// SPDX-License-Identifier: GPL-2.0 #include <linux/sizes.h> #include <linux/list_sort.h> #include "misc.h" #include "ctree.h" #include "block-group.h" #include "space-info.h" #include "disk-io.h" #include "free-space-cache.h" #include "free-space-tree.h" #include "volumes.h" #include "transaction.h" #include "ref-verify.h" #include "sysfs.h" #include "tree-log.h" #include "delalloc-space.h" #include "discard.h" #include "raid56.h" #include "zoned.h" #include "fs.h" #include "accessors.h" #include "extent-tree.h" #ifdef CONFIG_BTRFS_DEBUG int btrfs_should_fragment_free_space(struct btrfs_block_group *block_group) { … } #endif /* * Return target flags in extended format or 0 if restripe for this chunk_type * is not in progress * * Should be called with balance_lock held */ static u64 get_restripe_target(struct btrfs_fs_info *fs_info, u64 flags) { … } /* * @flags: available profiles in extended format (see ctree.h) * * Return reduced profile in chunk format. If profile changing is in progress * (either running or paused) picks the target profile (if it's already * available), otherwise falls back to plain reducing. */ static u64 btrfs_reduce_alloc_profile(struct btrfs_fs_info *fs_info, u64 flags) { … } u64 btrfs_get_alloc_profile(struct btrfs_fs_info *fs_info, u64 orig_flags) { … } void btrfs_get_block_group(struct btrfs_block_group *cache) { … } void btrfs_put_block_group(struct btrfs_block_group *cache) { … } /* * This adds the block group to the fs_info rb tree for the block group cache */ static int btrfs_add_block_group_cache(struct btrfs_fs_info *info, struct btrfs_block_group *block_group) { … } /* * This will return the block group at or after bytenr if contains is 0, else * it will return the block group that contains the bytenr */ static struct btrfs_block_group *block_group_cache_tree_search( struct btrfs_fs_info *info, u64 bytenr, int contains) { … } /* * Return the block group that starts at or after bytenr */ struct btrfs_block_group *btrfs_lookup_first_block_group( struct btrfs_fs_info *info, u64 bytenr) { … } /* * Return the block group that contains the given bytenr */ struct btrfs_block_group *btrfs_lookup_block_group( struct btrfs_fs_info *info, u64 bytenr) { … } struct btrfs_block_group *btrfs_next_block_group( struct btrfs_block_group *cache) { … } /* * Check if we can do a NOCOW write for a given extent. * * @fs_info: The filesystem information object. * @bytenr: Logical start address of the extent. * * Check if we can do a NOCOW write for the given extent, and increments the * number of NOCOW writers in the block group that contains the extent, as long * as the block group exists and it's currently not in read-only mode. * * Returns: A non-NULL block group pointer if we can do a NOCOW write, the caller * is responsible for calling btrfs_dec_nocow_writers() later. * * Or NULL if we can not do a NOCOW write */ struct btrfs_block_group *btrfs_inc_nocow_writers(struct btrfs_fs_info *fs_info, u64 bytenr) { … } /* * Decrement the number of NOCOW writers in a block group. * * This is meant to be called after a previous call to btrfs_inc_nocow_writers(), * and on the block group returned by that call. Typically this is called after * creating an ordered extent for a NOCOW write, to prevent races with scrub and * relocation. * * After this call, the caller should not use the block group anymore. It it wants * to use it, then it should get a reference on it before calling this function. */ void btrfs_dec_nocow_writers(struct btrfs_block_group *bg) { … } void btrfs_wait_nocow_writers(struct btrfs_block_group *bg) { … } void btrfs_dec_block_group_reservations(struct btrfs_fs_info *fs_info, const u64 start) { … } void btrfs_wait_block_group_reservations(struct btrfs_block_group *bg) { … } struct btrfs_caching_control *btrfs_get_caching_control( struct btrfs_block_group *cache) { … } static void btrfs_put_caching_control(struct btrfs_caching_control *ctl) { … } /* * When we wait for progress in the block group caching, its because our * allocation attempt failed at least once. So, we must sleep and let some * progress happen before we try again. * * This function will sleep at least once waiting for new free space to show * up, and then it will check the block group free space numbers for our min * num_bytes. Another option is to have it go ahead and look in the rbtree for * a free extent of a given size, but this is a good start. * * Callers of this must check if cache->cached == BTRFS_CACHE_ERROR before using * any of the information in this block group. */ void btrfs_wait_block_group_cache_progress(struct btrfs_block_group *cache, u64 num_bytes) { … } static int btrfs_caching_ctl_wait_done(struct btrfs_block_group *cache, struct btrfs_caching_control *caching_ctl) { … } static