset from the start of the array and
+ * continuing up to the given end offset.  The pages array is
+ * assumed to be big enough to hold all bytes up to the end.
+ */
+static void zero_pages(struct page **pages, u64 offset, u64 end)
+{
+	struct page **page = &pages[offset >> PAGE_SHIFT];
+
+	rbd_assert(end > offset);
+	rbd_assert(end - offset <= (u64)SIZE_MAX);
+	while (offset < end) {
+		size_t page_offset;
+		size_t length;
+		unsigned long flags;
+		void *kaddr;
+
+		page_offset = (size_t)(offset & ~PAGE_MASK);
+		length = min(PAGE_SIZE - page_offset, (size_t)(end - offset));
+		local_irq_save(flags);
+		kaddr = kmap_atomic(*page);
+		memset(kaddr + page_offset, 0, length);
+		kunmap_atomic(kaddr);
+		local_irq_restore(flags);
+
+		offset += length;
+		page++;
+	}
+}
+
+/*
  * Clone a portion of a bio, starting at the given byte offset
  * and continuing for the number of bytes indicated.
  */
@@ -1064,6 +1257,77 @@ out_err:
 	return NULL;
 }
 
+/*
+ * The default/initial value for all object request flags is 0.  For
+ * each flag, once its value is set to 1 it is never reset to 0
+ * again.
+ */
+static void obj_request_img_data_set(struct rbd_obj_request *obj_request)
+{
+	if (test_and_set_bit(OBJ_REQ_IMG_DATA, &obj_request->flags)) {
+		struct rbd_device *rbd_dev;
+
+		rbd_dev = obj_request->img_request->rbd_dev;
+		rbd_warn(rbd_dev, "obj_request %p already marked img_data\n",
+			obj_request);
+	}
+}
+
+static bool obj_request_img_data_test(struct rbd_obj_request *obj_request)
+{
+	smp_mb();
+	return test_bit(OBJ_REQ_IMG_DATA, &obj_request->flags) != 0;
+}
+
+static void obj_request_done_set(struct rbd_obj_request *obj_request)
+{
+	if (test_and_set_bit(OBJ_REQ_DONE, &obj_request->flags)) {
+		struct rbd_device *rbd_dev = NULL;
+
+		if (obj_request_img_data_test(obj_request))
+			rbd_dev = obj_request->img_request->rbd_dev;
+		rbd_warn(rbd_dev, "obj_request %p already marked done\n",
+			obj_request);
+	}
+}
+
+static bool obj_request_done_test(struct rbd_obj_request *obj_request)
+{
+	smp_mb();
+	return test_bit(OBJ_REQ_DONE, &obj_request->flags) != 0;
+}
+
+/*
+ * This sets the KNOWN flag after (possibly) setting the EXISTS
+ * flag.  The latter is set based on the "exists" value provided.
+ *
+ * Note that for our purposes once an object exists it never goes
+ * away again.  It's possible that the response from two existence
+ * checks are separated by the creation of the target object, and
+ * the first ("doesn't exist") response arrives *after* the second
+ * ("does exist").  In that case we ignore the second one.
+ */
+static void obj_request_existence_set(struct rbd_obj_request *obj_request,
+				bool exists)
+{
+	if (exists)
+		set_bit(OBJ_REQ_EXISTS, &obj_request->flags);
+	set_bit(OBJ_REQ_KNOWN, &obj_request->flags);
+	smp_mb();
+}
+
+static bool obj_request_known_test(struct rbd_obj_request *obj_request)
+{
+	smp_mb();
+	return test_bit(OBJ_REQ_KNOWN, &obj_request->flags) != 0;
+}
+
+static bool obj_request_exists_test(struct rbd_obj_request *obj_request)
+{
+	smp_mb();
+	return test_bit(OBJ_REQ_EXISTS, &obj_request->flags) != 0;
+}
+
 static void rbd_obj_request_get(struct rbd_obj_request *obj_request)
 {
 	dout("%s: obj %p (was %d)\n", __func__, obj_request,
@@ -1101,9 +1365,11 @@ static inline void rbd_img_obj_request_add(struct rbd_img_request *img_request,
 {
 	rbd_assert(obj_request->img_request == NULL);
 
