5 files changed, 73 insertions, 44 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 56f9271ee8cc..af7b62699ea9 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -699,6 +699,8 @@ struct ext4_inode_info {
         unsigned int i_reserved_meta_blocks;
         unsigned int i_allocated_meta_blocks;
         unsigned short i_delalloc_reserved_flag;
+        sector_t i_da_metadata_calc_last_lblock;
+        int i_da_metadata_calc_len;
 
         /* on-disk additional length */
         __u16 i_extra_isize;
diff --git a/fs/ext4/ext4_extents.h b/fs/ext4/ext4_extents.h
index 2ca686454e87..bdb6ce7e2eb4 100644
--- a/fs/ext4/ext4_extents.h
+++ b/fs/ext4/ext4_extents.h
@@ -225,7 +225,8 @@ static inline void ext4_ext_mark_initialized(struct ext4_extent *ext)
         ext->ee_len = cpu_to_le16(ext4_ext_get_actual_len(ext));
 }
 
-extern int ext4_ext_calc_metadata_amount(struct inode *inode, int blocks);
+extern int ext4_ext_calc_metadata_amount(struct inode *inode,
+                                         sector_t lblocks);
 extern ext4_fsblk_t ext_pblock(struct ext4_extent *ex);
 extern ext4_fsblk_t idx_pblock(struct ext4_extent_idx *);
 extern void ext4_ext_store_pblock(struct ext4_extent *, ext4_fsblk_t);
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 91ae46098ea4..7d7b74e94687 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -296,29 +296,44 @@ static inline int ext4_ext_space_root_idx(struct inode *inode, int check)
  * to allocate @blocks
  * Worse case is one block per extent
  */
-int ext4_ext_calc_metadata_amount(struct inode *inode, int blocks)
+int ext4_ext_calc_metadata_amount(struct inode *inode, sector_t lblock)
 {
-        int lcap, icap, rcap, leafs, idxs, num;
-        int newextents = blocks;
-
-        rcap = ext4_ext_space_root_idx(inode, 0);
-        lcap = ext4_ext_space_block(inode, 0);
-        icap = ext4_ext_space_block_idx(inode, 0);
+        struct ext4_inode_info *ei = EXT4_I(inode);
+        int idxs, num = 0;
 
-        /* number of new leaf blocks needed */
-        num = leafs = (newextents + lcap - 1) / lcap;
+        idxs = ((inode->i_sb->s_blocksize - sizeof(struct ext4_extent_header))
+                / sizeof(struct ext4_extent_idx));
 
         /*
-         * Worse case, we need separate index block(s)
-         * to link all new leaf blocks
+         * If the new delayed allocation block is contiguous with the
+         * previous da block, it can share index blocks with the
+         * previous block, so we only need to allocate a new index
+         * block every idxs leaf blocks.  At ldxs**2 blocks, we need
+         * an additional index block, and at ldxs**3 blocks, yet
+         * another index blocks.
          */
-        idxs = (leafs + icap - 1) / icap;
-        do {
-                num += idxs;
-                idxs = (idxs + icap - 1) / icap;
-        } while (idxs > rcap);
+        if (ei->i_da_metadata_calc_len &&
+            ei->i_da_metadata_calc_last_lblock+1 == lblock) {
+                if ((ei->i_da_metadata_calc_len % idxs) == 0)
+                        num++;
+                if ((ei->i_da_metadata_calc_len % (idxs*idxs)) == 0)
+                        num++;
+                if ((ei->i_da_metadata_calc_len % (idxs*idxs*idxs)) == 0) {
+                        num++;
+                        ei->i_da_metadata_calc_len = 0;
+                } else
+                        ei->i_da_metadata_calc_len++;
+                ei->i_da_metadata_calc_last_lblock++;
+                return num;
+        }
 
-        return num;
+        /*
+         * In the worst case we need a new set of index blocks at
+         * every level of the inode's extent tree.
+         */
+        ei->i_da_metadata_calc_len = 1;
+        ei->i_da_metadata_calc_last_lblock = lblock;
+        return ext_depth(inode) + 1;
 }
 
 static int
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index bdaa92a29e0e..c818972c8302 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1009,38 +1009,44 @@ qsize_t *ext4_get_reserved_space(struct inode *inode)
         return &EXT4_I(inode)->i_reserved_quota;
 }
 #endif
+
 /*
  * Calculate the number of metadata blocks need to reserve
- * to allocate @blocks for non extent file based file
+ * to allocate a new block at @lblocks for non extent file based file
  */
-static int ext4_indirect_calc_metadata_amount(struct inode *inode, int blocks)
+static int ext4_indirect_calc_metadata_amount(struct inode *inode,
+                                              sector_t lblock)
 {
-        int icap = EXT4_ADDR_PER_BLOCK(inode->i_sb);
-        int ind_blks, dind_blks, tind_blks;
-
-        /* number of new indirect blocks needed */
-        ind_blks = (blocks + icap - 1) / icap;
+        struct ext4_inode_info *ei = EXT4_I(inode);
+        int dind_mask = EXT4_ADDR_PER_BLOCK(inode->i_sb) - 1;
+        int blk_bits;
 
-        dind_blks = (ind_blks + icap - 1) / icap;
+        if (lblock < EXT4_NDIR_BLOCKS)
+                return 0;
 
