In the event that we get an F_UNLCK request on an inode that has no lock
context, there is no reason to allocate one. Change
locks_get_lock_context to take a "type" pointer and avoid allocating a
new context if it's F_UNLCK.

Then, fix the callers to return appropriately if that function returns
NULL.

Signed-off-by: Jeff Layton <[email protected]>
---
 fs/locks.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/fs/locks.c b/fs/locks.c
index 0915a3ead897..7be49ad1c902 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -203,11 +203,11 @@ static struct kmem_cache *flctx_cache __read_mostly;
 static struct kmem_cache *filelock_cache __read_mostly;
 
 static struct file_lock_context *
-locks_get_lock_context(struct inode *inode)
+locks_get_lock_context(struct inode *inode, int type)
 {
        struct file_lock_context *new;
 
-       if (likely(inode->i_flctx))
+       if (likely(inode->i_flctx) || type == F_UNLCK)
                goto out;
 
        new = kmem_cache_alloc(flctx_cache, GFP_KERNEL);
@@ -877,9 +877,12 @@ static int flock_lock_file(struct file *filp, struct 
file_lock *request)
        bool found = false;
        LIST_HEAD(dispose);
 
-       ctx = locks_get_lock_context(inode);
-       if (!ctx)
-               return -ENOMEM;
+       ctx = locks_get_lock_context(inode, request->fl_type);
+       if (!ctx) {
+               if (request->fl_type != F_UNLCK)
+                       return -ENOMEM;
+               return (request->fl_flags & FL_EXISTS) ? -ENOENT : 0;
+       }
 
        if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK)) {
                new_fl = locks_alloc_lock();
@@ -945,9 +948,9 @@ static int __posix_lock_file(struct inode *inode, struct 
file_lock *request, str
        bool added = false;
        LIST_HEAD(dispose);
 
-       ctx = locks_get_lock_context(inode);
+       ctx = locks_get_lock_context(inode, request->fl_type);
        if (!ctx)
-               return -ENOMEM;
+               return (request->fl_type == F_UNLCK) ? 0 : -ENOMEM;
 
        /*
         * We may need two file_lock structures for this operation,
@@ -1610,9 +1613,9 @@ 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);
+       ctx = locks_get_lock_context(inode, arg);
        if (!ctx)
-               return -ENOMEM;
+               return (arg == F_UNLCK) ? 0 : -ENOMEM;
 
        /*
         * In the delegation case we need mutual exclusion with
-- 
2.1.0

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