1 files changed, 165 insertions, 129 deletions

diff --git a/fs/locks.c b/fs/locks.c
index b286539d547a..3b0d05dcd7c1 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -60,7 +60,7 @@
  *
  *  Initial implementation of mandatory locks. SunOS turned out to be
  *  a rotten model, so I implemented the "obvious" semantics.
- *  See 'Documentation/mandatory.txt' for details.
+ *  See 'Documentation/filesystems/mandatory-locking.txt' for details.
  *  Andy Walker (andy@lysaker.kvaerner.no), April 06, 1996.
  *
  *  Don't allow mandatory locks on mmap()'ed files. Added simple functions to
@@ -133,6 +133,20 @@
 #define IS_FLOCK(fl)	(fl->fl_flags & FL_FLOCK)
 #define IS_LEASE(fl)	(fl->fl_flags & FL_LEASE)
 
+static bool lease_breaking(struct file_lock *fl)
+{
+	return fl->fl_flags & (FL_UNLOCK_PENDING | FL_DOWNGRADE_PENDING);
+}
+
+static int target_leasetype(struct file_lock *fl)
+{
+	if (fl->fl_flags & FL_UNLOCK_PENDING)
+		return F_UNLCK;
+	if (fl->fl_flags & FL_DOWNGRADE_PENDING)
+		return F_RDLCK;
+	return fl->fl_type;
+}
+
 int leases_enable = 1;
 int lease_break_time = 45;
 
@@ -160,26 +174,20 @@ EXPORT_SYMBOL_GPL(unlock_flocks);
 
 static struct kmem_cache *filelock_cache __read_mostly;
 
-static void locks_init_lock_always(struct file_lock *fl)
+static void locks_init_lock_heads(struct file_lock *fl)
 {
-	fl->fl_next = NULL;
-	fl->fl_fasync = NULL;
-	fl->fl_owner = NULL;
-	fl->fl_pid = 0;
-	fl->fl_nspid = NULL;
-	fl->fl_file = NULL;
-	fl->fl_flags = 0;
-	fl->fl_type = 0;
-	fl->fl_start = fl->fl_end = 0;
+	INIT_LIST_HEAD(&fl->fl_link);
+	INIT_LIST_HEAD(&fl->fl_block);
+	init_waitqueue_head(&fl->fl_wait);
 }
 
 /* Allocate an empty lock structure. */
 struct file_lock *locks_alloc_lock(void)
 {
-	struct file_lock *fl = kmem_cache_alloc(filelock_cache, GFP_KERNEL);
+	struct file_lock *fl = kmem_cache_zalloc(filelock_cache, GFP_KERNEL);
 
 	if (fl)
-		locks_init_lock_always(fl);
+		locks_init_lock_heads(fl);
 
 	return fl;
 }
@@ -193,8 +201,8 @@ void locks_release_private(struct file_lock *fl)
 		fl->fl_ops = NULL;
 	}
 	if (fl->fl_lmops) {
-		if (fl->fl_lmops->fl_release_private)
-			fl->fl_lmops->fl_release_private(fl);
+		if (fl->fl_lmops->lm_release_private)
+			fl->fl_lmops->lm_release_private(fl);
 		fl->fl_lmops = NULL;
 	}
 
@@ -215,27 +223,12 @@ EXPORT_SYMBOL(locks_free_lock);
 
 void locks_init_lock(struct file_lock *fl)
 {
-	INIT_LIST_HEAD(&fl->fl_link);
-	INIT_LIST_HEAD(&fl->fl_block);
-	init_waitqueue_head(&fl->fl_wait);
-	fl->fl_ops = NULL;
-	fl->fl_lmops = NULL;
-	locks_init_lock_always(fl);
+	memset(fl, 0, sizeof(struct file_lock));
+	locks_init_lock_heads(fl);
 }
 
 EXPORT_SYMBOL(locks_init_lock);
 
