Re: [PATCH v13 21/51] ext4: Add richacl feature flag

[Andreas Dilger]

> On Nov 3, 2015, at 8:16 AM, Andreas Gruenbacher <agruenba@xxxxxxxxxx> wrote:
> 
> From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
> 
> This feature flag selects richacl instead of posix acl support on the
> file system. In addition, the "acl" mount option is needed for enabling
> either of the two kinds of acls.

This patch confuses me.  I thought the whole point of INCOMPAT_RICHACL
was that the filesystem should never, ever be mounted without ACL support
because the ACLs will get confused without it.  In that case, it doesn't
make sense to have a mount option that _has_ to be specified to mount the
filesystem, and returns an error when trying to disable it.

It makes more sense to just enable "acl" by default if INCOMPAT_RICHACL
is set in the superblock and not need the mount option at all.

Having a mount option made more sense when enabling this support was optional
for the filesystem, and it could be mounted without it enabled, but you
wanted INCOMPAT_RICHACL to prevent that so it needs to be fixed.

Cheers, Andreas

> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
> ---
> fs/ext4/ext4.h  |  6 ++++--
> fs/ext4/super.c | 49 ++++++++++++++++++++++++++++++++++++++++---------
> 2 files changed, 44 insertions(+), 11 deletions(-)
> 
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index fd1f28b..b97a3b1 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -991,7 +991,7 @@ struct ext4_inode_info {
> #define EXT4_MOUNT_UPDATE_JOURNAL	0x01000	/* Update the journal format */
> #define EXT4_MOUNT_NO_UID32		0x02000  /* Disable 32-bit UIDs */
> #define EXT4_MOUNT_XATTR_USER		0x04000	/* Extended user attributes */
> -#define EXT4_MOUNT_POSIX_ACL		0x08000	/* POSIX Access Control Lists */
> +#define EXT4_MOUNT_ACL			0x08000	/* Access Control Lists */
> #define EXT4_MOUNT_NO_AUTO_DA_ALLOC	0x10000	/* No auto delalloc mapping */
> #define EXT4_MOUNT_BARRIER		0x20000 /* Use block barriers */
> #define EXT4_MOUNT_QUOTA		0x80000 /* Some quota option set */
> @@ -1582,6 +1582,7 @@ static inline int ext4_encrypted_inode(struct inode *inode)
> #define EXT4_FEATURE_INCOMPAT_LARGEDIR		0x4000 /* >2GB or 3-lvl htree */
> #define EXT4_FEATURE_INCOMPAT_INLINE_DATA	0x8000 /* data in inode */
> #define EXT4_FEATURE_INCOMPAT_ENCRYPT		0x10000
> +#define EXT4_FEATURE_INCOMPAT_RICHACL		0x20000
> 
> #define EXT2_FEATURE_COMPAT_SUPP	EXT4_FEATURE_COMPAT_EXT_ATTR
> #define EXT2_FEATURE_INCOMPAT_SUPP	(EXT4_FEATURE_INCOMPAT_FILETYPE| \
> @@ -1607,7 +1608,8 @@ static inline int ext4_encrypted_inode(struct inode *inode)
> 					 EXT4_FEATURE_INCOMPAT_FLEX_BG| \
> 					 EXT4_FEATURE_INCOMPAT_MMP | \
> 					 EXT4_FEATURE_INCOMPAT_INLINE_DATA | \
> -					 EXT4_FEATURE_INCOMPAT_ENCRYPT)
> +					 EXT4_FEATURE_INCOMPAT_ENCRYPT | \
> +					 EXT4_FEATURE_INCOMPAT_RICHACL)
> #define EXT4_FEATURE_RO_COMPAT_SUPP	(EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER| \
> 					 EXT4_FEATURE_RO_COMPAT_LARGE_FILE| \
> 					 EXT4_FEATURE_RO_COMPAT_GDT_CSUM| \
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index a63c7b0..7457ea8 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -1270,6 +1270,28 @@ static ext4_fsblk_t get_sb_block(void **data)
