fs/ceph/locks.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 #include <linux/ceph/ceph_debug.h>

 #include <linux/file.h>
 #include <linux/namei.h>
 #include <linux/random.h>

 #include "super.h"
 #include "mds_client.h"
 #include <linux/ceph/pagelist.h>

 static u64 lock_secret;
 static int ceph_lock_wait_for_completion(struct ceph_mds_client *mdsc,
                                          struct ceph_mds_request *req);

 static inline u64 secure_addr(void *addr)
 {
 	u64 v = lock_secret ^ (u64)(unsigned long)addr;
 	/*
 	 * Set the most significant bit, so that MDS knows the 'owner'
 	 * is sufficient to identify the owner of lock. (old code uses
 	 * both 'owner' and 'pid')
 	 */
 	v |= (1ULL << 63);
 	return v;
 }

 void __init ceph_flock_init(void)
 {
 	get_random_bytes(&lock_secret, sizeof(lock_secret));
 }

 static void ceph_fl_copy_lock(struct file_lock *dst, struct file_lock *src)
 {
 	struct ceph_file_info *fi = dst->fl_file->private_data;
 	struct inode *inode = file_inode(dst->fl_file);
 	atomic_inc(&ceph_inode(inode)->i_filelock_ref);
 	atomic_inc(&fi->num_locks);
 }

 static void ceph_fl_release_lock(struct file_lock *fl)
 {
 	struct ceph_file_info *fi = fl->fl_file->private_data;
 	struct inode *inode = file_inode(fl->fl_file);
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	atomic_dec(&fi->num_locks);
 	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 = {
 	.fl_copy_lock = ceph_fl_copy_lock,
 	.fl_release_private = ceph_fl_release_lock,
 };

 /*
  * Implement fcntl and flock locking functions.
  */
 static int ceph_lock_message(u8 lock_type, u16 operation, struct inode *inode,
 			     int cmd, u8 wait, struct file_lock *fl)
 {
 	struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(inode->i_sb);
 	struct ceph_mds_request *req;
 	int err;
 	u64 length = 0;
 	u64 owner;

 	if (operation == CEPH_MDS_OP_SETFILELOCK) {
 		/*
 		 * increasing i_filelock_ref closes race window between
 		 * handling request reply and adding file_lock struct to
 		 * inode. Otherwise, auth caps may get trimmed in the
 		 * window. Caller function will decrease the counter.
 		 */
 		fl->fl_ops = &ceph_fl_lock_ops;
 		fl->fl_ops->fl_copy_lock(fl, NULL);
 	}

 	if (operation != CEPH_MDS_OP_SETFILELOCK || cmd == CEPH_LOCK_UNLOCK)
 		wait = 0;

 	req = ceph_mdsc_create_request(mdsc, operation, USE_AUTH_MDS);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 	req->r_inode = inode;
 	ihold(inode);
 	req->r_num_caps = 1;

 	/* 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;

 	owner = secure_addr(fl->fl_owner);

 	dout("ceph_lock_message: rule: %d, op: %d, owner: %llx, pid: %llu, "
 	     "start: %llu, length: %llu, wait: %d, type: %d\n", (int)lock_type,
 	     (int)operation, owner, (u64)fl->fl_pid, fl->fl_start, length,
 	     wait, fl->fl_type);

 	req->r_args.filelock_change.rule = lock_type;
 	req->r_args.filelock_change.type = cmd;
 	req->r_args.filelock_change.owner = cpu_to_le64(owner);
 	req->r_args.filelock_change.pid = cpu_to_le64((u64)fl->fl_pid);
 	req->r_args.filelock_change.start = cpu_to_le64(fl->fl_start);
 	req->r_args.filelock_change.length = cpu_to_le64(length);
 	req->r_args.filelock_change.wait = wait;

 	if (wait)
 		req->r_wait_for_completion = ceph_lock_wait_for_completion;

 	err = ceph_mdsc_do_request(mdsc, inode, req);
 	if (!err && operation == CEPH_MDS_OP_GETFILELOCK) {
 		fl->fl_pid = -le64_to_cpu(req->r_reply_info.filelock_reply->pid);
 		if (CEPH_LOCK_SHARED == req->r_reply_info.filelock_reply->type)
 			fl->fl_type = F_RDLCK;
 		else if (CEPH_LOCK_EXCL == req->r_reply_info.filelock_reply->type)
 			fl->fl_type = F_WRLCK;
 		else
 			fl->fl_type = F_UNLCK;

 		fl->fl_start = le64_to_cpu(req->r_reply_info.filelock_reply->start);
 		length = le64_to_cpu(req->r_reply_info.filelock_reply->start) +
 						 le64_to_cpu(req->r_reply_info.filelock_reply->length);
 		if (length >= 1)
 			fl->fl_end = length -1;
 		else
 			fl->fl_end = 0;

