From ffbd517d5a8c8e93ddd11046434fb029f3df73aa Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Mon, 20 Apr 2009 15:50:09 -0400 Subject: Btrfs: use WRITE_SYNC for synchronous writes Part of reducing fsync/O_SYNC/O_DIRECT latencies is using WRITE_SYNC for writes we plan on waiting on in the near future. This patch mirrors recent changes in other filesystems and the generic code to use WRITE_SYNC when WB_SYNC_ALL is passed and to use WRITE_SYNC for other latency critical writes. Btrfs uses async worker threads for checksumming before the write is done, and then again to actually submit the bios. The bio submission code just runs a per-device list of bios that need to be sent down the pipe. This list is split into low priority and high priority lists so the WRITE_SYNC IO happens first. Signed-off-by: Chris Mason diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 92caa80..fec18b4 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2095,10 +2095,10 @@ static int write_dev_supers(struct btrfs_device *device, device->barriers = 0; get_bh(bh); lock_buffer(bh); - ret = submit_bh(WRITE, bh); + ret = submit_bh(WRITE_SYNC, bh); } } else { - ret = submit_bh(WRITE, bh); + ret = submit_bh(WRITE_SYNC, bh); } if (!ret && wait) { diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index eb2bee8..483b672 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -50,7 +50,10 @@ struct extent_page_data { /* tells writepage not to lock the state bits for this range * it still does the unlocking */ - int extent_locked; + unsigned int extent_locked:1; + + /* tells the submit_bio code to use a WRITE_SYNC */ + unsigned int sync_io:1; }; int __init extent_io_init(void) @@ -2136,8 +2139,14 @@ static int __extent_writepage(struct page *page, struct writeback_control *wbc, u64 delalloc_end; int page_started; int compressed; + int write_flags; unsigned long nr_written = 0; + if (wbc->sync_mode == WB_SYNC_ALL) + write_flags = WRITE_SYNC_PLUG; + else + write_flags = WRITE; + WARN_ON(!PageLocked(page)); pg_offset = i_size & (PAGE_CACHE_SIZE - 1); if (page->index > end_index || @@ -2314,9 +2323,9 @@ static int __extent_writepage(struct page *page, struct writeback_control *wbc, (unsigned long long)end); } - ret = submit_extent_page(WRITE, tree, page, sector, - iosize, pg_offset, bdev, - &epd->bio, max_nr, + ret = submit_extent_page(write_flags, tree, page, + sector, iosize, pg_offset, + bdev, &epd->bio, max_nr, end_bio_extent_writepage, 0, 0, 0); if (ret) @@ -2460,15 +2469,23 @@ retry: return ret; } -static noinline void flush_write_bio(void *data) +static void flush_epd_write_bio(struct extent_page_data *epd) { - struct extent_page_data *epd = data; if (epd->bio) { - submit_one_bio(WRITE, epd->bio, 0, 0); + if (epd->sync_io) + submit_one_bio(WRITE_SYNC, epd->bio, 0, 0); + else + submit_one_bio(WRITE, epd->bio, 0, 0); epd->bio = NULL; } } +static noinline void flush_write_bio(void *data) +{ + struct extent_page_data *epd = data; + flush_epd_write_bio(epd); +} + int extent_write_full_page(struct extent_io_tree *tree, struct page *page, get_extent_t *get_extent, struct writeback_control *wbc) @@ -2480,6 +2497,7 @@ int extent_write_full_page(struct extent_io_tree *tree, struct page *page, .tree = tree, .get_extent = get_extent, .extent_locked = 0, + .sync_io = wbc->sync_mode == WB_SYNC_ALL, }; struct writeback_control wbc_writepages = { .bdi = wbc->bdi, @@ -2490,13 +2508,11 @@ int extent_write_full_page(struct extent_io_tree *tree, struct page *page, .range_end = (loff_t)-1, }; - ret = __extent_writepage(page, wbc, &epd); extent_write_cache_pages(tree, mapping, &wbc_writepages, __extent_writepage, &epd, flush_write_bio); - if (epd.bio) - submit_one_bio(WRITE, epd.bio, 0, 