locks: convert lease handling to file_lock_context

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Acked-by: Christoph Hellwig <hch@lst.de>

2 files changed, 102 insertions, 155 deletions

diff --git a/fs/locks.c b/fs/locks.c
index e50bb4d9e757..d46e70567b99 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -216,6 +216,7 @@ locks_get_lock_context(struct inode *inode)
 
         INIT_LIST_HEAD(&new->flc_flock);
         INIT_LIST_HEAD(&new->flc_posix);
+        INIT_LIST_HEAD(&new->flc_lease);
 
         /*
          * Assign the pointer if it's not already assigned. If it is, then
@@ -240,6 +241,7 @@ locks_free_lock_context(struct file_lock_context *ctx)
         if (ctx) {
                 WARN_ON_ONCE(!list_empty(&ctx->flc_flock));
                 WARN_ON_ONCE(!list_empty(&ctx->flc_posix));
+                WARN_ON_ONCE(!list_empty(&ctx->flc_lease));
                 kmem_cache_free(flctx_cache, ctx);
         }
 }
@@ -677,22 +679,6 @@ static void locks_wake_up_blocks(struct file_lock *blocker)
         spin_unlock(&blocked_lock_lock);
 }
 
-/* Insert file lock fl into an inode's lock list at the position indicated
- * by pos. At the same time add the lock to the global file lock list.
- *
- * Must be called with the i_lock held!
- */
-static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl)
-{
-        fl->fl_nspid = get_pid(task_tgid(current));
-
-        /* insert into file's list */
-        fl->fl_next = *pos;
-        *pos = fl;
-
-        locks_insert_global_locks(fl);
-}
-
 static void
 locks_insert_lock_ctx(struct file_lock *fl, struct list_head *before)
 {
@@ -701,63 +687,28 @@ locks_insert_lock_ctx(struct file_lock *fl, struct list_head *before)
         locks_insert_global_locks(fl);
 }
 
-/**
- * locks_delete_lock - Delete a lock and then free it.
- * @thisfl_p: pointer that points to the fl_next field of the previous
- *            inode->i_flock list entry
- *
- * Unlink a lock from all lists and free the namespace reference, but don't
- * free it yet. Wake up processes that are blocked waiting for this lock and
- * notify the FS that the lock has been cleared.
- *
- * Must be called with the i_lock held!
- */
-static void locks_unlink_lock(struct file_lock **thisfl_p)
+static void
+locks_unlink_lock_ctx(struct file_lock *fl)
 {
-        struct file_lock *fl = *thisfl_p;
-
         locks_delete_global_locks(fl);
-
-        *thisfl_p = fl->fl_next;
-        fl->fl_next = NULL;
-
+        list_del_init(&fl->fl_list);
         if (fl->fl_nspid) {
                 put_pid(fl->fl_nspid);
                 fl->fl_nspid = NULL;
         }
-
         locks_wake_up_blocks(fl);
 }
 
-/*
- * Unlink a lock from all lists and free it.
- *
- * Must be called with i_lock held!
- */
-static void locks_delete_lock(struct file_lock **thisfl_p,
-                              struct list_head *dispose)
+static void
+locks_delete_lock_ctx(struct file_lock *fl, struct list_head *dispose)
 {
-        struct file_lock *fl = *thisfl_p;
-
-        locks_unlink_lock(thisfl_p);
+        locks_unlink_lock_ctx(fl);
         if (dispose)
                 list_add(&fl->fl_list, dispose);
         else
                 locks_free_lock(fl);
 }
 
-static void
-locks_delete_lock_ctx(struct file_lock *fl, struct list_head *dispose)
-{
-        locks_delete_global_locks(fl);
-        if (fl->fl_nspid) {
-                put_pid(fl->fl_nspid);
-                fl->fl_nspid = NULL;
-        }
-        locks_wake_up_blocks(fl);
-        list_move(&fl->fl_list, dispose);
-}
-
 /* Determine if lock sys_fl blocks lock caller_fl. Common functionality
  * checks for shared/exclusive status of overlapping locks.
  */
@@ -1376,7 +1327,7 @@ int lease_modify(struct file_lock **before, int arg, struct list_head *dispose)
                         printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
                         fl->fl_fasync = NULL;
                 }
-                locks_delete_lock(before, dispose);
+                locks_delete_lock_ctx(fl, dispose);
         }
         return 0;
 }
@@ -1392,20 +1343,17 @@ static bool past_time(unsigned long then)
 
 static void time_out_leases(struct inode *inode, struct list_head *dispose)
 {
-        struct file_lock **before;
-        struct file_lock *fl;
+        struct file_lock_context *ctx = inode->i_flctx;
+        struct file_lock *fl, *tmp;
 
         lockdep_assert_held(&inode->i_lock);
 