 	}
 	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\n", (int)lock_type,
 	     (int)operation, (u64)fl->fl_pid, fl->fl_start,
 	     length, wait, fl->fl_type, err);
 	return err;
 }

 static int ceph_lock_wait_for_completion(struct ceph_mds_client *mdsc,
                                          struct ceph_mds_request *req)
 {
 	struct ceph_mds_request *intr_req;
 	struct inode *inode = req->r_inode;
 	int err, lock_type;

 	BUG_ON(req->r_op != CEPH_MDS_OP_SETFILELOCK);
 	if (req->r_args.filelock_change.rule == CEPH_LOCK_FCNTL)
 		lock_type = CEPH_LOCK_FCNTL_INTR;
 	else if (req->r_args.filelock_change.rule == CEPH_LOCK_FLOCK)
 		lock_type = CEPH_LOCK_FLOCK_INTR;
 	else
 		BUG_ON(1);
 	BUG_ON(req->r_args.filelock_change.type == CEPH_LOCK_UNLOCK);

 	err = wait_for_completion_interruptible(&req->r_completion);
 	if (!err)
 		return 0;

 	dout("ceph_lock_wait_for_completion: request %llu was interrupted\n",
 	     req->r_tid);

 	mutex_lock(&mdsc->mutex);
 	if (test_bit(CEPH_MDS_R_GOT_RESULT, &req->r_req_flags)) {
 		err = 0;
 	} else {
 		/*
 		 * ensure we aren't running concurrently with
 		 * ceph_fill_trace or ceph_readdir_prepopulate, which
 		 * rely on locks (dir mutex) held by our caller.
 		 */
 		mutex_lock(&req->r_fill_mutex);
 		req->r_err = err;
 		set_bit(CEPH_MDS_R_ABORTED, &req->r_req_flags);
 		mutex_unlock(&req->r_fill_mutex);

 		if (!req->r_session) {
 			// haven't sent the request
 			err = 0;
 		}
 	}
 	mutex_unlock(&mdsc->mutex);
 	if (!err)
 		return 0;

 	intr_req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_SETFILELOCK,
 					    USE_AUTH_MDS);
 	if (IS_ERR(intr_req))
 		return PTR_ERR(intr_req);

 	intr_req->r_inode = inode;
 	ihold(inode);
 	intr_req->r_num_caps = 1;

 	intr_req->r_args.filelock_change = req->r_args.filelock_change;
 	intr_req->r_args.filelock_change.rule = lock_type;
 	intr_req->r_args.filelock_change.type = CEPH_LOCK_UNLOCK;

 	err = ceph_mdsc_do_request(mdsc, inode, intr_req);
 	ceph_mdsc_put_request(intr_req);

 	if (err && err != -ERESTARTSYS)
 		return err;

 	wait_for_completion_killable(&req->r_safe_completion);
 	return 0;
 }

 static int try_unlock_file(struct file *file, struct file_lock *fl)
 {
 	int err;
 	unsigned int orig_flags = fl->fl_flags;
 	fl->fl_flags |= FL_EXISTS;
 	err = locks_lock_file_wait(file, fl);
 	fl->fl_flags = orig_flags;
 	if (err == -ENOENT) {
 		if (!(orig_flags & FL_EXISTS))
 			err = 0;
 		return err;
 	}
 	return 1;
 }

 /*
  * 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)
 {
 	struct inode *inode = file_inode(file);
 	struct ceph_inode_info *ci = ceph_inode(inode);
 	int err = 0;
 	u16 op = CEPH_MDS_OP_SETFILELOCK;
 	u8 wait = 0;
 	u8 lock_cmd;

 	if (!(fl->fl_flags & FL_POSIX))
 		return -ENOLCK;
 	/* No mandatory locks */
 	if (__mandatory_lock(file->f_mapping->host) && fl->fl_type != F_UNLCK)
 		return -ENOLCK;

 	dout("ceph_lock, fl_owner: %p\n", fl->fl_owner);