> 	return sb_block;
> }
> 
> +static int enable_acl(struct super_block *sb)
> +{
> +	sb->s_flags &= ~(MS_POSIXACL | MS_RICHACL);
> +	if (test_opt(sb, ACL)) {
> +		if (EXT4_HAS_INCOMPAT_FEATURE(sb,
> +					      EXT4_FEATURE_INCOMPAT_RICHACL)) {
> +#ifdef CONFIG_EXT4_FS_RICHACL
> +			sb->s_flags |= MS_RICHACL;
> +#else
> +			return -EOPNOTSUPP;
> +#endif
> +		} else {
> +#ifdef CONFIG_EXT4_FS_POSIX_ACL
> +			sb->s_flags |= MS_POSIXACL;
> +#else
> +			return -EOPNOTSUPP;
> +#endif
> +		}
> +	}
> +	return 0;
> +}
> +
> #define DEFAULT_JOURNAL_IOPRIO (IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, 3))
> static char deprecated_msg[] = "Mount option \"%s\" will be removed by %s\n"
> 	"Contact linux-ext4@xxxxxxxxxxxxxxx if you think we should keep it.\n";
> @@ -1416,9 +1438,9 @@ static const struct mount_opts {
> 	 MOPT_NO_EXT2 | MOPT_DATAJ},
> 	{Opt_user_xattr, EXT4_MOUNT_XATTR_USER, MOPT_SET},
> 	{Opt_nouser_xattr, EXT4_MOUNT_XATTR_USER, MOPT_CLEAR},
> -#ifdef CONFIG_EXT4_FS_POSIX_ACL
> -	{Opt_acl, EXT4_MOUNT_POSIX_ACL, MOPT_SET},
> -	{Opt_noacl, EXT4_MOUNT_POSIX_ACL, MOPT_CLEAR},
> +#if defined(CONFIG_EXT4_FS_POSIX_ACL) || defined(CONFIG_EXT4_FS_RICHACL)
> +	{Opt_acl, EXT4_MOUNT_ACL, MOPT_SET},
> +	{Opt_noacl, EXT4_MOUNT_ACL, MOPT_CLEAR},
> #else
> 	{Opt_acl, 0, MOPT_NOSUPPORT},
> 	{Opt_noacl, 0, MOPT_NOSUPPORT},
> @@ -1466,6 +1488,13 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
> #endif
> 	switch (token) {
> 	case Opt_noacl:
> +#ifdef CONFIG_EXT4_FS_RICHACL
> +	if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RICHACL)) {
> +		ext4_msg(sb, KERN_ERR, "Mount option \"%s\" incompatible "
> +			 "with richacl feature", opt);
> +		return -1;
> +	}
> +#endif
> 	case Opt_nouser_xattr:
> 		ext4_msg(sb, KERN_WARNING, deprecated_msg, opt, "3.5");
> 		break;
> @@ -3576,8 +3605,8 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
> 		set_opt(sb, NO_UID32);
> 	/* xattr user namespace & acls are now defaulted on */
> 	set_opt(sb, XATTR_USER);
> -#ifdef CONFIG_EXT4_FS_POSIX_ACL
> -	set_opt(sb, POSIX_ACL);
> +#if defined(CONFIG_EXT4_FS_POSIX_ACL) || defined(CONFIG_EXT4_FS_RICHACL)
> +	set_opt(sb, ACL);
> #endif
> 	/* don't forget to enable journal_csum when metadata_csum is enabled. */
> 	if (ext4_has_metadata_csum(sb))
> @@ -3660,8 +3689,9 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
> 		sb->s_iflags |= SB_I_CGROUPWB;
> 	}
> 
> -	sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
> -		(test_opt(sb, POSIX_ACL) ? MS_POSIXACL : 0);
> +	err = enable_acl(sb);
> +	if (err)
> +		goto failed_mount;
> 
> 	if (le32_to_cpu(es->s_rev_level) == EXT4_GOOD_OLD_REV &&
> 	    (EXT4_HAS_COMPAT_FEATURE(sb, ~0U) ||
> @@ -4981,8 +5011,9 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
> 	if (sbi->s_mount_flags & EXT4_MF_FS_ABORTED)
> 		ext4_abort(sb, "Abort forced by user");
> 
> -	sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
> -		(test_opt(sb, POSIX_ACL) ? MS_POSIXACL : 0);
> +	err = enable_acl(sb);
> +	if (err)
> +		goto restore_opts;
> 
> 	es = sbi->s_es;
> 
> --
> 2.5.0
> 


Cheers, Andreas

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