ext4: rename ext4_has_free_blocks() to ext4_has_free_clusters()

Rename the function so it is more clear what is going on.  Also rename
the various variables so it's clearer what's happening.

Also fix a missing blocks to cluster conversion when reading the
number of reserved blocks for root.
Signed-off-by: N"Theodore Ts'o" <tytso@mit.edu>

fs/ext4/balloc.c

@@ -403,42 +403,43 @@ ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
 }
 
 /**
- * ext4_has_free_blocks()
+ * ext4_has_free_clusters()
  * @sbi:	in-core super block structure.
- * @nblocks:	number of needed blocks
+ * @nclusters:	number of needed blocks
+ * @flags:	flags from ext4_mb_new_blocks()
  *
- * Check if filesystem has nblocks free & available for allocation.
+ * Check if filesystem has nclusters free & available for allocation.
  * On success return 1, return 0 on failure.
  */
-static int ext4_has_free_blocks(struct ext4_sb_info *sbi,
-				s64 nblocks, unsigned int flags)
+static int ext4_has_free_clusters(struct ext4_sb_info *sbi,
+				  s64 nclusters, unsigned int flags)
 {
-	s64 free_blocks, dirty_blocks, root_blocks;
+	s64 free_clusters, dirty_clusters, root_clusters;
 	struct percpu_counter *fcc = &sbi->s_freeclusters_counter;
-	struct percpu_counter *dbc = &sbi->s_dirtyclusters_counter;
+	struct percpu_counter *dcc = &sbi->s_dirtyclusters_counter;
 
-	free_blocks  = percpu_counter_read_positive(fcc);
-	dirty_blocks = percpu_counter_read_positive(dbc);
-	root_blocks = ext4_r_blocks_count(sbi->s_es);
+	free_clusters  = percpu_counter_read_positive(fcc);
+	dirty_clusters = percpu_counter_read_positive(dcc);
+	root_clusters = EXT4_B2C(sbi, ext4_r_blocks_count(sbi->s_es));
 
-	if (free_blocks - (nblocks + root_blocks + dirty_blocks) <
-						EXT4_FREEBLOCKS_WATERMARK) {
-		free_blocks  = EXT4_C2B(sbi, percpu_counter_sum_positive(fcc));
-		dirty_blocks = percpu_counter_sum_positive(dbc);
+	if (free_clusters - (nclusters + root_clusters + dirty_clusters) <
+					EXT4_FREECLUSTERS_WATERMARK) {
+		free_clusters  = EXT4_C2B(sbi, percpu_counter_sum_positive(fcc));
+		dirty_clusters = percpu_counter_sum_positive(dcc);
 	}
-	/* Check whether we have space after
-	 * accounting for current dirty blocks & root reserved blocks.
+	/* Check whether we have space after accounting for current
+	 * dirty clusters & root reserved clusters.
 	 */
-	if (free_blocks >= ((root_blocks + nblocks) + dirty_blocks))
+	if (free_clusters >= ((root_clusters + nclusters) + dirty_clusters))
 		return 1;
 
-	/* Hm, nope.  Are (enough) root reserved blocks available? */
+	/* Hm, nope.  Are (enough) root reserved clusters available? */
 	if (sbi->s_resuid == current_fsuid() ||
 	    ((sbi->s_resgid != 0) && in_group_p(sbi->s_resgid)) ||
 	    capable(CAP_SYS_RESOURCE) ||
 		(flags & EXT4_MB_USE_ROOT_BLOCKS)) {
 
-		if (free_blocks >= (nblocks + dirty_blocks))
+		if (free_clusters >= (nclusters + dirty_clusters))
 			return 1;
 	}
 
@@ -448,7 +449,7 @@ static int ext4_has_free_blocks(struct ext4_sb_info *sbi,
 int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
 			     s64 nclusters, unsigned int flags)
 {
-	if (ext4_has_free_blocks(sbi, nclusters, flags)) {
+	if (ext4_has_free_clusters(sbi, nclusters, flags)) {
 		percpu_counter_add(&sbi->s_dirtyclusters_counter, nclusters);
 		return 0;
 	} else
@@ -469,7 +470,7 @@ int ext4_claim_free_clusters(struct ext4_sb_info *sbi,
  */
 int ext4_should_retry_alloc(struct super_block *sb, int *retries)
 {
-	if (!ext4_has_free_blocks(EXT4_SB(sb), 1, 0) ||
+	if (!ext4_has_free_clusters(EXT4_SB(sb), 1, 0) ||
 	    (*retries)++ > 3 ||
 	    !EXT4_SB(sb)->s_journal)
 		return 0;

fs/ext4/ext4.h

@@ -2103,13 +2103,13 @@ do {								\
 } while (0)
 
 #ifdef CONFIG_SMP
-/* Each CPU can accumulate percpu_counter_batch blocks in their local
- * counters. So we need to make sure we have free blocks more
+/* Each CPU can accumulate percpu_counter_batch clusters in their local
+ * counters. So we need to make sure we have free clusters more
  * than percpu_counter_batch  * nr_cpu_ids. Also add a window of 4 times.
  */
-#define EXT4_FREEBLOCKS_WATERMARK (4 * (percpu_counter_batch * nr_cpu_ids))
+#define EXT4_FREECLUSTERS_WATERMARK (4 * (percpu_counter_batch * nr_cpu_ids))
 #else
-#define EXT4_FREEBLOCKS_WATERMARK 0
+#define EXT4_FREECLUSTERS_WATERMARK 0
 #endif
 
 static inline void ext4_update_i_disksize(struct inode *inode, loff_t newsize)

fs/ext4/inode.c

@@ -2255,7 +2255,7 @@ static int ext4_nonda_switch(struct super_block *sb)
 		percpu_counter_read_positive(&sbi->s_freeclusters_counter));
 	dirty_blocks = percpu_counter_read_positive(&sbi->s_dirtyclusters_counter);
 	if (2 * free_blocks < 3 * dirty_blocks ||
-		free_blocks < (dirty_blocks + EXT4_FREEBLOCKS_WATERMARK)) {
+		free_blocks < (dirty_blocks + EXT4_FREECLUSTERS_WATERMARK)) {
 		/*
 		 * free block count is less than 150% of dirty blocks
 		 * or free blocks is less than watermark