From: Chris Mason <chris.mason@oracle.com>
Date: Sun, 6 Nov 2011 08:07:10 +0000 (-0500)
Subject: Merge git://git.jan-o-sch.net/btrfs-unstable into integration
X-Git-Url: http://git.openwrt.org/?a=commitdiff_plain;h=806468f8bf76a3cb2b626dd282946a6c9c0a50f0;p=openwrt%2Fstaging%2Fblogic.git

Merge git://git.jan-o-sch.net/btrfs-unstable into integration

Conflicts:
	fs/btrfs/Makefile
	fs/btrfs/extent_io.c
	fs/btrfs/extent_io.h
	fs/btrfs/scrub.c

Signed-off-by: Chris Mason <chris.mason@oracle.com>
---

806468f8bf76a3cb2b626dd282946a6c9c0a50f0
diff --cc fs/btrfs/Makefile
index bdd6fb238ce1,89b6ce3634fd..c0ddfd29c5e5
--- a/fs/btrfs/Makefile
+++ b/fs/btrfs/Makefile
@@@ -7,7 -7,7 +7,7 @@@ btrfs-y += super.o ctree.o extent-tree.
  	   extent_map.o sysfs.o struct-funcs.o xattr.o ordered-data.o \
  	   extent_io.o volumes.o async-thread.o ioctl.o locking.o orphan.o \
  	   export.o tree-log.o free-space-cache.o zlib.o lzo.o \
 -	   compression.o delayed-ref.o relocation.o delayed-inode.o backref.o \
 -	   scrub.o
 +	   compression.o delayed-ref.o relocation.o delayed-inode.o scrub.o \
- 	   reada.o
++	   reada.o backref.o
  
  btrfs-$(CONFIG_BTRFS_FS_POSIX_ACL) += acl.o
diff --cc fs/btrfs/disk-io.c
index cedfbfb278eb,dc0343802535..0eb1f0951251
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@@ -618,37 -613,6 +618,37 @@@ out
  	return ret;
  }
  
 +static int btree_io_failed_hook(struct bio *failed_bio,
 +			 struct page *page, u64 start, u64 end,
- 			 struct extent_state *state)
++			 u64 mirror_num, struct extent_state *state)
 +{
 +	struct extent_io_tree *tree;
 +	unsigned long len;
 +	struct extent_buffer *eb;
 +	struct btrfs_root *root = BTRFS_I(page->mapping->host)->root;
 +
 +	tree = &BTRFS_I(page->mapping->host)->io_tree;
 +	if (page->private == EXTENT_PAGE_PRIVATE)
 +		goto out;
 +	if (!page->private)
 +		goto out;
 +
 +	len = page->private >> 2;
 +	WARN_ON(len == 0);
 +
 +	eb = alloc_extent_buffer(tree, start, len, page);
 +	if (eb == NULL)
 +		goto out;
 +
 +	if (test_bit(EXTENT_BUFFER_READAHEAD, &eb->bflags)) {
 +		clear_bit(EXTENT_BUFFER_READAHEAD, &eb->bflags);
 +		btree_readahead_hook(root, eb, eb->start, -EIO);
 +	}
 +
 +out:
 +	return -EIO;	/* we fixed nothing */
 +}
 +
  static void end_workqueue_bio(struct bio *bio, int err)
  {
  	struct end_io_wq *end_io_wq = bio->bi_private;
diff --cc fs/btrfs/extent_io.c
index c12705682c65,624ef10d36cc..1f87c4d0e7a0
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@@ -1915,11 -2093,19 +2281,19 @@@ static void end_bio_extent_readpage(str
  							      state);
  			if (ret)
  				uptodate = 0;
+ 			else
+ 				clean_io_failure(start, page);
  		}
- 		if (!uptodate && tree->ops &&
- 		    tree->ops->readpage_io_failed_hook) {
- 			ret = tree->ops->readpage_io_failed_hook(bio, page,
- 							 start, end, state);
+ 		if (!uptodate) {
+ 			u64 failed_mirror;
+ 			failed_mirror = (u64)bio->bi_bdev;
+ 			if (tree->ops && tree->ops->readpage_io_failed_hook)
+ 				ret = tree->ops->readpage_io_failed_hook(
+ 						bio, page, start, end,
 -						failed_mirror, NULL);
++						failed_mirror, state);
+ 			else
+ 				ret = bio_readpage_error(bio, page, start, end,
+ 							 failed_mirror, NULL);
  			if (ret == 0) {
  				uptodate =
  					test_bit(BIO_UPTODATE, &bio->bi_flags);
diff --cc fs/btrfs/extent_io.h
index 697570eed9e8,a8e20b672922..feb9be0e23bc
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@@ -17,7 -17,7 +17,8 @@@
  #define EXTENT_NODATASUM (1 << 10)
  #define EXTENT_DO_ACCOUNTING (1 << 11)
  #define EXTENT_FIRST_DELALLOC (1 << 12)
 -#define EXTENT_DAMAGED (1 << 13)
 +#define EXTENT_NEED_WAIT (1 << 13)
++#define EXTENT_DAMAGED (1 << 14)
  #define EXTENT_IOBITS (EXTENT_LOCKED | EXTENT_WRITEBACK)
  #define EXTENT_CTLBITS (EXTENT_DO_ACCOUNTING | EXTENT_FIRST_DELALLOC)
  
diff --cc fs/btrfs/ioctl.c
index 8f6e14279409,7f57efa76d11..cc9893990341