int btrfs_wait_block_group_cache_done(struct btrfs_block_group *cache) { … } #ifdef CONFIG_BTRFS_DEBUG static void fragment_free_space(struct btrfs_block_group *block_group) { … } #endif /* * Add a free space range to the in memory free space cache of a block group. * This checks if the range contains super block locations and any such * locations are not added to the free space cache. * * @block_group: The target block group. * @start: Start offset of the range. * @end: End offset of the range (exclusive). * @total_added_ret: Optional pointer to return the total amount of space * added to the block group's free space cache. * * Returns 0 on success or < 0 on error. */ int btrfs_add_new_free_space(struct btrfs_block_group *block_group, u64 start, u64 end, u64 *total_added_ret) { … } /* * Get an arbitrary extent item index / max_index through the block group * * @block_group the block group to sample from * @index: the integral step through the block group to grab from * @max_index: the granularity of the sampling * @key: return value parameter for the item we find * * Pre-conditions on indices: * 0 <= index <= max_index * 0 < max_index * * Returns: 0 on success, 1 if the search didn't yield a useful item, negative * error code on error. */ static int sample_block_group_extent_item(struct btrfs_caching_control *caching_ctl, struct btrfs_block_group *block_group, int index, int max_index, struct btrfs_key *found_key) { … } /* * Best effort attempt to compute a block group's size class while caching it. * * @block_group: the block group we are caching * * We cannot infer the size class while adding free space extents, because that * logic doesn't care about contiguous file extents (it doesn't differentiate * between a 100M extent and 100 contiguous 1M extents). So we need to read the * file extent items. Reading all of them is quite wasteful, because usually * only a handful are enough to give a good answer. Therefore, we just grab 5 of * them at even steps through the block group and pick the smallest size class * we see. Since size class is best effort, and not guaranteed in general, * inaccuracy is acceptable. * * To be more explicit about why this algorithm makes sense: * * If we are caching in a block group from disk, then there are three major cases * to consider: * 1. the block group is well behaved and all extents in it are the same size * class. * 2. the block group is mostly one size class with rare exceptions for last * ditch allocations * 3. the block group was populated before size classes and can have a totally * arbitrary mix of size classes. * * In case 1, looking at any extent in the block group will yield the correct * result. For the mixed cases, taking the minimum size class seems like a good * approximation, since gaps from frees will be usable to the size class. For * 2., a small handful of file extents is likely to yield the right answer. For * 3, we can either read every file extent, or admit that this is best effort * anyway and try to stay fast. * * Returns: 0 on success, negative error code on error. */ static int load_block_group_size_class(struct btrfs_caching_control *caching_ctl, struct btrfs_block_group *block_group) { … } static int load_extent_tree_free(struct btrfs_caching_control *caching_ctl) { … } static inline void btrfs_free_excluded_extents(const struct btrfs_block_group *bg) { … } static noinline void caching_thread(struct btrfs_work *work) { … } int btrfs_cache_block_group(struct btrfs_block_group *cache, bool wait) { … } static void clear_avail_alloc_bits(struct btrfs_fs_info *fs_info, u64 flags) { … } /* * Clear incompat bits for the following feature(s): * * - RAID56 - in case there's neither RAID5 nor RAID6 profile block group * in the whole filesystem * * - RAID1C34 - same as above for RAID1C3 and RAID1C4 block groups */ static void clear_incompat_bg_bits(struct btrfs_fs_info *fs_info, u64 flags) { … } static struct btrfs_root *btrfs_block_group_root(struct btrfs_fs_info *fs_info) { … } static int remove_block_group_item(struct btrfs_trans_handle *trans, struct btrfs_path *path, struct btrfs_block_group *block_group) { … } int btrfs_remove_block_group(struct btrfs_trans_handle *trans, struct btrfs_chunk_map *map) { … } struct btrfs_trans_handle *btrfs_start_trans_remove_block_group( struct btrfs_fs_info *fs_info, const u64 chunk_offset) { … } /* * Mark block group @cache read-only, so later write won't happen to block * group @cache. * * If @force is not set, this function will only mark the block group readonly * if we have enough free space (1M) in other metadata/system block groups. * If @force is not set, this function will mark the block group readonly * without checking free space. * * NOTE: This function doesn't