0); + flush_epd_write_bio(&epd); return ret; } @@ -2515,6 +2531,7 @@ int extent_write_locked_range(struct extent_io_tree *tree, struct inode *inode, .tree = tree, .get_extent = get_extent, .extent_locked = 1, + .sync_io = mode == WB_SYNC_ALL, }; struct writeback_control wbc_writepages = { .bdi = inode->i_mapping->backing_dev_info, @@ -2540,8 +2557,7 @@ int extent_write_locked_range(struct extent_io_tree *tree, struct inode *inode, start += PAGE_CACHE_SIZE; } - if (epd.bio) - submit_one_bio(WRITE, epd.bio, 0, 0); + flush_epd_write_bio(&epd); return ret; } @@ -2556,13 +2572,13 @@ int extent_writepages(struct extent_io_tree *tree, .tree = tree, .get_extent = get_extent, .extent_locked = 0, + .sync_io = wbc->sync_mode == WB_SYNC_ALL, }; ret = extent_write_cache_pages(tree, mapping, wbc, __extent_writepage, &epd, flush_write_bio); - if (epd.bio) - submit_one_bio(WRITE, epd.bio, 0, 0); + flush_epd_write_bio(&epd); return ret; } diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c index 53c87b1..d6f0806 100644 --- a/fs/btrfs/ordered-data.c +++ b/fs/btrfs/ordered-data.c @@ -489,7 +489,7 @@ again: /* start IO across the range first to instantiate any delalloc * extents */ - btrfs_fdatawrite_range(inode->i_mapping, start, orig_end, WB_SYNC_NONE); + btrfs_fdatawrite_range(inode->i_mapping, start, orig_end, WB_SYNC_ALL); /* The compression code will leave pages locked but return from * writepage without setting the page writeback. Starting again diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index e0913e4..e53835b 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -125,6 +125,20 @@ static noinline struct btrfs_fs_devices *find_fsid(u8 *fsid) return NULL; } +static void requeue_list(struct btrfs_pending_bios *pending_bios, + struct bio *head, struct bio *tail) +{ + + struct bio *old_head; + + old_head = pending_bios->head; + pending_bios->head = head; + if (pending_bios->tail) + tail->bi_next = old_head; + else + pending_bios->tail = tail; +} + /* * we try to collect pending bios for a device so we don't get a large * number of procs sending bios down to the same device. This greatly @@ -141,10 +155,12 @@ static noinline int run_scheduled_bios(struct btrfs_device *device) struct bio *pending; struct backing_dev_info *bdi; struct btrfs_fs_info *fs_info; + struct btrfs_pending_bios *pending_bios; struct bio *tail; struct bio *cur; int again = 0; - unsigned long num_run = 0; + unsigned long num_run; + unsigned long num_sync_run; unsigned long limit; unsigned long last_waited = 0; @@ -153,20 +169,30 @@ static noinline int run_scheduled_bios(struct btrfs_device *device) limit = btrfs_async_submit_limit(fs_info); limit = limit * 2 / 3; + /* we want to make sure that every time we switch from the sync + * list to the normal list, we unplug + */ + num_sync_run = 0; + loop: spin_lock(&device->io_lock); + num_run = 0; loop_lock: + /* take all the bios off the list at once and process them * later on (without the lock held). But, remember the * tail and other pointers so the bios can be properly reinserted * into the list if we hit congestion */ - pending = device->pending_bios; - tail = device->pending_bio_tail; + if (device->pending_sync_bios.head) + pending_bios = &device->pending_sync_bios; + else + pending_bios = &device->pending_bios; + + pending = pending_bios->head; + tail = pending_bios->tail; WARN_ON(pending && !tail); - device->pending_bios = NULL; - device->pending_bio_tail = NULL; /* * if pending was null this time around, no bios need processing @@ -176,16 +202,41 @@ loop_lock: * device->running_pending is used to synchronize with the * schedule_bio code. */ - if (pending) { - again = 1; - device->running_pending = 1; - } else { + if (device->pending_sync_bios.head == NULL && + device->pending_bios.head == NULL) { again = 0; device->running_pending = 0; + } else { + again = 1; + device->running_pending = 1; } + + pending_bios->head = NULL; + pending_bios->tail = NULL; + spin_unlock(&device->io_lock); + /* + * if we're doing the regular priority list, make sure we unplug + * for any high prio bios we've sent down + */ + if (pending_bios == &device->pending_bios && num_sync_run > 0) { + num_sync_run = 0; + blk_run_backing_dev(bdi, NULL); + } + while (pending) { + + rmb(); + if (pending_bios != &device->pending_sync_bios && + device->pending_sync_bios.head && + num_run > 16) { + cond_resched(); + spin_lock(&device->io_lock); + requeue_list(pending_bios, pending, tail); + goto loop_lock; + } + cur = pending; pending = pending->bi_next; cur->bi_next = NULL; @@ -196,10 +247,18 @@ loop_lock: wake_up(&fs_info->async_submit_wait); BUG_ON(atomic_read(&cur->bi_cnt) == 0); - bio_get(cur); submit_bio(cur->bi_rw, cur); - bio_put(cur); num_run++; + if (bio_sync(cur)) + num_sync_run++; + + if (need_resched()) { + if (num_sync_run) { + blk_run_backing_dev(bdi, NULL); + num_sync_run = 0; + } + cond_resched(); + } /* * we made progress, there is more work to do and the bdi @@ -208,7 +267,6 @@ loop_lock: */ if (pending && bdi_write_congested(bdi) && num_run > 16 && fs_info->fs_devices->open_devices > 1) { - struct bio *old_head; struct io_context *ioc; ioc = current->io_context; @@ -233,17 +291,17 @@ loop_lock: * against it before looping */ last_waited = ioc->last_waited; + if (need_resched()) { + if (num_sync_run) { + blk_run_backing_dev(bdi, NULL); + num_sync_run = 0; + } + cond_resched(); + } continue; } spin_lock(&device->io_lock); - - old_head = device->pending_bios; - device->pending_bios = pending; - if (device->pending_bio_tail) - tail->bi_next = old_head; - else - device->pending_bio_tail = tail; - + requeue_list(pending_bios, pending, tail); device->running_pending = 1; spin_unlock(&device->io_lock); @@ -251,11 +309,18 @@ loop_lock: goto done; } } + + if (num_sync_run) { + num_sync_run = 0; + blk_run_backing_dev(bdi, NULL); + } + + cond_resched(); if (again) goto loop; spin_lock(&device->io_lock); - if (device->pending_bios) + if (device->pending_bios.head || device->pending_sync_bios.head) goto loop_lock; spin_unlock(&device->io_lock); @@ -2497,7 +2562,7 @@ again: max_errors = 1; } } - if (multi_ret && rw == WRITE && + if (multi_ret && (rw & (1 << BIO_RW)) && stripes_allocated < stripes_required) { stripes_allocated = map->num_stripes; free_extent_map(em); @@ -2762,6 +2827,7 @@ static noinline int schedule_bio(struct btrfs_root *root, int rw, struct bio *bio) { int should_queue = 1; + struct btrfs_pending_bios *pending_bios; /* don't bother with additional async steps for reads, right now */ if (!(rw & (1 << BIO_RW))) { @@ -2783,13 +2849,17 @@ static noinline int schedule_bio(struct btrfs_root *root, bio->bi_rw |= rw; spin_lock(&device->io_lock); + if (bio_sync(bio)) + pending_bios = &device->pending_sync_bios; + else + pending_bios = &device->pending_bios; - if (device->pending_bio_tail) - device->pending_bio_tail->bi_next = bio; + if (pending_bios->tail) + pending_bios->tail->bi_next = bio; - device->pending_bio_tail = bio; - if (!device->pending_bios) - device->pending_bios = bio; + pending_bios->tail = bio; + if (!pending_bios->head) + pending_bios->head = bio; if (device->running_pending) should_queue = 0; diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h index 2185de7..5836327 100644 --- a/fs/btrfs/volumes.h +++ b/fs/btrfs/volumes.h @@ -23,13 +23,22 @@ #include "async-thread.h" struct buffer_head; +struct btrfs_pending_bios { + struct bio *head; + struct bio *tail; +}; + struct btrfs_device { struct list_head