diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index d33780082b8d..329a922893b4 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -1509,30 +1509,158 @@ struct btrfs_device *btrfs_scan_one_device(const char *path, } /* - * Try to find a chunk that intersects [start, start + len] range and when one - * such is found, record the end of it in *start + * Find the first pending extent intersecting a range. + * + * @device: the device to search + * @start: start of the range to check + * @len: length of the range to check + * @pending_start: output pointer for the start of the found pending extent + * @pending_end: output pointer for the end of the found pending extent (inclusive) + * + * Search for a pending chunk allocation that intersects the half-open range + * [start, start + len). + * + * Return: true if a pending extent was found, false otherwise. + * If the return value is true, store the first pending extent in + * [*pending_start, *pending_end]. Otherwise, the two output variables + * may still be modified, to something outside the range and should not + * be used. */ -static bool contains_pending_extent(struct btrfs_device *device, u64 *start, - u64 len) +static bool first_pending_extent(struct btrfs_device *device, u64 start, u64 len, + u64 *pending_start, u64 *pending_end) { - u64 physical_start, physical_end; - lockdep_assert_held(&device->fs_info->chunk_mutex); - if (btrfs_find_first_extent_bit(&device->alloc_state, *start, - &physical_start, &physical_end, + if (btrfs_find_first_extent_bit(&device->alloc_state, start, + pending_start, pending_end, CHUNK_ALLOCATED, NULL)) { - if (in_range(physical_start, *start, len) || - in_range(*start, physical_start, - physical_end + 1 - physical_start)) { - *start = physical_end + 1; + if (in_range(*pending_start, start, len) || + in_range(start, *pending_start, *pending_end + 1 - *pending_start)) { return true; } } return false; } +/* + * Find the first real hole accounting for pending extents. + * + * @device: the device containing the candidate hole + * @start: input/output pointer for the hole start position + * @len: input/output pointer for the hole length + * @min_hole_size: the size of hole we are looking for + * + * Given a potential hole specified by [*start, *start + *len), check for pending + * chunk allocations within that range. If pending extents are found, the hole is + * adjusted to represent the first true free space that is large enough when + * accounting for pending chunks. + * + * Note that this function must handle various cases involving non consecutive + * pending extents. + * + * Returns: true if a suitable hole was found and false otherwise. + * If the return value is true, then *start and *len are set to represent the hole. + * If the return value is false, then *start is set to the largest hole we + * found and *len is set to its length. + * If there are no holes at all, then *start is set to the end of the range and + * *len is set to 0. + */ +static bool find_hole_in_pending_extents(struct btrfs_device *device, u64 *start, + u64 *len, u64 min_hole_size) +{ + u64 pending_start, pending_end; + u64 end; + u64 max_hole_start = 0; + u64 max_hole_len = 0; + + lockdep_assert_held(&device->fs_info->chunk_mutex); + + if (*len == 0) + return false; + + end = *start + *len - 1; + + /* + * Loop until we either see a large enough hole or check every pending + * extent overlapping the candidate hole. + * At every hole that we observe, record it if it is the new max. + * At the end of the iteration, set the output variables to the max hole. + */ + while (true) { + if (first_pending_extent(device, *start, *len, &pending_start, &pending_end)) { + /* + * Case 1: the pending extent overlaps the start of + * candidate hole. That means the true hole is after the + * pending extent, but we need to find the next pending + * extent to properly size the hole. In the next loop, + * we will reduce to case 2 or 3. + * e.g., + * + * |----pending A----| real hole |----pending B----| + * | candidate hole | + * *start end + */ + if (pending_start <= *start) { + *start = pending_end + 1; + goto next; + } + /* + * Case 2: The pending extent starts after *start (and overlaps + * [*start, end), so the first hole just goes up to the start + * of the pending extent. + * e.g., + * + * | real hole |----pending A----| + * | candidate hole | + * *start end + */ + *len = pending_start - *start; + if (*len > max_hole_len) { + max_hole_start = *start; + max_hole_len = *len; + } + if (*len >= min_hole_size) + break; + /* + * If the hole wasn't big enough, then we advance past + * the pending extent and keep looking. + */ + *start = pending_end + 1; + goto next; + } else { + /* + * Case 3: There is no pending extent overlapping the + * range [*start, *start + *len - 1], so the only remaining + * hole is the remaining range. + * e.g., + * + * | candidate hole | + * | real hole | + * *start end + */ + + if (*len > max_hole_len) { + max_hole_start = *start; + max_hole_len = *len; + } + break; + } +next: + if (*start > end) + break; + *len = end - *start + 1; + } + if (max_hole_len) { + *start = max_hole_start; + *len = max_hole_len; + } else { + *start = end + 1; + *len = 0; + } + return max_hole_len >= min_hole_size; +} + static u64 dev_extent_search_start(struct btrfs_device *device) { switch (device->fs_devices->chunk_alloc_policy) { @@ -1597,59 +1725,57 @@ static bool dev_extent_hole_check_zoned(struct btrfs_device *device, } /* - * Check if specified hole is suitable for allocation. + * Validate and adjust a hole for chunk allocation * - * @device: the device which we have the hole - * @hole_start: starting position of the hole - * @hole_size: the size of the hole - * @num_bytes: the size of the free space that we need + * @device: the device containing the candidate hole + * @hole_start: input/output pointer for the hole start position + * @hole_size: input/output pointer for the hole size + * @num_bytes: minimum allocation size required * - * This function may modify @hole_start and @hole_size to reflect the suitable - * position for allocation. Returns 1 if hole position is updated, 0 otherwise. + * Check if the specified hole is suitable for allocation and adjust it if + * necessary. The hole may be modified to skip over pending chunk allocations + * and to satisfy stricter zoned requirements on zoned filesystems. + * + * For regular (non-zoned) allocation, if the hole after adjustment is smaller + * than @num_bytes, the search continues past additional pending extents until + * either a sufficiently large hole is found or no more pending extents exist. + * + * Return: true if a suitable hole was found and false otherwise. + * If the return value is true, then *hole_start and *hole_size are set to + * represent the hole we found. + * If the return value is false, then *hole_start is set to the largest + * hole we found and *hole_size is set to its length. + * If there are no holes at all, then *hole_start is set to the end of the range + * and *hole_size is set to 0. */ static bool dev_extent_hole_check(struct btrfs_device *device, u64 *hole_start, u64 *hole_size, u64 num_bytes) { - bool changed = false; - u64 hole_end = *hole_start + *hole_size; + bool found = false; + const u64 hole_end = *hole_start + *hole_size - 1; - for (;;) { - /* - * Check before we set max_hole_start, otherwise we could end up - * sending back this offset anyway. - */ - if (contains_pending_extent(device, hole_start, *hole_size)) { - if (hole_end >= *hole_start) - *hole_size = hole_end - *hole_start; - else - *hole_size = 0; - changed = true; - } + ASSERT(*hole_size > 0); - switch (device->fs_devices->chunk_alloc_policy) { - default: - btrfs_warn_unknown_chunk_allocation(device->fs_devices->chunk_alloc_policy); - fallthrough; - case BTRFS_CHUNK_ALLOC_REGULAR: - /* No extra check */ - break; - case BTRFS_CHUNK_ALLOC_ZONED: - if (dev_extent_hole_check_zoned(device, hole_start, - hole_size, num_bytes)) { - changed = true; - /* - * The changed hole can contain pending extent. - * Loop again to check that. - */ - continue; - } - break; - } +again: + *hole_size = hole_end - *hole_start + 1; + found = find_hole_in_pending_extents(device, hole_start, hole_size, num_bytes); + if (!found) + return found; + ASSERT(*hole_size >= num_bytes); + switch (device->fs_devices->chunk_alloc_policy) { + default: + btrfs_warn_unknown_chunk_allocation(device->fs_devices->chunk_alloc_policy); + fallthrough; + case BTRFS_CHUNK_ALLOC_REGULAR: + return found; + case BTRFS_CHUNK_ALLOC_ZONED: + if (dev_extent_hole_check_zoned(device, hole_start, hole_size, num_bytes)) + goto again; break; } - return changed; + return found; } /* @@ -1708,7 +1834,7 @@ static int find_free_dev_extent(struct btrfs_device *device, u64 num_bytes, ret = -ENOMEM; goto out; } -again: + if (search_start >= search_end || test_bit(BTRFS_DEV_STATE_REPLACE_TGT, &device->dev_state)) { ret = -ENOSPC; @@ -1795,11 +1921,7 @@ static int find_free_dev_extent(struct btrfs_device *device, u64 num_bytes, */ if (search_end > search_start) { hole_size = search_end - search_start; - if (dev_extent_hole_check(device, &search_start, &hole_size, - num_bytes)) { - btrfs_release_path(path); - goto again; - } + dev_extent_hole_check(device, &search_start, &hole_size, num_bytes); if (hole_size > max_hole_size) { max_hole_start = search_start; @@ -5022,6 +5144,7 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size) u64 diff; u64 start; u64 free_diff = 0; + u64 pending_start, pending_end; new_size = round_down(new_size, fs_info->sectorsize); start = new_size; @@ -5067,7 +5190,7 @@ int btrfs_shrink_device(struct btrfs_device *device, u64 new_size) * in-memory chunks are synced to disk so that the loop below sees them * and relocates them accordingly. */ - if (contains_pending_extent(device, &start, diff)) { + if (first_pending_extent(device, start, diff, &pending_start, &pending_end)) { mutex_unlock(&fs_info->chunk_mutex); ret = btrfs_commit_transaction(trans); if (ret)