ext4: Add percpu dirty block accounting.

This patch adds dirty block accounting using percpu_counters.  Delayed
allocation block reservation is now done by updating dirty block
counter.  In a later patch we switch to non delalloc mode if the
filesystem free blocks is greater than 150% of total filesystem dirty
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, 14 insertions, 17 deletions

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index e4f30de11a9d..585c25950184 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2880,7 +2880,7 @@ void exit_ext4_mballoc(void)
  */
 static noinline_for_stack int
 ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
-                                handle_t *handle)
+                                handle_t *handle, unsigned long reserv_blks)
 {
         struct buffer_head *bitmap_bh = NULL;
         struct ext4_super_block *es;
@@ -2969,21 +2969,16 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
         le16_add_cpu(&gdp->bg_free_blocks_count, -ac->ac_b_ex.fe_len);
         gdp->bg_checksum = ext4_group_desc_csum(sbi, ac->ac_b_ex.fe_group, gdp);
         spin_unlock(sb_bgl_lock(sbi, ac->ac_b_ex.fe_group));
-
+        percpu_counter_sub(&sbi->s_freeblocks_counter, ac->ac_b_ex.fe_len);
         /*
-         * free blocks account has already be reduced/reserved
-         * at write_begin() time for delayed allocation
-         * do not double accounting
+         * Now reduce the dirty block count also. Should not go negative
          */
-        if (!(ac->ac_flags & EXT4_MB_DELALLOC_RESERVED) &&
-                        ac->ac_o_ex.fe_len != ac->ac_b_ex.fe_len) {
-                /*
-                 * we allocated less blocks than we calimed
-                 * Add the difference back
-                 */
-                percpu_counter_add(&sbi->s_freeblocks_counter,
-                                ac->ac_o_ex.fe_len - ac->ac_b_ex.fe_len);
-        }
+        if (!(ac->ac_flags & EXT4_MB_DELALLOC_RESERVED))
+                /* release all the reserved blocks if non delalloc */
+                percpu_counter_sub(&sbi->s_dirtyblocks_counter, reserv_blks);
+        else
+                percpu_counter_sub(&sbi->s_dirtyblocks_counter,
+                                                ac->ac_b_ex.fe_len);
 
         if (sbi->s_log_groups_per_flex) {
                 ext4_group_t flex_group = ext4_flex_group(sbi,
@@ -4376,12 +4371,13 @@ static int ext4_mb_discard_preallocations(struct super_block *sb, int needed)
 ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle,
                                  struct ext4_allocation_request *ar, int *errp)
 {
+        int freed;
         struct ext4_allocation_context *ac = NULL;
         struct ext4_sb_info *sbi;
         struct super_block *sb;
         ext4_fsblk_t block = 0;
-        int freed;
-        int inquota;
+        unsigned long inquota;
+        unsigned long reserv_blks = 0;
 
         sb = ar->inode->i_sb;
         sbi = EXT4_SB(sb);
@@ -4404,6 +4400,7 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle,
                         *errp = -ENOSPC;
                         return 0;
                 }
+                reserv_blks = ar->len;
         }
         while (ar->len && DQUOT_ALLOC_BLOCK(ar->inode, ar->len)) {
                 ar->flags |= EXT4_MB_HINT_NOPREALLOC;
@@ -4450,7 +4447,7 @@ repeat:
         }
 
         if (likely(ac->ac_status == AC_STATUS_FOUND)) {
-                *errp = ext4_mb_mark_diskspace_used(ac, handle);
+                *errp = ext4_mb_mark_diskspace_used(ac, handle, reserv_blks);
                 if (*errp ==  -EAGAIN) {
                         ac->ac_b_ex.fe_group = 0;
                         ac->ac_b_ex.fe_start = 0;