-/*
- * Initialises the fields of the file lock which are invariant for
- * free file_locks.
- */
-static void init_once(void *foo)
-{
-	struct file_lock *lock = (struct file_lock *) foo;
-
-	locks_init_lock(lock);
-}
-
 static void locks_copy_private(struct file_lock *new, struct file_lock *fl)
 {
 	if (fl->fl_ops) {
@@ -444,9 +437,9 @@ static void lease_release_private_callback(struct file_lock *fl)
 }
 
 static const struct lock_manager_operations lease_manager_ops = {
-	.fl_break = lease_break_callback,
-	.fl_release_private = lease_release_private_callback,
-	.fl_change = lease_modify,
+	.lm_break = lease_break_callback,
+	.lm_release_private = lease_release_private_callback,
+	.lm_change = lease_modify,
 };
 
 /*
@@ -499,9 +492,9 @@ static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2)
  */
 static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
 {
-	if (fl1->fl_lmops && fl1->fl_lmops->fl_compare_owner)
+	if (fl1->fl_lmops && fl1->fl_lmops->lm_compare_owner)
 		return fl2->fl_lmops == fl1->fl_lmops &&
-			fl1->fl_lmops->fl_compare_owner(fl1, fl2);
+			fl1->fl_lmops->lm_compare_owner(fl1, fl2);
 	return fl1->fl_owner == fl2->fl_owner;
 }
 
@@ -551,8 +544,8 @@ static void locks_wake_up_blocks(struct file_lock *blocker)
 		waiter = list_first_entry(&blocker->fl_block,
 				struct file_lock, fl_block);
 		__locks_delete_block(waiter);
-		if (waiter->fl_lmops && waiter->fl_lmops->fl_notify)
-			waiter->fl_lmops->fl_notify(waiter);
+		if (waiter->fl_lmops && waiter->fl_lmops->lm_notify)
+			waiter->fl_lmops->lm_notify(waiter);
 		else
 			wake_up(&waiter->fl_wait);
 	}
@@ -1140,6 +1133,17 @@ int locks_mandatory_area(int read_write, struct inode *inode,
 
 EXPORT_SYMBOL(locks_mandatory_area);
 
+static void lease_clear_pending(struct file_lock *fl, int arg)
+{
+	switch (arg) {
+	case F_UNLCK:
+		fl->fl_flags &= ~FL_UNLOCK_PENDING;
+		/* fall through: */
+	case F_RDLCK:
+		fl->fl_flags &= ~FL_DOWNGRADE_PENDING;
+	}
+}
+
 /* We already had a lease on this file; just change its type */
 int lease_modify(struct file_lock **before, int arg)
 {
@@ -1148,6 +1152,7 @@ int lease_modify(struct file_lock **before, int arg)
 
 	if (error)
 		return error;
+	lease_clear_pending(fl, arg);
 	locks_wake_up_blocks(fl);
 	if (arg == F_UNLCK)
 		locks_delete_lock(before);
@@ -1156,19 +1161,25 @@ int lease_modify(struct file_lock **before, int arg)
 
 EXPORT_SYMBOL(lease_modify);
 
+static bool past_time(unsigned long then)
+{
+	if (!then)
+		/* 0 is a special value meaning "this never expires": */
+		return false;
+	return time_after(jiffies, then);
+}
+
 static void time_out_leases(struct inode *inode)
 {
 	struct file_lock **before;
 	struct file_lock *fl;
 
 	before = &inode->i_flock;
-	while ((fl = *before) && IS_LEASE(fl) && (fl->fl_type & F_INPROGRESS)) {
-		if ((fl->fl_break_time == 0)
-				|| time_before(jiffies, fl->fl_break_time)) {
-			before = &fl->fl_next;
-			continue;
-		}
-		lease_modify(before, fl->fl_type & ~F_INPROGRESS);
+	while ((fl = *before) && IS_LEASE(fl) && lease_breaking(fl)) {
+		if (past_time(fl->fl_downgrade_time))
+			lease_modify(before, F_RDLCK);
+		if (past_time(fl->fl_break_time))
+			lease_modify(before, F_UNLCK);
 		if (fl == *before)	/* lease_modify may have freed fl */
 			before = &fl->fl_next;
 	}
@@ -1186,7 +1197,7 @@ static void time_out_leases(struct inode *inode)
  */
 int __break_lease(struct inode *inode, unsigned int mode)
 {
-	int error = 0, future;
+	int error = 0;
 	struct file_lock *new_fl, *flock;
 	struct file_lock *fl;
 	unsigned long break_time;
@@ -1203,24 +1214,13 @@ int __break_lease(struct inode *inode, unsigned int mode)
 	if ((flock == NULL) || !IS_LEASE(flock))
 		goto out;
 
