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>

5 files changed, 284 insertions, 2 deletions

diff --git a/fs/ceph/Makefile b/fs/ceph/Makefile
index 6a660e610be8..278e1172600d 100644
--- a/fs/ceph/Makefile
+++ b/fs/ceph/Makefile
@@ -6,7 +6,7 @@ ifneq ($(KERNELRELEASE),)
 
 obj-$(CONFIG_CEPH_FS) += ceph.o
 
-ceph-objs := super.o inode.o dir.o file.o addr.o ioctl.o \
+ceph-objs := super.o inode.o dir.o file.o locks.o addr.o ioctl.o \
         export.o caps.o snap.o xattr.o \
         messenger.o msgpool.o buffer.o pagelist.o \
         mds_client.o mdsmap.o \
diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index 5fe50ffa2deb..e850e63f9563 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -938,6 +938,8 @@ const struct file_operations ceph_file_fops = {
         .aio_write = ceph_aio_write,
         .mmap = ceph_mmap,
         .fsync = ceph_fsync,
+        .lock = ceph_lock,
+        .flock = ceph_flock,
         .splice_read = generic_file_splice_read,
         .splice_write = generic_file_splice_write,
         .unlocked_ioctl = ceph_ioctl,
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;
+}
diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index 615f720a819d..9f0833e1631a 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -3,6 +3,7 @@
 #include <linux/wait.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
+#include <linux/smp_lock.h>
 
 #include "mds_client.h"
 #include "mon_client.h"
@@ -2335,7 +2336,22 @@ static int encode_caps_cb(struct inode *inode, struct ceph_cap *cap,
         }
         spin_unlock(&inode->i_lock);
 
-        err = ceph_pagelist_append(pagelist, &rec, reclen);
+        if (recon_state->flock) {
+                int num_fcntl_locks, num_flock_locks;
+
+                lock_kernel();
+                ceph_count_locks(inode, &num_fcntl_locks, &num_flock_locks);
+                rec.v2.flock_len = (2*sizeof(u32) +
+                                    (num_fcntl_locks+num_flock_locks) *
+                                    sizeof(struct ceph_filelock));
+
+                err = ceph_pagelist_append(pagelist, &rec, reclen);
+                if (!err)
+                        err = ceph_encode_locks(inode, pagelist,
+                                                num_fcntl_locks,
+                                                num_flock_locks);
+                unlock_kernel();
+        }
 
 out:
         kfree(path);
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index 83f7cc5fab10..95adce441cc0 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -892,6 +892,14 @@ extern void ceph_debugfs_cleanup(void);
 extern int ceph_debugfs_client_init(struct ceph_client *client);
 extern void ceph_debugfs_client_cleanup(struct ceph_client *client);
 
+/* locks.c */
+extern int ceph_lock(struct file *file, int cmd, struct file_lock *fl);
+extern int ceph_flock(struct file *file, int cmd, struct file_lock *fl);
+extern void ceph_count_locks(struct inode *inode, int *p_num, int *f_num);
+extern int ceph_encode_locks(struct inode *i, struct ceph_pagelist *p,
+                             int p_locks, int f_locks);
+extern int lock_to_ceph_filelock(struct file_lock *fl, struct ceph_filelock *c);
+
 static inline struct inode *get_dentry_parent_inode(struct dentry *dentry)
 {
         if (dentry && dentry->d_parent)