ext4: Make sure all the block allocation paths reserve blocks

[karo-tx-linux.git] / fs / ext4 / balloc.c

diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index 344ec1ca8aeb32d1e7f177478ff33685916a5c92..1c0edd85dcca3b9a241899e245e504e86fbda261 100644 (file)
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -1754,6 +1754,32 @@ out:
        return ret;
 }
 
+int ext4_claim_free_blocks(struct ext4_sb_info *sbi,
+                                               ext4_fsblk_t nblocks)
+{
+       s64 free_blocks;
+       ext4_fsblk_t root_blocks = 0;
+       struct percpu_counter *fbc = &sbi->s_freeblocks_counter;
+
+       free_blocks = percpu_counter_read(fbc);
+
+       if (!capable(CAP_SYS_RESOURCE) &&
+               sbi->s_resuid != current->fsuid &&
+               (sbi->s_resgid == 0 || !in_group_p(sbi->s_resgid)))
+               root_blocks = ext4_r_blocks_count(sbi->s_es);
+
+       if (free_blocks - (nblocks + root_blocks) < EXT4_FREEBLOCKS_WATERMARK)
+               free_blocks = percpu_counter_sum(&sbi->s_freeblocks_counter);
+
+       if (free_blocks < (root_blocks + nblocks))
+               /* we don't have free space */
+               return -ENOSPC;
+
+       /* reduce fs free blocks counter */
+       percpu_counter_sub(fbc, nblocks);
+       return 0;
+}
+
 /**
  * ext4_has_free_blocks()
  * @sbi:       in-core super block structure.
@@ -1775,18 +1801,17 @@ ext4_fsblk_t ext4_has_free_blocks(struct ext4_sb_info *sbi,
                sbi->s_resuid != current->fsuid &&
                (sbi->s_resgid == 0 || !in_group_p(sbi->s_resgid)))
                root_blocks = ext4_r_blocks_count(sbi->s_es);
-#ifdef CONFIG_SMP
-       if (free_blocks - root_blocks < FBC_BATCH)
-               free_blocks =
-                       percpu_counter_sum(&sbi->s_freeblocks_counter);
-#endif
+
+       if (free_blocks - (nblocks + root_blocks) < EXT4_FREEBLOCKS_WATERMARK)
+               free_blocks = percpu_counter_sum_positive(&sbi->s_freeblocks_counter);
+
        if (free_blocks <= root_blocks)
                /* we don't have free space */
                return 0;
        if (free_blocks - root_blocks < nblocks)
                return free_blocks - root_blocks;
        return nblocks;
- }
+}
 
 
 /**
@@ -1865,14 +1890,11 @@ ext4_fsblk_t ext4_old_new_blocks(handle_t *handle, struct inode *inode,
                /*
                 * With delalloc we already reserved the blocks
                 */
-               *count = ext4_has_free_blocks(sbi, *count);
-       }
-       if (*count == 0) {
-               *errp = -ENOSPC;
-               return 0;       /*return with ENOSPC error */
+               if (ext4_claim_free_blocks(sbi, *count)) {
+                       *errp = -ENOSPC;
+                       return 0;       /*return with ENOSPC error */
+               }
        }
-       num = *count;
-
        /*
         * Check quota for allocation of this block.
         */
@@ -2067,9 +2089,13 @@ allocated:
        le16_add_cpu(&gdp->bg_free_blocks_count, -num);
        gdp->bg_checksum = ext4_group_desc_csum(sbi, group_no, gdp);
        spin_unlock(sb_bgl_lock(sbi, group_no));
-       if (!EXT4_I(inode)->i_delalloc_reserved_flag)
-               percpu_counter_sub(&sbi->s_freeblocks_counter, num);
-
+       if (!EXT4_I(inode)->i_delalloc_reserved_flag && (*count != num)) {
+               /*
+                * we allocated less blocks than we
+                * claimed. Add the difference back.
+                */
+               percpu_counter_add(&sbi->s_freeblocks_counter, *count - num);
+       }
        if (sbi->s_log_groups_per_flex) {
                ext4_group_t flex_group = ext4_flex_group(sbi, group_no);
                spin_lock(sb_bgl_lock(sbi, flex_group));