Btrfs: improve the noflush reservation

In some places(such as: evicting inode), we just can not flush the reserved
space of delalloc, flushing the delayed directory index and delayed inode
is OK, but we don't try to flush those things and just go back when there is
no enough space to be reserved. This patch fixes this problem.

We defined 3 types of the flush operations: NO_FLUSH, FLUSH_LIMIT and FLUSH_ALL.
If we can in the transaction, we should not flush anything, or the deadlock
would happen, so use NO_FLUSH. If we flushing the reserved space of delalloc
would cause deadlock, use FLUSH_LIMIT. In the other cases, FLUSH_ALL is used,
and we will flush all things.

Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

1 files changed, 16 insertions, 10 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index c72ead869507..8fd9fe4282f5 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2900,6 +2900,18 @@ void btrfs_create_pending_block_groups(struct btrfs_trans_handle *trans,
 u64 btrfs_reduce_alloc_profile(struct btrfs_root *root, u64 flags);
 u64 btrfs_get_alloc_profile(struct btrfs_root *root, int data);
 void btrfs_clear_space_info_full(struct btrfs_fs_info *info);
+
+enum btrfs_reserve_flush_enum {
+        /* If we are in the transaction, we can't flush anything.*/
+        BTRFS_RESERVE_NO_FLUSH,
+        /*
+         * Flushing delalloc may cause deadlock somewhere, in this
+         * case, use FLUSH LIMIT
+         */
+        BTRFS_RESERVE_FLUSH_LIMIT,
+        BTRFS_RESERVE_FLUSH_ALL,
+};
+
 int btrfs_check_data_free_space(struct inode *inode, u64 bytes);
 void btrfs_free_reserved_data_space(struct inode *inode, u64 bytes);
 void btrfs_trans_release_metadata(struct btrfs_trans_handle *trans,
@@ -2919,19 +2931,13 @@ struct btrfs_block_rsv *btrfs_alloc_block_rsv(struct btrfs_root *root,
 void btrfs_free_block_rsv(struct btrfs_root *root,
                           struct btrfs_block_rsv *rsv);
 int btrfs_block_rsv_add(struct btrfs_root *root,
-                        struct btrfs_block_rsv *block_rsv,
-                        u64 num_bytes);
-int btrfs_block_rsv_add_noflush(struct btrfs_root *root,
-                                struct btrfs_block_rsv *block_rsv,
-                                u64 num_bytes);
+                        struct btrfs_block_rsv *block_rsv, u64 num_bytes,
+                        enum btrfs_reserve_flush_enum flush);
 int btrfs_block_rsv_check(struct btrfs_root *root,
                           struct btrfs_block_rsv *block_rsv, int min_factor);
 int btrfs_block_rsv_refill(struct btrfs_root *root,
-                          struct btrfs_block_rsv *block_rsv,
-                          u64 min_reserved);
-int btrfs_block_rsv_refill_noflush(struct btrfs_root *root,
-                                   struct btrfs_block_rsv *block_rsv,
-                                   u64 min_reserved);
+                           struct btrfs_block_rsv *block_rsv, u64 min_reserved,
+                           enum btrfs_reserve_flush_enum flush);
 int btrfs_block_rsv_migrate(struct btrfs_block_rsv *src_rsv,
                             struct btrfs_block_rsv *dst_rsv,
                             u64 num_bytes);