ext4: delayed allocation ENOSPC handling

This patch does block reservation for delayed
allocation, to avoid ENOSPC later at page flush time.

Blocks(data and metadata) are reserved at da_write_begin()
time, the freeblocks counter is updated by then, and the number of
reserved blocks is store in per inode counter.
        
At the writepage time, the unused reserved meta blocks are returned
back. At unlink/truncate time, reserved blocks are properly released.

Updated fix from  Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
to fix the oldallocator block reservation accounting with delalloc, added
lock to guard the counters and also fix the reservation for meta blocks.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 5 insertions, 1 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index ee9576dc0ba1..0962f4e26579 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -74,6 +74,9 @@
 #define EXT4_MB_HINT_GOAL_ONLY          256
 /* goal is meaningful */
 #define EXT4_MB_HINT_TRY_GOAL           512
+/* blocks already pre-reserved by delayed allocation */
+#define EXT4_MB_DELALLOC_RESERVED      1024
+
 
 struct ext4_allocation_request {
         /* target inode for block we're allocating */
@@ -1041,6 +1044,7 @@ extern void ext4_mb_update_group_info(struct ext4_group_info *grp,
 
 
 /* inode.c */
+void ext4_da_release_space(struct inode *inode, int used, int to_free);
 int ext4_forget(handle_t *handle, int is_metadata, struct inode *inode,
                 struct buffer_head *bh, ext4_fsblk_t blocknr);
 struct buffer_head *ext4_getblk(handle_t *, struct inode *,
@@ -1234,7 +1238,7 @@ extern long ext4_fallocate(struct inode *inode, int mode, loff_t offset,
 extern int ext4_get_blocks_wrap(handle_t *handle, struct inode *inode,
                         sector_t block, unsigned long max_blocks,
                         struct buffer_head *bh, int create,
-                        int extend_disksize);
+                        int extend_disksize, int flag);
 #endif  /* __KERNEL__ */
 
 #endif  /* _EXT4_H */