filelock: split leases out of struct file_lock

Add a new struct file_lease and move the lease-specific fields from
struct file_lock to it. Convert the appropriate API calls to take
struct file_lease instead, and convert the callers to use them.

There is zero overlap between the lock manager operations for file
locks and the ones for file leases, so split the lease-related
operations off into a new lease_manager_operations struct.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20240131-flsplit-v3-47-c6129007ee8d@kernel.org
Reviewed-by: NeilBrown <neilb@suse.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>

1 files changed, 80 insertions, 43 deletions

diff --git a/fs/locks.c b/fs/locks.c
index 1a4b01203d3da..33c7f4a8c7293 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -74,12 +74,17 @@ static struct file_lock *file_lock(struct file_lock_core *flc)
 	return container_of(flc, struct file_lock, c);
 }
 
-static bool lease_breaking(struct file_lock *fl)
+static struct file_lease *file_lease(struct file_lock_core *flc)
+{
+	return container_of(flc, struct file_lease, c);
+}
+
+static bool lease_breaking(struct file_lease *fl)
 {
 	return fl->c.flc_flags & (FL_UNLOCK_PENDING | FL_DOWNGRADE_PENDING);
 }
 
-static int target_leasetype(struct file_lock *fl)
+static int target_leasetype(struct file_lease *fl)
 {
 	if (fl->c.flc_flags & FL_UNLOCK_PENDING)
 		return F_UNLCK;
@@ -166,6 +171,7 @@ static DEFINE_SPINLOCK(blocked_lock_lock);
 
 static struct kmem_cache *flctx_cache __ro_after_init;
 static struct kmem_cache *filelock_cache __ro_after_init;
+static struct kmem_cache *filelease_cache __ro_after_init;
 
 static struct file_lock_context *
 locks_get_lock_context(struct inode *inode, int type)
@@ -275,6 +281,18 @@ struct file_lock *locks_alloc_lock(void)
 }
 EXPORT_SYMBOL_GPL(locks_alloc_lock);
 
+/* Allocate an empty lock structure. */
+struct file_lease *locks_alloc_lease(void)
+{
+	struct file_lease *fl = kmem_cache_zalloc(filelease_cache, GFP_KERNEL);
+
+	if (fl)
+		locks_init_lock_heads(&fl->c);
+
+	return fl;
+}
+EXPORT_SYMBOL_GPL(locks_alloc_lease);
+
 void locks_release_private(struct file_lock *fl)
 {
 	struct file_lock_core *flc = &fl->c;
@@ -336,15 +354,25 @@ void locks_free_lock(struct file_lock *fl)
 }
 EXPORT_SYMBOL(locks_free_lock);
 
+/* Free a lease which is not in use. */
+void locks_free_lease(struct file_lease *fl)
+{
+	kmem_cache_free(filelease_cache, fl);
+}
+EXPORT_SYMBOL(locks_free_lease);
+
 static void
 locks_dispose_list(struct list_head *dispose)
 {
-	struct file_lock *fl;
+	struct file_lock_core *flc;
 
 	while (!list_empty(dispose)) {
-		fl = list_first_entry(dispose, struct file_lock, c.flc_list);
-		list_del_init(&fl->c.flc_list);
-		locks_free_lock(fl);
+		flc = list_first_entry(dispose, struct file_lock_core, flc_list);
+		list_del_init(&flc->flc_list);
+		if (flc->flc_flags & (FL_LEASE|FL_DELEG|FL_LAYOUT))
+			locks_free_lease(file_lease(flc));
+		else
+			locks_free_lock(file_lock(flc));
 	}
 }
 
@@ -355,6 +383,13 @@ void locks_init_lock(struct file_lock *fl)
 }
 EXPORT_SYMBOL(locks_init_lock);
 
+void locks_init_lease(struct file_lease *fl)
+{
+	memset(fl, 0, sizeof(*fl));
+	locks_init_lock_heads(&fl->c);
+}
+EXPORT_SYMBOL(locks_init_lease);
+
 /*
  * Initialize a new lock from an existing file_lock structure.
  */
@@ -518,14 +553,14 @@ static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
 
