/*
* Copyright (C) 2012 Fusion-io All rights reserved.
* Copyright (C) 2012 Intel Corp. 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 v2 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.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 021110-1307, USA.
*/
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/bio.h>
#include <linux/slab.h>
#include <linux/buffer_head.h>
#include <linux/blkdev.h>
#include <linux/random.h>
#include <linux/iocontext.h>
#include <linux/capability.h>
#include <linux/ratelimit.h>
#include <linux/kthread.h>
#include <linux/raid/pq.h>
#include <linux/hash.h>
#include <linux/list_sort.h>
#include <linux/raid/xor.h>
#include <linux/vmalloc.h>
#include <asm/div64.h>
#include "compat.h"
#include "ctree.h"
#include "extent_map.h"
#include "disk-io.h"
#include "transaction.h"
#include "print-tree.h"
#include "volumes.h"
#include "raid56.h"
#include "async-thread.h"
#include "check-integrity.h"
#include "rcu-string.h"
/* set when additional merges to this rbio are not allowed */
#define RBIO_RMW_LOCKED_BIT 1
/*
* set when this rbio is sitting in the hash, but it is just a cache
* of past RMW
*/
#define RBIO_CACHE_BIT 2
/*
* set when it is safe to trust the stripe_pages for caching
*/
#define RBIO_CACHE_READY_BIT 3
#define RBIO_CACHE_SIZE 1024
struct btrfs_raid_bio {
struct btrfs_fs_info *fs_info;
struct btrfs_bio *bbio;
/*
* logical block numbers for the start of each stripe
* The last one or two are p/q. These are sorted,
* so raid_map[0] is the start of our full stripe
*/
u64 *raid_map;
/* while we're doing rmw on a stripe
* we put it into a hash table so we can
* lock the stripe and merge more rbios
* into it.
*/
struct list_head hash_list;
/*
* LRU list for the stripe cache
*/
struct list_head stripe_cache;
/*
* for scheduling work in the helper threads
*/
struct btrfs_work work;
/*
* bio list and bio_list_lock are used
* to add more bios into the stripe
* in hopes of avoiding the full rmw
*/
struct bio_list bio_list;
spinlock_t bio_list_lock;
/* also protected by the bio_list_lock, the
* plug list is used by the plugging code
* to collect partial bios while plugged. The
* stripe locking code also uses it to hand off
* the stripe lock to the next pending IO
*/
struct list_head plug_list;
/*
* flags that tell us if it is safe to
* merge with this bio
*/
unsigned long flags;
/* size of each individual stripe on disk */
int stripe_len;
/* number of data stripes (no p/q) */
int nr_data;
/*
* set if we're doing a parity rebuild
* for a read from higher up, which is handled
* differently from a parity rebuild as part of
* rmw
*/
int read_rebuild;
/* first bad stripe */
int faila;
/* second bad stripe (for raid6 use) */
int failb;
/*
* number of pages needed to represent the full
* stripe
*/
int nr_pages;
/*
* size of all the bios in the bio_list. This
* helps us decide if the rbio maps to a full
* stripe or not
*/
int bio_list_bytes;
atomic_t refs;
/*
* these are two arrays of pointers. We allocate the
* rbio big enough to hold them both and setup their
* locations when the rbio is allocated
*/
/* pointers to pages that we allocated for
* reading/writing stripes directly from the disk (including P/Q)
*/
struct page **stripe_pages;
/*
* pointers to the pages in the bio_list. Stored
* here for faster lookup
*/
struct page **bio_pages;
};
static int __raid56_parity_recover(struct btrfs_raid_bio *rbio);
static noinline void finish_rmw(struct btrfs_raid_bio *rbio);
static void rmw_work(struct btrfs_work *work);
static void read_rebuild_work(struct btrfs_work *work);
static void async_rmw_stripe(struct btrfs_raid_bio *rbio);
static void async_read_rebuild(struct btrfs_raid_bio *rbio);
static int fail_bio_stripe(struct btrfs_raid_bio *rbio, struct bio *bio);
static int fail_rbio_index(struct btrfs_raid_bio *rbio, int failed);
static void __free_raid_bio(struct btrfs_raid_bio *rbio);
static void index_rbio_pages(struct btrfs_raid_bio *rbio);
static int alloc_rbio_pages(struct btrfs_raid_bio *rbio);
/*
* the stripe hash table is used for locking, and to collect
* bios in hopes of making a full stripe
*/
int btrfs_alloc_stripe_hash_table(struct btrfs_fs_info *info)
{
struct btrfs_stripe_hash_table *table;
struct btrfs_stripe_hash_table *x;
struct btrfs_stripe_hash *cur;
struct btrfs_stripe_hash *h;
int num_entries = 1 << BTRFS_STRIPE_HASH_TABLE_BITS;
int i;
int table_size;
if (info->stripe_hash_table)
return 0;
/*
* The table is large, starting with order 4 and can go as high as
* order 7 in case lock debugging is turned on.
*
* Try harder to allocate and fallback to vmalloc to lower the chance
* of a failing mount.
*/
table_size = sizeof(*table) + sizeof(*h) * num_entries;
table = kzalloc(table_size, GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT);
if (!table) {
table = vzalloc(table_size);
if (!table)
return -ENOMEM;
}
spin_lock_init(&table->cache_lock);
INIT_LIST_HEAD(&table->stripe_cache);
h = table->table;
for (i = 0; i < num_entries; i++) {
cur = h + i;
INIT_LIST_HEAD(&cur->hash_list);
spin_lock_init(&cur->lock);
init_waitqueue_head(&cur->wait);
}
x = cmpxchg(&info->stripe_hash_table, NULL, table);
if (x) {
if (is_vmalloc_addr(x))
vfree(x);
else
kfree(x);
}
return 0;
}
/*
* caching an rbio means to copy anything from the
* bio_pages array into the stripe_pages array. We
* use the page uptodate bit in the stripe cache array
* to indicate if it has valid data
*
* once the caching is done, we set the cache ready
* bit.
*/
static void cache_rbio_pages(struct btrfs_raid_bio *rbio)
{
int i;
char *s;
char *d;
int ret;
ret = alloc_rbio_pages(rbio);
if (ret)
return;
for (i = 0; i < rbio->nr_pages; i++) {
if (!rbio->bio_pages[i])
continue;
s = kmap(rbio->bio_pages[i]);
d = kmap(rbio->stripe_pages[i]);
memcpy(d, s, PAGE_CACHE_SIZE);
kunmap(rbio->bio_pages[i]);
kunmap(rbio->stripe_pages[i]);
SetPageUptodate(rbio->stripe_pages[i]);
}
set_bit(RBIO_CACHE_READY_BIT, &rbio->flags);
}
/*
* we hash on the first logical address of the stripe
*/
static int rbio_bucket(struct btrfs_raid_bio *rbio)
{
u64 num = rbio->raid_map[0];
/*
* we shift down quite a bit. We're using byte
* addressing, and most of the lower bits are zeros.
* This tends to upset hash_64, and it consistently
* returns just one or two different values.
*
* shifting off the lower bits fixes things.
