262 lines
7.2 KiB
C
262 lines
7.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#include <linux/ceph/ceph_debug.h>
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#include <linux/math64.h>
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#include <linux/slab.h>
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#include <linux/ceph/striper.h>
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#include <linux/ceph/types.h>
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/*
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* Map a file extent to a stripe unit within an object.
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* Fill in objno, offset into object, and object extent length (i.e. the
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* number of bytes mapped, less than or equal to @l->stripe_unit).
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*
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* Example for stripe_count = 3, stripes_per_object = 4:
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*
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* blockno | 0 3 6 9 | 1 4 7 10 | 2 5 8 11 | 12 15 18 21 | 13 16 19
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* stripeno | 0 1 2 3 | 0 1 2 3 | 0 1 2 3 | 4 5 6 7 | 4 5 6
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* stripepos | 0 | 1 | 2 | 0 | 1
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* objno | 0 | 1 | 2 | 3 | 4
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* objsetno | 0 | 1
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*/
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void ceph_calc_file_object_mapping(struct ceph_file_layout *l,
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u64 off, u64 len,
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u64 *objno, u64 *objoff, u32 *xlen)
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{
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u32 stripes_per_object = l->object_size / l->stripe_unit;
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u64 blockno; /* which su in the file (i.e. globally) */
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u32 blockoff; /* offset into su */
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u64 stripeno; /* which stripe */
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u32 stripepos; /* which su in the stripe,
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which object in the object set */
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u64 objsetno; /* which object set */
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u32 objsetpos; /* which stripe in the object set */
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blockno = div_u64_rem(off, l->stripe_unit, &blockoff);
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stripeno = div_u64_rem(blockno, l->stripe_count, &stripepos);
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objsetno = div_u64_rem(stripeno, stripes_per_object, &objsetpos);
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*objno = objsetno * l->stripe_count + stripepos;
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*objoff = objsetpos * l->stripe_unit + blockoff;
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*xlen = min_t(u64, len, l->stripe_unit - blockoff);
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}
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EXPORT_SYMBOL(ceph_calc_file_object_mapping);
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/*
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* Return the last extent with given objno (@object_extents is sorted
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* by objno). If not found, return NULL and set @add_pos so that the
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* new extent can be added with list_add(add_pos, new_ex).
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*/
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static struct ceph_object_extent *
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lookup_last(struct list_head *object_extents, u64 objno,
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struct list_head **add_pos)
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{
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struct list_head *pos;
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list_for_each_prev(pos, object_extents) {
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struct ceph_object_extent *ex =
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list_entry(pos, typeof(*ex), oe_item);
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if (ex->oe_objno == objno)
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return ex;
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if (ex->oe_objno < objno)
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break;
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}
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*add_pos = pos;
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return NULL;
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}
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static struct ceph_object_extent *
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lookup_containing(struct list_head *object_extents, u64 objno,
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u64 objoff, u32 xlen)
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{
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struct ceph_object_extent *ex;
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list_for_each_entry(ex, object_extents, oe_item) {
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if (ex->oe_objno == objno &&
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ex->oe_off <= objoff &&
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ex->oe_off + ex->oe_len >= objoff + xlen) /* paranoia */
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return ex;
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if (ex->oe_objno > objno)
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break;
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}
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return NULL;
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}
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/*
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* Map a file extent to a sorted list of object extents.
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*
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* We want only one (or as few as possible) object extents per object.
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* Adjacent object extents will be merged together, each returned object
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* extent may reverse map to multiple different file extents.
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*
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* Call @alloc_fn for each new object extent and @action_fn for each
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* mapped stripe unit, whether it was merged into an already allocated
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* object extent or started a new object extent.
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*
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* Newly allocated object extents are added to @object_extents.
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* To keep @object_extents sorted, successive calls to this function
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* must map successive file extents (i.e. the list of file extents that
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* are mapped using the same @object_extents must be sorted).
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*
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* The caller is responsible for @object_extents.