 /* default lease lock manager operations */
 static bool
-lease_break_callback(struct file_lock *fl)
+lease_break_callback(struct file_lease *fl)
 {
 	kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);
 	return false;
 }
 
 static void
-lease_setup(struct file_lock *fl, void **priv)
+lease_setup(struct file_lease *fl, void **priv)
 {
 	struct file *filp = fl->c.flc_file;
 	struct fasync_struct *fa = *priv;
@@ -541,7 +576,7 @@ lease_setup(struct file_lock *fl, void **priv)
 	__f_setown(filp, task_pid(current), PIDTYPE_TGID, 0);
 }
 
-static const struct lock_manager_operations lease_manager_ops = {
+static const struct lease_manager_operations lease_manager_ops = {
 	.lm_break = lease_break_callback,
 	.lm_change = lease_modify,
 	.lm_setup = lease_setup,
@@ -550,7 +585,7 @@ static const struct lock_manager_operations lease_manager_ops = {
 /*
  * Initialize a lease, use the default lock manager operations
  */
-static int lease_init(struct file *filp, int type, struct file_lock *fl)
+static int lease_init(struct file *filp, int type, struct file_lease *fl)
 {
 	if (assign_type(&fl->c, type) != 0)
 		return -EINVAL;
@@ -560,17 +595,14 @@ static int lease_init(struct file *filp, int type, struct file_lock *fl)
 
 	fl->c.flc_file = filp;
 	fl->c.flc_flags = FL_LEASE;
-	fl->fl_start = 0;
-	fl->fl_end = OFFSET_MAX;
-	fl->fl_ops = NULL;
 	fl->fl_lmops = &lease_manager_ops;
 	return 0;
 }
 
 /* Allocate a file_lock initialised to this type of lease */
-static struct file_lock *lease_alloc(struct file *filp, int type)
+static struct file_lease *lease_alloc(struct file *filp, int type)
 {
-	struct file_lock *fl = locks_alloc_lock();
+	struct file_lease *fl = locks_alloc_lease();
 	int error = -ENOMEM;
 
 	if (fl == NULL)
@@ -578,7 +610,7 @@ static struct file_lock *lease_alloc(struct file *filp, int type)
 
 	error = lease_init(filp, type, fl);
 	if (error) {
-		locks_free_lock(fl);
+		locks_free_lease(fl);
 		return ERR_PTR(error);
 	}
 	return fl;
@@ -1395,7 +1427,7 @@ static int posix_lock_inode_wait(struct inode *inode, struct file_lock *fl)
 	return error;
 }
 
-static void lease_clear_pending(struct file_lock *fl, int arg)
+static void lease_clear_pending(struct file_lease *fl, int arg)
 {
 	switch (arg) {
 	case F_UNLCK:
@@ -1407,7 +1439,7 @@ static void lease_clear_pending(struct file_lock *fl, int arg)
 }
 
 /* We already had a lease on this file; just change its type */
-int lease_modify(struct file_lock *fl, int arg, struct list_head *dispose)
+int lease_modify(struct file_lease *fl, int arg, struct list_head *dispose)
 {
 	int error = assign_type(&fl->c, arg);
 
@@ -1442,7 +1474,7 @@ static bool past_time(unsigned long then)
 static void time_out_leases(struct inode *inode, struct list_head *dispose)
 {
 	struct file_lock_context *ctx = inode->i_flctx;
-	struct file_lock *fl, *tmp;
+	struct file_lease *fl, *tmp;
 
 	lockdep_assert_held(&ctx->flc_lock);
 