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@@ -2890,6 -2856,144 +2891,144 @@@ static long btrfs_ioctl_scrub_progress(
  	return ret;
  }
  
+ static long btrfs_ioctl_ino_to_path(struct btrfs_root *root, void __user *arg)
+ {
+ 	int ret = 0;
+ 	int i;
+ 	unsigned long rel_ptr;
+ 	int size;
 -	struct btrfs_ioctl_ino_path_args *ipa;
++	struct btrfs_ioctl_ino_path_args *ipa = NULL;
+ 	struct inode_fs_paths *ipath = NULL;
+ 	struct btrfs_path *path;
+ 
+ 	if (!capable(CAP_SYS_ADMIN))
+ 		return -EPERM;
+ 
+ 	path = btrfs_alloc_path();
+ 	if (!path) {
+ 		ret = -ENOMEM;
+ 		goto out;
+ 	}
+ 
+ 	ipa = memdup_user(arg, sizeof(*ipa));
+ 	if (IS_ERR(ipa)) {
+ 		ret = PTR_ERR(ipa);
+ 		ipa = NULL;
+ 		goto out;
+ 	}
+ 
+ 	size = min_t(u32, ipa->size, 4096);
+ 	ipath = init_ipath(size, root, path);
+ 	if (IS_ERR(ipath)) {
+ 		ret = PTR_ERR(ipath);
+ 		ipath = NULL;
+ 		goto out;
+ 	}
+ 
+ 	ret = paths_from_inode(ipa->inum, ipath);
+ 	if (ret < 0)
+ 		goto out;
+ 
+ 	for (i = 0; i < ipath->fspath->elem_cnt; ++i) {
+ 		rel_ptr = ipath->fspath->str[i] - (char *)ipath->fspath->str;
+ 		ipath->fspath->str[i] = (void *)rel_ptr;
+ 	}
+ 
+ 	ret = copy_to_user(ipa->fspath, ipath->fspath, size);
+ 	if (ret) {
+ 		ret = -EFAULT;
+ 		goto out;
+ 	}
+ 
+ out:
+ 	btrfs_free_path(path);
+ 	free_ipath(ipath);
+ 	kfree(ipa);
+ 
+ 	return ret;
+ }
+ 
+ static int build_ino_list(u64 inum, u64 offset, u64 root, void *ctx)
+ {
+ 	struct btrfs_data_container *inodes = ctx;
+ 	const size_t c = 3 * sizeof(u64);
+ 
+ 	if (inodes->bytes_left >= c) {
+ 		inodes->bytes_left -= c;
+ 		inodes->val[inodes->elem_cnt] = inum;
+ 		inodes->val[inodes->elem_cnt + 1] = offset;
+ 		inodes->val[inodes->elem_cnt + 2] = root;
+ 		inodes->elem_cnt += 3;
+ 	} else {
+ 		inodes->bytes_missing += c - inodes->bytes_left;
+ 		inodes->bytes_left = 0;
+ 		inodes->elem_missed += 3;
+ 	}
+ 
+ 	return 0;
+ }
+ 
+ static long btrfs_ioctl_logical_to_ino(struct btrfs_root *root,
+ 					void __user *arg)
+ {
+ 	int ret = 0;
+ 	int size;
+ 	u64 extent_offset;
+ 	struct btrfs_ioctl_logical_ino_args *loi;
+ 	struct btrfs_data_container *inodes = NULL;
+ 	struct btrfs_path *path = NULL;
+ 	struct btrfs_key key;
+ 
+ 	if (!capable(CAP_SYS_ADMIN))
+ 		return -EPERM;
+ 
+ 	loi = memdup_user(arg, sizeof(*loi));
+ 	if (IS_ERR(loi)) {
+ 		ret = PTR_ERR(loi);
+ 		loi = NULL;
+ 		goto out;
+ 	}
+ 
+ 	path = btrfs_alloc_path();
+ 	if (!path) {
+ 		ret = -ENOMEM;
+ 		goto out;
+ 	}
+ 
+ 	size = min_t(u32, loi->size, 4096);
+ 	inodes = init_data_container(size);
+ 	if (IS_ERR(inodes)) {
+ 		ret = PTR_ERR(inodes);
+ 		inodes = NULL;
+ 		goto out;
+ 	}
+ 
+ 	ret = extent_from_logical(root->fs_info, loi->logical, path, &key);
+ 
+ 	if (ret & BTRFS_EXTENT_FLAG_TREE_BLOCK)
+ 		ret = -ENOENT;
+ 	if (ret < 0)
+ 		goto out;
+ 
+ 	extent_offset = loi->logical - key.objectid;
+ 	ret = iterate_extent_inodes(root->fs_info, path, key.objectid,
+ 					extent_offset, build_ino_list, inodes);
+ 
+ 	if (ret < 0)
+ 		goto out;
+ 
+ 	ret = copy_to_user(loi->inodes, inodes, size);
+ 	if (ret)
+ 		ret = -EFAULT;
+ 
+ out:
+ 	btrfs_free_path(path);
+ 	kfree(inodes);
+ 	kfree(loi);
+ 
+ 	return ret;
+ }
+ 
  long btrfs_ioctl(struct file *file, unsigned int
  		cmd, unsigned long arg)
  {
diff --cc fs/btrfs/reada.c
index 2b701d082227,000000000000..cd857119ba8a
mode 100644,000000..100644
--- a/fs/btrfs/reada.c
+++ b/fs/btrfs/reada.c
@@@ -1,949 -1,0 +1,949 @@@
 +/*
 + * Copyright (C) 2011 STRATO.  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/pagemap.h>
 +#include <linux/writeback.h>
 +#include <linux/blkdev.h>
 +#include <linux/rbtree.h>
 +#include <linux/slab.h>
 +#include <linux/workqueue.h>
 +#include "ctree.h"
 +#include "volumes.h"
 +#include "disk-io.h"
 +#include "transaction.h"
 +
 +#undef DEBUG
 +
 +/*
 + * This is the implementation for the generic read ahead framework.
