diff options
Diffstat (limited to 'fs/btrfs/block-group.c')
| -rw-r--r-- | fs/btrfs/block-group.c | 242 |
1 files changed, 171 insertions, 71 deletions
diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c index a3b830b8410a..444e9c89ff3e 100644 --- a/fs/btrfs/block-group.c +++ b/fs/btrfs/block-group.c @@ -1,5 +1,6 @@ // SPDX-License-Identifier: GPL-2.0 +#include <linux/list_sort.h> #include "misc.h" #include "ctree.h" #include "block-group.h" @@ -144,6 +145,7 @@ void btrfs_put_block_group(struct btrfs_block_group *cache) */ WARN_ON(!RB_EMPTY_ROOT(&cache->full_stripe_locks_root.root)); kfree(cache->free_space_ctl); + kfree(cache->physical_map); kfree(cache); } } @@ -902,6 +904,7 @@ int btrfs_remove_block_group(struct btrfs_trans_handle *trans, spin_unlock(&cluster->refill_lock); btrfs_clear_treelog_bg(block_group); + btrfs_clear_data_reloc_bg(block_group); path = btrfs_alloc_path(); if (!path) { @@ -1484,6 +1487,21 @@ void btrfs_mark_bg_unused(struct btrfs_block_group *bg) spin_unlock(&fs_info->unused_bgs_lock); } +/* + * We want block groups with a low number of used bytes to be in the beginning + * of the list, so they will get reclaimed first. + */ +static int reclaim_bgs_cmp(void *unused, const struct list_head *a, + const struct list_head *b) +{ + const struct btrfs_block_group *bg1, *bg2; + + bg1 = list_entry(a, struct btrfs_block_group, bg_list); + bg2 = list_entry(b, struct btrfs_block_group, bg_list); + + return bg1->used > bg2->used; +} + void btrfs_reclaim_bgs_work(struct work_struct *work) { struct btrfs_fs_info *fs_info = @@ -1508,6 +1526,12 @@ void btrfs_reclaim_bgs_work(struct work_struct *work) } spin_lock(&fs_info->unused_bgs_lock); + /* + * Sort happens under lock because we can't simply splice it and sort. + * The block groups might still be in use and reachable via bg_list, + * and their presence in the reclaim_bgs list must be preserved. + */ + list_sort(NULL, &fs_info->reclaim_bgs, reclaim_bgs_cmp); while (!list_empty(&fs_info->reclaim_bgs)) { u64 zone_unusable; int ret = 0; @@ -1895,6 +1919,7 @@ static struct btrfs_block_group *btrfs_create_block_group_cache( INIT_LIST_HEAD(&cache->discard_list); INIT_LIST_HEAD(&cache->dirty_list); INIT_LIST_HEAD(&cache->io_list); + INIT_LIST_HEAD(&cache->active_bg_list); btrfs_init_free_space_ctl(cache, cache->free_space_ctl); atomic_set(&cache->frozen, 0); mutex_init(&cache->free_space_lock); @@ -2035,6 +2060,8 @@ static int read_one_block_group(struct btrfs_fs_info *info, */ if (btrfs_is_zoned(info)) { btrfs_calc_zone_unusable(cache); + /* Should not have any excluded extents. Just in case, though. */ + btrfs_free_excluded_extents(cache); } else if (cache->length == cache->used) { cache->last_byte_to_unpin = (u64)-1; cache->cached = BTRFS_CACHE_FINISHED; @@ -2062,15 +2089,18 @@ static int read_one_block_group(struct btrfs_fs_info *info, link_block_group(cache); set_avail_alloc_bits(info, cache->flags); - if (btrfs_chunk_readonly(info, cache->start)) { + if (btrfs_chunk_writeable(info, cache->start)) { + if (cache->used == 0) { + ASSERT(list_empty(&cache->bg_list)); + if (btrfs_test_opt(info, DISCARD_ASYNC)) + btrfs_discard_queue_work(&info->discard_ctl, cache); + else + btrfs_mark_bg_unused(cache); + } + } else { inc_block_group_ro(cache, 1); - } else if (cache->used == 0) { - ASSERT(list_empty(&cache->bg_list)); - if (btrfs_test_opt(info, DISCARD_ASYNC)) - btrfs_discard_queue_work(&info->discard_ctl, cache); - else - btrfs_mark_bg_unused(cache); } + return 0; error: btrfs_put_block_group(cache); @@ -2438,6 +2468,12 @@ struct btrfs_block_group *btrfs_make_block_group(struct btrfs_trans_handle *tran return ERR_PTR(ret); } + /* + * New block group is likely to be used soon. Try to activate it now. + * Failure is OK for now. + */ + btrfs_zone_activate(cache); + ret = exclude_super_stripes(cache); if (ret) { /* We may have excluded something, so call this just in case */ @@ -2479,7 +2515,8 @@ struct btrfs_block_group *btrfs_make_block_group(struct btrfs_trans_handle *tran */ trace_btrfs_add_block_group(fs_info, cache, 1); btrfs_update_space_info(fs_info, cache->flags, size, bytes_used, - cache->bytes_super, 0, &cache->space_info); + cache->bytes_super, cache->zone_unusable, + &cache->space_info); btrfs_update_global_block_rsv(fs_info); link_block_group(cache); @@ -2594,7 +2631,9 @@ void btrfs_dec_block_group_ro(struct btrfs_block_group *cache) if (!