f2fs: introduce DEFAULT_IO_TIMEOUT

As Geert Uytterhoeven reported:

for parameter HZ/50 in congestion_wait(BLK_RW_ASYNC, HZ/50);

On some platforms, HZ can be less than 50, then unexpected 0 timeout
jiffies will be set in congestion_wait().

This patch introduces a macro DEFAULT_IO_TIMEOUT to wrap a determinate
value with msecs_to_jiffies(20) to instead HZ/50 to avoid such issue.

Quoted from Geert Uytterhoeven:

"A timeout of HZ means 1 second.
HZ/50 means 20 ms, but has the risk of being zero, if HZ < 50.

If you want to use a timeout of 20 ms, you best use msecs_to_jiffies(20),
as that takes care of the special cases, and never returns 0."
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/checkpoint.c

@@ -1260,7 +1260,7 @@ void f2fs_wait_on_all_pages(struct f2fs_sb_info *sbi, int type)
 		if (unlikely(f2fs_cp_error(sbi)))
 			break;
 
-		io_schedule_timeout(HZ/50);
+		io_schedule_timeout(DEFAULT_IO_TIMEOUT);
 	}
 	finish_wait(&sbi->cp_wait, &wait);
 }

fs/f2fs/compress.c

@@ -988,7 +988,8 @@ static int f2fs_write_raw_pages(struct compress_ctx *cc,
 			} else if (ret == -EAGAIN) {
 				ret = 0;
 				cond_resched();
-				congestion_wait(BLK_RW_ASYNC, HZ/50);
+				congestion_wait(BLK_RW_ASYNC,
+						DEFAULT_IO_TIMEOUT);
 				lock_page(cc->rpages[i]);
 				clear_page_dirty_for_io(cc->rpages[i]);
 				goto retry_write;

fs/f2fs/data.c

@@ -2317,7 +2317,7 @@ int f2fs_encrypt_one_page(struct f2fs_io_info *fio)
 		/* flush pending IOs and wait for a while in the ENOMEM case */
 		if (PTR_ERR(fio->encrypted_page) == -ENOMEM) {
 			f2fs_flush_merged_writes(fio->sbi);
-			congestion_wait(BLK_RW_ASYNC, HZ/50);
+			congestion_wait(BLK_RW_ASYNC, DEFAULT_IO_TIMEOUT);
 			gfp_flags |= __GFP_NOFAIL;
 			goto retry_encrypt;
 		}
@@ -2908,7 +2908,7 @@ static int f2fs_write_cache_pages(struct address_space *mapping,
 					if (wbc->sync_mode == WB_SYNC_ALL) {
 						cond_resched();
 						congestion_wait(BLK_RW_ASYNC,
-								HZ/50);
+							DEFAULT_IO_TIMEOUT);
 						goto retry_write;
 					}
 					goto next;

fs/f2fs/f2fs.h

@@ -558,6 +558,9 @@ enum {
 
 #define DEFAULT_RETRY_IO_COUNT	8	/* maximum retry read IO count */
 
+/* congestion wait timeout value, default: 20ms */
+#define	DEFAULT_IO_TIMEOUT	(msecs_to_jiffies(20))
+
 /* maximum retry quota flush count */
 #define DEFAULT_RETRY_QUOTA_FLUSH_COUNT		8
 

fs/f2fs/gc.c

@@ -977,7 +977,8 @@ static int move_data_page(struct inode *inode, block_t bidx, int gc_type,
 		if (err) {
 			clear_cold_data(page);
 			if (err == -ENOMEM) {
-				congestion_wait(BLK_RW_ASYNC, HZ/50);
+				congestion_wait(BLK_RW_ASYNC,
+						DEFAULT_IO_TIMEOUT);
 				goto retry;
 			}
 			if (is_dirty)

fs/f2fs/inode.c

@@ -535,7 +535,7 @@ struct inode *f2fs_iget_retry(struct super_block *sb, unsigned long ino)
 	inode = f2fs_iget(sb, ino);
 	if (IS_ERR(inode)) {
 		if (PTR_ERR(inode) == -ENOMEM) {
-			congestion_wait(BLK_RW_ASYNC, HZ/50);
+			congestion_wait(BLK_RW_ASYNC, DEFAULT_IO_TIMEOUT);
 			goto retry;
 		}
 	}