@@ -1458,8 +1490,8 @@ static void time_out_leases(struct inode *inode, struct list_head *dispose)
 static bool leases_conflict(struct file_lock_core *lc, struct file_lock_core *bc)
 {
 	bool rc;
-	struct file_lock *lease = file_lock(lc);
-	struct file_lock *breaker = file_lock(bc);
+	struct file_lease *lease = file_lease(lc);
+	struct file_lease *breaker = file_lease(bc);
 
 	if (lease->fl_lmops->lm_breaker_owns_lease
 			&& lease->fl_lmops->lm_breaker_owns_lease(lease))
@@ -1480,7 +1512,7 @@ trace:
 }
 
 static bool
-any_leases_conflict(struct inode *inode, struct file_lock *breaker)
+any_leases_conflict(struct inode *inode, struct file_lease *breaker)
 {
 	struct file_lock_context *ctx = inode->i_flctx;
 	struct file_lock_core *flc;
@@ -1511,7 +1543,7 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
 {
 	int error = 0;
 	struct file_lock_context *ctx;
-	struct file_lock *new_fl, *fl, *tmp;
+	struct file_lease *new_fl, *fl, *tmp;
 	unsigned long break_time;
 	int want_write = (mode & O_ACCMODE) != O_RDONLY;
 	LIST_HEAD(dispose);
@@ -1571,7 +1603,7 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
 	}
 
 restart:
-	fl = list_first_entry(&ctx->flc_lease, struct file_lock, c.flc_list);
+	fl = list_first_entry(&ctx->flc_lease, struct file_lease, c.flc_list);
 	break_time = fl->fl_break_time;
 	if (break_time != 0)
 		break_time -= jiffies;
@@ -1590,7 +1622,7 @@ restart:
 	percpu_down_read(&file_rwsem);
 	spin_lock(&ctx->flc_lock);
 	trace_break_lease_unblock(inode, new_fl);
-	locks_delete_block(new_fl);
+	__locks_delete_block(&new_fl->c);
 	if (error >= 0) {
 		/*
 		 * Wait for the next conflicting lease that has not been
@@ -1607,7 +1639,7 @@ out:
 	percpu_up_read(&file_rwsem);
 	locks_dispose_list(&dispose);
 free_lock:
-	locks_free_lock(new_fl);
+	locks_free_lease(new_fl);
 	return error;
 }
 EXPORT_SYMBOL(__break_lease);
@@ -1625,14 +1657,14 @@ void lease_get_mtime(struct inode *inode, struct timespec64 *time)
 {
 	bool has_lease = false;
 	struct file_lock_context *ctx;
-	struct file_lock *fl;
+	struct file_lock_core *flc;
 
 	ctx = locks_inode_context(inode);
 	if (ctx && !list_empty_careful(&ctx->flc_lease)) {
 		spin_lock(&ctx->flc_lock);
-		fl = list_first_entry_or_null(&ctx->flc_lease,
-					      struct file_lock, c.flc_list);
-		if (fl && lock_is_write(fl))
+		flc = list_first_entry_or_null(&ctx->flc_lease,
+					       struct file_lock_core, flc_list);
+		if (flc && flc->flc_type == F_WRLCK)
 			has_lease = true;
 		spin_unlock(&ctx->flc_lock);
 	}
@@ -1667,7 +1699,7 @@ EXPORT_SYMBOL(lease_get_mtime);
  */
 int fcntl_getlease(struct file *filp)
 {
-	struct file_lock *fl;
+	struct file_lease *fl;
 	struct inode *inode = file_inode(filp);
 	struct file_lock_context *ctx;
 	int type = F_UNLCK;
@@ -1739,9 +1771,9 @@ check_conflicting_open(struct file *filp, const int arg, int flags)
 }
 
 static int
-generic_add_lease(struct file *filp, int arg, struct file_lock **flp, void **priv)
+generic_add_lease(struct file *filp, int arg, struct file_lease **flp, void **priv)
 {
-	struct file_lock *fl, *my_fl = NULL, *lease;
+	struct file_lease *fl, *my_fl = NULL, *lease;
 	struct inode *inode = file_inode(filp);
 	struct file_lock_context *ctx;
 	bool is_deleg = (*flp)->c.flc_flags & FL_DELEG;
@@ -1850,7 +1882,7 @@ out:
 static int generic_delete_lease(struct file *filp, void *owner)
 {
 	int error = -EAGAIN;
-	struct file_lock *fl, *victim = NULL;
+	struct file_lease *fl, *victim = NULL;
 	struct inode *inode = file_inode(filp);
 	struct file_lock_context *ctx;
 	LIST_HEAD(dispose);
@@ -1890,7 +1922,7 @@ static int generic_delete_lease(struct file *filp, void *owner)
  *	The (input) flp->fl_lmops->lm_break function is required
  *	by break_lease().
  */
-int generic_setlease(struct file *filp, int arg, struct file_lock **flp,
+int generic_setlease(struct file *filp, int arg, struct file_lease **flp,
 			void **priv)
 {
 	struct inode *inode = file_inode(filp);
@@ -1937,7 +1969,7 @@ lease_notifier_chain_init(void)
 }
 
