f2fs: handle decompress only post processing in softirq

Now decompression is being handled in workqueue and it makes read I/O
latency non-deterministic, because of the non-deterministic scheduling
nature of workqueues. So, I made it handled in softirq context only if
possible, not in low memory devices, since this modification will
maintain decompresion related memory a little longer.

Signed-off-by: Daeho Jeong <daehojeong@google.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 34 insertions, 18 deletions

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index b3dbe77f902b..f48eec8f93e2 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -119,7 +119,7 @@ struct bio_post_read_ctx {
 	block_t fs_blkaddr;
 };
 
-static void f2fs_finish_read_bio(struct bio *bio)
+static void f2fs_finish_read_bio(struct bio *bio, bool in_task)
 {
 	struct bio_vec *bv;
 	struct bvec_iter_all iter_all;
@@ -133,8 +133,9 @@ static void f2fs_finish_read_bio(struct bio *bio)
 
 		if (f2fs_is_compressed_page(page)) {
 			if (bio->bi_status)
-				f2fs_end_read_compressed_page(page, true, 0);
-			f2fs_put_page_dic(page);
+				f2fs_end_read_compressed_page(page, true, 0,
+							in_task);
+			f2fs_put_page_dic(page, in_task);
 			continue;
 		}
 
@@ -191,7 +192,7 @@ static void f2fs_verify_bio(struct work_struct *work)
 		fsverity_verify_bio(bio);
 	}
 
-	f2fs_finish_read_bio(bio);
+	f2fs_finish_read_bio(bio, true);
 }
 
 /*
@@ -203,7 +204,7 @@ static void f2fs_verify_bio(struct work_struct *work)
  * can involve reading verity metadata pages from the file, and these verity
  * metadata pages may be encrypted and/or compressed.
  */
-static void f2fs_verify_and_finish_bio(struct bio *bio)
+static void f2fs_verify_and_finish_bio(struct bio *bio, bool in_task)
 {
 	struct bio_post_read_ctx *ctx = bio->bi_private;
 
@@ -211,7 +212,7 @@ static void f2fs_verify_and_finish_bio(struct bio *bio)
 		INIT_WORK(&ctx->work, f2fs_verify_bio);
 		fsverity_enqueue_verify_work(&ctx->work);
 	} else {
-		f2fs_finish_read_bio(bio);
+		f2fs_finish_read_bio(bio, in_task);
 	}
 }
 
@@ -224,7 +225,8 @@ static void f2fs_verify_and_finish_bio(struct bio *bio)
  * that the bio includes at least one compressed page.  The actual decompression
  * is done on a per-cluster basis, not a per-bio basis.
  */
-static void f2fs_handle_step_decompress(struct bio_post_read_ctx *ctx)
+static void f2fs_handle_step_decompress(struct bio_post_read_ctx *ctx,
+		bool in_task)
 {
 	struct bio_vec *bv;
 	struct bvec_iter_all iter_all;
@@ -237,7 +239,7 @@ static void f2fs_handle_step_decompress(struct bio_post_read_ctx *ctx)
 		/* PG_error was set if decryption failed. */
 		if (f2fs_is_compressed_page(page))
 			f2fs_end_read_compressed_page(page, PageError(page),
-						blkaddr);
+						blkaddr, in_task);
 		else
 			all_compressed = false;
 
@@ -262,15 +264,16 @@ static void f2fs_post_read_work(struct work_struct *work)
 		fscrypt_decrypt_bio(ctx->bio);
 
 	if (ctx->enabled_steps & STEP_DECOMPRESS)
-		f2fs_handle_step_decompress(ctx);
+		f2fs_handle_step_decompress(ctx, true);
 
-	f2fs_verify_and_finish_bio(ctx->bio);
+	f2fs_verify_and_finish_bio(ctx->bio, true);
 }
 
 static void f2fs_read_end_io(struct bio *bio)
 {
 	struct f2fs_sb_info *sbi = F2FS_P_SB(bio_first_page_all(bio));
 	struct bio_post_read_ctx *ctx;
+	bool intask = in_task();
 
 	iostat_update_and_unbind_ctx(bio, 0);
 	ctx = bio->bi_private;
@@ -281,16 +284,29 @@ static void f2fs_read_end_io(struct bio *bio)
 	}
 
 	if (bio->bi_status) {
-		f2fs_finish_read_bio(bio);
+		f2fs_finish_read_bio(bio, intask);
 		return;
 	}
 
-	if (ctx && (ctx->enabled_steps & (STEP_DECRYPT | STEP_DECOMPRESS))) {
-		INIT_WORK(&ctx->work, f2fs_post_read_work);
-		queue_work(ctx->sbi->post_read_wq, &ctx->work);
-	} else {
-		f2fs_verify_and_finish_bio(bio);
+	if (ctx) {
+		unsigned int enabled_steps = ctx->enabled_steps &
+					(STEP_DECRYPT | STEP_DECOMPRESS);
+
+		/*
+		 * If we have only decompression step between decompression and
+		 * decrypt, we don't need post processing for this.
+		 */
+		if (enabled_steps == STEP_DECOMPRESS &&
+				!f2fs_low_mem_mode(sbi)) {
+			f2fs_handle_step_decompress(ctx, intask);
+		} else if (enabled_steps) {
+			INIT_WORK(&ctx->work, f2fs_post_read_work);
+			queue_work(ctx->sbi->post_read_wq, &ctx->work);
+			return;
+		}
 	}
+
+	f2fs_verify_and_finish_bio(bio, intask);
 }
 
 static void f2fs_write_end_io(struct bio *bio)
@@ -2220,7 +2236,7 @@ skip_reading_dnode:
 
 		if (f2fs_load_compressed_page(sbi, page, blkaddr)) {
 			if (atomic_dec_and_test(&dic->remaining_pages))
-				f2fs_decompress_cluster(dic);
+				f2fs_decompress_cluster(dic, true);
 			continue;
 		}
 
@@ -2238,7 +2254,7 @@ submit_and_realloc:
 					page->index, for_write);
 			if (IS_ERR(bio)) {
 				ret = PTR_ERR(bio);
-				f2fs_decompress_end_io(dic, ret);
+				f2fs_decompress_end_io(dic, ret, true);
 				f2fs_put_dnode(&dn);
 				*bio_ret = NULL;
 				return ret;