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, 31 insertions, 9 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 766b31ae3186..82491ba8fa40 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -596,13 +596,27 @@ struct btrfs_block_group_item {
 
 struct btrfs_space_info {
         u64 flags;
-        u64 total_bytes;
-        u64 bytes_used;
-        u64 bytes_pinned;
-        u64 bytes_reserved;
-        u64 bytes_readonly;
-        int full;
-        int force_alloc;
+
+        u64 total_bytes;        /* total bytes in the space */
+        u64 bytes_used;         /* total bytes used on disk */
+        u64 bytes_pinned;       /* total bytes pinned, will be freed when the
+                                   transaction finishes */
+        u64 bytes_reserved;     /* total bytes the allocator has reserved for
+                                   current allocations */
+        u64 bytes_readonly;     /* total bytes that are read only */
+
+        /* delalloc accounting */
+        u64 bytes_delalloc;     /* number of bytes reserved for allocation,
+                                   this space is not necessarily reserved yet
+                                   by the allocator */
+        u64 bytes_may_use;      /* number of bytes that may be used for
+                                   delalloc */
+
+        int full;               /* indicates that we cannot allocate any more
+                                   chunks for this space */
+        int force_alloc;        /* set if we need to force a chunk alloc for
+                                   this space */
+
         struct list_head list;
 
         /* for block groups in our same type */
@@ -1782,6 +1796,16 @@ int btrfs_add_dead_reloc_root(struct btrfs_root *root);
 int btrfs_cleanup_reloc_trees(struct btrfs_root *root);
 int btrfs_reloc_clone_csums(struct inode *inode, u64 file_pos, u64 len);
 u64 btrfs_reduce_alloc_profile(struct btrfs_root *root, u64 flags);
+void btrfs_set_inode_space_info(struct btrfs_root *root, struct inode *ionde);
+int btrfs_check_metadata_free_space(struct btrfs_root *root);
+int btrfs_check_data_free_space(struct btrfs_root *root, struct inode *inode,
+                                u64 bytes);
+void btrfs_free_reserved_data_space(struct btrfs_root *root,
+                                    struct inode *inode, u64 bytes);
+void btrfs_delalloc_reserve_space(struct btrfs_root *root, struct inode *inode,
+                                 u64 bytes);
+void btrfs_delalloc_free_space(struct btrfs_root *root, struct inode *inode,
+                              u64 bytes);
 /* ctree.c */
 int btrfs_previous_item(struct btrfs_root *root,
                         struct btrfs_path *path, u64 min_objectid,
@@ -2027,8 +2051,6 @@ int btrfs_merge_bio_hook(struct page *page, unsigned long offset,
 unsigned long btrfs_force_ra(struct address_space *mapping,
                               struct file_ra_state *ra, struct file *file,
                               pgoff_t offset, pgoff_t last_index);
-int btrfs_check_free_space(struct btrfs_root *root, u64 num_required,
-                           int for_del);
 int btrfs_page_mkwrite(struct vm_area_struct *vma, struct page *page);
 int btrfs_readpage(struct file *file, struct page *page);
 void btrfs_delete_inode(struct inode *inode);