 + *
 + * To trigger a readahead, btrfs_reada_add must be called. It will start
 + * a read ahead for the given range [start, end) on tree root. The returned
 + * handle can either be used to wait on the readahead to finish
 + * (btrfs_reada_wait), or to send it to the background (btrfs_reada_detach).
 + *
 + * The read ahead works as follows:
 + * On btrfs_reada_add, the root of the tree is inserted into a radix_tree.
 + * reada_start_machine will then search for extents to prefetch and trigger
 + * some reads. When a read finishes for a node, all contained node/leaf
 + * pointers that lie in the given range will also be enqueued. The reads will
 + * be triggered in sequential order, thus giving a big win over a naive
 + * enumeration. It will also make use of multi-device layouts. Each disk
 + * will have its on read pointer and all disks will by utilized in parallel.
 + * Also will no two disks read both sides of a mirror simultaneously, as this
 + * would waste seeking capacity. Instead both disks will read different parts
 + * of the filesystem.
 + * Any number of readaheads can be started in parallel. The read order will be
 + * determined globally, i.e. 2 parallel readaheads will normally finish faster
 + * than the 2 started one after another.
 + */
 +
 +#define MAX_MIRRORS 2
 +#define MAX_IN_FLIGHT 6
 +
 +struct reada_extctl {
 +	struct list_head	list;
 +	struct reada_control	*rc;
 +	u64			generation;
 +};
 +
 +struct reada_extent {
 +	u64			logical;
 +	struct btrfs_key	top;
 +	u32			blocksize;
 +	int			err;
 +	struct list_head	extctl;
 +	struct kref		refcnt;
 +	spinlock_t		lock;
 +	struct reada_zone	*zones[MAX_MIRRORS];
 +	int			nzones;
 +	struct btrfs_device	*scheduled_for;
 +};
 +
 +struct reada_zone {
 +	u64			start;
 +	u64			end;
 +	u64			elems;
 +	struct list_head	list;
 +	spinlock_t		lock;
 +	int			locked;
 +	struct btrfs_device	*device;
 +	struct btrfs_device	*devs[MAX_MIRRORS]; /* full list, incl self */
 +	int			ndevs;
 +	struct kref		refcnt;
 +};
 +
 +struct reada_machine_work {
 +	struct btrfs_work	work;
 +	struct btrfs_fs_info	*fs_info;
 +};
 +
 +static void reada_extent_put(struct btrfs_fs_info *, struct reada_extent *);
 +static void reada_control_release(struct kref *kref);
 +static void reada_zone_release(struct kref *kref);
 +static void reada_start_machine(struct btrfs_fs_info *fs_info);
 +static void __reada_start_machine(struct btrfs_fs_info *fs_info);
 +
 +static int reada_add_block(struct reada_control *rc, u64 logical,
 +			   struct btrfs_key *top, int level, u64 generation);
 +
 +/* recurses */
 +/* in case of err, eb might be NULL */
 +static int __readahead_hook(struct btrfs_root *root, struct extent_buffer *eb,
 +			    u64 start, int err)
 +{
 +	int level = 0;
 +	int nritems;
 +	int i;
 +	u64 bytenr;
 +	u64 generation;
 +	struct reada_extent *re;
 +	struct btrfs_fs_info *fs_info = root->fs_info;
 +	struct list_head list;
 +	unsigned long index = start >> PAGE_CACHE_SHIFT;
 +	struct btrfs_device *for_dev;
 +
 +	if (eb)
 +		level = btrfs_header_level(eb);
 +
 +	/* find extent */
 +	spin_lock(&fs_info->reada_lock);
 +	re = radix_tree_lookup(&fs_info->reada_tree, index);
 +	if (re)
 +		kref_get(&re->refcnt);
 +	spin_unlock(&fs_info->reada_lock);
 +
 +	if (!re)
 +		return -1;
 +
 +	spin_lock(&re->lock);
 +	/*
 +	 * just take the full list from the extent. afterwards we
 +	 * don't need the lock anymore
 +	 */
 +	list_replace_init(&re->extctl, &list);
 +	for_dev = re->scheduled_for;
 +	re->scheduled_for = NULL;
 +	spin_unlock(&re->lock);
 +
 +	if (err == 0) {
 +		nritems = level ? btrfs_header_nritems(eb) : 0;
 +		generation = btrfs_header_generation(eb);
 +		/*
 +		 * FIXME: currently we just set nritems to 0 if this is a leaf,
 +		 * effectively ignoring the content. In a next step we could
 +		 * trigger more readahead depending from the content, e.g.
 +		 * fetch the checksums for the extents in the leaf.
 +		 */
 +	} else {
 +		/*
 +		 * this is the error case, the extent buffer has not been
 +		 * read correctly. We won't access anything from it and
 +		 * just cleanup our data structures. Effectively this will
 +		 * cut the branch below this node from read ahead.
 +		 */
 +		nritems = 0;
 +		generation = 0;
 +	}
 +
 +	for (i = 0; i < nritems; i++) {
 +		struct reada_extctl *rec;
 +		u64 n_gen;
 +		struct btrfs_key key;
 +		struct btrfs_key next_key;
 +
 +		btrfs_node_key_to_cpu(eb, &key, i);
 +		if (i + 1 < nritems)
 +			btrfs_node_key_to_cpu(eb, &next_key, i + 1);
 +		else
 +			next_key = re->top;
 +		bytenr = btrfs_node_blockptr(eb, i);
 +		n_gen = btrfs_node_ptr_generation(eb, i);
 +
 +		list_for_each_entry(rec, &list, list) {
 +			struct reada_control *rc = rec->rc;
 +
 +			/*
 +			 * if the generation doesn't match, just ignore this
 +			 * extctl. This will probably cut off a branch from
 +			 * prefetch. Alternatively one could start a new (sub-)
 +			 * prefetch for this branch, starting again from root.
