libceph: striping framework implementation

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

include/linux/ceph/striper.h

+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_CEPH_STRIPER_H
+#define _LINUX_CEPH_STRIPER_H
+
+#include <linux/list.h>
+#include <linux/types.h>
+
+struct ceph_file_layout;
+
+struct ceph_object_extent {
+	struct list_head oe_item;
+	u64 oe_objno;
+	u64 oe_off;
+	u64 oe_len;
+};
+
+static inline void ceph_object_extent_init(struct ceph_object_extent *ex)
+{
+	INIT_LIST_HEAD(&ex->oe_item);
+}
+
+/*
+ * Called for each mapped stripe unit.
+ *
+ * @bytes: number of bytes mapped, i.e. the minimum of the full length
+ *         requested (file extent length) or the remainder of the stripe
+ *         unit within an object
+ */
+typedef void (*ceph_object_extent_fn_t)(struct ceph_object_extent *ex,
+					u32 bytes, void *arg);
+
+int ceph_file_to_extents(struct ceph_file_layout *l, u64 off, u64 len,
+			 struct list_head *object_extents,
+			 struct ceph_object_extent *alloc_fn(void *arg),
+			 void *alloc_arg,
+			 ceph_object_extent_fn_t action_fn,
+			 void *action_arg);
+int ceph_iterate_extents(struct ceph_file_layout *l, u64 off, u64 len,
+			 struct list_head *object_extents,
+			 ceph_object_extent_fn_t action_fn,
+			 void *action_arg);
+
+struct ceph_file_extent {
+	u64 fe_off;
+	u64 fe_len;
+};
+
+static inline u64 ceph_file_extents_bytes(struct ceph_file_extent *file_extents,
+					  u32 num_file_extents)
+{
+	u64 bytes = 0;
+	u32 i;
+
+	for (i = 0; i < num_file_extents; i++)
+		bytes += file_extents[i].fe_len;
+
+	return bytes;
+}
+
+int ceph_extent_to_file(struct ceph_file_layout *l,
+			u64 objno, u64 objoff, u64 objlen,
+			struct ceph_file_extent **file_extents,
+			u32 *num_file_extents);
+
+#endif

net/ceph/Makefile

@@ -8,6 +8,7 @@ libceph-y := ceph_common.o messenger.o msgpool.o buffer.o pagelist.o \
 	mon_client.o \
 	cls_lock_client.o \
 	osd_client.o osdmap.o crush/crush.o crush/mapper.o crush/hash.o \
+	striper.o \
 	debugfs.o \
 	auth.o auth_none.o \
 	crypto.o armor.o \

