ceph: handle 'session get evicted while there are file locks'

When session get evicted, all file locks associated with the session
get released remotely by mds. File locks tracked by kernel become
stale. In this situation, set an error flag on inode. The flag makes
further file locks return -EIO.

Another option to handle this situation is cleanup file locks tracked
kernel. I do not choose it because it is inconvenient to notify user
program about the error.

Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

1 files changed, 40 insertions, 12 deletions

diff --git a/fs/ceph/locks.c b/fs/ceph/locks.c
index aaea82076849..9e66f69ee8a5 100644
--- a/fs/ceph/locks.c
+++ b/fs/ceph/locks.c
@@ -39,7 +39,13 @@ static void ceph_fl_copy_lock(struct file_lock *dst, struct file_lock *src)
 static void ceph_fl_release_lock(struct file_lock *fl)
 {
 	struct inode *inode = file_inode(fl->fl_file);
-	atomic_dec(&ceph_inode(inode)->i_filelock_ref);
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	if (atomic_dec_and_test(&ci->i_filelock_ref)) {
+		/* clear error when all locks are released */
+		spin_lock(&ci->i_ceph_lock);
+		ci->i_ceph_flags &= ~CEPH_I_ERROR_FILELOCK;
+		spin_unlock(&ci->i_ceph_lock);
+	}
 }
 
 static const struct file_lock_operations ceph_fl_lock_ops = {
@@ -208,10 +214,11 @@ static int ceph_lock_wait_for_completion(struct ceph_mds_client *mdsc,
 int ceph_lock(struct file *file, int cmd, struct file_lock *fl)
 {
 	struct inode *inode = file_inode(file);
-	int err;
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	int err = 0;
 	u16 op = CEPH_MDS_OP_SETFILELOCK;
-	u8 lock_cmd;
 	u8 wait = 0;
+	u8 lock_cmd;
 
 	if (!(fl->fl_flags & FL_POSIX))
 		return -ENOLCK;
@@ -227,7 +234,10 @@ int ceph_lock(struct file *file, int cmd, struct file_lock *fl)
 	else if (IS_SETLKW(cmd))
 		wait = 1;
 
-	if (op == CEPH_MDS_OP_SETFILELOCK) {
+	spin_lock(&ci->i_ceph_lock);
+	if (ci->i_ceph_flags & CEPH_I_ERROR_FILELOCK) {
+		err = -EIO;
+	} else if (op == CEPH_MDS_OP_SETFILELOCK) {
 		/*
 		 * increasing i_filelock_ref closes race window between
 		 * handling request reply and adding file_lock struct to
@@ -235,7 +245,13 @@ int ceph_lock(struct file *file, int cmd, struct file_lock *fl)
 		 * window. Caller function will decrease the counter.
 		 */
 		fl->fl_ops = &ceph_fl_lock_ops;
-		atomic_inc(&ceph_inode(inode)->i_filelock_ref);
+		atomic_inc(&ci->i_filelock_ref);
+	}
+	spin_unlock(&ci->i_ceph_lock);
+	if (err < 0) {
+		if (op == CEPH_MDS_OP_SETFILELOCK && F_UNLCK == fl->fl_type)
+			posix_lock_file(file, fl, NULL);
+		return err;
 	}
 
 	if (F_RDLCK == fl->fl_type)
@@ -247,10 +263,10 @@ int ceph_lock(struct file *file, int cmd, struct file_lock *fl)
 
 	err = ceph_lock_message(CEPH_LOCK_FCNTL, op, inode, lock_cmd, wait, fl);
 	if (!err) {
-		if (op != CEPH_MDS_OP_GETFILELOCK) {
+		if (op == CEPH_MDS_OP_SETFILELOCK) {
 			dout("mds locked, locking locally");
 			err = posix_lock_file(file, fl, NULL);
-			if (err && (CEPH_MDS_OP_SETFILELOCK == op)) {
+			if (err) {
 				/* undo! This should only happen if
 				 * the kernel detects local
 				 * deadlock. */
@@ -267,9 +283,10 @@ int ceph_lock(struct file *file, int cmd, struct file_lock *fl)
 int ceph_flock(struct file *file, int cmd, struct file_lock *fl)
 {
 	struct inode *inode = file_inode(file);
-	int err;
-	u8 lock_cmd;
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	int err = 0;
 	u8 wait = 0;
+	u8 lock_cmd;
 
 	if (!(fl->fl_flags & FL_FLOCK))
 		return -ENOLCK;
@@ -279,9 +296,20 @@ int ceph_flock(struct file *file, int cmd, struct file_lock *fl)
 
 	dout("ceph_flock, fl_file: %p", fl->fl_file);
 
-	/* see comment in ceph_lock */
-	fl->fl_ops = &ceph_fl_lock_ops;
-	atomic_inc(&ceph_inode(inode)->i_filelock_ref);
+	spin_lock(&ci->i_ceph_lock);
+	if (ci->i_ceph_flags & CEPH_I_ERROR_FILELOCK) {
+		err = -EIO;
+	} else {
+		/* see comment in ceph_lock */
+		fl->fl_ops = &ceph_fl_lock_ops;
+		atomic_inc(&ci->i_filelock_ref);
+	}
+	spin_unlock(&ci->i_ceph_lock);
+	if (err < 0) {
+		if (F_UNLCK == fl->fl_type)
+			locks_lock_file_wait(file, fl);
+		return err;
+	}
 
 	if (IS_SETLKW(cmd))
 		wait = 1;