care if other block groups can contain all the * data in this block group. That check should be done by relocation routine, * not this function. */ static int inc_block_group_ro(struct btrfs_block_group *cache, int force) { … } static bool clean_pinned_extents(struct btrfs_trans_handle *trans, struct btrfs_block_group *bg) { … } /* * Process the unused_bgs list and remove any that don't have any allocated * space inside of them. */ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info) { … } void btrfs_mark_bg_unused(struct btrfs_block_group *bg) { … } /* * 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) { … } static inline bool btrfs_should_reclaim(struct btrfs_fs_info *fs_info) { … } static bool should_reclaim_block_group(struct btrfs_block_group *bg, u64 bytes_freed) { … } void btrfs_reclaim_bgs_work(struct work_struct *work) { … } void btrfs_reclaim_bgs(struct btrfs_fs_info *fs_info) { … } void btrfs_mark_bg_to_reclaim(struct btrfs_block_group *bg) { … } static int read_bg_from_eb(struct btrfs_fs_info *fs_info, struct btrfs_key *key, struct btrfs_path *path) { … } static int find_first_block_group(struct btrfs_fs_info *fs_info, struct btrfs_path *path, struct btrfs_key *key) { … } static void set_avail_alloc_bits(struct btrfs_fs_info *fs_info, u64 flags) { … } /* * Map a physical disk address to a list of logical addresses. * * @fs_info: the filesystem * @chunk_start: logical address of block group * @physical: physical address to map to logical addresses * @logical: return array of logical addresses which map to @physical * @naddrs: length of @logical * @stripe_len: size of IO stripe for the given block group * * Maps a particular @physical disk address to a list of @logical addresses. * Used primarily to exclude those portions of a block group that contain super * block copies. */ int btrfs_rmap_block(struct btrfs_fs_info *fs_info, u64 chunk_start, u64 physical, u64 **logical, int *naddrs, int *stripe_len) { … } static int exclude_super_stripes(struct btrfs_block_group *cache) { … } static struct btrfs_block_group *btrfs_create_block_group_cache( struct btrfs_fs_info *fs_info, u64 start) { … } /* * Iterate all chunks and verify that each of them has the corresponding block * group */ static int check_chunk_block_group_mappings(struct btrfs_fs_info *fs_info) { … } static int read_one_block_group(struct btrfs_fs_info *info, struct btrfs_block_group_item *bgi, const struct btrfs_key *key, int need_clear) { … } static int fill_dummy_bgs(struct btrfs_fs_info *fs_info) { … } int btrfs_read_block_groups(struct btrfs_fs_info *info) { … } /* * This function, insert_block_group_item(), belongs to the phase 2 of chunk * allocation. * * See the comment at btrfs_chunk_alloc() for details about the chunk allocation * phases. */ static int insert_block_group_item(struct btrfs_trans_handle *trans, struct btrfs_block_group *block_group) { … } static int insert_dev_extent(struct btrfs_trans_handle *trans, struct btrfs_device *device, u64 chunk_offset, u64 start, u64 num_bytes) { … } /* * This function belongs to phase 2. * * See the comment at btrfs_chunk_alloc() for details about the chunk allocation * phases. */ static int insert_dev_extents(struct btrfs_trans_handle *trans, u64 chunk_offset, u64 chunk_size) { … } /* * This function, btrfs_create_pending_block_groups(), belongs to the phase 2 of * chunk allocation. * * See the comment at btrfs_chunk_alloc() for details about the chunk allocation * phases. */ void btrfs_create_pending_block_groups(struct btrfs_trans_handle *trans) { … } /* * For extent tree v2 we use the block_group_item->chunk_offset to point at our * global root id. For v1 it's always set to BTRFS_FIRST_CHUNK_TREE_OBJECTID. */ static u64 calculate_global_root_id(struct btrfs_fs_info *fs_info, u64 offset) { … } struct btrfs_block_group *btrfs_make_block_group(struct btrfs_trans_handle *trans, u64 type, u64 chunk_offset, u64 size) { … } /* * Mark one block group RO, can be called several times for the same block * group. * * @cache: the destination block group * @do_chunk_alloc: whether need to do chunk pre-allocation, this is to * ensure we still have some free space after marking this * block group RO. */ int btrfs_inc_block_group_ro(struct btrfs_block_group *cache, bool do_chunk_alloc) { … } void btrfs_dec_block_group_ro(struct btrfs_block_group *cache) { … } static int update_block_group_item(struct btrfs_trans_handle *trans, struct btrfs_path *path, struct btrfs_block_group *cache) { … } static int cache_save_setup(struct btrfs_block_group *block_group, struct btrfs_trans_handle *trans, struct btrfs_path *path) { … } int btrfs_setup_space_cache(struct btrfs_trans_handle *trans) { … } /* * Transaction commit does final block group cache writeback during