ext4: quota reservation for delayed allocation

Uses quota reservation/claim/release to handle quota properly for delayed
allocation in the three steps: 1) quotas are reserved when data being copied
to cache when block allocation is defered 2) when new blocks are allocated.
reserved quotas are converted to the real allocated quota, 2) over-booked
quotas for metadata blocks are released back.

Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Acked-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Jan Kara <jack@suse.cz>

1 files changed, 33 insertions, 3 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index c7fed5b18745..8290cfbd9fa7 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -975,6 +975,17 @@ out:
         return err;
 }
 
+qsize_t ext4_get_reserved_space(struct inode *inode)
+{
+        unsigned long long total;
+
+        spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
+        total = EXT4_I(inode)->i_reserved_data_blocks +
+                EXT4_I(inode)->i_reserved_meta_blocks;
+        spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
+
+        return total;
+}
 /*
  * Calculate the number of metadata blocks need to reserve
  * to allocate @blocks for non extent file based file
@@ -1036,8 +1047,14 @@ static void ext4_da_update_reserve_space(struct inode *inode, int used)
         /* update per-inode reservations */
         BUG_ON(used  > EXT4_I(inode)->i_reserved_data_blocks);
         EXT4_I(inode)->i_reserved_data_blocks -= used;
-
         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
+
+        /*
+         * free those over-booking quota for metadata blocks
+         */
+
+        if (mdb_free)
+                vfs_dq_release_reservation_block(inode, mdb_free);
 }
 
 /*
@@ -1553,8 +1570,8 @@ static int ext4_journalled_write_end(struct file *file,
 static int ext4_da_reserve_space(struct inode *inode, int nrblocks)
 {
         int retries = 0;
-       struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
-       unsigned long md_needed, mdblocks, total = 0;
+        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+        unsigned long md_needed, mdblocks, total = 0;
 
         /*
          * recalculate the amount of metadata blocks to reserve
@@ -1570,12 +1587,23 @@ repeat:
         md_needed = mdblocks - EXT4_I(inode)->i_reserved_meta_blocks;
         total = md_needed + nrblocks;
 
+        /*
+         * Make quota reservation here to prevent quota overflow
+         * later. Real quota accounting is done at pages writeout
+         * time.
+         */
+        if (vfs_dq_reserve_block(inode, total)) {
+                spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
+                return -EDQUOT;
+        }
+
         if (ext4_claim_free_blocks(sbi, total)) {
                 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
                 if (ext4_should_retry_alloc(inode->i_sb, &retries)) {
                         yield();
                         goto repeat;
                 }
+                vfs_dq_release_reservation_block(inode, total);
                 return -ENOSPC;
         }
         EXT4_I(inode)->i_reserved_data_blocks += nrblocks;
@@ -1629,6 +1657,8 @@ static void ext4_da_release_space(struct inode *inode, int to_free)
         BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
         EXT4_I(inode)->i_reserved_meta_blocks = mdb;
         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
+
+        vfs_dq_release_reservation_block(inode, release);
 }
 
 static void ext4_da_page_release_reservation(struct page *page,