 	/* set wait bit as appropriate, then make command as Ceph expects it*/
 	if (IS_GETLK(cmd))
 		op = CEPH_MDS_OP_GETFILELOCK;
 	else if (IS_SETLKW(cmd))
 		wait = 1;

 	spin_lock(&ci->i_ceph_lock);
 	if (ci->i_ceph_flags & CEPH_I_ERROR_FILELOCK) {
 		err = -EIO;
 	}
 	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)
 		lock_cmd = CEPH_LOCK_SHARED;
 	else if (F_WRLCK == fl->fl_type)
 		lock_cmd = CEPH_LOCK_EXCL;
 	else
 		lock_cmd = CEPH_LOCK_UNLOCK;

 	if (op == CEPH_MDS_OP_SETFILELOCK && F_UNLCK == fl->fl_type) {
 		err = try_unlock_file(file, fl);
 		if (err <= 0)
 			return err;
 	}

 	err = ceph_lock_message(CEPH_LOCK_FCNTL, op, inode, lock_cmd, wait, fl);
 	if (!err) {
 		if (op == CEPH_MDS_OP_SETFILELOCK && F_UNLCK != fl->fl_type) {
 			dout("mds locked, locking locally\n");
 			err = posix_lock_file(file, fl, NULL);
 			if (err) {
 				/* undo! This should only happen if
 				 * the kernel detects local
 				 * deadlock. */
 				ceph_lock_message(CEPH_LOCK_FCNTL, op, inode,
 						  CEPH_LOCK_UNLOCK, 0, fl);
 				dout("got %d on posix_lock_file, undid lock\n",
 				     err);
 			}
 		}
 	}
 	return err;
 }

 int ceph_flock(struct file *file, int cmd, struct file_lock *fl)
 {
 	struct inode *inode = file_inode(file);
 	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;
 	/* No mandatory locks */
 	if (fl->fl_type & LOCK_MAND)
 		return -EOPNOTSUPP;

 	dout("ceph_flock, fl_file: %p\n", fl->fl_file);

 	spin_lock(&ci->i_ceph_lock);
 	if (ci->i_ceph_flags & CEPH_I_ERROR_FILELOCK) {
 		err = -EIO;
 	}
 	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;

 	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 (F_UNLCK == fl->fl_type) {
 		err = try_unlock_file(file, fl);
 		if (err <= 0)
 			return err;
 	}

 	err = ceph_lock_message(CEPH_LOCK_FLOCK, CEPH_MDS_OP_SETFILELOCK,
 				inode, lock_cmd, wait, fl);
 	if (!err && F_UNLCK != fl->fl_type) {
 		err = locks_lock_file_wait(file, fl);
 		if (err) {
 			ceph_lock_message(CEPH_LOCK_FLOCK,
 					  CEPH_MDS_OP_SETFILELOCK,
 					  inode, CEPH_LOCK_UNLOCK, 0, fl);
 			dout("got %d on locks_lock_file_wait, undid lock\n", err);
 		}
 	}
 	return err;
 }

 /*
  * 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;
 	struct file_lock_context *ctx;

 	*fcntl_count = 0;
 	*flock_count = 0;

 	ctx = inode->i_flctx;
 	if (ctx) {
 		spin_lock(&ctx->flc_lock);
 		list_for_each_entry(lock, &ctx->flc_posix, fl_list)
 			++(*fcntl_count);
 		list_for_each_entry(lock, &ctx->flc_flock, fl_list)
 			++(*flock_count);
 		spin_unlock(&ctx->flc_lock);
 	}
 	dout("counted %d flock locks and %d fcntl locks\n",
 	     *flock_count, *fcntl_count);
 }

 /*
  * Given a pointer to a lock, convert it to a ceph filelock
  */
 static 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((u64)lock->fl_pid);
 	cephlock->owner = cpu_to_le64(secure_addr(lock->fl_owner));