-	rbd_obj_request_get(obj_request);
+	/* Image request now owns object's original reference */
 	obj_request->img_request = img_request;
 	obj_request->which = img_request->obj_request_count;
+	rbd_assert(!obj_request_img_data_test(obj_request));
+	obj_request_img_data_set(obj_request);
 	rbd_assert(obj_request->which != BAD_WHICH);
 	img_request->obj_request_count++;
 	list_add_tail(&obj_request->links, &img_request->obj_requests);
@@ -1123,6 +1389,7 @@ static inline void rbd_img_obj_request_del(struct rbd_img_request *img_request,
 	img_request->obj_request_count--;
 	rbd_assert(obj_request->which == img_request->obj_request_count);
 	obj_request->which = BAD_WHICH;
+	rbd_assert(obj_request_img_data_test(obj_request));
 	rbd_assert(obj_request->img_request == img_request);
 	obj_request->img_request = NULL;
 	obj_request->callback = NULL;
@@ -1141,76 +1408,6 @@ static bool obj_request_type_valid(enum obj_request_type type)
 	}
 }
 
-static struct ceph_osd_req_op *rbd_osd_req_op_create(u16 opcode, ...)
-{
-	struct ceph_osd_req_op *op;
-	va_list args;
-	size_t size;
-
-	op = kzalloc(sizeof (*op), GFP_NOIO);
-	if (!op)
-		return NULL;
-	op->op = opcode;
-	va_start(args, opcode);
-	switch (opcode) {
-	case CEPH_OSD_OP_READ:
-	case CEPH_OSD_OP_WRITE:
-		/* rbd_osd_req_op_create(READ, offset, length) */
-		/* rbd_osd_req_op_create(WRITE, offset, length) */
-		op->extent.offset = va_arg(args, u64);
-		op->extent.length = va_arg(args, u64);
-		if (opcode == CEPH_OSD_OP_WRITE)
-			op->payload_len = op->extent.length;
-		break;
-	case CEPH_OSD_OP_STAT:
-		break;
-	case CEPH_OSD_OP_CALL:
-		/* rbd_osd_req_op_create(CALL, class, method, data, datalen) */
-		op->cls.class_name = va_arg(args, char *);
-		size = strlen(op->cls.class_name);
-		rbd_assert(size <= (size_t) U8_MAX);
-		op->cls.class_len = size;
-		op->payload_len = size;
-
-		op->cls.method_name = va_arg(args, char *);
-		size = strlen(op->cls.method_name);
-		rbd_assert(size <= (size_t) U8_MAX);
-		op->cls.method_len = size;
-		op->payload_len += size;
-
-		op->cls.argc = 0;
-		op->cls.indata = va_arg(args, void *);
-		size = va_arg(args, size_t);
-		rbd_assert(size <= (size_t) U32_MAX);
-		op->cls.indata_len = (u32) size;
-		op->payload_len += size;
-		break;
-	case CEPH_OSD_OP_NOTIFY_ACK:
-	case CEPH_OSD_OP_WATCH:
-		/* rbd_osd_req_op_create(NOTIFY_ACK, cookie, version) */
-		/* rbd_osd_req_op_create(WATCH, cookie, version, flag) */
-		op->watch.cookie = va_arg(args, u64);
-		op->watch.ver = va_arg(args, u64);
-		op->watch.ver = cpu_to_le64(op->watch.ver);
-		if (opcode == CEPH_OSD_OP_WATCH && va_arg(args, int))
-			op->watch.flag = (u8) 1;
-		break;
-	default:
-		rbd_warn(NULL, "unsupported opcode %hu\n", opcode);
-		kfree(op);
-		op = NULL;
-		break;
-	}
-	va_end(args);
-
-	return op;
-}
-
-static void rbd_osd_req_op_destroy(struct ceph_osd_req_op *op)
-{
-	kfree(op);
-}
-
 static int rbd_obj_request_submit(struct ceph_osd_client *osdc,
 				struct rbd_obj_request *obj_request)
 {
@@ -1221,7 +1418,24 @@ static int rbd_obj_request_submit(struct ceph_osd_client *osdc,
 
