/* -*- mode: c; c-basic-offset: 8; -*-
* vim: noexpandtab sw=8 ts=8 sts=0:
*
* reservations.c
*
* Allocation reservations implementation
*
* Some code borrowed from fs/ext3/balloc.c and is:
*
* Copyright (C) 1992, 1993, 1994, 1995
* Remy Card (card@masi.ibp.fr)
* Laboratoire MASI - Institut Blaise Pascal
* Universite Pierre et Marie Curie (Paris VI)
*
* The rest is copyright (C) 2010 Novell. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License version 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*/
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/highmem.h>
#include <linux/bitops.h>
#include <linux/list.h>
#define MLOG_MASK_PREFIX ML_RESERVATIONS
#include <cluster/masklog.h>
#include "ocfs2.h"
#ifdef CONFIG_OCFS2_DEBUG_FS
#define OCFS2_CHECK_RESERVATIONS
#endif
DEFINE_SPINLOCK(resv_lock);
#define OCFS2_MIN_RESV_WINDOW_BITS 8
#define OCFS2_MAX_RESV_WINDOW_BITS 1024
int ocfs2_dir_resv_allowed(struct ocfs2_super *osb)
{
return (osb->osb_resv_level && osb->osb_dir_resv_level);
}
static unsigned int ocfs2_resv_window_bits(struct ocfs2_reservation_map *resmap,
struct ocfs2_alloc_reservation *resv)
{
struct ocfs2_super *osb = resmap->m_osb;
unsigned int bits;
if (!(resv->r_flags & OCFS2_RESV_FLAG_DIR)) {
/* 8, 16, 32, 64, 128, 256, 512, 1024 */
bits = 4 << osb->osb_resv_level;
} else {
bits = 4 << osb->osb_dir_resv_level;
}
return bits;
}
static inline unsigned int ocfs2_resv_end(struct ocfs2_alloc_reservation *resv)
{
if (resv->r_len)
return resv->r_start + resv->r_len - 1;
return resv->r_start;
}
static inline int ocfs2_resv_empty(struct ocfs2_alloc_reservation *resv)
{
return !!(resv->r_len == 0);
}
static inline int ocfs2_resmap_disabled(struct ocfs2_reservation_map *resmap)
{
if (resmap->m_osb->osb_resv_level == 0)
return 1;
return 0;
}
static void ocfs2_dump_resv(struct ocfs2_reservation_map *resmap)
{
struct ocfs2_super *osb = resmap->m_osb;
struct rb_node *node;
struct ocfs2_alloc_reservation *resv;
int i = 0;
mlog(ML_NOTICE, "Dumping resmap for device %s. Bitmap length: %u\n",
osb->dev_str, resmap->m_bitmap_len);
node = rb_first(&resmap->m_reservations);
while (node) {
resv = rb_entry(node, struct ocfs2_alloc_reservation, r_node);
mlog(ML_NOTICE, "start: %u\tend: %u\tlen: %u\tlast_start: %u"
"\tlast_len: %u\n", resv->r_start,
ocfs2_resv_end(resv), resv->r_len, resv->r_last_start,
resv->r_last_len);
node = rb_next(node);
i++;
}
mlog(ML_NOTICE, "%d reservations found. LRU follows\n", i);
i = 0;
list_for_each_entry(resv, &resmap->m_lru, r_lru) {
mlog(ML_NOTICE, "LRU(%d) start: %u\tend: %u\tlen: %u\t"
"last_start: %u\tlast_len: %u\n", i, resv->r_start,
ocfs2_resv_end(resv), resv->r_len, resv->r_last_start,
resv->r_last_len);
i++;
}
}
#ifdef OCFS2_CHECK_RESERVATIONS
static int ocfs2_validate_resmap_bits(struct ocfs2_reservation_map *resmap,
