From 8b7128429235d9bd72cfd5ed20c77c4f3118f744 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Wed, 11 Jun 2008 16:50:36 -0400 Subject: Btrfs: Add async worker threads for pre and post IO checksumming Btrfs has been using workqueues to spread the checksumming load across other CPUs in the system. But, workqueues only schedule work on the same CPU that queued the work, giving them a limited benefit for systems with higher CPU counts. This code adds a generic facility to schedule work with pools of kthreads, and changes the bio submission code to queue bios up. The queueing is important to make sure large numbers of procs on the system don't turn streaming workloads into random workloads by sending IO down concurrently. The end result of all of this is much higher performance (and CPU usage) when doing checksumming on large machines. Two worker pools are created, one for writes and one for endio processing. The two could deadlock if we tried to service both from a single pool. Signed-off-by: Chris Mason --- fs/btrfs/async-thread.h | 78 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 78 insertions(+) create mode 100644 fs/btrfs/async-thread.h (limited to 'fs/btrfs/async-thread.h') diff --git a/fs/btrfs/async-thread.h b/fs/btrfs/async-thread.h new file mode 100644 index 00000000000..52fc9da0f9e --- /dev/null +++ b/fs/btrfs/async-thread.h @@ -0,0 +1,78 @@ +/* + * Copyright (C) 2007 Oracle. 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. + */ + +#ifndef __BTRFS_ASYNC_THREAD_ +#define __BTRFS_ASYNC_THREAD_ + +struct btrfs_worker_thread; + +/* + * This is similar to a workqueue, but it is meant to spread the operations + * across all available cpus instead of just the CPU that was used to + * queue the work. There is also some batching introduced to try and + * cut down on context switches. + * + * By default threads are added on demand up to 2 * the number of cpus. + * Changing struct btrfs_workers->max_workers is one way to prevent + * demand creation of kthreads. + * + * the basic model of these worker threads is to embed a btrfs_work + * structure in your own data struct, and use container_of in a + * work function to get back to your data struct. + */ +struct btrfs_work { + /* + * only func should be set to the function you want called + * your work struct is passed as the only arg + */ + void (*func)(struct btrfs_work *work); + + /* + * flags should be set to zero. It is used to make sure the + * struct is only inserted once into the list. + */ + unsigned long flags; + + /* don't touch these */ + struct btrfs_worker_thread *worker; + struct list_head list; +}; + +struct btrfs_workers { + /* current number of running workers */ + int num_workers; + + /* max number of workers allowed. changed by btrfs_start_workers */ + int max_workers; + + /* list with all the work threads */ + struct list_head worker_list; + + /* the last worker thread to have something queued */ + struct btrfs_worker_thread *last; + + /* lock for finding the next worker thread to queue on */ + spinlock_t lock; +}; + +int btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work); +int btrfs_start_workers(struct btrfs_workers *workers, int num_workers); +int btrfs_stop_workers(struct btrfs_workers *workers); +void btrfs_init_workers(struct btrfs_workers *workers, int max); +int btrfs_requeue_work(struct btrfs_work *work); +#endif -- cgit v1.2.3-70-g09d2 From 35d8ba66294ff2a53c17337a1aa1ff6739492f41 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Wed, 11 Jun 2008 20:21:24 -0400 Subject: Btrfs: Worker thread optimizations This changes the worker thread pool to maintain a list of idle threads, avoiding a complex search for a good thread to wake up. Threads have two states: idle - we try to reuse the last thread used in hopes of improving the batching ratios busy - each time a new work item is added to a busy task, the task is rotated to the end of the line. Signed-off-by: Chris Mason --- fs/btrfs/async-thread.c | 100 +++++++++++++++++++++++++++++++++--------------- fs/btrfs/async-thread.h | 7 ++-- 2 files changed, 73 insertions(+), 34 deletions(-) (limited to 'fs/btrfs/async-thread.h') diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c index 8b9e2cf5060..8d4cc4679d5 100644 --- a/fs/btrfs/async-thread.c +++ b/fs/btrfs/async-thread.c @@ -34,6 +34,9 @@ * One of these is allocated per thread. */ struct btrfs_worker_thread { + /* pool we belong to */ + struct btrfs_workers *workers; + /* list of struct btrfs_work that are waiting for service */ struct list_head pending; @@ -51,8 +54,44 @@ struct btrfs_worker_thread { /* set to non-zero when this thread is already awake and kicking */ int working; + + /* are we currently idle */ + int idle; }; +/* + * helper function to move a thread onto the idle list after it + * has finished some requests. + */ +static void check_idle_worker(struct btrfs_worker_thread *worker) +{ + if (!worker->idle && atomic_read(&worker->num_pending) < + worker->workers->idle_thresh / 2) { + unsigned long flags; + spin_lock_irqsave(&worker->workers->lock, flags); + worker->idle = 1; + list_move(&worker->worker_list, &worker->workers->idle_list); + spin_unlock_irqrestore(&worker->workers->lock, flags); + } +} + +/* + * helper function to move a thread off the idle list after new + * pending work is added. + */ +static void check_busy_worker(struct btrfs_worker_thread *worker) +{ + if (worker->idle && atomic_read(&worker->num_pending) >= + worker->workers->idle_thresh) { + unsigned long flags; + spin_lock_irqsave(&worker->workers->lock, flags); + worker->idle = 0; + list_move_tail(&worker->worker_list, + &worker->workers->worker_list); + spin_unlock_irqrestore(&worker->workers->lock, flags); + } +} + /* * main loop for servicing work items */ @@ -76,6 +115,7 @@ static int worker_loop(void *arg) atomic_dec(&worker->num_pending); spin_lock_irq(&worker->lock); + check_idle_worker(worker); } worker->working = 0; if (freezing(current)) { @@ -98,6 +138,7 @@ int btrfs_stop_workers(struct btrfs_workers *workers) struct list_head *cur; struct btrfs_worker_thread *worker; + list_splice_init(&workers->idle_list, &workers->worker_list); while(!list_empty(&workers->worker_list)) { cur = workers->worker_list.next; worker = list_entry(cur, struct btrfs_worker_thread, @@ -116,9 +157,10 @@ void btrfs_init_workers(struct btrfs_workers *workers, int max) { workers->num_workers = 0; INIT_LIST_HEAD(&workers->worker_list); - workers->last = NULL; + INIT_LIST_HEAD(&workers->idle_list); spin_lock_init(&workers->lock); workers->max_workers = max; + workers->idle_thresh = 64; } /* @@ -143,14 +185,14 @@ int btrfs_start_workers(struct btrfs_workers *workers, int num_workers) spin_lock_init(&worker->lock); atomic_set(&worker->num_pending, 0); worker->task = kthread_run(worker_loop, worker, "btrfs"); + worker->workers = workers; if (IS_ERR(worker->task)) { ret = PTR_ERR(worker->task); goto fail; } spin_lock_irq(&workers->lock); - list_add_tail(&worker->worker_list, &workers->worker_list); - workers->last = worker; + list_add_tail(&worker->worker_list, &workers->idle_list); workers->num_workers++; spin_unlock_irq(&workers->lock); } @@ -169,42 +211,30 @@ static struct btrfs_worker_thread *next_worker(struct btrfs_workers *workers) { struct btrfs_worker_thread *worker; struct list_head *next; - struct list_head *start; int enforce_min = workers->num_workers < workers->max_workers; - /* start with the last thread if it isn't busy */ - worker = workers->last; - if (atomic_read(&worker->num_pending) < 64) - goto done; - - next = worker->worker_list.next; - start = &worker->worker_list; - /* - * check all the workers for someone that is bored. FIXME, do - * something smart here + * if we find an idle thread, don't move it to the end of the + * idle list. This improves the chance that the next submission + * will reuse the same thread, and maybe catch it while it is still + * working */ - while(next != start) { - if (next == &workers->worker_list) { - next = workers->worker_list.next; - continue; - } + if (!list_empty(&workers->idle_list)) { + next = workers->idle_list.next; worker = list_entry(next, struct btrfs_worker_thread, worker_list); - if (atomic_read(&worker->num_pending) < 64 || !enforce_min) - goto done; - next = next->next; + return worker; } + if (enforce_min || list_empty(&workers->worker_list)) + return NULL; + /* - * nobody was bored, if we're already at the max thread count, - * use the last thread + * if we pick a busy task, move the task to the end of the list. + * hopefully this will keep things somewhat evenly balanced */ - if (!enforce_min || atomic_read(&workers->last->num_pending) < 64) { - return workers->last; - } - return NULL; -done: - workers->last = worker; + next = workers->worker_list.next; + worker = list_entry(next, struct btrfs_worker_thread, worker_list); + list_move_tail(next, &workers->worker_list); return worker; } @@ -221,11 +251,17 @@ again: if (!worker) { spin_lock_irqsave(&workers->lock, flags); if (workers->num_workers >= workers->max_workers) { + struct list_head *fallback = NULL; /* * we have failed to find any workers, just * return the force one */ - worker = list_entry(workers->worker_list.next, + if (!list_empty(&workers->worker_list)) + fallback = workers->worker_list.next; + if (!list_empty(&workers->idle_list)) + fallback = workers->idle_list.next; + BUG_ON(!fallback); + worker = list_entry(fallback, struct btrfs_worker_thread, worker_list); spin_unlock_irqrestore(&workers->lock, flags); } else { @@ -254,6 +290,7 @@ int btrfs_requeue_work(struct btrfs_work *work) spin_lock_irqsave(&worker->lock, flags); atomic_inc(&worker->num_pending); list_add_tail(&work->list, &worker->pending); + check_busy_worker(worker); spin_unlock_irqrestore(&worker->lock, flags); out: return 0; @@ -276,6 +313,7 @@ int btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work) spin_lock_irqsave(&worker->lock, flags); atomic_inc(&worker->num_pending); + check_busy_worker(worker); list_add_tail(&work->list, &worker->pending); /* diff --git a/fs/btrfs/async-thread.h b/fs/btrfs/async-thread.h index 52fc9da0f9e..3436ff89759 100644 --- a/fs/btrfs/async-thread.h +++ b/fs/btrfs/async-thread.h @@ -60,11 +60,12 @@ struct btrfs_workers { /* max number of workers allowed. changed by btrfs_start_workers */ int max_workers; + /* once a worker has this many requests or fewer, it is idle */ + int idle_thresh; + /* list with all the work threads */ struct list_head worker_list; - - /* the last worker thread to have something queued */ - struct btrfs_worker_thread *last; + struct list_head idle_list; /* lock for finding the next worker thread to queue on */ spinlock_t lock; -- cgit v1.2.3-70-g09d2 From 5443be45f5cb57d02fd895a0bcaf7e7d9890b1df Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Fri, 15 Aug 2008 15:34:16 -0400 Subject: Btrfs: Give all the worker threads descriptive names Signed-off-by: Chris Mason --- fs/btrfs/async-thread.c | 7 +++++-- fs/btrfs/async-thread.h | 5 ++++- fs/btrfs/disk-io.c | 22 +++++++++++++++------- 3 files changed, 24 insertions(+), 10 deletions(-) (limited to 'fs/btrfs/async-thread.h') diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c index bc2980c433e..5f2f5a8c228 100644 --- a/fs/btrfs/async-thread.c +++ b/fs/btrfs/async-thread.c @@ -153,7 +153,7 @@ int btrfs_stop_workers(struct btrfs_workers *workers) /* * simple init on struct btrfs_workers */ -void btrfs_init_workers(struct btrfs_workers *workers, int max) +void btrfs_init_workers(struct btrfs_workers *workers, char *name, int max) { workers->num_workers = 0; INIT_LIST_HEAD(&workers->worker_list); @@ -161,6 +161,7 @@ void btrfs_init_workers(struct btrfs_workers *workers, int max) spin_lock_init(&workers->lock); workers->max_workers = max; workers->idle_thresh = 32; + workers->name = name; } /* @@ -184,7 +185,9 @@ int btrfs_start_workers(struct btrfs_workers *workers, int num_workers) INIT_LIST_HEAD(&worker->worker_list); spin_lock_init(&worker->lock); atomic_set(&worker->num_pending, 0); - worker->task = kthread_run(worker_loop, worker, "btrfs"); + worker->task = kthread_run(worker_loop, worker, + "btrfs-%s-%d", workers->name, + workers->num_workers + i); worker->workers = workers; if (IS_ERR(worker->task)) { kfree(worker); diff --git a/fs/btrfs/async-thread.h b/fs/btrfs/async-thread.h index 3436ff89759..43e44d115dd 100644 --- a/fs/btrfs/async-thread.h +++ b/fs/btrfs/async-thread.h @@ -69,11 +69,14 @@ struct btrfs_workers { /* lock for finding the next worker thread to queue on */ spinlock_t lock; + + /* extra name for this worker */ + char *name; }; int btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work); int btrfs_start_workers(struct btrfs_workers *workers, int num_workers); int btrfs_stop_workers(struct btrfs_workers *workers); -void btrfs_init_workers(struct btrfs_workers *workers, int max); +void btrfs_init_workers(struct btrfs_workers *workers, char *name, int max); int btrfs_requeue_work(struct btrfs_work *work); #endif diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 9601b13c7d7..1bf210dadef 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -492,11 +492,11 @@ static int __btree_submit_bio_hook(struct inode *inode, int rw, struct bio *bio, /* * when we're called for a write, we're already in the async - * submission context. Just jump ingo btrfs_map_bio + * submission context. Just jump into btrfs_map_bio */ if (rw & (1 << BIO_RW)) { return btrfs_map_bio(BTRFS_I(inode)->root, rw, bio, - mirror_num, 0); + mirror_num, 1); } /* @@ -528,6 +528,12 @@ static int btree_writepage(struct page *page, struct writeback_control *wbc) { struct extent_io_tree *tree; tree = &BTRFS_I(page->mapping->host)->io_tree; + + if (current->flags & PF_MEMALLOC) { + redirty_page_for_writepage(wbc, page); + unlock_page(page); + return 0; + } return extent_write_full_page(tree, page, btree_get_extent, wbc); } @@ -1363,8 +1369,9 @@ struct btrfs_root *open_ctree(struct super_block *sb, * queue work function gets called at interrupt time, and so it * cannot dynamically grow. */ - btrfs_init_workers(&fs_info->workers, fs_info->thread_pool_size); - btrfs_init_workers(&fs_info->submit_workers, + btrfs_init_workers(&fs_info->workers, "worker", + fs_info->thread_pool_size); + btrfs_init_workers(&fs_info->submit_workers, "submit", min_t(u64, fs_devices->num_devices, fs_info->thread_pool_size)); @@ -1374,9 +1381,10 @@ struct btrfs_root *open_ctree(struct super_block *sb, */ fs_info->submit_workers.idle_thresh = 64; - btrfs_init_workers(&fs_info->fixup_workers, 1); - btrfs_init_workers(&fs_info->endio_workers, fs_info->thread_pool_size); - btrfs_init_workers(&fs_info->endio_write_workers, + btrfs_init_workers(&fs_info->fixup_workers, "fixup", 1); + btrfs_init_workers(&fs_info->endio_workers, "endio", + fs_info->thread_pool_size); + btrfs_init_workers(&fs_info->endio_write_workers, "endio-write", fs_info->thread_pool_size); /* -- cgit v1.2.3-70-g09d2 From d352ac68148b69937d39ca5d48bcc4478e118dbf Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Mon, 29 Sep 2008 15:18:18 -0400 Subject: Btrfs: add and improve comments This improves the comments at the top of many functions. It didn't dive into the guts of functions because I was trying to avoid merging problems with the new allocator and back reference work. extent-tree.c and volumes.c were both skipped, and there is definitely more work todo in cleaning and commenting the code. Signed-off-by: Chris Mason --- fs/btrfs/Makefile | 2 +- fs/btrfs/TODO | 20 ----- fs/btrfs/async-thread.c | 10 ++- fs/btrfs/async-thread.h | 7 +- fs/btrfs/bit-radix.c | 130 --------------------------------- fs/btrfs/bit-radix.h | 33 --------- fs/btrfs/btrfs_inode.h | 54 +++++++++++++- fs/btrfs/crc32c.h | 18 +++++ fs/btrfs/ctree.c | 127 +++++++++++++++++++++++++++++--- fs/btrfs/ctree.h | 1 - fs/btrfs/dir-item.c | 41 +++++++++++ fs/btrfs/disk-io.c | 33 ++++++++- fs/btrfs/extent_io.c | 34 ++++++++- fs/btrfs/extent_map.c | 10 +++ fs/btrfs/file.c | 44 ++++++++++- fs/btrfs/inode.c | 189 +++++++++++++++++++++++++++++++----------------- fs/btrfs/locking.c | 13 ++++ fs/btrfs/ordered-data.c | 19 ++++- fs/btrfs/ref-cache.c | 26 +++++++ fs/btrfs/ref-cache.h | 3 + fs/btrfs/root-tree.c | 21 +++++- fs/btrfs/struct-funcs.c | 21 ++++++ fs/btrfs/super.c | 3 + fs/btrfs/transaction.c | 67 ++++++++++++++++- fs/btrfs/tree-defrag.c | 4 + 25 files changed, 653 insertions(+), 277 deletions(-) delete mode 100644 fs/btrfs/TODO delete mode 100644 fs/btrfs/bit-radix.c delete mode 100644 fs/btrfs/bit-radix.h (limited to 'fs/btrfs/async-thread.h') diff --git a/fs/btrfs/Makefile b/fs/btrfs/Makefile index d5c28557fba..48b7909ca8d 100644 --- a/fs/btrfs/Makefile +++ b/fs/btrfs/Makefile @@ -4,7 +4,7 @@ ifneq ($(KERNELRELEASE),) obj-m := btrfs.o btrfs-y := super.o ctree.o extent-tree.o print-tree.o root-tree.o dir-item.o \ file-item.o inode-item.o inode-map.o disk-io.o \ - transaction.o bit-radix.o inode.o file.o tree-defrag.o \ + transaction.o inode.o file.o tree-defrag.o \ 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 \ ref-cache.o export.o tree-log.o acl.o free-space-cache.o diff --git a/fs/btrfs/TODO b/fs/btrfs/TODO deleted file mode 100644 index d9b6d38c603..00000000000 --- a/fs/btrfs/TODO +++ /dev/null @@ -1,20 +0,0 @@ -* cleanup, add more error checking, get rid of BUG_ONs -* Fix ENOSPC handling -* Make allocator smarter -* add a block group to struct inode -* Do actual block accounting -* Check compat and incompat flags on the inode -* Get rid of struct ctree_path, limiting tree levels held at one time -* Add generation number to key pointer in nodes -* Add generation number to inode -* forbid cross subvolume renames and hardlinks -* Release -* Do real tree locking -* Add extent mirroring (backup copies of blocks) -* Add fancy interface to get access to incremental backups -* Add fancy striped extents to make big reads faster -* Use relocation to try and fix write errors -* Make allocator much smarter -* xattrs (directory streams for regular files) -* Scrub & defrag - diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c index 4e780b279de..04fb9702d14 100644 --- a/fs/btrfs/async-thread.c +++ b/fs/btrfs/async-thread.c @@ -231,17 +231,25 @@ static struct btrfs_worker_thread *next_worker(struct btrfs_workers *workers) /* * if we pick a busy task, move the task to the end of the list. - * hopefully this will keep things somewhat evenly balanced + * hopefully this will keep things somewhat evenly balanced. + * Do the move in batches based on the sequence number. This groups + * requests submitted at roughly the same time onto the same worker. */ next = workers->worker_list.next; worker = list_entry(next, struct btrfs_worker_thread, worker_list); atomic_inc(&worker->num_pending); worker->sequence++; + if (worker->sequence % workers->idle_thresh == 0) list_move_tail(next, &workers->worker_list); return worker; } +/* + * selects a worker thread to take the next job. This will either find + * an idle worker, start a new worker up to the max count, or just return + * one of the existing busy workers. + */ static struct btrfs_worker_thread *find_worker(struct btrfs_workers *workers) { struct btrfs_worker_thread *worker; diff --git a/fs/btrfs/async-thread.h b/fs/btrfs/async-thread.h index 43e44d115dd..4ec9a2ee0f9 100644 --- a/fs/btrfs/async-thread.h +++ b/fs/btrfs/async-thread.h @@ -63,14 +63,17 @@ struct btrfs_workers { /* once a worker has this many requests or fewer, it is idle */ int idle_thresh; - /* list with all the work threads */ + /* list with all the work threads. The workers on the idle thread + * may be actively servicing jobs, but they haven't yet hit the + * idle thresh limit above. + */ struct list_head worker_list; struct list_head idle_list; /* lock for finding the next worker thread to queue on */ spinlock_t lock; - /* extra name for this worker */ + /* extra name for this worker, used for current->name */ char *name; }; diff --git a/fs/btrfs/bit-radix.c b/fs/btrfs/bit-radix.c deleted file mode 100644 index e8bf876db39..00000000000 --- a/fs/btrfs/bit-radix.c +++ /dev/null @@ -1,130 +0,0 @@ -/* - * Copyright (C) 2007 Oracle. 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 "bit-radix.h" - -#define BIT_ARRAY_BYTES 256 -#define BIT_RADIX_BITS_PER_ARRAY ((BIT_ARRAY_BYTES - sizeof(unsigned long)) * 8) - -extern struct kmem_cache *btrfs_bit_radix_cachep; -int set_radix_bit(struct radix_tree_root *radix, unsigned long bit) -{ - unsigned long *bits; - unsigned long slot; - int bit_slot; - int ret; - - slot = bit / BIT_RADIX_BITS_PER_ARRAY; - bit_slot = bit % BIT_RADIX_BITS_PER_ARRAY; - - bits = radix_tree_lookup(radix, slot); - if (!bits) { - bits = kmem_cache_alloc(btrfs_bit_radix_cachep, GFP_NOFS); - if (!bits) - return -ENOMEM; - memset(bits + 1, 0, BIT_ARRAY_BYTES - sizeof(unsigned long)); - bits[0] = slot; - ret = radix_tree_insert(radix, slot, bits); - if (ret) - return ret; - } - ret = test_and_set_bit(bit_slot, bits + 1); - if (ret < 0) - ret = 1; - return ret; -} - -int test_radix_bit(struct radix_tree_root *radix, unsigned long bit) -{ - unsigned long *bits; - unsigned long slot; - int bit_slot; - - slot = bit / BIT_RADIX_BITS_PER_ARRAY; - bit_slot = bit % BIT_RADIX_BITS_PER_ARRAY; - - bits = radix_tree_lookup(radix, slot); - if (!bits) - return 0; - return test_bit(bit_slot, bits + 1); -} - -int clear_radix_bit(struct radix_tree_root *radix, unsigned long bit) -{ - unsigned long *bits; - unsigned long slot; - int bit_slot; - int i; - int empty = 1; - - slot = bit / BIT_RADIX_BITS_PER_ARRAY; - bit_slot = bit % BIT_RADIX_BITS_PER_ARRAY; - - bits = radix_tree_lookup(radix, slot); - if (!bits) - return 0; - clear_bit(bit_slot, bits + 1); - for (i = 1; i < BIT_ARRAY_BYTES / sizeof(unsigned long); i++) { - if (bits[i]) { - empty = 0; - break; - } - } - if (empty) { - bits = radix_tree_delete(radix, slot); - BUG_ON(!bits); - kmem_cache_free(btrfs_bit_radix_cachep, bits); - } - return 0; -} - -int find_first_radix_bit(struct radix_tree_root *radix, unsigned long *retbits, - unsigned long start, int nr) -{ - unsigned long *bits; - unsigned long *gang[4]; - int found; - int ret; - int i; - int total_found = 0; - unsigned long slot; - - slot = start / BIT_RADIX_BITS_PER_ARRAY; - ret = radix_tree_gang_lookup(radix, (void **)gang, slot, - ARRAY_SIZE(gang)); - found = start % BIT_RADIX_BITS_PER_ARRAY; - for (i = 0; i < ret && nr > 0; i++) { - bits = gang[i]; - while(nr > 0) { - found = find_next_bit(bits + 1, - BIT_RADIX_BITS_PER_ARRAY, - found); - if (found < BIT_RADIX_BITS_PER_ARRAY) { - *retbits = bits[0] * - BIT_RADIX_BITS_PER_ARRAY + found; - retbits++; - nr--; - total_found++; - found++; - } else - break; - } - found = 0; - } - return total_found; -} diff --git a/fs/btrfs/bit-radix.h b/fs/btrfs/bit-radix.h deleted file mode 100644 index c100f54d5c3..00000000000 --- a/fs/btrfs/bit-radix.h +++ /dev/null @@ -1,33 +0,0 @@ -/* - * Copyright (C) 2007 Oracle. 