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, 26 insertions, 18 deletions

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 9f61e62f435f..4de42090c41f 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -3086,9 +3086,12 @@ ext4_mb_mark_diskspace_used(struct ext4_allocation_context *ac,
         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
+        else {
                 percpu_counter_sub(&sbi->s_dirtyblocks_counter,
                                                 ac->ac_b_ex.fe_len);
+                /* convert reserved quota blocks to real quota blocks */
+                vfs_dq_claim_block(ac->ac_inode, ac->ac_b_ex.fe_len);
+        }
 
         if (sbi->s_log_groups_per_flex) {
                 ext4_group_t flex_group = ext4_flex_group(sbi,
@@ -4544,7 +4547,7 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle,
         struct ext4_sb_info *sbi;
         struct super_block *sb;
         ext4_fsblk_t block = 0;
-        unsigned int inquota;
+        unsigned int inquota = 0;
         unsigned int reserv_blks = 0;
 
         sb = ar->inode->i_sb;
@@ -4562,9 +4565,17 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle,
                    (unsigned long long) ar->pleft,
                    (unsigned long long) ar->pright);
 
-        if (!EXT4_I(ar->inode)->i_delalloc_reserved_flag) {
-                /*
-                 * With delalloc we already reserved the blocks
+        /*
+         * For delayed allocation, we could skip the ENOSPC and
+         * EDQUOT check, as blocks and quotas have been already
+         * reserved when data being copied into pagecache.
+         */
+        if (EXT4_I(ar->inode)->i_delalloc_reserved_flag)
+                ar->flags |= EXT4_MB_DELALLOC_RESERVED;
+        else {
+                /* Without delayed allocation we need to verify
+                 * there is enough free blocks to do block allocation
+                 * and verify allocation doesn't exceed the quota limits.
                  */
                 while (ar->len && ext4_claim_free_blocks(sbi, ar->len)) {
                         /* let others to free the space */
@@ -4576,19 +4587,16 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle,
                         return 0;
                 }
                 reserv_blks = ar->len;
+                while (ar->len && DQUOT_ALLOC_BLOCK(ar->inode, ar->len)) {
+                        ar->flags |= EXT4_MB_HINT_NOPREALLOC;
+                        ar->len--;
+                }
+                inquota = ar->len;
+                if (ar->len == 0) {
+                        *errp = -EDQUOT;
+                        goto out3;
+                }
         }
-        while (ar->len && DQUOT_ALLOC_BLOCK(ar->inode, ar->len)) {
-                ar->flags |= EXT4_MB_HINT_NOPREALLOC;
-                ar->len--;
-        }
-        if (ar->len == 0) {
-                *errp = -EDQUOT;
-                goto out3;
-        }
-        inquota = ar->len;
-
-        if (EXT4_I(ar->inode)->i_delalloc_reserved_flag)
-                ar->flags |= EXT4_MB_DELALLOC_RESERVED;
 
         ac = kmem_cache_alloc(ext4_ac_cachep, GFP_NOFS);
         if (!ac) {
@@ -4654,7 +4662,7 @@ repeat:
 out2:
         kmem_cache_free(ext4_ac_cachep, ac);
 out1:
-        if (ar->len < inquota)
+        if (inquota && ar->len < inquota)
                 DQUOT_FREE_BLOCK(ar->inode, inquota - ar->len);
 out3:
         if (!ar->len) {