ext4: Cleanup the block reservation code path

The truncate patch should not use the i_allocated_meta_blocks
value. So add seperate functions to be used in the truncate
and alloc path. We also need to release the meta-data block
that we reserved for the blocks that we are truncating.

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

2 files changed, 67 insertions, 42 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 303e41cf7b14..6c7924d9e358 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1044,7 +1044,6 @@ 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 *,
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 2697eaf0368f..85a862c9c4cc 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -980,6 +980,67 @@ out:
         return err;
 }
 
+/*
+ * Calculate the number of metadata blocks need to reserve
+ * to allocate @blocks for non extent file based file
+ */
+static int ext4_indirect_calc_metadata_amount(struct inode *inode, int blocks)
+{
+        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;
+
+        dind_blks = (ind_blks + icap - 1) / icap;
+
+        tind_blks = 1;
+
+        return ind_blks + dind_blks + tind_blks;
+}
+
+/*
+ * Calculate the number of metadata blocks need to reserve
+ * to allocate given number of blocks
+ */
+static int ext4_calc_metadata_amount(struct inode *inode, int blocks)
+{
+        if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)
+                return ext4_ext_calc_metadata_amount(inode, blocks);
+
+        return ext4_indirect_calc_metadata_amount(inode, blocks);
+}
+
+static void ext4_da_update_reserve_space(struct inode *inode, int used)
+{
+        struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+        int total, mdb, mdb_free;
+
+        spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
+        /* recalculate the number of metablocks still need to be reserved */
+        total = EXT4_I(inode)->i_reserved_data_blocks - used;
+        mdb = ext4_calc_metadata_amount(inode, total);
+
+        /* figure out how many metablocks to release */
+        BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
+        mdb_free = EXT4_I(inode)->i_reserved_meta_blocks - mdb;
+
+        /* Account for allocated meta_blocks */
+        mdb_free -= EXT4_I(inode)->i_allocated_meta_blocks;
+
+        /* update fs free blocks counter for truncate case */
+        percpu_counter_add(&sbi->s_freeblocks_counter, mdb_free);
+
+        /* update per-inode reservations */
+        BUG_ON(used  > EXT4_I(inode)->i_reserved_data_blocks);
+        EXT4_I(inode)->i_reserved_data_blocks -= used;
+
+        BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
+        EXT4_I(inode)->i_reserved_meta_blocks = mdb;
+        EXT4_I(inode)->i_allocated_meta_blocks = 0;
+        spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
+}
+
 /* Maximum number of blocks we map for direct IO at once. */
 #define DIO_MAX_BLOCKS 4096
 /*
@@ -1097,7 +1158,7 @@ int ext4_get_blocks_wrap(handle_t *handle, struct inode *inode, sector_t block,
                  * which were deferred till now
                  */
                 if ((retval > 0) && buffer_delay(bh))
-                        ext4_da_release_space(inode, retval, 0);
+                        ext4_da_update_reserve_space(inode, retval);
         }
 
         up_write((&EXT4_I(inode)->i_data_sem));
@@ -1465,36 +1526,6 @@ static int ext4_journalled_write_end(struct file *file,
 
         return ret ? ret : copied;
 }
-/*
- * Calculate the number of metadata blocks need to reserve
- * to allocate @blocks for non extent file based file
- */
-static int ext4_indirect_calc_metadata_amount(struct inode *inode, int blocks)
-{
-        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;
-
-        dind_blks = (ind_blks + icap - 1) / icap;
-
-        tind_blks = 1;
-
-        return ind_blks + dind_blks + tind_blks;
-}
-
-/*
- * Calculate the number of metadata blocks need to reserve
- * to allocate given number of blocks
- */
-static int ext4_calc_metadata_amount(struct inode *inode, int blocks)
-{
-        if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)
-                return ext4_ext_calc_metadata_amount(inode, blocks);
-
-        return ext4_indirect_calc_metadata_amount(inode, blocks);
-}
 
 static int ext4_da_reserve_space(struct inode *inode, int nrblocks)
 {
@@ -1518,7 +1549,6 @@ static int ext4_da_reserve_space(struct inode *inode, int nrblocks)
                 spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
                 return -ENOSPC;
         }
-
         /* reduce fs free blocks counter */
         percpu_counter_sub(&sbi->s_freeblocks_counter, total);
 
@@ -1529,35 +1559,31 @@ static int ext4_da_reserve_space(struct inode *inode, int nrblocks)
         return 0;       /* success */
 }
 
-void ext4_da_release_space(struct inode *inode, int used, int to_free)
+static void ext4_da_release_space(struct inode *inode, int to_free)
 {
         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
         int total, mdb, mdb_free, release;
 
         spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
         /* recalculate the number of metablocks still need to be reserved */
-        total = EXT4_I(inode)->i_reserved_data_blocks - used - to_free;
+        total = EXT4_I(inode)->i_reserved_data_blocks - to_free;
         mdb = ext4_calc_metadata_amount(inode, total);
 
         /* figure out how many metablocks to release */
         BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
         mdb_free = EXT4_I(inode)->i_reserved_meta_blocks - mdb;
 
-        /* Account for allocated meta_blocks */
-        mdb_free -= EXT4_I(inode)->i_allocated_meta_blocks;
-
         release = to_free + mdb_free;
 
         /* update fs free blocks counter for truncate case */
         percpu_counter_add(&sbi->s_freeblocks_counter, release);
 
         /* update per-inode reservations */
-        BUG_ON(used + to_free > EXT4_I(inode)->i_reserved_data_blocks);
-        EXT4_I(inode)->i_reserved_data_blocks -= (used + to_free);
+        BUG_ON(to_free > EXT4_I(inode)->i_reserved_data_blocks);
+        EXT4_I(inode)->i_reserved_data_blocks -= to_free;
 
         BUG_ON(mdb > EXT4_I(inode)->i_reserved_meta_blocks);
         EXT4_I(inode)->i_reserved_meta_blocks = mdb;
-        EXT4_I(inode)->i_allocated_meta_blocks = 0;
         spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
 }
 
@@ -1579,7 +1605,7 @@ static void ext4_da_page_release_reservation(struct page *page,
                 }
                 curr_off = next_off;
         } while ((bh = bh->b_this_page) != head);
-        ext4_da_release_space(page->mapping->host, 0, to_release);
+        ext4_da_release_space(page->mapping->host, to_release);
 }
 
 /*