*/
return hash_64(num >> 16, BTRFS_STRIPE_HASH_TABLE_BITS);
}
/*
* stealing an rbio means taking all the uptodate pages from the stripe
* array in the source rbio and putting them into the destination rbio
*/
static void steal_rbio(struct btrfs_raid_bio *src, struct btrfs_raid_bio *dest)
{
int i;
struct page *s;
struct page *d;
if (!test_bit(RBIO_CACHE_READY_BIT, &src->flags))
return;
for (i = 0; i < dest->nr_pages; i++) {
s = src->stripe_pages[i];
if (!s || !PageUptodate(s)) {
continue;
}
d = dest->stripe_pages[i];
if (d)
__free_page(d);
dest->stripe_pages[i] = s;
src->stripe_pages[i] = NULL;
}
}
/*
* merging means we take the bio_list from the victim and
* splice it into the destination. The victim should
* be discarded afterwards.
*
* must be called with dest->rbio_list_lock held
*/
static void merge_rbio(struct btrfs_raid_bio *dest,
struct btrfs_raid_bio *victim)
{
bio_list_merge(&dest->bio_list, &victim->bio_list);
dest->bio_list_bytes += victim->bio_list_bytes;
bio_list_init(&victim->bio_list);
}
/*
* used to prune items that are in the cache. The caller
* must hold the hash table lock.
*/
static void __remove_rbio_from_cache(struct btrfs_raid_bio *rbio)
{
int bucket = rbio_bucket(rbio);
struct btrfs_stripe_hash_table *table;
struct btrfs_stripe_hash *h;
int freeit = 0;
/*
* check the bit again under the hash table lock.
*/
if (!test_bit(RBIO_CACHE_BIT, &rbio->flags))
return;
table = rbio->fs_info->stripe_hash_table;
h = table->table + bucket;
/* hold the lock for the bucket because we may be
* removing it from the hash table
*/
spin_lock(&h->lock);
/*
* hold the lock for the bio list because we need
* to make sure the bio list is empty
*/
spin_lock(&rbio->bio_list_lock);
if (test_and_clear_bit(RBIO_CACHE_BIT, &rbio->flags)) {
list_del_init(&rbio->stripe_cache);
table->cache_size -= 1;
freeit = 1;
/* if the bio list isn't empty, this rbio is
* still involved in an IO. We take it out
* of the cache list, and drop the ref that
* was held for the list.
*
* If the bio_list was empty, we also remove
* the rbio from the hash_table, and drop
* the corresponding ref
*/
if (bio_list_empty(&rbio->bio_list)) {
if (!list_empty(&rbio->hash_list)) {
list_del_init(&rbio->hash_list);
atomic_dec(&rbio->refs);
BUG_ON(!list_empty(&rbio->plug_list));
}
}
}
spin_unlock(&rbio->bio_list_lock);
spin_unlock(&h->lock);
if (freeit)
__free_raid_bio(rbio);
}
/*
* prune a given rbio from the cache
*/
static void remove_rbio_from_cache(struct btrfs_raid_bio *rbio)
{
struct btrfs_stripe_hash_table *table;
unsigned long flags;
if (!test_bit(RBIO_CACHE_BIT, &rbio->flags))
return;
table = rbio->fs_info->stripe_hash_table;
spin_lock_irqsave(&table->cache_lock, flags);
__remove_rbio_from_cache(rbio);
spin_unlock_irqrestore(&table->cache_lock, flags);
}
/*
* remove everything in the cache
*/
static void btrfs_clear_rbio_cache(struct btrfs_fs_info *info)
{
struct btrfs_stripe_hash_table *table;
unsigned long flags;
struct btrfs_raid_bio *rbio;
table = info->stripe_hash_table;
spin_lock_irqsave(&table->cache_lock, flags);
while (!list_empty(&table->stripe_cache)) {
rbio = list_entry(table->stripe_cache.next,
struct btrfs_raid_bio,
stripe_cache);
__remove_rbio_from_cache(rbio);
}
spin_unlock_irqrestore(&table->cache_lock, flags);
}
/*
* remove all cached entries and free the hash table
* used by unmount
*/
void btrfs_free_stripe_hash_table(struct btrfs_fs_info *info)
{
if (!info->stripe_hash_table)
return;
btrfs_clear_rbio_cache(info);
if (is_vmalloc_addr(info->stripe_hash_table))
vfree(info->stripe_hash_table);
else
kfree(info->stripe_hash_table);
info->stripe_hash_table = NULL;
}
/*
* insert an rbio into the stripe cache. It
* must have already been prepared by calling
* cache_rbio_pages
*
* If this rbio was already cached, it gets
* moved to the front of the lru.
*
* If the size of the rbio cache is too big, we
* prune an item.
*/
static void cache_rbio(struct btrfs_raid_bio *rbio)
{
struct btrfs_stripe_hash_table *table;
unsigned long flags;
if (!test_bit(RBIO_CACHE_READY_BIT, &rbio->flags))
return;
table = rbio->fs_info->stripe_hash_table;
spin_lock_irqsave(&table->cache_lock, flags);
spin_lock(&rbio->bio_list_lock);
/* bump our ref if we were not in the list before */
if (!test_and_set_bit(RBIO_CACHE_BIT, &rbio->flags))
atomic_inc(&rbio->refs);
if (!list_empty(&rbio->stripe_cache)){
list_move(&rbio->stripe_cache, &table->stripe_cache);
} else {
list_add(&rbio->stripe_cache, &table->stripe_cache);
table->cache_size += 1;
}
spin_unlock(&rbio->bio_list_lock);
if (table->cache_size > RBIO_CACHE_SIZE) {
struct btrfs_raid_bio *found;
found = list_entry(table->stripe_cache.prev,
struct btrfs_raid_bio,
stripe_cache);
if (found != rbio)
__remove_rbio_from_cache(found);
}
spin_unlock_irqrestore(&table->cache_lock, flags);
return;
}
/*
* helper function to run the xor_blocks api. It is only
* able to do MAX_XOR_BLOCKS at a time, so we need to
* loop through.
*/
static void run_xor(void **pages, int src_cnt, ssize_t len)
{
int src_off = 0;
int xor_src_cnt = 0;
void *dest = pages[src_cnt];
while(src_cnt > 0) {
xor_src_cnt = min(src_cnt, MAX_XOR_BLOCKS);
xor_blocks(xor_src_cnt, len, dest, pages + src_off);
src_cnt -= xor_src_cnt;
src_off += xor_src_cnt;
}
}
/*
* returns true if the bio list inside this rbio
* covers an entire stripe (no rmw required).
* Must be called with the bio list lock held, or
* at a time when you know it is impossible to add
* new bios into the list
*/
static int __rbio_is_full(struct btrfs_raid_bio *rbio)
{
unsigned long size = rbio->bio_list_bytes;
int ret = 1;
if (size != rbio->nr_data * rbio->stripe_len)
ret = 0;
BUG_ON(size > rbio->nr_data * rbio->stripe_len);
return ret;
}
static int rbio_is_full(struct btrfs_raid_bio *rbio)
{
unsigned long flags;
int ret;
spin_lock_irqsave(&rbio->bio_list_lock, flags);
ret = __rbio_is_full(rbio);
spin_unlock_irqrestore(&rbio->bio_list_lock, flags);
return ret;
}
/*
* returns 1 if it is safe to merge two rbios together.