dev_list; struct list_head dev_alloc_list; struct btrfs_fs_devices *fs_devices; struct btrfs_root *dev_root; - struct bio *pending_bios; - struct bio *pending_bio_tail; + + /* regular prio bios */ + struct btrfs_pending_bios pending_bios; + /* WRITE_SYNC bios */ + struct btrfs_pending_bios pending_sync_bios; + int running_pending; u64 generation; -- cgit v0.10.2 From d313d7a31a752c88f7288692bd98e66d0789779b Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Mon, 20 Apr 2009 15:50:09 -0400 Subject: Btrfs: add a priority queue to the async thread helpers Btrfs is using WRITE_SYNC_PLUG to send down synchronous IOs with a higher priority. But, the checksumming helper threads prevent it from being fully effective. There are two problems. First, a big queue of pending checksumming will delay the synchronous IO behind other lower priority writes. Second, the checksumming uses an ordered async work queue. The ordering makes sure that IOs are sent to the block layer in the same order they are sent to the checksumming threads. Usually this gives us less seeky IO. But, when we start mixing IO priorities, the lower priority IO can delay the higher priority IO. This patch solves both problems by adding a high priority list to the async helper threads, and a new btrfs_set_work_high_prio(), which is used to make put a new async work item onto the higher priority list. The ordering is still done on high priority IO, but all of the high priority bios are ordered separately from the low priority bios. This ordering is purely an IO optimization, it is not involved in data or metadata integrity. Signed-off-by: Chris Mason diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c index 51bfdfc..502c3d6 100644 --- a/fs/btrfs/async-thread.c +++ b/fs/btrfs/async-thread.c @@ -25,6 +25,7 @@ #define WORK_QUEUED_BIT 0 #define WORK_DONE_BIT 1 #define WORK_ORDER_DONE_BIT 2 +#define WORK_HIGH_PRIO_BIT 3 /* * container for the kthread task pointer and the list of pending work @@ -36,6 +37,7 @@ struct btrfs_worker_thread { /* list of struct btrfs_work that are waiting for service */ struct list_head pending; + struct list_head prio_pending; /* list of worker threads from struct btrfs_workers */ struct list_head worker_list; @@ -103,10 +105,16 @@ static noinline int run_ordered_completions(struct btrfs_workers *workers, spin_lock_irqsave(&workers->lock, flags); - while (!list_empty(&workers->order_list)) { - work = list_entry(workers->order_list.next, - struct btrfs_work, order_list); - + while (1) { + if (!list_empty(&workers->prio_order_list)) { + work = list_entry(workers->prio_order_list.next, + struct btrfs_work, order_list); + } else if (!list_empty(&workers->order_list)) { + work = list_entry(workers->order_list.next, + struct btrfs_work, order_list); + } else { + break; + } if (!test_bit(WORK_DONE_BIT, &work->flags)) break; @@ -143,8 +151,14 @@ static int worker_loop(void *arg) do { spin_lock_irq(&worker->lock); again_locked: - while (!list_empty(&worker->pending)) { - cur = worker->pending.next; + while (1) { + if (!list_empty(&worker->prio_pending)) + cur = worker->prio_pending.next; + else if (!list_empty(&worker->pending)) + cur = worker->pending.next; + else + break; + work = list_entry(cur, struct btrfs_work, list); list_del(&work->list); clear_bit(WORK_QUEUED_BIT, &work->flags); @@ -163,7 +177,6 @@ again_locked: spin_lock_irq(&worker->lock); check_idle_worker(worker); - } if (freezing(current)) { worker->working = 0; @@ -178,7 +191,8 @@ again_locked: * jump_in? */ smp_mb(); - if (!list_empty(&worker->pending)) + if (!list_empty(&worker->pending) || + !list_empty(&worker->prio_pending)) continue; /* @@ -191,7 +205,8 @@ again_locked: */ schedule_timeout(1); smp_mb(); - if (!list_empty(&worker->pending)) + if (!list_empty(&worker->pending) || + !list_empty(&worker->prio_pending)) continue; if (kthread_should_stop()) @@ -200,7 +215,8 @@ again_locked: /* still no more work?, sleep for real */ spin_lock_irq(&worker->lock); set_current_state(TASK_INTERRUPTIBLE); - if (!list_empty(&worker->pending)) + if (!list_empty(&worker->pending) || + !list_empty(&worker->prio_pending)) goto again_locked; /* @@ -248,6 +264,7 @@ void btrfs_init_workers(struct btrfs_workers *workers, char *name, int max) INIT_LIST_HEAD(&workers->worker_list); INIT_LIST_HEAD(&workers->idle_list); INIT_LIST_HEAD(&workers->order_list); + INIT_LIST_HEAD(&workers->prio_order_list); spin_lock_init(&workers->lock); workers->max_workers = max; workers->idle_thresh = 32; @@ -273,6 +290,7 @@ int btrfs_start_workers(struct btrfs_workers *workers, int num_workers) } INIT_LIST_HEAD(&worker->pending); + INIT_LIST_HEAD(&worker->prio_pending); INIT_LIST_HEAD(&worker->worker_list); spin_lock_init(&worker->lock); atomic_set(&worker->num_pending, 0); @@ -396,7 +414,10 @@ int btrfs_requeue_work(struct btrfs_work *work) goto out; spin_lock_irqsave(&worker->lock, flags); - list_add_tail(&work->list, &worker->pending); + if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags)) + list_add_tail(&work->list, &worker->prio_pending); + else + list_add_tail(&work->list, &worker->pending); atomic_inc(&worker->num_pending); /* by definition we're busy, take ourselves off the idle @@ -422,6 +443,11 @@ out: return 0; } +void btrfs_set_work_high_prio(struct btrfs_work *work) +{ + set_bit(WORK_HIGH_PRIO_BIT, &work->flags); +} + /* * places a struct btrfs_work into the pending queue of one of the kthreads */ @@ -438,7 +464,12 @@ int btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work) worker = find_worker(workers); if (workers->ordered) { spin_lock_irqsave(&workers->lock, flags); - list_add_tail(&work->order_list, &workers->order_list); + if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags)) { + list_add_tail(&work->order_list, + &workers->prio_order_list); + } else { + list_add_tail(&work->order_list, &workers->order_list); + } spin_unlock_irqrestore(&workers->lock, flags); } else { INIT_LIST_HEAD(&work->order_list); @@ -446,7 +477,10 @@ int btrfs_queue_worker(struct btrfs_workers *workers, struct btrfs_work *work) spin_lock_irqsave(&worker->lock, flags); - list_add_tail(&work->list, &worker->pending); + if (test_bit(WORK_HIGH_PRIO_BIT, &work->flags)) + list_add_tail(&work->list, &worker->prio_pending); + else + list_add_tail(&work->list, &worker->pending); atomic_inc(&worker->num_pending); check_busy_worker(worker); diff --git a/fs/btrfs/async-thread.h b/fs/btrfs/async-thread.h index 31be4ed..1b511c1 100644 --- a/fs/btrfs/async-thread.h +++ b/fs/btrfs/async-thread.h @@ -85,6 +85,7 @@ struct btrfs_workers { * of work items waiting for completion */ struct list_head order_list; + struct list_head prio_order_list; /* lock for finding the next worker thread to queue on */ spinlock_t lock; @@ -98,4 +99,5 @@ 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, char *name, int max); int btrfs_requeue_work(struct btrfs_work *work); +void btrfs_set_work_high_prio(struct btrfs_work *work); #endif diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index fec18b4..a6b8374 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -579,6 +579,10 @@ int btrfs_wq_submit_bio(struct btrfs_fs_info *fs_info, struct inode *inode, async->bio_flags = bio_flags; atomic_inc(&fs_info->nr_async_submits); + + if (rw & (1 << BIO_RW_SYNCIO)) + btrfs_set_work_high_prio(&async->work); + btrfs_queue_worker(&fs_info->workers, &async->work); #if 0 int limit = btrfs_async_submit_limit(fs_info); @@ -656,6 +660,7 @@ static int btree_submit_bio_hook(struct inode *inode, int rw, struct bio *bio, return btrfs_map_bio(BTRFS_I(inode)->root, rw, bio, mirror_num, 0); } + /* * kthread helpers are used to submit writes so that checksumming * can happen in parallel across all CPUs diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 483b672..5d66cb2 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -2501,7 +2501,7 @@ int extent_write_full_page(struct extent_io_tree *tree, struct page *page, }; struct writeback_control wbc_writepages = { .bdi = wbc->bdi, - .sync_mode = WB_SYNC_NONE, + .sync_mode = wbc->sync_mode, .older_than_this = NULL, .nr_to_write = 64, .range_start = page_offset(page) + PAGE_CACHE_SIZE, diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 9c9fb46..e21c006 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1131,7 +1131,7 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf, if (will_write) { btrfs_fdatawrite_range(inode->i_mapping, pos, pos + write_bytes - 1, - WB_SYNC_NONE); + WB_SYNC_ALL); } else { balance_dirty_pages_ratelimited_nr(inode->i_mapping, num_pages); -- cgit v0.10.2 From 11c8349b4eb68f2b04cd8ece577377e6c0e5dd4b Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Mon, 20 Apr 2009 15:50:09 -0400 Subject: Btrfs: fix oops on page->mapping->host during writepage The extent_io writepage call updates the writepage index in the inode as it makes progress. But, it was doing the update after unlocking the page, which isn't legal because page->mapping can't be trusted once the page is unlocked. This lead to an oops, especially common with compression turned on. The fix here is to update the writeback index before unlocking the page. Signed-off-by: Chris Mason diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c index 5d66cb2..05a1c42 100644 --- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -2104,6 +2104,16 @@ int extent_read_full_page(struct extent_io_tree *tree, struct page *page, return ret; } +static noinline void update_nr_written(struct page *page, + struct writeback_control *wbc, + unsigned long nr_written) +{ + wbc->nr_to_write -= nr_written; + if (wbc->range_cyclic || (wbc->nr_to_write > 0 && + wbc->range_start == 0 && wbc->range_end == LLONG_MAX)) + page->mapping->writeback_index = page->index + nr_written; +} + /* * the writepage semantics are similar to regular writepage. extent * records are inserted to lock ranges in the tree, and as dirty areas @@ -2173,6 +2183,12 @@ static int __extent_writepage(struct page *page, struct writeback_control *wbc, delalloc_end = 0; page_started = 0; if (!epd->extent_locked) { + /* + * make sure the wbc mapping index is at least updated + * to this page. + */ + update_nr_written(page, wbc, 0); + while (delalloc_end < page_end) { nr_delalloc = find_lock_delalloc_range(inode, tree, page, @@ -2194,7 +2210,13 @@ static int __extent_writepage(struct page *page, struct writeback_control *wbc, */ if (page_started) { ret = 0; - goto update_nr_written; + /* + * we've unlocked the page, so we can't update + * the mapping's writeback index, just update + * nr_to_write. + */ + wbc->nr_to_write -= nr_written; + goto done_unlocked; } } lock_extent(tree, start, page_end, GFP_NOFS); @@ -2207,13 +2229,18 @@ static int __extent_writepage(struct page *page, struct writeback_control *wbc, if (ret == -EAGAIN) { unlock_extent(tree, start, page_end, GFP_NOFS); redirty_page_for_writepage(wbc, page); + update_nr_written(page, wbc, nr_written); unlock_page(page); ret = 0; - goto update_nr_written; + goto done_unlocked; } } - nr_written++; + /* + * we don't want to touch the inode after unlocking the page, + * so we update the mapping writeback index now + */ + update_nr_written(page, wbc, nr_written + 1); end = page_end; if (test_range_bit(tree, start, page_end, EXTENT_DELALLOC, 0)) @@ -2345,11 +2372,8 @@ done: unlock_extent(tree, unlock_start, page_end, GFP_NOFS); unlock_page(page); -update_nr_written: - wbc->nr_to_write -= nr_written; - if (wbc->range_cyclic || (wbc->nr_to_write > 0 && - wbc->range_start == 0 && wbc->range_end == LLONG_MAX)) - page->mapping->writeback_index = page->index + nr_written; +done_unlocked: + return 0; } -- cgit v0.10.2 From 8c594ea81d7abbbffdda447b127f8ba8d76f319d Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Mon, 20 Apr 2009 15:50:10 -0400 Subject: Btrfs: use the right node in reada_for_balance reada_for_balance was using the wrong index into the path node array, so it wasn't reading the right blocks. We never directly used the results of the read done by this function because the btree search is started over at the end. This fixes reada_for_balance to reada in the correct node and to avoid searching past the last slot in the node. It also makes sure to hold the parent lock while we are finding the nodes to read. Signed-off-by: Chris Mason diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index e5b2533..a99f1c2 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -1325,12 +1325,12 @@ static noinline int reada_for_balance(struct btrfs_root *root, int ret = 0; int blocksize; - parent = path->nodes[level - 1]; + parent = path->nodes[level + 1]; if (!parent) return 0; nritems = btrfs_header_nritems(parent); - slot = path->slots[level]; + slot = path->slots[level + 1]; blocksize = btrfs_level_size(root, level); if (slot > 0) { @@ -1341,7 +1341,7 @@ static noinline int reada_for_balance(struct btrfs_root *root, block1 = 0; free_extent_buffer(eb); } - if (slot < nritems) { + if (slot + 1 < nritems) { block2 = btrfs_node_blockptr(parent, slot + 1); gen = btrfs_node_ptr_generation(parent, slot + 1); eb = btrfs_find_tree_block(root, block2, blocksize); @@ -1351,7 +1351,11 @@ static noinline int reada_for_balance(struct btrfs_root *root, } if (block1 || block2) { ret = -EAGAIN; + + /* release the whole path */ btrfs_release_path(root, path); + + /* read the blocks */ if (block1) readahead_tree_block(root, block1, blocksize, 0); if (block2) @@ -1361,7 +1365,7 @@ static noinline int reada_for_balance(struct btrfs_root *root, eb = read_tree_block(root, block1, blocksize, 0); free_extent_buffer(eb); } - if (block1) { + if (block2) { eb = read_tree_block(root, block2, blocksize, 0); free_extent_buffer(eb); } @@ -1481,12 +1485,15 @@ read_block_for_search(struct btrfs_trans_handle *trans, * of the btree by dropping locks before * we read. */ - btrfs_release_path(NULL, p); + btrfs_unlock_up_safe(p, level + 1); + btrfs_set_path_blocking(p); + if (tmp) free_extent_buffer(tmp); if (p->reada) reada_for_search(root, p, level, slot, key->objectid); + btrfs_release_path(NULL, p); tmp = read_tree_block(root, blocknr, blocksize, gen); if (tmp) free_extent_buffer(tmp); -- cgit v0.10.2 From 546888da82082555a56528730a83f0afd12f33bf Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Tue, 21 Apr 2009 11:53:38 -0400 Subject: Btrfs: fix btrfs fallocate oops and deadlock Btrfs fallocate was incorrectly starting a transaction with a lock held on the extent_io tree for the file, which could deadlock. Strictly speaking it was using join_transaction which would be safe, but it is better to move the transaction outside of the lock. When preallocated extents are overwritten, btrfs_mark_buffer_dirty was being called on an unlocked buffer. This was triggering an assertion and oops because the lock is supposed to be held. The bug was calling btrfs_mark_buffer_dirty on a leaf after btrfs_del_item had been run. btrfs_del_item takes care of dirtying things, so