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/*
* linux/fs/nfs/blocklayout/blocklayout.h
*
* Module for the NFSv4.1 pNFS block layout driver.
*
* Copyright (c) 2006 The Regents of the University of Michigan.
* All rights reserved.
*
* Andy Adamson <andros@citi.umich.edu>
* Fred Isaman <iisaman@umich.edu>
*
* permission is granted to use, copy, create derivative works and
* redistribute this software and such derivative works for any purpose,
* so long as the name of the university of michigan is not used in
* any advertising or publicity pertaining to the use or distribution
* of this software without specific, written prior authorization. if
* the above copyright notice or any other identification of the
* university of michigan is included in any copy of any portion of
* this software, then the disclaimer below must also be included.
*
* this software is provided as is, without representation from the
* university of michigan as to its fitness for any purpose, and without
* warranty by the university of michigan of any kind, either express
* or implied, including without limitation the implied warranties of
* merchantability and fitness for a particular purpose. the regents
* of the university of michigan shall not be liable for any damages,
* including special, indirect, incidental, or consequential damages,
* with respect to any claim arising out or in connection with the use
* of the software, even if it has been or is hereafter advised of the
* possibility of such damages.
*/
#include "blocklayout.h"
#define NFSDBG_FACILITY NFSDBG_PNFS_LD
static void print_bl_extent(struct pnfs_block_extent *be)
{
dprintk("PRINT EXTENT extent %p\n", be);
if (be) {
dprintk(" be_f_offset %llu\n", (u64)be->be_f_offset);
dprintk(" be_length %llu\n", (u64)be->be_length);
dprintk(" be_v_offset %llu\n", (u64)be->be_v_offset);
dprintk(" be_state %d\n", be->be_state);
}
}
static void
destroy_extent(struct kref *kref)
{
struct pnfs_block_extent *be;
be = container_of(kref, struct pnfs_block_extent, be_refcnt);
dprintk("%s be=%p\n", __func__, be);
kfree(be);
}
void
bl_put_extent(struct pnfs_block_extent *be)
{
if (be) {
dprintk("%s enter %p (%i)\n", __func__, be,
atomic_read(&be->be_refcnt.refcount));
kref_put(&be->be_refcnt, destroy_extent);
}
}
struct pnfs_block_extent *bl_alloc_extent(void)
{
struct pnfs_block_extent *be;
be = kmalloc(sizeof(struct pnfs_block_extent), GFP_NOFS);
if (!be)
return NULL;
INIT_LIST_HEAD(&be->be_node);
kref_init(&be->be_refcnt);
be->be_inval = NULL;
return be;
}
static void print_elist(struct list_head *list)
{
struct pnfs_block_extent *be;
dprintk("****************\n");
dprintk("Extent list looks like:\n");
list_for_each_entry(be, list, be_node) {
print_bl_extent(be);
}
dprintk("****************\n");
}
static inline int
extents_consistent(struct pnfs_block_extent *old, struct pnfs_block_extent *new)
{
/* Note this assumes new->be_f_offset >= old->be_f_offset */
return (new->be_state == old->be_state) &&
((new->be_state == PNFS_BLOCK_NONE_DATA) ||
((new->be_v_offset - old->be_v_offset ==
new->be_f_offset - old->be_f_offset) &&
new->be_mdev == old->be_mdev));
}
/* Adds new to appropriate list in bl, modifying new and removing existing
* extents as appropriate to deal with overlaps.
*
* See bl_find_get_extent for list constraints.
*
* Refcount on new is already set. If end up not using it, or error out,
* need to put the reference.
*
* bl->bl_ext_lock is held by caller.
*/
int
bl_add_merge_extent(struct pnfs_block_layout *bl,
struct pnfs_block_extent *new)
{
struct pnfs_block_extent *be, *tmp;
sector_t end = new->be_f_offset + new->be_length;
struct list_head *list;
dprintk("%s enter with be=%p\n", __func__, new);
print_bl_extent(new);
list = &bl->bl_extents[bl_choose_list(new->be_state)];
print_elist(list);
/* Scan for proper place to insert, extending new to the left
* as much as possible.
