f2fs: compress: use more readable atomic_t type for {cic,dic}.ref

refcount_t type variable should never be less than one, so it's a
little bit hard to understand when we use it to indicate pending
compressed page count, let's change to use atomic_t for better
readability.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/compress.c

@@ -677,7 +677,7 @@ void f2fs_decompress_pages(struct bio *bio, struct page *page, bool verity)
 	if (bio->bi_status || PageError(page))
 		dic->failed = true;
 
-	if (refcount_dec_not_one(&dic->ref))
+	if (atomic_dec_return(&dic->pending_pages))
 		return;
 
 	trace_f2fs_decompress_pages_start(dic->inode, dic->cluster_idx,
@@ -746,7 +746,7 @@ void f2fs_decompress_pages(struct bio *bio, struct page *page, bool verity)
 		cops->destroy_decompress_ctx(dic);
 out_free_dic:
 	if (verity)
-		refcount_set(&dic->ref, dic->nr_cpages);
+		atomic_set(&dic->pending_pages, dic->nr_cpages);
 	if (!verity)
 		f2fs_decompress_end_io(dic->rpages, dic->cluster_size,
 								ret, false);
@@ -1161,7 +1161,7 @@ static int f2fs_write_compressed_pages(struct compress_ctx *cc,
 
 	cic->magic = F2FS_COMPRESSED_PAGE_MAGIC;
 	cic->inode = inode;
-	refcount_set(&cic->ref, cc->nr_cpages);
+	atomic_set(&cic->pending_pages, cc->nr_cpages);
 	cic->rpages = f2fs_kzalloc(sbi, sizeof(struct page *) <<
 			cc->log_cluster_size, GFP_NOFS);
 	if (!cic->rpages)
@@ -1296,7 +1296,7 @@ void f2fs_compress_write_end_io(struct bio *bio, struct page *page)
 
 	dec_page_count(sbi, F2FS_WB_DATA);
 
-	if (refcount_dec_not_one(&cic->ref))
+	if (atomic_dec_return(&cic->pending_pages))
 		return;
 
 	for (i = 0; i < cic->nr_rpages; i++) {
@@ -1438,7 +1438,7 @@ struct decompress_io_ctx *f2fs_alloc_dic(struct compress_ctx *cc)
 
 	dic->magic = F2FS_COMPRESSED_PAGE_MAGIC;
 	dic->inode = cc->inode;
-	refcount_set(&dic->ref, cc->nr_cpages);
+	atomic_set(&dic->pending_pages, cc->nr_cpages);
 	dic->cluster_idx = cc->cluster_idx;
 	dic->cluster_size = cc->cluster_size;
 	dic->log_cluster_size = cc->log_cluster_size;

fs/f2fs/data.c

@@ -202,7 +202,7 @@ static void f2fs_verify_bio(struct bio *bio)
 		dic = (struct decompress_io_ctx *)page_private(page);
 
 		if (dic) {
-			if (refcount_dec_not_one(&dic->ref))
+			if (atomic_dec_return(&dic->pending_pages))
 				continue;
 			f2fs_verify_pages(dic->rpages,
 						dic->cluster_size);
@@ -2272,8 +2272,8 @@ int f2fs_read_multi_pages(struct compress_ctx *cc, struct bio **bio_ret,
 			if (IS_ERR(bio)) {
 				ret = PTR_ERR(bio);
 				dic->failed = true;
-				if (refcount_sub_and_test(dic->nr_cpages - i,
-							&dic->ref)) {
+				if (!atomic_sub_return(dic->nr_cpages - i,
+							&dic->pending_pages)) {
 					f2fs_decompress_end_io(dic->rpages,
 							cc->cluster_size, true,
 							false);

fs/f2fs/f2fs.h

@@ -1376,7 +1376,7 @@ struct compress_io_ctx {
 	struct inode *inode;		/* inode the context belong to */
 	struct page **rpages;		/* pages store raw data in cluster */
 	unsigned int nr_rpages;		/* total page number in rpages */
-	refcount_t ref;			/* referrence count of raw page */
+	atomic_t pending_pages;		/* in-flight compressed page count */
 };
 
 /* decompress io context for read IO path */
@@ -1395,7 +1395,7 @@ struct decompress_io_ctx {
 	struct compress_data *cbuf;	/* virtual mapped address on cpages */
 	size_t rlen;			/* valid data length in rbuf */
 	size_t clen;			/* valid data length in cbuf */
-	refcount_t ref;			/* referrence count of compressed page */
+	atomic_t pending_pages;		/* in-flight compressed page count */
 	bool failed;			/* indicate IO error during decompression */
 	void *private;			/* payload buffer for specified decompression algorithm */
 	void *private2;			/* extra payload buffer */