int i,
struct ocfs2_alloc_reservation *resv)
{
char *disk_bitmap = resmap->m_disk_bitmap;
unsigned int start = resv->r_start;
unsigned int end = ocfs2_resv_end(resv);
while (start <= end) {
if (ocfs2_test_bit(start, disk_bitmap)) {
mlog(ML_ERROR,
"reservation %d covers an allocated area "
"starting at bit %u!\n", i, start);
return 1;
}
start++;
}
return 0;
}
static void ocfs2_check_resmap(struct ocfs2_reservation_map *resmap)
{
unsigned int off = 0;
int i = 0;
struct rb_node *node;
struct ocfs2_alloc_reservation *resv;
node = rb_first(&resmap->m_reservations);
while (node) {
resv = rb_entry(node, struct ocfs2_alloc_reservation, r_node);
if (i > 0 && resv->r_start <= off) {
mlog(ML_ERROR, "reservation %d has bad start off!\n",
i);
goto bad;
}
if (resv->r_len == 0) {
mlog(ML_ERROR, "reservation %d has no length!\n",
i);
goto bad;
}
if (resv->r_start > ocfs2_resv_end(resv)) {
mlog(ML_ERROR, "reservation %d has invalid range!\n",
i);
goto bad;
}
if (ocfs2_resv_end(resv) >= resmap->m_bitmap_len) {
mlog(ML_ERROR, "reservation %d extends past bitmap!\n",
i);
goto bad;
}
if (ocfs2_validate_resmap_bits(resmap, i, resv))
goto bad;
off = ocfs2_resv_end(resv);
node = rb_next(node);
i++;
}
return;
bad:
ocfs2_dump_resv(resmap);
BUG();
}
#else
static inline void ocfs2_check_resmap(struct ocfs2_reservation_map *resmap)
{
}
#endif
void ocfs2_resv_init_once(struct ocfs2_alloc_reservation *resv)
{
memset(resv, 0, sizeof(*resv));
INIT_LIST_HEAD(&resv->r_lru);
}
void ocfs2_resv_set_type(struct ocfs2_alloc_reservation *resv,
unsigned int flags)
{
BUG_ON(flags & ~OCFS2_RESV_TYPES);
resv->r_flags |= flags;
}
int ocfs2_resmap_init(struct ocfs2_super *osb,
struct ocfs2_reservation_map *resmap)
{
memset(resmap, 0, sizeof(*resmap));
resmap->m_osb = osb;
resmap->m_reservations = RB_ROOT;
/* m_bitmap_len is initialized to zero by the above memset. */
INIT_LIST_HEAD(&resmap->m_lru);
return 0;
}
static void ocfs2_resv_mark_lru(struct ocfs2_reservation_map *resmap,
struct ocfs2_alloc_reservation *resv)
{
assert_spin_locked(&resv_lock);
if (!list_empty(&resv->r_lru))
list_del_init(&resv->r_lru);
list_add_tail(&resv->r_lru, &resmap->m_lru);
}
static void __ocfs2_resv_trunc(struct ocfs2_alloc_reservation *resv)
{
resv->r_len = 0;
resv->r_start = 0;
}
static void ocfs2_resv_remove(struct ocfs2_reservation_map *resmap,
struct ocfs2_alloc_reservation *resv)
{
if (resv->r_flags & OCFS2_RESV_FLAG_INUSE) {
list_del_init(&resv->r_lru);
rb_erase(&resv->r_node, &resmap->m_reservations);
resv->r_flags &= ~OCFS2_RESV_FLAG_INUSE;
}
}
static void __ocfs2_resv_discard(struct ocfs2_reservation_map *resmap,
struct ocfs2_alloc_reservation *resv)
{
assert_spin_locked(&resv_lock);
__ocfs2_resv_trunc(resv);
/*
* last_len and last_start no longer make sense if
* we're changing the range of our allocations.