+	if (!locks_conflict(flock, new_fl))
+		goto out;
+
 	for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next)
 		if (fl->fl_owner == current->files)
 			i_have_this_lease = 1;
 
-	if (want_write) {
-		/* If we want write access, we have to revoke any lease. */
-		future = F_UNLCK | F_INPROGRESS;
-	} else if (flock->fl_type & F_INPROGRESS) {
-		/* If the lease is already being broken, we just leave it */
-		future = flock->fl_type;
-	} else if (flock->fl_type & F_WRLCK) {
-		/* Downgrade the exclusive lease to a read-only lease. */
-		future = F_RDLCK | F_INPROGRESS;
-	} else {
-		/* the existing lease was read-only, so we can read too. */
-		goto out;
-	}
-
 	if (IS_ERR(new_fl) && !i_have_this_lease
 			&& ((mode & O_NONBLOCK) == 0)) {
 		error = PTR_ERR(new_fl);
@@ -1235,12 +1235,18 @@ int __break_lease(struct inode *inode, unsigned int mode)
 	}
 
 	for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) {
-		if (fl->fl_type != future) {
-			fl->fl_type = future;
+		if (want_write) {
+			if (fl->fl_flags & FL_UNLOCK_PENDING)
+				continue;
+			fl->fl_flags |= FL_UNLOCK_PENDING;
 			fl->fl_break_time = break_time;
-			/* lease must have lmops break callback */
-			fl->fl_lmops->fl_break(fl);
+		} else {
+			if (lease_breaking(flock))
+				continue;
+			fl->fl_flags |= FL_DOWNGRADE_PENDING;
+			fl->fl_downgrade_time = break_time;
 		}
+		fl->fl_lmops->lm_break(fl);
 	}
 
 	if (i_have_this_lease || (mode & O_NONBLOCK)) {
@@ -1264,10 +1270,13 @@ restart:
 	if (error >= 0) {
 		if (error == 0)
 			time_out_leases(inode);
-		/* Wait for the next lease that has not been broken yet */
+		/*
+		 * Wait for the next conflicting lease that has not been
+		 * broken yet
+		 */
 		for (flock = inode->i_flock; flock && IS_LEASE(flock);
 				flock = flock->fl_next) {
-			if (flock->fl_type & F_INPROGRESS)
+			if (locks_conflict(new_fl, flock))
 				goto restart;
 		}
 		error = 0;
@@ -1335,7 +1344,7 @@ int fcntl_getlease(struct file *filp)
 	for (fl = filp->f_path.dentry->d_inode->i_flock; fl && IS_LEASE(fl);
 			fl = fl->fl_next) {
 		if (fl->fl_file == filp) {
-			type = fl->fl_type & ~F_INPROGRESS;
+			type = target_leasetype(fl);
 			break;
 		}
 	}
@@ -1343,50 +1352,23 @@ int fcntl_getlease(struct file *filp)
 	return type;
 }
 
-/**
- *	generic_setlease	-	sets a lease on an open file
- *	@filp: file pointer
- *	@arg: type of lease to obtain
- *	@flp: input - file_lock to use, output - file_lock inserted
- *
- *	The (input) flp->fl_lmops->fl_break function is required
- *	by break_lease().
- *
- *	Called with file_lock_lock held.
- */
-int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
+int generic_add_lease(struct file *filp, long arg, struct file_lock **flp)
 {
 	struct file_lock *fl, **before, **my_before = NULL, *lease;
 	struct dentry *dentry = filp->f_path.dentry;
 	struct inode *inode = dentry->d_inode;
-	int error, rdlease_count = 0, wrlease_count = 0;
+	int error;
 
 	lease = *flp;
 
