lockless get_write_access/deny_write_access

new helpers: atomic_inc_unless_negative()/atomic_dec_unless_positive()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 0 insertions, 46 deletions

diff --git a/fs/namei.c b/fs/namei.c
index e04f15ae4b0..d286cbc3f3e 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -341,52 +341,6 @@ ok:
 	return security_inode_exec_permission(inode, flags);
 }
 
-/*
- * get_write_access() gets write permission for a file.
- * put_write_access() releases this write permission.
- * This is used for regular files.
- * We cannot support write (and maybe mmap read-write shared) accesses and
- * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
- * can have the following values:
- * 0: no writers, no VM_DENYWRITE mappings
- * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
- * > 0: (i_writecount) users are writing to the file.
- *
- * Normally we operate on that counter with atomic_{inc,dec} and it's safe
- * except for the cases where we don't hold i_writecount yet. Then we need to
- * use {get,deny}_write_access() - these functions check the sign and refuse
- * to do the change if sign is wrong. Exclusion between them is provided by
- * the inode->i_lock spinlock.
- */
-
-int get_write_access(struct inode * inode)
-{
-	spin_lock(&inode->i_lock);
-	if (atomic_read(&inode->i_writecount) < 0) {
-		spin_unlock(&inode->i_lock);
-		return -ETXTBSY;
-	}
-	atomic_inc(&inode->i_writecount);
-	spin_unlock(&inode->i_lock);
-
-	return 0;
-}
-
-int deny_write_access(struct file * file)
-{
-	struct inode *inode = file->f_path.dentry->d_inode;
-
-	spin_lock(&inode->i_lock);
-	if (atomic_read(&inode->i_writecount) > 0) {
-		spin_unlock(&inode->i_lock);
-		return -ETXTBSY;
-	}
-	atomic_dec(&inode->i_writecount);
-	spin_unlock(&inode->i_lock);
-
-	return 0;
-}
-
 /**
  * path_get - get a reference to a path
  * @path: path to get the reference to