 static void rbd_img_request_complete(struct rbd_img_request *img_request)
 {
+
 	dout("%s: img %p\n", __func__, img_request);
+
+	/*
+	 * If no error occurred, compute the aggregate transfer
+	 * count for the image request.  We could instead use
+	 * atomic64_cmpxchg() to update it as each object request
+	 * completes; not clear which way is better off hand.
+	 */
+	if (!img_request->result) {
+		struct rbd_obj_request *obj_request;
+		u64 xferred = 0;
+
+		for_each_obj_request(img_request, obj_request)
+			xferred += obj_request->xferred;
+		img_request->xferred = xferred;
+	}
+
 	if (img_request->callback)
 		img_request->callback(img_request);
 	else
@@ -1237,39 +1451,56 @@ static int rbd_obj_request_wait(struct rbd_obj_request *obj_request)
 	return wait_for_completion_interruptible(&obj_request->completion);
 }
 
-static void obj_request_done_init(struct rbd_obj_request *obj_request)
+/*
+ * The default/initial value for all image request flags is 0.  Each
+ * is conditionally set to 1 at image request initialization time
+ * and currently never change thereafter.
+ */
+static void img_request_write_set(struct rbd_img_request *img_request)
 {
-	atomic_set(&obj_request->done, 0);
-	smp_wmb();
+	set_bit(IMG_REQ_WRITE, &img_request->flags);
+	smp_mb();
 }
 
-static void obj_request_done_set(struct rbd_obj_request *obj_request)
+static bool img_request_write_test(struct rbd_img_request *img_request)
 {
-	int done;
+	smp_mb();
+	return test_bit(IMG_REQ_WRITE, &img_request->flags) != 0;
+}
 
-	done = atomic_inc_return(&obj_request->done);
-	if (done > 1) {
-		struct rbd_img_request *img_request = obj_request->img_request;
-		struct rbd_device *rbd_dev;
+static void img_request_child_set(struct rbd_img_request *img_request)
+{
+	set_bit(IMG_REQ_CHILD, &img_request->flags);
+	smp_mb();
+}
 
-		rbd_dev = img_request ? img_request->rbd_dev : NULL;
-		rbd_warn(rbd_dev, "obj_request %p was already done\n",
-			obj_request);
-	}
+static bool img_request_child_test(struct rbd_img_request *img_request)
+{
+	smp_mb();
+	return test_bit(IMG_REQ_CHILD, &img_request->flags) != 0;
 }
 
-static bool obj_request_done_test(struct rbd_obj_request *obj_request)
+static void img_request_layered_set(struct rbd_img_request *img_request)
+{
+	set_bit(IMG_REQ_LAYERED, &img_request->flags);
+	smp_mb();
+}
+
+static bool img_request_layered_test(struct rbd_img_request *img_request)
 {
 	smp_mb();
-	return atomic_read(&obj_request->done) != 0;
+	return test_bit(IMG_REQ_LAYERED, &img_request->flags) != 0;
 }
 