 static inline void
-setlease_notifier(int arg, struct file_lock *lease)
+setlease_notifier(int arg, struct file_lease *lease)
 {
 	if (arg != F_UNLCK)
 		srcu_notifier_call_chain(&lease_notifier_chain, arg, lease);
@@ -1973,7 +2005,7 @@ EXPORT_SYMBOL_GPL(lease_unregister_notifier);
  * may be NULL if the lm_setup operation doesn't require it.
  */
 int
-vfs_setlease(struct file *filp, int arg, struct file_lock **lease, void **priv)
+vfs_setlease(struct file *filp, int arg, struct file_lease **lease, void **priv)
 {
 	if (lease)
 		setlease_notifier(arg, *lease);
@@ -1986,7 +2018,7 @@ EXPORT_SYMBOL_GPL(vfs_setlease);
 
 static int do_fcntl_add_lease(unsigned int fd, struct file *filp, int arg)
 {
-	struct file_lock *fl;
+	struct file_lease *fl;
 	struct fasync_struct *new;
 	int error;
 
@@ -1996,14 +2028,14 @@ static int do_fcntl_add_lease(unsigned int fd, struct file *filp, int arg)
 
 	new = fasync_alloc();
 	if (!new) {
-		locks_free_lock(fl);
+		locks_free_lease(fl);
 		return -ENOMEM;
 	}
 	new->fa_fd = fd;
 
 	error = vfs_setlease(filp, arg, &fl, (void **)&new);
 	if (fl)
-		locks_free_lock(fl);
+		locks_free_lease(fl);
 	if (new)
 		fasync_free(new);
 	return error;
@@ -2626,7 +2658,7 @@ locks_remove_flock(struct file *filp, struct file_lock_context *flctx)
 static void
 locks_remove_lease(struct file *filp, struct file_lock_context *ctx)
 {
-	struct file_lock *fl, *tmp;
+	struct file_lease *fl, *tmp;
 	LIST_HEAD(dispose);
 
 	if (list_empty(&ctx->flc_lease))
@@ -2755,14 +2787,16 @@ static void lock_get_status(struct seq_file *f, struct file_lock_core *flc,
 	} else if (flc->flc_flags & FL_FLOCK) {
 		seq_puts(f, "FLOCK  ADVISORY  ");
 	} else if (flc->flc_flags & (FL_LEASE|FL_DELEG|FL_LAYOUT)) {
-		type = target_leasetype(fl);
+		struct file_lease *lease = file_lease(flc);
+
+		type = target_leasetype(lease);
 
 		if (flc->flc_flags & FL_DELEG)
 			seq_puts(f, "DELEG  ");
 		else
 			seq_puts(f, "LEASE  ");
 
-		if (lease_breaking(fl))
+		if (lease_breaking(lease))
 			seq_puts(f, "BREAKING  ");
 		else if (flc->flc_file)
 			seq_puts(f, "ACTIVE    ");
@@ -2945,6 +2979,9 @@ static int __init filelock_init(void)
 	filelock_cache = kmem_cache_create("file_lock_cache",
 			sizeof(struct file_lock), 0, SLAB_PANIC, NULL);
 
+	filelease_cache = kmem_cache_create("file_lock_cache",
+			sizeof(struct file_lease), 0, SLAB_PANIC, NULL);
+
 	for_each_possible_cpu(i) {
 		struct file_lock_list_struct *fll = per_cpu_ptr(&file_lock_list, i);