-        before = &inode->i_flock;
-        while ((fl = *before) && IS_LEASE(fl) && lease_breaking(fl)) {
+        list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) {
                 trace_time_out_leases(inode, fl);
                 if (past_time(fl->fl_downgrade_time))
-                        lease_modify(before, F_RDLCK, dispose);
+                        lease_modify(&fl, F_RDLCK, dispose);
                 if (past_time(fl->fl_break_time))
-                        lease_modify(before, F_UNLCK, dispose);
-                if (fl == *before)      /* lease_modify may have freed fl */
-                        before = &fl->fl_next;
+                        lease_modify(&fl, F_UNLCK, dispose);
         }
 }
 
@@ -1419,11 +1367,12 @@ static bool leases_conflict(struct file_lock *lease, struct file_lock *breaker)
 static bool
 any_leases_conflict(struct inode *inode, struct file_lock *breaker)
 {
+        struct file_lock_context *ctx = inode->i_flctx;
         struct file_lock *fl;
 
         lockdep_assert_held(&inode->i_lock);
 
-        for (fl = inode->i_flock ; fl && IS_LEASE(fl); fl = fl->fl_next) {
+        list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
                 if (leases_conflict(fl, breaker))
                         return true;
         }
@@ -1447,7 +1396,8 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
 {
         int error = 0;
         struct file_lock *new_fl;
-        struct file_lock *fl, **before;
+        struct file_lock_context *ctx = inode->i_flctx;
+        struct file_lock *fl;
         unsigned long break_time;
         int want_write = (mode & O_ACCMODE) != O_RDONLY;
         LIST_HEAD(dispose);
@@ -1457,6 +1407,12 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
                 return PTR_ERR(new_fl);
         new_fl->fl_flags = type;
 
+        /* typically we will check that ctx is non-NULL before calling */
+        if (!ctx) {
+                WARN_ON_ONCE(1);
+                return error;
+        }
+
         spin_lock(&inode->i_lock);
 
         time_out_leases(inode, &dispose);
@@ -1471,9 +1427,7 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
                         break_time++;   /* so that 0 means no break time */
         }
 
-        for (before = &inode->i_flock;
-                        ((fl = *before) != NULL) && IS_LEASE(fl);
-                        before = &fl->fl_next) {
+        list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
                 if (!leases_conflict(fl, new_fl))
                         continue;
                 if (want_write) {
@@ -1482,17 +1436,16 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
                         fl->fl_flags |= FL_UNLOCK_PENDING;
                         fl->fl_break_time = break_time;
                 } else {
-                        if (lease_breaking(inode->i_flock))
+                        if (lease_breaking(fl))
                                 continue;
                         fl->fl_flags |= FL_DOWNGRADE_PENDING;
                         fl->fl_downgrade_time = break_time;
                 }
                 if (fl->fl_lmops->lm_break(fl))
-                        locks_delete_lock(before, &dispose);
+                        locks_delete_lock_ctx(fl, &dispose);
         }
 
-        fl = inode->i_flock;
-        if (!fl || !IS_LEASE(fl))
+        if (list_empty(&ctx->flc_lease))
                 goto out;
 
         if (mode & O_NONBLOCK) {
@@ -1502,12 +1455,13 @@ int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
         }
 
 restart:
-        break_time = inode->i_flock->fl_break_time;
+        fl = list_first_entry(&ctx->flc_lease, struct file_lock, fl_list);
+        break_time = fl->fl_break_time;
         if (break_time != 0)
                 break_time -= jiffies;
         if (break_time == 0)
                 break_time++;
-        locks_insert_block(inode->i_flock, new_fl);
+        locks_insert_block(fl, new_fl);
         trace_break_lease_block(inode, new_fl);
         spin_unlock(&inode->i_lock);
         locks_dispose_list(&dispose);
@@ -1525,10 +1479,8 @@ restart:
                         time_out_leases(inode, &dispose);
                 if (any_leases_conflict(inode, new_fl))
                         goto restart;
-
                 error = 0;
         }
-
 out:
         spin_unlock(&inode->i_lock);
         locks_dispose_list(&dispose);
@@ -1550,13 +1502,17 @@ EXPORT_SYMBOL(__break_lease);
 void lease_get_mtime(struct inode *inode, struct timespec *time)
 {
         bool has_lease = false;
-        struct file_lock *flock;
+        struct file_lock_context *ctx = inode->i_flctx;
+        struct file_lock *fl;
 