a critical * section where nothing is allowed to change the FS. This is required in * order for the cache to actually match the block group, but can introduce a * lot of latency into the commit. * * So, btrfs_start_dirty_block_groups is here to kick off block group cache IO. * There's a chance we'll have to redo some of it if the block group changes * again during the commit, but it greatly reduces the commit latency by * getting rid of the easy block groups while we're still allowing others to * join the commit. */ int btrfs_start_dirty_block_groups(struct btrfs_trans_handle *trans) { … } 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, bool alloc) { … } /* * Update the block_group and space info counters. * * @cache: The cache we are manipulating * @ram_bytes: The number of bytes of file content, and will be same to * @num_bytes except for the compress path. * @num_bytes: The number of bytes in question * @delalloc: The blocks are allocated for the delalloc write * * This is called by the allocator when it reserves space. If this is a * reservation and the block group has become read only we cannot make the * reservation and return -EAGAIN, otherwise this function always succeeds. */ int btrfs_add_reserved_bytes(struct btrfs_block_group *cache, u64 ram_bytes, u64 num_bytes, int delalloc, bool force_wrong_size_class) { … } /* * Update the block_group and space info counters. * * @cache: The cache we are manipulating * @num_bytes: The number of bytes in question * @delalloc: The blocks are allocated for the delalloc write * * This is called by somebody who is freeing space that was never actually used * on disk. For example if you reserve some space for a new leaf in transaction * A and before transaction A commits you free that leaf, you call this with * reserve set to 0 in order to clear the reservation. */ void btrfs_free_reserved_bytes(struct btrfs_block_group *cache, u64 num_bytes, int delalloc) { … } static void force_metadata_allocation(struct btrfs_fs_info *info) { … } static int should_alloc_chunk(struct btrfs_fs_info *fs_info, struct btrfs_space_info *sinfo, int force) { … } int btrfs_force_chunk_alloc(struct btrfs_trans_handle *trans, u64 type) { … } static struct btrfs_block_group *do_chunk_alloc(struct btrfs_trans_handle *trans, u64 flags) { … } /* * Chunk allocation is done in 2 phases: * * 1) Phase 1 - through btrfs_chunk_alloc() we allocate device extents for * the chunk, the chunk mapping, create its block group and add the items * that belong in the chunk btree to it - more specifically, we need to * update device items in the chunk btree and add a new chunk item to it. * * 2) Phase 2 - through btrfs_create_pending_block_groups(), we add the block * group item to the extent btree and the device extent items to the devices * btree. * * This is done to prevent deadlocks. For example when COWing a node from the * extent btree we are holding a write lock on the node's parent and if we * trigger chunk allocation and attempted to insert the new block group item * in the extent btree right way, we could deadlock because the path for the * insertion can include that parent node. At first glance it seems impossible * to trigger chunk allocation after starting a transaction since tasks should * reserve enough transaction units (metadata space), however while that is true * most of the time, chunk allocation may still be triggered for several reasons: * * 1) When reserving metadata, we check if there is enough free space in the * metadata space_info and therefore don't trigger allocation of a new chunk. * However later when the task actually tries to COW an extent buffer from * the extent btree or from the device btree for example, it is forced to * allocate a new block group (chunk) because the only one that had enough * free space was just turned to RO mode by a running scrub for example (or * device replace, block group reclaim thread, etc), so we can not use it * for allocating an extent and end up being forced to allocate a new one; * * 2) Because we only check that the metadata space_info has enough free bytes, * we end up not allocating a new metadata chunk in that case. However if * the filesystem was mounted in degraded mode, none of the existing block * groups might be suitable for extent allocation due to their incompatible * profile (for e.g. mounting a 2 devices filesystem, where all block groups * use a RAID1 profile, in degraded mode using a single device). In this case * when the task attempts to COW some extent buffer of the extent btree for * example, it will trigger allocation of a new metadata block group with a * suitable profile (SINGLE profile in the example of the degraded mount of * the RAID1 filesystem); * * 3) The task has reserved