* The merging is safe if the two rbios correspond to
* the same stripe and if they are both going in the same
* direction (read vs write), and if neither one is
* locked for final IO
*
* The caller is responsible for locking such that
* rmw_locked is safe to test
*/
static int rbio_can_merge(struct btrfs_raid_bio *last,
struct btrfs_raid_bio *cur)
{
if (test_bit(RBIO_RMW_LOCKED_BIT, &last->flags) ||
test_bit(RBIO_RMW_LOCKED_BIT, &cur->flags))
return 0;
/*
* we can't merge with cached rbios, since the
* idea is that when we merge the destination
* rbio is going to run our IO for us. We can
* steal from cached rbio's though, other functions
* handle that.
*/
if (test_bit(RBIO_CACHE_BIT, &last->flags) ||
test_bit(RBIO_CACHE_BIT, &cur->flags))
return 0;
if (last->raid_map[0] !=
cur->raid_map[0])
return 0;
/* reads can't merge with writes */
if (last->read_rebuild !=
cur->read_rebuild) {
return 0;
}
return 1;
}
/*
* helper to index into the pstripe
*/
static struct page *rbio_pstripe_page(struct btrfs_raid_bio *rbio, int index)
{
index += (rbio->nr_data * rbio->stripe_len) >> PAGE_CACHE_SHIFT;
return rbio->stripe_pages[index];
}
/*
* helper to index into the qstripe, returns null
* if there is no qstripe
*/
static struct page *rbio_qstripe_page(struct btrfs_raid_bio *rbio, int index)
{
if (rbio->nr_data + 1 == rbio->bbio->num_stripes)
return NULL;
index += ((rbio->nr_data + 1) * rbio->stripe_len) >>
PAGE_CACHE_SHIFT;
return rbio->stripe_pages[index];
}
/*
* The first stripe in the table for a logical address
* has the lock. rbios are added in one of three ways:
*
* 1) Nobody has the stripe locked yet. The rbio is given
* the lock and 0 is returned. The caller must start the IO
* themselves.
*
* 2) Someone has the stripe locked, but we're able to merge
* with the lock owner. The rbio is freed and the IO will
* start automatically along with the existing rbio. 1 is returned.
*
* 3) Someone has the stripe locked, but we're not able to merge.
* The rbio is added to the lock owner's plug list, or merged into
* an rbio already on the plug list. When the lock owner unlocks,
* the next rbio on the list is run and the IO is started automatically.
* 1 is returned
*
* If we return 0, the caller still owns the rbio and must continue with
* IO submission. If we return 1, the caller must assume the rbio has
* already been freed.
*/
static noinline int lock_stripe_add(struct btrfs_raid_bio *rbio)
{
int bucket = rbio_bucket(rbio);
struct btrfs_stripe_hash *h = rbio->fs_info->stripe_hash_table->table + bucket;
struct btrfs_raid_bio *cur;
struct btrfs_raid_bio *pending;
unsigned long flags;
DEFINE_WAIT(wait);
struct btrfs_raid_bio *freeit = NULL;
struct btrfs_raid_bio *cache_drop = NULL;
int ret = 0;
int walk = 0;
spin_lock_irqsave(&h->lock, flags);
list_for_each_entry(cur, &h->hash_list, hash_list) {
walk++;
if (cur->raid_map[0] == rbio->raid_map[0]) {
spin_lock(&cur->bio_list_lock);
/* can we steal this cached rbio's pages? */
if (bio_list_empty(&cur->bio_list) &&
list_empty(&cur->plug_list) &&
test_bit(RBIO_CACHE_BIT, &cur->flags) &&
!test_bit(RBIO_RMW_LOCKED_BIT, &cur->flags)) {
list_del_init(&cur->hash_list);
atomic_dec(&cur->refs);
steal_rbio(cur, rbio);
cache_drop = cur;
spin_unlock(&cur->bio_list_lock);
goto lockit;
}
/* can we merge into the lock owner? */
if (rbio_can_merge(cur, rbio)) {
merge_rbio(cur, rbio);
spin_unlock(&cur->bio_list_lock);
freeit = rbio;
ret = 1;
goto out;
}
/*
* we couldn't merge with the running
* rbio, see if we can merge with the
* pending ones. We don't have to
* check for rmw_locked because there
* is no way they are inside finish_rmw
* right now
*/
list_for_each_entry(pending, &cur->plug_list,
plug_list) {
if (rbio_can_merge(pending, rbio)) {
merge_rbio(pending, rbio);
spin_unlock(&cur->bio_list_lock);
freeit = rbio;
ret = 1;
goto out;
}
}
/* no merging, put us on the tail of the plug list,
* our rbio will be started with the currently
* running rbio unlocks
*/
list_add_tail(&rbio->plug_list, &cur->plug_list);
spin_unlock(&cur->bio_list_lock);
ret = 1;
goto out;
}
}
lockit:
atomic_inc(&rbio->refs);
list_add(&rbio->hash_list, &h->hash_list);
out:
spin_unlock_irqrestore(&h->lock, flags);
if (cache_drop)
remove_rbio_from_cache(cache_drop);
if (freeit)
__free_raid_bio(freeit);
return ret;
}
/*
* called as rmw or parity rebuild is completed. If the plug list has more
* rbios waiting for this stripe, the next one on the list will be started
*/
static noinline void unlock_stripe(struct btrfs_raid_bio *rbio)
{
int bucket;
struct btrfs_stripe_hash *h;
unsigned long flags;
int keep_cache = 0;
bucket = rbio_bucket(rbio);
h = rbio->fs_info->stripe_hash_table->table + bucket;
if (list_empty(&rbio->plug_list))
cache_rbio(rbio);
spin_lock_irqsave(&h->lock, flags);
spin_lock(&rbio->bio_list_lock);
if (!list_empty(&rbio->hash_list)) {
/*
* if we're still cached and there is no other IO
* to perform, just leave this rbio here for others
* to steal from later
*/
if (list_empty(&rbio->plug_list) &&
test_bit(RBIO_CACHE_BIT, &rbio->flags)) {
keep_cache = 1;
clear_bit(RBIO_RMW_LOCKED_BIT, &rbio->flags);
BUG_ON(!bio_list_empty(&rbio->bio_list));
goto done;
}
list_del_init(&rbio->hash_list);
atomic_dec(&rbio->refs);
/*
* we use the plug list to hold all the rbios
* waiting for the chance to lock this stripe.
* hand the lock over to one of them.