*/
list_for_each_entry_safe(be, tmp, list, be_node) {
if (new->be_f_offset < be->be_f_offset)
break;
if (end <= be->be_f_offset + be->be_length) {
/* new is a subset of existing be*/
if (extents_consistent(be, new)) {
dprintk("%s: new is subset, ignoring\n",
__func__);
bl_put_extent(new);
return 0;
} else
goto out_err;
} else if (new->be_f_offset <=
be->be_f_offset + be->be_length) {
/* new overlaps or abuts existing be */
if (extents_consistent(be, new)) {
/* extend new to fully replace be */
new->be_length += new->be_f_offset -
be->be_f_offset;
new->be_f_offset = be->be_f_offset;
new->be_v_offset = be->be_v_offset;
dprintk("%s: removing %p\n", __func__, be);
list_del(&be->be_node);
bl_put_extent(be);
} else if (new->be_f_offset !=
be->be_f_offset + be->be_length)
goto out_err;
}
}
/* Note that if we never hit the above break, be will not point to a
* valid extent. However, in that case &be->be_node==list.
*/
list_add_tail(&new->be_node, &be->be_node);
dprintk("%s: inserting new\n", __func__);
print_elist(list);
/* Scan forward for overlaps. If we find any, extend new and
* remove the overlapped extent.
*/
be = list_prepare_entry(new, list, be_node);
list_for_each_entry_safe_continue(be, tmp, list, be_node) {
if (end < be->be_f_offset)
break;
/* new overlaps or abuts existing be */
if (extents_consistent(be, new)) {
if (end < be->be_f_offset + be->be_length) {
/* extend new to fully cover be */
end = be->be_f_offset + be->be_length;
new->be_length = end - new->be_f_offset;
}
dprintk("%s: removing %p\n", __func__, be);
list_del(&be->be_node);
bl_put_extent(be);
} else if (end != be->be_f_offset) {
list_del(&new->be_node);
goto out_err;
}
}
dprintk("%s: after merging\n", __func__);
print_elist(list);
/* FIXME - The per-list consistency checks have all been done,
* should now check cross-list consistency.
*/
return 0;
out_err:
bl_put_extent(new);
return -EIO;
}
/* Returns extent, or NULL. If a second READ extent exists, it is returned
* in cow_read, if given.
*
* The extents are kept in two seperate ordered lists, one for READ and NONE,
* one for READWRITE and INVALID. Within each list, we assume:
* 1. Extents are ordered by file offset.
* 2. For any given isect, there is at most one extents that matches.
*/
struct pnfs_block_extent *
bl_find_get_extent(struct pnfs_block_layout *bl, sector_t isect,
struct pnfs_block_extent **cow_read)
{
struct pnfs_block_extent *be, *cow, *ret;
int i;
dprintk("%s enter with isect %llu\n", __func__, (u64)isect);
cow = ret = NULL;
spin_lock(&bl->bl_ext_lock);
for (i = 0; i < EXTENT_LISTS; i++) {
list_for_each_entry_reverse(be, &bl->bl_extents[i], be_node) {
if (isect >= be->be_f_offset + be->be_length)
break;
if (isect >= be->be_f_offset) {
/* We have found an extent */
dprintk("%s Get %p (%i)\n", __func__, be,
atomic_read(&be->be_refcnt.refcount));
kref_get(&be->be_refcnt);
if (!ret)
ret = be;
else if (be->be_state != PNFS_BLOCK_READ_DATA)
bl_put_extent(be);
else
cow = be;
break;
}
}
if (ret &&
(!cow_read || ret->be_state != PNFS_BLOCK_INVALID_DATA))
break;
}
spin_unlock(&bl->bl_ext_lock);
if (cow_read)
*cow_read = cow;
print_bl_extent(ret);
return ret;
}
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