 +			 * FIXME: move the generation check out of this loop
 +			 */
 +#ifdef DEBUG
 +			if (rec->generation != generation) {
 +				printk(KERN_DEBUG "generation mismatch for "
 +						"(%llu,%d,%llu) %llu != %llu\n",
 +				       key.objectid, key.type, key.offset,
 +				       rec->generation, generation);
 +			}
 +#endif
 +			if (rec->generation == generation &&
 +			    btrfs_comp_cpu_keys(&key, &rc->key_end) < 0 &&
 +			    btrfs_comp_cpu_keys(&next_key, &rc->key_start) > 0)
 +				reada_add_block(rc, bytenr, &next_key,
 +						level - 1, n_gen);
 +		}
 +	}
 +	/*
 +	 * free extctl records
 +	 */
 +	while (!list_empty(&list)) {
 +		struct reada_control *rc;
 +		struct reada_extctl *rec;
 +
 +		rec = list_first_entry(&list, struct reada_extctl, list);
 +		list_del(&rec->list);
 +		rc = rec->rc;
 +		kfree(rec);
 +
 +		kref_get(&rc->refcnt);
 +		if (atomic_dec_and_test(&rc->elems)) {
 +			kref_put(&rc->refcnt, reada_control_release);
 +			wake_up(&rc->wait);
 +		}
 +		kref_put(&rc->refcnt, reada_control_release);
 +
 +		reada_extent_put(fs_info, re);	/* one ref for each entry */
 +	}
 +	reada_extent_put(fs_info, re);	/* our ref */
 +	if (for_dev)
 +		atomic_dec(&for_dev->reada_in_flight);
 +
 +	return 0;
 +}
 +
 +/*
 + * start is passed separately in case eb in NULL, which may be the case with
 + * failed I/O
 + */
 +int btree_readahead_hook(struct btrfs_root *root, struct extent_buffer *eb,
 +			 u64 start, int err)
 +{
 +	int ret;
 +
 +	ret = __readahead_hook(root, eb, start, err);
 +
 +	reada_start_machine(root->fs_info);
 +
 +	return ret;
 +}
 +
 +static struct reada_zone *reada_find_zone(struct btrfs_fs_info *fs_info,
 +					  struct btrfs_device *dev, u64 logical,
- 					  struct btrfs_multi_bio *multi)
++					  struct btrfs_bio *multi)
 +{
 +	int ret;
 +	int looped = 0;
 +	struct reada_zone *zone;
 +	struct btrfs_block_group_cache *cache = NULL;
 +	u64 start;
 +	u64 end;
 +	int i;
 +
 +again:
 +	zone = NULL;
 +	spin_lock(&fs_info->reada_lock);
 +	ret = radix_tree_gang_lookup(&dev->reada_zones, (void **)&zone,
 +				     logical >> PAGE_CACHE_SHIFT, 1);
 +	if (ret == 1)
 +		kref_get(&zone->refcnt);
 +	spin_unlock(&fs_info->reada_lock);
 +
 +	if (ret == 1) {
 +		if (logical >= zone->start && logical < zone->end)
 +			return zone;
 +		spin_lock(&fs_info->reada_lock);
 +		kref_put(&zone->refcnt, reada_zone_release);
 +		spin_unlock(&fs_info->reada_lock);
 +	}
 +
 +	if (looped)
 +		return NULL;
 +
 +	cache = btrfs_lookup_block_group(fs_info, logical);
 +	if (!cache)
 +		return NULL;
 +
 +	start = cache->key.objectid;
 +	end = start + cache->key.offset - 1;
 +	btrfs_put_block_group(cache);
 +
 +	zone = kzalloc(sizeof(*zone), GFP_NOFS);
 +	if (!zone)
 +		return NULL;
 +
 +	zone->start = start;
 +	zone->end = end;
 +	INIT_LIST_HEAD(&zone->list);
 +	spin_lock_init(&zone->lock);
 +	zone->locked = 0;
 +	kref_init(&zone->refcnt);
 +	zone->elems = 0;
 +	zone->device = dev; /* our device always sits at index 0 */
 +	for (i = 0; i < multi->num_stripes; ++i) {
 +		/* bounds have already been checked */
 +		zone->devs[i] = multi->stripes[i].dev;
 +	}
 +	zone->ndevs = multi->num_stripes;
 +
 +	spin_lock(&fs_info->reada_lock);
 +	ret = radix_tree_insert(&dev->reada_zones,
 +				(unsigned long)zone->end >> PAGE_CACHE_SHIFT,
 +				zone);
 +	spin_unlock(&fs_info->reada_lock);
 +
 +	if (ret) {
 +		kfree(zone);
 +		looped = 1;
 +		goto again;
 +	}
 +
 +	return zone;
 +}
 +
 +static struct reada_extent *reada_find_extent(struct btrfs_root *root,
 +					      u64 logical,
 +					      struct btrfs_key *top, int level)
 +{
 +	int ret;
 +	int looped = 0;
 +	struct reada_extent *re = NULL;
 +	struct btrfs_fs_info *fs_info = root->fs_info;
 +	struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
- 	struct btrfs_multi_bio *multi = NULL;
++	struct btrfs_bio *multi = NULL;
 +	struct btrfs_device *dev;
 +	u32 blocksize;
 +	u64 length;
 +	int nzones = 0;
 +	int i;
 +	unsigned long index = logical >> PAGE_CACHE_SHIFT;
 +
 +again:
 +	spin_lock(&fs_info->reada_lock);