*/
if (!list_empty(&rbio->plug_list)) {
struct btrfs_raid_bio *next;
struct list_head *head = rbio->plug_list.next;
next = list_entry(head, struct btrfs_raid_bio,
plug_list);
list_del_init(&rbio->plug_list);
list_add(&next->hash_list, &h->hash_list);
atomic_inc(&next->refs);
spin_unlock(&rbio->bio_list_lock);
spin_unlock_irqrestore(&h->lock, flags);
if (next->read_rebuild)
async_read_rebuild(next);
else {
steal_rbio(rbio, next);
async_rmw_stripe(next);
}
goto done_nolock;
} else if (waitqueue_active(&h->wait)) {
spin_unlock(&rbio->bio_list_lock);
spin_unlock_irqrestore(&h->lock, flags);
wake_up(&h->wait);
goto done_nolock;
}
}
done:
spin_unlock(&rbio->bio_list_lock);
spin_unlock_irqrestore(&h->lock, flags);
done_nolock:
if (!keep_cache)
remove_rbio_from_cache(rbio);
}
static void __free_raid_bio(struct btrfs_raid_bio *rbio)
{
int i;
WARN_ON(atomic_read(&rbio->refs) < 0);
if (!atomic_dec_and_test(&rbio->refs))
return;
WARN_ON(!list_empty(&rbio->stripe_cache));
WARN_ON(!list_empty(&rbio->hash_list));
WARN_ON(!bio_list_empty(&rbio->bio_list));
for (i = 0; i < rbio->nr_pages; i++) {
if (rbio->stripe_pages[i]) {
__free_page(rbio->stripe_pages[i]);
rbio->stripe_pages[i] = NULL;
}
}
kfree(rbio->raid_map);
kfree(rbio->bbio);
kfree(rbio);
}
static void free_raid_bio(struct btrfs_raid_bio *rbio)
{
unlock_stripe(rbio);
__free_raid_bio(rbio);
}
/*
* this frees the rbio and runs through all the bios in the
* bio_list and calls end_io on them
*/
static void rbio_orig_end_io(struct btrfs_raid_bio *rbio, int err, int uptodate)
{
struct bio *cur = bio_list_get(&rbio->bio_list);
struct bio *next;
free_raid_bio(rbio);
while (cur) {
next = cur->bi_next;
cur->bi_next = NULL;
if (uptodate)
set_bit(BIO_UPTODATE, &cur->bi_flags);
bio_endio(cur, err);
cur = next;
}
}
/*
* end io function used by finish_rmw. When we finally
* get here, we've written a full stripe
*/
static void raid_write_end_io(struct bio *bio, int err)
{
struct btrfs_raid_bio *rbio = bio->bi_private;
if (err)
fail_bio_stripe(rbio, bio);
bio_put(bio);
if (!atomic_dec_and_test(&rbio->bbio->stripes_pending))
return;
err = 0;
/* OK, we have read all the stripes we need to. */
if (atomic_read(&rbio->bbio->error) > rbio->bbio->max_errors)
err = -EIO;
rbio_orig_end_io(rbio, err, 0);
return;
}
/*
* the read/modify/write code wants to use the original bio for
* any pages it included, and then use the rbio for everything
* else. This function decides if a given index (stripe number)
* and page number in that stripe fall inside the original bio
* or the rbio.
*
* if you set bio_list_only, you'll get a NULL back for any ranges
* that are outside the bio_list
*
* This doesn't take any refs on anything, you get a bare page pointer
* and the caller must bump refs as required.
*
* You must call index_rbio_pages once before you can trust
* the answers from this function.
*/
static struct page *page_in_rbio(struct btrfs_raid_bio *rbio,
int index, int pagenr, int bio_list_only)
{
int chunk_page;
struct page *p = NULL;
chunk_page = index * (rbio->stripe_len >> PAGE_SHIFT) + pagenr;
spin_lock_irq(&rbio->bio_list_lock);
p = rbio->bio_pages[chunk_page];
spin_unlock_irq(&rbio->bio_list_lock);
if (p || bio_list_only)
return p;
return rbio->stripe_pages[chunk_page];
}
/*
* number of pages we need for the entire stripe across all the
* drives
*/
static unsigned long rbio_nr_pages(unsigned long stripe_len, int nr_stripes)
{
unsigned long nr = stripe_len * nr_stripes;
return (nr + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
}
/*
* allocation and initial setup for the btrfs_raid_bio. Not
* this does not allocate any pages for rbio->pages.
*/
static struct btrfs_raid_bio *alloc_rbio(struct btrfs_root *root,
struct btrfs_bio *bbio, u64 *raid_map,
u64 stripe_len)
{
struct btrfs_raid_bio *rbio;
int nr_data = 0;
int num_pages = rbio_nr_pages(stripe_len, bbio->num_stripes);
void *p;
rbio = kzalloc(sizeof(*rbio) + num_pages * sizeof(struct page *) * 2,
GFP_NOFS);
if (!rbio) {
kfree(raid_map);
kfree(bbio);
return ERR_PTR(-ENOMEM);
}
bio_list_init(&rbio->bio_list);
INIT_LIST_HEAD(&rbio->plug_list);
spin_lock_init(&rbio->bio_list_lock);
INIT_LIST_HEAD(&rbio->stripe_cache);
INIT_LIST_HEAD(&rbio->hash_list);
rbio->bbio = bbio;
rbio->raid_map = raid_map;
rbio->fs_info = root->fs_info;
rbio->stripe_len = stripe_len;
rbio->nr_pages = num_pages;
rbio->faila = -1;
rbio->failb = -1;
atomic_set(&rbio->refs, 1);
/*
* the stripe_pages and bio_pages array point to the extra
* memory we allocated past the end of the rbio
*/
p = rbio + 1;
rbio->stripe_pages = p;
rbio->bio_pages = p + sizeof(struct page *) * num_pages;
if (raid_map[bbio->num_stripes - 1] == RAID6_Q_STRIPE)
nr_data = bbio->num_stripes - 2;
else
nr_data = bbio->num_stripes - 1;
rbio->nr_data = nr_data;
return rbio;
}
/* allocate pages for all the stripes in the bio, including parity */
static int alloc_rbio_pages(struct btrfs_raid_bio *rbio)
{
int i;
struct page *page;
for (i = 0; i < rbio->nr_pages; i++) {
if (rbio->stripe_pages[i])
continue;
page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
if (!page)
return -ENOMEM;
rbio->stripe_pages[i] = page;
ClearPageUptodate(page);
}
return 0;
}
/* allocate pages for just the p/q stripes */
static int alloc_rbio_parity_pages(struct btrfs_raid_bio *rbio)
{
int i;
struct page *page;
i = (rbio->nr_data * rbio->stripe_len) >> PAGE_CACHE_SHIFT;
for (; i < rbio->nr_pages; i++) {
if (rbio->stripe_pages[i])
continue;
page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
if (!page)
return -ENOMEM;
rbio->stripe_pages[i] = page;
}
return 0;
}
/*
* add a single page from a specific stripe into our list of bios for IO
* this will try to merge into existing bios if possible, and returns
* zero if all went well.