*/
resv->r_last_len = resv->r_last_start = 0;
ocfs2_resv_remove(resmap, resv);
}
/* does nothing if 'resv' is null */
void ocfs2_resv_discard(struct ocfs2_reservation_map *resmap,
struct ocfs2_alloc_reservation *resv)
{
if (resv) {
spin_lock(&resv_lock);
__ocfs2_resv_discard(resmap, resv);
spin_unlock(&resv_lock);
}
}
static void ocfs2_resmap_clear_all_resv(struct ocfs2_reservation_map *resmap)
{
struct rb_node *node;
struct ocfs2_alloc_reservation *resv;
assert_spin_locked(&resv_lock);
while ((node = rb_last(&resmap->m_reservations)) != NULL) {
resv = rb_entry(node, struct ocfs2_alloc_reservation, r_node);
__ocfs2_resv_discard(resmap, resv);
}
}
void ocfs2_resmap_restart(struct ocfs2_reservation_map *resmap,
unsigned int clen, char *disk_bitmap)
{
if (ocfs2_resmap_disabled(resmap))
return;
spin_lock(&resv_lock);
ocfs2_resmap_clear_all_resv(resmap);
resmap->m_bitmap_len = clen;
resmap->m_disk_bitmap = disk_bitmap;
spin_unlock(&resv_lock);
}
void ocfs2_resmap_uninit(struct ocfs2_reservation_map *resmap)
{
/* Does nothing for now. Keep this around for API symmetry */
}
static void ocfs2_resv_insert(struct ocfs2_reservation_map *resmap,
struct ocfs2_alloc_reservation *new)
{
struct rb_root *root = &resmap->m_reservations;
struct rb_node *parent = NULL;
struct rb_node **p = &root->rb_node;
struct ocfs2_alloc_reservation *tmp;
assert_spin_locked(&resv_lock);
mlog(0, "Insert reservation start: %u len: %u\n", new->r_start,
new->r_len);
while (*p) {
parent = *p;
tmp = rb_entry(parent, struct ocfs2_alloc_reservation, r_node);
if (new->r_start < tmp->r_start) {
p = &(*p)->rb_left;
/*
* This is a good place to check for
* overlapping reservations.
*/
BUG_ON(ocfs2_resv_end(new) >= tmp->r_start);
} else if (new->r_start > ocfs2_resv_end(tmp)) {
p = &(*p)->rb_right;
} else {
/* This should never happen! */
mlog(ML_ERROR, "Duplicate reservation window!\n");
BUG();
}
}
rb_link_node(&new->r_node, parent, p);
rb_insert_color(&new->r_node, root);
new->r_flags |= OCFS2_RESV_FLAG_INUSE;
ocfs2_resv_mark_lru(resmap, new);
ocfs2_check_resmap(resmap);
}
/**
* ocfs2_find_resv_lhs() - find the window which contains goal
* @resmap: reservation map to search
* @goal: which bit to search for
*
* If a window containing that goal is not found, we return the window
* which comes before goal. Returns NULL on empty rbtree or no window
* before goal.
*/
static struct ocfs2_alloc_reservation *
ocfs2_find_resv_lhs(struct ocfs2_reservation_map *resmap, unsigned int goal)
{
struct ocfs2_alloc_reservation *resv = NULL;
struct ocfs2_alloc_reservation *prev_resv = NULL;
struct rb_node *node = resmap->m_reservations.rb_node;
assert_spin_locked(&resv_lock);
if (!node)
return NULL;
node = rb_first(&resmap->m_reservations);
while (node) {
resv = rb_entry(node, struct ocfs2_alloc_reservation, r_node);
if (resv->r_start <= goal && ocfs2_resv_end(resv) >= goal)
break;
/* Check if we overshot the reservation just before goal? */
if (resv->r_start > goal) {
resv = prev_resv;
break;
}
prev_resv = resv;
node = rb_next(node);
}
return resv;
}
/*
* We are given a range within the bitmap, which corresponds to a gap
* inside the reservations tree (search_start, search_len). The range
* can be anything from the whole bitmap, to a gap between
* reservations.
*
* The start value of *rstart is insignificant.
*
* This function searches the bitmap range starting at search_start
* with length search_len for a set of contiguous free bits. We try
* to find up to 'wanted' bits, but can sometimes return less.
*
* Returns the length of allocation, 0 if no free bits are found.
*
* *cstart and *clen will also be populated with the result.