-        if (inode->i_flock) {
+        if (ctx && !list_empty_careful(&ctx->flc_lease)) {
                 spin_lock(&inode->i_lock);
-                flock = inode->i_flock;
-                if (flock && IS_LEASE(flock) && (flock->fl_type == F_WRLCK))
-                        has_lease = true;
+                if (!list_empty(&ctx->flc_lease)) {
+                        fl = list_first_entry(&ctx->flc_lease,
+                                                struct file_lock, fl_list);
+                        if (fl->fl_type == F_WRLCK)
+                                has_lease = true;
+                }
                 spin_unlock(&inode->i_lock);
         }
 
@@ -1595,20 +1551,22 @@ int fcntl_getlease(struct file *filp)
 {
         struct file_lock *fl;
         struct inode *inode = file_inode(filp);
+        struct file_lock_context *ctx = inode->i_flctx;
         int type = F_UNLCK;
         LIST_HEAD(dispose);
 
-        spin_lock(&inode->i_lock);
-        time_out_leases(file_inode(filp), &dispose);
-        for (fl = file_inode(filp)->i_flock; fl && IS_LEASE(fl);
-                        fl = fl->fl_next) {
-                if (fl->fl_file == filp) {
+        if (ctx && !list_empty_careful(&ctx->flc_lease)) {
+                spin_lock(&inode->i_lock);
+                time_out_leases(file_inode(filp), &dispose);
+                list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
+                        if (fl->fl_file != filp)
+                                continue;
                         type = target_leasetype(fl);
                         break;
                 }
+                spin_unlock(&inode->i_lock);
+                locks_dispose_list(&dispose);
         }
-        spin_unlock(&inode->i_lock);
-        locks_dispose_list(&dispose);
         return type;
 }
 
@@ -1641,9 +1599,10 @@ check_conflicting_open(const struct dentry *dentry, const long arg)
 static int
 generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **priv)
 {
-        struct file_lock *fl, **before, **my_before = NULL, *lease;
+        struct file_lock *fl, *my_fl = NULL, *lease;
         struct dentry *dentry = filp->f_path.dentry;
         struct inode *inode = dentry->d_inode;
+        struct file_lock_context *ctx;
         bool is_deleg = (*flp)->fl_flags & FL_DELEG;
         int error;
         LIST_HEAD(dispose);
@@ -1651,6 +1610,10 @@ generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **pr
         lease = *flp;
         trace_generic_add_lease(inode, lease);
 
+        ctx = locks_get_lock_context(inode);
+        if (!ctx)
+                return -ENOMEM;
+
         /*
          * In the delegation case we need mutual exclusion with
          * a number of operations that take the i_mutex.  We trylock
@@ -1684,13 +1647,12 @@ generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **pr
          * except for this filp.
          */
         error = -EAGAIN;
-        for (before = &inode->i_flock;
-                        ((fl = *before) != NULL) && IS_LEASE(fl);
-                        before = &fl->fl_next) {
+        list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
                 if (fl->fl_file == filp) {
-                        my_before = before;
+                        my_fl = fl;
                         continue;
                 }
+
                 /*
                  * No exclusive leases if someone else has a lease on
                  * this file:
@@ -1705,9 +1667,8 @@ generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **pr
                         goto out;
         }
 
-        if (my_before != NULL) {
-                lease = *my_before;
-                error = lease->fl_lmops->lm_change(my_before, arg, &dispose);
+        if (my_fl != NULL) {
+                error = lease->fl_lmops->lm_change(&my_fl, arg, &dispose);
                 if (error)
                         goto out;
                 goto out_setup;
@@ -1717,7 +1678,7 @@ generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **pr
         if (!leases_enable)
                 goto out;
 
-        locks_insert_lock(before, lease);
+        locks_insert_lock_ctx(lease, &ctx->flc_lease);
         /*
          * The check in break_lease() is lockless. It's possible for another
          * open to race in after we did the earlier check for a conflicting
@@ -1729,8 +1690,10 @@ generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **pr
          */
         smp_mb();
         error = check_conflicting_open(dentry, arg);
-        if (error)
-                goto out_unlink;
+        if (error) {
+                locks_unlink_lock_ctx(lease);
+                goto out;
+        }
 
 out_setup:
         if (lease->fl_lmops->lm_setup)
@@ -1740,33 +1703,35 @@ out:
         locks_dispose_list(&dispose);
         if (is_deleg)
                 mutex_unlock(&inode->i_mutex);
-        if (!error && !my_before)
+        if (!error && !my_fl)
                 *flp = NULL;
         return error;
-out_unlink:
-        locks_unlink_lock(before);
-        goto out;
 }
 
 static int generic_delete_lease(struct file *filp)
 {
         int error = -EAGAIN;
-        struct file_lock *fl, **before;
+        struct file_lock *fl, *victim = NULL;
         struct dentry *dentry = filp->f_path.dentry;
         struct inode *inode = dentry->d_inode;
+        struct file_lock_context *ctx = inode->i_flctx;
         LIST_HEAD(dispose);
 