 +	re = radix_tree_lookup(&fs_info->reada_tree, index);
 +	if (re)
 +		kref_get(&re->refcnt);
 +	spin_unlock(&fs_info->reada_lock);
 +
 +	if (re || looped)
 +		return re;
 +
 +	re = kzalloc(sizeof(*re), GFP_NOFS);
 +	if (!re)
 +		return NULL;
 +
 +	blocksize = btrfs_level_size(root, level);
 +	re->logical = logical;
 +	re->blocksize = blocksize;
 +	re->top = *top;
 +	INIT_LIST_HEAD(&re->extctl);
 +	spin_lock_init(&re->lock);
 +	kref_init(&re->refcnt);
 +
 +	/*
 +	 * map block
 +	 */
 +	length = blocksize;
 +	ret = btrfs_map_block(map_tree, REQ_WRITE, logical, &length, &multi, 0);
 +	if (ret || !multi || length < blocksize)
 +		goto error;
 +
 +	if (multi->num_stripes > MAX_MIRRORS) {
 +		printk(KERN_ERR "btrfs readahead: more than %d copies not "
 +				"supported", MAX_MIRRORS);
 +		goto error;
 +	}
 +
 +	for (nzones = 0; nzones < multi->num_stripes; ++nzones) {
 +		struct reada_zone *zone;
 +
 +		dev = multi->stripes[nzones].dev;
 +		zone = reada_find_zone(fs_info, dev, logical, multi);
 +		if (!zone)
 +			break;
 +
 +		re->zones[nzones] = zone;
 +		spin_lock(&zone->lock);
 +		if (!zone->elems)
 +			kref_get(&zone->refcnt);
 +		++zone->elems;
 +		spin_unlock(&zone->lock);
 +		spin_lock(&fs_info->reada_lock);
 +		kref_put(&zone->refcnt, reada_zone_release);
 +		spin_unlock(&fs_info->reada_lock);
 +	}
 +	re->nzones = nzones;
 +	if (nzones == 0) {
 +		/* not a single zone found, error and out */
 +		goto error;
 +	}
 +
 +	/* insert extent in reada_tree + all per-device trees, all or nothing */
 +	spin_lock(&fs_info->reada_lock);
 +	ret = radix_tree_insert(&fs_info->reada_tree, index, re);
 +	if (ret) {
 +		spin_unlock(&fs_info->reada_lock);
 +		if (ret != -ENOMEM) {
 +			/* someone inserted the extent in the meantime */
 +			looped = 1;
 +		}
 +		goto error;
 +	}
 +	for (i = 0; i < nzones; ++i) {
 +		dev = multi->stripes[i].dev;
 +		ret = radix_tree_insert(&dev->reada_extents, index, re);
 +		if (ret) {
 +			while (--i >= 0) {
 +				dev = multi->stripes[i].dev;
 +				BUG_ON(dev == NULL);
 +				radix_tree_delete(&dev->reada_extents, index);
 +			}
 +			BUG_ON(fs_info == NULL);
 +			radix_tree_delete(&fs_info->reada_tree, index);
 +			spin_unlock(&fs_info->reada_lock);
 +			goto error;
 +		}
 +	}
 +	spin_unlock(&fs_info->reada_lock);
 +
 +	return re;
 +
 +error:
 +	while (nzones) {
 +		struct reada_zone *zone;
 +
 +		--nzones;
 +		zone = re->zones[nzones];
 +		kref_get(&zone->refcnt);
 +		spin_lock(&zone->lock);
 +		--zone->elems;
 +		if (zone->elems == 0) {
 +			/*
 +			 * no fs_info->reada_lock needed, as this can't be
 +			 * the last ref
 +			 */
 +			kref_put(&zone->refcnt, reada_zone_release);
 +		}
 +		spin_unlock(&zone->lock);
 +
 +		spin_lock(&fs_info->reada_lock);
 +		kref_put(&zone->refcnt, reada_zone_release);
 +		spin_unlock(&fs_info->reada_lock);
 +	}
 +	kfree(re);
 +	if (looped)
 +		goto again;
 +	return NULL;
 +}
 +
 +static void reada_kref_dummy(struct kref *kr)
 +{
 +}
 +
 +static void reada_extent_put(struct btrfs_fs_info *fs_info,
 +			     struct reada_extent *re)
 +{
 +	int i;
 +	unsigned long index = re->logical >> PAGE_CACHE_SHIFT;
 +
 +	spin_lock(&fs_info->reada_lock);
 +	if (!kref_put(&re->refcnt, reada_kref_dummy)) {
 +		spin_unlock(&fs_info->reada_lock);
 +		return;
 +	}
 +
 +	radix_tree_delete(&fs_info->reada_tree, index);
 +	for (i = 0; i < re->nzones; ++i) {
 +		struct reada_zone *zone = re->zones[i];
 +
 +		radix_tree_delete(&zone->device->reada_extents, index);
 +	}
 +
 +	spin_unlock(&fs_info->reada_lock);
 +
 +	for (i = 0; i < re->nzones; ++i) {
 +		struct reada_zone *zone = re->zones[i];
 +
 +		kref_get(&zone->refcnt);
 +		spin_lock(&zone->lock);
 +		--zone->elems;
 +		if (zone->elems == 0) {
 +			/* no fs_info->reada_lock needed, as this can't be
 +			 * the last ref */
 +			kref_put(&zone->refcnt, reada_zone_release);
 +		}
 +		spin_unlock(&zone->lock);
 +
 +		spin_lock(&fs_info->reada_lock);
 +		kref_put(&zone->refcnt, reada_zone_release);
 +		spin_unlock(&fs_info->reada_lock);
 +	}
 +	if (re->scheduled_for)
 +		atomic_dec(&re->scheduled_for->reada_in_flight);
