ceph: add flock/fcntl lock support

Implement flock inode operation to support advisory file locking.  All
lock/unlock operations are synchronous with the MDS.  Lock state is
sent when reconnecting to a recovering MDS to restore the shared lock
state.

Signed-off-by: Greg Farnum <gregf@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>

1 files changed, 256 insertions, 0 deletions

diff --git a/fs/ceph/locks.c b/fs/ceph/locks.c
new file mode 100644
index 000000000000..ae85af06454f
--- /dev/null
+++ b/fs/ceph/locks.c
@@ -0,0 +1,256 @@
+#include "ceph_debug.h"
+
+#include <linux/file.h>
+#include <linux/namei.h>
+
+#include "super.h"
+#include "mds_client.h"
+#include "pagelist.h"
+
+/**
+ * Implement fcntl and flock locking functions.
+ */
+static int ceph_lock_message(u8 lock_type, u16 operation, struct file *file,
+			     u64 pid, u64 pid_ns,
+			     int cmd, u64 start, u64 length, u8 wait)
+{
+	struct inode *inode = file->f_dentry->d_inode;
+	struct ceph_mds_client *mdsc =
+		&ceph_sb_to_client(inode->i_sb)->mdsc;
+	struct ceph_mds_request *req;
+	int err;
+
+	req = ceph_mdsc_create_request(mdsc, operation, USE_AUTH_MDS);
+	if (IS_ERR(req))
+		return PTR_ERR(req);
+	req->r_inode = igrab(inode);
+
+	dout("ceph_lock_message: rule: %d, op: %d, pid: %llu, start: %llu, "
+	     "length: %llu, wait: %d, type`: %d", (int)lock_type,
+	     (int)operation, pid, start, length, wait, cmd);
+
+	req->r_args.filelock_change.rule = lock_type;
+	req->r_args.filelock_change.type = cmd;
+	req->r_args.filelock_change.pid = cpu_to_le64(pid);
+	/* This should be adjusted, but I'm not sure if
+	   namespaces actually get id numbers*/
+	req->r_args.filelock_change.pid_namespace =
+		cpu_to_le64((u64)pid_ns);
+	req->r_args.filelock_change.start = cpu_to_le64(start);
+	req->r_args.filelock_change.length = cpu_to_le64(length);
+	req->r_args.filelock_change.wait = wait;
+
+	err = ceph_mdsc_do_request(mdsc, inode, req);
+	ceph_mdsc_put_request(req);
+	dout("ceph_lock_message: rule: %d, op: %d, pid: %llu, start: %llu, "
+	     "length: %llu, wait: %d, type`: %d err code %d", (int)lock_type,
+	     (int)operation, pid, start, length, wait, cmd, err);
+	return err;
+}
+
+/**
+ * Attempt to set an fcntl lock.
+ * For now, this just goes away to the server. Later it may be more awesome.
+ */
+int ceph_lock(struct file *file, int cmd, struct file_lock *fl)
+{
+	u64 length;
+	u8 lock_cmd;
+	int err;
+	u8 wait = 0;
+	u16 op = CEPH_MDS_OP_SETFILELOCK;
+
+	fl->fl_nspid = get_pid(task_tgid(current));
+	dout("ceph_lock, fl_pid:%d", fl->fl_pid);
+
+	/* set wait bit as appropriate, then make command as Ceph expects it*/
+	if (F_SETLKW == cmd)
+		wait = 1;
+	if (F_GETLK == cmd)
+		op = CEPH_MDS_OP_GETFILELOCK;
+
+	if (F_RDLCK == fl->fl_type)
+		lock_cmd = CEPH_LOCK_SHARED;
+	else if (F_WRLCK == fl->fl_type)
+		lock_cmd = CEPH_LOCK_EXCL;
+	else
+		lock_cmd = CEPH_LOCK_UNLOCK;
+
+	if (LLONG_MAX == fl->fl_end)
+		length = 0;
+	else
+		length = fl->fl_end - fl->fl_start + 1;
+
+	err = ceph_lock_message(CEPH_LOCK_FCNTL, op, file,
+				(u64)fl->fl_pid, (u64)fl->fl_nspid,
+				lock_cmd, fl->fl_start,
+				length, wait);
+	if (!err) {
+		dout("mds locked, locking locally");
+		err = posix_lock_file(file, fl, NULL);
+		if (err && (CEPH_MDS_OP_SETFILELOCK == op)) {
+			/* undo! This should only happen if the kernel detects
+			 * local deadlock. */
+			ceph_lock_message(CEPH_LOCK_FCNTL, op, file,
+					  (u64)fl->fl_pid, (u64)fl->fl_nspid,
+					  CEPH_LOCK_UNLOCK, fl->fl_start,
+					  length, 0);
+			dout("got %d on posix_lock_file, undid lock", err);
+		}
+	} else {
+		dout("mds returned error code %d", err);
+	}
+	return err;
+}
+
+int ceph_flock(struct file *file, int cmd, struct file_lock *fl)
+{
+	u64 length;
+	u8 lock_cmd;
+	int err;
+	u8 wait = 1;
+
+	fl->fl_nspid = get_pid(task_tgid(current));
+	dout("ceph_flock, fl_pid:%d", fl->fl_pid);
+
