[v2,01/12] ext4: add handling for extended mount options

We are running out of mount option bits. This patch adds handling for
using s_mount_opt2 and also adds ability to turn on / off the fast
commit feature. In order to use fast commits, new version e2fsprogs
needs to set the fast feature commit flag. This also makes sure that
we have fast commit compatible e2fsprogs before starting to use the
feature. Mount flag "no_fastcommit", introuced in this patch, can be
passed to disable the feature at mount time.

Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>

---
Changelog:

V2: No changes since V1
---
 fs/ext4/ext4.h       |  4 ++++
 fs/ext4/super.c      | 27 ++++++++++++++++++++++-----
 include/linux/jbd2.h |  5 ++++-
 3 files changed, 30 insertions(+), 6 deletions(-)

On Aug 8, 2019, at 9:45 PM, Harshad Shirwadkar <harshadshirwadkar@gmail.com> wrote:
> 
> We are running out of mount option bits. This patch adds handling for
> using s_mount_opt2 and also adds ability to turn on / off the fast
> commit feature. In order to use fast commits, new version e2fsprogs
> needs to set the fast feature commit flag. This also makes sure that
> we have fast commit compatible e2fsprogs before starting to use the
> feature. Mount flag "no_fastcommit", introuced in this patch, can be
> passed to disable the feature at mount time.
> 
> Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>

