Patchwork ext4: make quota as first class supported feature

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Submitter Aditya Kali
Date July 20, 2011, 6:40 p.m.
Message ID <1311187218-30798-1-git-send-email-adityakali@google.com>
Download mbox | patch
Permalink /patch/105779/
State Accepted
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Comments

Aditya Kali - July 20, 2011, 6:40 p.m.
This patch is an attempt towards supporting quotas as first class
feature in ext4. It is based on the proposal at:
https://ext4.wiki.kernel.org/index.php/Design_For_1st_Class_Quota_in_Ext4
This patch introduces a new feature - EXT4_FEATURE_RO_COMPAT_QUOTA which, when
turned on, enables quota accounting at mount time iteself. Also, the
quota inodes are stored in two additional superblock fields.
Some changes introduced by this patch that should be pointed out are:
1) Two new ext4-superblock fields - s_usr_quota_inum and s_grp_quota_inum
   for storing the quota inodes in use.
2) Quotas are turned on at mount time irrespective of the quota mount options.
   Thus the mount options 'quota', 'usrquota' and 'grpquota' are completely
   ignored.
3) Default quota inodes are: inode#3 for tracking userquota and inode#4 for
   tracking group quota. The superblock fields can be set to use other inodes
   as well.
4) mke2fs or tune2fs will initialize these inodes when quota feature is
   being set. The default reserved inodes will not be visible to user as
   regular files.
5) Once quotas are turned on, they cannot be turned off while the FS is
   mounted. This is because we do not want to let the quota get inconsistent.
6) Since the quota inodes are hidden, some of the utilities from quota-tools
   will no longer work correctly. Instead, e2fsprogs will include support for
   fixing the quota files.
7) Support is only for QFMT_VFS_V1 quota file format.

Signed-off-by: Aditya Kali <adityakali@google.com>
---
 fs/ext4/ext4.h  |   10 ++++++-
 fs/ext4/super.c |   67 ++++++++++++++++++++++++++++++++++++++----------------
 2 files changed, 55 insertions(+), 22 deletions(-)
Aditya Kali - July 21, 2011, 5:24 p.m.
On Thu, Jul 21, 2011 at 12:02 AM, Andreas Dilger <adilger@dilger.ca> wrote:
> Why support V1 quota, when it has known limits on some of the usage, instead
> of using V2 quotas that are added to ext3/4 already?  The Kconfig comment
> for V1 begins:
>     This quota format was (is) used by kernels earlier than 2.4.22.
> It would make much more sense to start with V2 for a new feature like this.
>
QFMT_VFS_V1 is actually the format ID of V2 quota format itself. This
is whats in fs/quota/quota_v2.c:

313 static struct quota_format_type v2r1_quota_format = {
314         .qf_fmt_id      = QFMT_VFS_V1,
315         .qf_ops         = &v2_format_ops,
316         .qf_owner       = THIS_MODULE
317 };

So this patch does support the V2 format.


> static const struct quotactl_ops ext4_qctl_operations = {
> -    .quota_on    = ext4_quota_on,
> +    .quota_on_meta    = ext4_quota_on,
>    .quota_off    = ext4_quota_off,
>    .quota_sync    = dquot_quota_sync,
>    .get_info    = dquot_get_dqinfo,

> @@ -4658,24 +4679,22 @@ static int ext4_quota_on_mount(struct super_block
> *sb, int type)
> /*
>  * Standard function to be called on quota_on
>  */
> -static int ext4_quota_on(struct super_block *sb, int type, int format_id,
> -             struct path *path)
> +static int ext4_quota_on(struct super_block *sb, int type, int format_id)
> {
>    int err;
> +    struct inode *qf_inode;
>
> -    if (!test_opt(sb, QUOTA))
> +    if (!EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_QUOTA) ||
> +        !EXT4_SB(sb)->s_qf_inums[type])
>        return -EINVAL;
>
I also wanted to get input on this change to ext4_quota_on. With this
change, its not possible to use quotas at all without the 'quota'
feature flag set, which might break the current userspace. Do we want
to keep supporting current approach (where quotas can be turned on
with user specified files) as well? This change kinda forces users to
update userspace tools (e2fsprogs & quota-tools) as well.

Thanks,
-Aditya
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Theodore Ts'o - Aug. 1, 2011, 2 p.m.
On Wed, Jul 20, 2011 at 11:40:18AM -0700, Aditya Kali wrote:
> This patch is an attempt towards supporting quotas as first class
> feature in ext4. It is based on the proposal at:
> https://ext4.wiki.kernel.org/index.php/Design_For_1st_Class_Quota_in_Ext4
> ...
>
> Signed-off-by: Aditya Kali <adityakali@google.com>

Thanks, added to the ext4 tree.