*/
static int ocfs2_resmap_find_free_bits(struct ocfs2_reservation_map *resmap,
unsigned int wanted,
unsigned int search_start,
unsigned int search_len,
unsigned int *rstart,
unsigned int *rlen)
{
void *bitmap = resmap->m_disk_bitmap;
unsigned int best_start, best_len = 0;
int offset, start, found;
mlog(0, "Find %u bits within range (%u, len %u) resmap len: %u\n",
wanted, search_start, search_len, resmap->m_bitmap_len);
found = best_start = best_len = 0;
start = search_start;
while ((offset = ocfs2_find_next_zero_bit(bitmap, resmap->m_bitmap_len,
start)) != -1) {
/* Search reached end of the region */
if (offset >= (search_start + search_len))
break;
if (offset == start) {
/* we found a zero */
found++;
/* move start to the next bit to test */
start++;
} else {
/* got a zero after some ones */
found = 1;
start = offset + 1;
}
if (found > best_len) {
best_len = found;
best_start = start - found;
}
if (found >= wanted)
break;
}
if (best_len == 0)
return 0;
if (best_len >= wanted)
best_len = wanted;
*rlen = best_len;
*rstart = best_start;
mlog(0, "Found start: %u len: %u\n", best_start, best_len);
return *rlen;
}
static void __ocfs2_resv_find_window(struct ocfs2_reservation_map *resmap,
struct ocfs2_alloc_reservation *resv,
unsigned int goal, unsigned int wanted)
{
struct rb_root *root = &resmap->m_reservations;
unsigned int gap_start, gap_end, gap_len;
struct ocfs2_alloc_reservation *prev_resv, *next_resv;
struct rb_node *prev, *next;
unsigned int cstart, clen;
unsigned int best_start = 0, best_len = 0;
/*
* Nasty cases to consider:
*
* - rbtree is empty
* - our window should be first in all reservations
* - our window should be last in all reservations
* - need to make sure we don't go past end of bitmap
*/
mlog(0, "resv start: %u resv end: %u goal: %u wanted: %u\n",
resv->r_start, ocfs2_resv_end(resv), goal, wanted);
assert_spin_locked(&resv_lock);
if (RB_EMPTY_ROOT(root)) {
/*
* Easiest case - empty tree. We can just take
* whatever window of free bits we want.
*/
mlog(0, "Empty root\n");
clen = ocfs2_resmap_find_free_bits(resmap, wanted, goal,
resmap->m_bitmap_len - goal,
&cstart, &clen);
/*
* This should never happen - the local alloc window
* will always have free bits when we're called.
*/
BUG_ON(goal == 0 && clen == 0);
if (clen == 0)
return;
resv->r_start = cstart;
resv->r_len = clen;
ocfs2_resv_insert(resmap, resv);
return;
}
prev_resv = ocfs2_find_resv_lhs(resmap, goal);
if (prev_resv == NULL) {
mlog(0, "Goal on LHS of leftmost window\n");
/*
* A NULL here means that the search code couldn't
* find a window that starts before goal.
*
* However, we can take the first window after goal,
* which is also by definition, the leftmost window in
* the entire tree. If we can find free bits in the
* gap between goal and the LHS window, then the
* reservation can safely be placed there.
*
* Otherwise we fall back to a linear search, checking
* the gaps in between windows for a place to
* allocate.
*/
next = rb_first(root);
next_resv = rb_entry(next, struct ocfs2_alloc_reservation,
r_node);
/*
* The search should never return such a window. (see
* comment above
*/
if (next_resv->r_start <= goal) {
mlog(ML_ERROR, "goal: %u next_resv: start %u len %u\n",
goal, next_resv->r_start, next_resv->r_len);
ocfs2_dump_resv(resmap);
BUG();
}
clen = ocfs2_resmap_find_free_bits(resmap, wanted, goal,
next_resv->r_start - goal,
&cstart, &clen);
if (clen) {
best_len = clen;
best_start = cstart;
if (best_len == wanted)
goto out_insert;
}
prev_resv = next_resv;
next_resv = NULL;
}
prev = &prev_resv->r_node;
/* Now we do a linear search for a window, starting at 'prev_rsv' */
while (1) {
next = rb_next(prev);
if (next) {
mlog(0, "One more resv found in linear search\n");
next_resv = rb_entry(next,
struct ocfs2_alloc_reservation,
r_node);
gap_start = ocfs2_resv_end(prev_resv) + 1;
gap_end = next_resv->r_start - 1;
gap_len = gap_end - gap_start + 1;
} else {
mlog(0, "No next node\n");
/*
* We're at the rightmost edge of the
* tree. See if a reservation between this
* window and the end of the bitmap will work.