*/
static int rbio_add_io_page(struct btrfs_raid_bio *rbio,
struct bio_list *bio_list,
struct page *page,
int stripe_nr,
unsigned long page_index,
unsigned long bio_max_len)
{
struct bio *last = bio_list->tail;
u64 last_end = 0;
int ret;
struct bio *bio;
struct btrfs_bio_stripe *stripe;
u64 disk_start;
stripe = &rbio->bbio->stripes[stripe_nr];
disk_start = stripe->physical + (page_index << PAGE_CACHE_SHIFT);
/* if the device is missing, just fail this stripe */
if (!stripe->dev->bdev)
return fail_rbio_index(rbio, stripe_nr);
/* see if we can add this page onto our existing bio */
if (last) {
last_end = (u64)last->bi_sector << 9;
last_end += last->bi_size;
/*
* we can't merge these if they are from different
* devices or if they are not contiguous
*/
if (last_end == disk_start && stripe->dev->bdev &&
test_bit(BIO_UPTODATE, &last->bi_flags) &&
last->bi_bdev == stripe->dev->bdev) {
ret = bio_add_page(last, page, PAGE_CACHE_SIZE, 0);
if (ret == PAGE_CACHE_SIZE)
return 0;
}
}
/* put a new bio on the list */
bio = btrfs_io_bio_alloc(GFP_NOFS, bio_max_len >> PAGE_SHIFT?:1);
if (!bio)
return -ENOMEM;
bio->bi_size = 0;
bio->bi_bdev = stripe->dev->bdev;
bio->bi_sector = disk_start >> 9;
set_bit(BIO_UPTODATE, &bio->bi_flags);
bio_add_page(bio, page, PAGE_CACHE_SIZE, 0);
bio_list_add(bio_list, bio);
return 0;
}
/*
* while we're doing the read/modify/write cycle, we could
* have errors in reading pages off the disk. This checks
* for errors and if we're not able to read the page it'll
* trigger parity reconstruction. The rmw will be finished
* after we've reconstructed the failed stripes
*/
static void validate_rbio_for_rmw(struct btrfs_raid_bio *rbio)
{
if (rbio->faila >= 0 || rbio->failb >= 0) {
BUG_ON(rbio->faila == rbio->bbio->num_stripes - 1);
__raid56_parity_recover(rbio);
} else {
finish_rmw(rbio);
}
}
/*
* these are just the pages from the rbio array, not from anything
* the FS sent down to us
*/
static struct page *rbio_stripe_page(struct btrfs_raid_bio *rbio, int stripe, int page)
{
int index;
index = stripe * (rbio->stripe_len >> PAGE_CACHE_SHIFT);
index += page;
return rbio->stripe_pages[index];
}
/*
* helper function to walk our bio list and populate the bio_pages array with
* the result. This seems expensive, but it is faster than constantly
* searching through the bio list as we setup the IO in finish_rmw or stripe
* reconstruction.
*
* This must be called before you trust the answers from page_in_rbio
*/
static void index_rbio_pages(struct btrfs_raid_bio *rbio)
{
struct bio *bio;
u64 start;
unsigned long stripe_offset;
unsigned long page_index;
struct page *p;
int i;
spin_lock_irq(&rbio->bio_list_lock);
bio_list_for_each(bio, &rbio->bio_list) {
start = (u64)bio->bi_sector << 9;
stripe_offset = start - rbio->raid_map[0];
page_index = stripe_offset >> PAGE_CACHE_SHIFT;
for (i = 0; i < bio->bi_vcnt; i++) {
p = bio->bi_io_vec[i].bv_page;
rbio->bio_pages[page_index + i] = p;
}
}
spin_unlock_irq(&rbio->bio_list_lock);
}
/*
* this is called from one of two situations. We either
* have a full stripe from the higher layers, or we've read all
* the missing bits off disk.
*
* This will calculate the parity and then send down any
* changed blocks.
*/
static noinline void finish_rmw(struct btrfs_raid_bio *rbio)
{
struct btrfs_bio *bbio = rbio->bbio;
void *pointers[bbio->num_stripes];
int stripe_len = rbio->stripe_len;
int nr_data = rbio->nr_data;
int stripe;
int pagenr;
int p_stripe = -1;
int q_stripe = -1;
struct bio_list bio_list;
struct bio *bio;
int pages_per_stripe = stripe_len >> PAGE_CACHE_SHIFT;
int ret;
bio_list_init(&bio_list);
if (bbio->num_stripes - rbio->nr_data == 1) {
p_stripe = bbio->num_stripes - 1;
} else if (bbio->num_stripes - rbio->nr_data == 2) {
p_stripe = bbio->num_stripes - 2;
q_stripe = bbio->num_stripes - 1;
} else {
BUG();
}
/* at this point we either have a full stripe,
* or we've read the full stripe from the drive.
* recalculate the parity and write the new results.
*
* We're not allowed to add any new bios to the
* bio list here, anyone else that wants to
* change this stripe needs to do their own rmw.
*/
spin_lock_irq(&rbio->bio_list_lock);
set_bit(RBIO_RMW_LOCKED_BIT, &rbio->flags);
spin_unlock_irq(&rbio->bio_list_lock);
atomic_set(&rbio->bbio->error, 0);
/*
* now that we've set rmw_locked, run through the
* bio list one last time and map the page pointers
*
* We don't cache full rbios because we're assuming
* the higher layers are unlikely to use this area of
* the disk again soon. If they do use it again,
* hopefully they will send another full bio.
*/
index_rbio_pages(rbio);
if (!rbio_is_full(rbio))
cache_rbio_pages(rbio);
else
clear_bit(RBIO_CACHE_READY_BIT, &rbio->flags);
for (pagenr = 0; pagenr < pages_per_stripe; pagenr++) {
struct page *p;
/* first collect one page from each data stripe */
for (stripe = 0; stripe < nr_data; stripe++) {
p = page_in_rbio(rbio, stripe, pagenr, 0);
pointers[stripe] = kmap(p);
}
/* then add the parity stripe */
p = rbio_pstripe_page(rbio, pagenr);
SetPageUptodate(p);
pointers[stripe++] = kmap(p);
if (q_stripe != -1) {
/*
* raid6, add the qstripe and call the
* library function to fill in our p/q
*/
p = rbio_qstripe_page(rbio, pagenr);
SetPageUptodate(p);
pointers[stripe++] = kmap(p);
raid6_call.gen_syndrome(bbio->num_stripes, PAGE_SIZE,
pointers);
} else {
/* raid5 */
memcpy(pointers[nr_data], pointers[0], PAGE_SIZE);
run_xor(pointers + 1, nr_data - 1, PAGE_CACHE_SIZE);
}
for (stripe = 0; stripe < bbio->num_stripes; stripe++)
kunmap(page_in_rbio(rbio, stripe, pagenr, 0));
}
/*
* time to start writing. Make bios for everything from the
* higher layers (the bio_list in our rbio) and our p/q. Ignore
* everything else.
*/
for (stripe = 0; stripe < bbio->num_stripes; stripe++) {
for (pagenr = 0; pagenr < pages_per_stripe; pagenr++) {
struct page *page;
if (stripe < rbio->nr_data) {
page = page_in_rbio(rbio, stripe, pagenr, 1);
if (!page)
continue;
} else {
page = rbio_stripe_page(rbio, stripe, pagenr);
}
ret = rbio_add_io_page(rbio, &bio_list,
page, stripe, pagenr, rbio->stripe_len);
if (ret)
goto cleanup;
}
}
atomic_set(&bbio->stripes_pending, bio_list_size(&bio_list));
BUG_ON(atomic_read(&bbio->stripes_pending) == 0);
while (1) {
bio = bio_list_pop(&bio_list);
if (!bio)
break;
bio->bi_private = rbio;
bio->bi_end_io = raid_write_end_io;
BUG_ON(!test_bit(BIO_UPTODATE, &bio->bi_flags));
submit_bio(WRITE, bio);
}
return;
cleanup:
rbio_orig_end_io(rbio, -EIO, 0);
}
/*
* helper to find the stripe number for a given bio. Used to figure out which
* stripe has failed. This expects the bio to correspond to a physical disk,
* so it looks up based on physical sector numbers.