 +
 +	kfree(re);
 +}
 +
 +static void reada_zone_release(struct kref *kref)
 +{
 +	struct reada_zone *zone = container_of(kref, struct reada_zone, refcnt);
 +
 +	radix_tree_delete(&zone->device->reada_zones,
 +			  zone->end >> PAGE_CACHE_SHIFT);
 +
 +	kfree(zone);
 +}
 +
 +static void reada_control_release(struct kref *kref)
 +{
 +	struct reada_control *rc = container_of(kref, struct reada_control,
 +						refcnt);
 +
 +	kfree(rc);
 +}
 +
 +static int reada_add_block(struct reada_control *rc, u64 logical,
 +			   struct btrfs_key *top, int level, u64 generation)
 +{
 +	struct btrfs_root *root = rc->root;
 +	struct reada_extent *re;
 +	struct reada_extctl *rec;
 +
 +	re = reada_find_extent(root, logical, top, level); /* takes one ref */
 +	if (!re)
 +		return -1;
 +
 +	rec = kzalloc(sizeof(*rec), GFP_NOFS);
 +	if (!rec) {
 +		reada_extent_put(root->fs_info, re);
 +		return -1;
 +	}
 +
 +	rec->rc = rc;
 +	rec->generation = generation;
 +	atomic_inc(&rc->elems);
 +
 +	spin_lock(&re->lock);
 +	list_add_tail(&rec->list, &re->extctl);
 +	spin_unlock(&re->lock);
 +
 +	/* leave the ref on the extent */
 +
 +	return 0;
 +}
 +
 +/*
 + * called with fs_info->reada_lock held
 + */
 +static void reada_peer_zones_set_lock(struct reada_zone *zone, int lock)
 +{
 +	int i;
 +	unsigned long index = zone->end >> PAGE_CACHE_SHIFT;
 +
 +	for (i = 0; i < zone->ndevs; ++i) {
 +		struct reada_zone *peer;
 +		peer = radix_tree_lookup(&zone->devs[i]->reada_zones, index);
 +		if (peer && peer->device != zone->device)
 +			peer->locked = lock;
 +	}
 +}
 +
 +/*
 + * called with fs_info->reada_lock held
 + */
 +static int reada_pick_zone(struct btrfs_device *dev)
 +{
 +	struct reada_zone *top_zone = NULL;
 +	struct reada_zone *top_locked_zone = NULL;
 +	u64 top_elems = 0;
 +	u64 top_locked_elems = 0;
 +	unsigned long index = 0;
 +	int ret;
 +
 +	if (dev->reada_curr_zone) {
 +		reada_peer_zones_set_lock(dev->reada_curr_zone, 0);
 +		kref_put(&dev->reada_curr_zone->refcnt, reada_zone_release);
 +		dev->reada_curr_zone = NULL;
 +	}
 +	/* pick the zone with the most elements */
 +	while (1) {
 +		struct reada_zone *zone;
 +
 +		ret = radix_tree_gang_lookup(&dev->reada_zones,
 +					     (void **)&zone, index, 1);
 +		if (ret == 0)
 +			break;
 +		index = (zone->end >> PAGE_CACHE_SHIFT) + 1;
 +		if (zone->locked) {
 +			if (zone->elems > top_locked_elems) {
 +				top_locked_elems = zone->elems;
 +				top_locked_zone = zone;
 +			}
 +		} else {
 +			if (zone->elems > top_elems) {
 +				top_elems = zone->elems;
 +				top_zone = zone;
 +			}
 +		}
 +	}
 +	if (top_zone)
 +		dev->reada_curr_zone = top_zone;
 +	else if (top_locked_zone)
 +		dev->reada_curr_zone = top_locked_zone;
 +	else
 +		return 0;
 +
 +	dev->reada_next = dev->reada_curr_zone->start;
 +	kref_get(&dev->reada_curr_zone->refcnt);
 +	reada_peer_zones_set_lock(dev->reada_curr_zone, 1);
 +
 +	return 1;
 +}
 +
 +static int reada_start_machine_dev(struct btrfs_fs_info *fs_info,
 +				   struct btrfs_device *dev)
 +{
 +	struct reada_extent *re = NULL;
 +	int mirror_num = 0;
 +	struct extent_buffer *eb = NULL;
 +	u64 logical;
 +	u32 blocksize;
 +	int ret;
 +	int i;
 +	int need_kick = 0;
 +
 +	spin_lock(&fs_info->reada_lock);
 +	if (dev->reada_curr_zone == NULL) {
 +		ret = reada_pick_zone(dev);
 +		if (!ret) {
 +			spin_unlock(&fs_info->reada_lock);
 +			return 0;
 +		}
 +	}
 +	/*
 +	 * FIXME currently we issue the reads one extent at a time. If we have
 +	 * a contiguous block of extents, we could also coagulate them or use
 +	 * plugging to speed things up
 +	 */
 +	ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re,
 +				     dev->reada_next >> PAGE_CACHE_SHIFT, 1);
 +	if (ret == 0 || re->logical >= dev->reada_curr_zone->end) {
 +		ret = reada_pick_zone(dev);
 +		if (!ret) {
 +			spin_unlock(&fs_info->reada_lock);
 +			return 0;
 +		}
 +		re = NULL;
 +		ret = radix_tree_gang_lookup(&dev->reada_extents, (void **)&re,
 +					dev->reada_next >> PAGE_CACHE_SHIFT, 1);
 +	}
 +	if (ret == 0) {
 +		spin_unlock(&fs_info->reada_lock);