-        tind_blks = 1;
+        lblock -= EXT4_NDIR_BLOCKS;
 
-        return ind_blks + dind_blks + tind_blks;
+        if (ei->i_da_metadata_calc_len &&
+            (lblock & dind_mask) == ei->i_da_metadata_calc_last_lblock) {
+                ei->i_da_metadata_calc_len++;
+                return 0;
+        }
+        ei->i_da_metadata_calc_last_lblock = lblock & dind_mask;
+        ei->i_da_metadata_calc_len = 1;
+        blk_bits = roundup_pow_of_two(lblock + 1);
+        return (blk_bits / EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb)) + 1;
 }
 
 /*
  * Calculate the number of metadata blocks need to reserve
- * to allocate given number of blocks
+ * to allocate a block located at @lblock
  */
-static int ext4_calc_metadata_amount(struct inode *inode, int blocks)
+static int ext4_calc_metadata_amount(struct inode *inode, sector_t lblock)
 {
-        if (!blocks)
-                return 0;
-
         if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)
-                return ext4_ext_calc_metadata_amount(inode, blocks);
+                return ext4_ext_calc_metadata_amount(inode, lblock);
 
-        return ext4_indirect_calc_metadata_amount(inode, blocks);
+        return ext4_indirect_calc_metadata_amount(inode, lblock);
 }
 
 /*
@@ -1078,6 +1084,7 @@ static void ext4_da_update_reserve_space(struct inode *inode, int used)
                  */
                 mdb_free = ei->i_reserved_meta_blocks;
                 ei->i_reserved_meta_blocks = 0;
+                ei->i_da_metadata_calc_len = 0;
                 percpu_counter_sub(&sbi->s_dirtyblocks_counter, mdb_free);
         }
         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
@@ -1802,12 +1809,15 @@ static int ext4_journalled_write_end(struct file *file,
         return ret ? ret : copied;
 }
 
-static int ext4_da_reserve_space(struct inode *inode, int nrblocks)
+/*
+ * Reserve a single block located at lblock
+ */
+static int ext4_da_reserve_space(struct inode *inode, sector_t lblock)
 {
         int retries = 0;
         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
         struct ext4_inode_info *ei = EXT4_I(inode);
-        unsigned long md_needed, md_reserved, total = 0;
+        unsigned long md_needed, md_reserved;
 
         /*
          * recalculate the amount of metadata blocks to reserve
@@ -1817,8 +1827,7 @@ static int ext4_da_reserve_space(struct inode *inode, int nrblocks)
 repeat:
         spin_lock(&ei->i_block_reservation_lock);
         md_reserved = ei->i_reserved_meta_blocks;
-        md_needed = ext4_calc_metadata_amount(inode, nrblocks);
-        total = md_needed + nrblocks;
+        md_needed = ext4_calc_metadata_amount(inode, lblock);
         spin_unlock(&ei->i_block_reservation_lock);
 
         /*
@@ -1826,7 +1835,7 @@ repeat:
          * later. Real quota accounting is done at pages writeout
          * time.
          */
-        if (vfs_dq_reserve_block(inode, total)) {
+        if (vfs_dq_reserve_block(inode, md_needed + 1)) {
                 /* 
                  * We tend to badly over-estimate the amount of
                  * metadata blocks which are needed, so if we have
@@ -1838,8 +1847,8 @@ repeat:
                 return -EDQUOT;
         }
 
-        if (ext4_claim_free_blocks(sbi, total)) {
-                vfs_dq_release_reservation_block(inode, total);
+        if (ext4_claim_free_blocks(sbi, md_needed + 1)) {
+                vfs_dq_release_reservation_block(inode, md_needed + 1);
                 if (ext4_should_retry_alloc(inode->i_sb, &retries)) {
                 retry:
                         if (md_reserved)
@@ -1850,7 +1859,7 @@ repeat:
                 return -ENOSPC;
         }
         spin_lock(&ei->i_block_reservation_lock);
-        ei->i_reserved_data_blocks += nrblocks;
+        ei->i_reserved_data_blocks++;
         ei->i_reserved_meta_blocks += md_needed;
         spin_unlock(&ei->i_block_reservation_lock);
 
@@ -1891,6 +1900,7 @@ static void ext4_da_release_space(struct inode *inode, int to_free)
                  */
                 to_free += ei->i_reserved_meta_blocks;
                 ei->i_reserved_meta_blocks = 0;
+                ei->i_da_metadata_calc_len = 0;
         }
 
         /* update fs dirty blocks counter */
@@ -2504,7 +2514,7 @@ static int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
                  * XXX: __block_prepare_write() unmaps passed block,
                  * is it OK?
                  */
-                ret = ext4_da_reserve_space(inode, 1);
+                ret = ext4_da_reserve_space(inode, iblock);
                 if (ret)
                         /* not enough space to reserve */
                         return ret;
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 7cccb35c0f4d..735c20d5fd56 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -702,6 +702,7 @@ static struct inode *ext4_alloc_inode(struct super_block *sb)
         ei->i_reserved_data_blocks = 0;
         ei->i_reserved_meta_blocks = 0;
         ei->i_allocated_meta_blocks = 0;
+        ei->i_da_metadata_calc_len = 0;
         ei->i_delalloc_reserved_flag = 0;
         spin_lock_init(&(ei->i_block_reservation_lock));
 #ifdef CONFIG_QUOTA