+	/* set wait bit, then clear it out of cmd*/
+	if (cmd & LOCK_NB)
+		wait = 0;
+	cmd = cmd & (LOCK_SH | LOCK_EX | LOCK_UN);
+	/* set command sequence that Ceph wants to see:
+	   shared lock, exclusive lock, or unlock */
+	if (LOCK_SH == cmd)
+		lock_cmd = CEPH_LOCK_SHARED;
+	else if (LOCK_EX == cmd)
+		lock_cmd = CEPH_LOCK_EXCL;
+	else
+		lock_cmd = CEPH_LOCK_UNLOCK;
+	/* mds requires start and length rather than start and end */
+	if (LLONG_MAX == fl->fl_end)
+		length = 0;
+	else
+		length = fl->fl_end - fl->fl_start + 1;
+
+	err = ceph_lock_message(CEPH_LOCK_FLOCK, CEPH_MDS_OP_SETFILELOCK,
+				file, (u64)fl->fl_pid, (u64)fl->fl_nspid,
+				lock_cmd, fl->fl_start,
+				length, wait);
+	if (!err) {
+		err = flock_lock_file_wait(file, fl);
+		if (err) {
+			ceph_lock_message(CEPH_LOCK_FLOCK,
+					  CEPH_MDS_OP_SETFILELOCK,
+					  file, (u64)fl->fl_pid,
+					  (u64)fl->fl_nspid,
+					  CEPH_LOCK_UNLOCK, fl->fl_start,
+					  length, 0);
+			dout("got %d on flock_lock_file_wait, undid lock", err);
+		}
+	} else {
+		dout("mds error code %d", err);
+	}
+	return err;
+}
+
+/**
+ * Must be called with BKL already held. Fills in the passed
+ * counter variables, so you can prepare pagelist metadata before calling
+ * ceph_encode_locks.
+ */
+void ceph_count_locks(struct inode *inode, int *fcntl_count, int *flock_count)
+{
+	struct file_lock *lock;
+
+	*fcntl_count = 0;
+	*flock_count = 0;
+
+	for (lock = inode->i_flock; lock != NULL; lock = lock->fl_next) {
+		if (lock->fl_flags & FL_POSIX)
+			++(*fcntl_count);
+		else if (lock->fl_flags & FL_FLOCK)
+			++(*flock_count);
+	}
+	dout("counted %d flock locks and %d fcntl locks",
+	     *flock_count, *fcntl_count);
+}
+
+/**
+ * Encode the flock and fcntl locks for the given inode into the pagelist.
+ * Format is: #fcntl locks, sequential fcntl locks, #flock locks,
+ * sequential flock locks.
+ * Must be called with BLK already held, and the lock numbers should have
+ * been gathered under the same lock holding window.
+ */
+int ceph_encode_locks(struct inode *inode, struct ceph_pagelist *pagelist,
+		      int num_fcntl_locks, int num_flock_locks)
+{
+	struct file_lock *lock;
+	struct ceph_filelock cephlock;
+	int err = 0;
+
+	dout("encoding %d flock and %d fcntl locks", num_flock_locks,
+	     num_fcntl_locks);
+	err = ceph_pagelist_append(pagelist, &num_fcntl_locks, sizeof(u32));
+	if (err)
+		goto fail;
+	for (lock = inode->i_flock; lock != NULL; lock = lock->fl_next) {
+		if (lock->fl_flags & FL_POSIX) {
+			err = lock_to_ceph_filelock(lock, &cephlock);
+			if (err)
+				goto fail;
+			err = ceph_pagelist_append(pagelist, &cephlock,
+					   sizeof(struct ceph_filelock));
+		}
+		if (err)
+			goto fail;
+	}
+
+	err = ceph_pagelist_append(pagelist, &num_flock_locks, sizeof(u32));
+	if (err)
+		goto fail;
+	for (lock = inode->i_flock; lock != NULL; lock = lock->fl_next) {
+		if (lock->fl_flags & FL_FLOCK) {
+			err = lock_to_ceph_filelock(lock, &cephlock);
+			if (err)
+				goto fail;
+			err = ceph_pagelist_append(pagelist, &cephlock,
+					   sizeof(struct ceph_filelock));
+		}
+		if (err)
+			goto fail;
+	}
+fail:
+	return err;
+}
+
+/*
+ * Given a pointer to a lock, convert it to a ceph filelock
+ */
+int lock_to_ceph_filelock(struct file_lock *lock,
+			  struct ceph_filelock *cephlock)
+{
+	int err = 0;
+
+	cephlock->start = cpu_to_le64(lock->fl_start);
+	cephlock->length = cpu_to_le64(lock->fl_end - lock->fl_start + 1);
+	cephlock->client = cpu_to_le64(0);
+	cephlock->pid = cpu_to_le64(lock->fl_pid);
+	cephlock->pid_namespace = cpu_to_le64((u64)lock->fl_nspid);
+
+	switch (lock->fl_type) {
+	case F_RDLCK:
+		cephlock->type = CEPH_LOCK_SHARED;
+		break;
+	case F_WRLCK:
+		cephlock->type = CEPH_LOCK_EXCL;
+		break;
+	case F_UNLCK:
+		cephlock->type = CEPH_LOCK_UNLOCK;
+		break;
+	default:
+		dout("Have unknown lock type %d", lock->fl_type);
+		err = -EINVAL;
+	}
+
+	return err;
+}