From 3eeb3226a8891544ea4a9baf27ba3d73e8a42991 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Thu, 20 Jun 2019 15:37:47 -0400 Subject: btrfs: migrate nocow and reservation helpers These are relatively straightforward as well. Signed-off-by: Josef Bacik Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/block-group.c | 82 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 82 insertions(+) (limited to 'fs/btrfs/block-group.c') diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c index 4328196a4d44..1f3afa0b42ba 100644 --- a/fs/btrfs/block-group.c +++ b/fs/btrfs/block-group.c @@ -2,6 +2,7 @@ #include "ctree.h" #include "block-group.h" +#include "space-info.h" void btrfs_get_block_group(struct btrfs_block_group_cache *cache) { @@ -118,3 +119,84 @@ struct btrfs_block_group_cache *btrfs_next_block_group( spin_unlock(&fs_info->block_group_cache_lock); return cache; } + +bool btrfs_inc_nocow_writers(struct btrfs_fs_info *fs_info, u64 bytenr) +{ + struct btrfs_block_group_cache *bg; + bool ret = true; + + bg = btrfs_lookup_block_group(fs_info, bytenr); + if (!bg) + return false; + + spin_lock(&bg->lock); + if (bg->ro) + ret = false; + else + atomic_inc(&bg->nocow_writers); + spin_unlock(&bg->lock); + + /* No put on block group, done by btrfs_dec_nocow_writers */ + if (!ret) + btrfs_put_block_group(bg); + + return ret; +} + +void btrfs_dec_nocow_writers(struct btrfs_fs_info *fs_info, u64 bytenr) +{ + struct btrfs_block_group_cache *bg; + + bg = btrfs_lookup_block_group(fs_info, bytenr); + ASSERT(bg); + if (atomic_dec_and_test(&bg->nocow_writers)) + wake_up_var(&bg->nocow_writers); + /* + * Once for our lookup and once for the lookup done by a previous call + * to btrfs_inc_nocow_writers() + */ + btrfs_put_block_group(bg); + btrfs_put_block_group(bg); +} + +void btrfs_wait_nocow_writers(struct btrfs_block_group_cache *bg) +{ + wait_var_event(&bg->nocow_writers, !atomic_read(&bg->nocow_writers)); +} + +void btrfs_dec_block_group_reservations(struct btrfs_fs_info *fs_info, + const u64 start) +{ + struct btrfs_block_group_cache *bg; + + bg = btrfs_lookup_block_group(fs_info, start); + ASSERT(bg); + if (atomic_dec_and_test(&bg->reservations)) + wake_up_var(&bg->reservations); + btrfs_put_block_group(bg); +} + +void btrfs_wait_block_group_reservations(struct btrfs_block_group_cache *bg) +{ + struct btrfs_space_info *space_info = bg->space_info; + + ASSERT(bg->ro); + + if (!(bg->flags & BTRFS_BLOCK_GROUP_DATA)) + return; + + /* + * Our block group is read only but before we set it to read only, + * some task might have had allocated an extent from it already, but it + * has not yet created a respective ordered extent (and added it to a + * root's list of ordered extents). + * Therefore wait for any task currently allocating extents, since the + * block group's reservations counter is incremented while a read lock + * on the groups' semaphore is held and decremented after releasing + * the read access on that semaphore and creating the ordered extent. + */ + down_write(&space_info->groups_sem); + up_write(&space_info->groups_sem); + + wait_var_event(&bg->reservations, !atomic_read(&bg->reservations)); +} -- cgit v1.2.3