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. - */ - -#ifndef __BIT_RADIX__ -#define __BIT_RADIX__ -#include - -int set_radix_bit(struct radix_tree_root *radix, unsigned long bit); -int test_radix_bit(struct radix_tree_root *radix, unsigned long bit); -int clear_radix_bit(struct radix_tree_root *radix, unsigned long bit); -int find_first_radix_bit(struct radix_tree_root *radix, unsigned long *retbits, - unsigned long start, int nr); - -static inline void init_bit_radix(struct radix_tree_root *radix) -{ - INIT_RADIX_TREE(radix, GFP_NOFS); -} -#endif diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h index 0577fda2168..0b2e623cf42 100644 --- a/fs/btrfs/btrfs_inode.h +++ b/fs/btrfs/btrfs_inode.h @@ -25,27 +25,58 @@ /* in memory btrfs inode */ struct btrfs_inode { + /* which subvolume this inode belongs to */ struct btrfs_root *root; + + /* the block group preferred for allocations. This pointer is buggy + * and needs to be replaced with a bytenr instead + */ struct btrfs_block_group_cache *block_group; + + /* key used to find this inode on disk. This is used by the code + * to read in roots of subvolumes + */ struct btrfs_key location; + + /* the extent_tree has caches of all the extent mappings to disk */ struct extent_map_tree extent_tree; + + /* the io_tree does range state (DIRTY, LOCKED etc) */ struct extent_io_tree io_tree; + + /* special utility tree used to record which mirrors have already been + * tried when checksums fail for a given block + */ struct extent_io_tree io_failure_tree; + + /* held while inserting checksums to avoid races */ struct mutex csum_mutex; + + /* held while inesrting or deleting extents from files */ struct mutex extent_mutex; + + /* held while logging the inode in tree-log.c */ struct mutex log_mutex; - struct inode vfs_inode; + + /* used to order data wrt metadata */ struct btrfs_ordered_inode_tree ordered_tree; + /* standard acl pointers */ struct posix_acl *i_acl; struct posix_acl *i_default_acl; /* for keeping track of orphaned inodes */ struct list_head i_orphan; + /* list of all the delalloc inodes in the FS. There are times we need + * to write all the delalloc pages to disk, and this list is used + * to walk them all. + */ struct list_head delalloc_inodes; - /* full 64 bit generation number */ + /* full 64 bit generation number, struct vfs_inode doesn't have a big + * enough field for this. + */ u64 generation; /* @@ -57,10 +88,25 @@ struct btrfs_inode { */ u64 logged_trans; - /* trans that last made a change that should be fully fsync'd */ + /* + * trans that last made a change that should be fully fsync'd. This + * gets reset to zero each time the inode is logged + */ u64 log_dirty_trans; + + /* total number of bytes pending delalloc, used by stat to calc the + * real block usage of the file + */ u64 delalloc_bytes; + + /* + * the size of the file stored in the metadata on disk. data=ordered + * means the in-memory i_size might be larger than the size on disk + * because not all the blocks are written yet. + */ u64 disk_i_size; + + /* flags field from the on disk inode */ u32 flags; /* @@ -68,6 +114,8 @@ struct btrfs_inode { * number for new files that are created */ u64 index_cnt; + + struct inode vfs_inode; }; static inline struct btrfs_inode *BTRFS_I(struct inode *inode) diff --git a/fs/btrfs/crc32c.h b/fs/btrfs/crc32c.h index 4f0fefed132..1eaf11d334f 100644 --- a/fs/btrfs/crc32c.h +++ b/fs/btrfs/crc32c.h @@ -1,3 +1,21 @@ +/* + * Copyright (C) 2008 Oracle. 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. + */ + #ifndef __BTRFS_CRC32C__ #define __BTRFS_CRC32C__ #include diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 50e81f43e6d..ff3261ff2e1 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -1,5 +1,5 @@ /* - * Copyright (C) 2007 Oracle. All rights reserved. + * Copyright (C) 2007,2008 Oracle. All rights reserved. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public @@ -54,12 +54,19 @@ struct btrfs_path *btrfs_alloc_path(void) return path; } +/* this also releases the path */ void btrfs_free_path(struct btrfs_path *p) { btrfs_release_path(NULL, p); kmem_cache_free(btrfs_path_cachep, p); } +/* + * path release drops references on the extent buffers in the path + * and it drops any locks held by this path + * + * It is safe to call this on paths that no locks or extent buffers held. + */ void noinline btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p) { int i; @@ -77,6 +84,16 @@ void noinline btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p) } } +/* + * safely gets a reference on the root node of a tree. A lock + * is not taken, so a concurrent writer may put a different node + * at the root of the tree. See btrfs_lock_root_node for the + * looping required. + * + * The extent buffer returned by this has a reference taken, so + * it won't disappear. It may stop being the root of the tree + * at any time because there are no locks held. + */ struct extent_buffer *btrfs_root_node(struct btrfs_root *root) { struct extent_buffer *eb; @@ -87,6 +104,10 @@ struct extent_buffer *btrfs_root_node(struct btrfs_root *root) return eb; } +/* loop around taking references on and locking the root node of the + * tree until you end up with a lock on the root. A locked buffer + * is returned, with a reference held. + */ struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root) { struct extent_buffer *eb; @@ -108,6 +129,10 @@ struct extent_buffer *btrfs_lock_root_node(struct btrfs_root *root) return eb; } +/* cowonly root (everything not a reference counted cow subvolume), just get + * put onto a simple dirty list. transaction.c walks this to make sure they + * get properly updated on disk. + */ static void add_root_to_dirty_list(struct btrfs_root *root) { if (root->track_dirty && list_empty(&root->dirty_list)) { @@ -116,6 +141,11 @@ static void add_root_to_dirty_list(struct btrfs_root *root) } } +/* + * used by snapshot creation to make a copy of a root for a tree with + * a given objectid. The buffer with the new root node is returned in + * cow_ret, and this func returns zero on success or a negative error code. + */ int btrfs_copy_root(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *buf, @@ -167,6 +197,22 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans, return 0; } +/* + * does the dirty work in cow of a single block. The parent block + * (if supplied) is updated to point to the new cow copy. The new + * buffer is marked dirty and returned locked. If you modify the block + * it needs to be marked dirty again. + * + * search_start -- an allocation hint for the new block + * + * empty_size -- a hint that you plan on doing more cow. This is the size in bytes + * the allocator should try to find free next to the block it returns. This is + * just a hint and may be ignored by the allocator. + * + * prealloc_dest -- if you have already reserved a destination for the cow, + * this uses that block instead of allocating a new one. btrfs_alloc_reserved_extent + * is used to finish the allocation. + */ int noinline __btrfs_cow_block(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *buf, @@ -311,6 +357,11 @@ int noinline __btrfs_cow_block(struct btrfs_trans_handle *trans, return 0; } +/* + * cows a single block, see __btrfs_cow_block for the real work. + * This version of it has extra checks so that a block isn't cow'd more than + * once per transaction, as long as it hasn't been written yet + */ int noinline btrfs_cow_block(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *buf, struct extent_buffer *parent, int parent_slot, @@ -347,6 +398,10 @@ int noinline btrfs_cow_block(struct btrfs_trans_handle *trans, return ret; } +/* + * helper function for defrag to decide if two blocks pointed to by a + * node are actually close by + */ static int close_blocks(u64 blocknr, u64 other, u32 blocksize) { if (blocknr < other && other - (blocknr + blocksize) < 32768) @@ -381,6 +436,11 @@ static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2) } +/* + * this is used by the defrag code to go through all the + * leaves pointed to by a node and reallocate them so that + * disk order is close to key order + */ int btrfs_realloc_node(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct extent_buffer *parent, int start_slot, int cache_only, u64 *last_ret, @@ -521,6 +581,10 @@ static inline unsigned int leaf_data_end(struct btrfs_root *root, return btrfs_item_offset_nr(leaf, nr - 1); } +/* + * extra debugging checks to make sure all the items in a key are + * well formed and in the proper order + */ static int check_node(struct btrfs_root *root, struct btrfs_path *path, int level) { @@ -561,6 +625,10 @@ static int check_node(struct btrfs_root *root, struct btrfs_path *path, return 0; } +/* + * extra checking to make sure all the items in a leaf are + * well formed and in the proper order + */ static int check_leaf(struct btrfs_root *root, struct btrfs_path *path, int level) { @@ -782,6 +850,10 @@ static int bin_search(struct extent_buffer *eb, struct btrfs_key *key, return -1; } +/* given a node and slot number, this reads the blocks it points to. The + * extent buffer is returned with a reference taken (but unlocked). + * NULL is returned on error. + */ static noinline struct extent_buffer *read_node_slot(struct btrfs_root *root, struct extent_buffer *parent, int slot) { @@ -798,6 +870,11 @@ static noinline struct extent_buffer *read_node_slot(struct btrfs_root *root, btrfs_node_ptr_generation(parent, slot)); } +/* + * node level balancing, used to make sure nodes are in proper order for + * item deletion. We balance from the top down, so we have to make sure + * that a deletion won't leave an node completely empty later on. + */ static noinline int balance_level(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, int level) @@ -1024,7 +1101,10 @@ enospc: return ret; } -/* returns zero if the push worked, non-zero otherwise */ +/* Node balancing for insertion. Here we only split or push nodes around + * when they are completely full. This is also done top down, so we + * have to be pessimistic. + */ static int noinline push_nodes_for_insert(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, int level) @@ -1150,7 +1230,8 @@ static int noinline push_nodes_for_insert(struct btrfs_trans_handle *trans, } /* - * readahead one full node of leaves + * readahead one full node of leaves, finding things that are close + * to the block in 'slot', and triggering ra on them. */ static noinline void reada_for_search(struct btrfs_root *root, struct btrfs_path *path, @@ -1226,6 +1307,19 @@ static noinline void reada_for_search(struct btrfs_root *root, } } +/* + * when we walk down the tree, it is usually safe to unlock the higher layers in + * the tree. The exceptions are when our path goes through slot 0, because operations + * on the tree might require changing key pointers higher up in the tree. + * + * callers might also have set path->keep_locks, which tells this code to + * keep the lock if the path points to the last slot in the block. This is + * part of walking through the tree, and selecting the next slot in the higher + * block. + * + * lowest_unlock sets the lowest level in the tree we're allowed to unlock. + * so if lowest_unlock is 1, level 0 won't be unlocked + */ static noinline void unlock_up(struct btrfs_path *path, int level, int lowest_unlock) { @@ -2705,6 +2799,12 @@ again: return ret; } +/* + * make the item pointed to by the path smaller. new_size indicates + * how small to make it, and from_end tells us if we just chop bytes + * off the end of the item or if we shift the item to chop bytes off + * the front. + */ int btrfs_truncate_item(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, @@ -2818,6 +2918,9 @@ int btrfs_truncate_item(struct btrfs_trans_handle *trans, return ret; } +/* + * make the item pointed to by the path bigger, data_size is the new size. + */ int btrfs_extend_item(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, u32 