f2fs: Add option to limit required GC for checkpoint=disable

This extends the checkpoint option to allow checkpoint=disable:%u[%]
This allows you to specify what how much of the disk you are willing
to lose access to while mounting with checkpoint=disable. If the amount
lost would be higher, the mount will return -EAGAIN. This can be given
as a percent of total space, or in blocks.

Currently, we need to run garbage collection until the amount of holes
is smaller than the OVP space. With the new option, f2fs can mark
space as unusable up front instead of requiring garbage collection until
the number of holes is small enough.

Signed-off-by: Daniel Rosenberg <drosen@google.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 38 insertions, 21 deletions

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 4b547024571f..15d7e30bfc72 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -136,7 +136,10 @@ enum {
 	Opt_alloc,
 	Opt_fsync,
 	Opt_test_dummy_encryption,
-	Opt_checkpoint,
+	Opt_checkpoint_disable,
+	Opt_checkpoint_disable_cap,
+	Opt_checkpoint_disable_cap_perc,
+	Opt_checkpoint_enable,
 	Opt_err,
 };
 
@@ -195,7 +198,10 @@ static match_table_t f2fs_tokens = {
 	{Opt_alloc, "alloc_mode=%s"},
 	{Opt_fsync, "fsync_mode=%s"},
 	{Opt_test_dummy_encryption, "test_dummy_encryption"},
-	{Opt_checkpoint, "checkpoint=%s"},
+	{Opt_checkpoint_disable, "checkpoint=disable"},
+	{Opt_checkpoint_disable_cap, "checkpoint=disable:%u"},
+	{Opt_checkpoint_disable_cap_perc, "checkpoint=disable:%u%%"},
+	{Opt_checkpoint_enable, "checkpoint=enable"},
 	{Opt_err, NULL},
 };
 
@@ -772,22 +778,30 @@ static int parse_options(struct super_block *sb, char *options)
 					"Test dummy encryption mount option ignored");
 #endif
 			break;
-		case Opt_checkpoint:
-			name = match_strdup(&args[0]);
-			if (!name)
-				return -ENOMEM;
-
-			if (strlen(name) == 6 &&
-					!strncmp(name, "enable", 6)) {
-				clear_opt(sbi, DISABLE_CHECKPOINT);
-			} else if (strlen(name) == 7 &&
-					!strncmp(name, "disable", 7)) {
-				set_opt(sbi, DISABLE_CHECKPOINT);
-			} else {
-				kvfree(name);
+		case Opt_checkpoint_disable_cap_perc:
+			if (args->from && match_int(args, &arg))
 				return -EINVAL;
-			}
-			kvfree(name);
+			if (arg < 0 || arg > 100)
+				return -EINVAL;
+			if (arg == 100)
+				F2FS_OPTION(sbi).unusable_cap =
+					sbi->user_block_count;
+			else
+				F2FS_OPTION(sbi).unusable_cap =
+					(sbi->user_block_count / 100) *	arg;
+			set_opt(sbi, DISABLE_CHECKPOINT);
+			break;
+		case Opt_checkpoint_disable_cap:
+			if (args->from && match_int(args, &arg))
+				return -EINVAL;
+			F2FS_OPTION(sbi).unusable_cap = arg;
+			set_opt(sbi, DISABLE_CHECKPOINT);
+			break;
+		case Opt_checkpoint_disable:
+			set_opt(sbi, DISABLE_CHECKPOINT);
+			break;
+		case Opt_checkpoint_enable:
+			clear_opt(sbi, DISABLE_CHECKPOINT);
 			break;
 		default:
 			f2fs_msg(sb, KERN_ERR,
@@ -1412,8 +1426,8 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
 		seq_printf(seq, ",alloc_mode=%s", "reuse");
 
 	if (test_opt(sbi, DISABLE_CHECKPOINT))
-		seq_puts(seq, ",checkpoint=disable");
-
+		seq_printf(seq, ",checkpoint=disable:%u",
+				F2FS_OPTION(sbi).unusable_cap);
 	if (F2FS_OPTION(sbi).fsync_mode == FSYNC_MODE_POSIX)
 		seq_printf(seq, ",fsync_mode=%s", "posix");
 	else if (F2FS_OPTION(sbi).fsync_mode == FSYNC_MODE_STRICT)
@@ -1442,6 +1456,7 @@ static void default_options(struct f2fs_sb_info *sbi)
 	set_opt(sbi, EXTENT_CACHE);
 	set_opt(sbi, NOHEAP);
 	clear_opt(sbi, DISABLE_CHECKPOINT);
+	F2FS_OPTION(sbi).unusable_cap = 0;
 	sbi->sb->s_flags |= SB_LAZYTIME;
 	set_opt(sbi, FLUSH_MERGE);
 	set_opt(sbi, DISCARD);
@@ -1470,6 +1485,7 @@ static int f2fs_disable_checkpoint(struct f2fs_sb_info *sbi)
 	struct cp_control cpc;
 	int err = 0;
 	int ret;
+	block_t unusable;
 
 	if (s_flags & SB_RDONLY) {
 		f2fs_msg(sbi->sb, KERN_ERR,
@@ -1497,7 +1513,8 @@ static int f2fs_disable_checkpoint(struct f2fs_sb_info *sbi)
 		goto restore_flag;
 	}
 
-	if (f2fs_disable_cp_again(sbi)) {
+	unusable = f2fs_get_unusable_blocks(sbi);
+	if (f2fs_disable_cp_again(sbi, unusable)) {
 		err = -EAGAIN;
 		goto restore_flag;
 	}
@@ -1510,7 +1527,7 @@ static int f2fs_disable_checkpoint(struct f2fs_sb_info *sbi)
 		goto out_unlock;
 
 	spin_lock(&sbi->stat_lock);
-	sbi->unusable_block_count = 0;
+	sbi->unusable_block_count = unusable;
 	spin_unlock(&sbi->stat_lock);
 
 out_unlock: