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Subject[PATCH 10/56] quota: Introduce DQUOT_QUOTA_SYS_FILE flag
Date
From: Jan Kara <jack@suse.cz>

If filesystem can handle quota files as system files hidden from users, we can
skip a lot of cache invalidation, syncing, inode flags setting etc. when
turning quotas on, off and quota_sync. Allow filesystem to indicate that it is
hiding quota files from users by DQUOT_QUOTA_SYS_FILE flag.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>
---
fs/dquot.c | 45 ++++++++++++++++++++++++++++++---------------
fs/quota.c | 3 +++
include/linux/quota.h | 7 +++++++
3 files changed, 40 insertions(+), 15 deletions(-)

diff --git a/fs/dquot.c b/fs/dquot.c
index adf59ce..f4d6f7e 100644
--- a/fs/dquot.c
+++ b/fs/dquot.c
@@ -1631,6 +1631,11 @@ int vfs_quota_disable(struct super_block *sb, int type, unsigned int flags)
dqopt->ops[cnt] = NULL;
}
mutex_unlock(&dqopt->dqonoff_mutex);
+
+ /* Skip syncing and setting flags if quota files are hidden */
+ if (dqopt->flags & DQUOT_QUOTA_SYS_FILE)
+ goto put_inodes;
+
/* Sync the superblock so that buffers with quota data are written to
* disk (and so userspace sees correct data afterwards). */
if (sb->s_op->sync_fs)
@@ -1655,6 +1660,12 @@ int vfs_quota_disable(struct super_block *sb, int type, unsigned int flags)
mark_inode_dirty(toputinode[cnt]);
}
mutex_unlock(&dqopt->dqonoff_mutex);
+ }
+ if (sb->s_bdev)
+ invalidate_bdev(sb->s_bdev);
+put_inodes:
+ for (cnt = 0; cnt < MAXQUOTAS; cnt++)
+ if (toputinode[cnt]) {
/* On remount RO, we keep the inode pointer so that we
* can reenable quota on the subsequent remount RW. We
* have to check 'flags' variable and not use sb_has_
@@ -1667,8 +1678,6 @@ int vfs_quota_disable(struct super_block *sb, int type, unsigned int flags)
else if (!toputinode[cnt]->i_nlink)
ret = -EBUSY;
}
- if (sb->s_bdev)
- invalidate_bdev(sb->s_bdev);
return ret;
}

@@ -1715,25 +1724,31 @@ static int vfs_load_quota_inode(struct inode *inode, int type, int format_id,
goto out_fmt;
}

- /* As we bypass the pagecache we must now flush the inode so that
- * we see all the changes from userspace... */
- write_inode_now(inode, 1);
- /* And now flush the block cache so that kernel sees the changes */
- invalidate_bdev(sb->s_bdev);
+ if (!(dqopt->flags & DQUOT_QUOTA_SYS_FILE)) {
+ /* As we bypass the pagecache we must now flush the inode so
+ * that we see all the changes from userspace... */
+ write_inode_now(inode, 1);
+ /* And now flush the block cache so that kernel sees the
+ * changes */
+ invalidate_bdev(sb->s_bdev);
+ }
mutex_lock(&inode->i_mutex);
mutex_lock(&dqopt->dqonoff_mutex);
if (sb_has_quota_loaded(sb, type)) {
error = -EBUSY;
goto out_lock;
}
- /* We don't want quota and atime on quota files (deadlocks possible)
- * Also nobody should write to the file - we use special IO operations
- * which ignore the immutable bit. */
- down_write(&dqopt->dqptr_sem);
- oldflags = inode->i_flags & (S_NOATIME | S_IMMUTABLE | S_NOQUOTA);
- inode->i_flags |= S_NOQUOTA | S_NOATIME | S_IMMUTABLE;
- up_write(&dqopt->dqptr_sem);
- sb->dq_op->drop(inode);
+
+ if (!(dqopt->flags & DQUOT_QUOTA_SYS_FILE)) {
+ /* We don't want quota and atime on quota files (deadlocks
+ * possible) Also nobody should write to the file - we use
+ * special IO operations which ignore the immutable bit. */
+ down_write(&dqopt->dqptr_sem);
+ oldflags = inode->i_flags & (S_NOATIME | S_IMMUTABLE | S_NOQUOTA);
+ inode->i_flags |= S_NOQUOTA | S_NOATIME | S_IMMUTABLE;
+ up_write(&dqopt->dqptr_sem);
+ sb->dq_op->drop(inode);
+ }

error = -EIO;
dqopt->files[type] = igrab(inode);
diff --git a/fs/quota.c b/fs/quota.c
index a8026f1..2c6ea78 100644
--- a/fs/quota.c
+++ b/fs/quota.c
@@ -160,6 +160,9 @@ static void quota_sync_sb(struct super_block *sb, int type)
int cnt;

sb->s_qcop->quota_sync(sb, type);
+
+ if (sb_dqopt(sb)->flags & DQUOT_QUOTA_SYS_FILE)
+ return;
/* This is not very clever (and fast) but currently I don't know about
* any other simple way of getting quota data to disk and we must get
* them there for userspace to be visible... */
diff --git a/include/linux/quota.h b/include/linux/quota.h
index 93717ab..80b8807 100644
--- a/include/linux/quota.h
+++ b/include/linux/quota.h
@@ -332,6 +332,13 @@ enum {
#define DQUOT_SUSPENDED (1 << _DQUOT_SUSPENDED)
#define DQUOT_STATE_FLAGS (DQUOT_USAGE_ENABLED | DQUOT_LIMITS_ENABLED | \
DQUOT_SUSPENDED)
+/* Other quota flags */
+#define DQUOT_QUOTA_SYS_FILE (1 << 6) /* Quota file is a special
+ * system file and user cannot
+ * touch it. Filesystem is
+ * responsible for setting
+ * S_NOQUOTA, S_NOATIME flags
+ */

static inline unsigned int dquot_state_flag(unsigned int flags, int type)
{
--
1.5.6


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