Btrfs: account for space used by the super mirrors

As we get closer to proper -ENOSPC handling in btrfs, we need more accurate
space accounting for the space info's.  Currently we exclude the free space for
the super mirrors, but the space they take up isn't accounted for in any of the
counters.  This patch introduces bytes_super, which keeps track of the amount
of bytes used for a super mirror in the block group cache and space info.  This
makes sure that our free space caclucations will be completely accurate.

Signed-off-by: Josef Bacik <jbacik@redhat.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 2b15fb97d23fc7cd22cfabd6af7c6d1d72964b3b..80599b4e42bd350f5e6b7a094c3711a3dd32e8a8 100644 (file)
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -674,6 +674,7 @@ struct btrfs_space_info {
        u64 bytes_reserved;     /* total bytes the allocator has reserved for
                                   current allocations */
        u64 bytes_readonly;     /* total bytes that are read only */
+       u64 bytes_super;        /* total bytes reserved for the super blocks */
 
        /* delalloc accounting */
        u64 bytes_delalloc;     /* number of bytes reserved for allocation,
@@ -746,6 +747,7 @@ struct btrfs_block_group_cache {
        spinlock_t lock;
        u64 pinned;
        u64 reserved;
+       u64 bytes_super;
        u64 flags;
        u64 sectorsize;
        int extents_thresh;

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 93e376ada28b5bd457761a2f0f4a7528e21a2ed2..5f3544e5f3cb1179ba70dc3fc2077c65f940f0cb 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -201,6 +201,7 @@ static int exclude_super_stripes(struct btrfs_root *root,
                BUG_ON(ret);
 
                while (nr--) {
+                       cache->bytes_super += stripe_len;
                        ret = add_excluded_extent(root, logical[nr],
                                                  stripe_len);
                        BUG_ON(ret);
@@ -295,6 +296,9 @@ static int caching_kthread(void *data)
                return -ENOMEM;
 
        exclude_super_stripes(extent_root, block_group);
+       spin_lock(&block_group->space_info->lock);
+       block_group->space_info->bytes_super += block_group->bytes_super;
+       spin_unlock(&block_group->space_info->lock);
 
        last = max_t(u64, block_group->key.objectid, BTRFS_SUPER_INFO_OFFSET);
 
@@ -2785,7 +2789,8 @@ again:
        do_div(thresh, 100);
 
        if (meta_sinfo->bytes_used + meta_sinfo->bytes_reserved +
-           meta_sinfo->bytes_pinned + meta_sinfo->bytes_readonly > thresh) {
+           meta_sinfo->bytes_pinned + meta_sinfo->bytes_readonly +
+           meta_sinfo->bytes_super > thresh) {
                struct btrfs_trans_handle *trans;
                if (!meta_sinfo->full) {
                        meta_sinfo->force_alloc = 1;
@@ -2839,7 +2844,7 @@ again:
        if (data_sinfo->total_bytes - data_sinfo->bytes_used -
            data_sinfo->bytes_delalloc - data_sinfo->bytes_reserved -
            data_sinfo->bytes_pinned - data_sinfo->bytes_readonly -
-           data_sinfo->bytes_may_use < bytes) {
+           data_sinfo->bytes_may_use - data_sinfo->bytes_super < bytes) {
                struct btrfs_trans_handle *trans;
 
                /*
@@ -6957,8 +6962,10 @@ int btrfs_read_block_groups(struct btrfs_root *root)
                 * time, particularly in the full case.
                 */
                if (found_key.offset == btrfs_block_group_used(&cache->item)) {
+                       exclude_super_stripes(root, cache);
                        cache->last_byte_to_unpin = (u64)-1;
                        cache->cached = BTRFS_CACHE_FINISHED;
+                       free_excluded_extents(root, cache);
                } else if (btrfs_block_group_used(&cache->item) == 0) {
                        exclude_super_stripes(root, cache);
                        cache->last_byte_to_unpin = (u64)-1;
@@ -6975,6 +6982,10 @@ int btrfs_read_block_groups(struct btrfs_root *root)
                                        &space_info);
                BUG_ON(ret);
                cache->space_info = space_info;
+               spin_lock(&cache->space_info->lock);
+               cache->space_info->bytes_super += cache->bytes_super;
+               spin_unlock(&cache->space_info->lock);
+
                down_write(&space_info->groups_sem);
                list_add_tail(&cache->list, &space_info->block_groups);
                up_write(&space_info->groups_sem);
@@ -7044,6 +7055,11 @@ int btrfs_make_block_group(struct btrfs_trans_handle *trans,
        ret = update_space_info(root->fs_info, cache->flags, size, bytes_used,
                                &cache->space_info);
        BUG_ON(ret);
+
+       spin_lock(&cache->space_info->lock);
+       cache->space_info->bytes_super += cache->bytes_super;
+       spin_unlock(&cache->space_info->lock);
+
        down_write(&cache->space_info->groups_sem);
        list_add_tail(&cache->list, &cache->space_info->block_groups);
        up_write(&cache->space_info->groups_sem);