Reviewed-by: Andreas Dilger <adilger@dilger.ca>

> 
> ---
> Changelog:
> 
> V2: No changes since V1
> ---
> fs/ext4/ext4.h       |  4 ++++
> fs/ext4/super.c      | 27 ++++++++++++++++++++++-----
> include/linux/jbd2.h |  5 ++++-
> 3 files changed, 30 insertions(+), 6 deletions(-)
> 
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index bf660aa7a9e0..becbda38b7db 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -1146,6 +1146,8 @@ struct ext4_inode_info {
> #define EXT4_MOUNT2_EXPLICIT_JOURNAL_CHECKSUM	0x00000008 /* User explicitly
> 						specified journal checksum */
> 
> +#define EXT4_MOUNT2_JOURNAL_FAST_COMMIT	0x00000010 /* Journal fast commit */
> +
> #define clear_opt(sb, opt)		EXT4_SB(sb)->s_mount_opt &= \
> 						~EXT4_MOUNT_##opt
> #define set_opt(sb, opt)		EXT4_SB(sb)->s_mount_opt |= \
> @@ -1643,6 +1645,7 @@ static inline void ext4_clear_state_flags(struct ext4_inode_info *ei)
> #define EXT4_FEATURE_COMPAT_RESIZE_INODE	0x0010
> #define EXT4_FEATURE_COMPAT_DIR_INDEX		0x0020
> #define EXT4_FEATURE_COMPAT_SPARSE_SUPER2	0x0200
> +#define EXT4_FEATURE_COMPAT_FAST_COMMIT		0x0400
> 
> #define EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER	0x0001
> #define EXT4_FEATURE_RO_COMPAT_LARGE_FILE	0x0002
> @@ -1743,6 +1746,7 @@ EXT4_FEATURE_COMPAT_FUNCS(xattr,		EXT_ATTR)
> EXT4_FEATURE_COMPAT_FUNCS(resize_inode,		RESIZE_INODE)
> EXT4_FEATURE_COMPAT_FUNCS(dir_index,		DIR_INDEX)
> EXT4_FEATURE_COMPAT_FUNCS(sparse_super2,	SPARSE_SUPER2)
> +EXT4_FEATURE_COMPAT_FUNCS(fast_commit,		FAST_COMMIT)
> 
> EXT4_FEATURE_RO_COMPAT_FUNCS(sparse_super,	SPARSE_SUPER)
> EXT4_FEATURE_RO_COMPAT_FUNCS(large_file,	LARGE_FILE)
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 4079605d437a..e376ac040cce 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1455,6 +1455,7 @@ enum {
> 	Opt_dioread_nolock, Opt_dioread_lock,
> 	Opt_discard, Opt_nodiscard, Opt_init_itable, Opt_noinit_itable,
> 	Opt_max_dir_size_kb, Opt_nojournal_checksum, Opt_nombcache,
> +	Opt_no_fastcommit
> };
> 
> static const match_table_t tokens = {
> @@ -1537,6 +1538,7 @@ static const match_table_t tokens = {
> 	{Opt_init_itable, "init_itable=%u"},
> 	{Opt_init_itable, "init_itable"},
> 	{Opt_noinit_itable, "noinit_itable"},
> +	{Opt_no_fastcommit, "no_fastcommit"},
> 	{Opt_max_dir_size_kb, "max_dir_size_kb=%u"},
> 	{Opt_test_dummy_encryption, "test_dummy_encryption"},
> 	{Opt_nombcache, "nombcache"},
> @@ -1659,6 +1661,7 @@ static int clear_qf_name(struct super_block *sb, int qtype)
> #define MOPT_NO_EXT3	0x0200
> #define MOPT_EXT4_ONLY	(MOPT_NO_EXT2 | MOPT_NO_EXT3)
> #define MOPT_STRING	0x0400
> +#define MOPT_2		0x0800
> 
> static const struct mount_opts {
> 	int	token;
> @@ -1751,6 +1754,8 @@ static const struct mount_opts {
> 	{Opt_max_dir_size_kb, 0, MOPT_GTE0},
> 	{Opt_test_dummy_encryption, 0, MOPT_GTE0},
> 	{Opt_nombcache, EXT4_MOUNT_NO_MBCACHE, MOPT_SET},
> +	{Opt_no_fastcommit, EXT4_MOUNT2_JOURNAL_FAST_COMMIT,
> +	 MOPT_CLEAR | MOPT_2 | MOPT_EXT4_ONLY},
> 	{Opt_err, 0, 0}
> };
> 
> @@ -1858,8 +1863,9 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
> 			set_opt2(sb, EXPLICIT_DELALLOC);
> 		} else if (m->mount_opt & EXT4_MOUNT_JOURNAL_CHECKSUM) {
> 			set_opt2(sb, EXPLICIT_JOURNAL_CHECKSUM);
> -		} else
> +		} else if (m->mount_opt) {
> 			return -1;
> +		}
> 	}
> 	if (m->flags & MOPT_CLEAR_ERR)
> 		clear_opt(sb, ERRORS_MASK);
> @@ -2027,10 +2033,17 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
> 			WARN_ON(1);
> 			return -1;
> 		}
> -		if (arg != 0)
> -			sbi->s_mount_opt |= m->mount_opt;
> -		else
> -			sbi->s_mount_opt &= ~m->mount_opt;
> +		if (m->flags & MOPT_2) {
> +			if (arg != 0)
> +				sbi->s_mount_opt2 |= m->mount_opt;
> +			else
> +				sbi->s_mount_opt2 &= ~m->mount_opt;
> +		} else {
> +			if (arg != 0)
> +				sbi->s_mount_opt |= m->mount_opt;
> +			else
> +				sbi->s_mount_opt &= ~m->mount_opt;
> +		}
> 	}
> 	return 1;
> }
> @@ -3733,6 +3746,9 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
> #ifdef CONFIG_EXT4_FS_POSIX_ACL
> 	set_opt(sb, POSIX_ACL);
> #endif
> +	if (ext4_has_feature_fast_commit(sb))
> +		set_opt2(sb, JOURNAL_FAST_COMMIT);
> +
> 	/* don't forget to enable journal_csum when metadata_csum is enabled. */
> 	if (ext4_has_metadata_csum(sb))
> 		set_opt(sb, JOURNAL_CHECKSUM);
> @@ -4334,6 +4350,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
> 		sbi->s_def_mount_opt &= ~EXT4_MOUNT_JOURNAL_CHECKSUM;
> 		clear_opt(sb, JOURNAL_CHECKSUM);
> 		clear_opt(sb, DATA_FLAGS);
> +		clear_opt2(sb, JOURNAL_FAST_COMMIT);
> 		sbi->s_journal = NULL;
> 		needs_recovery = 0;
> 		goto no_journal;
> diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
> index df03825ad1a1..b7eed49b8ecd 100644
> --- a/include/linux/jbd2.h
> +++ b/include/linux/jbd2.h
> @@ -288,6 +288,7 @@ typedef struct journal_superblock_s
> #define JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT	0x00000004
> #define JBD2_FEATURE_INCOMPAT_CSUM_V2		0x00000008
> #define JBD2_FEATURE_INCOMPAT_CSUM_V3		0x00000010
> +#define JBD2_FEATURE_INCOMPAT_FAST_COMMIT	0x00000020
> 
> /* See "journal feature predicate functions" below */
> 
> @@ -298,7 +299,8 @@ typedef struct journal_superblock_s
> 					JBD2_FEATURE_INCOMPAT_64BIT | \
> 					JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT | \
> 					JBD2_FEATURE_INCOMPAT_CSUM_V2 | \
> -					JBD2_FEATURE_INCOMPAT_CSUM_V3)
> +					JBD2_FEATURE_INCOMPAT_CSUM_V3 | \
> +					JBD2_FEATURE_INCOMPAT_FAST_COMMIT)
> 
> #ifdef __KERNEL__
> 
> @@ -1235,6 +1237,7 @@ JBD2_FEATURE_INCOMPAT_FUNCS(64bit,		64BIT)
> JBD2_FEATURE_INCOMPAT_FUNCS(async_commit,	ASYNC_COMMIT)
> JBD2_FEATURE_INCOMPAT_FUNCS(csum2,		CSUM_V2)
> JBD2_FEATURE_INCOMPAT_FUNCS(csum3,		CSUM_V3)
> +JBD2_FEATURE_INCOMPAT_FUNCS(fast_commit,	FAST_COMMIT)
> 
> /*
>  * Journal flag definitions
> --
> 2.23.0.rc1.153.gdeed80330f-goog
> 


Cheers, Andreas

On Thu, Aug 08, 2019 at 08:45:41PM -0700, Harshad Shirwadkar wrote:
> We are running out of mount option bits. This patch adds handling for
> using s_mount_opt2 and also adds ability to turn on / off the fast
> commit feature. In order to use fast commits, new version e2fsprogs
> needs to set the fast feature commit flag. This also makes sure that
> we have fast commit compatible e2fsprogs before starting to use the
> feature. Mount flag "no_fastcommit", introuced in this patch, can be
> passed to disable the feature at mount time.
> 
> Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>

Looks good:

Reviewed-by: Theodore Ts'o <tytso@mit.edu>

					- Ted