 	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\n", lock->fl_type);
 		err = -EINVAL;
 	}

 	return err;
 }

 /*
  * Encode the flock and fcntl locks for the given inode into the ceph_filelock
  * array. Must be called with inode->i_lock already held.
  * If we encounter more of a specific lock type than expected, return -ENOSPC.
  */
 int ceph_encode_locks_to_buffer(struct inode *inode,
 				struct ceph_filelock *flocks,
 				int num_fcntl_locks, int num_flock_locks)
 {
 	struct file_lock *lock;
 	struct file_lock_context *ctx = inode->i_flctx;
 	int err = 0;
 	int seen_fcntl = 0;
 	int seen_flock = 0;
 	int l = 0;

 	dout("encoding %d flock and %d fcntl locks\n", num_flock_locks,
 	     num_fcntl_locks);

 	if (!ctx)
 		return 0;

 	spin_lock(&ctx->flc_lock);
 	list_for_each_entry(lock, &ctx->flc_posix, fl_list) {
 		++seen_fcntl;
 		if (seen_fcntl > num_fcntl_locks) {
 			err = -ENOSPC;
 			goto fail;
 		}
 		err = lock_to_ceph_filelock(lock, &flocks[l]);
 		if (err)
 			goto fail;
 		++l;
 	}
 	list_for_each_entry(lock, &ctx->flc_flock, fl_list) {
 		++seen_flock;
 		if (seen_flock > num_flock_locks) {
 			err = -ENOSPC;
 			goto fail;
 		}
 		err = lock_to_ceph_filelock(lock, &flocks[l]);
 		if (err)
 			goto fail;
 		++l;
 	}
 fail:
 	spin_unlock(&ctx->flc_lock);
 	return err;
 }

 /*
  * Copy the encoded flock and fcntl locks into the pagelist.
  * Format is: #fcntl locks, sequential fcntl locks, #flock locks,
  * sequential flock locks.
  * Returns zero on success.
  */
 int ceph_locks_to_pagelist(struct ceph_filelock *flocks,
 			   struct ceph_pagelist *pagelist,
 			   int num_fcntl_locks, int num_flock_locks)
 {
 	int err = 0;
 	__le32 nlocks;

 	nlocks = cpu_to_le32(num_fcntl_locks);
 	err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
 	if (err)
 		goto out_fail;

 	if (num_fcntl_locks > 0) {
 		err = ceph_pagelist_append(pagelist, flocks,
 					   num_fcntl_locks * sizeof(*flocks));
 		if (err)
 			goto out_fail;
 	}

 	nlocks = cpu_to_le32(num_flock_locks);
 	err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
 	if (err)
 		goto out_fail;

 	if (num_flock_locks > 0) {
 		err = ceph_pagelist_append(pagelist, &flocks[num_fcntl_locks],
 					   num_flock_locks * sizeof(*flocks));
 	}
 out_fail:
 	return err;
 }
	// SPDX-License-Identifier: GPL-2.0
	#include <linux/ceph/ceph_debug.h>

	#include <linux/file.h>
	#include <linux/namei.h>
	#include <linux/random.h>

	#include "super.h"
	#include "mds_client.h"
	#include <linux/ceph/pagelist.h>

	static u64 lock_secret;
	static int ceph_lock_wait_for_completion(struct ceph_mds_client *mdsc,
	struct ceph_mds_request *req);

	static inline u64 secure_addr(void *addr)
	{
	u64 v = lock_secret ^ (u64)(unsigned long)addr;
	/*
	* Set the most significant bit, so that MDS knows the 'owner'
	* is sufficient to identify the owner of lock. (old code uses
	* both 'owner' and 'pid')
	*/
	v \|= (1ULL << 63);
	return v;
	}

	void __init ceph_flock_init(void)
	{
	get_random_bytes(&lock_secret, sizeof(lock_secret));
	}

	static void ceph_fl_copy_lock(struct file_lock dst, struct file_lock src)
	{
	struct ceph_file_info *fi = dst->fl_file->private_data;
	struct inode *inode = file_inode(dst->fl_file);
	atomic_inc(&ceph_inode(inode)->i_filelock_ref);
	atomic_inc(&fi->num_locks);
	}

	static void ceph_fl_release_lock(struct file_lock *fl)
	{
	struct ceph_file_info *fi = fl->fl_file->private_data;
	struct inode *inode = file_inode(fl->fl_file);
	struct ceph_inode_info *ci = ceph_inode(inode);
	atomic_dec(&fi->num_locks);
	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 = {
	.fl_copy_lock = ceph_fl_copy_lock,
	.fl_release_private = ceph_fl_release_lock,
	};

