ceph: use i_release_count to indicate dir's completeness

Current ceph code tracks directory's completeness in two places.
ceph_readdir() checks i_release_count to decide if it can set the
I_COMPLETE flag in i_ceph_flags. All other places check the I_COMPLETE
flag. This indirection introduces locking complexity.

This patch adds a new variable i_complete_count to ceph_inode_info.
Set i_release_count's value to it when marking a directory complete.
By comparing the two variables, we know if a directory is complete
Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>

fs/ceph/caps.c

@@ -490,7 +490,7 @@ static void __check_cap_issue(struct ceph_inode_info *ci, struct ceph_cap *cap,
 		ci->i_rdcache_gen++;
 
 	/*
-	 * if we are newly issued FILE_SHARED, clear I_COMPLETE; we
+	 * if we are newly issued FILE_SHARED, mark dir not complete; we
 	 * don't know what happened to this directory while we didn't
 	 * have the cap.
 	 */
@@ -499,7 +499,7 @@ static void __check_cap_issue(struct ceph_inode_info *ci, struct ceph_cap *cap,
 		ci->i_shared_gen++;
 		if (S_ISDIR(ci->vfs_inode.i_mode)) {
 			dout(" marking %p NOT complete\n", &ci->vfs_inode);
-			ci->i_ceph_flags &= ~CEPH_I_COMPLETE;
+			__ceph_dir_clear_complete(ci);
 		}
 	}
 }

fs/ceph/dir.c

@@ -107,7 +107,7 @@ static unsigned fpos_off(loff_t p)
  * falling back to a "normal" sync readdir if any dentries in the dir
  * are dropped.
  *
- * I_COMPLETE tells indicates we have all dentries in the dir.  It is
+ * Complete dir indicates that we have all dentries in the dir.  It is
  * defined IFF we hold CEPH_CAP_FILE_SHARED (which will be revoked by
  * the MDS if/when the directory is modified).
  */
@@ -198,8 +198,8 @@ static int __dcache_readdir(struct file *filp,
 	filp->f_pos++;
 
 	/* make sure a dentry wasn't dropped while we didn't have parent lock */
-	if (!ceph_i_test(dir, CEPH_I_COMPLETE)) {
-		dout(" lost I_COMPLETE on %p; falling back to mds\n", dir);
+	if (!ceph_dir_is_complete(dir)) {
+		dout(" lost dir complete on %p; falling back to mds\n", dir);
 		err = -EAGAIN;
 		goto out;
 	}
@@ -258,7 +258,7 @@ static int ceph_readdir(struct file *filp, void *dirent, filldir_t filldir)
 	if (filp->f_pos == 0) {
 		/* note dir version at start of readdir so we can tell
 		 * if any dentries get dropped */
-		fi->dir_release_count = ci->i_release_count;
+		fi->dir_release_count = atomic_read(&ci->i_release_count);
 
 		dout("readdir off 0 -> '.'\n");
 		if (filldir(dirent, ".", 1, ceph_make_fpos(0, 0),
@@ -284,7 +284,7 @@ static int ceph_readdir(struct file *filp, void *dirent, filldir_t filldir)
 	if ((filp->f_pos == 2 || fi->dentry) &&
 	    !ceph_test_mount_opt(fsc, NOASYNCREADDIR) &&
 	    ceph_snap(inode) != CEPH_SNAPDIR &&
-	    (ci->i_ceph_flags & CEPH_I_COMPLETE) &&
+	    __ceph_dir_is_complete(ci) &&
 	    __ceph_caps_issued_mask(ci, CEPH_CAP_FILE_SHARED, 1)) {
 		spin_unlock(&ci->i_ceph_lock);
 		err = __dcache_readdir(filp, dirent, filldir);
@@ -350,7 +350,8 @@ static int ceph_readdir(struct file *filp, void *dirent, filldir_t filldir)
 
 		if (!req->r_did_prepopulate) {
 			dout("readdir !did_prepopulate");
-			fi->dir_release_count--;    /* preclude I_COMPLETE */
+			/* preclude from marking dir complete */
+			fi->dir_release_count--;
 		}
 
