libceph: striping framework implementation

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

2 files changed, 227 insertions, 0 deletions

diff --git a/net/ceph/Makefile b/net/ceph/Makefile
index b4bded4b5396..12bf49772d24 100644
--- a/net/ceph/Makefile
+++ b/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 \
diff --git a/net/ceph/striper.c b/net/ceph/striper.c
new file mode 100644
index 000000000000..bc1e4de30df9
--- /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);