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*/
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int ceph_file_to_extents(struct ceph_file_layout *l, u64 off, u64 len,
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struct list_head *object_extents,
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struct ceph_object_extent *alloc_fn(void *arg),
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void *alloc_arg,
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ceph_object_extent_fn_t action_fn,
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void *action_arg)
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{
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struct ceph_object_extent *last_ex, *ex;
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while (len) {
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struct list_head *add_pos = NULL;
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u64 objno, objoff;
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u32 xlen;
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ceph_calc_file_object_mapping(l, off, len, &objno, &objoff,
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&xlen);
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last_ex = lookup_last(object_extents, objno, &add_pos);
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if (!last_ex || last_ex->oe_off + last_ex->oe_len != objoff) {
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ex = alloc_fn(alloc_arg);
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if (!ex)
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return -ENOMEM;
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ex->oe_objno = objno;
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ex->oe_off = objoff;
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ex->oe_len = xlen;
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if (action_fn)
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action_fn(ex, xlen, action_arg);
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if (!last_ex)
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list_add(&ex->oe_item, add_pos);
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else
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list_add(&ex->oe_item, &last_ex->oe_item);
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} else {
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last_ex->oe_len += xlen;
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if (action_fn)
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action_fn(last_ex, xlen, action_arg);
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}
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off += xlen;
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len -= xlen;
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}
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for (last_ex = list_first_entry(object_extents, typeof(*ex), oe_item),
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ex = list_next_entry(last_ex, oe_item);
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&ex->oe_item != object_extents;
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last_ex = ex, ex = list_next_entry(ex, oe_item)) {
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if (last_ex->oe_objno > ex->oe_objno ||
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(last_ex->oe_objno == ex->oe_objno &&
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last_ex->oe_off + last_ex->oe_len >= ex->oe_off)) {
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WARN(1, "%s: object_extents list not sorted!\n",
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__func__);
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return -EINVAL;
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}
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}
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return 0;
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}
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EXPORT_SYMBOL(ceph_file_to_extents);
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/*
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* A stripped down, non-allocating version of ceph_file_to_extents(),
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* for when @object_extents is already populated.
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*/
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int ceph_iterate_extents(struct ceph_file_layout *l, u64 off, u64 len,
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struct list_head *object_extents,
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ceph_object_extent_fn_t action_fn,
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void *action_arg)
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{
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while (len) {
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struct ceph_object_extent *ex;
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u64 objno, objoff;
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u32 xlen;
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ceph_calc_file_object_mapping(l, off, len, &objno, &objoff,
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&xlen);
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ex = lookup_containing(object_extents, objno, objoff, xlen);
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if (!ex) {
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WARN(1, "%s: objno %llu %llu~%u not found!\n",
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__func__, objno, objoff, xlen);
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return -EINVAL;
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}
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action_fn(ex, xlen, action_arg);
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off += xlen;
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len -= xlen;
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}
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return 0;
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}
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EXPORT_SYMBOL(ceph_iterate_extents);
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/*
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* Reverse map an object extent to a sorted list of file extents.
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*
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* On success, the caller is responsible for:
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*
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* kfree(file_extents)
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*/
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int ceph_extent_to_file(struct ceph_file_layout *l,
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u64 objno, u64 objoff, u64 objlen,
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struct ceph_file_extent **file_extents,
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u32 *num_file_extents)
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{
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u32 stripes_per_object = l->object_size / l->stripe_unit;
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u64 blockno; /* which su */
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u32 blockoff; /* offset into su */
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u64 stripeno; /* which stripe */
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u32 stripepos; /* which su in the stripe,
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which object in the object set */
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u64 objsetno; /* which object set */
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u32 i = 0;
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if (!objlen) {
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*file_extents = NULL;
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*num_file_extents = 0;
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return 0;
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}
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*num_file_extents = DIV_ROUND_UP_ULL(objoff + objlen, l->stripe_unit) -
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DIV_ROUND_DOWN_ULL(objoff, l->stripe_unit);
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*file_extents = kmalloc_array(*num_file_extents, sizeof(**file_extents),
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GFP_NOIO);
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if (!*file_extents)
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return -ENOMEM;
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div_u64_rem(objoff, l->stripe_unit, &blockoff);
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while (objlen) {
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u64 off, len;
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objsetno = div_u64_rem(objno, l->stripe_count, &stripepos);
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stripeno = div_u64(objoff, l->stripe_unit) +
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objsetno * stripes_per_object;
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blockno = stripeno * l->stripe_count + stripepos;
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off = blockno * l->stripe_unit + blockoff;
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len = min_t(u64, objlen, l->stripe_unit - blockoff);
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(*file_extents)[i].fe_off = off;
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(*file_extents)[i].fe_len = len;
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blockoff = 0;
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objoff += len;
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objlen -= len;
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i++;
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}
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BUG_ON(i != *num_file_extents);
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return 0;
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}
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EXPORT_SYMBOL(ceph_extent_to_file);
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