libceph: striping framework implementation
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
diff --git a/net/ceph/striper.c b/net/ceph/striper.c
new file mode 100644
index 0000000..bc1e4de
--- /dev/null
+++ b/net/ceph/striper.c
@@ -0,0 +1,226 @@
+/* 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);