 		/* note next offset and last dentry name */
@@ -428,9 +429,9 @@ static int ceph_readdir(struct file *filp, void *dirent, filldir_t filldir)
 	 * the complete dir contents in our cache.
 	 */
 	spin_lock(&ci->i_ceph_lock);
-	if (ci->i_release_count == fi->dir_release_count) {
+	if (atomic_read(&ci->i_release_count) == fi->dir_release_count) {
 		dout(" marking %p complete\n", inode);
-		ci->i_ceph_flags |= CEPH_I_COMPLETE;
+		__ceph_dir_set_complete(ci, fi->dir_release_count);
 		ci->i_max_offset = filp->f_pos;
 	}
 	spin_unlock(&ci->i_ceph_lock);
@@ -605,7 +606,7 @@ static struct dentry *ceph_lookup(struct inode *dir, struct dentry *dentry,
 			    fsc->mount_options->snapdir_name,
 			    dentry->d_name.len) &&
 		    !is_root_ceph_dentry(dir, dentry) &&
-		    (ci->i_ceph_flags & CEPH_I_COMPLETE) &&
+		    __ceph_dir_is_complete(ci) &&
 		    (__ceph_caps_issued_mask(ci, CEPH_CAP_FILE_SHARED, 1))) {
 			spin_unlock(&ci->i_ceph_lock);
 			dout(" dir %p complete, -ENOENT\n", dir);
@@ -909,7 +910,7 @@ static int ceph_rename(struct inode *old_dir, struct dentry *old_dentry,
 		 */
 
 		/* d_move screws up d_subdirs order */
-		ceph_i_clear(new_dir, CEPH_I_COMPLETE);
+		ceph_dir_clear_complete(new_dir);
 
 		d_move(old_dentry, new_dentry);
 
@@ -1079,7 +1080,7 @@ static void ceph_d_prune(struct dentry *dentry)
 	if (IS_ROOT(dentry))
 		return;
 
-	/* if we are not hashed, we don't affect I_COMPLETE */
+	/* if we are not hashed, we don't affect dir's completeness */
 	if (d_unhashed(dentry))
 		return;
 
@@ -1087,7 +1088,7 @@ static void ceph_d_prune(struct dentry *dentry)
 	 * we hold d_lock, so d_parent is stable, and d_fsdata is never
 	 * cleared until d_release
 	 */
-	ceph_i_clear(dentry->d_parent->d_inode, CEPH_I_COMPLETE);
+	ceph_dir_clear_complete(dentry->d_parent->d_inode);
 }
 
 /*

fs/ceph/inode.c

@@ -302,7 +302,8 @@ struct inode *ceph_alloc_inode(struct super_block *sb)
 	ci->i_version = 0;
 	ci->i_time_warp_seq = 0;
 	ci->i_ceph_flags = 0;
-	ci->i_release_count = 0;
+	atomic_set(&ci->i_release_count, 1);
+	atomic_set(&ci->i_complete_count, 0);
 	ci->i_symlink = NULL;
 
 	memset(&ci->i_dir_layout, 0, sizeof(ci->i_dir_layout));
@@ -721,9 +722,9 @@ static int fill_inode(struct inode *inode,
 	    ceph_snap(inode) == CEPH_NOSNAP &&
 	    (le32_to_cpu(info->cap.caps) & CEPH_CAP_FILE_SHARED) &&
 	    (issued & CEPH_CAP_FILE_EXCL) == 0 &&
-	    (ci->i_ceph_flags & CEPH_I_COMPLETE) == 0) {
+	    !__ceph_dir_is_complete(ci)) {
 		dout(" marking %p complete (empty)\n", inode);
-		ci->i_ceph_flags |= CEPH_I_COMPLETE;
+		__ceph_dir_set_complete(ci, atomic_read(&ci->i_release_count));
 		ci->i_max_offset = 2;
 	}
 no_change:
@@ -857,7 +858,7 @@ static void ceph_set_dentry_offset(struct dentry *dn)
 	di = ceph_dentry(dn);
 
 	spin_lock(&ci->i_ceph_lock);
-	if ((ceph_inode(inode)->i_ceph_flags & CEPH_I_COMPLETE) == 0) {
+	if (!__ceph_dir_is_complete(ci)) {
 		spin_unlock(&ci->i_ceph_lock);
 		return;
 	}
@@ -1061,8 +1062,8 @@ int ceph_fill_trace(struct super_block *sb, struct ceph_mds_request *req,
 			/*
 			 * d_move() puts the renamed dentry at the end of
 			 * d_subdirs.  We need to assign it an appropriate
-			 * directory offset so we can behave when holding
-			 * I_COMPLETE.
+			 * directory offset so we can behave when dir is
+			 * complete.
 			 */
 			ceph_set_dentry_offset(req->r_old_dentry);
 			dout("dn %p gets new offset %lld\n", req->r_old_dentry, 

fs/ceph/mds_client.c

@@ -2034,20 +2034,16 @@ int ceph_mdsc_do_request(struct ceph_mds_client *mdsc,
 }
 