 static void
 rbd_img_obj_request_read_callback(struct rbd_obj_request *obj_request)
 {
+	u64 xferred = obj_request->xferred;
+	u64 length = obj_request->length;
+
 	dout("%s: obj %p img %p result %d %llu/%llu\n", __func__,
 		obj_request, obj_request->img_request, obj_request->result,
-		obj_request->xferred, obj_request->length);
+		xferred, length);
 	/*
 	 * ENOENT means a hole in the image.  We zero-fill the
 	 * entire length of the request.  A short read also implies
@@ -1277,15 +1508,20 @@ rbd_img_obj_request_read_callback(struct rbd_obj_request *obj_request)
 	 * update the xferred count to indicate the whole request
 	 * was satisfied.
 	 */
-	BUG_ON(obj_request->type != OBJ_REQUEST_BIO);
+	rbd_assert(obj_request->type != OBJ_REQUEST_NODATA);
 	if (obj_request->result == -ENOENT) {
-		zero_bio_chain(obj_request->bio_list, 0);
+		if (obj_request->type == OBJ_REQUEST_BIO)
+			zero_bio_chain(obj_request->bio_list, 0);
+		else
+			zero_pages(obj_request->pages, 0, length);
 		obj_request->result = 0;
-		obj_request->xferred = obj_request->length;
-	} else if (obj_request->xferred < obj_request->length &&
-			!obj_request->result) {
-		zero_bio_chain(obj_request->bio_list, obj_request->xferred);
-		obj_request->xferred = obj_request->length;
+		obj_request->xferred = length;
+	} else if (xferred < length && !obj_request->result) {
+		if (obj_request->type == OBJ_REQUEST_BIO)
+			zero_bio_chain(obj_request->bio_list, xferred);
+		else
+			zero_pages(obj_request->pages, xferred, length);
+		obj_request->xferred = length;
 	}
 	obj_request_done_set(obj_request);
 }
@@ -1308,9 +1544,23 @@ static void rbd_osd_trivial_callback(struct rbd_obj_request *obj_request)
 
 static void rbd_osd_read_callback(struct rbd_obj_request *obj_request)
 {
-	dout("%s: obj %p result %d %llu/%llu\n", __func__, obj_request,
-		obj_request->result, obj_request->xferred, obj_request->length);
-	if (obj_request->img_request)
+	struct rbd_img_request *img_request = NULL;
+	struct rbd_device *rbd_dev = NULL;
+	bool layered = false;
+
+	if (obj_request_img_data_test(obj_request)) {
+		img_request = obj_request->img_request;
+		layered = img_request && img_request_layered_test(img_request);
+		rbd_dev = img_request->rbd_dev;
+	}
+
+	dout("%s: obj %p img %p result %d %llu/%llu\n", __func__,
+		obj_request, img_request, obj_request->result,
+		obj_request->xferred, obj_request->length);
+	if (layered && obj_request->result == -ENOENT &&
+			obj_request->img_offset < rbd_dev->parent_overlap)
+		rbd_img_parent_read(obj_request);
+	else if (img_request)
 		rbd_img_obj_request_read_callback(obj_request);
 	else
 		obj_request_done_set(obj_request);
@@ -1321,9 +1571,8 @@ static void rbd_osd_write_callback(struct rbd_obj_request *obj_request)
 	dout("%s: obj %p result %d %llu\n", __func__, obj_request,
 		obj_request->result, obj_request->length);
 	/*
-	 * There is no such thing as a successful short write.
-	 * Our xferred value is the number of bytes transferred
-	 * back.  Set it to our originally-requested length.
+	 * There is no such thing as a successful short write.  Set
+	 * it to our originally-requested length.
 	 */
 	obj_request->xferred = obj_request->length;
 	obj_request_done_set(obj_request);
@@ -1347,22 +1596,25 @@ static void rbd_osd_req_callback(struct ceph_osd_request *osd_req,
 
 	dout("%s: osd_req %p msg %p\n", __func__, osd_req, msg);
 	rbd_assert(osd_req == obj_request->osd_req);
-	rbd_assert(!!obj_request->img_request ^
-				(obj_request->which == BAD_WHICH));
+	if (obj_request_img_data_test(obj_request)) {
+		rbd_assert(obj_request->img_request);
+		rbd_assert(obj_request->which != BAD_WHICH);
+	} else {
+		rbd_assert(obj_request->which == BAD_WHICH);
+	}
 
 	if (osd_req->r_result < 0)
 		obj_request->result = osd_req->r_result;
-	obj_request->version = le64_to_cpu(osd_req->r_reassert_version.version);
 
-	WARN_ON(osd_req->r_num_ops != 1);	/* For now */
+	BUG_ON(osd_req->r_num_ops > 2);
 