the solution is a to skip the btrfs_mark_buffer_dirty call in this case. Signed-off-by: Chris Mason diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index e21c006..482f8db 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -830,7 +830,7 @@ again: ret = btrfs_del_items(trans, root, path, del_slot, del_nr); BUG_ON(ret); - goto done; + goto release; } else if (split == start) { if (locked_end < extent_end) { ret = try_lock_extent(&BTRFS_I(inode)->io_tree, @@ -926,6 +926,8 @@ again: } done: btrfs_mark_buffer_dirty(leaf); + +release: btrfs_release_path(root, path); if (split_end && split == start) { split = end; diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index a0d1dd4..65219f6 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -4970,10 +4970,10 @@ out_fail: return err; } -static int prealloc_file_range(struct inode *inode, u64 start, u64 end, +static int prealloc_file_range(struct btrfs_trans_handle *trans, + struct inode *inode, u64 start, u64 end, u64 alloc_hint, int mode) { - struct btrfs_trans_handle *trans; struct btrfs_root *root = BTRFS_I(inode)->root; struct btrfs_key ins; u64 alloc_size; @@ -4981,10 +4981,6 @@ static int prealloc_file_range(struct inode *inode, u64 start, u64 end, u64 num_bytes = end - start; int ret = 0; - trans = btrfs_join_transaction(root, 1); - BUG_ON(!trans); - btrfs_set_trans_block_group(trans, inode); - while (num_bytes > 0) { alloc_size = min(num_bytes, root->fs_info->max_extent); ret = btrfs_reserve_extent(trans, root, alloc_size, @@ -5015,7 +5011,6 @@ out: BUG_ON(ret); } - btrfs_end_transaction(trans, root); return ret; } @@ -5029,11 +5024,18 @@ static long btrfs_fallocate(struct inode *inode, int mode, u64 alloc_hint = 0; u64 mask = BTRFS_I(inode)->root->sectorsize - 1; struct extent_map *em; + struct btrfs_trans_handle *trans; int ret; alloc_start = offset & ~mask; alloc_end = (offset + len + mask) & ~mask; + /* + * wait for ordered IO before we have any locks. We'll loop again + * below with the locks held. + */ + btrfs_wait_ordered_range(inode, alloc_start, alloc_end - alloc_start); + mutex_lock(&inode->i_mutex); if (alloc_start > inode->i_size) { ret = btrfs_cont_expand(inode, alloc_start); @@ -5043,6 +5045,16 @@ static long btrfs_fallocate(struct inode *inode, int mode, while (1) { struct btrfs_ordered_extent *ordered; + + trans = btrfs_start_transaction(BTRFS_I(inode)->root, 1); + if (!trans) { + ret = -EIO; + goto out; + } + + /* the extent lock is ordered inside the running + * transaction + */ lock_extent(&BTRFS_I(inode)->io_tree, alloc_start, alloc_end - 1, GFP_NOFS); ordered = btrfs_lookup_first_ordered_extent(inode, @@ -5053,6 +5065,12 @@ static long btrfs_fallocate(struct inode *inode, int mode, btrfs_put_ordered_extent(ordered); unlock_extent(&BTRFS_I(inode)->io_tree, alloc_start, alloc_end - 1, GFP_NOFS); + btrfs_end_transaction(trans, BTRFS_I(inode)->root); + + /* + * we can't wait on the range with the transaction + * running or with the extent lock held + */ btrfs_wait_ordered_range(inode, alloc_start, alloc_end - alloc_start); } else { @@ -5070,7 +5088,7 @@ static long btrfs_fallocate(struct inode *inode, int mode, last_byte = min(extent_map_end(em), alloc_end); last_byte = (last_byte + mask) & ~mask; if (em->block_start == EXTENT_MAP_HOLE) { - ret = prealloc_file_range(inode, cur_offset, + ret = prealloc_file_range(trans, inode, cur_offset, last_byte, alloc_hint, mode); if (ret < 0) { free_extent_map(em); @@ -5089,6 +5107,8 @@ static long btrfs_fallocate(struct inode *inode, int mode, } unlock_extent(&BTRFS_I(inode)->io_tree, alloc_start, alloc_end - 1, GFP_NOFS); + + btrfs_end_transaction(trans, BTRFS_I(inode)->root); out: mutex_unlock(&inode->i_mutex); return ret; -- cgit v0.10.2