*/
gap_start = ocfs2_resv_end(prev_resv) + 1;
gap_len = resmap->m_bitmap_len - gap_start;
gap_end = resmap->m_bitmap_len - 1;
}
/*
* No need to check this gap if we have already found
* a larger region of free bits.
*/
if (gap_len <= best_len)
goto next_resv;
clen = ocfs2_resmap_find_free_bits(resmap, wanted, gap_start,
gap_len, &cstart, &clen);
if (clen == wanted) {
best_len = clen;
best_start = cstart;
goto out_insert;
} else if (clen > best_len) {
best_len = clen;
best_start = cstart;
}
next_resv:
if (!next)
break;
prev = next;
prev_resv = rb_entry(prev, struct ocfs2_alloc_reservation,
r_node);
}
out_insert:
if (best_len) {
resv->r_start = best_start;
resv->r_len = best_len;
ocfs2_resv_insert(resmap, resv);
}
}
static void ocfs2_cannibalize_resv(struct ocfs2_reservation_map *resmap,
struct ocfs2_alloc_reservation *resv,
unsigned int wanted)
{
struct ocfs2_alloc_reservation *lru_resv;
int tmpwindow = !!(resv->r_flags & OCFS2_RESV_FLAG_TMP);
unsigned int min_bits;
if (!tmpwindow)
min_bits = ocfs2_resv_window_bits(resmap, resv) >> 1;
else
min_bits = wanted; /* We at know the temp window will use all
* of these bits */
/*
* Take the first reservation off the LRU as our 'target'. We
* don't try to be smart about it. There might be a case for
* searching based on size but I don't have enough data to be
* sure. --Mark (3/16/2010)
*/
lru_resv = list_first_entry(&resmap->m_lru,
struct ocfs2_alloc_reservation, r_lru);
mlog(0, "lru resv: start: %u len: %u end: %u\n", lru_resv->r_start,
lru_resv->r_len, ocfs2_resv_end(lru_resv));
/*
* Cannibalize (some or all) of the target reservation and
* feed it to the current window.
*/
if (lru_resv->r_len <= min_bits) {
/*
* Discard completely if size is less than or equal to a
* reasonable threshold - 50% of window bits for non temporary
* windows.
*/
resv->r_start = lru_resv->r_start;
resv->r_len = lru_resv->r_len;
__ocfs2_resv_discard(resmap, lru_resv);
} else {
unsigned int shrink;
if (tmpwindow)
shrink = min_bits;
else
shrink = lru_resv->r_len / 2;
lru_resv->r_len -= shrink;
resv->r_start = ocfs2_resv_end(lru_resv) + 1;
resv->r_len = shrink;
}
mlog(0, "Reservation now looks like: r_start: %u r_end: %u "
"r_len: %u r_last_start: %u r_last_len: %u\n",
resv->r_start, ocfs2_resv_end(resv), resv->r_len,
resv->r_last_start, resv->r_last_len);
ocfs2_resv_insert(resmap, resv);
}
static void ocfs2_resv_find_window(struct ocfs2_reservation_map *resmap,
struct ocfs2_alloc_reservation *resv,
unsigned int wanted)
{
unsigned int goal = 0;
BUG_ON(!ocfs2_resv_empty(resv));
/*
* Begin by trying to get a window as close to the previous
* one as possible. Using the most recent allocation as a
* start goal makes sense.