 +		return 0;
 +	}
 +	dev->reada_next = re->logical + re->blocksize;
 +	kref_get(&re->refcnt);
 +
 +	spin_unlock(&fs_info->reada_lock);
 +
 +	/*
 +	 * find mirror num
 +	 */
 +	for (i = 0; i < re->nzones; ++i) {
 +		if (re->zones[i]->device == dev) {
 +			mirror_num = i + 1;
 +			break;
 +		}
 +	}
 +	logical = re->logical;
 +	blocksize = re->blocksize;
 +
 +	spin_lock(&re->lock);
 +	if (re->scheduled_for == NULL) {
 +		re->scheduled_for = dev;
 +		need_kick = 1;
 +	}
 +	spin_unlock(&re->lock);
 +
 +	reada_extent_put(fs_info, re);
 +
 +	if (!need_kick)
 +		return 0;
 +
 +	atomic_inc(&dev->reada_in_flight);
 +	ret = reada_tree_block_flagged(fs_info->extent_root, logical, blocksize,
 +			 mirror_num, &eb);
 +	if (ret)
 +		__readahead_hook(fs_info->extent_root, NULL, logical, ret);
 +	else if (eb)
 +		__readahead_hook(fs_info->extent_root, eb, eb->start, ret);
 +
 +	if (eb)
 +		free_extent_buffer(eb);
 +
 +	return 1;
 +
 +}
 +
 +static void reada_start_machine_worker(struct btrfs_work *work)
 +{
 +	struct reada_machine_work *rmw;
 +	struct btrfs_fs_info *fs_info;
 +
 +	rmw = container_of(work, struct reada_machine_work, work);
 +	fs_info = rmw->fs_info;
 +
 +	kfree(rmw);
 +
 +	__reada_start_machine(fs_info);
 +}
 +
 +static void __reada_start_machine(struct btrfs_fs_info *fs_info)
 +{
 +	struct btrfs_device *device;
 +	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
 +	u64 enqueued;
 +	u64 total = 0;
 +	int i;
 +
 +	do {
 +		enqueued = 0;
 +		list_for_each_entry(device, &fs_devices->devices, dev_list) {
 +			if (atomic_read(&device->reada_in_flight) <
 +			    MAX_IN_FLIGHT)
 +				enqueued += reada_start_machine_dev(fs_info,
 +								    device);
 +		}
 +		total += enqueued;
 +	} while (enqueued && total < 10000);
 +
 +	if (enqueued == 0)
 +		return;
 +
 +	/*
 +	 * If everything is already in the cache, this is effectively single
 +	 * threaded. To a) not hold the caller for too long and b) to utilize
 +	 * more cores, we broke the loop above after 10000 iterations and now
 +	 * enqueue to workers to finish it. This will distribute the load to
 +	 * the cores.
 +	 */
 +	for (i = 0; i < 2; ++i)
 +		reada_start_machine(fs_info);
 +}
 +
 +static void reada_start_machine(struct btrfs_fs_info *fs_info)
 +{
 +	struct reada_machine_work *rmw;
 +
 +	rmw = kzalloc(sizeof(*rmw), GFP_NOFS);
 +	if (!rmw) {
 +		/* FIXME we cannot handle this properly right now */
 +		BUG();
 +	}
 +	rmw->work.func = reada_start_machine_worker;
 +	rmw->fs_info = fs_info;
 +
 +	btrfs_queue_worker(&fs_info->readahead_workers, &rmw->work);
 +}
 +
 +#ifdef DEBUG
 +static void dump_devs(struct btrfs_fs_info *fs_info, int all)
 +{
 +	struct btrfs_device *device;
 +	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
 +	unsigned long index;
 +	int ret;
 +	int i;
 +	int j;
 +	int cnt;
 +
 +	spin_lock(&fs_info->reada_lock);
 +	list_for_each_entry(device, &fs_devices->devices, dev_list) {
 +		printk(KERN_DEBUG "dev %lld has %d in flight\n", device->devid,
 +			atomic_read(&device->reada_in_flight));
 +		index = 0;
 +		while (1) {
 +			struct reada_zone *zone;
 +			ret = radix_tree_gang_lookup(&device->reada_zones,
 +						     (void **)&zone, index, 1);
 +			if (ret == 0)
 +				break;
 +			printk(KERN_DEBUG "  zone %llu-%llu elems %llu locked "
 +				"%d devs", zone->start, zone->end, zone->elems,
 +				zone->locked);
 +			for (j = 0; j < zone->ndevs; ++j) {
 +				printk(KERN_CONT " %lld",
 +					zone->devs[j]->devid);
 +			}
 +			if (device->reada_curr_zone == zone)
 +				printk(KERN_CONT " curr off %llu",
 +					device->reada_next - zone->start);
 +			printk(KERN_CONT "\n");
 +			index = (zone->end >> PAGE_CACHE_SHIFT) + 1;
 +		}
 +		cnt = 0;
 +		index = 0;
 +		while (all) {
 +			struct reada_extent *re = NULL;
 +
 +			ret = radix_tree_gang_lookup(&device->reada_extents,
 +						     (void **)&re, index, 1);
 +			if (ret == 0)
 +				break;
 +			printk(KERN_DEBUG
 +				"  re: logical %llu size %u empty %d for %lld",
 +				re->logical, re->blocksize,
 +				list_empty(&re->extctl), re->scheduled_for ?