 /*
- * Invalidate dir I_COMPLETE, dentry lease state on an aborted MDS
+ * Invalidate dir's completeness, dentry lease state on an aborted MDS
  * namespace request.
  */
 void ceph_invalidate_dir_request(struct ceph_mds_request *req)
 {
 	struct inode *inode = req->r_locked_dir;
-	struct ceph_inode_info *ci = ceph_inode(inode);
 
-	dout("invalidate_dir_request %p (I_COMPLETE, lease(s))\n", inode);
-	spin_lock(&ci->i_ceph_lock);
-	ci->i_ceph_flags &= ~CEPH_I_COMPLETE;
-	ci->i_release_count++;
-	spin_unlock(&ci->i_ceph_lock);
+	dout("invalidate_dir_request %p (complete, lease(s))\n", inode);
 
+	ceph_dir_clear_complete(inode);
 	if (req->r_dentry)
 		ceph_invalidate_dentry_lease(req->r_dentry);
 	if (req->r_old_dentry)

fs/ceph/super.h

@@ -244,7 +244,8 @@ struct ceph_inode_info {
 	u32 i_time_warp_seq;
 
 	unsigned i_ceph_flags;
-	unsigned long i_release_count;
+	atomic_t i_release_count;
+	atomic_t i_complete_count;
 
 	struct ceph_dir_layout i_dir_layout;
 	struct ceph_file_layout i_layout;
@@ -254,7 +255,7 @@ struct ceph_inode_info {
 	struct timespec i_rctime;
 	u64 i_rbytes, i_rfiles, i_rsubdirs;
 	u64 i_files, i_subdirs;
-	u64 i_max_offset;  /* largest readdir offset, set with I_COMPLETE */
+	u64 i_max_offset;  /* largest readdir offset, set with complete dir */
 
 	struct rb_root i_fragtree;
 	struct mutex i_fragtree_mutex;
@@ -419,38 +420,35 @@ static inline struct inode *ceph_find_inode(struct super_block *sb,
 /*
  * Ceph inode.
  */
-#define CEPH_I_COMPLETE  1  /* we have complete directory cached */
 #define CEPH_I_NODELAY   4  /* do not delay cap release */
 #define CEPH_I_FLUSH     8  /* do not delay flush of dirty metadata */
 #define CEPH_I_NOFLUSH  16  /* do not flush dirty caps */
 
-static inline void ceph_i_clear(struct inode *inode, unsigned mask)
+static inline void __ceph_dir_set_complete(struct ceph_inode_info *ci,
+					   int release_count)
 {
-	struct ceph_inode_info *ci = ceph_inode(inode);
-
-	spin_lock(&ci->i_ceph_lock);
-	ci->i_ceph_flags &= ~mask;
-	spin_unlock(&ci->i_ceph_lock);
+	atomic_set(&ci->i_complete_count, release_count);
 }
 
-static inline void ceph_i_set(struct inode *inode, unsigned mask)
+static inline void __ceph_dir_clear_complete(struct ceph_inode_info *ci)
 {
-	struct ceph_inode_info *ci = ceph_inode(inode);
+	atomic_inc(&ci->i_release_count);
+}
 
-	spin_lock(&ci->i_ceph_lock);
-	ci->i_ceph_flags |= mask;
-	spin_unlock(&ci->i_ceph_lock);
+static inline bool __ceph_dir_is_complete(struct ceph_inode_info *ci)
+{
+	return atomic_read(&ci->i_complete_count) ==
+		atomic_read(&ci->i_release_count);
 }
 
-static inline bool ceph_i_test(struct inode *inode, unsigned mask)
+static inline void ceph_dir_clear_complete(struct inode *inode)
 {
-	struct ceph_inode_info *ci = ceph_inode(inode);
-	bool r;
+	__ceph_dir_clear_complete(ceph_inode(inode));
+}
 
-	spin_lock(&ci->i_ceph_lock);
-	r = (ci->i_ceph_flags & mask) == mask;
-	spin_unlock(&ci->i_ceph_lock);
-	return r;
+static inline bool ceph_dir_is_complete(struct inode *inode)
+{
+	return __ceph_dir_is_complete(ceph_inode(inode));
 }
 
 
@@ -565,7 +563,7 @@ struct ceph_file_info {
 	u64 next_offset;       /* offset of next chunk (last_name's + 1) */
 	char *last_name;       /* last entry in previous chunk */
 	struct dentry *dentry; /* next dentry (for dcache readdir) */
-	unsigned long dir_release_count;
+	int dir_release_count;
 
 	/* used for -o dirstat read() on directory thing */
 	char *dir_info;