data_size) @@ -2897,7 +3000,7 @@ int btrfs_extend_item(struct btrfs_trans_handle *trans, } /* - * Given a key and some data, insert an item into the tree. + * Given a key and some data, insert items into the tree. * This does all the path init required, making room in the tree if needed. */ int btrfs_insert_empty_items(struct btrfs_trans_handle *trans, @@ -3046,9 +3149,8 @@ int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root /* * delete the pointer from a given node. * - * If the delete empties a node, the node is removed from the tree, - * continuing all the way the root if required. The root is converted into - * a leaf if all the nodes are emptied. + * the tree should have been previously balanced so the deletion does not + * empty a node. */ static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, int level, int slot) @@ -3233,6 +3335,9 @@ int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root, * search the tree again to find a leaf with lesser keys * returns 0 if it found something or 1 if there are no lesser leaves. * returns < 0 on io errors. + * + * This may release the path, and so you may lose any locks held at the + * time you call it. */ int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path) { @@ -3265,9 +3370,7 @@ int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path) /* * A helper function to walk down the tree starting at min_key, and looking * for nodes or leaves that are either in cache or have a minimum - * transaction id. This is used by the btree defrag code, but could - * also be used to search for blocks that have changed since a given - * transaction id. + * transaction id. This is used by the btree defrag code, and tree logging * * This does not cow, but it does stuff the starting key it finds back * into min_key, so you can call btrfs_search_slot with cow=1 on the @@ -3279,6 +3382,10 @@ int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path) * This honors path->lowest_level to prevent descent past a given level * of the tree. * + * min_trans indicates the oldest transaction that you are interested + * in walking through. Any nodes or leaves older than min_trans are + * skipped over (without reading them). + * * returns zero if something useful was found, < 0 on error and 1 if there * was nothing in the tree that matched the search criteria. */ diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 0079b60b18f..ded1643c027 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -27,7 +27,6 @@ #include #include #include -#include "bit-radix.h" #include "extent_io.h" #include "extent_map.h" #include "async-thread.h" diff --git a/fs/btrfs/dir-item.c b/fs/btrfs/dir-item.c index e4f30090d64..5040b71f190 100644 --- a/fs/btrfs/dir-item.c +++ b/fs/btrfs/dir-item.c @@ -21,6 +21,14 @@ #include "hash.h" #include "transaction.h" +/* + * insert a name into a directory, doing overflow properly if there is a hash + * collision. data_size indicates how big the item inserted should be. On + * success a struct btrfs_dir_item pointer is returned, otherwise it is + * an ERR_PTR. + * + * The name is not copied into the dir item, you have to do that yourself. + */ static struct btrfs_dir_item *insert_with_overflow(struct btrfs_trans_handle *trans, struct btrfs_root *root, @@ -55,6 +63,10 @@ static struct btrfs_dir_item *insert_with_overflow(struct btrfs_trans_handle return (struct btrfs_dir_item *)ptr; } +/* + * xattrs work a lot like directories, this inserts an xattr item + * into the tree + */ int btrfs_insert_xattr_item(struct btrfs_trans_handle *trans, struct btrfs_root *root, const char *name, u16 name_len, const void *data, u16 data_len, @@ -109,6 +121,13 @@ int btrfs_insert_xattr_item(struct btrfs_trans_handle *trans, return ret; } +/* + * insert a directory item in the tree, doing all the magic for + * both indexes. 'dir' indicates which objectid to insert it into, + * 'location' is the key to stuff into the directory item, 'type' is the + * type of the inode we're pointing to, and 'index' is the sequence number + * to use for the second index (if one is created). + */ int btrfs_insert_dir_item(struct btrfs_trans_handle *trans, struct btrfs_root *root, const char *name, int name_len, u64 dir, struct btrfs_key *location, u8 type, u64 index) @@ -184,6 +203,11 @@ out: return 0; } +/* + * lookup a directory item based on name. 'dir' is the objectid + * we're searching in, and 'mod' tells us if you plan on deleting the + * item (use mod < 0) or changing the options (use mod > 0) + */ struct btrfs_dir_item *btrfs_lookup_dir_item(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, u64 dir, @@ -222,6 +246,14 @@ struct btrfs_dir_item *btrfs_lookup_dir_item(struct btrfs_trans_handle *trans, return btrfs_match_dir_item_name(root, path, name, name_len); } +/* + * lookup a directory item based on index. 'dir' is the objectid + * we're searching in, and 'mod' tells us if you plan on deleting the + * item (use mod < 0) or changing the options (use mod > 0) + * + * The name is used to make sure the index really points to the name you were + * looking for. + */ struct btrfs_dir_item * btrfs_lookup_dir_index_item(struct btrfs_trans_handle *trans, struct btrfs_root *root, @@ -282,6 +314,11 @@ struct btrfs_dir_item *btrfs_lookup_xattr(struct btrfs_trans_handle *trans, return btrfs_match_dir_item_name(root, path, name, name_len); } +/* + * helper function to look at the directory item pointed to by 'path' + * this walks through all the entries in a dir item and finds one + * for a specific name. + */ struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_root *root, struct btrfs_path *path, const char *name, int name_len) @@ -313,6 +350,10 @@ struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_root *root, return NULL; } +/* + * given a pointer into a directory item, delete it. This + * handles items that have more than one entry in them. + */ int btrfs_delete_one_dir_name(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_path *path, diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 45b4f728527..5ee10d3136f 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -55,6 +55,11 @@ static int check_tree_block(struct btrfs_root *root, struct extent_buffer *buf) static struct extent_io_ops btree_extent_io_ops; static void end_workqueue_fn(struct btrfs_work *work); +/* + * end_io_wq structs are used to do processing in task context when an IO is + * complete. This is used during reads to verify checksums, and it is used + * by writes to insert metadata for new file extents after IO is complete. + */ struct end_io_wq { struct bio *bio; bio_end_io_t *end_io; @@ -66,6 +71,11 @@ struct end_io_wq { struct btrfs_work work; }; +/* + * async submit bios are used to offload expensive checksumming + * onto the worker threads. They checksum file and metadata bios + * just before they are sent down the IO stack. + */ struct async_submit_bio { struct inode *inode; struct bio *bio; @@ -76,6 +86,10 @@ struct async_submit_bio { struct btrfs_work work; }; +/* + * extents on the btree inode are pretty simple, there's one extent + * that covers the entire device + */ struct extent_map *btree_get_extent(struct inode *inode, struct page *page, size_t page_offset, u64 start, u64 len, int create) @@ -151,6 +165,10 @@ void btrfs_csum_final(u32 crc, char *result) *(__le32 *)result = ~cpu_to_le32(crc); } +/* + * compute the csum for a btree block, and either verify it or write it + * into the csum field of the block. + */ static int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf, int verify) { @@ -204,6 +222,12 @@ static int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf, return 0; } +/* + * we can't consider a given block up to date unless the transid of the + * block matches the transid in the parent node's pointer. This is how we + * detect blocks that either didn't get written at all or got written + * in the wrong place. + */ static int verify_parent_transid(struct extent_io_tree *io_tree, struct extent_buffer *eb, u64 parent_transid) { @@ -228,9 +252,12 @@ out: unlock_extent(io_tree, eb->start, eb->start + eb->len - 1, GFP_NOFS); return ret; - } +/* + * helper to read a given tree block, doing retries as required when + * the checksums don't match and we have alternate mirrors to try. + */ static int btree_read_extent_buffer_pages(struct btrfs_root *root, struct extent_buffer *eb, u64 start, u64 parent_transid) @@ -260,6 +287,10 @@ printk("read extent buffer pages failed with ret %d mirror no %d\n", ret, mirror return -EIO; } +/* + * checksum a dirty tree block before IO. This has extra checks to make + * sure we only fill in the checksum field in the first page of a multi-page block + */ int csum_dirty_buffer(struct btrfs_root *root, struct page *page) { struct extent_io_tree *tree; diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 8bd1b402f3f..563b2d12f4f 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -914,6 +914,10 @@ int wait_on_extent_writeback(struct extent_io_tree *tree, u64 start, u64 end) } EXPORT_SYMBOL(wait_on_extent_writeback); +/* + * either insert or lock state struct between start and end use mask to tell + * us if waiting is desired. + */ int lock_extent(struct extent_io_tree *tree, u64 start, u64 end, gfp_t mask) { int err; @@ -982,6 +986,13 @@ int set_range_writeback(struct extent_io_tree *tree, u64 start, u64 end) } EXPORT_SYMBOL(set_range_writeback); +/* + * find the first offset in the io tree with 'bits' set. zero is + * returned if we find something, and *start_ret and *end_ret are + * set to reflect the state struct that was found. + * + * If nothing was found, 1 is returned, < 0 on error + */ int find_first_extent_bit(struct extent_io_tree *tree, u64 start, u64 *start_ret, u64 *end_ret, int bits) { @@ -1017,6 +1028,10 @@ out: } EXPORT_SYMBOL(find_first_extent_bit); +/* find the first state struct with 'bits' set after 'start', and + * return it. tree->lock must be held. NULL will returned if + * nothing was found after 'start' + */ struct extent_state *find_first_extent_bit_state(struct extent_io_tree *tree, u64 start, int bits) { @@ -1046,8 +1061,14 @@ out: } EXPORT_SYMBOL(find_first_extent_bit_state); -u64 find_lock_delalloc_range(struct extent_io_tree *tree, - u64 *start, u64 *end, u64 max_bytes) +/* + * find a contiguous range of bytes in the file marked as delalloc, not + * more than 'max_bytes'. start and end are used to return the range, + * + * 1 is returned if we find something, 0 if nothing was in the tree + */ +static noinline u64 find_lock_delalloc_range(struct extent_io_tree *tree, + u64 *start, u64 *end, u64 max_bytes) { struct rb_node *node; struct extent_state *state; @@ -1130,6 +1151,11 @@ out: return found; } +/* + * count the number of bytes in the tree that have a given bit(s) + * set. This can be fairly slow, except for EXTENT_DIRTY which is + * cached. The total number found is returned. + */ u64 count_range_bits(struct extent_io_tree *tree, u64 *start, u64 search_end, u64 max_bytes, unsigned long bits) @@ -1245,6 +1271,10 @@ int unlock_range(struct extent_io_tree *tree, u64 start, u64 end) } EXPORT_SYMBOL(unlock_range); +/* + * set the private field for a given byte offset in the tree. If there isn't + * an extent_state there already, this does nothing. + */ int set_state_private(struct extent_io_tree *tree, u64 start, u64 private) { struct rb_node *node; diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c index 78ced11d18c..74b2a29880d 100644 --- a/fs/btrfs/extent_map.c +++ b/fs/btrfs/extent_map.c @@ -114,6 +114,10 @@ static struct rb_node *tree_insert(struct