linux/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/striper.h>
#include <linux/ceph/types.h>

/*
 * Map a file extent to a stripe unit within an object.
 * Fill in objno, offset into object, and object extent length (i.e. the
 * number of bytes mapped, less than or equal to @l->stripe_unit).
 *
 * Example for stripe_count = 3, stripes_per_object = 4:
 *
 * blockno   |  0  3  6  9 |  1  4  7 10 |  2  5  8 11 | 12 15 18 21 | 13 16 19
 * stripeno  |  0  1  2  3 |  0  1  2  3 |  0  1  2  3 |  4  5  6  7 |  4  5  6
 * stripepos |      0      |      1      |      2      |      0      |      1
 * objno     |      0      |      1      |      2      |      3      |      4
 * objsetno  |                    0                    |                    1
 */
void ceph_calc_file_object_mapping(struct ceph_file_layout *l,
				   u64 off, u64 len,
				   u64 *objno, u64 *objoff, u32 *xlen)
{ … }
EXPORT_SYMBOL(…);

/*
 * 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)
{ … }

static struct ceph_object_extent *
lookup_containing(struct list_head *object_extents, u64 objno,
		  u64 objoff, u32 xlen)
{ … }

/*
 * 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)
{ … }
EXPORT_SYMBOL(…);

/*
 * 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)
{ … }
EXPORT_SYMBOL(…);

/*
 * 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)
{ … }
EXPORT_SYMBOL(…);

u64 ceph_get_num_objects(struct ceph_file_layout *l, u64 size)
{ … }
EXPORT_SYMBOL(…);