*/
static int find_bio_stripe(struct btrfs_raid_bio *rbio,
struct bio *bio)
{
u64 physical = bio->bi_sector;
u64 stripe_start;
int i;
struct btrfs_bio_stripe *stripe;
physical <<= 9;
for (i = 0; i < rbio->bbio->num_stripes; i++) {
stripe = &rbio->bbio->stripes[i];
stripe_start = stripe->physical;
if (physical >= stripe_start &&
physical < stripe_start + rbio->stripe_len) {
return i;
}
}
return -1;
}
/*
* helper to find the stripe number for a given
* bio (before mapping). Used to figure out which stripe has
* failed. This looks up based on logical block numbers.
*/
static int find_logical_bio_stripe(struct btrfs_raid_bio *rbio,
struct bio *bio)
{
u64 logical = bio->bi_sector;
u64 stripe_start;
int i;
logical <<= 9;
for (i = 0; i < rbio->nr_data; i++) {
stripe_start = rbio->raid_map[i];
if (logical >= stripe_start &&
logical < stripe_start + rbio->stripe_len) {
return i;
}
}
return -1;
}
/*
* returns -EIO if we had too many failures
*/
static int fail_rbio_index(struct btrfs_raid_bio *rbio, int failed)
{
unsigned long flags;
int ret = 0;
spin_lock_irqsave(&rbio->bio_list_lock, flags);
/* we already know this stripe is bad, move on */
if (rbio->faila == failed || rbio->failb == failed)
goto out;
if (rbio->faila == -1) {
/* first failure on this rbio */
rbio->faila = failed;
atomic_inc(&rbio->bbio->error);
} else if (rbio->failb == -1) {
/* second failure on this rbio */
rbio->failb = failed;
atomic_inc(&rbio->bbio->error);
} else {
ret = -EIO;
}
out:
spin_unlock_irqrestore(&rbio->bio_list_lock, flags);
return ret;
}
/*
* helper to fail a stripe based on a physical disk
* bio.
*/
static int fail_bio_stripe(struct btrfs_raid_bio *rbio,
struct bio *bio)
{
int failed = find_bio_stripe(rbio, bio);
if (failed < 0)
return -EIO;
return fail_rbio_index(rbio, failed);
}
/*
* this sets each page in the bio uptodate. It should only be used on private
* rbio pages, nothing that comes in from the higher layers
*/
static void set_bio_pages_uptodate(struct bio *bio)
{
int i;
struct page *p;
for (i = 0; i < bio->bi_vcnt; i++) {
p = bio->bi_io_vec[i].bv_page;
SetPageUptodate(p);
}
}
/*
* end io for the read phase of the rmw cycle. All the bios here are physical
* stripe bios we've read from the disk so we can recalculate the parity of the
* stripe.
*
* This will usually kick off finish_rmw once all the bios are read in, but it
* may trigger parity reconstruction if we had any errors along the way
*/
static void raid_rmw_end_io(struct bio *bio, int err)
{
struct btrfs_raid_bio *rbio = bio->bi_private;
if (err)
fail_bio_stripe(rbio, bio);
else
set_bio_pages_uptodate(bio);
bio_put(bio);
if (!atomic_dec_and_test(&rbio->bbio->stripes_pending))
return;
err = 0;
if (atomic_read(&rbio->bbio->error) > rbio->bbio->max_errors)
goto cleanup;
/*
* this will normally call finish_rmw to start our write
* but if there are any failed stripes we'll reconstruct
* from parity first
*/
validate_rbio_for_rmw(rbio);
return;
cleanup:
rbio_orig_end_io(rbio, -EIO, 0);
}
static void async_rmw_stripe(struct btrfs_raid_bio *rbio)
{
rbio->work.flags = 0;
rbio->work.func = rmw_work;
btrfs_queue_worker(&rbio->fs_info->rmw_workers,
&rbio->work);
}
static void async_read_rebuild(struct btrfs_raid_bio *rbio)
{
rbio->work.flags = 0;
rbio->work.func = read_rebuild_work;
btrfs_queue_worker(&rbio->fs_info->rmw_workers,
&rbio->work);
}
/*
* the stripe must be locked by the caller. It will
* unlock after all the writes are done
*/
static int raid56_rmw_stripe(struct btrfs_raid_bio *rbio)
{
int bios_to_read = 0;
struct btrfs_bio *bbio = rbio->bbio;
struct bio_list bio_list;
int ret;
int nr_pages = (rbio->stripe_len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
int pagenr;
int stripe;
struct bio *bio;
bio_list_init(&bio_list);
ret = alloc_rbio_pages(rbio);
if (ret)
goto cleanup;
index_rbio_pages(rbio);
atomic_set(&rbio->bbio->error, 0);
/*
* build a list of bios to read all the missing parts of this
* stripe
*/
for (stripe = 0; stripe < rbio->nr_data; stripe++) {
for (pagenr = 0; pagenr < nr_pages; pagenr++) {
struct page *page;
/*
* we want to find all the pages missing from
* the rbio and read them from the disk. If
* page_in_rbio finds a page in the bio list
* we don't need to read it off the stripe.
*/
page = page_in_rbio(rbio, stripe, pagenr, 1);
if (page)
continue;
page = rbio_stripe_page(rbio, stripe, pagenr);
/*
* the bio cache may have handed us an uptodate
* page. If so, be happy and use it
*/
if (PageUptodate(page))
continue;
ret = rbio_add_io_page(rbio, &bio_list, page,
stripe, pagenr, rbio->stripe_len);
if (ret)
goto cleanup;
}
}
bios_to_read = bio_list_size(&bio_list);
if (!bios_to_read) {
/*
* this can happen if others have merged with
* us, it means there is nothing left to read.
* But if there are missing devices it may not be
* safe to do the full stripe write yet.
*/
goto finish;
}
/*
* the bbio may be freed once we submit the last bio. Make sure
* not to touch it after that
*/
atomic_set(&bbio->stripes_pending, bios_to_read);
while (1) {
bio = bio_list_pop(&bio_list);
if (!bio)
break;
bio->bi_private = rbio;
bio->bi_end_io = raid_rmw_end_io;
btrfs_bio_wq_end_io(rbio->fs_info, bio,
BTRFS_WQ_ENDIO_RAID56);
BUG_ON(!test_bit(BIO_UPTODATE, &bio->bi_flags));
submit_bio(READ, bio);
}
/* the actual write will happen once the reads are done */
return 0;
cleanup:
rbio_orig_end_io(rbio, -EIO, 0);
return -EIO;
finish:
validate_rbio_for_rmw(rbio);
return 0;
}
/*
* if the upper layers pass in a full stripe, we thank them by only allocating
* enough pages to hold the parity, and sending it all down quickly.
*/
static int full_stripe_write(struct btrfs_raid_bio *rbio)
{
int ret;
ret = alloc_rbio_parity_pages(rbio);
if (ret)
return ret;
ret = lock_stripe_add(rbio);
if (ret == 0)
finish_rmw(rbio);
return 0;
}
/*
* partial stripe writes get handed over to async helpers.
