Commit 27b38686 authored by Ojaswin Mujoo's avatar Ojaswin Mujoo Committed by Theodore Ts'o
Browse files

ext4: make mb_optimize_scan option work with set/unset mount cmd 



After moving to the new mount API, mb_optimize_scan mount option
handling was not working as expected due to the parsed value always
being overwritten by default. Refactor and fix this to the expected
behavior described below:

*  mb_optimize_scan=1 - On
*  mb_optimize_scan=0 - Off
*  mb_optimize_scan not passed - On if no. of BGs > threshold else off
*  Remounts retain previous value unless we explicitly pass the option
   with a new value

Fixes: cebe85d5 ("ext4: switch to the new mount api")
Cc: stable@kernel.org
Reported-by: default avatarRitesh Harjani <riteshh@linux.ibm.com>
Signed-off-by: default avatarOjaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: default avatarRitesh Harjani <riteshh@linux.ibm.com>
Link: https://lore.kernel.org/r/c98970fe99f26718586d02e942f293300fb48ef3.1646732698.git.ojaswin@linux.ibm.com


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent cc509574

fs/ext4/super.c

+14 −10
Original line number Diff line number Diff line
@@ -2021,12 +2021,12 @@ static int ext4_set_test_dummy_encryption(struct super_block *sb, char *arg) 
#define EXT4_SPEC_s_commit_interval		(1 << 16)

#define EXT4_SPEC_s_fc_debug_max_replay		(1 << 17)

#define EXT4_SPEC_s_sb_block			(1 << 18)

#define EXT4_SPEC_mb_optimize_scan		(1 << 19)



struct ext4_fs_context {

	char		*s_qf_names[EXT4_MAXQUOTAS];

	char		*test_dummy_enc_arg;

	int		s_jquota_fmt;	/* Format of quota to use */

	int		mb_optimize_scan;

#ifdef CONFIG_EXT4_DEBUG

	int s_fc_debug_max_replay;

#endif
@@ -2464,12 +2464,17 @@ static int ext4_parse_param(struct fs_context *fc, struct fs_parameter *param) 
			ctx_clear_mount_opt(ctx, m->mount_opt);

		return 0;

	case Opt_mb_optimize_scan:

		if (result.int_32 != 0 && result.int_32 != 1) {

		if (result.int_32 == 1) {

			ctx_set_mount_opt2(ctx, EXT4_MOUNT2_MB_OPTIMIZE_SCAN);

			ctx->spec |= EXT4_SPEC_mb_optimize_scan;

		} else if (result.int_32 == 0) {

			ctx_clear_mount_opt2(ctx, EXT4_MOUNT2_MB_OPTIMIZE_SCAN);

			ctx->spec |= EXT4_SPEC_mb_optimize_scan;

		} else {

			ext4_msg(NULL, KERN_WARNING,

				 "mb_optimize_scan should be set to 0 or 1.");

			return -EINVAL;

		}

		ctx->mb_optimize_scan = result.int_32;

		return 0;

	}
@@ -4398,7 +4403,6 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb) 


	/* Set defaults for the variables that will be set during parsing */

	ctx->journal_ioprio = DEFAULT_JOURNAL_IOPRIO;

	ctx->mb_optimize_scan = DEFAULT_MB_OPTIMIZE_SCAN;



	sbi->s_inode_readahead_blks = EXT4_DEF_INODE_READAHEAD_BLKS;

	sbi->s_sectors_written_start =
@@ -5349,12 +5353,12 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb) 
	 * turned off by passing "mb_optimize_scan=0". This can also be

	 * turned on forcefully by passing "mb_optimize_scan=1".

	 */

	if (ctx->mb_optimize_scan == 1)

	if (!(ctx->spec & EXT4_SPEC_mb_optimize_scan)) {

		if (sbi->s_groups_count >= MB_DEFAULT_LINEAR_SCAN_THRESHOLD)

			set_opt2(sb, MB_OPTIMIZE_SCAN);

	else if (ctx->mb_optimize_scan == 0)

		else

			clear_opt2(sb, MB_OPTIMIZE_SCAN);

	else if (sbi->s_groups_count >= MB_DEFAULT_LINEAR_SCAN_THRESHOLD)

		set_opt2(sb, MB_OPTIMIZE_SCAN);

	}



	err = ext4_mb_init(sb);

	if (err) {