rb_root *root, u64 offset, return NULL; } +/* + * search through the tree for an extent_map with a given offset. If + * it can't be found, try to find some neighboring extents + */ static struct rb_node *__tree_search(struct rb_root *root, u64 offset, struct rb_node **prev_ret, struct rb_node **next_ret) @@ -160,6 +164,10 @@ static struct rb_node *__tree_search(struct rb_root *root, u64 offset, return NULL; } +/* + * look for an offset in the tree, and if it can't be found, return + * the first offset we can find smaller than 'offset'. + */ static inline struct rb_node *tree_search(struct rb_root *root, u64 offset) { struct rb_node *prev; @@ -170,6 +178,7 @@ static inline struct rb_node *tree_search(struct rb_root *root, u64 offset) return ret; } +/* check to see if two extent_map structs are adjacent and safe to merge */ static int mergable_maps(struct extent_map *prev, struct extent_map *next) { if (test_bit(EXTENT_FLAG_PINNED, &prev->flags)) @@ -250,6 +259,7 @@ out: } EXPORT_SYMBOL(add_extent_mapping); +/* simple helper to do math around the end of an extent, handling wrap */ static u64 range_end(u64 start, u64 len) { if (start + len < start) diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 1b7e51a9db0..3088a118448 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -41,6 +41,9 @@ #include "compat.h" +/* simple helper to fault in pages and copy. This should go away + * and be replaced with calls into generic code. + */ static int noinline btrfs_copy_from_user(loff_t pos, int num_pages, int write_bytes, struct page **prepared_pages, @@ -72,12 +75,19 @@ static int noinline btrfs_copy_from_user(loff_t pos, int num_pages, return page_fault ? -EFAULT : 0; } +/* + * unlocks pages after btrfs_file_write is done with them + */ static void noinline btrfs_drop_pages(struct page **pages, size_t num_pages) { size_t i; for (i = 0; i < num_pages; i++) { if (!pages[i]) break; + /* page checked is some magic around finding pages that + * have been modified without going through btrfs_set_page_dirty + * clear it here + */ ClearPageChecked(pages[i]); unlock_page(pages[i]); mark_page_accessed(pages[i]); @@ -85,6 +95,10 @@ static void noinline btrfs_drop_pages(struct page **pages, size_t num_pages) } } +/* this does all the hard work for inserting an inline extent into + * the btree. Any existing inline extent is extended as required to make room, + * otherwise things are inserted as required into the btree + */ static int noinline insert_inline_extent(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct inode *inode, u64 offset, size_t size, @@ -228,6 +242,14 @@ fail: return err; } +/* + * after copy_from_user, pages need to be dirtied and we need to make + * sure holes are created between the current EOF and the start of + * any next extents (if required). + * + * this also makes the decision about creating an inline extent vs + * doing real data extents, marking pages dirty and delalloc as required. + */ static int noinline dirty_and_release_pages(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct file *file, @@ -362,6 +384,10 @@ out_unlock: return err; } +/* + * this drops all the extents in the cache that intersect the range + * [start, end]. Existing extents are split as required. + */ int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end, int skip_pinned) { @@ -536,6 +562,9 @@ out: * If an extent intersects the range but is not entirely inside the range * it is either truncated or split. Anything entirely inside the range * is deleted from the tree. + * + * inline_limit is used to tell this code which offsets in the file to keep + * if they contain inline extents. */ int noinline btrfs_drop_extents(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct inode *inode, @@ -796,7 +825,9 @@ out: } /* - * this gets pages into the page cache and locks them down + * this gets pages into the page cache and locks them down, it also properly + * waits for data=ordered extents to finish before allowing the pages to be + * modified. */ static int noinline prepare_pages(struct btrfs_root *root, struct file *file, struct page **pages, size_t num_pages, @@ -1034,6 +1065,17 @@ int btrfs_release_file(struct inode * inode, struct file * filp) return 0; } +/* + * fsync call for both files and directories. This logs the inode into + * the tree log instead of forcing full commits whenever possible. + * + * It needs to call filemap_fdatawait so that all ordered extent updates are + * in the metadata btree are up to date for copying to the log. + * + * It drops the inode mutex before doing the tree log commit. This is an + * important optimization for directories because holding the mutex prevents + * new operations on the dir while we write to disk. + */ int btrfs_sync_file(struct file *file, struct dentry *dentry, int datasync) { struct inode *inode = dentry->d_inode; diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 404704d2682..f3abecc2d14 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -83,6 +83,10 @@ static unsigned char btrfs_type_by_mode[S_IFMT >> S_SHIFT] = { static void btrfs_truncate(struct inode *inode); +/* + * a very lame attempt at stopping writes when the FS is 85% full. There + * are countless ways this is incorrect, but it is better than nothing. + */ int btrfs_check_free_space(struct btrfs_root *root, u64 num_required, int for_del) { @@ -108,6 +112,12 @@ int btrfs_check_free_space(struct btrfs_root *root, u64 num_required, return ret; } +/* + * when extent_io.c finds a delayed allocation range in the file, + * the call backs end up in this code. The basic idea is to + * allocate extents on disk for the range, and create ordered data structs + * in ram to track those extents. + */ static int cow_file_range(struct inode *inode, u64 start, u64 end) { struct btrfs_root *root = BTRFS_I(inode)->root; @@ -185,6 +195,13 @@ out: return ret; } +/* + * when nowcow writeback call back. This checks for snapshots or COW copies + * of the extents that exist in the file, and COWs the file as required. + * + * If no cow copies or snapshots exist, we write directly to the existing + * blocks on disk + */ static int run_delalloc_nocow(struct inode *inode, u64 start, u64 end) { u64 extent_start; @@ -291,6 +308,9 @@ out: return err; } +/* + * extent_io.c call back to do delayed allocation processing + */ static int run_delalloc_range(struct inode *inode, u64 start, u64 end) { struct btrfs_root *root = BTRFS_I(inode)->root; @@ -305,6 +325,11 @@ static int run_delalloc_range(struct inode *inode, u64 start, u64 end) return ret; } +/* + * extent_io.c set_bit_hook, used to track delayed allocation + * bytes in this file, and to maintain the list of inodes that + * have pending delalloc work to be done. + */ int btrfs_set_bit_hook(struct inode *inode, u64 start, u64 end, unsigned long old, unsigned long bits) { @@ -323,6 +348,9 @@ int btrfs_set_bit_hook(struct inode *inode, u64 start, u64 end, return 0; } +/* + * extent_io.c clear_bit_hook, see set_bit_hook for why + */ int btrfs_clear_bit_hook(struct inode *inode, u64 start, u64 end, unsigned long old, unsigned long bits) { @@ -349,6 +377,10 @@ int btrfs_clear_bit_hook(struct inode *inode, u64 start, u64 end, return 0; } +/* + * extent_io.c merge_bio_hook, this must check the chunk tree to make sure + * we don't create bios that span stripes or chunks + */ int btrfs_merge_bio_hook(struct page *page, unsigned long offset, size_t size, struct bio *bio) { @@ -371,6 +403,14 @@ int btrfs_merge_bio_hook(struct page *page, unsigned long offset, return 0; } +/* + * in order to insert checksums into the metadata in large chunks, + * we wait until bio submission time. All the pages in the bio are + * checksummed and sums are attached onto the ordered extent record. + * + * At IO completion time the cums attached on the ordered extent record + * are inserted into the btree + */ int __btrfs_submit_bio_hook(struct inode *inode, int rw, struct bio *bio, int mirror_num) { @@ -383,6 +423,10 @@ int __btrfs_submit_bio_hook(struct inode *inode, int rw, struct bio *bio, return btrfs_map_bio(root, rw, bio, mirror_num, 1); } +/* + * extent_io.c submission hook. This does the right thing for csum calculation on write, + * or reading the csums from the tree before a read + */ int btrfs_submit_bio_hook(struct inode *inode, int rw, struct bio *bio, int mirror_num) { @@ -408,6 +452,10 @@ mapit: return btrfs_map_bio(root, rw, bio, mirror_num, 0); } +/* + * given a list of ordered sums record them in the inode. This happens + * at IO completion time based on sums calculated at bio submission time. + */ static noinline int add_pending_csums(struct btrfs_trans_handle *trans, struct inode *inode, u64 file_offset, struct list_head *list) @@ -430,12 +478,12 @@ int btrfs_set_extent_delalloc(struct inode *inode, u64 start, u64 end) GFP_NOFS); } +/* see btrfs_writepage_start_hook for details on why this is required */ struct btrfs_writepage_fixup { struct page *page; struct btrfs_work work; }; -/* see btrfs_writepage_start_hook for details on why this is required */ void btrfs_writepage_fixup_worker(struct btrfs_work *work) { struct btrfs_writepage_fixup *fixup; @@ -522,6 +570,10 @@ int btrfs_writepage_start_hook(struct page *page, u64 start, u64 end) return -EAGAIN; } +/* as ordered data IO finishes, this gets called so we can finish + * an ordered extent if the range of bytes in the file it covers are + * fully written. + */ static int btrfs_finish_ordered_io(struct inode *inode, u64 start, u64 end) { struct btrfs_root *root = BTRFS_I(inode)->root; @@ -631,6 +683,14 @@ int btrfs_writepage_end_io_hook(struct page *page, u64 start, u64 end, return btrfs_finish_ordered_io(page->mapping->host, start, end); } +/* + * When IO fails, either with EIO or csum verification fails, we + * try other mirrors that might have a good copy of the data. This + * io_failure_record is used to record state as we go through all the + * mirrors. If another mirror has good data, the page is set up to date + * and things continue. If a good mirror can't be found, the original + * bio end_io callback is called to indicate things have failed. + */ struct io_failure_record { struct page *page; u64 start; @@ -725,6 +785,10 @@ int btrfs_io_failed_hook(struct bio *failed_bio, return 0; } +/* + * each time an IO finishes, we do a fast check in the IO failure tree + * to see if we need to process or clean up an io_failure_record + */ int btrfs_clean_io_failures(struct inode *inode, u64 start) { u64 private; @@ -753,6 +817,11 @@ int btrfs_clean_io_failures(struct inode *inode, u64 start) return 0; } +/* + * when reads are done, we need to check csums to verify the data is correct + * if there's a match, we allow the bio to finish. If not, we go through + * the io_failure_record routines to find good copies + */ int btrfs_readpage_end_io_hook(struct page *page, u64 start, u64 end, struct extent_state *state) { @@ -990,6 +1059,9 @@ void btrfs_orphan_cleanup(struct btrfs_root *root) btrfs_free_path(path); } +/* + * read an inode from the btree into the in-memory inode + */ void btrfs_read_locked_inode(struct inode *inode) { struct btrfs_path *path; @@ -1083,6 +1155,9 @@ make_bad: make_bad_inode(inode); } +/* + * given a leaf and an inode, copy the inode fields into the leaf + */ static void fill_inode_item(struct btrfs_trans_handle *trans, struct extent_buffer *leaf, struct btrfs_inode_item *item, @@ -1118,6 +1193,9 @@ static void fill_inode_item(struct btrfs_trans_handle *trans, BTRFS_I(inode)->block_group->key.objectid); } +/* + * copy everything in the in-memory inode into the btree. + */ int noinline btrfs_update_inode(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct inode *inode) @@ -1151,6 +1229,11 @@ failed: } +/* + * unlink helper that gets used here in inode.c and in the tree logging + * recovery code. It remove a link in a directory with a given name, and + * also drops the back refs in the inode to the directory + */ int btrfs_unlink_inode(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct inode *dir, struct inode *inode, @@ -1309,7 +1392,7 @@ fail: /* * this can truncate away extent items, csum items and directory items. * It starts at a high offset and removes keys until it can't find - * any higher than i_size. + * any higher than new_size * * csum items that cross the new i_size are truncated to the new size * as well. @@ -2123,6 +2206,11 @@ void btrfs_dirty_inode(struct inode *inode) btrfs_end_transaction(trans, root); } +/* + * find the highest existing sequence number in a directory + * and then set the in-memory index_cnt variable to reflect + * free sequence numbers + */ static int btrfs_set_inode_index_count(struct inode *inode) { struct btrfs_root *root = BTRFS_I(inode)->root; @@ -2175,6 +2263,10 @@ out: return ret; } +/* + * helper to find a free sequence number in a given directory. This current + * code is very simple, later versions will do smarter things in the btree + */ static int btrfs_set_inode_index(struct inode *dir, struct inode *inode, u64 *index) { @@ -2305,6 +2397,12 @@ static inline u8 btrfs_inode_type(struct inode *inode) return btrfs_type_by_mode[(inode->i_mode & S_IFMT) >> S_SHIFT]; } +/* + * utility function to add 'inode' into 'parent_inode' with + * a give name and a given sequence number. + * if 'add_backref' is true, also insert a backref from the + * inode to the parent directory. + */ int btrfs_add_link(struct btrfs_trans_handle *trans, struct inode *parent_inode, struct inode *inode, const char *name, int name_len, int add_backref, u64 index) @@ -2611,6 +2709,10 @@ out_unlock: return err; } +/* helper for btfs_get_extent. Given an existing extent in the tree, + * and an extent that you want to insert, deal with overlap and insert + * the new extent into the tree. + */ static int merge_extent_mapping(struct extent_map_tree *em_tree, struct extent_map *existing, struct extent_map *em, @@ -2627,6 +2729,14 @@ static int merge_extent_mapping(struct extent_map_tree *em_tree, return add_extent_mapping(em_tree, em); } +/* + * a bit scary, this does extent mapping from logical file offset to the disk. + * the ugly parts come from merging extents from the disk with the + * in-ram representation. This gets more complex because of the data=ordered code, + * where the in-ram extents might be locked pending data=ordered completion. + * + * This also copies inline extents directly into the page. + */ struct extent_map *btrfs_get_extent(struct inode *inode, struct page *page, size_t pg_offset, u64 start, u64 len, int create) @@ -2869,76 +2979,11 @@ out: return em; } -#if 0 /* waiting for O_DIRECT reads */ -static int btrfs_get_block(struct inode *inode, sector_t iblock, - struct buffer_head *bh_result, int create) -{ - struct extent_map *em; - u64 start = (u64)iblock << inode->i_blkbits; - struct btrfs_multi_bio *multi = NULL; - struct btrfs_root *root = BTRFS_I(inode)->root; - u64 len; - u64 logical; - u64 map_length; - int ret = 0; - - em = btrfs_get_extent(inode, NULL, 0, start, bh_result->b_size, 0); - - if (!em || IS_ERR(em)) - goto out; - - if (em->start > start || em->start + em->len <= start) { - goto out; - } - - if (em->block_start == EXTENT_MAP_INLINE) { - ret = -EINVAL; - goto out; - } - - len = em->start + em->len - start; - len = min_t(u64, len, INT_LIMIT(typeof(bh_result->b_size))); - - if (em->block_start == EXTENT_MAP_HOLE || - em->block_start == EXTENT_MAP_DELALLOC) { - bh_result->b_size = len; - goto out; - } - - logical = start - em->start; - logical = em->block_start + logical; - - map_length = len; - ret = btrfs_map_block(&root->fs_info->mapping_tree, READ, - logical, &map_length, &multi, 0); - BUG_ON(ret); - bh_result->b_blocknr = multi->stripes[0].physical >> inode->i_blkbits; - bh_result->b_size = min(map_length, len); - - bh_result->b_bdev = multi->stripes[0].dev->bdev; - set_buffer_mapped(bh_result); - kfree(multi); -out: - free_extent_map(em); - return ret; -} -#endif - static ssize_t btrfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t offset, unsigned long nr_segs) { return -EINVAL; -#if 0 - struct file *file = iocb->ki_filp; - struct inode *inode = file->f_mapping->host; - - if (rw == WRITE) - return -EINVAL; - - return blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov, - offset, nr_segs, btrfs_get_block, NULL); -#endif } static sector_t btrfs_bmap(struct address_space *mapping, sector_t iblock) @@ -3202,6 +3247,9 @@ void btrfs_invalidate_dcache_root(struct btrfs_root *root, char *name, } } +/* + * create a new subvolume directory/inode (helper for the ioctl). + */ int btrfs_create_subvol_root(struct btrfs_root *new_root, struct btrfs_trans_handle *trans, u64 new_dirid, struct btrfs_block_group_cache *block_group) @@ -3223,6 +3271,9 @@ int btrfs_create_subvol_root(struct btrfs_root *new_root, return btrfs_update_inode(trans, new_root, inode); } +/* helper function for file defrag and space balancing. This + * forces readahead on a given range of bytes in an inode + */ unsigned long btrfs_force_ra(struct address_space *mapping, struct file_ra_state *ra, struct file *file, pgoff_t offset, pgoff_t last_index) @@ -3424,6 +3475,10 @@ out_unlock: return ret; } +/* + * some fairly slow code that needs optimization. This walks the list + * of all the inodes with pending delalloc and forces them to disk. + */ int btrfs_start_delalloc_inodes(struct btrfs_root *root) { struct list_head *head = &root->fs_info->delalloc_inodes; diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c index 0cc314c10d6..e30aa6e2958 100644 --- a/fs/btrfs/locking.c +++ b/fs/btrfs/locking.c @@ -25,6 +25,15 @@ #include "extent_io.h" #include "locking.h" +/* + * locks the per buffer mutex in an extent buffer. This uses adaptive locks + * and the spin is not tuned very extensively. The spinning does make a big + * difference in almost every workload, but spinning for the right amount of + * time needs some help. + * + * In general, we want to spin as long as the lock holder is doing btree searches, + * and we should give up if they are in more expensive code. + */ int btrfs_tree_lock(struct extent_buffer *eb) { int i; @@ -57,6 +66,10 @@ int btrfs_tree_locked(struct extent_buffer *eb) return mutex_is_locked(&eb->mutex); } +/* + * btrfs_search_slot uses this to decide if it should drop its locks + * before doing something expensive like allocating free blocks for cow. + */ int btrfs_path_lock_waiting(struct btrfs_path *path, int level) { int i; diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c index 951eacff242..dcc1730dd83 100644 --- a/fs/btrfs/ordered-data.c +++ b/fs/btrfs/ordered-data.c @@ -26,7 +26,6 @@ #include "btrfs_inode.h" #include "extent_io.h" - static u64 entry_end(struct btrfs_ordered_extent *entry) { if (entry->file_offset + entry->len < entry->file_offset) @@ -34,6 +33,9 @@ static u64 entry_end(struct btrfs_ordered_extent *entry) return entry->file_offset + entry->len; } +/* returns NULL if the insertion worked, or it returns the node it did find + * in the tree + */ static struct rb_node *tree_insert(struct rb_root *root, u64 file_offset, struct rb_node *node) { @@ -58,6 +60,10 @@ static struct rb_node *tree_insert(struct rb_root *root, u64 file_offset, return NULL; } +/* + * look for a given offset in the tree, and if it can't be found return the + * first lesser offset + */ static struct rb_node *__tree_search(struct rb_root *root, u64 file_offset, struct rb_node **prev_ret) { @@ -108,6 +114,9 @@ static struct rb_node *__tree_search(struct rb_root *root, u64 file_offset, return NULL; } +/* + * helper to check if a given offset is inside a given entry + */ static int offset_in_entry(struct btrfs_ordered_extent *entry, u64 file_offset) { if (file_offset < entry->file_offset || @@ -116,6 +125,10 @@ static int offset_in_entry(struct btrfs_ordered_extent *entry, u64 file_offset) return 1; } +/* + * look find the first ordered struct that has this offset, otherwise + * the first one less than this offset + */ static inline struct rb_node *tree_search(struct btrfs_ordered_inode_tree *tree, u64 file_offset) { @@ -305,6 +318,10 @@ int btrfs_remove_ordered_extent(struct inode *inode, return 0; } +/* + * wait for all the ordered extents in a root. This is done when balancing + * space between drives. + */ int btrfs_wait_ordered_extents(struct btrfs_root *root, int nocow_only) { struct list_head splice; diff --git a/fs/btrfs/ref-cache.c b/fs/btrfs/ref-cache.c index 30fcb7aea5b..a50ebb67055 100644 --- a/fs/btrfs/ref-cache.c +++ b/fs/btrfs/ref-cache.c @@ -21,6 +21,16 @@ #include "ref-cache.h" #include "transaction.h" +/* + * leaf refs are used to cache the information about which extents + * a given leaf has references on. This allows us to process that leaf + * in btrfs_drop_snapshot without needing to read it back from disk. + */ + +/* + * kmalloc a leaf reference struct and update the counters for the + * total ref cache size + */ struct btrfs_leaf_ref *btrfs_alloc_leaf_ref(struct btrfs_root *root, int nr_extents) { @@ -40,6 +50,10 @@ struct btrfs_leaf_ref *btrfs_alloc_leaf_ref(struct btrfs_root *root, return ref; } +/* + * free a leaf reference struct and update the counters for the + * total ref cache size + */ void btrfs_free_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref) { if (!ref) @@ -135,6 +149,10 @@ int btrfs_remove_leaf_refs(struct btrfs_root *root, u64 max_root_gen, return 0; } +/* + * find the leaf ref for a given extent. This returns the ref struct with + * a usage reference incremented + */ struct btrfs_leaf_ref *btrfs_lookup_leaf_ref(struct btrfs_root *root, u64 bytenr) { @@ -160,6 +178,10 @@ again: return NULL; } +/* + * add a fully filled in leaf ref struct + * remove all the refs older than a given root generation + */ int btrfs_add_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref, int shared) { @@ -184,6 +206,10 @@ int btrfs_add_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref, return ret; } +/* + * remove a single leaf ref from the tree. This drops the ref held by the tree + * only + */ int btrfs_remove_leaf_ref(struct btrfs_root *root, struct btrfs_leaf_ref *ref) { struct btrfs_leaf_ref_tree *tree; diff --git a/fs/btrfs/ref-cache.h b/fs/btrfs/ref-cache.h index 617564787f5..16f3183d7c5 100644 --- a/fs/btrfs/ref-cache.h +++ b/fs/btrfs/ref-cache.h @@ -19,8 +19,11 @@ #define __REFCACHE__ struct btrfs_extent_info { + /* bytenr and num_bytes find the extent in the extent allocation tree */ u64 bytenr; u64 num_bytes; + + /* objectid and offset find the back reference for the file */ u64 objectid; u64 offset; }; diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c index 0091c01abb0..eb7f7655e9d 100644 --- a/fs/btrfs/root-tree.c +++ b/fs/btrfs/root-tree.c @@ -22,8 +22,10 @@ #include "print-tree.h" /* - * returns 0 on finding something, 1 if no more roots are there - * and < 0 on error + * search forward for a root, starting with objectid 'search_start' + * if a root key is found, the objectid we find is filled into 'found_objectid' + * and 0 is returned. < 0 is returned on error, 1 if there is nothing + * left in the tree. */ int btrfs_search_root(struct btrfs_root *root, u64 search_start, u64 *found_objectid) @@ -66,6 +68,11 @@ out: return ret; } +/* + * lookup the root