ocfs2: implement delayed dropping of last dquot reference
We cannot drop last dquot reference from downconvert thread as that
creates the following deadlock:
NODE 1 NODE2
holds dentry lock for 'foo'
holds inode lock for GLOBAL_BITMAP_SYSTEM_INODE
dquot_initialize(bar)
ocfs2_dquot_acquire()
ocfs2_inode_lock(USER_QUOTA_SYSTEM_INODE)
...
downconvert thread (triggered from another
node or a different process from NODE2)
ocfs2_dentry_post_unlock()
...
iput(foo)
ocfs2_evict_inode(foo)
ocfs2_clear_inode(foo)
dquot_drop(inode)
...
ocfs2_dquot_release()
ocfs2_inode_lock(USER_QUOTA_SYSTEM_INODE)
- blocks
finds we need more space in
quota file
...
ocfs2_extend_no_holes()
ocfs2_inode_lock(GLOBAL_BITMAP_SYSTEM_INODE)
- deadlocks waiting for
downconvert thread
We solve the problem by postponing dropping of the last dquot reference to
a workqueue if it happens from the downconvert thread.
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Mark Fasheh <mfasheh@suse.de>
Reviewed-by: Srinivas Eeda <srinivas.eeda@oracle.com>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/ocfs2/quota.h b/fs/ocfs2/quota.h
index d5ab56c..f266d67 100644
--- a/fs/ocfs2/quota.h
+++ b/fs/ocfs2/quota.h
@@ -28,6 +28,7 @@
unsigned int dq_use_count; /* Number of nodes having reference to this entry in global quota file */
s64 dq_origspace; /* Last globally synced space usage */
s64 dq_originodes; /* Last globally synced inode usage */
+ struct llist_node list; /* Member of list of dquots to drop */
};
/* Description of one chunk to recover in memory */
@@ -110,6 +111,7 @@
int ocfs2_create_local_dquot(struct dquot *dquot);
int ocfs2_local_release_dquot(handle_t *handle, struct dquot *dquot);
int ocfs2_local_write_dquot(struct dquot *dquot);
+void ocfs2_drop_dquot_refs(struct work_struct *work);
extern const struct dquot_operations ocfs2_quota_operations;
extern struct quota_format_type ocfs2_quota_format;