	/*
	* Implement fcntl and flock locking functions.
	*/
	static int ceph_lock_message(u8 lock_type, u16 operation, struct inode *inode,
	int cmd, u8 wait, struct file_lock *fl)
	{
	struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(inode->i_sb);
	struct ceph_mds_request *req;
	int err;
	u64 length = 0;
	u64 owner;

	if (operation == CEPH_MDS_OP_SETFILELOCK) {
	/*
	* increasing i_filelock_ref closes race window between
	* handling request reply and adding file_lock struct to
	* inode. Otherwise, auth caps may get trimmed in the
	* window. Caller function will decrease the counter.
	*/
	fl->fl_ops = &ceph_fl_lock_ops;
	fl->fl_ops->fl_copy_lock(fl, NULL);
	}

	if (operation != CEPH_MDS_OP_SETFILELOCK \|\| cmd == CEPH_LOCK_UNLOCK)
	wait = 0;

	req = ceph_mdsc_create_request(mdsc, operation, USE_AUTH_MDS);
	if (IS_ERR(req))
	return PTR_ERR(req);
	req->r_inode = inode;
	ihold(inode);
	req->r_num_caps = 1;

	/* 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;

	owner = secure_addr(fl->fl_owner);

	dout("ceph_lock_message: rule: %d, op: %d, owner: %llx, pid: %llu, "
	"start: %llu, length: %llu, wait: %d, type: %d\n", (int)lock_type,
	(int)operation, owner, (u64)fl->fl_pid, fl->fl_start, length,
	wait, fl->fl_type);

	req->r_args.filelock_change.rule = lock_type;
	req->r_args.filelock_change.type = cmd;
	req->r_args.filelock_change.owner = cpu_to_le64(owner);
	req->r_args.filelock_change.pid = cpu_to_le64((u64)fl->fl_pid);
	req->r_args.filelock_change.start = cpu_to_le64(fl->fl_start);
	req->r_args.filelock_change.length = cpu_to_le64(length);
	req->r_args.filelock_change.wait = wait;

	if (wait)
	req->r_wait_for_completion = ceph_lock_wait_for_completion;

	err = ceph_mdsc_do_request(mdsc, inode, req);
	if (!err && operation == CEPH_MDS_OP_GETFILELOCK) {
	fl->fl_pid = -le64_to_cpu(req->r_reply_info.filelock_reply->pid);
	if (CEPH_LOCK_SHARED == req->r_reply_info.filelock_reply->type)
	fl->fl_type = F_RDLCK;
	else if (CEPH_LOCK_EXCL == req->r_reply_info.filelock_reply->type)
	fl->fl_type = F_WRLCK;
	else
	fl->fl_type = F_UNLCK;

	fl->fl_start = le64_to_cpu(req->r_reply_info.filelock_reply->start);
	length = le64_to_cpu(req->r_reply_info.filelock_reply->start) +
	le64_to_cpu(req->r_reply_info.filelock_reply->length);
	if (length >= 1)
	fl->fl_end = length -1;
	else
	fl->fl_end = 0;

	}
	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\n", (int)lock_type,
	(int)operation, (u64)fl->fl_pid, fl->fl_start,
	length, wait, fl->fl_type, err);
	return err;
	}

	static int ceph_lock_wait_for_completion(struct ceph_mds_client *mdsc,
	struct ceph_mds_request *req)
	{
	struct ceph_mds_request *intr_req;
	struct inode *inode = req->r_inode;
	int err, lock_type;

	BUG_ON(req->r_op != CEPH_MDS_OP_SETFILELOCK);
	if (req->r_args.filelock_change.rule == CEPH_LOCK_FCNTL)
	lock_type = CEPH_LOCK_FCNTL_INTR;
	else if (req->r_args.filelock_change.rule == CEPH_LOCK_FLOCK)
	lock_type = CEPH_LOCK_FLOCK_INTR;
	else
	BUG_ON(1);
	BUG_ON(req->r_args.filelock_change.type == CEPH_LOCK_UNLOCK);

	err = wait_for_completion_interruptible(&req->r_completion);
	if (!err)
	return 0;

	dout("ceph_lock_wait_for_completion: request %llu was interrupted\n",
	req->r_tid);