net/ceph/striper.c

+/* SPDX-License-Identifier: GPL-2.0 */
+
+#include <linux/ceph/ceph_debug.h>
+
+#include <linux/math64.h>
+#include <linux/slab.h>
+
+#include <linux/ceph/osdmap.h>
+#include <linux/ceph/striper.h>
+#include <linux/ceph/types.h>
+
+/*
+ * Return the last extent with given objno (@object_extents is sorted
+ * by objno).  If not found, return NULL and set @add_pos so that the
+ * new extent can be added with list_add(add_pos, new_ex).
+ */
+static struct ceph_object_extent *
+lookup_last(struct list_head *object_extents, u64 objno,
+	    struct list_head **add_pos)
+{
+	struct list_head *pos;
+
+	list_for_each_prev(pos, object_extents) {
+		struct ceph_object_extent *ex =
+		    list_entry(pos, typeof(*ex), oe_item);
+
+		if (ex->oe_objno == objno)
+			return ex;
+
+		if (ex->oe_objno < objno)
+			break;
+	}
+
+	*add_pos = pos;
+	return NULL;
+}
+
+static struct ceph_object_extent *
+lookup_containing(struct list_head *object_extents, u64 objno,
+		  u64 objoff, u32 xlen)
+{
+	struct ceph_object_extent *ex;
+
+	list_for_each_entry(ex, object_extents, oe_item) {
+		if (ex->oe_objno == objno &&
+		    ex->oe_off <= objoff &&
+		    ex->oe_off + ex->oe_len >= objoff + xlen) /* paranoia */
+			return ex;
+
+		if (ex->oe_objno > objno)
+			break;
+	}
+
+	return NULL;
+}
+
+/*
+ * Map a file extent to a sorted list of object extents.
+ *
+ * We want only one (or as few as possible) object extents per object.
+ * Adjacent object extents will be merged together, each returned object
+ * extent may reverse map to multiple different file extents.
+ *
+ * Call @alloc_fn for each new object extent and @action_fn for each
+ * mapped stripe unit, whether it was merged into an already allocated
+ * object extent or started a new object extent.
+ *
+ * Newly allocated object extents are added to @object_extents.
+ * To keep @object_extents sorted, successive calls to this function
+ * must map successive file extents (i.e. the list of file extents that
+ * are mapped using the same @object_extents must be sorted).
+ *
+ * The caller is responsible for @object_extents.
+ */
+int ceph_file_to_extents(struct ceph_file_layout *l, u64 off, u64 len,
+			 struct list_head *object_extents,
+			 struct ceph_object_extent *alloc_fn(void *arg),
+			 void *alloc_arg,
+			 ceph_object_extent_fn_t action_fn,
+			 void *action_arg)
+{
+	struct ceph_object_extent *last_ex, *ex;
+
+	while (len) {
+		struct list_head *add_pos = NULL;
+		u64 objno, objoff;
+		u32 xlen;
+
+		ceph_calc_file_object_mapping(l, off, len, &objno, &objoff,
+					      &xlen);
+
+		last_ex = lookup_last(object_extents, objno, &add_pos);
+		if (!last_ex || last_ex->oe_off + last_ex->oe_len != objoff) {
+			ex = alloc_fn(alloc_arg);
+			if (!ex)
+				return -ENOMEM;
+
+			ex->oe_objno = objno;
+			ex->oe_off = objoff;
+			ex->oe_len = xlen;
+			if (action_fn)
+				action_fn(ex, xlen, action_arg);
+
+			if (!last_ex)
+				list_add(&ex->oe_item, add_pos);
+			else
+				list_add(&ex->oe_item, &last_ex->oe_item);
+		} else {
+			last_ex->oe_len += xlen;
+			if (action_fn)
+				action_fn(last_ex, xlen, action_arg);
+		}
+
+		off += xlen;
+		len -= xlen;
+	}
+
+	for (last_ex = list_first_entry(object_extents, typeof(*ex), oe_item),
+	     ex = list_next_entry(last_ex, oe_item);
+	     &ex->oe_item != object_extents;
+	     last_ex = ex, ex = list_next_entry(ex, oe_item)) {
+		if (last_ex->oe_objno > ex->oe_objno ||
+		    (last_ex->oe_objno == ex->oe_objno &&
+		     last_ex->oe_off + last_ex->oe_len >= ex->oe_off)) {
+			WARN(1, "%s: object_extents list not sorted!\n",
+			     __func__);
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(ceph_file_to_extents);
+
+/*
+ * A stripped down, non-allocating version of ceph_file_to_extents(),
+ * for when @object_extents is already populated.
+ */
+int ceph_iterate_extents(struct ceph_file_layout *l, u64 off, u64 len,
+			 struct list_head *object_extents,
+			 ceph_object_extent_fn_t action_fn,
+			 void *action_arg)
+{
+	while (len) {
+		struct ceph_object_extent *ex;
+		u64 objno, objoff;
+		u32 xlen;
+
+		ceph_calc_file_object_mapping(l, off, len, &objno, &objoff,
+					      &xlen);
+
+		ex = lookup_containing(object_extents, objno, objoff, xlen);
+		if (!ex) {
+			WARN(1, "%s: objno %llu %llu~%u not found!\n",
+			     __func__, objno, objoff, xlen);
+			return -EINVAL;
+		}
+
+		action_fn(ex, xlen, action_arg);
+
+		off += xlen;
+		len -= xlen;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(ceph_iterate_extents);
+
+/*
+ * Reverse map an object extent to a sorted list of file extents.
+ *
+ * On success, the caller is responsible for:
+ *
+ *     kfree(file_extents)
+ */
+int ceph_extent_to_file(struct ceph_file_layout *l,
+			u64 objno, u64 objoff, u64 objlen,
+			struct ceph_file_extent **file_extents,
+			u32 *num_file_extents)
+{
+	u32 stripes_per_object = l->object_size / l->stripe_unit;
+	u64 blockno;	/* which su */
+	u32 blockoff;	/* offset into su */
+	u64 stripeno;	/* which stripe */
+	u32 stripepos;	/* which su in the stripe,
+			   which object in the object set */
+	u64 objsetno;	/* which object set */
+	u32 i = 0;
+
+	if (!objlen) {
+		*file_extents = NULL;
+		*num_file_extents = 0;
+		return 0;
+	}
+
+	*num_file_extents = DIV_ROUND_UP_ULL(objoff + objlen, l->stripe_unit) -
+				     DIV_ROUND_DOWN_ULL(objoff, l->stripe_unit);
+	*file_extents = kmalloc_array(*num_file_extents, sizeof(**file_extents),
+				      GFP_NOIO);
+	if (!*file_extents)
+		return -ENOMEM;
+
+	div_u64_rem(objoff, l->stripe_unit, &blockoff);
+	while (objlen) {
+		u64 off, len;
+
+		objsetno = div_u64_rem(objno, l->stripe_count, &stripepos);
+		stripeno = div_u64(objoff, l->stripe_unit) +
+						objsetno * stripes_per_object;
+		blockno = stripeno * l->stripe_count + stripepos;
+		off = blockno * l->stripe_unit + blockoff;
+		len = min_t(u64, objlen, l->stripe_unit - blockoff);
+
+		(*file_extents)[i].fe_off = off;
+		(*file_extents)[i].fe_len = len;
+
+		blockoff = 0;
+		objoff += len;
+		objlen -= len;
+		i++;
+	}
+
+	BUG_ON(i != *num_file_extents);
+	return 0;
+}
+EXPORT_SYMBOL(ceph_extent_to_file);