+        if (!ctx) {
+                trace_generic_delete_lease(inode, NULL);
+                return error;
+        }
+
         spin_lock(&inode->i_lock);
-        time_out_leases(inode, &dispose);
-        for (before = &inode->i_flock;
-                        ((fl = *before) != NULL) && IS_LEASE(fl);
-                        before = &fl->fl_next) {
-                if (fl->fl_file == filp)
+        list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
+                if (fl->fl_file == filp) {
+                        victim = fl;
                         break;
+                }
         }
         trace_generic_delete_lease(inode, fl);
-        if (fl && IS_LEASE(fl))
-                error = fl->fl_lmops->lm_change(before, F_UNLCK, &dispose);
+        if (victim)
+                error = fl->fl_lmops->lm_change(&victim, F_UNLCK, &dispose);
         spin_unlock(&inode->i_lock);
         locks_dispose_list(&dispose);
         return error;
@@ -2447,56 +2412,37 @@ locks_remove_flock(struct file *filp)
                 fl.fl_ops->fl_release_private(&fl);
 }
 
+static void
+locks_remove_lease(struct file *filp)
+{
+        struct inode *inode = file_inode(filp);
+        struct file_lock_context *ctx = inode->i_flctx;
+        struct file_lock *fl, *tmp;
+        LIST_HEAD(dispose);
+
+        if (!ctx || list_empty(&ctx->flc_lease))
+                return;
+
+        spin_lock(&inode->i_lock);
+        list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list)
+                lease_modify(&fl, F_UNLCK, &dispose);
+        spin_unlock(&inode->i_lock);
+        locks_dispose_list(&dispose);
+}
+
 /*
  * This function is called on the last close of an open file.
  */
 void locks_remove_file(struct file *filp)
 {
-        struct inode * inode = file_inode(filp);
-        struct file_lock *fl;
-        struct file_lock **before;
-        LIST_HEAD(dispose);
-
         /* remove any OFD locks */
         locks_remove_posix(filp, filp);
 
         /* remove flock locks */
         locks_remove_flock(filp);
 
-        if (!inode->i_flock)
-                return;
-
-        spin_lock(&inode->i_lock);
-        before = &inode->i_flock;
-
-        while ((fl = *before) != NULL) {
-                if (fl->fl_file == filp) {
-                        if (IS_LEASE(fl)) {
-                                lease_modify(before, F_UNLCK, &dispose);
-                                continue;
-                        }
-
-                        /*
-                         * There's a leftover lock on the list of a type that
-                         * we didn't expect to see. Most likely a classic
-                         * POSIX lock that ended up not getting released
-                         * properly, or that raced onto the list somehow. Log
-                         * some info about it and then just remove it from
-                         * the list.
-                         */
-                        WARN(1, "leftover lock: dev=%u:%u ino=%lu type=%hhd flags=0x%x start=%lld end=%lld\n",
-                                MAJOR(inode->i_sb->s_dev),
-                                MINOR(inode->i_sb->s_dev), inode->i_ino,
-                                fl->fl_type, fl->fl_flags,
-                                fl->fl_start, fl->fl_end);
-
-                        locks_delete_lock(before, &dispose);
-                        continue;
-                }
-                before = &fl->fl_next;
-        }
-        spin_unlock(&inode->i_lock);
-        locks_dispose_list(&dispose);
+        /* remove any leases */
+        locks_remove_lease(filp);
 }
 
 /**
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 571f113588e9..2ddec3cf81b9 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -969,6 +969,7 @@ struct file_lock {
 struct file_lock_context {
         struct list_head        flc_flock;
         struct list_head        flc_posix;
+        struct list_head        flc_lease;
 };
 
 /* The following constant reflects the upper bound of the file/locking space */
@@ -1990,7 +1991,7 @@ static inline int break_lease(struct inode *inode, unsigned int mode)
          * end up racing with tasks trying to set a new lease on this file.
          */
         smp_mb();
-        if (inode->i_flock)
+        if (inode->i_flctx && !list_empty_careful(&inode->i_flctx->flc_lease))
                 return __break_lease(inode, mode, FL_LEASE);
         return 0;
 }
@@ -2003,7 +2004,7 @@ static inline int break_deleg(struct inode *inode, unsigned int mode)
          * end up racing with tasks trying to set a new lease on this file.
          */
         smp_mb();
-        if (inode->i_flock)
+        if (inode->i_flctx && !list_empty_careful(&inode->i_flctx->flc_lease))
                 return __break_lease(inode, mode, FL_DELEG);
         return 0;
 }