	mutex_lock(&mdsc->mutex);
	if (test_bit(CEPH_MDS_R_GOT_RESULT, &req->r_req_flags)) {
	err = 0;
	} else {
	/*
	* ensure we aren't running concurrently with
	* ceph_fill_trace or ceph_readdir_prepopulate, which
	* rely on locks (dir mutex) held by our caller.
	*/
	mutex_lock(&req->r_fill_mutex);
	req->r_err = err;
	set_bit(CEPH_MDS_R_ABORTED, &req->r_req_flags);
	mutex_unlock(&req->r_fill_mutex);

	if (!req->r_session) {
	// haven't sent the request
	err = 0;
	}
	}
	mutex_unlock(&mdsc->mutex);
	if (!err)
	return 0;

	intr_req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_SETFILELOCK,
	USE_AUTH_MDS);
	if (IS_ERR(intr_req))
	return PTR_ERR(intr_req);

	intr_req->r_inode = inode;
	ihold(inode);
	intr_req->r_num_caps = 1;

	intr_req->r_args.filelock_change = req->r_args.filelock_change;
	intr_req->r_args.filelock_change.rule = lock_type;
	intr_req->r_args.filelock_change.type = CEPH_LOCK_UNLOCK;

	err = ceph_mdsc_do_request(mdsc, inode, intr_req);
	ceph_mdsc_put_request(intr_req);

	if (err && err != -ERESTARTSYS)
	return err;

	wait_for_completion_killable(&req->r_safe_completion);
	return 0;
	}

	static int try_unlock_file(struct file file, struct file_lock fl)
	{
	int err;
	unsigned int orig_flags = fl->fl_flags;
	fl->fl_flags \|= FL_EXISTS;
	err = locks_lock_file_wait(file, fl);
	fl->fl_flags = orig_flags;
	if (err == -ENOENT) {
	if (!(orig_flags & FL_EXISTS))
	err = 0;
	return err;
	}
	return 1;
	}

	/*
	* 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)
	{
	struct inode *inode = file_inode(file);
	struct ceph_inode_info *ci = ceph_inode(inode);
	int err = 0;
	u16 op = CEPH_MDS_OP_SETFILELOCK;
	u8 wait = 0;
	u8 lock_cmd;

	if (!(fl->fl_flags & FL_POSIX))
	return -ENOLCK;
	/* No mandatory locks */
	if (__mandatory_lock(file->f_mapping->host) && fl->fl_type != F_UNLCK)
	return -ENOLCK;

	dout("ceph_lock, fl_owner: %p\n", fl->fl_owner);

	/* set wait bit as appropriate, then make command as Ceph expects it*/
	if (IS_GETLK(cmd))
	op = CEPH_MDS_OP_GETFILELOCK;
	else if (IS_SETLKW(cmd))
	wait = 1;

	spin_lock(&ci->i_ceph_lock);
	if (ci->i_ceph_flags & CEPH_I_ERROR_FILELOCK) {
	err = -EIO;
	}
	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)
	lock_cmd = CEPH_LOCK_SHARED;
	else if (F_WRLCK == fl->fl_type)
	lock_cmd = CEPH_LOCK_EXCL;
	else
	lock_cmd = CEPH_LOCK_UNLOCK;

	if (op == CEPH_MDS_OP_SETFILELOCK && F_UNLCK == fl->fl_type) {
	err = try_unlock_file(file, fl);
	if (err <= 0)
	return err;
	}

	err = ceph_lock_message(CEPH_LOCK_FCNTL, op, inode, lock_cmd, wait, fl);
	if (!err) {
	if (op == CEPH_MDS_OP_SETFILELOCK && F_UNLCK != fl->fl_type) {
	dout("mds locked, locking locally\n");
	err = posix_lock_file(file, fl, NULL);
	if (err) {
	/* undo! This should only happen if
	* the kernel detects local
	* deadlock. */
	ceph_lock_message(CEPH_LOCK_FCNTL, op, inode,
	CEPH_LOCK_UNLOCK, 0, fl);
	dout("got %d on posix_lock_file, undid lock\n",
	err);
	}
	}
	}
	return err;
	}

	int ceph_flock(struct file file, int cmd, struct file_lock fl)
	{
	struct inode *inode = file_inode(file);
	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;
	/* No mandatory locks */
	if (fl->fl_type & LOCK_MAND)
	return -EOPNOTSUPP;

	dout("ceph_flock, fl_file: %p\n", fl->fl_file);

	spin_lock(&ci->i_ceph_lock);
	if (ci->i_ceph_flags & CEPH_I_ERROR_FILELOCK) {
	err = -EIO;
	}
	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;

