linux-kernel - [PATCH 1/4] f2fs: avoid very large discard command

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Date:   Wed, 22 Feb 2017 20:28:47 -0800
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Cc:     Jaegeuk Kim <jaegeuk@...nel.org>
Subject: [PATCH 1/4] f2fs: avoid very large discard command

This patch adds MAX_DISCARD_BLOCKS() to avoid issuing too much large single
discard command.

Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
---
 fs/f2fs/f2fs.h    | 3 ++-
 fs/f2fs/segment.c | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index d076b94530bc..5f3fe97df055 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -133,7 +133,8 @@ enum {
 		(SM_I(sbi)->trim_sections * (sbi)->segs_per_sec)
 #define BATCHED_TRIM_BLOCKS(sbi)	\
 		(BATCHED_TRIM_SEGMENTS(sbi) << (sbi)->log_blocks_per_seg)
-
+#define MAX_DISCARD_BLOCKS(sbi)						\
+		((1 << (sbi)->log_blocks_per_seg) * (sbi)->segs_per_sec)
 #define DISCARD_ISSUE_RATE	8
 #define DEF_CP_INTERVAL			60	/* 60 secs */
 #define DEF_IDLE_INTERVAL		5	/* 5 secs */
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index fe434cd872b4..567019940e9b 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -886,7 +886,8 @@ static void __add_discard_entry(struct f2fs_sb_info *sbi,
 	if (!list_empty(head)) {
 		last = list_last_entry(head, struct discard_entry, list);
 		if (START_BLOCK(sbi, cpc->trim_start) + start ==
-						last->blkaddr + last->len) {
+				last->blkaddr + last->len &&
+				last->len < MAX_DISCARD_BLOCKS(sbi)) {
 			last->len += end - start;
 			goto done;
 		}
-- 
2.11.0