-	error = -EACCES;
-	if ((current_fsuid() != inode->i_uid) && !capable(CAP_LEASE))
-		goto out;
-	error = -EINVAL;
-	if (!S_ISREG(inode->i_mode))
+	error = -EAGAIN;
+	if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
 		goto out;
-	error = security_file_lock(filp, arg);
-	if (error)
+	if ((arg == F_WRLCK)
+	    && ((dentry->d_count > 1)
+		|| (atomic_read(&inode->i_count) > 1)))
 		goto out;
 
-	time_out_leases(inode);
-
-	BUG_ON(!(*flp)->fl_lmops->fl_break);
-
-	if (arg != F_UNLCK) {
-		error = -EAGAIN;
-		if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
-			goto out;
-		if ((arg == F_WRLCK)
-		    && ((dentry->d_count > 1)
-			|| (atomic_read(&inode->i_count) > 1)))
-			goto out;
-	}
-
 	/*
 	 * At this point, we know that if there is an exclusive
 	 * lease on this file, then we hold it on this filp
@@ -1395,37 +1377,35 @@ int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
 	 * then the file is not open by anyone (including us)
 	 * except for this filp.
 	 */
+	error = -EAGAIN;
 	for (before = &inode->i_flock;
 			((fl = *before) != NULL) && IS_LEASE(fl);
 			before = &fl->fl_next) {
-		if (fl->fl_file == filp)
+		if (fl->fl_file == filp) {
 			my_before = before;
-		else if (fl->fl_type == (F_INPROGRESS | F_UNLCK))
-			/*
-			 * Someone is in the process of opening this
-			 * file for writing so we may not take an
-			 * exclusive lease on it.
-			 */
-			wrlease_count++;
-		else
-			rdlease_count++;
+			continue;
+		}
+		/*
+		 * No exclusive leases if someone else has a lease on
+		 * this file:
+		 */
+		if (arg == F_WRLCK)
+			goto out;
+		/*
+		 * Modifying our existing lease is OK, but no getting a
+		 * new lease if someone else is opening for write:
+		 */
+		if (fl->fl_flags & FL_UNLOCK_PENDING)
+			goto out;
 	}
 
-	error = -EAGAIN;
-	if ((arg == F_RDLCK && (wrlease_count > 0)) ||
-	    (arg == F_WRLCK && ((rdlease_count + wrlease_count) > 0)))
-		goto out;
-
 	if (my_before != NULL) {
-		error = lease->fl_lmops->fl_change(my_before, arg);
+		error = lease->fl_lmops->lm_change(my_before, arg);
 		if (!error)
 			*flp = *my_before;
 		goto out;
 	}
 
-	if (arg == F_UNLCK)
-		goto out;
-
 	error = -EINVAL;
 	if (!leases_enable)
 		goto out;
@@ -1436,6 +1416,62 @@ int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
 out:
 	return error;
 }
+
+int generic_delete_lease(struct file *filp, struct file_lock **flp)
+{
+	struct file_lock *fl, **before;
+	struct dentry *dentry = filp->f_path.dentry;
+	struct inode *inode = dentry->d_inode;
+
+	for (before = &inode->i_flock;
+			((fl = *before) != NULL) && IS_LEASE(fl);
+			before = &fl->fl_next) {
+		if (fl->fl_file != filp)
+			continue;
+		return (*flp)->fl_lmops->lm_change(before, F_UNLCK);
+	}
+	return -EAGAIN;
+}
+
+/**
+ *	generic_setlease	-	sets a lease on an open file
+ *	@filp: file pointer
+ *	@arg: type of lease to obtain
+ *	@flp: input - file_lock to use, output - file_lock inserted
+ *
+ *	The (input) flp->fl_lmops->lm_break function is required
+ *	by break_lease().
+ *
+ *	Called with file_lock_lock held.
+ */
+int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
+{
+	struct dentry *dentry = filp->f_path.dentry;
+	struct inode *inode = dentry->d_inode;
+	int error;
+
+	if ((current_fsuid() != inode->i_uid) && !capable(CAP_LEASE))
+		return -EACCES;
+	if (!S_ISREG(inode->i_mode))
+		return -EINVAL;
+	error = security_file_lock(filp, arg);
+	if (error)
+		return error;
+
+	time_out_leases(inode);
+
+	BUG_ON(!(*flp)->fl_lmops->lm_break);
+
+	switch (arg) {
+	case F_UNLCK:
+		return generic_delete_lease(filp, flp);
+	case F_RDLCK:
+	case F_WRLCK:
+		return generic_add_lease(filp, arg, flp);
+	default:
+		BUG();
+	}
+}
 EXPORT_SYMBOL(generic_setlease);
 
