[PATCH] ext3: journalled quotas

From: Jan Kara <jack@ucw.cz>

Journalled quota support for ext3: The patch consists of two parts - ext3
changes and changes in generic quota code.  The main idea of the changes is
that a transaction is always started before any operation which changes quota
file and dirtifying of the quota causes its write to disk.  These two changes
assure that quota change is journalled into the same transaction as the file
change and hence after journal replay quota is consistent with the filesystem
state.  As during journal replay inodes from orphan list are deleted/truncated
we have to do quota_on before the replay of the orphan list - this problem is
solved by additional mount options to ext3 with quota file names and format.

Some changes in generic code were also needed to assure that quota structure
in file is always allocated and so ordinary quota operations (like
adding/deleting a block/inode) need only a few blocks from the transaction.

1 files changed, 31 insertions, 10 deletions

diff --git a/include/linux/quotaops.h b/include/linux/quotaops.h
index e5a9e6bed751..9db474dcafd5 100644
--- a/include/linux/quotaops.h
+++ b/include/linux/quotaops.h
@@ -22,16 +22,31 @@
  */
 extern void sync_dquots(struct super_block *sb, int type);
 
-extern void dquot_initialize(struct inode *inode, int type);
-extern void dquot_drop(struct inode *inode);
-
-extern int  dquot_alloc_space(struct inode *inode, qsize_t number, int prealloc);
-extern int  dquot_alloc_inode(const struct inode *inode, unsigned long number);
-
-extern void dquot_free_space(struct inode *inode, qsize_t number);
-extern void dquot_free_inode(const struct inode *inode, unsigned long number);
-
-extern int  dquot_transfer(struct inode *inode, struct iattr *iattr);
+extern int dquot_initialize(struct inode *inode, int type);
+extern int dquot_drop(struct inode *inode);
+
+extern int dquot_alloc_space(struct inode *inode, qsize_t number, int prealloc);
+extern int dquot_alloc_inode(const struct inode *inode, unsigned long number);
+
+extern int dquot_free_space(struct inode *inode, qsize_t number);
+extern int dquot_free_inode(const struct inode *inode, unsigned long number);
+
+extern int dquot_transfer(struct inode *inode, struct iattr *iattr);
+extern int dquot_commit(struct dquot *dquot);
+extern int dquot_acquire(struct dquot *dquot);
+extern int dquot_release(struct dquot *dquot);
+extern int dquot_commit_info(struct super_block *sb, int type);
+extern int dquot_mark_dquot_dirty(struct dquot *dquot);
+
+extern int vfs_quota_on(struct super_block *sb, int type, int format_id, char *path);
+extern int vfs_quota_on_mount(int type, int format_id, struct dentry *dentry);
+extern int vfs_quota_off(struct super_block *sb, int type);
+#define vfs_quota_off_mount(sb, type) vfs_quota_off(sb, type)
+extern int vfs_quota_sync(struct super_block *sb, int type);
+extern int vfs_get_dqinfo(struct super_block *sb, int type, struct if_dqinfo *ii);
+extern int vfs_set_dqinfo(struct super_block *sb, int type, struct if_dqinfo *ii);
+extern int vfs_get_dqblk(struct super_block *sb, int type, qid_t id, struct if_dqblk *di);
+extern int vfs_set_dqblk(struct super_block *sb, int type, qid_t id, struct if_dqblk *di);
 
 /*
  * Operations supported for diskquotas.
@@ -42,6 +57,8 @@ extern struct quotactl_ops vfs_quotactl_ops;
 #define sb_dquot_ops (&dquot_operations)
 #define sb_quotactl_ops (&vfs_quotactl_ops)
 
+/* It is better to call this function outside of any transaction as it might
+ * need a lot of space in journal for dquot structure allocation. */
 static __inline__ void DQUOT_INIT(struct inode *inode)
 {
 	BUG_ON(!inode->i_sb);
@@ -49,6 +66,7 @@ static __inline__ void DQUOT_INIT(struct inode *inode)
 		inode->i_sb->dq_op->initialize(inode, -1);
 }
 
+/* The same as with DQUOT_INIT */
 static __inline__ void DQUOT_DROP(struct inode *inode)
 {
 	if (IS_QUOTAINIT(inode)) {
@@ -57,6 +75,8 @@ static __inline__ void DQUOT_DROP(struct inode *inode)
 	}
 }
 
+/* The following allocation/freeing/transfer functions *must* be called inside
+ * a transaction (deadlocks possible otherwise) */
 static __inline__ int DQUOT_PREALLOC_SPACE_NODIRTY(struct inode *inode, qsize_t nr)
 {
 	if (sb_any_quota_enabled(inode->i_sb)) {
@@ -137,6 +157,7 @@ static __inline__ int DQUOT_TRANSFER(struct inode *inode, struct iattr *iattr)
 	return 0;
 }
 
+/* The following two functions cannot be called inside a transaction */
 #define DQUOT_SYNC(sb)	sync_dquots(sb, -1)
 
 static __inline__ int DQUOT_OFF(struct super_block *sb)