*/
if (resv->r_last_len) {
goal = resv->r_last_start + resv->r_last_len;
if (goal >= resmap->m_bitmap_len)
goal = 0;
}
__ocfs2_resv_find_window(resmap, resv, goal, wanted);
/* Search from last alloc didn't work, try once more from beginning. */
if (ocfs2_resv_empty(resv) && goal != 0)
__ocfs2_resv_find_window(resmap, resv, 0, wanted);
if (ocfs2_resv_empty(resv)) {
/*
* Still empty? Pull oldest one off the LRU, remove it from
* tree, put this one in it's place.
*/
ocfs2_cannibalize_resv(resmap, resv, wanted);
}
BUG_ON(ocfs2_resv_empty(resv));
}
int ocfs2_resmap_resv_bits(struct ocfs2_reservation_map *resmap,
struct ocfs2_alloc_reservation *resv,
int *cstart, int *clen)
{
unsigned int wanted = *clen;
if (resv == NULL || ocfs2_resmap_disabled(resmap))
return -ENOSPC;
spin_lock(&resv_lock);
/*
* We don't want to over-allocate for temporary
* windows. Otherwise, we run the risk of fragmenting the
* allocation space.
*/
wanted = ocfs2_resv_window_bits(resmap, resv);
if ((resv->r_flags & OCFS2_RESV_FLAG_TMP) || wanted < *clen)
wanted = *clen;
if (ocfs2_resv_empty(resv)) {
mlog(0, "empty reservation, find new window\n");
/*
* Try to get a window here. If it works, we must fall
* through and test the bitmap . This avoids some
* ping-ponging of windows due to non-reserved space
* being allocation before we initialize a window for
* that inode.
*/
ocfs2_resv_find_window(resmap, resv, wanted);
}
BUG_ON(ocfs2_resv_empty(resv));
*cstart = resv->r_start;
*clen = resv->r_len;
spin_unlock(&resv_lock);
return 0;
}
static void
ocfs2_adjust_resv_from_alloc(struct ocfs2_reservation_map *resmap,
struct ocfs2_alloc_reservation *resv,
unsigned int start, unsigned int end)
{
unsigned int rhs = 0;
unsigned int old_end = ocfs2_resv_end(resv);
BUG_ON(start != resv->r_start || old_end < end);
/*
* Completely used? We can remove it then.
*/
if (old_end == end) {
__ocfs2_resv_discard(resmap, resv);
return;
}
rhs = old_end - end;
/*
* This should have been trapped above.
*/
BUG_ON(rhs == 0);
resv->r_start = end + 1;
resv->r_len = old_end - resv->r_start + 1;
}
void ocfs2_resmap_claimed_bits(struct ocfs2_reservation_map *resmap,
struct ocfs2_alloc_reservation *resv,
u32 cstart, u32 clen)
{
unsigned int cend = cstart + clen - 1;
if (resmap == NULL || ocfs2_resmap_disabled(resmap))
return;
if (resv == NULL)
return;
BUG_ON(cstart != resv->r_start);
spin_lock(&resv_lock);
mlog(0, "claim bits: cstart: %u cend: %u clen: %u r_start: %u "
"r_end: %u r_len: %u, r_last_start: %u r_last_len: %u\n",
cstart, cend, clen, resv->r_start, ocfs2_resv_end(resv),
resv->r_len, resv->r_last_start, resv->r_last_len);
BUG_ON(cstart < resv->r_start);
BUG_ON(cstart > ocfs2_resv_end(resv));
BUG_ON(cend > ocfs2_resv_end(resv));
ocfs2_adjust_resv_from_alloc(resmap, resv, cstart, cend);
resv->r_last_start = cstart;
resv->r_last_len = clen;
/*
* May have been discarded above from
* ocfs2_adjust_resv_from_alloc().
*/
if (!ocfs2_resv_empty(resv))
ocfs2_resv_mark_lru(resmap, resv);
mlog(0, "Reservation now looks like: r_start: %u r_end: %u "
"r_len: %u r_last_start: %u r_last_len: %u\n",
resv->r_start, ocfs2_resv_end(resv), resv->r_len,
resv->r_last_start, resv->r_last_len);
ocfs2_check_resmap(resmap);
spin_unlock(&resv_lock);
}