 static int __vfs_setlease(struct file *filp, long arg, struct file_lock **lease)
@@ -1453,7 +1489,7 @@ static int __vfs_setlease(struct file *filp, long arg, struct file_lock **lease)
  *	@lease: file_lock to use
  *
  *	Call this to establish a lease on the file.
- *	The (*lease)->fl_lmops->fl_break operation must be set; if not,
+ *	The (*lease)->fl_lmops->lm_break operation must be set; if not,
  *	break_lease will oops!
  *
  *	This will call the filesystem's setlease file method, if
@@ -1751,10 +1787,10 @@ out:
  * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX
  * locks, the ->lock() interface may return asynchronously, before the lock has
  * been granted or denied by the underlying filesystem, if (and only if)
- * fl_grant is set. Callers expecting ->lock() to return asynchronously
+ * lm_grant is set. Callers expecting ->lock() to return asynchronously
  * will only use F_SETLK, not F_SETLKW; they will set FL_SLEEP if (and only if)
  * the request is for a blocking lock. When ->lock() does return asynchronously,
- * it must return FILE_LOCK_DEFERRED, and call ->fl_grant() when the lock
+ * it must return FILE_LOCK_DEFERRED, and call ->lm_grant() when the lock
  * request completes.
  * If the request is for non-blocking lock the file system should return
  * FILE_LOCK_DEFERRED then try to get the lock and call the callback routine
@@ -1764,7 +1800,7 @@ out:
  * grants a lock so the VFS can find out which locks are locally held and do
  * the correct lock cleanup when required.
  * The underlying filesystem must not drop the kernel lock or call
- * ->fl_grant() before returning to the caller with a FILE_LOCK_DEFERRED
+ * ->lm_grant() before returning to the caller with a FILE_LOCK_DEFERRED
  * return code.
  */
 int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf)
@@ -2147,7 +2183,7 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl,
 		}
 	} else if (IS_LEASE(fl)) {
 		seq_printf(f, "LEASE  ");
-		if (fl->fl_type & F_INPROGRESS)
+		if (lease_breaking(fl))
 			seq_printf(f, "BREAKING  ");
 		else if (fl->fl_file)
 			seq_printf(f, "ACTIVE    ");
@@ -2163,7 +2199,7 @@ static void lock_get_status(struct seq_file *f, struct file_lock *fl,
 			       : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE ");
 	} else {
 		seq_printf(f, "%s ",
-			       (fl->fl_type & F_INPROGRESS)
+			       (lease_breaking(fl))
 			       ? (fl->fl_type & F_UNLCK) ? "UNLCK" : "READ "
 			       : (fl->fl_type & F_WRLCK) ? "WRITE" : "READ ");
 	}
@@ -2333,8 +2369,8 @@ EXPORT_SYMBOL(lock_may_write);
 static int __init filelock_init(void)
 {
 	filelock_cache = kmem_cache_create("file_lock_cache",
-			sizeof(struct file_lock), 0, SLAB_PANIC,
-			init_once);
+			sizeof(struct file_lock), 0, SLAB_PANIC, NULL);
+
 	return 0;
 }