with the highest offset for a given objectid. The key we do + * find is copied into 'key'. If we find something return 0, otherwise 1, < 0 + * on error. + */ int btrfs_find_last_root(struct btrfs_root *root, u64 objectid, struct btrfs_root_item *item, struct btrfs_key *key) { @@ -104,6 +111,9 @@ out: return ret; } +/* + * copy the data in 'item' into the btree + */ int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_key *key, struct btrfs_root_item *item) @@ -147,6 +157,12 @@ int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root return ret; } +/* + * at mount time we want to find all the old transaction snapshots that were in + * the process of being deleted if we crashed. This is any root item with an offset + * lower than the latest root. They need to be queued for deletion to finish + * what was happening when we crashed. + */ int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid, struct btrfs_root *latest) { @@ -227,6 +243,7 @@ err: return ret; } +/* drop the root item for 'key' from 'root' */ int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root, struct btrfs_key *key) { diff --git a/fs/btrfs/struct-funcs.c b/fs/btrfs/struct-funcs.c index ad03a32d111..cdedbe144d4 100644 --- a/fs/btrfs/struct-funcs.c +++ b/fs/btrfs/struct-funcs.c @@ -17,6 +17,27 @@ */ #include + +/* this is some deeply nasty code. ctree.h has a different + * definition for this BTRFS_SETGET_FUNCS macro, behind a #ifndef + * + * The end result is that anyone who #includes ctree.h gets a + * declaration for the btrfs_set_foo functions and btrfs_foo functions + * + * This file declares the macros and then #includes ctree.h, which results + * in cpp creating the function here based on the template below. + * + * These setget functions do all the extent_buffer related mapping + * required to efficiently read and write specific fields in the extent + * buffers. Every pointer to metadata items in btrfs is really just + * an unsigned long offset into the extent buffer which has been + * cast to a specific type. This gives us all the gcc type checking. + * + * The extent buffer api is used to do all the kmapping and page + * spanning work required to get extent buffers in highmem and have + * a metadata blocksize different from the page size. + */ + #define BTRFS_SETGET_FUNCS(name, type, member, bits) \ u##bits btrfs_##name(struct extent_buffer *eb, \ type *s) \ diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 8399d6d05d6..2e6039825b7 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -519,6 +519,9 @@ static struct file_system_type btrfs_fs_type = { .fs_flags = FS_REQUIRES_DEV, }; +/* + * used by btrfsctl to scan devices when no FS is mounted + */ static long btrfs_control_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 444abe0796a..11266d68a6c 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -46,6 +46,9 @@ static noinline void put_transaction(struct btrfs_transaction *transaction) } } +/* + * either allocate a new transaction or hop into the existing one + */ static noinline int join_transaction(struct btrfs_root *root) { struct btrfs_transaction *cur_trans; @@ -85,6 +88,12 @@ static noinline int join_transaction(struct btrfs_root *root) return 0; } +/* + * this does all the record keeping required to make sure that a + * reference counted root is properly recorded in a given transaction. + * This is required to make sure the old root from before we joined the transaction + * is deleted when the transaction commits + */ noinline int btrfs_record_root_in_trans(struct btrfs_root *root) { struct btrfs_dirty_root *dirty; @@ -127,6 +136,10 @@ noinline int btrfs_record_root_in_trans(struct btrfs_root *root) return 0; } +/* wait for commit against the current transaction to become unblocked + * when this is done, it is safe to start a new transaction, but the current + * transaction might not be fully on disk. + */ static void wait_current_trans(struct btrfs_root *root) { struct btrfs_transaction *cur_trans; @@ -198,7 +211,7 @@ struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *r, return start_transaction(r, num_blocks, 2); } - +/* wait for a transaction commit to be fully complete */ static noinline int wait_for_commit(struct btrfs_root *root, struct btrfs_transaction *commit) { @@ -218,6 +231,10 @@ static noinline int wait_for_commit(struct btrfs_root *root, return 0; } +/* + * rate limit against the drop_snapshot code. This helps to slow down new operations + * if the drop_snapshot code isn't able to keep up. + */ static void throttle_on_drops(struct btrfs_root *root) { struct btrfs_fs_info *info = root->fs_info; @@ -302,7 +319,11 @@ int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans, return __btrfs_end_transaction(trans, root, 1); } - +/* + * when btree blocks are allocated, they have some corresponding bits set for + * them in one of two extent_io trees. This is used to make sure all of + * those extents are on disk for transaction or log commit + */ int btrfs_write_and_wait_marked_extents(struct btrfs_root *root, struct extent_io_tree *dirty_pages) { @@ -393,6 +414,16 @@ int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans, &trans->transaction->dirty_pages); } +/* + * this is used to update the root pointer in the tree of tree roots. + * + * But, in the case of the extent allocation tree, updating the root + * pointer may allocate blocks which may change the root of the extent + * allocation tree. + * + * So, this loops and repeats and makes sure the cowonly root didn't + * change while the root pointer was being updated in the metadata. + */ static int update_cowonly_root(struct btrfs_trans_handle *trans, struct btrfs_root *root) { @@ -418,6 +449,9 @@ static int update_cowonly_root(struct btrfs_trans_handle *trans, return 0; } +/* + * update all the cowonly tree roots on disk + */ int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans, struct btrfs_root *root) { @@ -433,6 +467,11 @@ int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans, return 0; } +/* + * dead roots are old snapshots that need to be deleted. This allocates + * a dirty root struct and adds it into the list of dead roots that need to + * be deleted + */ int btrfs_add_dead_root(struct btrfs_root *root, struct btrfs_root *latest) { struct btrfs_dirty_root *dirty; @@ -449,6 +488,12 @@ int btrfs_add_dead_root(struct btrfs_root *root, struct btrfs_root *latest) return 0; } +/* + * at transaction commit time we need to schedule the old roots for + * deletion via btrfs_drop_snapshot. This runs through all the + * reference counted roots that were modified in the current + * transaction and puts them into the drop list + */ static noinline int add_dirty_roots(struct btrfs_trans_handle *trans, struct radix_tree_root *radix, struct list_head *list) @@ -541,6 +586,10 @@ static noinline int add_dirty_roots(struct btrfs_trans_handle *trans, return err; } +/* + * defrag a given btree. If cacheonly == 1, this won't read from the disk, + * otherwise every leaf in the btree is read and defragged. + */ int btrfs_defrag_root(struct btrfs_root *root, int cacheonly) { struct btrfs_fs_info *info = root->fs_info; @@ -570,6 +619,10 @@ int btrfs_defrag_root(struct btrfs_root *root, int cacheonly) return 0; } +/* + * Given a list of roots that need to be deleted, call btrfs_drop_snapshot on + * all of them + */ static noinline int drop_dirty_roots(struct btrfs_root *tree_root, struct list_head *list) { @@ -664,6 +717,10 @@ static noinline int drop_dirty_roots(struct btrfs_root *tree_root, return ret; } +/* + * new snapshots need to be created at a very specific time in the + * transaction commit. This does the actual creation + */ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans, struct btrfs_fs_info *fs_info, struct btrfs_pending_snapshot *pending) @@ -734,6 +791,9 @@ fail: return ret; } +/* + * create all the snapshots we've scheduled for creation + */ static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans, struct btrfs_fs_info *fs_info) { @@ -944,6 +1004,9 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans, return ret; } +/* + * interface function to delete all the snapshots we have scheduled for deletion + */ int btrfs_clean_old_snapshots(struct btrfs_root *root) { struct list_head dirty_roots; diff --git a/fs/btrfs/tree-defrag.c b/fs/btrfs/tree-defrag.c index b3bb5bbad76..6f57d0889b1 100644 --- a/fs/btrfs/tree-defrag.c +++ b/fs/btrfs/tree-defrag.c @@ -23,6 +23,10 @@ #include "transaction.h" #include "locking.h" +/* defrag all the leaves in a given btree. If cache_only == 1, don't read things + * from disk, otherwise read all the leaves and try to get key order to + * better reflect disk order + */ int btrfs_defrag_leaves(struct btrfs_trans_handle *trans, struct btrfs_root *root, int cache_only) { -- cgit v1.2.3-70-g09d2 From 4a69a41009c4ac691f7d9c289f5f37fabeddce46 Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Thu, 6 Nov 2008 22:03:00 -0500 Subject: Btrfs: Add ordered async work queues Btrfs uses kernel threads to create async work queues for cpu intensive operations such as checksumming and decompression. These work well, but they make it difficult to keep IO order intact. A single writepages call from pdflush or fsync will turn into a number of bios, and each bio is checksummed in parallel. Once the checksum is computed, the bio is sent down to the disk, and since we don't control the order in which the parallel operations happen, they might go down to the disk in almost any order. The code deals with this somewhat by having deep work queues for a single kernel thread, making it very likely that a single thread will process all the bios for a single inode. This patch introduces an explicitly ordered work queue. As work structs are placed into the queue they are put onto the tail of a list. They have three callbacks: ->func (cpu intensive processing here) ->ordered_func (order sensitive processing here) ->ordered_free (free the work struct, all processing is done) The work struct has three callbacks. The func callback does the cpu intensive work, and when it completes the work struct is marked as done. Every time a work struct completes, the list is checked to see if the head is marked as done. If so the ordered_func callback is used to do the order sensitive processing and the ordered_free callback is used to do any cleanup. Then we loop back and check the head of the list again. This patch also changes the checksumming code to use the ordered workqueues. One a 4 drive array, it increases streaming writes from 280MB/s to 350MB/s. Signed-off-by: Chris Mason --- fs/btrfs/async-thread.c | 67 ++++++++++++++++++++++++++++++++++++++-- fs/btrfs/async-thread.h | 18 ++++++++++- fs/btrfs/disk-io.c | 81 ++++++++++++++++++++++++++++++++++--------------- fs/btrfs/disk-io.h | 4 ++- fs/btrfs/inode.c | 19 ++++++++++-- 5 files changed, 158 insertions(+), 31 deletions(-) (limited to 'fs/btrfs/async-thread.h') diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c index d82efd722a4..e1e49715459 100644 --- a/fs/btrfs/async-thread.c +++ b/fs/btrfs/async-thread.c @@ -23,6 +23,10 @@ # include #include "async-thread.h" +#define WORK_QUEUED_BIT 0 +#define WORK_DONE_BIT 1 +#define WORK_ORDER_DONE_BIT 2 + /* * container for the kthread task pointer and the list of pending work * One of these is allocated per thread. @@ -88,6 +92,47 @@ static void check_busy_worker(struct btrfs_worker_thread *worker) } } +static noinline int run_ordered_completions(struct btrfs_workers *workers, + struct btrfs_work *work) +{ + unsigned long flags; + + if (!workers->ordered) + return 