Btrfs: add better -ENOSPC handling

This is a step in the direction of better -ENOSPC handling.  Instead of
checking the global bytes counter we check the space_info bytes counters to
make sure we have enough space.

If we don't we go ahead and try to allocate a new chunk, and then if that fails
we return -ENOSPC.  This patch adds two counters to btrfs_space_info,
bytes_delalloc and bytes_may_use.

bytes_delalloc account for extents we've actually setup for delalloc and will
be allocated at some point down the line. 

bytes_may_use is to keep track of how many bytes we may use for delalloc at
some point.  When we actually set the extent_bit for the delalloc bytes we
subtract the reserved bytes from the bytes_may_use counter.  This keeps us from
not actually being able to allocate space for any delalloc bytes.

Signed-off-by: Josef Bacik <jbacik@redhat.com>

1 files changed, 16 insertions, 46 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 3cee77ae03c8..7d4f948bc22a 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -102,34 +102,6 @@ static int btrfs_init_inode_security(struct inode *inode,  struct inode *dir)
 }
 
 /*
- * a very lame attempt at stopping writes when the FS is 85% full.  There
- * are countless ways this is incorrect, but it is better than nothing.
- */
-int btrfs_check_free_space(struct btrfs_root *root, u64 num_required,
-                           int for_del)
-{
-        u64 total;
-        u64 used;
-        u64 thresh;
-        int ret = 0;
-
-        spin_lock(&root->fs_info->delalloc_lock);
-        total = btrfs_super_total_bytes(&root->fs_info->super_copy);
-        used = btrfs_super_bytes_used(&root->fs_info->super_copy);
-        if (for_del)
-                thresh = total * 90;
-        else
-                thresh = total * 85;
-
-        do_div(thresh, 100);
-
-        if (used + root->fs_info->delalloc_bytes + num_required > thresh)
-                ret = -ENOSPC;
-        spin_unlock(&root->fs_info->delalloc_lock);
-        return ret;
-}
-
-/*
  * this does all the hard work for inserting an inline extent into
  * the btree.  The caller should have done a btrfs_drop_extents so that
  * no overlapping inline items exist in the btree
@@ -1190,6 +1162,7 @@ static int btrfs_set_bit_hook(struct inode *inode, u64 start, u64 end,
          */
         if (!(old & EXTENT_DELALLOC) && (bits & EXTENT_DELALLOC)) {
                 struct btrfs_root *root = BTRFS_I(inode)->root;
+                btrfs_delalloc_reserve_space(root, inode, end - start + 1);
                 spin_lock(&root->fs_info->delalloc_lock);
                 BTRFS_I(inode)->delalloc_bytes += end - start + 1;
                 root->fs_info->delalloc_bytes += end - start + 1;
@@ -1223,9 +1196,12 @@ static int btrfs_clear_bit_hook(struct inode *inode, u64 start, u64 end,
                                (unsigned long long)end - start + 1,
                                (unsigned long long)
                                root->fs_info->delalloc_bytes);
+                        btrfs_delalloc_free_space(root, inode, (u64)-1);
                         root->fs_info->delalloc_bytes = 0;
                         BTRFS_I(inode)->delalloc_bytes = 0;
                 } else {
+                        btrfs_delalloc_free_space(root, inode,
+                                                  end - start + 1);
                         root->fs_info->delalloc_bytes -= end - start + 1;
                         BTRFS_I(inode)->delalloc_bytes -= end - start + 1;
                 }
@@ -2245,10 +2221,6 @@ static int btrfs_unlink(struct inode *dir, struct dentry *dentry)
 
         root = BTRFS_I(dir)->root;
 
-        ret = btrfs_check_free_space(root, 1, 1);
-        if (ret)
-                goto fail;
-
         trans = btrfs_start_transaction(root, 1);
 
         btrfs_set_trans_block_group(trans, dir);
@@ -2261,7 +2233,6 @@ static int btrfs_unlink(struct inode *dir, struct dentry *dentry)
         nr = trans->blocks_used;
 
         btrfs_end_transaction_throttle(trans, root);
-fail:
         btrfs_btree_balance_dirty(root, nr);
         return ret;
 }
@@ -2284,10 +2255,6 @@ static int btrfs_rmdir(struct inode *dir, struct dentry *dentry)
                 return -ENOTEMPTY;
         }
 
-        ret = btrfs_check_free_space(root, 1, 1);
-        if (ret)
-                goto fail;
-
         trans = btrfs_start_transaction(root, 1);
         btrfs_set_trans_block_group(trans, dir);
 