* We're really hoping to merge a few more writes into this
* rbio before calculating new parity
*/
static int partial_stripe_write(struct btrfs_raid_bio *rbio)
{
int ret;
ret = lock_stripe_add(rbio);
if (ret == 0)
async_rmw_stripe(rbio);
return 0;
}
/*
* sometimes while we were reading from the drive to
* recalculate parity, enough new bios come into create
* a full stripe. So we do a check here to see if we can
* go directly to finish_rmw
*/
static int __raid56_parity_write(struct btrfs_raid_bio *rbio)
{
/* head off into rmw land if we don't have a full stripe */
if (!rbio_is_full(rbio))
return partial_stripe_write(rbio);
return full_stripe_write(rbio);
}
/*
* We use plugging call backs to collect full stripes.
* Any time we get a partial stripe write while plugged
* we collect it into a list. When the unplug comes down,
* we sort the list by logical block number and merge
* everything we can into the same rbios
*/
struct btrfs_plug_cb {
struct blk_plug_cb cb;
struct btrfs_fs_info *info;
struct list_head rbio_list;
struct btrfs_work work;
};
/*
* rbios on the plug list are sorted for easier merging.
*/
static int plug_cmp(void *priv, struct list_head *a, struct list_head *b)
{
struct btrfs_raid_bio *ra = container_of(a, struct btrfs_raid_bio,
plug_list);
struct btrfs_raid_bio *rb = container_of(b, struct btrfs_raid_bio,
plug_list);
u64 a_sector = ra->bio_list.head->bi_sector;
u64 b_sector = rb->bio_list.head->bi_sector;
if (a_sector < b_sector)
return -1;
if (a_sector > b_sector)
return 1;
return 0;
}
static void run_plug(struct btrfs_plug_cb *plug)
{
struct btrfs_raid_bio *cur;
struct btrfs_raid_bio *last = NULL;
/*
* sort our plug list then try to merge
* everything we can in hopes of creating full
* stripes.
*/
list_sort(NULL, &plug->rbio_list, plug_cmp);
while (!list_empty(&plug->rbio_list)) {
cur = list_entry(plug->rbio_list.next,
struct btrfs_raid_bio, plug_list);
list_del_init(&cur->plug_list);
if (rbio_is_full(cur)) {
/* we have a full stripe, send it down */
full_stripe_write(cur);
continue;
}
if (last) {
if (rbio_can_merge(last, cur)) {
merge_rbio(last, cur);
__free_raid_bio(cur);
continue;
}
__raid56_parity_write(last);
}
last = cur;
}
if (last) {
__raid56_parity_write(last);
}
kfree(plug);
}
/*
* if the unplug comes from schedule, we have to push the
* work off to a helper thread
*/
static void unplug_work(struct btrfs_work *work)
{
struct btrfs_plug_cb *plug;
plug = container_of(work, struct btrfs_plug_cb, work);
run_plug(plug);
}
static void btrfs_raid_unplug(struct blk_plug_cb *cb, bool from_schedule)
{
struct btrfs_plug_cb *plug;
plug = container_of(cb, struct btrfs_plug_cb, cb);
if (from_schedule) {
plug->work.flags = 0;
plug->work.func = unplug_work;
btrfs_queue_worker(&plug->info->rmw_workers,
&plug->work);
return;
}
run_plug(plug);
}
/*
* our main entry point for writes from the rest of the FS.
*/
int raid56_parity_write(struct btrfs_root *root, struct bio *bio,
struct btrfs_bio *bbio, u64 *raid_map,
u64 stripe_len)
{
struct btrfs_raid_bio *rbio;
struct btrfs_plug_cb *plug = NULL;
struct blk_plug_cb *cb;
rbio = alloc_rbio(root, bbio, raid_map, stripe_len);
if (IS_ERR(rbio)) {
kfree(raid_map);
kfree(bbio);
return PTR_ERR(rbio);
}
bio_list_add(&rbio->bio_list, bio);
rbio->bio_list_bytes = bio->bi_size;
/*
* don't plug on full rbios, just get them out the door
* as quickly as we can
*/
if (rbio_is_full(rbio))
return full_stripe_write(rbio);
cb = blk_check_plugged(btrfs_raid_unplug, root->fs_info,
sizeof(*plug));
if (cb) {
plug = container_of(cb, struct btrfs_plug_cb, cb);
if (!plug->info) {
plug->info = root->fs_info;
INIT_LIST_HEAD(&plug->rbio_list);
}
list_add_tail(&rbio->plug_list, &plug->rbio_list);
} else {
return __raid56_parity_write(rbio);
}
return 0;
}
/*
* all parity reconstruction happens here. We've read in everything
* we can find from the drives and this does the heavy lifting of
* sorting the good from the bad.
*/
static void __raid_recover_end_io(struct btrfs_raid_bio *rbio)
{
int pagenr, stripe;
void **pointers;
int faila = -1, failb = -1;
int nr_pages = (rbio->stripe_len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
struct page *page;
int err;
int i;
pointers = kzalloc(rbio->bbio->num_stripes * sizeof(void *),
GFP_NOFS);
if (!pointers) {
err = -ENOMEM;
goto cleanup_io;
}
faila = rbio->faila;
failb = rbio->failb;
if (rbio->read_rebuild) {
spin_lock_irq(&rbio->bio_list_lock);
set_bit(RBIO_RMW_LOCKED_BIT, &rbio->flags);
spin_unlock_irq(&rbio->bio_list_lock);
}
index_rbio_pages(rbio);
for (pagenr = 0; pagenr < nr_pages; pagenr++) {
/* setup our array of pointers with pages
* from each stripe
*/
for (stripe = 0; stripe < rbio->bbio->num_stripes; stripe++) {
/*
* if we're rebuilding a read, we have to use
* pages from the bio list
*/
if (rbio->read_rebuild &&
(stripe == faila || stripe == failb)) {
page = page_in_rbio(rbio, stripe, pagenr, 0);
} else {
page = rbio_stripe_page(rbio, stripe, pagenr);
}
pointers[stripe] = kmap(page);
}
/* all raid6 handling here */
if (rbio->raid_map[rbio->bbio->num_stripes - 1] ==
RAID6_Q_STRIPE) {
/*
* single failure, rebuild from parity raid5
* style
*/
if (failb < 0) {
if (faila == rbio->nr_data) {
/*
* Just the P stripe has failed, without
* a bad data or Q stripe.
* TODO, we should redo the xor here.
*/
err = -EIO;
goto cleanup;
}
/*
* a single failure in raid6 is rebuilt
* in the pstripe code below
*/
goto pstripe;
}
/* make sure our ps and qs are in order */
if (faila > failb) {
int tmp = failb;
failb = faila;
faila = tmp;
}
/* if the q stripe is failed, do a pstripe reconstruction
* from the xors.
* If both the q stripe and the P stripe are failed, we're
* here due to a crc mismatch and we can't give them the
* data they want
*/
if (rbio->raid_map[failb] == RAID6_Q_STRIPE) {
if (rbio->raid_map[faila] == RAID5_P_STRIPE) {
err = -EIO;
goto cleanup;
}
/*
* otherwise we have one bad data stripe and
* a good P stripe. raid5!
