gfapi: handle graph switch (cwd, fds, locks)

- Migrate open fds to new graph
- Migrate locks held in open fd to new fd
- Refresh CWD, so resolution of relative paths happens on refreshed
  inode (on new graph).

Change-Id: I4b18083b9b290107ebda1f917fc85b635ab72fb4
BUG: 953694
Signed-off-by: Anand Avati <avati@redhat.com>
Reviewed-on: http://review.gluster.org/5059
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Raghavendra G <raghavendra@gluster.com>

1 files changed, 53 insertions, 4 deletions

diff --git a/api/src/glfs-internal.h b/api/src/glfs-internal.h
index d658ce2ae19..30ff599f2e6 100644
--- a/api/src/glfs-internal.h
+++ b/api/src/glfs-internal.h
@@ -33,6 +33,8 @@ struct glfs {
 	int                 err;
 
 	xlator_t           *active_subvol;
+	xlator_t           *next_subvol;
+	xlator_t           *old_subvol;
 
 	char               *oldvolfile;
 	ssize_t             oldvollen;
@@ -40,12 +42,17 @@ struct glfs {
 	inode_t            *cwd;
 
 	uint32_t            dev_id; /* Used to fill st_dev in struct stat */
+
+	struct list_head    openfds;
+
+	gf_boolean_t        migration_in_progress;
 };
 
 struct glfs_fd {
+	struct list_head   openfds;
 	struct glfs       *fs;
 	off_t              offset;
-	fd_t              *fd;
+	fd_t              *fd; /* Currently guared by @fs->mutex. TODO: per-glfd lock */
 	struct list_head   entries;
 	gf_dirent_t       *next;
 };
@@ -62,7 +69,11 @@ int glfs_resolve (struct glfs *fs, xlator_t *subvol, const char *path, loc_t *lo
 		  struct iatt *iatt, int reval);
 int glfs_lresolve (struct glfs *fs, xlator_t *subvol, const char *path, loc_t *loc,
 		   struct iatt *iatt, int reval);
-void glfs_first_lookup (xlator_t *subvol);
+fd_t *glfs_resolve_fd (struct glfs *fs, xlator_t *subvol, struct glfs_fd *glfd);
+
+fd_t *__glfs_migrate_fd (struct glfs *fs, xlator_t *subvol, struct glfs_fd *glfd);
+
+int glfs_first_lookup (xlator_t *subvol);
 
 static inline void
 __glfs_entry_fs (struct glfs *fs)
@@ -78,12 +89,50 @@ __glfs_entry_fd (struct glfs_fd *fd)
 }
 
 
+/*
+  By default all lock attempts from user context must
+  use glfs_lock() and glfs_unlock(). This allows
+  for a safe implementation of graph migration where
+  we can give up the mutex during syncop calls so
+  that bottom up calls (particularly CHILD_UP notify)
+  can do a mutex_lock() on @glfs without deadlocking
+  the filesystem
+*/
+static inline int
+glfs_lock (struct glfs *fs)
+{
+	pthread_mutex_lock (&fs->mutex);
+
+	while (!fs->init)
+		pthread_cond_wait (&fs->cond, &fs->mutex);
+
+	while (fs->migration_in_progress)
+		pthread_cond_wait (&fs->cond, &fs->mutex);
+
+	return 0;
+}
+
+
+static inline void
+glfs_unlock (struct glfs *fs)
+{
+	pthread_mutex_unlock (&fs->mutex);
+}
+
+
 void glfs_fd_destroy (struct glfs_fd *glfd);
 
 struct glfs_fd *glfs_fd_new (struct glfs *fs);
-
-xlator_t * glfs_fd_subvol (struct glfs_fd *glfd);
+void glfs_fd_bind (struct glfs_fd *glfd);
 
 xlator_t * glfs_active_subvol (struct glfs *fs);
+xlator_t * __glfs_active_subvol (struct glfs *fs);
+void glfs_subvol_done (struct glfs *fs, xlator_t *subvol);
+
+inode_t * glfs_refresh_inode (xlator_t *subvol, inode_t *inode);
+
+inode_t *glfs_cwd_get (struct glfs *fs);
+int glfs_cwd_set (struct glfs *fs, inode_t *inode);
+int __glfs_cwd_set (struct glfs *fs, inode_t *inode);
 
 #endif /* !_GLFS_INTERNAL_H */