--cache->ro) { if (btrfs_is_zoned(cache->fs_info)) { /* Migrate zone_unusable bytes back */ - cache->zone_unusable = cache->alloc_offset - cache->used; + cache->zone_unusable = + (cache->alloc_offset - cache->used) + + (cache->length - cache->zone_capacity); sinfo->bytes_zone_unusable += cache->zone_unusable; sinfo->bytes_readonly -= cache->zone_unusable; } @@ -3143,7 +3182,7 @@ int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans) } int btrfs_update_block_group(struct btrfs_trans_handle *trans, - u64 bytenr, u64 num_bytes, int alloc) + u64 bytenr, u64 num_bytes, bool alloc) { struct btrfs_fs_info *info = trans->fs_info; struct btrfs_block_group *cache = NULL; @@ -3380,36 +3419,17 @@ static int do_chunk_alloc(struct btrfs_trans_handle *trans, u64 flags) */ check_system_chunk(trans, flags); - bg = btrfs_alloc_chunk(trans, flags); + bg = btrfs_create_chunk(trans, flags); if (IS_ERR(bg)) { ret = PTR_ERR(bg); goto out; } - /* - * If this is a system chunk allocation then stop right here and do not - * add the chunk item to the chunk btree. This is to prevent a deadlock - * because this system chunk allocation can be triggered while COWing - * some extent buffer of the chunk btree and while holding a lock on a - * parent extent buffer, in which case attempting to insert the chunk - * item (or update the device item) would result in a deadlock on that - * parent extent buffer. In this case defer the chunk btree updates to - * the second phase of chunk allocation and keep our reservation until - * the second phase completes. - * - * This is a rare case and can only be triggered by the very few cases - * we have where we need to touch the chunk btree outside chunk allocation - * and chunk removal. These cases are basically adding a device, removing - * a device or resizing a device. - */ - if (flags & BTRFS_BLOCK_GROUP_SYSTEM) - return 0; - ret = btrfs_chunk_alloc_add_chunk_item(trans, bg); /* * Normally we are not expected to fail with -ENOSPC here, since we have * previously reserved space in the system space_info and allocated one - * new system chunk if necessary. However there are two exceptions: + * new system chunk if necessary. However there are three exceptions: * * 1) We may have enough free space in the system space_info but all the * existing system block groups have a profile which can not be used @@ -3435,13 +3455,20 @@ static int do_chunk_alloc(struct btrfs_trans_handle *trans, u64 flags) * with enough free space got turned into RO mode by a running scrub, * and in this case we have to allocate a new one and retry. We only * need do this allocate and retry once, since we have a transaction - * handle and scrub uses the commit root to search for block groups. + * handle and scrub uses the commit root to search for block groups; + * + * 3) We had one system block group with enough free space when we called + * check_system_chunk(), but after that, right before we tried to + * allocate the last extent buffer we needed, a discard operation came + * in and it temporarily removed the last free space entry from the + * block group (discard removes a free space entry, discards it, and + * then adds back the entry to the block group cache). */ if (ret == -ENOSPC) { const u64 sys_flags = btrfs_system_alloc_profile(trans->fs_info); struct btrfs_block_group *sys_bg; - sys_bg = btrfs_alloc_chunk(trans, sys_flags); + sys_bg = btrfs_create_chunk(trans, sys_flags); if (IS_ERR(sys_bg)) { ret = PTR_ERR(sys_bg); btrfs_abort_transaction(trans, ret); @@ -3519,7 +3546,15 @@ out: * properly, either intentionally or as a bug. One example where this is * done intentionally is fsync, as it does not reserve any transaction units * and ends up allocating a variable number of metadata extents for log - * tree extent buffers. + * tree extent buffers; + * + * 4) The task has reserved enough transaction units / metadata space, but right + * before it tries to allocate the last extent buffer it needs, a discard + * operation comes in and, temporarily, removes the last free space entry from + * the only metadata block group that had free space (discard starts by + * removing a free space entry from a block group, then does the discard + * operation and, once it's done, it adds back the free space entry to the + * block group). * * We