patch ext4-make-sure-all-the-block-allocation-paths-reserve-blocks.patch added to 2.6.27-stable tree

--- 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
 		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_
 		/*
 		 * 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));
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1015,6 +1015,8 @@  extern ext4_fsblk_t ext4_new_blocks(hand
 					unsigned long *count, int *errp);
 extern ext4_fsblk_t ext4_old_new_blocks(handle_t *handle, struct inode *inode,
 			ext4_fsblk_t goal, unsigned long *count, int *errp);
+extern int ext4_claim_free_blocks(struct ext4_sb_info *sbi,
+						ext4_fsblk_t nblocks);
 extern ext4_fsblk_t ext4_has_free_blocks(struct ext4_sb_info *sbi,
 						ext4_fsblk_t nblocks);
 extern void ext4_free_blocks (handle_t *handle, struct inode *inode,
@@ -1245,6 +1247,17 @@  do {								\
 		__ext4_std_error((sb), __func__, (errno));	\
 } while (0)
 
+#ifdef CONFIG_SMP
+/* Each CPU can accumulate FBC_BATCH blocks in their local
+ * counters. So we need to make sure we have free blocks more
+ * than FBC_BATCH  * nr_cpu_ids. Also add a window of 4 times.
+ */
+#define EXT4_FREEBLOCKS_WATERMARK (4 * (FBC_BATCH * nr_cpu_ids))
+#else
+#define EXT4_FREEBLOCKS_WATERMARK 0
+#endif
+
+
 /*
  * Inodes and files operations
  */
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1564,13 +1564,10 @@  static int ext4_da_reserve_space(struct
 	md_needed = mdblocks - EXT4_I(inode)->i_reserved_meta_blocks;
 	total = md_needed + nrblocks;
 
-	if (ext4_has_free_blocks(sbi, total) < total) {
+	if (ext4_claim_free_blocks(sbi, total)) {
 		spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
 		return -ENOSPC;
 	}
-	/* reduce fs free blocks counter */
-	percpu_counter_sub(&sbi->s_freeblocks_counter, total);
-
 	EXT4_I(inode)->i_reserved_data_blocks += nrblocks;
 	EXT4_I(inode)->i_reserved_meta_blocks = mdblocks;
 
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -3194,9 +3194,15 @@  ext4_mb_mark_diskspace_used(struct ext4_
 	 * at write_begin() time for delayed allocation
 	 * do not double accounting
 	 */
-	if (!(ac->ac_flags & EXT4_MB_DELALLOC_RESERVED))
-		percpu_counter_sub(&sbi->s_freeblocks_counter,
-					ac->ac_b_ex.fe_len);
+	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 (sbi->s_log_groups_per_flex) {
 		ext4_group_t flex_group = ext4_flex_group(sbi,
@@ -4649,14 +4655,11 @@  ext4_fsblk_t ext4_mb_new_blocks(handle_t
 		/*
 		 * With delalloc we already reserved the blocks
 		 */
-		ar->len = ext4_has_free_blocks(sbi, ar->len);
-	}
-
-	if (ar->len == 0) {
-		*errp = -ENOSPC;
-		return 0;
+		if (ext4_claim_free_blocks(sbi, ar->len)) {
+			*errp = -ENOSPC;
+			return 0;
+		}
 	}
-
 	while (ar->len && DQUOT_ALLOC_BLOCK(ar->inode, ar->len)) {
 		ar->flags |= EXT4_MB_HINT_NOPREALLOC;
 		ar->len--;