fs/f2fs/node.c

@@ -2599,7 +2599,7 @@ int f2fs_recover_inode_page(struct f2fs_sb_info *sbi, struct page *page)
 retry:
 	ipage = f2fs_grab_cache_page(NODE_MAPPING(sbi), ino, false);
 	if (!ipage) {
-		congestion_wait(BLK_RW_ASYNC, HZ/50);
+		congestion_wait(BLK_RW_ASYNC, DEFAULT_IO_TIMEOUT);
 		goto retry;
 	}
 

fs/f2fs/recovery.c

@@ -534,7 +534,7 @@ static int do_recover_data(struct f2fs_sb_info *sbi, struct inode *inode,
 	err = f2fs_get_dnode_of_data(&dn, start, ALLOC_NODE);
 	if (err) {
 		if (err == -ENOMEM) {
-			congestion_wait(BLK_RW_ASYNC, HZ/50);
+			congestion_wait(BLK_RW_ASYNC, DEFAULT_IO_TIMEOUT);
 			goto retry_dn;
 		}
 		goto out;
@@ -617,7 +617,8 @@ static int do_recover_data(struct f2fs_sb_info *sbi, struct inode *inode,
 			err = check_index_in_prev_nodes(sbi, dest, &dn);
 			if (err) {
 				if (err == -ENOMEM) {
-					congestion_wait(BLK_RW_ASYNC, HZ/50);
+					congestion_wait(BLK_RW_ASYNC,
+							DEFAULT_IO_TIMEOUT);
 					goto retry_prev;
 				}
 				goto err;

fs/f2fs/segment.c

@@ -245,7 +245,8 @@ static int __revoke_inmem_pages(struct inode *inode,
 								LOOKUP_NODE);
 			if (err) {
 				if (err == -ENOMEM) {
-					congestion_wait(BLK_RW_ASYNC, HZ/50);
+					congestion_wait(BLK_RW_ASYNC,
+							DEFAULT_IO_TIMEOUT);
 					cond_resched();
 					goto retry;
 				}
@@ -312,7 +313,7 @@ void f2fs_drop_inmem_pages_all(struct f2fs_sb_info *sbi, bool gc_failure)
 skip:
 		iput(inode);
 	}
-	congestion_wait(BLK_RW_ASYNC, HZ/50);
+	congestion_wait(BLK_RW_ASYNC, DEFAULT_IO_TIMEOUT);
 	cond_resched();
 	if (gc_failure) {
 		if (++looped >= count)
@@ -415,7 +416,8 @@ static int __f2fs_commit_inmem_pages(struct inode *inode)
 			err = f2fs_do_write_data_page(&fio);
 			if (err) {
 				if (err == -ENOMEM) {
-					congestion_wait(BLK_RW_ASYNC, HZ/50);
+					congestion_wait(BLK_RW_ASYNC,
+							DEFAULT_IO_TIMEOUT);
 					cond_resched();
 					goto retry;
 				}
@@ -2801,7 +2803,7 @@ static unsigned int __issue_discard_cmd_range(struct f2fs_sb_info *sbi,
 			blk_finish_plug(&plug);
 			mutex_unlock(&dcc->cmd_lock);
 			trimmed += __wait_all_discard_cmd(sbi, NULL);
-			congestion_wait(BLK_RW_ASYNC, HZ/50);
+			congestion_wait(BLK_RW_ASYNC, DEFAULT_IO_TIMEOUT);
 			goto next;
 		}
 skip:

fs/f2fs/super.c

@@ -1885,7 +1885,8 @@ static ssize_t f2fs_quota_read(struct super_block *sb, int type, char *data,
 		page = read_cache_page_gfp(mapping, blkidx, GFP_NOFS);
 		if (IS_ERR(page)) {
 			if (PTR_ERR(page) == -ENOMEM) {
-				congestion_wait(BLK_RW_ASYNC, HZ/50);
+				congestion_wait(BLK_RW_ASYNC,
+						DEFAULT_IO_TIMEOUT);
 				goto repeat;
 			}
 			set_sbi_flag(F2FS_SB(sb), SBI_QUOTA_NEED_REPAIR);
@@ -1939,7 +1940,8 @@ static ssize_t f2fs_quota_write(struct super_block *sb, int type,
 							&page, NULL);
 		if (unlikely(err)) {
 			if (err == -ENOMEM) {
-				congestion_wait(BLK_RW_ASYNC, HZ/50);
+				congestion_wait(BLK_RW_ASYNC,
+						DEFAULT_IO_TIMEOUT);
 				goto retry;
 			}
 			set_sbi_flag(F2FS_SB(sb), SBI_QUOTA_NEED_REPAIR);