0; + + set_bit(WORK_DONE_BIT, &work->flags); + + spin_lock_irqsave(&workers->lock, flags); + + while(!list_empty(&workers->order_list)) { + work = list_entry(workers->order_list.next, + struct btrfs_work, order_list); + + if (!test_bit(WORK_DONE_BIT, &work->flags)) + break; + + /* we are going to call the ordered done function, but + * we leave the work item on the list as a barrier so + * that later work items that are done don't have their + * functions called before this one returns + */ + if (test_and_set_bit(WORK_ORDER_DONE_BIT, &work->flags)) + break; + + spin_unlock_irqrestore(&workers->lock, flags); + + work->ordered_func(work); + + /* now take the lock again and call the freeing code */ + spin_lock_irqsave(&workers->lock, flags); + list_del(&work->order_list); + work->ordered_free(work); + } + + spin_unlock_irqrestore(&workers->lock, flags); + return 0; +} + /* * main loop for servicing work items */ @@ -102,7 +147,7 @@ static int worker_loop(void *arg) cur = worker->pending.next; work = list_entry(cur, struct btrfs_work, list); list_del(&work->list); - clear_bit(0, &work->flags); + clear_bit(WORK_QUEUED_BIT, &work->flags); work->worker = worker; spin_unlock_irq(&worker->lock); @@ -110,8 +155,15 @@ static int worker_loop(void *arg) work->func(work); atomic_dec(&worker->num_pending); + /* + * unless this is an ordered work queue, + * 'work' was probably freed by func above. + */ + run_ordered_completions(worker->workers, work); + spin_lock_irq(&worker->lock); check_idle_worker(worker); + } worker->working = 0; if (freezing(current)) { @@ -154,10 +206,12 @@ void btrfs_init_workers(struct btrfs_workers *workers, char *name, int max) workers->num_workers = 0; INIT_LIST_HEAD(&workers->worker_list); INIT_LIST_HEAD(&workers->idle_list); + INIT_LIST_HEAD(&workers->order_list); spin_lock_init(&workers->lock); workers->max_workers = max; workers->idle_thresh = 32; workers->name = name; + workers->ordered = 0; } /* @@ -296,7 +350,7 @@ int btrfs_requeue_work(struct btrfs_work *work) struct btrfs_worker_thread *worker = work->worker; unsigned long flags; - if (test_and_set_bit(0, &work->flags)) + if (test_and_set_bit(WORK_QUEUED_BIT, &work->flags)) goto out; spin_lock_irqsave(&worker->lock, flags); @@ -330,10 +384,17 @@ int btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work) int wake = 0; /* don't requeue something already on a list */ - if (test_and_set_bit(0, &work->flags)) + if (test_and_set_bit(WORK_QUEUED_BIT, &work->flags)) goto out; worker = find_worker(workers); + if (workers->ordered) { + spin_lock_irqsave(&workers->lock, flags); + list_add_tail(&work->order_list, &workers->order_list); + spin_unlock_irqrestore(&workers->lock, flags); + } else { + INIT_LIST_HEAD(&work->order_list); + } spin_lock_irqsave(&worker->lock, flags); atomic_inc(&worker->num_pending); diff --git a/fs/btrfs/async-thread.h b/fs/btrfs/async-thread.h index 4ec9a2ee0f9..31be4ed8b63 100644 --- a/fs/btrfs/async-thread.h +++ b/fs/btrfs/async-thread.h @@ -37,10 +37,16 @@ struct btrfs_worker_thread; */ struct btrfs_work { /* - * only func should be set to the function you want called + * func should be set to the function you want called * your work struct is passed as the only arg + * + * ordered_func must be set for work sent to an ordered work queue, + * and it is called to complete a given work item in the same + * order they were sent to the queue. */ void (*func)(struct btrfs_work *work); + void (*ordered_func)(struct btrfs_work *work); + void (*ordered_free)(struct btrfs_work *work); /* * flags should be set to zero. It is used to make sure the @@ -51,6 +57,7 @@ struct btrfs_work { /* don't touch these */ struct btrfs_worker_thread *worker; struct list_head list; + struct list_head order_list; }; struct btrfs_workers { @@ -63,6 +70,9 @@ struct btrfs_workers { /* once a worker has this many requests or fewer, it is idle */ int idle_thresh; + /* force completions in the order they were queued */ + int ordered; + /* list with all the work threads. The workers on the idle thread * may be actively servicing jobs, but they haven't yet hit the * idle thresh limit above. @@ -70,6 +80,12 @@ struct btrfs_workers { struct list_head worker_list; struct list_head idle_list; + /* + * when operating in ordered mode, this maintains the list + * of work items waiting for completion + */ + struct list_head order_list; + /* lock for finding the next worker thread to queue on */ spinlock_t lock; diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 94b4e50f6b2..e0a28f705a6 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -80,7 +80,8 @@ struct async_submit_bio { struct inode *inode; struct bio *bio; struct list_head list; - extent_submit_bio_hook_t *submit_bio_hook; + extent_submit_bio_hook_t *submit_bio_start; + extent_submit_bio_hook_t *submit_bio_done; int rw; int mirror_num; unsigned long bio_flags; @@ -452,7 +453,18 @@ int btrfs_congested_async(struct btrfs_fs_info *info, int iodone) btrfs_async_submit_limit(info); } -static void run_one_async_submit(struct btrfs_work *work) +static void run_one_async_start(struct btrfs_work *work) +{ + struct btrfs_fs_info *fs_info; + struct async_submit_bio *async; + + async = container_of(work, struct async_submit_bio, work); + fs_info = BTRFS_I(async->inode)->root->fs_info; + async->submit_bio_start(async->inode, async->rw, async->bio, + async->mirror_num, async->bio_flags); +} + +static void run_one_async_done(struct btrfs_work *work) { struct btrfs_fs_info *fs_info; struct async_submit_bio *async; @@ -470,15 +482,23 @@ static void run_one_async_submit(struct btrfs_work *work) waitqueue_active(&fs_info->async_submit_wait)) wake_up(&fs_info->async_submit_wait); - async->submit_bio_hook(async->inode, async->rw, async->bio, + async->submit_bio_done(async->inode, async->rw, async->bio, async->mirror_num, async->bio_flags); +} + +static void run_one_async_free(struct btrfs_work *work) +{ + struct async_submit_bio *async; + + async = container_of(work, struct async_submit_bio, work); kfree(async); } int btrfs_wq_submit_bio(struct btrfs_fs_info *fs_info, struct inode *inode, int rw, struct bio *bio, int mirror_num, unsigned long bio_flags, - extent_submit_bio_hook_t *submit_bio_hook) + extent_submit_bio_hook_t *submit_bio_start, + extent_submit_bio_hook_t *submit_bio_done) { struct async_submit_bio *async; int limit = btrfs_async_submit_limit(fs_info); @@ -491,8 +511,13 @@ int btrfs_wq_submit_bio(struct btrfs_fs_info *fs_info, struct inode *inode, async->rw = rw; async->bio = bio; async->mirror_num = mirror_num; - async->submit_bio_hook = submit_bio_hook; - async->work.func = run_one_async_submit; + async->submit_bio_start = submit_bio_start; + async->submit_bio_done = submit_bio_done; + + async->work.func = run_one_async_start; + async->work.ordered_func = run_one_async_done; + async->work.ordered_free = run_one_async_free; + async->work.flags = 0; async->bio_flags = bio_flags; @@ -533,29 +558,25 @@ static int btree_csum_one_bio(struct bio *bio) return 0; } -static int __btree_submit_bio_hook(struct inode *inode, int rw, struct bio *bio, - int mirror_num, unsigned long bio_flags) +static int __btree_submit_bio_start(struct inode *inode, int rw, + struct bio *bio, int mirror_num, + unsigned long bio_flags) { - struct btrfs_root *root = BTRFS_I(inode)->root; - int ret; - /* * when we're called for a write, we're already in the async * submission context. Just jump into btrfs_map_bio */ - if (rw & (1 << BIO_RW)) { - btree_csum_one_bio(bio); - return btrfs_map_bio(BTRFS_I(inode)->root, rw, bio, - mirror_num, 1); - } + btree_csum_one_bio(bio); + return 0; +} +static int __btree_submit_bio_done(struct inode *inode, int rw, struct bio *bio, + int mirror_num, unsigned long bio_flags) +{ /* - * called for a read, do the setup so that checksum validation - * can happen in the async kernel threads + * when we're called for a write, we're already in the async + * submission context. Just jump into btrfs_map_bio */ - ret = btrfs_bio_wq_end_io(root->fs_info, bio, 1); - BUG_ON(ret); - return btrfs_map_bio(BTRFS_I(inode)->root, rw, bio, mirror_num, 1); } @@ -567,11 +588,22 @@ static int btree_submit_bio_hook(struct inode *inode, int rw, struct bio *bio, * can happen in parallel across all CPUs */ if (!(rw & (1 << BIO_RW))) { - return __btree_submit_bio_hook(inode, rw, bio, mirror_num, 0); + int ret; + /* + * called for a read, do the setup so that checksum validation + * can happen in the async kernel threads + */ + ret = btrfs_bio_wq_end_io(BTRFS_I(inode)->root->fs_info, + bio, 1); + BUG_ON(ret); + + return btrfs_map_bio(BTRFS_I(inode)->root, rw, bio, + mirror_num, 1); } return btrfs_wq_submit_bio(BTRFS_I(inode)->root->fs_info, inode, rw, bio, mirror_num, 0, - __btree_submit_bio_hook); + __btree_submit_bio_start, + __btree_submit_bio_done); } static int btree_writepage(struct page *page, struct writeback_control *wbc) @@ -1534,7 +1566,8 @@ struct btrfs_root *open_ctree(struct super_block *sb, * were sent by the writeback daemons, improving overall locality * of the IO going down the pipe. */ - fs_info->workers.idle_thresh = 128; + fs_info->workers.idle_thresh = 8; + fs_info->workers.ordered = 1; btrfs_init_workers(&fs_info->fixup_workers, "fixup", 1); btrfs_init_workers(&fs_info->endio_workers, "endio", diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h index 4eb1f1408d2..b8d5948fa27 100644 --- a/fs/btrfs/disk-io.h +++ b/fs/btrfs/disk-io.h @@ -72,7 +72,9 @@ int btrfs_bio_wq_end_io(struct btrfs_fs_info *info, struct bio *bio, int btrfs_wq_submit_bio(struct btrfs_fs_info *fs_info, struct inode *inode, int rw, struct bio *bio, int mirror_num, unsigned long bio_flags, - extent_submit_bio_hook_t *submit_bio_hook); + extent_submit_bio_hook_t *submit_bio_start, + extent_submit_bio_hook_t *submit_bio_done); + int btrfs_congested_async(struct btrfs_fs_info *info, int iodone); unsigned long btrfs_async_submit_limit(struct btrfs_fs_info *info); int btrfs_write_tree_block(struct extent_buffer *buf); diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 806708dd7e3..3df0ffad976 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -881,7 +881,7 @@ int btrfs_merge_bio_hook(struct page *page, unsigned long offset, * At IO completion time the cums attached on the ordered extent record * are inserted into the btree */ -int __btrfs_submit_bio_hook(struct inode *inode, int rw, struct bio *bio, +int __btrfs_submit_bio_start(struct inode *inode, int rw, struct bio *bio, int mirror_num, unsigned long bio_flags) { struct btrfs_root *root = BTRFS_I(inode)->root; @@ -889,7 +889,21 @@ int __btrfs_submit_bio_hook(struct inode *inode, int rw, struct bio *bio, ret = btrfs_csum_one_bio(root, inode, bio); BUG_ON(ret); + return 0; +} +/* + * in order to insert checksums into the metadata in large chunks, + * we wait until bio submission time. All the pages in the bio are + * checksummed and sums are attached onto the ordered extent record. + * + * At IO completion time the cums attached on the ordered extent record + * are inserted into the btree + */ +int __btrfs_submit_bio_done(struct inode *inode, int rw, struct bio *bio, + int mirror_num, unsigned long bio_flags) +{ + struct btrfs_root *root = BTRFS_I(inode)->root; return btrfs_map_bio(root, rw, bio, mirror_num, 1); } @@ -922,7 +936,8 @@ int btrfs_submit_bio_hook(struct inode *inode, int rw, struct bio *bio, /* we're doing a write, do the async checksumming */ return btrfs_wq_submit_bio(BTRFS_I(inode)->root->fs_info, inode, rw, bio, mirror_num, - bio_flags, __btrfs_submit_bio_hook); + bio_flags, __btrfs_submit_bio_start, + __btrfs_submit_bio_done); } mapit: -- cgit v1.2.3-70-g09d2