						- Ted

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Patch

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 1921392..256fdd8 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1062,7 +1062,9 @@  struct ext4_super_block {
 	__u8	s_last_error_func[32];	/* function where the error happened */
 #define EXT4_S_ERR_END offsetof(struct ext4_super_block, s_mount_opts)
 	__u8	s_mount_opts[64];
-	__le32	s_reserved[112];        /* Padding to the end of the block */
+	__le32	s_usr_quota_inum;	/* inode for tracking user quota */
+	__le32	s_grp_quota_inum;	/* inode for tracking group quota */
+	__le32	s_reserved[110];        /* Padding to the end of the block */
 };
 
 #define EXT4_S_ERR_LEN (EXT4_S_ERR_END - EXT4_S_ERR_START)
@@ -1138,6 +1140,7 @@  struct ext4_sb_info {
 #ifdef CONFIG_QUOTA
 	char *s_qf_names[MAXQUOTAS];		/* Names of quota files with journalled quota */
 	int s_jquota_fmt;			/* Format of quota to use */
+	unsigned long s_qf_inums[MAXQUOTAS];	/* Quota file inodes */
 #endif
 	unsigned int s_want_extra_isize; /* New inodes should reserve # bytes */
 	struct rb_root system_blks;
@@ -1234,6 +1237,8 @@  static inline struct timespec ext4_current_time(struct inode *inode)
 static inline int ext4_valid_inum(struct super_block *sb, unsigned long ino)
 {
 	return ino == EXT4_ROOT_INO ||
+		ino == EXT4_USR_QUOTA_INO ||
+		ino == EXT4_GRP_QUOTA_INO ||
 		ino == EXT4_JOURNAL_INO ||
 		ino == EXT4_RESIZE_INO ||
 		(ino >= EXT4_FIRST_INO(sb) &&
@@ -1394,7 +1399,8 @@  static inline void ext4_clear_state_flags(struct ext4_inode_info *ei)
 					 EXT4_FEATURE_RO_COMPAT_DIR_NLINK | \
 					 EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE | \
 					 EXT4_FEATURE_RO_COMPAT_BTREE_DIR |\
-					 EXT4_FEATURE_RO_COMPAT_HUGE_FILE)
+					 EXT4_FEATURE_RO_COMPAT_HUGE_FILE| \
+					 EXT4_FEATURE_RO_COMPAT_QUOTA)
 
 /*
  * Default values for user and/or group using reserved blocks
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 9ea71aa..dd6590d 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1196,8 +1196,7 @@  static int ext4_acquire_dquot(struct dquot *dquot);
 static int ext4_release_dquot(struct dquot *dquot);
 static int ext4_mark_dquot_dirty(struct dquot *dquot);
 static int ext4_write_info(struct super_block *sb, int type);
-static int ext4_quota_on(struct super_block *sb, int type, int format_id,
-			 struct path *path);
+static int ext4_quota_on(struct super_block *sb, int type, int format_id);
 static int ext4_quota_off(struct super_block *sb, int type);
 static int ext4_quota_on_mount(struct super_block *sb, int type);
 static ssize_t ext4_quota_read(struct super_block *sb, int type, char *data,
@@ -1217,7 +1216,7 @@  static const struct dquot_operations ext4_quota_operations = {
 };
 
 static const struct quotactl_ops ext4_qctl_operations = {
-	.quota_on	= ext4_quota_on,
+	.quota_on_meta	= ext4_quota_on,
 	.quota_off	= ext4_quota_off,
 	.quota_sync	= dquot_quota_sync,
 	.get_info	= dquot_get_dqinfo,
@@ -3486,6 +3485,11 @@  static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 #ifdef CONFIG_QUOTA
 	sb->s_qcop = &ext4_qctl_operations;
 	sb->dq_op = &ext4_quota_operations;
+
+	if (EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_QUOTA)) {
+		sbi->s_qf_inums[USRQUOTA] = es->s_usr_quota_inum;
+		sbi->s_qf_inums[GRPQUOTA] = es->s_grp_quota_inum;
+	}
 #endif
 	memcpy(sb->s_uuid, es->s_uuid, sizeof(es->s_uuid));
 
@@ -3713,8 +3717,19 @@  no_journal:
 	} else
 		descr = "out journal";
 