@@ -2304,7 +2271,6 @@ static int btrfs_rmdir(struct inode *dir, struct dentry *dentry)
 fail_trans:
         nr = trans->blocks_used;
         ret = btrfs_end_transaction_throttle(trans, root);
-fail:
         btrfs_btree_balance_dirty(root, nr);
 
         if (ret && !err)
@@ -2818,7 +2784,7 @@ int btrfs_cont_expand(struct inode *inode, loff_t size)
         if (size <= hole_start)
                 return 0;
 
-        err = btrfs_check_free_space(root, 1, 0);
+        err = btrfs_check_metadata_free_space(root);
         if (err)
                 return err;
 
@@ -3014,6 +2980,7 @@ static noinline void init_btrfs_i(struct inode *inode)
         bi->last_trans = 0;
         bi->logged_trans = 0;
         bi->delalloc_bytes = 0;
+        bi->reserved_bytes = 0;
         bi->disk_i_size = 0;
         bi->flags = 0;
         bi->index_cnt = (u64)-1;
@@ -3035,6 +3002,7 @@ static int btrfs_init_locked_inode(struct inode *inode, void *p)
         inode->i_ino = args->ino;
         init_btrfs_i(inode);
         BTRFS_I(inode)->root = args->root;
+        btrfs_set_inode_space_info(args->root, inode);
         return 0;
 }
 
@@ -3455,6 +3423,7 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
         BTRFS_I(inode)->index_cnt = 2;
         BTRFS_I(inode)->root = root;
         BTRFS_I(inode)->generation = trans->transid;
+        btrfs_set_inode_space_info(root, inode);
 
         if (mode & S_IFDIR)
                 owner = 0;
@@ -3602,7 +3571,7 @@ static int btrfs_mknod(struct inode *dir, struct dentry *dentry,
         if (!new_valid_dev(rdev))
                 return -EINVAL;
 
-        err = btrfs_check_free_space(root, 1, 0);
+        err = btrfs_check_metadata_free_space(root);
         if (err)
                 goto fail;
 
@@ -3665,7 +3634,7 @@ static int btrfs_create(struct inode *dir, struct dentry *dentry,
         u64 objectid;
         u64 index = 0;
 
-        err = btrfs_check_free_space(root, 1, 0);
+        err = btrfs_check_metadata_free_space(root);
         if (err)
                 goto fail;
         trans = btrfs_start_transaction(root, 1);
@@ -3733,7 +3702,7 @@ static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
                 return -ENOENT;
 
         btrfs_inc_nlink(inode);
-        err = btrfs_check_free_space(root, 1, 0);
+        err = btrfs_check_metadata_free_space(root);
         if (err)
                 goto fail;
         err = btrfs_set_inode_index(dir, &index);
@@ -3779,7 +3748,7 @@ static int btrfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
         u64 index = 0;
         unsigned long nr = 1;
 
-        err = btrfs_check_free_space(root, 1, 0);
+        err = btrfs_check_metadata_free_space(root);
         if (err)
                 goto out_unlock;
 
@@ -4336,7 +4305,7 @@ int btrfs_page_mkwrite(struct vm_area_struct *vma, struct page *page)
         u64 page_start;
         u64 page_end;
 
-        ret = btrfs_check_free_space(root, PAGE_CACHE_SIZE, 0);
+        ret = btrfs_check_data_free_space(root, inode, PAGE_CACHE_SIZE);
         if (ret)
                 goto out;
 
@@ -4349,6 +4318,7 @@ again:
 
         if ((page->mapping != inode->i_mapping) ||
             (page_start >= size)) {
+                btrfs_free_reserved_data_space(root, inode, PAGE_CACHE_SIZE);
                 /* page got truncated out from underneath us */
                 goto out_unlock;
         }
@@ -4631,7 +4601,7 @@ static int btrfs_rename(struct inode *old_dir, struct dentry *old_dentry,
         if (old_inode->i_ino == BTRFS_FIRST_FREE_OBJECTID)
                 return -EXDEV;
 
-        ret = btrfs_check_free_space(root, 1, 0);
+        ret = btrfs_check_metadata_free_space(root);
         if (ret)
                 goto out_unlock;
 
@@ -4749,7 +4719,7 @@ static int btrfs_symlink(struct inode *dir, struct dentry *dentry,
         if (name_len > BTRFS_MAX_INLINE_DATA_SIZE(root))
                 return -ENAMETOOLONG;
 
-        err = btrfs_check_free_space(root, 1, 0);
+        err = btrfs_check_metadata_free_space(root);
         if (err)
                 goto out_fail;