	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 (F_UNLCK == fl->fl_type) {
	err = try_unlock_file(file, fl);
	if (err <= 0)
	return err;
	}

	err = ceph_lock_message(CEPH_LOCK_FLOCK, CEPH_MDS_OP_SETFILELOCK,
	inode, lock_cmd, wait, fl);
	if (!err && F_UNLCK != fl->fl_type) {
	err = locks_lock_file_wait(file, fl);
	if (err) {
	ceph_lock_message(CEPH_LOCK_FLOCK,
	CEPH_MDS_OP_SETFILELOCK,
	inode, CEPH_LOCK_UNLOCK, 0, fl);
	dout("got %d on locks_lock_file_wait, undid lock\n", err);
	}
	}
	return err;
	}

	/*
	* 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;
	struct file_lock_context *ctx;

	*fcntl_count = 0;
	*flock_count = 0;

	ctx = inode->i_flctx;
	if (ctx) {
	spin_lock(&ctx->flc_lock);
	list_for_each_entry(lock, &ctx->flc_posix, fl_list)
	++(*fcntl_count);
	list_for_each_entry(lock, &ctx->flc_flock, fl_list)
	++(*flock_count);
	spin_unlock(&ctx->flc_lock);
	}
	dout("counted %d flock locks and %d fcntl locks\n",
	flock_count, fcntl_count);
	}

	/*
	* Given a pointer to a lock, convert it to a ceph filelock
	*/
	static 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((u64)lock->fl_pid);
	cephlock->owner = cpu_to_le64(secure_addr(lock->fl_owner));

	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\n", lock->fl_type);
	err = -EINVAL;
	}

	return err;
	}

	/*
	* Encode the flock and fcntl locks for the given inode into the ceph_filelock
	* array. Must be called with inode->i_lock already held.
	* If we encounter more of a specific lock type than expected, return -ENOSPC.
	*/
	int ceph_encode_locks_to_buffer(struct inode *inode,
	struct ceph_filelock *flocks,
	int num_fcntl_locks, int num_flock_locks)
	{
	struct file_lock *lock;
	struct file_lock_context *ctx = inode->i_flctx;
	int err = 0;
	int seen_fcntl = 0;
	int seen_flock = 0;
	int l = 0;

	dout("encoding %d flock and %d fcntl locks\n", num_flock_locks,
	num_fcntl_locks);

	if (!ctx)
	return 0;

	spin_lock(&ctx->flc_lock);
	list_for_each_entry(lock, &ctx->flc_posix, fl_list) {
	++seen_fcntl;
	if (seen_fcntl > num_fcntl_locks) {
	err = -ENOSPC;
	goto fail;
	}
	err = lock_to_ceph_filelock(lock, &flocks[l]);
	if (err)
	goto fail;
	++l;
	}
	list_for_each_entry(lock, &ctx->flc_flock, fl_list) {
	++seen_flock;
	if (seen_flock > num_flock_locks) {
	err = -ENOSPC;
	goto fail;
	}
	err = lock_to_ceph_filelock(lock, &flocks[l]);
	if (err)
	goto fail;
	++l;
	}
	fail:
	spin_unlock(&ctx->flc_lock);
	return err;
	}

	/*
	* Copy the encoded flock and fcntl locks into the pagelist.
	* Format is: #fcntl locks, sequential fcntl locks, #flock locks,
	* sequential flock locks.
	* Returns zero on success.
	*/
	int ceph_locks_to_pagelist(struct ceph_filelock *flocks,
	struct ceph_pagelist *pagelist,
	int num_fcntl_locks, int num_flock_locks)
	{
	int err = 0;
	__le32 nlocks;

	nlocks = cpu_to_le32(num_fcntl_locks);
	err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
	if (err)
	goto out_fail;

	if (num_fcntl_locks > 0) {
	err = ceph_pagelist_append(pagelist, flocks,
	num_fcntl_locks * sizeof(*flocks));
	if (err)
	goto out_fail;
	}

	nlocks = cpu_to_le32(num_flock_locks);
	err = ceph_pagelist_append(pagelist, &nlocks, sizeof(nlocks));
	if (err)
	goto out_fail;

	if (num_flock_locks > 0) {
	err = ceph_pagelist_append(pagelist, &flocks[num_fcntl_locks],
	num_flock_locks * sizeof(*flocks));
	}
	out_fail:
	return err;
	}