linux-ext4 - Re: [PATCH 2/2] ext4: do not allow journal

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Date:	Fri, 9 Oct 2015 14:53:39 -0600
From:	Andreas Dilger <adilger@...ger.ca>
To:	Dmitry Monakhov <dmonakhov@...nvz.org>
Cc:	linux-ext4@...r.kernel.org, tytso@....edu
Subject: Re: [PATCH 2/2] ext4: do not allow journal_opts for fs w/o journal

On Oct 9, 2015, at 3:09 AM, Dmitry Monakhov <dmonakhov@...nvz.org> wrote:
> 
> It is appeared that we can pass journal related mount options and such options
> be shown in /proc/mounts
> 
> Example:
> #mkfs.ext4 -F /dev/vdb
> #tune2fs -O ^has_journal /dev/vdb
> #mount /dev/vdb /mnt/  -ocommit=20,journal_async_commit
> #cat /proc/mounts  | grep /mnt
> /dev/vdb /mnt ext4 rw,relatime,journal_checksum,journal_async_commit,commit=20,data=ordered 0 0
> 
> But options:"journal_checksum,journal_async_commit,commit=20,data=ordered" has
> nothing with reality because there is no jornall at all.

(typo) s/jornall/journal/

but looks reasonable otherwise.

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

> This patch disallow following options for journalless configurations:
> - journal_checksum
> - journal_async_commit
> - commit=%ld
> - data={writeback,ordered,journal}
> 
> Signed-off-by: Dmitry Monakhov <dmonakhov@...nvz.org>
> ---
> fs/ext4/ext4.h  |    3 +++
> fs/ext4/super.c |   31 +++++++++++++++++++++++++++++--
> 2 files changed, 32 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 3f248c9..871cdc6 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -1019,6 +1019,9 @@ struct ext4_inode_info {
> #define EXT4_MOUNT2_HURD_COMPAT		0x00000004 /* Support HURD-castrated
> 						      file systems */
> 
> +#define EXT4_MOUNT2_EXPLICIT_JOURNAL_CHECKSUM	0x00000008 /* User explicitly
> +						specified journal checksum */
> +
> #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 |= \
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index e91f6d4..a29b32b 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1371,10 +1371,10 @@ static const struct mount_opts {
> 	{Opt_nojournal_checksum, EXT4_MOUNT_JOURNAL_CHECKSUM,
> 	 MOPT_EXT4_ONLY | MOPT_CLEAR},
> 	{Opt_journal_checksum, EXT4_MOUNT_JOURNAL_CHECKSUM,
> -	 MOPT_EXT4_ONLY | MOPT_SET},
> +	 MOPT_EXT4_ONLY | MOPT_SET | MOPT_EXPLICIT},
> 	{Opt_journal_async_commit, (EXT4_MOUNT_JOURNAL_ASYNC_COMMIT |
> 				    EXT4_MOUNT_JOURNAL_CHECKSUM),
> -	 MOPT_EXT4_ONLY | MOPT_SET},
> +	 MOPT_EXT4_ONLY | MOPT_SET | MOPT_EXPLICIT},
> 	{Opt_noload, EXT4_MOUNT_NOLOAD, MOPT_NO_EXT2 | MOPT_SET},
> 	{Opt_err_panic, EXT4_MOUNT_ERRORS_PANIC, MOPT_SET | MOPT_CLEAR_ERR},
> 	{Opt_err_ro, EXT4_MOUNT_ERRORS_RO, MOPT_SET | MOPT_CLEAR_ERR},
> @@ -1506,6 +1506,8 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
> 	if (m->flags & MOPT_EXPLICIT) {
> 		if (m->mount_opt & EXT4_MOUNT_DELALLOC) {
> 			set_opt2(sb, EXPLICIT_DELALLOC);
> +		} else if (m->mount_opt & EXT4_MOUNT_JOURNAL_CHECKSUM) {
> +			set_opt2(sb, EXPLICIT_JOURNAL_CHECKSUM);
> 		} else
> 			return -1;
> 	}
> @@ -3675,6 +3677,31 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
> 		       "suppressed and not mounted read-only");
> 		goto failed_mount_wq;
> 	} else {
> +		/* Nojournal mode, all journal mount options are illegal */
> +		if (test_opt2(sb, EXPLICIT_JOURNAL_CHECKSUM)) {
> +			ext4_msg(sb, KERN_ERR, "can't mount with "
> +				 "journal_checksum, fs mounted w/o journal");
> +			goto failed_mount_wq;
> +		}
> +		if (test_opt(sb, JOURNAL_ASYNC_COMMIT)) {
> +			ext4_msg(sb, KERN_ERR, "can't mount with "
> +				 "journal_async_commit, fs mounted w/o journal");
> +			goto failed_mount_wq;
> +		}
> +		if (sbi->s_commit_interval != JBD2_DEFAULT_MAX_COMMIT_AGE*HZ) {
> +			ext4_msg(sb, KERN_ERR, "can't mount with "
> +				 "commit=%lu, fs mounted w/o journal",
> +				 sbi->s_commit_interval / HZ);
> +			goto failed_mount_wq;
> +		}
> +		if (EXT4_MOUNT_DATA_FLAGS &
> +		    (sbi->s_mount_opt ^ sbi->s_def_mount_opt)) {
> +			ext4_msg(sb, KERN_ERR, "can't mount with "
> +				 "data=, fs mounted w/o journal");
> +			goto failed_mount_wq;
> +		}
> +		sbi->s_def_mount_opt &= EXT4_MOUNT_JOURNAL_CHECKSUM;
> +		clear_opt(sb, JOURNAL_CHECKSUM);
> 		clear_opt(sb, DATA_FLAGS);
> 		sbi->s_journal = NULL;
> 		needs_recovery = 0;
> --
> 1.7.1
> 
> --
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Cheers, Andreas






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