*/
goto pstripe;
}
if (rbio->raid_map[failb] == RAID5_P_STRIPE) {
raid6_datap_recov(rbio->bbio->num_stripes,
PAGE_SIZE, faila, pointers);
} else {
raid6_2data_recov(rbio->bbio->num_stripes,
PAGE_SIZE, faila, failb,
pointers);
}
} else {
void *p;
/* rebuild from P stripe here (raid5 or raid6) */
BUG_ON(failb != -1);
pstripe:
/* Copy parity block into failed block to start with */
memcpy(pointers[faila],
pointers[rbio->nr_data],
PAGE_CACHE_SIZE);
/* rearrange the pointer array */
p = pointers[faila];
for (stripe = faila; stripe < rbio->nr_data - 1; stripe++)
pointers[stripe] = pointers[stripe + 1];
pointers[rbio->nr_data - 1] = p;
/* xor in the rest */
run_xor(pointers, rbio->nr_data - 1, PAGE_CACHE_SIZE);
}
/* if we're doing this rebuild as part of an rmw, go through
* and set all of our private rbio pages in the
* failed stripes as uptodate. This way finish_rmw will
* know they can be trusted. If this was a read reconstruction,
* other endio functions will fiddle the uptodate bits
*/
if (!rbio->read_rebuild) {
for (i = 0; i < nr_pages; i++) {
if (faila != -1) {
page = rbio_stripe_page(rbio, faila, i);
SetPageUptodate(page);
}
if (failb != -1) {
page = rbio_stripe_page(rbio, failb, i);
SetPageUptodate(page);
}
}
}
for (stripe = 0; stripe < rbio->bbio->num_stripes; stripe++) {
/*
* if we're rebuilding a read, we have to use
* pages from the bio list
*/
if (rbio->read_rebuild &&
(stripe == faila || stripe == failb)) {
page = page_in_rbio(rbio, stripe, pagenr, 0);
} else {
page = rbio_stripe_page(rbio, stripe, pagenr);
}
kunmap(page);
}
}
err = 0;
cleanup:
kfree(pointers);
cleanup_io:
if (rbio->read_rebuild) {
if (err == 0)
cache_rbio_pages(rbio);
else
clear_bit(RBIO_CACHE_READY_BIT, &rbio->flags);
rbio_orig_end_io(rbio, err, err == 0);
} else if (err == 0) {
rbio->faila = -1;
rbio->failb = -1;
finish_rmw(rbio);
} else {
rbio_orig_end_io(rbio, err, 0);
}
}
/*
* This is called only for stripes we've read from disk to
* reconstruct the parity.
*/
static void raid_recover_end_io(struct bio *bio, int err)
{
struct btrfs_raid_bio *rbio = bio->bi_private;
/*
* we only read stripe pages off the disk, set them
* up to date if there were no errors
*/
if (err)
fail_bio_stripe(rbio, bio);
else
set_bio_pages_uptodate(bio);
bio_put(bio);
if (!atomic_dec_and_test(&rbio->bbio->stripes_pending))
return;
if (atomic_read(&rbio->bbio->error) > rbio->bbio->max_errors)
rbio_orig_end_io(rbio, -EIO, 0);
else
__raid_recover_end_io(rbio);
}
/*
* reads everything we need off the disk to reconstruct
* the parity. endio handlers trigger final reconstruction
* when the IO is done.
*
* This is used both for reads from the higher layers and for
* parity construction required to finish a rmw cycle.
*/
static int __raid56_parity_recover(struct btrfs_raid_bio *rbio)
{
int bios_to_read = 0;
struct btrfs_bio *bbio = rbio->bbio;
struct bio_list bio_list;
int ret;
int nr_pages = (rbio->stripe_len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
int pagenr;
int stripe;
struct bio *bio;
bio_list_init(&bio_list);
ret = alloc_rbio_pages(rbio);
if (ret)
goto cleanup;
atomic_set(&rbio->bbio->error, 0);
/*
* read everything that hasn't failed. Thanks to the
* stripe cache, it is possible that some or all of these
* pages are going to be uptodate.
*/
for (stripe = 0; stripe < bbio->num_stripes; stripe++) {
if (rbio->faila == stripe ||
rbio->failb == stripe)
continue;
for (pagenr = 0; pagenr < nr_pages; pagenr++) {
struct page *p;
/*
* the rmw code may have already read this
* page in
*/
p = rbio_stripe_page(rbio, stripe, pagenr);
if (PageUptodate(p))
continue;
ret = rbio_add_io_page(rbio, &bio_list,
rbio_stripe_page(rbio, stripe, pagenr),
stripe, pagenr, rbio->stripe_len);
if (ret < 0)
goto cleanup;
}
}
bios_to_read = bio_list_size(&bio_list);
if (!bios_to_read) {
/*
* we might have no bios to read just because the pages
* were up to date, or we might have no bios to read because
* the devices were gone.
*/
if (atomic_read(&rbio->bbio->error) <= rbio->bbio->max_errors) {
__raid_recover_end_io(rbio);
goto out;
} else {
goto cleanup;
}
}
/*
* the bbio may be freed once we submit the last bio. Make sure
* not to touch it after that
*/
atomic_set(&bbio->stripes_pending, bios_to_read);
while (1) {
bio = bio_list_pop(&bio_list);
if (!bio)
break;
bio->bi_private = rbio;
bio->bi_end_io = raid_recover_end_io;
btrfs_bio_wq_end_io(rbio->fs_info, bio,
BTRFS_WQ_ENDIO_RAID56);
BUG_ON(!test_bit(BIO_UPTODATE, &bio->bi_flags));
submit_bio(READ, bio);
}
out:
return 0;
cleanup:
if (rbio->read_rebuild)
rbio_orig_end_io(rbio, -EIO, 0);
return -EIO;
}
/*
* the main entry point for reads from the higher layers. This
* is really only called when the normal read path had a failure,
* so we assume the bio they send down corresponds to a failed part
* of the drive.
*/
int raid56_parity_recover(struct btrfs_root *root, struct bio *bio,
struct btrfs_bio *bbio, u64 *raid_map,
u64 stripe_len, int mirror_num)
{
struct btrfs_raid_bio *rbio;
int ret;
rbio = alloc_rbio(root, bbio, raid_map, stripe_len);
if (IS_ERR(rbio)) {
return PTR_ERR(rbio);
}
rbio->read_rebuild = 1;
bio_list_add(&rbio->bio_list, bio);
rbio->bio_list_bytes = bio->bi_size;
rbio->faila = find_logical_bio_stripe(rbio, bio);
if (rbio->faila == -1) {
BUG();
kfree(rbio);
return -EIO;
}
/*
* reconstruct from the q stripe if they are
* asking for mirror 3
*/
if (mirror_num == 3)
rbio->failb = bbio->num_stripes - 2;
ret = lock_stripe_add(rbio);
/*
* __raid56_parity_recover will end the bio with
* any errors it hits. We don't want to return
* its error value up the stack because our caller
* will end up calling bio_endio with any nonzero
* return
*/
if (ret == 0)
__raid56_parity_recover(rbio);
/*
* our rbio has been added to the list of
* rbios that will be handled after the
* currently lock owner is done
*/
return 0;
}
static void rmw_work(struct btrfs_work *work)
{
struct btrfs_raid_bio *rbio;
rbio = container_of(work, struct btrfs_raid_bio, work);
raid56_rmw_stripe(rbio);
}
static void read_rebuild_work(struct btrfs_work *work)
{
struct btrfs_raid_bio *rbio;
rbio = container_of(work, struct btrfs_raid_bio, work);
__raid56_parity_recover(rbio);
}