-	ext4_msg(sb, KERN_INFO, "mounted filesystem with%s. "
-		 "Opts: %s%s%s", descr, sbi->s_es->s_mount_opts,
+#ifdef CONFIG_QUOTA
+	/* Enable quotas during mount. */
+	if (EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_QUOTA) &&
+	    !(sb->s_flags & MS_RDONLY)) {
+		ext4_quota_on(sb, USRQUOTA, QFMT_VFS_V1);
+		ext4_quota_on(sb, GRPQUOTA, QFMT_VFS_V1);
+	}
+#endif  /* CONFIG_QUOTA */
+
+	ext4_msg(sb, KERN_INFO, "mounted filesystem with%s. quota=%s. "
+		 "Opts: %s%s%s", descr,
+		 sb_any_quota_loaded(sb) ? "on" : "off",
+		 sbi->s_es->s_mount_opts,
 		 *sbi->s_es->s_mount_opts ? "; " : "", orig_data);
 
 	if (es->s_error_count)
@@ -4078,6 +4093,12 @@  static int ext4_commit_super(struct super_block *sb, int sync)
 	es->s_free_inodes_count =
 		cpu_to_le32(percpu_counter_sum_positive(
 				&EXT4_SB(sb)->s_freeinodes_counter));
+#ifdef CONFIG_QUOTA
+	if (EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_QUOTA)) {
+		es->s_usr_quota_inum = EXT4_SB(sb)->s_qf_inums[USRQUOTA];
+		es->s_grp_quota_inum = EXT4_SB(sb)->s_qf_inums[GRPQUOTA];
+	}
+#endif
 	sb->s_dirt = 0;
 	BUFFER_TRACE(sbh, "marking dirty");
 	mark_buffer_dirty(sbh);
@@ -4658,24 +4679,22 @@  static int ext4_quota_on_mount(struct super_block *sb, int type)
 /*
  * Standard function to be called on quota_on
  */
-static int ext4_quota_on(struct super_block *sb, int type, int format_id,
-			 struct path *path)
+static int ext4_quota_on(struct super_block *sb, int type, int format_id)
 {
 	int err;
+	struct inode *qf_inode;
 
-	if (!test_opt(sb, QUOTA))
+	if (!EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_QUOTA) ||
+	    !EXT4_SB(sb)->s_qf_inums[type])
 		return -EINVAL;
 
-	/* Quotafile not on the same filesystem? */
-	if (path->mnt->mnt_sb != sb)
-		return -EXDEV;
-	/* Journaling quota? */
-	if (EXT4_SB(sb)->s_qf_names[type]) {
-		/* Quotafile not in fs root? */
-		if (path->dentry->d_parent != sb->s_root)
-			ext4_msg(sb, KERN_WARNING,
-				"Quota file not on filesystem root. "
-				"Journaled quota will not work");
+	if (!EXT4_SB(sb)->s_qf_inums[type])
+		return -EINVAL;
+
+	qf_inode = ext4_iget(sb, EXT4_SB(sb)->s_qf_inums[type]);
+	if (IS_ERR(qf_inode)) {
+		EXT4_SB(sb)->s_qf_inums[type] = 0;
+		return PTR_ERR(qf_inode);
 	}
 
 	/*
@@ -4683,7 +4702,7 @@  static int ext4_quota_on(struct super_block *sb, int type, int format_id,
 	 * all updates to the file when we bypass pagecache...
 	 */
 	if (EXT4_SB(sb)->s_journal &&
-	    ext4_should_journal_data(path->dentry->d_inode)) {
+	    ext4_should_journal_data(qf_inode)) {
 		/*
 		 * We don't need to lock updates but journal_flush() could
 		 * otherwise be livelocked...
@@ -4695,7 +4714,11 @@  static int ext4_quota_on(struct super_block *sb, int type, int format_id,
 			return err;
 	}
 
-	return dquot_quota_on(sb, type, format_id, path);
+	err = dquot_enable(qf_inode, type, format_id,
+			   DQUOT_USAGE_ENABLED | DQUOT_LIMITS_ENABLED);
+	iput(qf_inode);
+
+	return err;
 }
 
 static int ext4_quota_off(struct super_block *sb, int type)
@@ -4703,6 +4726,10 @@  static int ext4_quota_off(struct super_block *sb, int type)
 	struct inode *inode = sb_dqopt(sb)->files[type];
 	handle_t *handle;
 
+	/* Do not allow turning quotas off. */
+	if (EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_QUOTA))
+		return -EINVAL;
+
 	/* Force all delayed allocation blocks to be allocated.
 	 * Caller already holds s_umount sem */
 	if (test_opt(sb, DELALLOC))