ext4: add flag to ext4_has_free_blocks

This patch adds an allocation request flag to the ext4_has_free_blocks
function which enables the use of reserved blocks.  This will allow a
punch hole to proceed even if the disk is full.  Punching a hole may
require additional blocks to first split the extents.

Because ext4_has_free_blocks is a low level function, the flag needs
to be passed down through several functions listed below:

ext4_ext_insert_extent
ext4_ext_create_new_leaf
ext4_ext_grow_indepth
ext4_ext_split
ext4_ext_new_meta_block
ext4_mb_new_blocks
ext4_claim_free_blocks
ext4_has_free_blocks

[ext4 punch hole patch series 1/5 v7]

Signed-off-by: Allison Henderson <achender@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Mingming Cao <cmm@us.ibm.com>
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 2bc4c21..2f310d1 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -108,7 +108,8 @@
 #define EXT4_MB_DELALLOC_RESERVED	0x0400
 /* We are doing stream allocation */
 #define EXT4_MB_STREAM_ALLOC		0x0800
-
+/* Use reserved root blocks if needed */
+#define EXT4_MB_USE_ROOT_BLOCKS		0x1000
 
 struct ext4_allocation_request {
 	/* target inode for block we're allocating */
@@ -514,6 +515,8 @@
 	/* Convert extent to initialized after IO complete */
 #define EXT4_GET_BLOCKS_IO_CONVERT_EXT		(EXT4_GET_BLOCKS_CONVERT|\
 					 EXT4_GET_BLOCKS_CREATE_UNINIT_EXT)
+	/* Punch out blocks of an extent */
+#define EXT4_GET_BLOCKS_PUNCH_OUT_EXT		0x0020
 
 /*
  * Flags used by ext4_free_blocks
@@ -1718,8 +1721,12 @@
 extern unsigned long ext4_bg_num_gdb(struct super_block *sb,
 			ext4_group_t group);
 extern ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
-			ext4_fsblk_t goal, unsigned long *count, int *errp);
-extern int ext4_claim_free_blocks(struct ext4_sb_info *sbi, s64 nblocks);
+					 ext4_fsblk_t goal,
+					 unsigned int flags,
+					 unsigned long *count,
+					 int *errp);
+extern int ext4_claim_free_blocks(struct ext4_sb_info *sbi,
+				  s64 nblocks, unsigned int flags);
 extern ext4_fsblk_t ext4_count_free_blocks(struct super_block *);
 extern void ext4_check_blocks_bitmap(struct super_block *);
 extern struct ext4_group_desc * ext4_get_group_desc(struct super_block * sb,