 	/*
 	 * We support a 64-bit length, but ultimately it has to be
 	 * passed to blk_end_request(), which takes an unsigned int.
 	 */
 	obj_request->xferred = osd_req->r_reply_op_len[0];
-	rbd_assert(obj_request->xferred < (u64) UINT_MAX);
-	opcode = osd_req->r_request_ops[0].op;
+	rbd_assert(obj_request->xferred < (u64)UINT_MAX);
+	opcode = osd_req->r_ops[0].op;
 	switch (opcode) {
 	case CEPH_OSD_OP_READ:
 		rbd_osd_read_callback(obj_request);
@@ -1388,28 +1640,49 @@ static void rbd_osd_req_callback(struct ceph_osd_request *osd_req,
 		rbd_obj_request_complete(obj_request);
 }
 
+static void rbd_osd_req_format_read(struct rbd_obj_request *obj_request)
+{
+	struct rbd_img_request *img_request = obj_request->img_request;
+	struct ceph_osd_request *osd_req = obj_request->osd_req;
+	u64 snap_id;
+
+	rbd_assert(osd_req != NULL);
+
+	snap_id = img_request ? img_request->snap_id : CEPH_NOSNAP;
+	ceph_osdc_build_request(osd_req, obj_request->offset,
+			NULL, snap_id, NULL);
+}
+
+static void rbd_osd_req_format_write(struct rbd_obj_request *obj_request)
+{
+	struct rbd_img_request *img_request = obj_request->img_request;
+	struct ceph_osd_request *osd_req = obj_request->osd_req;
+	struct ceph_snap_context *snapc;
+	struct timespec mtime = CURRENT_TIME;
+
+	rbd_assert(osd_req != NULL);
+
+	snapc = img_request ? img_request->snapc : NULL;
+	ceph_osdc_build_request(osd_req, obj_request->offset,
+			snapc, CEPH_NOSNAP, &mtime);
+}
+
 static struct ceph_osd_request *rbd_osd_req_create(
 					struct rbd_device *rbd_dev,
 					bool write_request,
-					struct rbd_obj_request *obj_request,
-					struct ceph_osd_req_op *op)
+					struct rbd_obj_request *obj_request)
 {
-	struct rbd_img_request *img_request = obj_request->img_request;
 	struct ceph_snap_context *snapc = NULL;
 	struct ceph_osd_client *osdc;
 	struct ceph_osd_request *osd_req;
-	struct timespec now;
-	struct timespec *mtime;
-	u64 snap_id = CEPH_NOSNAP;
-	u64 offset = obj_request->offset;
-	u64 length = obj_request->length;
 
-	if (img_request) {
-		rbd_assert(img_request->write_request == write_request);
-		if (img_request->write_request)
+	if (obj_request_img_data_test(obj_request)) {
+		struct rbd_img_request *img_request = obj_request->img_request;
+
+		rbd_assert(write_request ==
+				img_request_write_test(img_request));
+		if (write_request)
 			snapc = img_request->snapc;
-		else
-			snap_id = img_request->snap_id;
 	}
 
 	/* Allocate and initialize the request, for the single op */
@@ -1419,31 +1692,10 @@ static struct ceph_osd_request *rbd_osd_req_create(
 	if (!osd_req)
 		return NULL;	/* ENOMEM */
 
-	rbd_assert(obj_request_type_valid(obj_request->type));
-	switch (obj_request->type) {
-	case OBJ_REQUEST_NODATA:
-		break;		/* Nothing to do */
-	case OBJ_REQUEST_BIO:
-		rbd_assert(obj_request->bio_list != NULL);
-		osd_req->r_bio = obj_request->bio_list;
-		break;
-	case OBJ_REQUEST_PAGES:
-		osd_req->r_pages = obj_request->pages;
-		osd_req->r_num_pages = obj_request->page_count;
-		osd_req->r_page_alignment = offset & ~PAGE_MASK;
-		break;
-	}
-
-	if (write_request) {
+	if (write_request)
 		osd_req->r_flags = CEPH_OSD_FLAG_WRITE | CEPH_OSD_FLAG_ONDISK;
-		now = CURRENT_TIME;
-		mtime = &now;