enough transaction units / metadata space, but when * it attempts to COW an extent buffer from the extent or device btree for * example, it does not find any free extent in any metadata block group, * therefore forced to try to allocate a new metadata block group. * This is because some other task allocated all available extents in the * meanwhile - this typically happens with tasks that don't reserve space * 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; * * 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 * any of the block group items to the chunk, extent and device btrees. If we * did not do it this way, we would get ENOSPC when attempting to update those * btrees, since all the chunks from the seed device are read-only. * * Phase 1 does the updates and insertions to the chunk btree because if we had * it done in phase 2 and have a thundering herd of tasks allocating chunks in * parallel, we risk having too many system chunks allocated by many tasks if * many tasks reach phase 1 without the previous ones completing phase 2. In the * extreme case this leads to exhaustion of the system chunk array in the * superblock. This is easier to trigger if using a btree node/leaf size of 64K * and with RAID filesystems (so we have more device items in the chunk btree). * This has happened before and commit eafa4fd0ad0607 ("btrfs: fix exhaustion of * the system chunk array due to concurrent allocations") provides more details. * * 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 * holding fs_info->chunk_mutex. This is important to guarantee that while COWing * an extent buffer from the chunks btree we never trigger allocation of a new * system chunk, which would result in a deadlock (trying to lock twice an * extent buffer of the chunk btree, first time before triggering the chunk * allocation and the second time during chunk allocation while attempting to * update the chunks btree). The system chunk array is also updated while holding * that mutex. The same logic applies to removing chunks - we must reserve system * space, update the chunk btree and the system chunk array in the superblock * while holding fs_info->chunk_mutex. * * This function, btrfs_chunk_alloc(), belongs to phase 1. * * If @force is CHUNK_ALLOC_FORCE: * - return 1 if it successfully allocates a chunk, * - return errors including -ENOSPC otherwise. * If @force is NOT CHUNK_ALLOC_FORCE: * - return 0 if it doesn't need to allocate a new chunk, * - return 1 if it successfully allocates a chunk, * - return errors including -ENOSPC otherwise. */ int btrfs_chunk_alloc(struct btrfs_trans_handle *trans, u64 flags, enum btrfs_chunk_alloc_enum force) { … } static u64 get_profile_num_devs(struct btrfs_fs_info *fs_info, u64 type) { … } static void reserve_chunk_space(struct btrfs_trans_handle *trans, u64 bytes, u64 type) { … } /* * 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) { … } /* * 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) { … } void btrfs_put_block_group_cache(struct btrfs_fs_info *info) { … } /* * Must be called only after stopping all workers, since we could have block * group caching kthreads running, and therefore they could race with us if we * freed the block groups before stopping them. */ int btrfs_free_block_groups(struct btrfs_fs_info *info) { … } void btrfs_freeze_block_group(struct btrfs_block_group *cache) { … } void btrfs_unfreeze_block_group(struct btrfs_block_group *block_group) { … } bool btrfs_inc_block_group_swap_extents(struct btrfs_block_group *bg) { … } void btrfs_dec_block_group_swap_extents(struct btrfs_block_group *bg, int amount) { … } enum btrfs_block_group_size_class btrfs_calc_block_group_size_class(u64 size) { … } /* * Handle a block group allocating an extent in a size class * * @bg: The block group we allocated in. * @size_class: The size class of the allocation. * @force_wrong_size_class: Whether we are desperate enough to allow * mismatched size classes. * * Returns: 0 if the size class was valid for this block_group, -EAGAIN in the * case of a race that leads to the wrong size class without * force_wrong_size_class set. * * find_free_extent will skip block groups with a mismatched size class until * it really needs to avoid ENOSPC. In that case it will set * force_wrong_size_class. However, if a block group is newly allocated and * doesn't yet have a size class, then it is possible for two allocations of * different sizes to race and both try to use it. The loser is caught here and * has to retry. */ int btrfs_use_block_group_size_class(struct btrfs_block_group *bg, enum btrfs_block_group_size_class size_class, bool force_wrong_size_class) { … } bool btrfs_block_group_should_use_size_class(struct btrfs_block_group *bg) { … }
Codebase Browser
linux