also need this 2 phases setup when adding a device to a filesystem with * a seed device - we must create new metadata and system chunks without adding @@ -3537,14 +3572,14 @@ out: * This has happened before and commit eafa4fd0ad0607 ("btrfs: fix exhaustion of * the system chunk array due to concurrent allocations") provides more details. * - * For allocation of system chunks, we defer the updates and insertions into the - * chunk btree to phase 2. This is to prevent deadlocks on extent buffers because - * if the chunk allocation is triggered while COWing an extent buffer of the - * chunk btree, we are holding a lock on the parent of that extent buffer and - * doing the chunk btree updates and insertions can require locking that parent. - * This is for the very few and rare cases where we update the chunk btree that - * are not chunk allocation or chunk removal: adding a device, removing a device - * or resizing a device. + * Allocation of system chunks does not happen through this function. A task that + * needs to update the chunk btree (the only btree that uses system chunks), must + * preallocate chunk space by calling either check_system_chunk() or + * btrfs_reserve_chunk_metadata() - the former is used when allocating a data or + * metadata chunk or when removing a chunk, while the later is used before doing + * a modification to the chunk btree - use cases for the later are adding, + * removing and resizing a device as well as relocation of a system chunk. + * See the comment below for more details. * * The reservation of system space, done through check_system_chunk(), as well * as all the updates and insertions into the chunk btree must be done while @@ -3581,11 +3616,27 @@ int btrfs_chunk_alloc(struct btrfs_trans_handle *trans, u64 flags, if (trans->allocating_chunk) return -ENOSPC; /* - * If we are removing a chunk, don't re-enter or we would deadlock. - * System space reservation and system chunk allocation is done by the - * chunk remove operation (btrfs_remove_chunk()). + * Allocation of system chunks can not happen through this path, as we + * could end up in a deadlock if we are allocating a data or metadata + * chunk and there is another task modifying the chunk btree. + * + * This is because while we are holding the chunk mutex, we will attempt + * to add the new chunk item to the chunk btree or update an existing + * device item in the chunk btree, while the other task that is modifying + * the chunk btree is attempting to COW an extent buffer while holding a + * lock on it and on its parent - if the COW operation triggers a system + * chunk allocation, then we can deadlock because we are holding the + * chunk mutex and we may need to access that extent buffer or its parent + * in order to add the chunk item or update a device item. + * + * Tasks that want to modify the chunk tree should reserve system space + * before updating the chunk btree, by calling either + * btrfs_reserve_chunk_metadata() or check_system_chunk(). + * It's possible that after a task reserves the space, it still ends up + * here - this happens in the cases described above at do_chunk_alloc(). + * The task will have to either retry or fail. */ - if (trans->removing_chunk) + if (flags & BTRFS_BLOCK_GROUP_SYSTEM) return -ENOSPC; space_info = btrfs_find_space_info(fs_info, flags); @@ -3684,17 +3735,14 @@ static u64 get_profile_num_devs(struct btrfs_fs_info *fs_info, u64 type) return num_dev; } -/* - * Reserve space in the system space for allocating or removing a chunk - */ -void check_system_chunk(struct btrfs_trans_handle *trans, u64 type) +static void reserve_chunk_space(struct btrfs_trans_handle *trans, + u64 bytes, + u64 type) { struct btrfs_fs_info *fs_info = trans->fs_info; struct btrfs_space_info *info; u64 left; - u64 thresh; int ret = 0; - u64 num_devs; /* * Needed because we can end up allocating a system chunk and for an @@ -3707,19 +3755,13 @@ void check_system_chunk(struct btrfs_trans_handle *trans, u64 type) left = info->total_bytes - btrfs_space_info_used(info, true); spin_unlock(&info->lock); - num_devs = get_profile_num_devs(fs_info, type); - - /* num_devs device items to update and 1 chunk item to add or remove */ - thresh = btrfs_calc_metadata_size(fs_info, num_devs) + - btrfs_calc_insert_metadata_size(fs_info, 1); - - if (left < thresh && btrfs_test_opt(fs_info, ENOSPC_DEBUG)) { + if (left < bytes && btrfs_test_opt(fs_info, ENOSPC_DEBUG)) { btrfs_info(fs_info, "left=%llu, need=%llu, flags=%llu", - left, thresh, type); + left, bytes, type); btrfs_dump_space_info(fs_info, info, 0, 0); } - if (left < thresh) { + if (left < bytes) { u64 flags = btrfs_system_alloc_profile(fs_info); struct btrfs_block_group *bg; @@ -3728,21 +3770,20 @@ void check_system_chunk(struct btrfs_trans_handle *trans, u64 type) * needing it, as we might not need to COW all nodes/leafs from * the paths we visit in the chunk tree (they were already COWed * or created in the current transaction for example). - * - * Also, if our caller is allocating a system chunk, do not - * attempt to insert the chunk item in the chunk btree, as we - * could deadlock on an extent buffer since our caller may be - * COWing an extent buffer from the chunk btree. */ - bg = btrfs_alloc_chunk(trans, flags); + bg = btrfs_create_chunk(trans, flags); if (IS_ERR(bg)) { ret = PTR_ERR(bg); - } else if (!(type & BTRFS_BLOCK_GROUP_SYSTEM)) { + } else { /* * If we fail to add the chunk item here, we end up * trying again at phase 2 of chunk allocation, at * btrfs_create_pending_block_groups(). So ignore - * any error here. + * any error here. An ENOSPC here could happen, due to + * the cases described at do_chunk_alloc() - the system + * block group we just created was just turned into RO + * mode by a scrub for example, or a running discard + * temporarily removed its free space entries, etc. */ btrfs_chunk_alloc_add_chunk_item(trans, bg); } @@ -3751,12 +3792,61 @@ void check_system_chunk(struct btrfs_trans_handle *trans, u64 type) if (!ret) { ret = btrfs_block_rsv_add(fs_info->chunk_root, &fs_info->chunk_block_rsv, - thresh, BTRFS_RESERVE_NO_FLUSH); + bytes, BTRFS_RESERVE_NO_FLUSH); if (!ret) - trans->chunk_bytes_reserved += thresh; + trans->chunk_bytes_reserved += bytes; } } +/* + * Reserve space in the system space for allocating or removing a chunk. + * The caller must be holding fs_info->chunk_mutex. + */ +void check_system_chunk(struct btrfs_trans_handle *trans, u64 type) +{ + struct btrfs_fs_info *fs_info = trans->fs_info; + const u64 num_devs = get_profile_num_devs(fs_info, type); + u64 bytes; + + /* num_devs device items to update and 1 chunk item to add or remove. */ + bytes = btrfs_calc_metadata_size(fs_info, num_devs) + + btrfs_calc_insert_metadata_size(fs_info, 1); + + reserve_chunk_space(trans, bytes, type); +} + +/* + * Reserve space in the system space, if needed, for doing a modification to the + * chunk btree. + * + * @trans: A transaction handle. + * @is_item_insertion: Indicate if the modification is for inserting a new item + * in the chunk btree or if it's for the deletion or update + * of an existing item. + * + * This is used in a context where we need to update the chunk btree outside + * block group allocation and removal, to avoid a deadlock with a concurrent + * task that is allocating a metadata or data block group and therefore needs to + * update the chunk btree while holding the chunk mutex. After the update to the + * chunk btree is done, btrfs_trans_release_chunk_metadata() should be called. + * + */ +void btrfs_reserve_chunk_metadata(struct btrfs_trans_handle *trans, + bool is_item_insertion) +{ + struct btrfs_fs_info *fs_info = trans->fs_info; + u64 bytes; + + if (is_item_insertion) + bytes = btrfs_calc_insert_metadata_size(fs_info, 1); + else + bytes = btrfs_calc_metadata_size(fs_info, 1); + + mutex_lock(&fs_info->chunk_mutex); + reserve_chunk_space(trans, bytes, BTRFS_BLOCK_GROUP_SYSTEM); + mutex_unlock(&fs_info->chunk_mutex); +} + void btrfs_put_block_group_cache(struct btrfs_fs_info *info) { struct btrfs_block_group *block_group; @@ -3833,6 +3923,16 @@ int btrfs_free_block_groups(struct btrfs_fs_info *info) } spin_unlock(&info->unused_bgs_lock); + spin_lock(&info->zone_active_bgs_lock); + while (!list_empty(&info->zone_active_bgs)) { + block_group = list_first_entry(&info->zone_active_bgs, + struct btrfs_block_group, + active_bg_list); + list_del_init(&block_group->active_bg_list); + btrfs_put_block_group(block_group); + } + spin_unlock(&info->zone_active_bgs_lock); + spin_lock(&info->block_group_cache_lock); while ((n = rb_last(&info->block_group_cache_tree)) != NULL) { block_group = rb_entry(n, struct btrfs_block_group, |