 +				re->scheduled_for->devid : -1);
 +
 +			for (i = 0; i < re->nzones; ++i) {
 +				printk(KERN_CONT " zone %llu-%llu devs",
 +					re->zones[i]->start,
 +					re->zones[i]->end);
 +				for (j = 0; j < re->zones[i]->ndevs; ++j) {
 +					printk(KERN_CONT " %lld",
 +						re->zones[i]->devs[j]->devid);
 +				}
 +			}
 +			printk(KERN_CONT "\n");
 +			index = (re->logical >> PAGE_CACHE_SHIFT) + 1;
 +			if (++cnt > 15)
 +				break;
 +		}
 +	}
 +
 +	index = 0;
 +	cnt = 0;
 +	while (all) {
 +		struct reada_extent *re = NULL;
 +
 +		ret = radix_tree_gang_lookup(&fs_info->reada_tree, (void **)&re,
 +					     index, 1);
 +		if (ret == 0)
 +			break;
 +		if (!re->scheduled_for) {
 +			index = (re->logical >> PAGE_CACHE_SHIFT) + 1;
 +			continue;
 +		}
 +		printk(KERN_DEBUG
 +			"re: logical %llu size %u list empty %d for %lld",
 +			re->logical, re->blocksize, list_empty(&re->extctl),
 +			re->scheduled_for ? re->scheduled_for->devid : -1);
 +		for (i = 0; i < re->nzones; ++i) {
 +			printk(KERN_CONT " zone %llu-%llu devs",
 +				re->zones[i]->start,
 +				re->zones[i]->end);
 +			for (i = 0; i < re->nzones; ++i) {
 +				printk(KERN_CONT " zone %llu-%llu devs",
 +					re->zones[i]->start,
 +					re->zones[i]->end);
 +				for (j = 0; j < re->zones[i]->ndevs; ++j) {
 +					printk(KERN_CONT " %lld",
 +						re->zones[i]->devs[j]->devid);
 +				}
 +			}
 +		}
 +		printk(KERN_CONT "\n");
 +		index = (re->logical >> PAGE_CACHE_SHIFT) + 1;
 +	}
 +	spin_unlock(&fs_info->reada_lock);
 +}
 +#endif
 +
 +/*
 + * interface
 + */
 +struct reada_control *btrfs_reada_add(struct btrfs_root *root,
 +			struct btrfs_key *key_start, struct btrfs_key *key_end)
 +{
 +	struct reada_control *rc;
 +	u64 start;
 +	u64 generation;
 +	int level;
 +	struct extent_buffer *node;
 +	static struct btrfs_key max_key = {
 +		.objectid = (u64)-1,
 +		.type = (u8)-1,
 +		.offset = (u64)-1
 +	};
 +
 +	rc = kzalloc(sizeof(*rc), GFP_NOFS);
 +	if (!rc)
 +		return ERR_PTR(-ENOMEM);
 +
 +	rc->root = root;
 +	rc->key_start = *key_start;
 +	rc->key_end = *key_end;
 +	atomic_set(&rc->elems, 0);
 +	init_waitqueue_head(&rc->wait);
 +	kref_init(&rc->refcnt);
 +	kref_get(&rc->refcnt); /* one ref for having elements */
 +
 +	node = btrfs_root_node(root);
 +	start = node->start;
 +	level = btrfs_header_level(node);
 +	generation = btrfs_header_generation(node);
 +	free_extent_buffer(node);
 +
 +	reada_add_block(rc, start, &max_key, level, generation);
 +
 +	reada_start_machine(root->fs_info);
 +
 +	return rc;
 +}
 +
 +#ifdef DEBUG
 +int btrfs_reada_wait(void *handle)
 +{
 +	struct reada_control *rc = handle;
 +
 +	while (atomic_read(&rc->elems)) {
 +		wait_event_timeout(rc->wait, atomic_read(&rc->elems) == 0,
 +				   5 * HZ);
 +		dump_devs(rc->root->fs_info, rc->elems < 10 ? 1 : 0);
 +	}
 +
 +	dump_devs(rc->root->fs_info, rc->elems < 10 ? 1 : 0);
 +
 +	kref_put(&rc->refcnt, reada_control_release);
 +
 +	return 0;
 +}
 +#else
 +int btrfs_reada_wait(void *handle)
 +{
 +	struct reada_control *rc = handle;
 +
 +	while (atomic_read(&rc->elems)) {
 +		wait_event(rc->wait, atomic_read(&rc->elems) == 0);
 +	}
 +
 +	kref_put(&rc->refcnt, reada_control_release);
 +
 +	return 0;
 +}
 +#endif
 +
 +void btrfs_reada_detach(void *handle)
 +{
 +	struct reada_control *rc = handle;
 +
 +	kref_put(&rc->refcnt, reada_control_release);
 +}
diff --cc fs/btrfs/scrub.c
index 5bc4ec827b3d,eba42e5fd5fd..94cd3a19e9c8
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@@ -178,8 -207,9 +204,9 @@@ struct scrub_dev *scrub_setup_dev(struc
  	sdev->first_free = 0;
  	sdev->curr = -1;
  	atomic_set(&sdev->in_flight, 0);
+ 	atomic_set(&sdev->fixup_cnt, 0);
  	atomic_set(&sdev->cancel_req, 0);
 -	sdev->csum_size = btrfs_super_csum_size(&fs_info->super_copy);
 +	sdev->csum_size = btrfs_super_csum_size(fs_info->super_copy);
  	INIT_LIST_HEAD(&sdev->csum_list);
  
  	spin_lock_init(&sdev->list_lock);
@@@ -743,11 -1136,7 +1132,11 @@@ static noinline_for_stack int scrub_str
  	u64 physical;
  	u64 logical;
  	u64 generation;
- 	u64 mirror_num;
+ 	int mirror_num;
 +	struct reada_control *reada1;
 +	struct reada_control *reada2;
 +	struct btrfs_key key_start;
 +	struct btrfs_key key_end;
  
  	u64 increment = map->stripe_len;
  	u64 offset;